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1.
Front Public Health ; 12: 1332884, 2024.
Article in English | MEDLINE | ID: mdl-38689768

ABSTRACT

Background: In this study, we investigated the association between motivation, cognitive load, difficulty, and performance in a stroke education outreach program implemented for middle school students. Methods: Various interactive instructional activities were developed to engage students throughout the program to assess cognitive and intrinsic load arising from learner implementation of various tasks in a stroke education program for middle school kids. Performance was measured using a post-test to assess knowledge gained by the 6th, 7th, and 8th-grade middle school students. A short questionnaire was also administered to collect data on students' motivation using the ARCS model to asses attention, relevance, confidence, and satisfaction. In addition, we evaluated difficulty level and cognitive load. The relationship between performance and motivation was assessed using Pearson's correlation. Results: In our results, there was no significant difference (p > 0.05) in performance between the 6th, 7th, and 8th-grade students. The difference in performance, cognitive load (mental effort and difficulty), or motivation between the 6th, 7th, and 8 t-grade students was not significant (p > 0.05). The correlation between motivation and performance was significant (r = 0.87, p = 0.001), while the correlation between mental effort and performance was not significant (r = 0.34, p = 0.270). Also, the correlation between difficulty and performance was not significant (r = 0.38, p = 0.361). In the ARCS motivation model, attention, and confidence received the lowest mean scores (3.9), while relevance received the highest score (4.3). Conclusion: Our findings reveal the importance of implementing novel activities to enhance students' motivation to improve performance in the implementation of stroke education outreach programs for middle school students.


Subject(s)
Cognition , Motivation , Stroke , Students , Humans , Female , Male , Adolescent , Students/psychology , Child , Stroke/prevention & control , Health Education/methods , Surveys and Questionnaires , Schools
2.
Anat Sci Educ ; 17(2): 263-273, 2024 Mar.
Article in English | MEDLINE | ID: mdl-37772635

ABSTRACT

Basic science, clinical science, and health system science (HSS) have become three pillars of integration upon which modern, post-Flexner, medical education is now based. Because of this new approach to curricular integration in a clinical presentation curruculum, medical training is now placed in the context of healthcare delivery. This study described the design, implementation, and assessment of an integrated teaching strategy, including the effect on students' performance in a medical neuroscience course's summative and formative examinations of an integrated clinical presentation curriculum. The integrated teaching of basic science content, clinical case discussion, and HSS was performed in the first year of an allopathic integrated pre-clerkship curriculum. The two cohorts were from two different years, spring 2018 and 2019. The acceptance of the integrated teaching strategy by medical students was above 80% in all categories that were assessed, including enhancing the integrated experience in learning basic and clinical science materials in the context of HSS; understanding of the learning lessons; facilitation of self-directed learning; provision of a better learning environment; and a holistic understanding of materials including the relevance of HSS issues in the discussion of neurological cases in the medical career of the students. More than 90% of the students scored ≥70% in summative questions mapped to the four learning objectives of the integrated teaching session. The objectives are the correlation of structure to specific functions (94.0 ± 0.21), clinical anatomical features of the nervous system (95.0 ± 0.27), cross-sectional features of the nervous system (96.0 ± 0.31), and the effect of lesions on the structure and functional pathways of the nervous system (97.0 ± 0.34). This result was significantly higher when compared to students' performance in the non-integrated teaching cohort (p < 0.05). Formative assessments (F(7,159) = 92.52, p < 0.001) were significantly different between the two groups. When medical students were evaluated using the same questions for formative assessment, they performed better in the integrated teaching cohort (*p < 0.05) compared to the non-integrated teaching cohort (**p < 0.05).


Subject(s)
Anatomy , Education, Medical, Undergraduate , Students, Medical , Humans , Cross-Sectional Studies , Anatomy/education , Curriculum , Learning
3.
Int J Mol Sci ; 24(7)2023 Apr 06.
Article in English | MEDLINE | ID: mdl-37047786

ABSTRACT

The two-hit model has been proposed to explain the effects of diabetes on mothers who are already in a putative subclinical damaged state and then undergo neuronal damage during the delivery process. However, the anatomical and pathophysiological mechanisms are not well understood. Our overarching hypothesis in this review paper is that pregnant women who are diabetic have a damaged peripheral nervous system, constituting the "first hit" hypothesis. The delivery process itself-the "second hit"-can produce neurological damage to the mother. Women with diabetes mellitus (DM) are at risk for neurological damage during both hits, but the cumulative effects of both "hits" pose a greater risk of neurological damage and pathophysiological changes during delivery. In our analysis, we introduce the different steps of our concept paper. Subsequently, we describe each of the topics. First, we outline the mechanisms by which diabetes acts as a detrimental variable in neuropathy by focusing on the most common form of diabetic neuropathy, diabetic distal symmetrical polyneuropathy, also known as distal sensorimotor neuropathy. The possible role of macrosomia in causing diabetic neuropathy and obstetric neurological injury is discussed. Second, we describe how vaginal delivery can cause various obstetrical neurological syndromes and pathophysiological changes. Third, we highlight the risk of obstetric neuropathy and discuss anatomical sites at which lesions may occur, including lesions during delivery. Fourth, we characterize the pathophysiological pathways involved in the causation of diabetic neuropathy. Finally, we highlight diabetic damage to sensory vs. motor nerves, including how hyperglycemia causes different types of damage depending on the location of nerve cell bodies.


Subject(s)
Diabetes Mellitus , Diabetic Neuropathies , Hyperglycemia , Pregnancy , Humans , Female , Diabetic Neuropathies/pathology
4.
Anat Sci Educ ; 14(6): 699-710, 2021 Nov.
Article in English | MEDLINE | ID: mdl-33915035

ABSTRACT

The implementation of an integrated medical neuroscience course by technologically pivoting an in-person neuroscience course to online using an adaptive blended method may provide a unique approach for teaching a medical neuroscience course during the Covid-19 pandemic. An adaptive blended learning method was developed in response to the requirements necessitated by the Covid-19 pandemic. This model combined pedagogical needs with digital technology using online learning activities to implement student learning in a medical neuroscience course for year one medical students. This approach provided medical students with an individually customized learning opportunity in medical neuroscience. The students had the complete choice to engage the learning system synchronously or asynchronously and learn neuroscience materials at different locations and times in response to the demands required to deal with the pandemic. Students' performance in summative and formative examinations of the adaptive blended learning activities were compared with the previous performance obtained the previous year when the contents of the medical neuroscience course were implemented using the conventional "face-to-face" learning approach. While the cohort of our students in 2019 and 2020 changed, the contents, sessions, volume of material, and assessment were constant. This enabled us to compare the results of the 2019 and 2020 classes. Overall, students' performance was not significantly different between the adaptive blended learning and the in-person approach. More students scored between 70% and 79% during the adaptive blended learning compared with in-class teaching, while more students scored between 80% and 89% during the in-person learning than during the adaptive blended learning. Finally, the percentage of students that scored >90% was not significantly different for both Years 2019 and 2020. The adaptive blended learning approach was effective in enhancing academic performance for high-performing medical students. It also permitted the early identification of underachieving students, thereby serving as an early warning sign to permit timely intervention.


Subject(s)
Anatomy , COVID-19 , Students, Medical , Anatomy/education , Curriculum , Humans , Pandemics , SARS-CoV-2
5.
Med Sci Educ ; 31(2): 733-743, 2021 Apr.
Article in English | MEDLINE | ID: mdl-33850633

ABSTRACT

Background: The COVID-19 pandemic revealed existing gaps in the medical educational system that is heavily dependent on the presence of medical students and teachers in laboratory and class for instruction. This affects continuity in the implementation of the neuroanatomy component of the medical neuroscience laboratory activities during COVID-19. We hypothesized that pivoting wet laboratory neuroanatomy activities to online using an adaptive flexible blended method might represent an effective approach in the implementation of laboratory neuroanatomy activities during a pandemic. Methods: The current study describes an adaptive flexible blended learning approach that systematically mixes virtual face-to-face interaction activities with the online learning of brain structures, and the discussion of clinical cases. Learning materials are delivered through both synchronous and asynchronous modes, and Year 1 medical students learn neuroanatomy laboratory activities at different locations and different times. Student performances in the adaptive flexible blended learning approach were compared with the learning of similar activities during an in-person implementation of neuroscience laboratory activities. Results: The results of using this adaptive flexible blended learning approach provided an autonomous independent learning, self-study approach that broadened student performance such that we have more students scoring between 80 and 89%, whereas the in-person learning resulted in most of the students scoring > 90% in the medical neuroscience laboratory activities. Conclusion: An adaptive flexible blended learning approach that combined virtual face-to-face instruction using digital technology with online learning of neuroscience laboratory activities provided a unique educational experience for Year 1 medical students to learn neuroscience laboratory activities during the COVID-19 pandemic.

6.
Med Hypotheses ; 144: 109924, 2020 Nov.
Article in English | MEDLINE | ID: mdl-32512492

ABSTRACT

Piriformis syndrome is described as a neuromuscular condition which occurs when the sciatic nerve is compressed and/or irritated by the piriformis muscle. It is characterized by acute tenderness in the buttock with sciatica-like pain radiating into the posterior aspect of the thigh, leg, and foot. The neurogenic leg and foot pain experienced with this condition is consistent with involvement of the sciatic nerve. However, the posterior thigh pain associated with piriformis syndrome is due to involvement of the posterior femoral cutaneous nerve (i.e., posterior cutaneous nerve of the thigh), which is a branch of the sacral plexus independent of the sciatic nerve. This nerve is rarely mentioned relative to piriformis syndrome even though posterior thigh pain is more prevalent in patients than leg and foot pain. In the few instances when the posterior femoral cutaneous nerve is referenced relative to piriformis syndrome the neuralgic signs associated with it are attributed to compression by piriformis. Yet, given the dramatic size difference between the sciatic and posterior femoral cutaneous nerves one would expect direct piriformis compression to impact the sciatic nerve first and produce leg/foot pain at a far greater frequency than posterior thigh pain. However, the opposite is seen in the literature, which raises the question, what underlying mechanism is responsible for this phenomenon? It is hypothesized that the prevalence of posterior femoral cutaneous nerve involvement in piriformis syndrome is due to compression of the inferior gluteal vein by a hypertrophied piriformis muscle.


Subject(s)
Piriformis Muscle Syndrome , Buttocks , Humans , Leg , Lumbosacral Plexus , Piriformis Muscle Syndrome/complications , Sciatic Nerve
7.
Med Sci Educ ; 30(3): 1177-1185, 2020 Sep.
Article in English | MEDLINE | ID: mdl-34457780

ABSTRACT

BACKGROUND: The integration of patient encounters into the first year of the medical school curriculum is known to be of vital importance in the development of critical thinking and communication skills. We investigated whether exposure of first year medical students to patient encounters during a first year medical school neuroscience course result in a high level of motivation associated with the clinical encounter, and whether this high level of motivation translates to higher academic performance as measured by their performance on formative and summative examinations. METHODS: First year medical students interacted with patients presenting with different neurological disorders in a small group informal session. Following the small group interactions with patients, students participated in a large group debriefing session involving discussions with peers, biomedical sciences faculty, and clinicians. Students then completed a survey designed to assess their motivation in correspondence with the Attention, Relevance, Confidence, and Satisfaction (ARCS) model of motivation. These results were then correlated with students' performance in the neuroscience examinations. RESULTS: The total mean score was high for all categories of the ARCS model of motivation (4.26/5) and was highest for Relevance (4.46/5). When these motivation scores were correlated with students' performance on the formative and summative examinations, a significant positive correlation was found between motivation and performance on both the formative (r = 0.85) and summative (r = 0.95) neuroscience examinations. CONCLUSION: Encounters with patients presenting with neurological disorders during a first year medical neuroscience course result in a high level of motivation associated with the clinical encounter, and this was positively correlated with their academic performance.

8.
Med Sci Educ ; 30(4): 1561-1568, 2020 Dec.
Article in English | MEDLINE | ID: mdl-34457824

ABSTRACT

PURPOSE: Empathy tends to decline during medical education, typically beginning in the third year of medical school and often continuing throughout residency and the physician's medical career. The purpose of this study was to determine if first year medical student empathy is affected by small group interactions with patients with neurological disorders, and to investigate if changes in empathy persisted over time. MATERIALS AND METHODS: Eighty first year medical students participating in a Neuroscience Module interacted with a variety of neurological patients in a small group informational session. Prior to the experience, participants completed the Jefferson Scale of Physician Empathy-Student (JSPE-S) version. After the experience, students completed a post-test JSPE-S questionnaire, and a final post-post-test JSPE-S questionnaire was completed 5 weeks later. Empathy scores were compared with a repeated measures MANOVA. The relationship between gender and empathy, and the effect of the age of the neurological patients on empathy scores were also examined. RESULTS: Empathy scores for seventy-one students who completed the JSPE-S questionnaires were analyzed. Students had significantly higher empathy immediately after the patient interaction experience, and the change in empathy was sustained over the course of 5 weeks (p = 0.015). The age of the neurological patients had a significant effect on empathy scores. There was no significant difference between empathy scores and gender. CONCLUSIONS: This study supports the incorporation of a group patient interaction experience into the medical school curriculum as an inexpensive and practical method of enhancing medical student empathy in a non-clinical setting.

9.
Clin Anat ; 33(1): 128-135, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31606904

ABSTRACT

Implementing educational activities, such as a wet lab with cadaveric brain dissection, is known to have a direct impact on medical students' motivation. These activities demonstrate the clinical relevance of concepts taught in the classroom setting. The correlation between motivation and academic performance is not clear. First year medical students participated in wet lab activities. The wet lab included cadaveric dissection of the surface and internal anatomy of the brain, as well as discussions facilitated by the neuroscience faculty and clinicians. Discussions were centered around the clinical relevance of the neuroanatomical features dissected during the wet laboratory activities. Following completion of the laboratory activities, students completed a survey, which was used to assess the students' motivation for learning neuroanatomy based on the Attention, Relevance, Confidence, Satisfaction (ARCS) model of motivation. These results were then correlated with performance on a laboratory examination that tested three-dimensional and cross-sectional knowledge of neuroanatomy and practical skills including the use of imaging techniques. The total mean score of motivation was generally high for all categories of ARCS model of motivation (4.26/5) and was highest for Relevance (4.46/5). When these results were correlated with students' performance on the lab examination, a positive correlation between students' motivation and lab examination scores was found (R2 = 0.877). Implementation of the neuroanatomy cadaveric dissection lab led to increased student motivation, which was positively correlated with students' academic performance. Clin. Anat. 32:128-135, 2019. © 2019 Wiley Periodicals, Inc.


Subject(s)
Academic Performance , Dissection/education , Education, Medical, Undergraduate/methods , Motivation , Neuroanatomy/education , Brain/anatomy & histology , Cadaver , Educational Measurement , Female , Humans , Male , Surveys and Questionnaires
10.
Eur. j. anat ; 23(2): 83-90, mar. 2019. ilus, tab
Article in English | IBECS | ID: ibc-182418

ABSTRACT

The lumbosacral plexus is formed by the ventral rami of L2-S3 and provides sensory and motor branches to the lower extremity. The spatial orientation of the lumbar portion of the plexus above the pelvic brim leaves it particularly susceptible to intrapartum injury by the fetal head. Such lesions are subdivided into two groups: upper lumbar plexus (L1-L4) and lumbosacral trunk (L4-L5). Given the root levels involved, upper lumbar plexus lesions produce symptoms suggestive of iliohypogastric, ilioinguinal, genitofemoral, femoral, and obturator neuropathies or L4 radiculopathies. Alternatively, involvement of the lumbosacral trunk can imitate a common fibular (peroneal) neuropathy or L5 radiculopathy. This symptomatic overlap with various neuropathies and radiculopathies, makes diagnosis of such lesions particularly challenging. To assist in the clinical diagnosis of intrapartum lumbosacral plexopathies, we provide an overview of the motor, sensory, and reflex deficits associated with such lesions and establish the clinical profile of such patients by presenting case studies from the literature of lumbosacral plexopathies. Only cases from the literature involving women who delivered via cesarean section are explored to isolate the presentation of these lesions from injuries related to birth trauma.Based on this overview, we offer differential diagnostic tools which can be utilized to aid in the identification and subsequent treatment of intrapartum lesions to the lumbar portion of the lumbosacral plexus


No disponible


Subject(s)
Humans , Female , Pregnancy , Adult , Lumbosacral Plexus/anatomy & histology , Lumbosacral Plexus/injuries , Peroneal Nerve/anatomy & histology , Tibial Nerve/anatomy & histology , Brachial Plexus Neuropathies , Radiculopathy , Peroneal Nerve/injuries , Tibial Nerve/injuries , Diagnosis, Differential
11.
Anat Sci Educ ; 11(5): 478-487, 2018 Sep.
Article in English | MEDLINE | ID: mdl-29251834

ABSTRACT

The complexity of the material being taught in clinical neuroscience within the medical school curriculum requires creative pedagogies to teach medical students effectively. Many clinical teaching strategies have been developed and are well described to address these challenges. However, only a few have been evaluated to determine their impact on the performance of students studying clinical neuroscience. Interactive, 2-hour, self-directed small-group interactive clinical case-based learning sessions were conducted weekly for 4 weeks to integrate concepts learned in the corresponding didactic lectures. Students in the small groups analyzed cases of patients suffering from neurological disease that were based on eight learning objectives that allowed them to evaluate neuroanatomical data and clinical findings before presenting their case analysis to the larger group. Students' performances on the formative quizzes and summative tests were compared to those of first-year medical students in the previous year for whom the self-directed, small-group interactive clinical sessions were not available. There was a significant improvement in the summative performance of first-year medical students with self-directed clinical case learning in the second year (Y2) of teaching clinical neuroscience (P < 0.05) when compared with first-year students in the first year (Y1) for whom the self-directed learning approach was not available. Student performance in the formative assessments between Y1 and Y2 was not significantly different (P = 0.803). A target of ≥70% student scoring above 80% in the final summative examination was met. The current study revealed evidence for the impact and educational outcomes of a self-directed, clinical teaching strategy in a clinical neuroscience curriculum for first-year medical students. Anat Sci Educ 11: 478-487. © 2017 American Association of Anatomists.


Subject(s)
Academic Performance/statistics & numerical data , Education, Medical, Undergraduate/methods , Neuroanatomy/education , Students, Medical/statistics & numerical data , Teaching , Adult , Brain/anatomy & histology , Brain/diagnostic imaging , Curriculum , Education, Medical, Undergraduate/statistics & numerical data , Female , Humans , Male , Program Evaluation , Schools, Medical/organization & administration , Schools, Medical/statistics & numerical data , Young Adult
12.
Am Surg ; 73(11): 1106-10, 2007 Nov.
Article in English | MEDLINE | ID: mdl-18092642

ABSTRACT

This study was designed to determine if trauma causes the release of adult-derived blastomere-like stem cells (BLSCs) from skeletal muscle into the circulating blood of adult pigs. Experimental procedures followed the guidelines of Fort Valley State University's Institutional Animal Care and Utilization Committee. Pigs were traumatized by splenectomy followed by pancreatectomy. Blood samples and skeletal muscle biopsies were taken before and after trauma. Adult-derived BLSCs were isolated from skeletal muscle and blood samples following established procedures. Nontraumatized skeletal muscle contained approximately 277 million BLSCs per gram of muscle. After trauma, skeletal muscle contained approximately 2 million BLSCs per gram of muscle. Blood taken before trauma contained approximately 22 million BLSCs per milliliter, whereas approximately 512 million BLSCs per milliliter were present within the blood after trauma. Blood values were statistically significant with a P < 0.05. This report is the first demonstration that trauma causes the release of adult-derived BLSCs from skeletal muscle into blood. Further studies are required to elucidate the roles that adult-derived BLSCs play in the response to injury and in the healing process. Surgeons must take a role in this evolving field.


Subject(s)
Muscle, Skeletal/pathology , Pancreatectomy/adverse effects , Splenectomy/adverse effects , Totipotent Stem Cells/pathology , Wounds and Injuries/blood , Animals , Cell Count , Disease Models, Animal , Muscle, Skeletal/metabolism , Swine , Wounds and Injuries/pathology
13.
J Cell Mol Med ; 9(3): 753-69, 2005.
Article in English | MEDLINE | ID: mdl-16202227

ABSTRACT

This report reviews three categories of precursor cells present within adults. The first category of precursor cell, the epiblast-like stem cell, has the potential of forming cells from all three embryonic germ layer lineages, e.g., ectoderm, mesoderm, and endoderm. The second category of precursor cell, the germ layer lineage stem cell, consists of three separate cells. Each of the three cells is committed to form cells limited to a specific embryonic germ layer lineage. Thus the second category consists of germ layer lineage ectodermal stem cells, germ layer lineage mesodermal stem cells, and germ layer lineage endodermal stem cells. The third category of precursor cells, progenitor cells, contains a multitude of cells. These cells are committed to form specific cell and tissue types and are the immediate precursors to the differentiated cells and tissues of the adult. The three categories of precursor cells can be readily isolated from adult tissues. They can be distinguished from each other based on their size, growth in cell culture, expressed genes, cell surface markers, and potential for differentiation. This report also discusses new findings. These findings include the karyotypic analysis of germ layer lineage stem cells; the appearance of dopaminergic neurons after implantation of naive adult pluripotent stem cells into a 6-hydroxydopamine-lesioned Parkinson's model; and the use of adult stem cells as transport mechanisms for exogenous genetic material. We conclude by discussing the potential roles of adult-derived precursor cells as building blocks for tissue repair and as delivery vehicles for molecular medicine.


Subject(s)
Stem Cell Transplantation , Stem Cells/cytology , Stem Cells/physiology , Wounds and Injuries/therapy , Adult , Humans , Karyotyping , Mesoderm/cytology , Mesoderm/physiology
14.
Cell Biochem Biophys ; 40(1): 1-80, 2004.
Article in English | MEDLINE | ID: mdl-14983110

ABSTRACT

Tissue restoration is the process whereby multiple damaged cell types are replaced to restore the histoarchitecture and function to the tissue. Several theories have been proposed to explain the phenomenon of tissue restoration in amphibians and in animals belonging to higher orders. These theories include dedifferentiation of damaged tissues, transdifferentiation of lineage-committed progenitor cells, and activation of reserve precursor cells. Studies by Young et al. and others demonstrated that connective tissue compartments throughout postnatal individuals contain reserve precursor cells. Subsequent repetitive single cell-cloning and cell-sorting studies revealed that these reserve precursor cells consisted of multiple populations of cells, including tissue-specific progenitor cells, germ-layer lineage stem cells, and pluripotent stem cells. Tissue-specific progenitor cells display various capacities for differentiation, ranging from unipotency (forming a single cell type) to multipotency (forming multiple cell types). However, all progenitor cells demonstrate a finite life span of 50 to 70 population doublings before programmed cell senescence and cell death occurs. Germ-layer lineage stem cells can form a wider range of cell types than a progenitor cell. An individual germ-layer lineage stem cell can form all cells types within its respective germ-layer lineage (i.e., ectoderm, mesoderm, or endoderm). Pluripotent stem cells can form a wider range of cell types than a single germ-layer lineage stem cell. A single pluripotent stem cell can form cells belonging to all three germ layer lineages. Both germ-layer lineage stem cells and pluripotent stem cells exhibit extended capabilities for self-renewal, far surpassing the limited life span of progenitor cells (50-70 population doublings). The authors propose that the activation of quiescent tissue-specific progenitor cells, germ-layer lineage stem cells, and/or pluripotent stem cells may be a potential explanation, along with dedifferentiation and transdifferentiation, for the process of tissue restoration. Several model systems are currently being investigated to determine the possibilities of using these adult quiescent reserve precursor cells for tissue engineering.


Subject(s)
Cell Differentiation/physiology , Germ Layers/cytology , Pluripotent Stem Cells/cytology , Regeneration/physiology , Tissue Engineering , Transcription Factors , Animals , Antigens, Surface/metabolism , Bone and Bones/metabolism , Cattle , Cell Lineage/physiology , Cellular Senescence/physiology , Connective Tissue/physiology , DNA-Binding Proteins/metabolism , Diabetes Mellitus/therapy , Embryo, Mammalian , Embryo, Nonmammalian , Extremities/physiology , Genetic Therapy , Hematopoietic Stem Cell Transplantation , Humans , Muscle, Skeletal/metabolism , Muscle, Skeletal/transplantation , Myocardial Infarction/therapy , Myogenin/metabolism , Neurodegenerative Diseases/therapy , Octamer Transcription Factor-3 , Pluripotent Stem Cells/transplantation , Rats , Telomerase/metabolism , Urodela/growth & development , Urodela/physiology
15.
Anat Rec A Discov Mol Cell Evol Biol ; 277(1): 178-203, 2004 Mar.
Article in English | MEDLINE | ID: mdl-14983513

ABSTRACT

Undifferentiated cells have been identified in the prenatal blastocyst, inner cell mass, and gonadal ridges of rodents and primates, including humans. After isolation these cells express molecular and immunological markers for embryonic cells, capabilities for extended self-renewal, and telomerase activity. When allowed to differentiate, embryonic stem cells express phenotypic markers for tissues of ectodermal, mesodermal, and endodermal origin. When implanted in vivo, undifferentiated noninduced embryonic stem cells formed teratomas. In this report we describe a cell clone isolated from postnatal rat skeletal muscle and derived by repetitive single-cell clonogenic analysis. In the undifferentiated state it consists of very small cells having a high ratio of nucleus to cytoplasm. The clone expresses molecular and immunological markers for embryonic stem cells. It exhibits telomerase activity, which is consistent with its extended capability for self-renewal. When induced to differentiate, it expressed phenotypic markers for tissues of ectodermal, mesodermal, and endodermal origin. The clone was designated as a postnatal pluripotent epiblastic-like stem cell (PPELSC). The undifferentiated clone was transfected with a genomic marker and assayed for alterations in stem cell characteristics. No alterations were noted. The labeled clone, when implanted into heart after injury, incorporated into myocardial tissues undergoing repair. The labeled clone was subjected to directed lineage induction in vitro, resulting in the formation of islet-like structures (ILSs) that secreted insulin in response to a glucose challenge. This study suggests that embryonic-like stem cells are retained within postnatal mammals and have the potential for use in gene therapy and tissue engineering.


Subject(s)
Colony-Forming Units Assay/methods , Pluripotent Stem Cells/cytology , Pluripotent Stem Cells/physiology , Animals , Animals, Newborn , Male , Rats , Rats, Inbred WF , Rats, Sprague-Dawley , Stem Cells/cytology , Stem Cells/physiology
16.
Anat Rec A Discov Mol Cell Evol Biol ; 276(1): 75-102, 2004 Jan.
Article in English | MEDLINE | ID: mdl-14699636

ABSTRACT

Development of a multicellular organism is accomplished through a series of events that are preprogrammed in the genome. These events encompass cellular proliferation, lineage commitment, lineage progression, lineage expression, cellular inhibition, and regulated apoptosis. The sequential progression of cells through these events results in the formation of the differentiated cells, tissues, and organs that constitute an individual. Although most cells progress through this sequence during development, a few cells leave the developmental continuum to become reserve precursor cells. The reserve precursor cells are involved in the continual maintenance and repair of the tissues and organs throughout the life span of the individual. Until recently it was generally assumed that the precursor cells in postnatal individuals were limited to lineage-committed progenitor cells specific for various tissues. However, studies by Young, his colleagues, and others have demonstrated the presence of two categories of precursor cells that reside within the organs and tissues of postnatal animals. These two categories of precursor cells are lineage-committed (multipotent, tripotent, bipotent, and unipotent) progenitor cells and lineage-uncommitted pluripotent (epiblastic-like, ectodermal, mesodermal, and endodermal) stem cells. These reserve precursor cells provide for the continual maintenance and repair of the organism after birth.


Subject(s)
Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/physiology , Pluripotent Stem Cells/cytology , Pluripotent Stem Cells/physiology , Adult , Animals , Cell Lineage/physiology , Humans
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