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Mochona B, Redda KK, Offringa IA, Allen J, Carpten JD, Stern MC, Reams RR, Wilkie DJ. Mentoring Minority Cancer Researchers of Tomorrow: Comparison of the Face-to-Face, Virtual, and Hybrid Training Methods of the CaRE 2 Summer Cancer Research Education and Training Program. J Cancer Educ 2024:10.1007/s13187-024-02426-9. [PMID: 38520478 DOI: 10.1007/s13187-024-02426-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/10/2024] [Indexed: 03/25/2024]
Abstract
In our previous publication, we reported a framework to develop an undergraduate cancer research training program at Florida A&M University (FAMU) under the umbrella of the Florida-California Cancer Research, Education, and Engagement (CaRE2) Health Equity Center activity by harnessing the resources available at FAMU, the University of Florida (UF), and the University of Southern California (USC) Cancer Centers. The implementation of the CaRE2 face-to-face training platform was dramatically affected by the COVID-19 pandemic during the summer of 2020 and 2021 training periods. However, a concerted effort was made to restructure the face-to-face training model into virtual and hybrid training methods to maintain the continuity of the program during the pandemic. This article compared the three methods to identify the best platform for training URM students in cancer disparity research. The program's effectiveness was measured through motivation, experiences, and knowledge gained by trainees during and one year after the completion of the program. The results showed that the participants were highly positive in their feedback about the professional and academic values of the program. Although the virtual and hybrid methods experienced significant challenges during the pandemic, the hybrid training module offered an "above average" effectiveness in performance, like the face-to-face mentoring platform in mentoring URM students in cancer disparity research.
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Affiliation(s)
- Bereket Mochona
- Department of Chemistry, College of Science & Technology, Florida A&M University, Tallahassee, FL, 32307, USA.
| | - Kinfe K Redda
- College of Pharmacy and Pharmaceutical Sciences, Institute of Public Health, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Ite A Offringa
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - John Allen
- College of Pharmacy and College of Medicine, University of Florida Research and Academic Center, Lake Nona, FL, 32827, USA
| | - John D Carpten
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Mariana C Stern
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Renee R Reams
- College of Pharmacy and Pharmaceutical Sciences, Institute of Public Health, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Diana J Wilkie
- College of Nursing, University of Florida, Gainesville, FL, 32611, USA
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Mochona B, Lyon D, Offringa IA, Redda KK, Reams RR, Odedina F, Wilkie DJ, Stern MC, Carpten JD. Developing a Novel Framework for an Undergraduate Cancer Research Education and Engagement Program for Underrepresented Minority Students: the Florida-California CaRE 2 Research Education Core (REC) Training Program. J Cancer Educ 2021; 36:914-919. [PMID: 32430639 PMCID: PMC7674268 DOI: 10.1007/s13187-020-01762-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lack of substantive research experiences and technical skills mentoring during undergraduate studies leaves many underrepresented minority (URM) students unprepared to apply to competitive graduate programs. As a part of our ongoing effort to increase the pipeline for the development and training of successful URM scientists in biomedical sciences with focus on reducing cancer health disparities, the Florida-California Cancer Research Education and Engagement (CaRE2) Health Equity Center was launched in 2018. Funded through an NIH/NCI U54 grant mechanism, the CaRE2 Center is a triad partnership among Florida Agricultural and Mechanical University (FAMU), a minority-serving institution, University of Florida (UF), and University of Southern California (USC) Cancer Center. One of the objectives of the triad partnership is to promote the coordination and implementation of the training of the next generation of Black and Latinx biomedical scientists in Florida and California. An important component of the CaRE2 program is the Research and Education Core (REC) designed to coordinate the training of URM students and researchers at different levels in their academic and professional developments. The undergraduate cancer research training program under FAMU-CaRE2 Center is a 3-year (2018-2021) project to identify, train, mentor, and provide the URM undergraduate students with the support network they need to flourish in the program and beyond. In its year-1 funding cycle, the program has made significant progress in developing a novel framework for an undergraduate cancer research education and engagement program at FAMU, one of the forefront minority institutions in the nation. The mentored research program is complemented with professional development and engagement activities, including cancer research seminars, workshops, and community outreach activities. The purpose of this paper is to discuss the strategies implemented for an effective partnership, the leadership and mentoring skills, and outcomes from the year-1 experiences. In addition, we present the progress made in advancing the pool of underrepresented minority students with scientific and academic career progression paths focused on cancer health disparities.
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Affiliation(s)
- Bereket Mochona
- College of Science and Technology, Florida A&M University, Tallahassee, FL, 32307, USA.
| | - Debra Lyon
- College of Nursing, University of Florida, Gainesville, FL, 32611, USA
| | - Ite A Offringa
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Kinfe K Redda
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Renee R Reams
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL, 32307, USA
| | - Folakemi Odedina
- College of Pharmacy and College of Medicine, University of Florida Research and Academic Center, Lake Nona, FL, 32827, USA
| | - Diana J Wilkie
- College of Nursing, University of Florida, Gainesville, FL, 32611, USA
| | - Mariana C Stern
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - John D Carpten
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
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Mochona B, Lyon D, Offringa IA, Redda KK, Reams RR, Odedina F, Wilkie DJ, Carpten JD, Stern MC. Abstract D076: Florida-California Cancer Health Disparity Research, Education & Engagement (CaRE2) Center: Research education overview and preliminary results. Cancer Epidemiol Biomarkers Prev 2020. [DOI: 10.1158/1538-7755.disp19-d076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Abstract
Introduction: Florida Agricultural & Mechanical University (FAMU), University of Florida (UF) and University of Southern California (USC) have partnered to build a strong pathway to workforce diversity in Florida and California. Combined, the three institutions have unique expertise to support research education for Black and Latino students. FAMU (a minority serving institution) has a demonstrated track record of enrolling Under-Represented Minority (URM) students and preparing them as outstanding graduates who go on to pursue PhD degrees in biomedical and behavioral sciences. Hence, FAMU provides a unique environment for the development and testing of this triad partnership program. UF is a top world leader in interdisciplinary research and is one of only a few institutions with an academic health center having six health-related colleges. The UF’s multidisciplinary centers and institutes are designed to create synergies and collaborative research opportunities that focus on the translational nature of biomedical research, following the continuum from fundamental research to clinical research to patient care. USC, located in the multicultural city of Los Angeles, has a highly diverse student body, with 20% of the student population comprised of Black and Hispanic/Latino students. The USC Norris Comprehensive Cancer Center (NCCC) is a major regional and national resource for cancer research, treatment, prevention, and education. Collectively, the three institutions investigate the complex origins and progression of cancer, develop prevention strategies, and search for cures. Methodology and Results: Preliminary results from the first year, which included multiple URM trainees: (thirteen undergraduate, one postbaccalaureate, eight graduate, seven postdoctoral fellows and twelve early-stage investigators), suggested that participation in CaRE2 program is a positive professional development experience, leading to acquisition of research skills in interdisciplinary cancer research, knowledge about cancer health disparities, building of personal and professional networks, and exposure to career opportunities in cancer through interaction with peers, mentors and NCI personnel. Conclusion: The CaRE2 Program appears to enhances the trainees’ motivation for a career in cancer research and may lead to the development of a more diverse workforce to address cancer health disparities. The CaRE2 program is funded by the National Cancer Institute (NCI) of the National Institutes of Health (NIH) through the grant of NIH/NCI1U54CA233396, 1U54CA23344 and 1U54CA23346.
Citation Format: Bereket Mochona, Debra Lyon, Ite A. Offringa, Kinfe K. Redda, Renee R. Reams, Folakemi Odedina, Diana J. Wilkie, John D. Carpten, Mariana C. Stern. Florida-California Cancer Health Disparity Research, Education & Engagement (CaRE2) Center: Research education overview and preliminary results [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D076.
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Affiliation(s)
| | - Debra Lyon
- 2University of Florida, Gainesville, FL, USA,
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Odedina FT, Reams RR, Kaninjing E, Nguyen J, Mochona B, Lyon DE, Askins N, Behar-Horenstein LS. Increasing the Representation of Minority Students in the Biomedical Workforce: the ReTOOL Program. J Cancer Educ 2019; 34:577-583. [PMID: 29542061 PMCID: PMC7247618 DOI: 10.1007/s13187-018-1344-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
With the growing burden of cancer in minority populations and limited progress in eliminating cancer disparities, it has become important to develop a diverse oncology workforce in basic, clinical, and behavioral research who will address cancer disparities and increase the participation of minority populations in clinical trials. To address the lack of well-trained underrepresented minority cancer scientists in Florida, the University of Florida collaborated with Florida A&M University in 2012 to establish the Florida Prostate Cancer Research Training Opportunities for Outstanding Leaders (ReTOOL) Program. Since 2012, the ReTOOL program has expanded to (1) cover all areas of cancer disparities; (2) offer training opportunities to minority students from all historically Black colleges and universities (HBCUs) in Florida; and (3) successfully secure both intramural and extramural federal funding to continuously provide research training opportunities for minority students in Florida. Focusing primarily on training Black students, the ReTOOL model includes culturally sensitive recruitment, mentorship, didactic curriculum, networking, and hands on experience in cancer research. This paper discusses the lessons learned from administering the ReTOOL program for 5 years, which includes having the right inputs (such as majority-minority institutions partnership, funding, faculty advisors, committed mentors, culturally competent staff, and standardized program requirements) and processes (such as pipeline approach, structured applications system, didactic curriculum, research experience, and continuous mentoring) for an effective research training program. The program impact is an increase in the pool of underrepresented minority candidates with scientific and academic career progression paths focused on reducing cancer health disparities.
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Affiliation(s)
- Folakemi T Odedina
- College of Pharmacy, University of Florida, Orlando, FL, USA.
- College of Medicine, University of Florida, Gainesville, FL, USA.
| | - R R Reams
- Florida A&M University, Tallahassee, FL, USA
| | - E Kaninjing
- College of Pharmacy, University of Florida, Orlando, FL, USA
| | - J Nguyen
- College of Pharmacy, University of Florida, Orlando, FL, USA
| | - B Mochona
- Florida A&M University, Tallahassee, FL, USA
| | - D E Lyon
- College of Nursing, University of Florida, Gainesville, FL, USA
| | - N Askins
- College of Pharmacy, University of Florida, Orlando, FL, USA
| | - L S Behar-Horenstein
- Colleges of Dentistry, University of Florida, Gainesville, FL, USA
- College of Education, University of Florida, Gainesville, FL, USA
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Mendonca P, Taka E, Bauer D, Reams RR, Soliman KFA. The attenuating effects of 1,2,3,4,6 penta-O-galloyl-β-d-glucose on pro-inflammatory responses of LPS/IFNγ-activated BV-2 microglial cells through NFƙB and MAPK signaling pathways. J Neuroimmunol 2018; 324:43-53. [PMID: 30236786 DOI: 10.1016/j.jneuroim.2018.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2018] [Revised: 08/28/2018] [Accepted: 09/10/2018] [Indexed: 12/14/2022]
Abstract
BACKGROUND Overactivated microglial cells exhibit chronic inflammatory response and can lead to the continuous production of pro-inflammatory cytokines, perpetuating inflammation, and ultimately resulting in neuronal injury. 1,2,3,4,6-Penta-O-Galloyl-β-d-Glucose (PGG), which is a naturally occurring polyphenolic compound, has exhibited anti-inflammatory effect through the inhibition of many cytokines in different experimental models, but its effect on activated microglia cells was never described. In the present study, we investigated PGG effect in proteins involved in the NFƙB and MAPK signaling pathways, which play a central role in inflammation through their ability to induce transcription of pro-inflammatory genes. METHODS PCR arrays and RT-PCR with individual primers were used to determine the effect of PGG on mRNA expression of genes involved in NFƙB and MAPK signaling pathways. Western blots were performed to confirm PCR results. RESULTS The data obtained showed that PGG modulated the expression of 5 genes from the NFƙB (BIRC3, CHUK, IRAK1, NFƙB1, NOD1) and 2 genes from MAPK signaling pathway (CDK2 and MYC) when tested in RT-PCR assays. Western blots confirmed the PCR results at the protein level, showing that PGG attenuated the expression of total and phosphorylated proteins (CDK2, CHUK, IRAK1, and NFƙB1) involved in NFƙB and MAPK signaling. CONCLUSION These findings show that PGG could modulate the expression of genes and proteins involved in the production of pro-inflammatory cytokines in microglia cells.
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Affiliation(s)
- Patricia Mendonca
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, United States
| | - Equar Taka
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, United States
| | - David Bauer
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, United States
| | - Renee R Reams
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, United States
| | - Karam F A Soliman
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, United States.
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Taka E, Reams RR, Heiman AS, Soliman K, Darling‐Reed SF. Manganese modulates genes involved in regulation of cell cycle. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.1231.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Equar Taka
- College of PharmacyFlorida A & M UniversityTallahasseeFL
| | - Renee R Reams
- College of PharmacyFlorida A & M UniversityTallahasseeFL
| | - Ann S Heiman
- College of PharmacyFlorida A & M UniversityTallahasseeFL
| | - Karam Soliman
- College of PharmacyFlorida A & M UniversityTallahasseeFL
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Mazzio EA, Reams RR, Soliman KFA. The role of oxidative stress, impaired glycolysis and mitochondrial respiratory redox failure in the cytotoxic effects of 6-hydroxydopamine in vitro. Brain Res 2004; 1004:29-44. [PMID: 15033417 DOI: 10.1016/j.brainres.2003.12.034] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2003] [Indexed: 11/16/2022]
Abstract
The neurotoxin, 6-hydroxydopamine (6-OHDA) has been implicated in the neurodegenerative process of Parkinson's disease. The current study was designed to elucidate the toxicological effects of 6-OHDA on energy metabolism in neuroblastoma (N-2A) cells. The toxicity of 6-OHDA corresponds to the total collapse of anaerobic/aerobic cell function, unlike other mitochondrial toxins such as MPP+ that target specific loss of aerobic metabolism. The toxicity of 6-OHDA paralleled the loss of mitochondrial oxygen (O2) consumption (MOC), glycolytic activity, ATP, H+ ion gradients, membrane potential and accumulation of the autoxidative product, hydrogen peroxide (H2O2). Removing H2O2 with nonenzymatic stoichiometric scavengers, such as carboxylic acids, glutathione and catalase yielded partial protection. The rapid removal of H2O2 with pyruvate or catalase restored only anaerobic glycolysis, but did not reverse the loss of MOC, indicating mitochondrial impairment is independent of H2O2. The H2O2 generated by 6-OHDA contributed toward the loss of anaerobic glycolysis through lipid peroxidation and lactic acid dehydrogenase inhibition. The ability of 6-OHDA to maintain oxidized cytochrome c (CYT-C-OX) in its reduced form (CYT-C-RED), appears to play a role in mitohondrial impairment. The reduction of CYT-C by 6-OHDA, was extensive, occurred within minutes, preceded formation of H2O2 and was unaffected by catalase or superoxide dismutase. At similar concentrations, 6-OHDA readily altered the valence state of iron [Fe(III)] to Fe(II), which would also theoretically sustain CYT-C in its reduced form. In isolated mitochondria, 6-OHDA had negligible effects on complex I, inhibited complex II and interfered with complex III by maintaining the substrate, CYT-C in a reduced state. 6-OHDA caused a transient and potent surge in isolated cytochrome oxidase (complex IV) activity, with rapid recovery as a result of 6-OHDA recycling CYT-C-OX to CYT-C-RED. Typical mitochondrial toxins such as MPP+, azide and antimycin appeared to inhibit the catalytic activity of ETC enzymes. In contrast, 6-OHDA alters the redox of the cytochromes, resulting in loss of substrate availability and obstruction of oxidation-reduction events. Complete cytoprotection against 6-OHDA toxicity and restored MOC was achieved by combining catalase with CYT-C (horse heart). In summary, CYT-C reducing properties are unique to catecholamine neurotransmitters, and may play a significant role in selective vulnerability of dopaminergic neurons to mitochondrial insults.
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Affiliation(s)
- Elizabeth A Mazzio
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, USA
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Choi SJ, Mazzio EA, Reams RR, Soliman KF. Gestational cocaine exposure alters postnatal pituitary-adrenal axis activity and stress endurance in rats. Ann N Y Acad Sci 1998; 844:336-45. [PMID: 9668691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Female pregnant Sprague-Dawley rats were injected once daily with 40 mg/kg cocaine hydrochloride or 0.9% saline from gestational day 12 (GD 12) to GD 21. From postnatal day 21 (PND 21) to PND 60, both male and female offspring were examined for stress response. Treated male and female offspring demonstrated a diminished tolerance to stress as determined by a cold water stress test performed at PND 21, 30 and 40. Base hormonal levels of adrenocorticotropin hormone (ACTH) and corticosterone were not affected by prenatal cocaine exposure in male offspring at PND 30. However, immobilization for 1 hr caused a significant sustained elevation of corticosterone levels at both PND 30 and PND 60 in male treated offspring as compared to the control group. Plasma ACTH levels were also significantly sustained after 1 hr of immobilization at PND 60 for the cocaine-treated male offspring. These results indicate both a diminished capacity to respond to stress and an abnormal heightened reactivity of the pituitary-adrenal axis in offspring exposed to cocaine in utero.
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Affiliation(s)
- S J Choi
- College of Pharmacy and Pharmaceutical Sciences, Florida A & M University, Tallahassee 32307, USA
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Abstract
The effects of Selenium (Se) on central dopaminergic function were examined in male Sprague-Dawley rats. In this experiment, animals were implanted with microdialysis probes and dialysates were analyzed for dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA). After reaching baseline values, sodium selenite was either injected intraperitoneally (i.p.) or directly infused into the striatum (ST) or nucleus accumbens (NA). Se administration of 3.0 mg/kg (i.p.) significantly increased (70%) DA overflow in the ST. Meanwhile direct Se perfusion (10 mM) also caused a significant elevation of synaptic DA concentrations in the ST and NA. Levels of DOPAC and HVA were minimally affected in all studies. In order to test for the effects of DA receptor activation, animals were pretreated with quinpirole (0.5 mg/kg, s.c.), an hour prior to Se (10 mM) infusion through the probe. It was found that quinpirole pre-treatment reduced Se-induced changes in DA concentrations. It was concluded from the present study that Se's central action might be related to its ability to potentiate DA function.
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Affiliation(s)
- H R Rasekh
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee 32307, USA
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Soliman KF, Reams RR, Udoye MO, Nonavinakere VK. Inhibition of the rat adrenal ornithine decarboxylase activity by immobilization stress and/or dexamethasone. Life Sci 1997; 60:2383-7. [PMID: 9199482 DOI: 10.1016/s0024-3205(97)00298-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effects of immobilization stress and/or dexamethasone (DEX) on the adrenal ornithine decarboxylase (ODC) activities of sham-operated and adrenal-medulloectomized (enucleated) male Sprague-Dawley rats were investigated. On day 11 after surgery, rats were injected with saline or DEX (1 mg/kg), 3 h before the time of sacrifice (0600 h or 1800 h). Four groups, from sham-operated and enucleated rats (ENU) treated with saline or DEX were subjected to immobilization stress for 1 h prior to sacrifice. Groups of rats from stress-sham-DEX, non stress-sham-DEX, stress-sham, non stress-sham, stress-ENU-DEX, non stress-ENU-DEX, stress-ENU, and non stress-ENU were sacrificed at 0600 h or 1800 h on day 11 after surgery. Adrenal glands were excised and later analyzed for ODC activities. Results indicated that DEX and/or immobilization stress inhibited ODC activities (p<0.05) in normal and regenerating adrenal glands at 1800 h and ODC activity varies diurnally, the activity being greater at 1800 h than at 0600 hours (p<0.001).
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Affiliation(s)
- K F Soliman
- Florida A&M University College of Pharmacy and Pharmaceutical Sciences, Tallahassee 32307, USA
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Lewis EA, Reams RR. Histone H1: ultracentrifugation studies of the effects of ionic strength and denaturants on the solution conformation. Arch Biochem Biophys 1983; 223:185-92. [PMID: 6859856 DOI: 10.1016/0003-9861(83)90584-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The conformation of histone H1 has been examined under native and denaturing conditions in the absence of DNA or chromatin. Sedimentation coefficients were determined for Histone H1 in 0.1 M KCl and in 6 M guanidine hydrochloride solutions at pH 7.4. The influence of ionic strength on the conformation of histone H1 has been determined by measurement of the sedimentation coefficient in tetramethylammonium chloride solutions of up to 2.5 M and extrapolated to infinite ionic strength. Results from these experiments suggest that the native conformation of histone H1 is very asymmetric in shape. The molecule is best described as a prolate ellipsoid with axes of 312 A (2a) and 16 A (2b) in low ionic strength media and also as a prolate ellipsoid with axes of 202 A (2a) and 20 A (2b) at high ionic strength or when associated with polyanions, e.g., DNA. Denaturation of histone H1 by guanidine hydrochloride was found to be completely reversible. In 6 M guanidine hydrochloride, the H1 molecule collapses to a sphere but the original extended conformation of the protein is readily restored on dialysis. This suggests rigid conformational requirements for the H1 molecule as incorporated into chromatin. The shape and dimensions for the H1 molecule at high ionic strength are not sufficiently conclusive to locate H1 in the chromatin structure. It is proposed, however, that viable models for chromatin architecture must be consistent with the histone H1 solution dimensions obtained here.
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