• 8-Cl-Adenosine enhances 1,25-dihydroxyvitamin D3-induced growth inhibition without affecting 1,25-dihydroxyvitamin D3-stimulated differentiation of primary mouse epidermal keratinocytes.

      Bollag, Wendy B; Zhong, Xiaofeng; Josephson, Sarah; Department of Medicine; Department of Cellular Biology and Anatomy; Institute of Molecular Medicine and Genetics (2004-08-10)
      BACKGROUND: Epidermal keratinocytes continuously proliferate and differentiate to form the mechanical and water permeability barrier that makes terrestrial life possible. In certain skin diseases, these processes become dysregulated, resulting in abnormal barrier formation. In particular, skin diseases such as psoriasis, actinic keratosis and basal and squamous cell carcinomas are characterized by hyperproliferation and aberrant or absent differentiation of epidermal keratinocytes. We previously demonstrated that 8-Cl-adenosine (8-Cl-Ado) can induce keratinocyte growth arrest without inducing differentiation. RESULTS: To determine if this agent might be useful in treating hyperproliferative skin disorders, we investigated whether 8-Cl-Ado could enhance the ability of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], a known keratinocyte differentiating agent and a clinical treatment for psoriasis, to inhibit keratinocyte growth. We found that low concentrations of 8-Cl-Ado and 1,25(OH)2D3 appeared to act additively to reduce proliferation of primary mouse epidermal keratinocytes. However, another agent (transforming growth factor-beta) that triggers growth arrest without inducing differentiation also coincidentally inhibits differentiation elicited by other agents; inhibition of differentiation is suboptimal for treating skin disorders, as differentiation is often already reduced. Thus, we determined whether 8-Cl-Ado also decreased keratinocyte differentiation induced by 1,25(OH)2D3, as measured using the early and late differentiation markers, keratin 1 protein levels and transglutaminase activity, respectively. 8-Cl-Ado did not affect 1,25(OH)2D3-stimulated keratin 1 protein expression or transglutaminase activity. CONCLUSIONS: Our results suggest that 8-Cl-Ado might be useful in combination with differentiating agents for the treatment of hyperproliferative disorders of the skin.
    • 96 plays a role in the virulence of C. jejuni

      Rathbun, Kimberly M; Department of Medicine (2009-05)
      Campylobacter jejuni is a gastrointestinal pathogen of humans but part of the normal flora of poultry. C. jejuni therefore grows well at both 37°C and 42°C. Proteomic studies on temperature regulation in C. jejuni strain 81-176 revealed the upregulation at 37°C of CJ0596, a predicted periplasmic chaperone that is similar to proteins found to be involved in outer membrane protein (OMP) folding and virulence in other bacteria. The cj0596 gene was highly conserved in multiple strains and species of Campylobacter (24 in total), implying the importance of this gene. To study the role CJ0596 plays in Campylobacter pathogenesis, a mutant derivative of strain 81-176 was constructed in which the cj0596 gene was precisely deleted. This mutant was complemented by restoring the gene to its original chromosomal location. The mutant strain demonstrated a decreased growth rate and lower final growth yield, yet was more motile than wild-type. The cj0596 mutant also showed altered levels of several outer membrane proteins (OMPs), and changes in membrane-associated characteristics (antimicrobial sensitivity, autoagglutination, and biofilm formation). In either single or mixed infections, the mutant was less able to colonize mice than wild-type. Purified, recombinant CJ0596 had peptidyl-prolyl cistrans isomerase (PPIase) activitty, but did not functionally complement an E. coli surA mutant. These results suggest that C. jejuni CJ0596 is a PPIase and loss of CJ0596 alters phenotypes that have been shown to be related to the pathogenesis of the bacterium.
    • Accelerated Growth Plate Mineralization and Foreshortened Proximal Limb Bones in Fetuin-A Knockout Mice

      Seto, Jong; Busse, Bjorn; Gupta, Himadri S.; Schafer, Cora; Krauss, Stefanie; Dunlop, John W. C.; Masic, Admir; Kerschnitzki, Michael; Zaslansky, Paul; Boesecke, Peter; et al. (2012-10-16)
      The plasma protein fetuin-A/alpha2-HS-glycoprotein (genetic symbol Ahsg) is a systemic inhibitor of extraskeletal mineralization, which is best underscored by the excessive mineral deposition found in various tissues of fetuin-A deficient mice on the calcification-prone genetic background DBA/2. Fetuin-A is known to accumulate in the bone matrix thus an effect of fetuin-A on skeletal mineralization is expected. We examined the bones of fetuin-A deficient mice maintained on a C57BL/6 genetic background to avoid bone disease secondary to renal calcification. Here, we show that fetuin-A deficient mice display normal trabecular bone mass in the spine, but increased cortical thickness in the femur. Bone material properties, as well as mineral and collagen characteristics of cortical bone were unaffected by the absence of fetuin-A. In contrast, the long bones especially proximal limb bones were severely stunted in fetuin-A deficient mice compared to wildtype littermates, resulting in increased biomechanical stability of fetuin-A deficient femora in three-point-bending tests. Elevated backscattered electron signal intensities reflected an increased mineral content in the growth plates of fetuin-A deficient long bones, corroborating its physiological role as an inhibitor of excessive mineralization in the growth plate cartilage matrix - a site of vigorous physiological mineralization. We show that in the case of fetuin-A deficiency, active mineralization inhibition is a necessity for proper long bone growth.
    • ADIPOSE HDAC9 DELETION PROTECT AGAINST DIET INDUCED OBESITY IN MICE THROUGH REGULATING ENERGY EXPENDITURE

      Hassan, Nazeera; Zarzour, Abdalrahman; Department of Biological Sciences; Department of Medicine; College of Allied Health Sciences; Kim, Ha Won; Weintraub, Neal; Augusta University (2019-02-13)
      Our group has previously identified histone deacetylase 9 (HDAC9) as a regulator of adipocyte differentiation, and its expression levels were elevated in diet induced obese (DIO) mice.� We also reported that global HDAC9 deletion protected mice against DIO through promoting beige adipogenesis. Here, we hypothesized that adipose HDAC9 correlate with human obesity similar to murine models, and its deletion is sufficient to protect against DIO. To test this hypothesis we crossed HDAC9 floxed mice with adiponectin-cre mice to generate adipose-specific HDAC9 knockout mice (AdipCre-HDAC9), which exhibited 30% less weight gain when fed high fat diet compared to control despite increased food intake, in association with increased energy combustion & O2 consumption, improved insulin sensitivity and glucose tolerance. However, unlike global HDAC9 deletion, this was not associated with increased beige adipogenesis nor increase in brown adipose tissue function. Interestingly, AdipoCre-HDAC9 mice fed normal chow diet didn�t exhibit altered energy expenditure nor weight differences when compared to littermate controls. These finding suggest that adipose HDAC9 regulate energy expenditure in response to high fat diet and can be a promising therapeutic target to combat obesity.
    • Anomalous coronary artery found in the syncopal workup of an elderly man

      Oommen, Ronnie; Wilkins, Thad; Chen, Stephen Y; Arora, Vishal; Department of Family Medicine; Department of Medicine; Department of Cardiology (2012-07)
      Syncope, defined as a transient loss of consciousness, is seen in 1% of all visits to emergency departments and urgent care clinics in the United States. Syncope is categorized as cardiogenic, neurologic, or psychogenic. Anomalies of the coronary arteries are rare, and anomalous coronary arteries present as syncope more often in the young than in the elderly; syncope rarely occurs in patients 65 years of age and older. There are 2 major variants of coronary anomalies. In the first variant, the left main coronary artery arises from the right aortic sinus. In the second variant, the right coronary artery arises from the left aortic sinus. The risk of sudden death is higher in patients with the left coronary artery arising from the right aortic sinus. We present a case of an anomalous coronary artery discovered during the syncopal workup in a 66-year-old man because no such cases have been published in the United States. We will discuss the management of anomalous coronary arteries as well as a systematic approach to the diagnosis and management of syncope.
    • Association between Genetic Variants in DNA and Histone Methylation and Telomere Length

      Kim, Sangmi; Parks, Christine G.; Xu, Zongli; Carswell, Gleta; DeRoo, Lisa A.; Sandler, Dale P.; Taylor, Jack A.; Department of Medicine (2012-07-11)
      Telomere length, a biomarker of aging and age-related diseases, exhibits wide variation between individuals. Common genetic variation may explain some of the individual differences in telomere length. To date, however, only a few genetic variants have been identified in the previous genome-wide association studies. As emerging data suggest epigenetic regulation of telomere length, we investigated 72 single nucleotide polymorphisms (SNPs) in 46 genes that involve DNA and histone methylation as well as telomerase and telomere-binding proteins and DNA damage response. Genotyping and quantification of telomere length were performed in blood samples from 989 non-Hispanic white participants of the Sister Study, a prospective cohort of women aged 35–74 years. The association of each SNP with logarithmically-transformed relative telomere length was estimated using multivariate linear regression. Six SNPs were associated with relative telomere length in blood cells with p-values<0.05 (uncorrected for multiple comparisons). The minor alleles of BHMT rs3733890 G>A (p = 0.041), MTRR rs2966952 C>T (p = 0.002) and EHMT2 rs558702 G>A (p = 0.008) were associated with shorter telomeres, while minor alleles of ATM rs1801516 G>A (p = 0.031), MTR rs1805087 A>G (p = 0.038) and PRMT8 rs12299470 G>A (p = 0.019) were associated with longer telomeres. Five of these SNPs are located in genes coding for proteins involved in DNA and histone methylation. Our results are consistent with recent findings that chromatin structure is epigenetically regulated and may influence the genomic integrity of telomeric region and telomere length maintenance. Larger studies with greater coverage of the genes implicated in DNA methylation and histone modifications are warranted to replicate these findings.
    • Asymptomatic Severe Hypocalcemia Secondary to Vitamin D Deficiency in an Elderly Patient

      Aldasouqi, Saleh; Glassy, Crystal M.; Glassy, Matthew S.; Treska, Anxhela; Caldwell-McMillan, Molly; Gossain, Ved; Department of Medicine (2011-11-2)
    • Can novel Apo A-I polymorphisms be responsible for low HDL in South Asian immigrants?

      Dodani, Sunita; Dong, Yanbin; Zhu, Haidong; George, Varghese; Department of Medicine (2010-03-19)
      Coronary artery disease (CAD) is the leading cause of death in the world. Even though its rates have decreased worldwide over the past 30 years, event rates are still high in South Asians. South Asians are known to have low high-density lipoprotein (HDL) levels. The objective of this study was to identify Apolipoprotein A-I (Apo A-I) polymorphisms, the main protein component of HDL and explore its association with low HDL levels in South Asians. A pilot study on 30 South Asians was conducted and 12-h fasting samples for C-reactive protein, total cholesterol, HDL, low-density lipoprotein (LDL), triglycerides, Lipoprotein (a), Insulin, glucose levels, DNA extraction, and sequencing of Apo A-I gene were done. DNA sequencing revealed six novel Apo A-I single nucleotide polymorphisms (SNPs) in South Asians, one of which (rs 35293760, C938T) was significantly associated with low (<40 mg/dl) HDL levels (P = 0.004). The association was also seen with total cholesterol (P = 0.026) and LDL levels (P = 0.032). This pilot work has highlighted some of the gene-environment associations that could be responsible for low HDL and may be excess CAD in South Asians. Further larger studies are required to explore and uncover these associations that could be responsible for excess CAD risk in South Asians.
    • Carcinomatous Meningitis: The Natural History of Successfully Treated Metastatic Bladder Cancer

      Tadepalli, S.; Coleman, Teresa; Hackett, Ladawn A.; Liles, G.B.; Department of Medicine; Department of Pathology (2011-08-24)
      Carcinomatous meningitis due to bladder cancer is a rare entity reported only in case reports. Optimal therapy is thus poorly defined with earlier cases reporting an unsuccessful outcome. Here we report a case of late carcinomatous meningitis secondary to transitional cell carcinoma (TCC) of the bladder occurring in a patient in complete remission. He was successfully treated with intrathecal methotrexate and whole brain irradiation and experienced prolonged survival after treatment. With modern chemotherapy increasing complete remissions and survival rates in patients with TCC, more and more patients are being reported with carcinomatous meningitis. We raise the question of whether central nervous system prophylaxis should be considered in patients with TCC achieving a complete remission to chemotherapy in the metastatic setting.
    • Diagnosis and management of upper gastrointestinal bleeding.

      Wilkins, Thad; Khan, Naiman; Nabh, Akash; Schade, Robert R.; Department of Family Medicine; Department of Medicine (2012-03-01)
      Upper gastrointestinal bleeding causes significant morbidity and mortality in the United States, and has been associated with increasing nonsteroidal anti-inflammatory drug use and the high prevalence of Helicobacter pylori infection in patients with peptic ulcer bleeding. Rapid assessment and resuscitation should precede the diagnostic evaluation in unstable patients with severe bleeding. Risk stratification is based on clinical assessment and endoscopic findings. Early upper endoscopy (within 24 hours of presentation) is recommended in most patients because it confirms the diagnosis and allows for targeted endoscopic treatment, including epinephrine injection, thermocoagulation, application of clips, and banding. Endoscopic therapy results in reduced morbidity, hospital stays, risk of recurrent bleeding, and need for surgery. Although administration of proton pump inhibitors does not decrease mortality, risk of rebleeding, or need for surgery, it reduces stigmata of recent hemorrhage and the need for endoscopic therapy. Despite successful endoscopic therapy, rebleeding can occur in 10 to 20 percent of patients; a second attempt at endoscopic therapy is recommended in these patients. Arteriography with embolization or surgery may be needed if there is persistent and severe bleeding.
    • The effect of student training on accuracy of completion of death certificates.

      Degani, Adil T; Patel, Rajendrakumar M; Smith, Betsy E; Grimsley, Edwin; Section of Pulmonary & Critical Care Medicine, Department of Medicine, Medical College of Georgia (2010-02-18)
      BACKGROUND: Death certificates are an invaluable source of statistical and medical information, as well as important legal documents. However, few physicians receive formal training on how to accurately complete them. PURPOSE: To determine if a simple intervention can improve the accuracy of death certificate completion by medical students. METHODS: Participants included all third year medical students undergoing their core Internal Medicine rotation at Mercer University School of Medicine at the Medical Center of Central Georgia. Participation was voluntary and participants completed an approved informed consent. Students were presented a tutorial from the National Association of Medical Examiners website. They were asked to complete a death certificate both before and after the tutorial along with subjective questionnaires. The primary outcome measurement was the difference in scores pre- and post-tutorial. RESULTS: The mean score before the tutorial was 11.75 (+/-3.20) and the mean score post-tutorial was 18.85 (+/-2.56), indicating an increase in scores. The mean difference in pre- and post-tutorial scores was significant (t = 20.39, p < 0.0001). CONCLUSIONS: We found that using a tutorial to teach students how to correctly complete a death certificate was effective.
    • Excess coronary artery disease risk in South Asian immigrants: can dysfunctional high-density lipoprotein explain increased risk?

      Dodani, Sunita; Department of Medicine (2009-02-02)
      BACKGROUND: Coronary artery disease (CAD) is the leading cause of mortality and morbidity in the United States (US), and South Asian immigrants (SAIs) have a higher risk of CAD compared to Caucasians. Traditional risk factors may not completely explain high risk, and some of the unknown risk factors need to be explored. This short review is mainly focused on the possible role of dysfunctional high-density lipoprotein (HDL) in causing CAD and presents an overview of available literature on dysfunctional HDL. DISCUSSION: The conventional risk factors, insulin resistance parameters, and metabolic syndrome, although important in predicting CAD risk, may not sufficiently predict risk in SAIs. HDL has antioxidant, antiinflammatory, and antithrombotic properties that contribute to its function as an antiatherogenic agent. Recent Caucasian studies have shown HDL is not only ineffective as an antioxidant but, paradoxically, appears to be prooxidant, and has been found to be associated with CAD. Several causes have been hypothesized for HDL to become dysfunctional, including Apo lipoprotein A-I (Apo A-I) polymorphisms. New risk factors and markers like dysfunctional HDL and genetic polymorphisms may be associated with CAD. CONCLUSIONS: More research is required in SAIs to explore associations with CAD and to enhance early detection and prevention of CAD in this high risk group.
    • Hydrogen peroxide improves the visibility of ulcer bases in acute non-variceal upper gastrointestinal bleeding: a single-center prospective study.

      Sridhar, Subbaramiah; Chamberlain, Sherman; Thiruvaiyaru, Dharma; Sethuraman, Sankara; Patel, Jigneshkumar; Schubert, Moonkyung; Cuartas-Hoyos, Francisco; Schade, Robert R.; Department of Medicine (2009-10-19)
      BACKGROUND: Acute non-variceal upper gastrointestinal bleeding (ANVB) or hemorrhage (used interchangeably) is an emergency. Endoscopically applied hydrogen peroxide (H2O2) has been shown to improve visualization of the ulcer base. AIMS: To test the hypothesis that ulcer base clot clearance with 3% H2O2 improves the visualization of ANVB lesions compared to water alone. METHODS: In this single-center prospective study, 320 patients with ANVB were examined, of which 81 met the entry criteria for evaluation. All patients with ANVB underwent urgent endoscopy. Those with adherent clots on the ulcer base were sprayed with 250 ml of water, followed by up to 100 ml of 3% H2O2. The main outcome measurement was Kalloo"s Visual Scores of the ulcer base before and after water and H2O2. RESULTS: Eighty-one patients with gastric ulcers (GU; 34) and duodenal ulcers (DU; 47) met the entry criteria. The mean improvement in grade from water to H2O2 was 2.04 (95% confidence interval [CI] (1.86, 2.23)). The mean volume of H2O2 used to clear clots was higher (70 ml) in patients who were negative for both Helicobacter pylori and non-steroidal anti-inflammatory drug (NSAID) use than in those who were positive for both (31 ml) (P = 0.00). More DU patients (72%) had visible vessels than GU patients (44%) (P = 0.01). CONCLUSIONS: H2O2 improved the visualization of ulcer bases in ANVB. A smaller volume of H2O2 was required to clear clots in patients who used NSAIDs and had H. pylori infection. H2O2 identified more DU vessels. The use of H2O2 should be considered as a standard therapy in the management of clots in ANVB.
    • Impact of clinical pharmacy services on renal transplant recipients' adherence and outcomes.

      Chisholm-Burns, Marie A; Spivey, Christina A; Garrett, Charlene; McGinty, Herbert; Mulloy, Laura L; Department of Medicine (2009-11-20)
      The purpose of this article is to provide a description of a clinical pharmacy services program implemented in a renal transplant clinic to improve medication access and adherence as well as health and economic outcomes among renal transplant recipients (RTRs). Following a team-based planning process and an informal survey of RTRs, a clinical pharmacy service intervention was implemented in the Medical College of Georgia renal transplant clinic. As part of the intervention, a clinical pharmacist reviewed and optimized medication therapy, provided instructions on how to take medication, and assisted with enrollment into medication assistance programs. Significant differences were found between RTRs who did and did not receive clinical pharmacy services on measures of adherence, health, economics, and quality of life. Clinical pharmacy services, as described in this article, have a positive impact on renal transplant recipients' medication adherence, health and economic outcomes, and health-related quality of life. The findings described here suggest that clinical pharmacy services are a viable and effective option for improving care for RTRs in an outpatient clinic setting.
    • Improved Immunodetection of Endogenous α-Synuclein

      Lee, Byung Rho; Kamitani, Tetsu; Department of Medicine; Center for Molecular Chaperone/Radiobiology & Cancer Virology (2011-08-19)
      α-Synuclein is a key molecule in understanding the pathogenesis of neurodegenerative α-synucleinopathies such as Parkinson's disease. Despite extensive research, however, its precise function remains unclear partly because of a difficulty in immunoblotting detection of endogenous α-synuclein. This difficulty has largely restricted the progress for α-synucleinopathy research. Here, we report that α-synuclein monomers tend to easily detach from blotted membranes, resulting in no or very poor detection. To prevent this detachment, a mild fixation of blotted membranes with paraformaldehyde was applied to the immunoblotting method. Amazingly, this fixation led to clear and strong detection of endogenous α-synuclein, which has been undetectable by a conventional immunoblotting method. Specifically, we were able to detect endogenous α-synuclein in various human cell lines, including SH-SY5Y, HEK293, HL60, HeLa, K562, A375, and Daoy, and a mouse cell line B16 as well as in several mouse tissues such as the spleen and kidney. Moreover, it should be noted that we could clearly detect endogenous α-synuclein phosphorylated at Ser-129 in several human cell lines. Thus, in some tissues and cultured cells, endogenous α-synuclein becomes easily detectable by simply fixing the blotted membranes. This improved immunoblotting method will allow us to detect previously undetectable endogenous α-synuclein, thereby facilitating α-synuclein research.
    • An Investigation of the Chronic Disease Self-Management Program - Assessing CDSMP Facilitators' Perceptions of the Program's Effect

      Hillman, L. M.; Anderson, C.; Stoodt, G.; Department of Medicine; Augusta University (2017-03)
      Chronic conditions are public health threats. The Chronic Disease Self-Management Program (CDSMP) is an evidence-based disease management program that addresses personal self-management of chronic conditions. The CDSMP involves peer trainers who instruct and assist with chronic disease preventive measures. Although disease management demonstrates promise to improving patient self-maintenance, previous researchers have not evaluated how the program affects program leaders. The purpose of this study was to discover how self-help leaders feel about the CDSM program. The overarching research question asked about perspectives that self-help leaders had toward the program. Through a narrative qualitative approach, the perceptions of peer leaders were examined to determine if the program was personally beneficial. Guided by the social cognitive theory, a purposeful convenience sample of 20 participants completed the study. The participants were practicing peer trainers in the CDSMP prog ram. Data analysis included hand coding using open and axial coding and content analysis. Study findings included themes surrounding how the CDSMP program benefits health in general as well as the management of facilitators’ own chronic diseases, health behaviors, and increased quality of life. The ability for chronic disease management leaders to experience positive effects of the program they administer may result in positive social change. This awareness can positively affect social change by enhancing an already established evidence-based community health program with stronger and better-equipped leaders.
    • Mechanisms of Diet-Induced Hypertension and Vascular Disease Risk in Dahl Rats

      Spradley, Frank T.; Department of Medicine (2011)
      Dahl salt-sensitive (SS) rats are genetically predisposed to cardiovascular-renal disease. These studies examined cardiovascular-renal outcomes in response to a high-fat diet/normal-salt diet in SS rats. In a separate study, we examined cardiovascular-renal disease risk in SS rats on different standard chow diet/normal-salt diets. We tested the hypotheses that: (1) a high-fat diet induces hypertension and renal injury in SS rats; (2) a high-fat diet enhances aortic vasoconstriction in SS rats; (3) a high-fat diet induces aortic perivascular adipose tissue (PVAT) dysfunction in SS rats; and (4) two standard chow diets, namely AIN-76A and Teklad diet, induce differential vasoconstriction or vasorelaxation phenotypes in aorta and small mesenteric arteries from SS rats. In the high-fat diet studies, rats were provided high-fat diet starting at 12 weeks old. At 16 weeks old, SS rats on the high-fat diet had hypertension and greater renal glomerular and tubular injury than SS-13BN rats. SS rats supplemented with the immunosuppressive drug mycophenolate mofetil (MMF; 30 mg/kg/day, oral) for the duration of the high-fat diet did not develop hypertension. High-fat diet was associated with reduced vasoconstrictive response to angiotensin II and increased acetylcholine-mediated vasorelaxation in SS rats via increased nitric oxide synthase (NOS) function in comparison to SS rats maintained on a normal-fat/normal-salt diet. In regards to PVAT function, high-fat diet increased thoracic aorta PVAT deposition and induced PVAT-mediated blunting of aortic vasoconstriction. In the standard chow diet studies, 16-week old SS rats placed on the AIN or Teklad diet at weaning had similar NOS functional regulation of vasoconstriction and vasorelaxation in large and small arteries. However, by using a diet-switch protocol, we demonstrated that SS rats placed on AIN diet at weaning and changed to Teklad diet at 12 weeks old had reduced NOS-mediated vasorelaxation and reduced NOS buffering of vasoconstriction in small arteries from SS rats, which was not observed in the corresponding diet-switch group. In conclusion, these studies highlight differential renal and vascular responses to a short-term high-fat diet, and even changes in standard chow diet, when genetically predisposed to hypertension.
    • Mechanisms of ET-1-mediated 02~ production in the rat aorta

      Loomis, E. D.; Department of Medicine (2004-06)
      The objectives of this project were to test the hj^othesis that in the rat aorta endothelin-I (ET-I) binds to the ETa receptor stimulating superoxide (O2’ ) production. Furthermore, we wanted to identify the mechanism through which ET-1-mediates O2' production. Chemiluminescent detection of O2” production using probes such as lucigenin has been widely used with enzyme systems, leukocytes, and vascular tissues. Our first goal was to develop a microplate high-throughput protocol for lucigeninamplified chemiluminesence detection of 0 2 'L We have developed a novel adaptation to lucigenin-based assays that allows up to 36 samples to be counted at virtually the same time. Recent studies have shown that NOS 3 can become uncoupled and produce O2* when deprived of its cofactor BH4 . In addition several authors have shown that ONOOoxidizes BH4 in vitro. Using the high-throughput lucigenin assay and dihydroethidine (DHE) staining we have shown that (1) ET-1 is able to stimulate 0 2 "^ production in both endothelium-intact and -denuded vessels through the ETA-receptor, (2) ET-1 stimulates O2’ production through both NAD(P)H oxidase and an endothelial source of NOS, and (3) addition of exogenous tetrahydrobiopterin (BH4 ) and inhibition of peroxynitrite (ONOO-) inhibit ET-I-mediated 0 2 *^ production. Therefore our data have led us to hypothesize that ET-I stimulates O2* production by activating NAD(P)H oxidase through the ETa receptor. O2' production by NAD(P)H oxidase leads to the formation of ONOO- and the degradation of BH4. The loss of BH4 leads to uncoupled NOS which then contributes to ET-1-mediated production. In addition, we have found that (1) ET-1 increases the production of interleukin- 6 (IL-6 ) and (2) ET-1-mediated O2' production adversely affects vascular contractility. Although these consequences do not appear to be due to NOS uncoupling, they help support the role of ET-1 in vascular dysfunction.
    • Mild Functional Ischemic Mitral Regurgitation Following Acute Coronary Syndrome: A Retrospective Study

      Pant, Sadip; Neupane, Pritam; Pant, Om Biju; Paudel, Raju; Kumar, M. P. Kavin; Vijayashankar, C. S.; Shrestha, Rajendra Man; Department of Pulmonary and Critical Care (2011-04)
      Background:: Ischemic mitral regurgitation is a frequent complication of acute coronary syndrome. It primarily occurs in patients with a prior myocardial infarction but also may be seen with acute ischemia, a setting in which the MR typically resolves after the ischemia resolves. The vast majority of patients have â functionalâ ischemic MR. In these individuals, the papillary muscles, chordae, and valve leaflets are normal. However, the leaflets do not coapt and restricted leaflet motion is frequently noted on echocardiography. Ischemic mitral regurgitation indicates a poor prognosis after acute myocardial infarction. This study addresses the clinical characteristics of patients of acute coronary syndrome with mild functional ischemic mitral regurgitation and its impact on immediate in-hospital cardiovascular outcomes and death.
    • Novel Nitric Oxide Synthase-Dependent Mechanism of Vasorelaxation in Small Arteries from Hypertensive Rats

      Kang, Kyu-Tae; Department of Medicine (2007-10)
      Endothelial dysfunction in hypertension is associated with impaired endothelium-dependent vasorelaxation, which is consistently observed in conduit vessels. However, the controversial observation of either impaired or intact vasorelaxation of small resistance arteries from hypertensive animals suggests that the mechanism(s) of endothelium-dependent vasorelaxation in small resistance arteries may be different from that observed in conduit vessels under hypertensive condition. Vasorelaxation in small resistance arteries is mediated via multiple pathways including nitric oxide synthase (NOS)-, cyclooxygenase (COX)-, and endothelium-derived hyperpolarizing factor (EDHF)-mediated pathway. Therefore, the overall goal of these studies was to determine the mechanism(s) involving vasorelaxation of small arteries from hypertensive rats. For these studies, normotensive (NORM), angiotensin II-infused (ANG), high salt (HS), ANG high salt (ANG/HS), placebo, and deoxycorticosterone acetate-salt (DOCA) rats were studied. The studies with pharmacological blockade of each pathway demonstrated that the NOS-dependent component was increased to maintain acetylcholine (ACh)-induced vasorelaxation in small mesenteric arteries from hypertensive rats. Furthermore, increased NOS-dependent pathway appears to compensate for the dysfunctional Ca2+-activated K+ channel-sensitive EDHF pathway in small mesenteric arteries from ANG compared to NORM. These results led us to design further experiments to test the hypothesis that both NO and H2O2 serve as NOS-dependent mediators to maintain vasorelaxation in small mesenteric arteries from hypertensive rats. In small arteries from ANG, ACh increased NOS-dependent cGMP production. ACh also increased NOS3 phosphorylation at Ser 633 and decreased phosphorylation at Thr 495. While, NOS3 phosphorylation at Ser 1177 was impaired in response to ACh in ANG, which was accompanied by reduced basal and a less extended ACh-stimulated cGMP production in ANG compared to NORM. To investigate the alteration of signal transduction pathways related to impaired NOS3 phosphorylation at Ser 1177 in response to ACh, Akt phosphorylation at Ser 473 and VASP phosphorylation at Ser 239 were tested. These pathways were not changed by ACh in the small mesenteric arteries from ANG. Our results indicate that the NO/cGMP signaling is present in response to ACh in small mesenteric arteries from ANG, however this signaling pathway-mediating vasorelaxation may be facilitated via neither Akt nor PKG. On the other hand, ACh stimulated L-NAME-sensitive H2O2 production in small mesenteric arteries from ANG, but not NORM. H2O2 induced vasorelaxation and catalase blunted ACh-mediated vasorelaxation in small mesenteric arteries from ANG. Reduced BH4/BH2 ratio was observed in small mesenteric arteries from ANG compared to NORM, which might be one of the mechanisms of NOS-mediated H2O2 production. Antioxidant enzyme capacity was also determined in small mesenteric arteries from ANG and NORM. Total superoxide dismutase (SOD) activity and protein expression of CuZn SOD and ecSOD were reduced in ANG compared to NORM, while Mn SOD expression was comparable between groups. Interestingly, both activity and expression of catalase were reduced in ANG compared to NORM, whereas GPx activity and expression were not changed. These results indicate that reduced catalase activity and expression may contribute to the augmentation of H2O2 in small mesenteric arteries from ANG, whereas reduced SOD does not greatly influence the H2O2 production in both basal and ACh-stimulated condition. In conclusion, the NOS pathway appears to be the primary endothelium-derived relaxing factor (EDRF) pathway in small mesenteric arteries from experimental animal models of hypertension. The increased dependence on the NOS pathway in ACh-induced vasorelaxation is mediated by both NOS-derived NO/cGMP signaling and NOS-mediated H2O2.