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1.
BMC Digit Health ; 2(1): 56, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39290871

RESUMO

Background: To minimize loss of life, modern mass casualty response requires swift identification, efficient triage categorization, and rapid hemorrhage control. Current training methods remain suboptimal. Our objective was to train first responders to triage a mass casualty incident using Virtual Reality (VR) simulation and obtain their impressions of the training's quality and effectiveness.We trained subjects in a triage protocol called Sort, Assess, Lifesaving interventions, and Treatment and/or Transport (SALT) Triage then had them respond to a terrorist bombing of a subway station using a fully immersive virtual reality simulation. We gathered learner reactions to their virtual reality experience and post-encounter debriefing with a custom electronic survey. The survey was designed to gather information about participants' demographics and prior experience, including roles, triage training, and virtual reality experience. We then asked them to evaluate the training and encounter and the system's potential for training others. Results: We received 375 completed evaluation surveys from subjects who experienced the virtual reality encounter. Subjects were primarily paramedics, but also included medical learners as well as other emergency medical service (EMS) professionals. Most participants (95%) recommended the experience for other first responders and rated the simulation (95%) and virtual patients (91%) as realistic. Ninety-four percent (94%) of participants rated the virtual reality simulator as "excellent" or "good." We observed some differences between emergency medical service and medical professionals regarding their prior experience with disaster response training and their opinions on how much the experience contributed to their learning. We observed no differences between subjects with extensive virtual reality experience and those without. Conclusions: Our virtual reality simulator is an automated, customizable, fully immersive virtual reality system for training and assessing personnel in the proper response to a mass casualty incident. Participants perceived the simulator as an adequate alternative to traditional triage and treatment training and believed that the simulator was realistic and effective for training. Prior experience with virtual reality was not a prerequisite for the use of this system. Supplementary Information: The online version contains supplementary material available at 10.1186/s44247-024-00117-5.

2.
Ann Med ; 56(1): 2382947, 2024 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-39078334

RESUMO

BACKGROUND: Medical students in the U.S. must demonstrate urgent and emergent care competence before graduation. Urgent and emergent care competence involves recognizing, evaluating and initiating management of an unstable patient. High-fidelity (HF) simulation can improve urgent and emergent care skills, but because it is resource intense, alternative methods are needed. STUDY OBJECTIVE: Our primary purpose was to use program evaluations to compare medical student experiences with HF and virtual reality (VR) simulations as assessment platforms for urgent and emergent care skills. METHODS: During their emergency medicine clerkship, students at The Ohio State University College of Medicine must demonstrate on HF manikins, competence in recognizing and initiating care of a patient requiring urgent or emergent care. Students evaluated these simulations on a five-point quality scale and answered open-ended questions about simulation strengths and weaknesses. Faculty provided feedback on student competence in delivering urgent or emergent care. In 2022, we introduced VR as an alternative assessment platform. We used Wilcoxon Signed Ranks and Boxplots to compare ratings of HF to VR and McNemar Test to compare competence ratings. Comments were analyzed with summative content analysis or thematic coding. RESULTS: We received at least one evaluation survey from 160 of 216 (74.1%) emergency medicine clerkship students. We were able to match 125 of 216 (57.9%) evaluation surveys for students who completed both. Average ratings of HF simulations were 4.6 of 5, while ratings of VR simulations were slightly lower at 4.4. Comments suggested that feedback from both simulation platforms was valued. Students described VR as novel, immersive, and good preparation for clinical practice. Constructive criticism identified the need for additional practice in the VR environment. Student performance between platforms was significantly different with 91.7% of students achieving competence in HF, but only 65.5% in VR (p≤.001, odds-ratio = 5.75). CONCLUSION: VR simulation functions similarly to HF for formative assessment of urgent and emergent care competence. However, using VR simulation for summative assessment of urgent and emergent care competence must be considered with caution because students require considerable practice and acclimation to the virtual environment.


Medical students found value in using virtual reality simulation as a platform for practice and feedback in a formative assessment arrangement.Students described the virtual reality simulation as immersive and good preparation for clinical practice.Technical difficulties were common and the student learning curve for acclimating and learning how to function in the virtual environment was noteworthy.


Assuntos
Competência Clínica , Medicina de Emergência , Estudantes de Medicina , Realidade Virtual , Humanos , Estudantes de Medicina/estatística & dados numéricos , Medicina de Emergência/educação , Estágio Clínico/métodos , Educação de Graduação em Medicina/métodos , Avaliação Educacional/métodos , Manequins , Ohio , Treinamento com Simulação de Alta Fidelidade/métodos , Avaliação de Programas e Projetos de Saúde
4.
J Am Coll Emerg Physicians Open ; 4(1): e12903, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36817080

RESUMO

As mass casualty incidents continue to escalate in the United States, we must improve frontline responder performance to increase the odds of victim survival. In this article, we describe the First Responder Virtual Reality Simulator, a high-fidelity, fully immersive, automated, programmable virtual reality (VR) simulation designed to train frontline responders to treat and triage victims of mass casualty incidents. First responder trainees don a wireless VR head-mounted display linked to a compatible desktop computer. Trainees see and hear autonomous, interactive victims who are programmed to simulate individuals with injuries consistent with an explosion in an underground space. Armed with a virtual medical kit, responders are tasked with triaging and treating the victims on the scene. The VR environment can be made more challenging by increasing the environmental chaos, adding patients, or increasing the acuity of patient injuries. The VR platform tracks and records their performance as they navigate the disaster scene. Output from the system provides feedback to participants on their performance. Eventually, we hope that the First Responder system will serve both as an effective replacement for expensive conventional training methods as well as a safe and efficient platform for research on current triage protocols.

5.
Med Teach ; : 1-7, 2022 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-36346810

RESUMO

INTRODUCTION: Advances in natural language understanding have facilitated the development of Virtual Standardized Patients (VSPs) that may soon rival human patients in conversational ability. We describe herein the development of an artificial intelligence (AI) system for VSPs enabling students to practice their history taking skills. METHODS: Our system consists of (1) Automated Speech Recognition (ASR), (2) hybrid AI for question identification, (3) classifier to choose between the two systems, and (4) automated speech generation. We analyzed the accuracy of the ASR, the two AI systems, the classifier, and student feedback with 620 first year medical students from 2018 to 2021. RESULTS: System accuracy improved from ∼75% in 2018 to ∼90% in 2021 as refinements in algorithms and additional training data were utilized. Student feedback was positive, and most students felt that practicing with the VSPs was a worthwhile experience. CONCLUSION: We have developed a novel hybrid dialogue system that enables artificially intelligent VSPs to correctly answer student questions at levels comparable with human SPs. This system allows trainees to practice and refine their history-taking skills before interacting with human patients.

6.
Otolaryngol Head Neck Surg ; 163(2): 198-203, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31959055

RESUMO

OBJECTIVE: To provide preclinical medical students early access to otolaryngologists to learn about the specialty, facilitate acquisition of clinical skills, and provide one-on-one mentorship. METHODS: Students are matched with a single otolaryngology faculty mentor from The Ohio State University/Nationwide Children's Hospital and attend 8 hours per month in the clinic or operating room, monthly lectures, and rounds, and they give a final presentation. Mentors complete performance evaluations, and surveys are administered longitudinally until Match Day. RESULTS: Thirty-five students and 17 faculty members have participated in the program since 2015. All mentors and students found the program to be a valuable experience. When compared to nonparticipating students, participants had significantly higher confidence scores for clinical performance, knowledge of anatomy, and familiarity with the department of interest. All students felt the program prepared them well for third and fourth years, and all 8 of the initial program participants successfully matched into residency with 4 entering otolaryngology. DISCUSSION: Medical students face a competitive residency application process in otolaryngology with limited exposure, which creates an opportunity for guidance in the pursuit of matching into this field. This novel preclinical mentorship program prepares students for their clinical years and residency by facilitating acquisition of various competencies. Students gain hands-on clinical exposure in a field of interest and support for navigating the application process. IMPLICATIONS FOR PRACTICE: The structure of this program can be applied to other medical schools or specialties if the individual departments contain adequate resources of teaching faculty willing to participate.


Assuntos
Educação de Graduação em Medicina , Mentores , Otolaringologia/educação , Estágio Clínico
7.
Med Teach ; 41(9): 1053-1059, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31230496

RESUMO

Introduction: Practicing a medical history using standardized patients is an essential component of medical school curricula. Recent advances in technology now allow for newer approaches for practicing and assessing communication skills. We describe herein a virtual standardized patient (VSP) system that allows students to practice their history taking skills and receive immediate feedback. Methods: Our VSPs consist of artificially intelligent, emotionally responsive 3D characters which communicate with students using natural language. The system categorizes the input questions according to specific domains and summarizes the encounter. Automated assessment by the computer was compared to manual assessment by trained raters to assess accuracy of the grading system. Results: Twenty dialogs chosen randomly from 102 total encounters were analyzed by three human and one computer rater. Overall scores calculated by the computer were not different than those provided by the human raters, and overall accuracy of the computer system was 87%, compared with 90% for human raters. Inter-rater reliability was high across 19 of 21 categories. Conclusions: We have developed a virtual standardized patient system that can understand, respond, categorize, and assess student performance in gathering information during a typical medical history, thus enabling students to practice their history-taking skills and receive immediate feedback.


Assuntos
Educação de Graduação em Medicina/métodos , Anamnese/métodos , Relações Médico-Paciente , Realidade Virtual , Análise de Variância , Inteligência Artificial , Humanos , Estudantes de Medicina , Inquéritos e Questionários , Interface Usuário-Computador
8.
JMIR Serious Games ; 6(2): e8, 2018 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-29752249

RESUMO

BACKGROUND: Prenatal counseling at the limits of newborn viability involves sensitive interactions between neonatal providers and families. Empathetic discussions are currently learned through practice in times of high stress. Decision aids may help improve provider communication but have not been universally adopted. Virtual standardized patients are increasingly recognized as a modality for education, but prenatal counseling simulations have not been described. To be valuable as a tool, a virtual patient would need to accurately portray emotions and elicit a realistic response from the provider. OBJECTIVE: To determine if neonatal providers can accurately identify a standardized virtual prenatal patient's emotional states and examine the frequency of empathic responses to statements made by the patient. METHODS: A panel of Neonatologists, Simulation Specialists, and Ethicists developed a dialogue and identified empathic responses. Virtual Antenatal Encounter and Standardized Simulation Assessment (VANESSA), a screen-based simulation of a woman at 23 weeks gestation, was capable of displaying anger, fear, sadness, and happiness through animations. Twenty-four neonatal providers, including a subgroup with an ethics interest, were asked to identify VANESSA's emotions 28 times, respond to statements, and answer open-ended questions. The emotions were displayed in different formats: without dialogue, with text dialogue, and with audio dialogue. Participants completed a post-encounter survey describing demographics and experience. Data were reported using descriptive statistics. Qualitative data from open ended questions (eg, "What would you do?") were examined using thematic analysis. RESULTS: Half of our participants had over 10 years of clinical experience. Most participants reported using medical research (18/23, 78%) and mortality calculators (17/23, 74%). Only the ethics-interested subgroup (10/23, 43%) listed counseling literature (7/10, 70%). Of 672 attempts, participants accurately identified VANESSA's emotions 77.8% (523/672) of the time, and most (14/23, 61%) reported that they were confident in identifying these emotions. The ethics interest group was more likely to choose empathic responses (P=.002). Participants rated VANESSA as easy to use (22/23, 96%) and reported that she had realistic dialogue (15/23, 65%). CONCLUSIONS: This pilot study shows that a prenatal counseling simulation is feasible and can yield useful data on prenatal counseling communication. Our participants showed a high rate of emotion recognition and empathy in their responses.

9.
Acad Emerg Med ; 25(2): 186-195, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28888070

RESUMO

Immersive learning environments that use virtual simulation (VS) technology are increasingly relevant as medical learners train in an environment of restricted clinical training hours and a heightened focus on patient safety. We conducted a consensus process with a breakout group of the 2017 Academic Emergency Medicine Consensus Conference "Catalyzing System Change Through Health Care Simulation: Systems, Competency, and Outcomes." This group examined the current uses of VS in training and assessment, including limitations and challenges in implementing VS into medical education curricula. We discuss the role of virtual environments in formative and summative assessment. Finally, we offer recommended areas of focus for future research examining VS technology for assessment, including high-stakes assessment in medical education. Specifically, we discuss needs for determination of areas of focus for VS training and assessment, development and exploration of virtual platforms, automated feedback within such platforms, and evaluation of effectiveness and validity of VS education.


Assuntos
Medicina de Emergência/educação , Treinamento por Simulação/métodos , Realidade Virtual , Competência Clínica , Currículo , Humanos
10.
Simul Healthc ; 12(2): 124-131, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28704290

RESUMO

INTRODUCTION: Although traditional virtual patient simulations are designed to teach and assess clinical reasoning skills, few employ conversational dialogue with the patients. The virtual standardized patients (VSPs) described herein represent standardized patients that students interview using natural language. Students take histories and develop differential diagnoses of the VSPs as much as they would with standardized or actual patients. The student-VSP interactions are recorded, creating a comprehensive record of questions and the order in which they were asked, which can be analyzed to assess information-gathering skills. Students document the encounter in an electronic medical record created for the VSPs. METHODS: The VSP was developed by integrating a dialogue management system (ChatScript) with emotionally responsive 3D characters created in a high-fidelity game engine (Unity). The system was tested with medical students at the Ohio State University College of Medicine. Students are able to take a history of a VSP, develop a differential diagnosis, and document the encounter in the electronic medical record. RESULTS: Accuracy of the VSP responses ranged from 79% to 86%, depending on the complexity of the case, type of history obtained, and skill of the student. Students were able to accurately develop an appropriate differential diagnosis on the basis of the information provided by the patient during the encounter. CONCLUSIONS: The VSP enables students to practice their history-taking skills before encounters with standardized or actual patients. Future developments will focus on creating an assessment module that will automatically analyze VSP sessions and provide immediate student feedback.


Assuntos
Educação de Graduação em Medicina/métodos , Anamnese/métodos , Simulação de Paciente , Relações Médico-Paciente , Realidade Virtual , Competência Clínica , Tomada de Decisão Clínica , Comunicação , Humanos , Estudantes de Medicina/psicologia , Interface Usuário-Computador
11.
West J Emerg Med ; 16(2): 336-43, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25834684

RESUMO

INTRODUCTION: The oral examination is a traditional method for assessing the developing physician's medical knowledge, clinical reasoning and interpersonal skills. The typical oral examination is a face-to-face encounter in which examiners quiz examinees on how they would confront a patient case. The advantage of the oral exam is that the examiner can adapt questions to the examinee's response. The disadvantage is the potential for examiner bias and intimidation. Computer-based virtual simulation technology has been widely used in the gaming industry. We wondered whether virtual simulation could serve as a practical format for delivery of an oral examination. For this project, we compared the attitudes and performance of emergency medicine (EM) residents who took our traditional oral exam to those who took the exam using virtual simulation. METHODS: EM residents (n=35) were randomized to a traditional oral examination format (n=17) or a simulated virtual examination format (n=18) conducted within an immersive learning environment, Second Life (SL). Proctors scored residents using the American Board of Emergency Medicine oral examination assessment instruments, which included execution of critical actions and ratings on eight competency categories (1-8 scale). Study participants were also surveyed about their oral examination experience. RESULTS: We observed no differences between virtual and traditional groups on critical action scores or scores on eight competency categories. However, we noted moderate effect sizes favoring the Second Life group on the clinical competence score. Examinees from both groups thought that their assessment was realistic, fair, objective, and efficient. Examinees from the virtual group reported a preference for the virtual format and felt that the format was less intimidating. CONCLUSION: The virtual simulated oral examination was shown to be a feasible alternative to the traditional oral examination format for assessing EM residents. Virtual environments for oral examinations should continue to be explored, particularly since they offer an inexpensive, more comfortable, yet equally rigorous alternative.


Assuntos
Medicina de Emergência/educação , Internato e Residência , Critérios de Admissão Escolar , Interface Usuário-Computador , Humanos , Estudos Prospectivos
12.
J Reprod Med ; 59(3-4): 103-9, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24724216

RESUMO

OBJECTIVE: To examine the effects of gonadotropin-releasing hormone (GnRH) antagonist on primordial follicle reserve in the primate ovary. STUDY DESIGN: A prospective basic research study in which 10 juvenile cynomolgus monkeys (Macaca fascicularis) had 1 ovary surgically removed. Six animals were then treated with the GnRH antagonist antide (1.0 mg/kg/day) for 14 days, and 4 animals were treated with vehicle. After treatment the contralateral ovary was removed and both ovaries were prepared for assessment of primordial, primary, and secondary follicle numbers. RESULTS: Antide treatment resulted in a modest (13%) but significant decrease in primordial follicle number in juvenile macaques (p = 0.048, n = 6). Three animals demonstrated a marked reduction in primordial follicles (19%, 25%, 36%) and 3 animals had no (< 5%) change in primordial follicles after antide treatment. Control animals demonstrated no change in primordial follicle number following vehicle treatment. Antide had no effect on primary, secondary, or early antral follicle numbers and did not affect circulating estradiol concentrations. CONCLUSION: In contrast to mice, in which GnRH antagonist treatment markedly reduces primordial follicle reserve, the effect of antide in nonhuman primates was less dramatic and somewhat variable. These data suggest there may be a subset of animals susceptible to the adverse effects of GnRH antagonist on primordial follicle survival.


Assuntos
Hormônio Liberador de Gonadotropina/antagonistas & inibidores , Antagonistas de Hormônios/farmacologia , Macaca fascicularis/fisiologia , Folículo Ovariano/efeitos dos fármacos , Folículo Ovariano/fisiologia , Ovário/efeitos dos fármacos , Animais , Estradiol/sangue , Feminino , Oligopeptídeos/farmacologia , Ovariectomia , Ovário/fisiologia , Ovário/cirurgia , Estudos Prospectivos
13.
Acad Emerg Med ; 18(5): 559-62, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21521404

RESUMO

OBJECTIVES: Oral examination is a method used to evaluate emergency medicine (EM) residents and is a requirement for board certification of emergency physicians. Second Life (SL) is a virtual three-dimensional (3-D) immersive learning environment that has been used for medical education. In this study we explore the use of SL virtual simulation technology to administer mock oral examinations to EM residents. METHODS: This was a prospective observational study of EM residents who had previously completed mock oral examinations, participating in a similar mock oral examination case scenario conducted via SL. EM residents in this training program completed mock oral examinations in a traditional format, conducted face to face with a faculty examiner. All current residents were invited to participate in a similar case scenario conducted via SL for this study. The examinee managed the case while acting as the physician avatar and communicated via headset and microphone from a remote computer with a faculty examiner who acted as the patient avatar. Participants were surveyed regarding their experience with the traditional and virtual formats using a Likert scale. RESULTS: Twenty-seven EM residents participated in the virtual oral examination. None of the examinees had used SL previously. SL proved easy for examinees to log into (92.6%) and navigate (96.3%). All felt comfortable communicating with the examiner via remote computer. Most examinees thought the SL encounter was realistic (92.6%), and many found it more realistic than the traditional format (70.3%). All examinees felt that the virtual examination was fair, objective, and conducted efficiently. A majority preferred to take oral examinations via SL over the traditional format and expressed interest in using SL for other educational experiences (66.6 and 92.6%, respectively). CONCLUSIONS: Application of SL virtual simulation technology is a potential alternative to traditional mock oral examinations for EM residents.


Assuntos
Atitude do Pessoal de Saúde , Avaliação Educacional/métodos , Medicina de Emergência/educação , Internato e Residência , Médicos/psicologia , Certificação , Humanos , Estudos Prospectivos , Sociedades Médicas , Conselhos de Especialidade Profissional , Estados Unidos , Interface Usuário-Computador
14.
Biol Reprod ; 76(2): 218-23, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17050862

RESUMO

The regulation of early follicular growth and development involves a complex interaction of autocrine, paracrine, and endocrine signals. The ability of these factors to regulate follicle growth may depend in part on the extent of vascular delivery to and perfusion of the ovary. Vascular endothelial growth factor A (VEGFA) is a major regulator of vascular physiology in the ovary. VEGFA is produced in numerous ovarian compartments and likely plays a role in the regulation of all phases of follicular growth, from preantral through preovulatory. The aim of the present study was to further evaluate the role of VEGF in early follicle growth by neutralization of endogenous VEGF or VEGF receptors. Adult mice were injected systemically and prepubertal mice were injected directly under the ovarian bursa with antibodies designed to neutralize VEGF or block interaction with its receptors in the ovary. Both systemic and intrabursal injections of VEGF antibody significantly reduced the number of primordial follicles within 1-3 days after administration without affecting primary or secondary follicle numbers. Primordial follicle numbers were not different from control levels by 30 days after VEGFA antibody administration. Administration of antibodies to the kinase domain receptor (KDR), but not the FMS-like tyrosine receptor (FLT1), for VEGF also resulted in a significant decrease in primordial follicles. These data suggest that VEGF plays a vital role in the maintenance and growth of the primordial follicle pool.


Assuntos
Camundongos/crescimento & desenvolvimento , Camundongos/metabolismo , Folículo Ovariano/crescimento & desenvolvimento , Fator A de Crescimento do Endotélio Vascular/metabolismo , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Animais , Anticorpos/administração & dosagem , Anticorpos/imunologia , Anticorpos/farmacologia , Ciclo Estral/efeitos dos fármacos , Feminino , Injeções Intraperitoneais , Folículo Ovariano/efeitos dos fármacos , Fatores de Tempo , Fator A de Crescimento do Endotélio Vascular/imunologia , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/imunologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/imunologia
15.
Fertil Steril ; 83(5): 1333-8, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15866565

RESUMO

OBJECTIVE: To examine the effects of GnRH antagonists on preantral follicle survival in vivo and to investigate whether GnRH antagonist use during cyclophosphamide treatment would protect the ovary and preserve primordial follicle survival in a murine model. DESIGN: Prospective basic research study. SETTING: Research laboratory in an academic medical center. ANIMAL(S): Adult C57Bl/6 mice (5 to 6 weeks old). INTERVENTION(S): Mice received either a single injection of GnRH agonist (leuprolide acetate) on study day -10 or injections of the GnRH antagonist (antide or cetrorelix) on study days -3 and 0. Some animals also received the chemotherapeutic agent cyclophosphamide on day 0. All animals were killed by CO2 asphyxiation on day 7. To examine direct vs. indirect effects, some mice received GnRH antagonist under the bursa of one ovary, with the contralateral ovary receiving vehicle. Ovaries were fixed in Kahle's solution; 7-mum tissue sections were stained with Lillie's allochrome, and preantral follicles were counted on every fifth section. MAIN OUTCOME MEASURE(S): Numbers of primordial, primary, and secondary follicles. RESULT(S): Systemic administration of both GnRH antagonists caused a significant destruction of primordial follicles compared with control mice. Similar results were obtained whether the antagonists were administered systemically or directly to the ovary. Gonadotropin-releasing hormone agonist had no effect on primordial follicle numbers by itself but reduced the follicular depletion caused by cyclophosphamide. CONCLUSION(S): In contrast to the effects of GnRH agonists to reduce chemotherapeutic destruction of primordial follicles, GnRH antagonists do not protect the ovary from the damaging effects of cyclophosphamide. More importantly, GnRH antagonists alone deplete primordial follicles in this murine model, likely through a direct effect on the ovary. Whether these observations apply to other species requires further study.


Assuntos
Hormônio Liberador de Gonadotropina/antagonistas & inibidores , Antagonistas de Hormônios/farmacologia , Folículo Ovariano/citologia , Folículo Ovariano/efeitos dos fármacos , Animais , Feminino , Hormônio Liberador de Gonadotropina/fisiologia , Leuprolida/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Oligopeptídeos/farmacologia , Folículo Ovariano/fisiologia
16.
Biol Reprod ; 68(5): 1736-41, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12606430

RESUMO

The regulation of preantral follicle growth in mammals is poorly understood. The availability of an adequate vascular supply to provide endocrine and paracrine signals may be important during the early states of follicle growth as well as the later states of follicle selection and dominance. The objective of the present study was to investigate whether vascular endothelial growth factor (VEGF) plays a role in preantral follicular development in the rat ovary. Immature (age, 21 days) Sprague-Dawley rats were injected with 500 ng of VEGF in saline or 50 microg of diethylstilbestrol (DES) in oil under the bursa of one ovary. The contralateral ovary was injected with a corresponding volume of vehicle. Rats were killed 48 h later, and the ovaries were removed and analyzed histologically. Intrabursal administration of VEGF significantly increased the number of primary and small secondary, but not of large secondary, preantral follicles in the ovary, similar to the effect of DES (P < 0.05). The VEGF stimulated preantral follicle growth in a time- and dose-dependent manner. Subcutaneous DES administration increased the number of primary and secondary follicles, and both s.c. and intrabursal estrogen administration stimulated VEGF protein expression in the rat ovary. These data indicate that VEGF stimulates preantral follicular development in the rat ovary, is regulated by estrogen, and may be one of the factors that participate in the regulation of early follicle growth in the rat.


Assuntos
Estradiol/análogos & derivados , Folículo Ovariano/efeitos dos fármacos , Ovário/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/farmacologia , Animais , Western Blotting , Dietilestilbestrol/farmacologia , Relação Dose-Resposta a Droga , Estradiol/farmacologia , Estrogênios/farmacologia , Estrogênios não Esteroides/farmacologia , Feminino , Ratos , Ratos Sprague-Dawley , Estimulação Química , Fixação de Tecidos
17.
J Androl ; 23(6): 783-92, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12399523

RESUMO

Methyl xanthines have been used frequently as additives to sperm suspensions in order to improve sperm characteristics. The mechanism of action on spermatozoa is generally assumed to be inhibition of sperm phosphodiesterase activity, resulting in elevation of complementary adenosine monophosphate levels in spermatozoa. The present study was designed to examine the effect of methyl xanthines (pentoxifylline, caffeine, and theophylline) on another important enzyme system, alkaline phosphatase, in boar seminal plasma and spermatozoa. Inhibition of sperm alkaline phosphatase could be distinguished from that of seminal plasma by a paradoxical stimulation by pentoxifylline at lower pH values in spermatozoa. Among the three methyl xanthines, theophylline exhibited the most dramatic inhibition of alkaline phosphatase activity and substrate inhibition was observed with increasing concentrations. Each methyl xanthine had a different action on alkaline phosphatase activity at lower pH; theophylline showed the highest inhibition, caffeine inhibition was not related to pH, and pentoxifylline did not inhibit alkaline phosphatase of seminal plasma and, in fact, it stimulated its activity (or that of a phosphatase with lower pH optimum) in spermatozoa. These results indicate another possible mechanism of action of methyl xanthines on sperm and are in agreement with data indicating that methyl xanthines are not specific inhibitors of sperm phosphodiesterase, because clearly, they inhibit alkaline phosphatase activity as well.


Assuntos
Fosfatase Alcalina/antagonistas & inibidores , Cafeína/farmacologia , Inibidores Enzimáticos/farmacologia , Pentoxifilina/farmacologia , Sêmen/enzimologia , Teofilina/farmacologia , Animais , Concentração de Íons de Hidrogênio , Masculino , Espermatozoides/enzimologia , Suínos
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