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A Southeast Asian expert consensus on the management of major depressive disorder with suicidal behavior in adults under 65 years of age. BMC Psychiatry 2022; 22:489. [PMID: 35864465 PMCID: PMC9306096 DOI: 10.1186/s12888-022-04140-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 07/06/2022] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND The high prevalence of suicidal behavior among individuals with major depressive disorder (MDD) in Southeast Asia (SEA) underscores the need for optimized management to address depressive symptoms, reduce suicide risk and prevent suicide in these individuals. Given the lack of clear guideline recommendations for assessing and managing these patients, regional consensus-based recommendations which take into account diverse local contexts across SEA may provide useful guidance for clinical practice. METHODS A narrative literature review and pre-meeting survey were conducted prior to the consensus meeting of an SEA expert panel comprising 13 psychiatrists with clinical experience in managing patients with MDD with suicidal behavior. Utilizing the RAND/UCLA Appropriateness Method, the expert panel developed consensus-based recommendations on the assessment and treatment of adult patients with MDD with suicidal behavior under 65 years. RESULTS Screening of adult patients under 65 years with MDD for suicide risk using both a validated assessment tool and clinical interview is recommended. An improved suicide risk stratification - incorporating both severity and temporality, or using a prevention-focused risk formulation - should be considered. For a patient with an MDD episode with low risk of suicide, use of antidepressant monotherapy, and psychotherapy in combination with pharmacological treatment are both recommended approaches. For a patient with an MDD episode with high risk of suicide, or imminent risk of suicide requiring rapid clinical response, or for a patient who had received adequate AD but still reported suicidal behavior, recommended treatment strategies include antidepressant augmentation, combination use of psychotherapy or electroconvulsive therapy with pharmacological treatment, and inpatient care. Suicide-specific psychosocial interventions are important for suicide prevention and should also be part of the management of patients with MDD with suicidal behavior. CONCLUSIONS There are still unmet needs in the assessment of suicide risk and availability of treatment options that can deliver rapid response in patients with MDD with suicidal behavior. These consensus recommendations on the management of adult patients with MDD with suicidal behavior under 65 years may serve as a useful guidance in diverse clinical practices across the SEA region. Clinical judgment based on careful consideration of individual circumstances of each patient remains key to determining the most appropriate treatment option.
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Contrary response of porcine articular cartilage below and over 1000 s -1. Clin Biomech (Bristol, Avon) 2021; 90:105506. [PMID: 34610506 DOI: 10.1016/j.clinbiomech.2021.105506] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 08/31/2021] [Accepted: 09/27/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Knee joints experience excessive loads quite frequently during sports activities, and these shocks could accelerate progressive degeneration in articular cartilage. METHODS Quasi-static and dynamic response of porcine knee articular cartilages were investigated in this research. Split Hopkinson Pressure Bars (SHPB) were utilized to examine the articular cartilage properties at strain rates between 0.01-2000 s-1. FINDINGS The results showed that strain rate is an important factor for articular cartilages, distinctively divided into above and below 1000 s-1. The articular cartilages exhibit a strain hardening phenomenon when shock loaded at strain rates under 1000 s-1. When loaded at strain rates over 1000 s-1, their ultimate strength and elastic modulus decreased with increasing strain rates. INTERPRETATION The biphasic structure of the cartilage explained the change of modulus. At the lower strain rates, fibers realigned and solidified the structure, while at higher strain rates, there is not enough time for the tissue fluid to move inside the cartilage, leading to a reduction in the deformability of the specimen and raising of Young's modulus. The results can be utilized to provide some useful data for biomaterial and computational works in the future.
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Study into the spread of heat from thermo-optic silicon photonic elements. OPTICS EXPRESS 2021; 29:36461-36468. [PMID: 34809057 DOI: 10.1364/oe.426748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/29/2021] [Indexed: 06/13/2023]
Abstract
Phase modulators based upon the thermo-optic effect are used widely in silicon photonics for low speed applications such as switching and tuning. The dissipation of the heat produced to drive the device to the surrounding silicon is a concern as it can dictate how compact and tightly packed components can be without concerns over thermal crosstalk. In this paper we study through modelling and experiment, on various silicon on insulator photonic platforms, how close waveguides can be placed together without significant thermal crosstalk from adjacent devices.
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Impact of a community-based medication delivery program for antihypertensive medications on adherence and blood pressure reduction. Eur Heart J 2021. [DOI: 10.1093/eurheartj/ehab724.3119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Elevated blood pressure (BP) is the leading risk of death globally, and its burden continues to rise, disproportionately so in low- and middle-income countries. Non-adherence to antihypertensive medications is a major cause of uncontrolled hypertension, leading to cardiovascular morbidity and mortality. Ensuring consistent medication access and possession is crucial in addressing non-adherence. Community-based medication delivery is a strategy that can lead to improvement in medication possession, medication adherence, and subsequently BP reduction.
Purpose
Our program in western Kenya piloted a community medication delivery program for hypertensive patients, aiming to remove structural barriers to medication possession and ensuring consistent access to antihypertensive medications. Here, we reviewed secondary clinical data to evaluate the impact of this program on BP reduction and medication adherence.
Methods
We conducted a retrospective analysis using clinical records of hypertensive patients who participated in the medication delivery program. Between September 2019 and March 2020, patients who received care from our community-based chronic disease management program also received anti-hypertensive medications delivered to them at their doorstep. We compared differences in self-reported medication adherence and BP reduction between patients who got medication deliveries versus those who did not. Mixed effect models, controlling for baseline measurements, age, gender, and health insurance status were used to analyze outcomes of interest.
Results
A total of 124 patient records (80.6% female) were reviewed. Baseline systolic blood pressure (SBP) was 155.7 mmHg and baseline self-reported adherence per the Voils DOSE-Nonadherence measure was 2.7, with 1 being perfect adherence and 5 representing poor adherence. 48.4% of patients received at least 1 successful medication delivery. Patients who did not receive any medication deliveries had an SBP increase of 1.5 mmHg relative to baseline, whereas patients who received 1 medication delivery had an SBP reduction of 8 mmHg and patients who received 2 or more medication deliveries had an SBP reduction of 15.2 mmHg (Figure 1). Similarly, change in self-reported medication adherence was poorer in patients who received no medication deliveries (+0.1) versus those who received one medication delivery (−0.5) or 2 or more deliveries (−0.7). Mixed-effect model estimates demonstrated that relative to patients who did not receive any medication deliveries, mean SBP reduction was significantly greater among individuals who did receive medication deliveries (Table 1).
Conclusions
A community medication delivery program in western Kenya led to improved medication adherence and systolic blood pressure reduction. This is a promising strategy to improve hypertension outcomes for patients with uncontrolled hypertension by removing structural barriers to medication possession.
Funding Acknowledgement
Type of funding sources: Public Institution(s). Main funding source(s): Purdue University Gloria Franke Pharmacy Practice Advancement Grant Change in blood pressure and adherenceMixed-effect model estimates
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Integration of low loss vertical slot waveguides on SOI photonic platforms for high efficiency carrier accumulation modulators. OPTICS EXPRESS 2020; 28:23143-23153. [PMID: 32752315 DOI: 10.1364/oe.397044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Silicon accumulation type modulators offer prospects of high power efficiency, large bandwidth and high voltage phase linearity making them promising candidates for a number of advanced electro-optic applications. A significant challenge in the realisation of such a modulator is the fabrication of the passive waveguide structure which requires a thin dielectric layer to be positioned within the waveguide, i.e. slotted waveguides. Simultaneously, the fabricated slotted waveguide should be integrated with conventional rib waveguides with negligible optical transition losses. Here, successful integration of polysilicon and silicon slot waveguides enabling a low propagation loss 0.4-1.2 dB/mm together with an ultra-small optical mode conversion loss 0.04 dB between rib and slot waveguides is demonstrated. These fabricated slot waveguide with dielectric thermal SiO2 layer thicknesses around 6 nm, 8 nm and 10 nm have been characterized under transmission electron microscopy allowing for strong carrier accumulation effects for MOS-capacitor electro-optic modulators.
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Nonconservative Coupling in a Passive Silicon Microring Resonator. PHYSICAL REVIEW LETTERS 2020; 124:013606. [PMID: 31976699 DOI: 10.1103/physrevlett.124.013606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Indexed: 06/10/2023]
Abstract
The authors report on nonconservative coupling in a passive silicon microring between its clockwise and counterclockwise resonance modes. The coupling coefficient is adjustable using a thermo-optic phase shifter. The resulting resonance of the supermodes due to nonconservative coupling is predicted in theory and demonstrated in experiments. This Letter paves the way for fundamental studies of on-chip lasers and quantum photonics, and their potential applications.
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Ultra-sharp asymmetric Fano-like resonance spectrum on Si photonic platform. OPTICS EXPRESS 2019; 27:7365-7372. [PMID: 30876301 DOI: 10.1364/oe.27.007365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 02/09/2019] [Indexed: 06/09/2023]
Abstract
In this paper, we report the generation of an ultra-sharp asymmetric resonance spectrum through Fano-like interference. This generation is accomplished by weakly coupling a high-quality factor (Q factor) Fabry-Pérot (FP) cavity and a low-Q factor FP cavity through evanescent waves. The high-Q FP cavity is formed by Sagnac loop mirrors, whilst the low-Q one is built by partially transmitting Sagnac loop reflectors. The working principle has been analytically established and numerically modelled by using temporal coupled-mode-theory (CMT), and verified using a prototype device fabricated on the 340 nm silicon-on-insulator (SOI) platform, patterned by deep ultraviolet (DUV) lithography. Pronounced asymmetric resonances with slopes up to 0.77 dB/pm have been successfully measured, which, to the best of our knowledge, is higher than the results reported in state-of-the-art devices in on-chip integrated Si photonic studies. The established theoretical analysis method can provide excellent design guidelines for devices with Fano-like resonances. The design principle can be applied to ultra-sensitive sensing, ultra-high extinction ratio switching, and more applications.
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Silicon-on-insulator free-carrier injection modulators for the mid-infrared. OPTICS LETTERS 2019; 44:915-918. [PMID: 30768019 DOI: 10.1364/ol.44.000915] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 12/01/2018] [Indexed: 06/09/2023]
Abstract
Experimental demonstrations of silicon-on-insulator waveguide-based free-carrier effect modulators operating at 3.8 μm are presented. PIN diodes are used to inject carriers into the waveguides, and are configured to (a) use free-carrier electroabsorption to create a variable optical attenuator with 34 dB modulation depth and (b) use free-carrier electrorefraction with the PIN diodes acting as phase shifters in a Mach-Zehnder interferometer, achieving a VπLπ of 0.052 V·mm and a DC modulation depth of 22 dB. Modulation is demonstrated at data rates up to 125 Mbit/s.
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Dominance of Tensor Correlations in High-Momentum Nucleon Pairs Studied by (p,pd) Reaction. PHYSICAL REVIEW LETTERS 2018; 121:242501. [PMID: 30608744 DOI: 10.1103/physrevlett.121.242501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Indexed: 06/09/2023]
Abstract
The isospin character of p-n pairs at large relative momentum has been observed for the first time in the ^{16}O ground state. A strong population of the J,T=1,0 state and a very weak population of the J,T=0,1 state were observed in the neutron pickup domain of ^{16}O(p,pd) at 392 MeV. This strong isospin dependence at large momentum transfer is not reproduced by the distorted-wave impulse approximation calculations with known spectroscopic amplitudes. The results indicate the presence of high-momentum protons and neutrons induced by the tensor interactions in the ground state of ^{16}O.
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Evidence for prevalent Z = 6 magic number in neutron-rich carbon isotopes. Nat Commun 2018; 9:1594. [PMID: 29686394 PMCID: PMC5913314 DOI: 10.1038/s41467-018-04024-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Accepted: 03/28/2018] [Indexed: 11/08/2022] Open
Abstract
The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called magic numbers of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped in explaining the magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number six in 13-20C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on 14,15C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics.
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Role of supportive maintenance therapy on implant survival: a university‐based 17 years retrospective analysis. Int J Dent Hyg 2015; 14:267-271. [DOI: 10.1111/idh.12188] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2015] [Indexed: 11/27/2022]
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Change in smoking status during two consecutive pregnancies: a population-based cohort study. BJOG 2014; 121:1611-20. [DOI: 10.1111/1471-0528.12769] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/24/2014] [Indexed: 10/25/2022]
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Abstract
The declining number of physician scientists is an alarming issue. A systematic review of all existing programs described in the literature was performed, so as to highlight which programs may serve as the best models for the training of successful physician scientists. Multiple databases were searched, and 1,294 articles related to physician scientist training were identified. Preference was given to studies that looked at number of confirmed publications and/or research grants as primary outcomes. Thirteen programs were identified in nine studies. Eighty-three percent of Medical Scientist Training Program (MSTP) graduates, 77% of Clinician Investigator Training Program (CI) graduates, and only 16% of Medical Fellows Program graduates entered a career in academics. Seventy-eight percent of MSTP graduates succeeded in obtaining National Institute of Health (NIH) grants, while only 15% of Mayo Clinic National Research Service Award-T32 graduates obtained NIH grants. MSTP physician scientists who graduated in 1990 had 13.5 ± 12.5 publications, while MSTP physician scientists who graduated in 1975 had 51.2 ± 38.3 publications. Additionally, graduates from the Mayo Clinic's MD-PhD Program, the CI Program, and the NSRA Program had 18.2 ± 20.1, 26.5 ± 24.5, and 17.9 ± 26.3 publications, respectively. MSTP is a successful model for the training of physician scientists in the United States, but training at the postgraduate level also shows promising outcomes. An increase in the number of positions available for training at the postgraduate level should be considered.
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The contribution of international medical students to Taiwanese medical school classes. MEDICAL TEACHER 2012; 35:78-79. [PMID: 22992023 DOI: 10.3109/0142159x.2012.716560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
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Configuration of microbially synthesized Pd-Au nanoparticles studied by STEM-based techniques. NANOTECHNOLOGY 2012; 23:055701. [PMID: 22236722 DOI: 10.1088/0957-4484/23/5/055701] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Bimetallic Pd-Au particles synthesized using Desulfovibrio desulfuricans bacteria are characterized using scanning transmission electron microscopy (STEM) with a high-angle annular dark field (HAADF) detector combined with energy dispersive x-ray (EDX) silicon drift detector (SDD) elemental mapping and plasmon electron energy-loss spectroscopy (EELS). When combined with EDX, theoretical considerations or EELS, the atomic-number contrast (Z-contrast) provided by HAADF-STEM is effective in characterizing the compositional configuration of the bimetallic nanoparticles. Homogeneous mixing and complex segregations have been found for different particles in this work. The EELS study has also found different behaviours corresponding to surface plasmon resonances in different regions of a single particle due to its heterogeneity and anisotropy. HAADF-STEM tomography has been performed to obtain three-dimensional (3D) visualization of the nanoparticles.
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Abstract
BACKGROUND Vietnam is one of the most populous countries in Southeast Asia, yet it displays an unsettling lack of doctors. AIMS Medical education is an important factor contributing to this issue, yet little is known about the system currently in place in Vietnam. METHODS Through an extensive literary search of medical schools' and Ministry of Health's data, we have examined the current medical education system in Vietnam. RESULTS At present, there are 12 medical universities, and the general curriculum at each university follows a national framework but tends to vary from university to university. Medical training lasts either 4 or 6 years, with competitive graduates attending residency programs following graduation. While examinations are required to graduate, the lack of a national licensing exam makes it difficult to ensure that a nation-wide standard of quality exists, both at the medical universities themselves as well as amongst the doctors graduating from them. CONCLUSIONS The development and institution of a national exam would introduce a standard of training throughout Vietnam's medical education system. Further, a substantial portion of a doctor's education is in subjects that are loosely related to medicine. When looking forward it will be important to evaluate whether or not these non-medical subjects detract from the quality of medical training.
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Further examination of presumptive Rhizobium trifolii mutants that nodulate Glycine max. Proc Natl Acad Sci U S A 2010; 76:3942-6. [PMID: 16592695 PMCID: PMC383952 DOI: 10.1073/pnas.76.8.3942] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two recent reports described the isolation of derivatives of a Rhizobium trifolii strain that had gained the ability to nodulate Glycine max and Vigna radiata and that had demonstrated altered patterns of carbon source utilization, free-living nitrogen fixation, and hydrogen uptake. More extensive characterization of these strains now supports the conclusion that these strains are R. japonicum and are not derived from the putative parent R. trifolii.
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Drink a little; take a few drugs: do nurses have knowledge to identify and manage in-patients at risk of drugs and alcohol? Drug Alcohol Rev 2009; 26:545-52. [PMID: 17701518 DOI: 10.1080/09595230701499167] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION AND AIMS The widespread use of alcohol and other drugs poses particular problems during hospitalisation. Although nurses have been identified as an appropriate group to screen patients and provide acute and ongoing management to people with drug and alcohol-related problems, rates of screening are low. The aims of this study were to identify current practices for screening by nurses working in medical and surgical wards, determine their knowledge relating to problems associated with substance use and identify their self-reported skills in managing patients with drug- and alcohol-related problems. DESIGN AND METHODS A chart audit of medical records was completed and a survey was distributed to nurses working in the study wards. RESULTS Screening for alcohol and drug use was documented on only 22/79 medical records, and detailed information about quantity and duration of use was recorded in only nine. Overall, the nurses reported that they had little knowledge about substance use problems, and felt that they lacked skills to care adequately for these patients. DISCUSSION AND CONCLUSIONS The results of this study suggest a need for a comprehensive training and education to ensure that nurses are familiar with policies and protocols for management of patients and to assist nurses to provide evidence-based care and make appropriate referrals to specialist services.
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Patient-centered design for a personal health record system. AMIA ... ANNUAL SYMPOSIUM PROCEEDINGS. AMIA SYMPOSIUM 2005; 2005:1140. [PMID: 16779426 PMCID: PMC1560647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Our objective for this project was to design a user interface (UI) for a patient-centered personal health record system that models how patients view their health information. We assessed user needs, examined how patients label and categorize health information, and evaluated two user interfaces that we designed for the Patient-Centered Health Record (PcHR) system. Our design process focused on discovering useful content and ensuring that the UI was intuitive, easy to use, and helpful for users.
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Abstract
The objective of this study was to determine whether connexin 32-type gap junctions contribute to the "contact effect" in follicular thyrocytes and whether the response is influenced by radiation quality. Our previous studies demonstrated that early-passage follicular cultures of Fischer rat thyroid cells express functional connexin 32 gap junctions, with later-passage cultures expressing a truncated nonfunctional form of the protein. This model allowed us to assess the role of connexin 32 in radiation responsiveness without relying solely on chemical manipulation of gap junctions. The survival curves generated after gamma irradiation revealed that early-passage follicular cultures had significantly lower values of alpha (0.04 Gy(-1)) than later-passage cultures (0.11 Gy(-1)) (P < 0.0001, n = 12). As an additional way to determine whether connexin 32 was contributing to the difference in survival, cultures were treated with heptanol, resulting in higher alpha values, with early-passage cultures (0.10 Gy(-1)) nearly equivalent to untreated late-passage cultures (0.11 Gy(-1)) (P > 0.1, n = 9). This strongly suggests that the presence of functional connexin 32-type gap junctions was contributing to radiation resistance in gamma-irradiated thyroid follicles. Survival curves from proton-irradiated cultures had alpha values that were not significantly different whether cells expressed functional connexin 32 (0.10 Gy(-1)), did not express connexin 32 (0.09 Gy(-1)), or were down-regulated (early-passage plus heptanol, 0.09 Gy(-1); late-passage plus heptanol, 0.12 Gy(-1)) (P > 0.1, n = 19). Thus, for proton irradiation, the presence of connexin 32-type gap junctional channels did not influence their radiosensitivity. Collectively, the data support the following conclusions. (1) The lower alpha values from the gamma-ray survival curves of the early-passage cultures suggest greater repair efficiency and/or enhanced resistance to radiation-induced damage, coincident with the expression of connexin 32-type gap junctions. (2) The increased sensitivity of FRTL-5 cells to proton irradiation was independent of their ability to communicate through connexin 32 gap junctions. (3) The fact that the beta components of the survival curves from both gamma rays and proton beams were similar (average 0.022 +/- 0.008 Gy(-2), P > 0.1, n = 39) suggests that at higher doses the loss of viability occurs at a relatively constant rate and is independent of radiation quality and the presence of functional gap junctions.
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A spontaneously arising mutation in connexin32 with repeated passage of FRTL-5 cells coincides with increased growth rate and reduced thyroxine release. J Mol Endocrinol 2001; 27:145-63. [PMID: 11564600 DOI: 10.1677/jme.0.0270145] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this study we examine changes in the cellular properties of FRTL-5 cells as a function of passage number, with particular emphasis on gap junction expression, karyotype, morphology, growth rate and thyroxine (T(4)) release. Early passage FRTL-5 follicular cells transfer dye through gap junctions from injected cell(s) to third-order neighboring cells and beyond within their respective follicles and have immuno-detectable connexin32 (Cx32) type gap junctional plaques in their lateral contacting plasma membranes. By contrast, FRTL-5 cells established as monolayers, or as follicles from cultures passed more than 15 times, did not transfer microinjected Lucifer Yellow dye to contiguous neighboring cells and did not express any immuno-detectable rat thyroid specific connexins (Cx43, Cx32 or Cx26). Western blots confirmed that total, membrane and cytosolic Cx32 protein was present only in early pass follicular cultures. To better understand the passage-dependent loss of Cx32 expression, RT-PCR primers were made to the most unique sequences of the rat Cx32 molecule, the cytoplasmic and carboxyl-terminal regions. These primers were used to screen FRTL-5 RNA from cultures of various passage numbers. The results revealed that later passage cultures had a single base deletion in the middle of the Cx32 cytoplasmic loop region at nucleotide position 378. This base deletion was in the middle position of the codon for amino acid 116, which is normally a CAC (histidine) but read with the frame shift was a CCC (proline). The four amino acids that followed this deletion were also altered with the fourth one becoming UAA, the ochre translation stop codon. This premature stopping of translation resulted in a truncation of 60% of the protein, which included the remaining cytoplasmic loop, third and fourth transmembrane regions and the carboxyl-terminus. The later passage cultures did not produce a carboxyl-terminal RT-PCR product, indicating that the mRNA was also truncated. These regions of the Cx32 molecule contain the sequences and epitopes to which probes and antibodies are directed, and as such alterations of these regions with repeated passage explains reports by others that FRTL-5 cells do not express Cx32, and implies that cultures used for these assessments were passed more than 15 times. To determine if genetic or epigenetic abnormalities existed in FRTL-5 cells we performed chromosome spreads from various passage cultures. FRTL-5 cells have been reported to be diploid and more recently non-diploid; however, we found them to be fully tetraploid. This tetraploidy appears to be unstable in that later passes are tetraploid plus two or three extra chromosomes. There were no obvious translocations, breaks or large-scale interstitial deletions of any chromosomes in the FRTL-5 cultures tested. As FRTL-5 cells were repeatedly passed their morphology changed. Monolayer areas spread from beneath the follicles, and the follicles became flattened in appearance. These physical changes were coincident with dramatically increased growth rates. Early cultures (passed 3-12 times) divided on average every 49+/-1 h, whereas later passes (passes 20-25) divided every 28+/-3 h. To correlate these changes with a measure of thyroid function we assayed T(4) output. Early passage follicular cultures incubated for 6 h with sodium iodide, released on average 5.27+/- 0.33 ng/ml of T(4)/100 follicles. Later passes, or early passes treated with heptanol to down-regulate Cx32, released an average of 3.84+/-0.50 ng/ml of T(4)/100 follicles. There was a 27% difference in T(4) release between early follicular cultures, that were coupled by Cx32, and late or down-regulated early follicular cultures, that were uncoupled (P<0.0001). Collectively, the physical changes documented in this study were coincident with the loss of functional Cx32. This implies a relationship between the loss of intercellular communication and changes in morphogenic appearance, growth rate and reduced thyroid function and supports the previously postulated, tumor-suppressor role for Cx32. FRTL-5 cultures from low passage numbers are an excellent model of primary thyroid cells. However, many reports in the literature ascribe features to FRTL-5 cells that are mutually inconsistent. These differences may be resolved in the future by addressing the passage number and the conditional differences of the cultures being studied.
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Response of thyroid follicular cells to gamma irradiation compared to proton irradiation. I. Initial characterization of DNA damage, micronucleus formation, apoptosis, cell survival, and cell cycle phase redistribution. Radiat Res 2001; 155:32-42. [PMID: 11121213 DOI: 10.1667/0033-7587(2001)155[0032:rotfct]2.0.co;2] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The RBE of protons has been assumed to be equivalent to that of photons. The objective of this study was to determine whether radiation-induced DNA and chromosome damage, apoptosis, cell killing and cell cycling in organized epithelial cells was influenced by radiation quality. Thyroid-stimulating hormone-dependent Fischer rat thyroid cells, established as follicles, were exposed to gamma rays or proton beams delivered acutely over a range of physical doses. Gamma-irradiated cells were able to repair DNA damage relatively rapidly so that by 1 h postirradiation they had approximately 20% fewer exposed 3' ends than their counterparts that had been irradiated with proton beams. The persistence of free ends of DNA in the samples irradiated with the proton beam implies that either more initial breaks or a quantitatively different type of damage had occurred. These results were further supported by an increased frequency of chromosomal damage as measured by the presence of micronuclei. Proton-beam irradiation induced micronuclei at a rate of 2.4% per gray, which at 12 Gy translated to 40% more micronuclei than in comparable gamma-irradiated cultures. The higher rate of micronucleus formation and the presence of larger micronuclei in proton-irradiated cells was further evidence that a qualitatively more severe class of damage had been induced than was induced by gamma rays. Differences in the type of damage produced were detected in the apoptosis assay, wherein a significant lag in the induction of apoptosis occurred after gamma irradiation that did not occur with protons. The more immediate expression of apoptotic cells in the cultures irradiated with the proton beam suggests that the damage inflicted was more severe. Alternatively, the cell cycle checkpoint mechanisms required for recovery from such damage might not have been invoked. Differences based on radiation quality were also evident in the alpha components of cell survival curves (0.05 Gy(-1) for gamma rays, 0.12 Gy(-1) for protons), which suggests that the higher level of survival of gamma-irradiated cells could be attributed to the persistence of nonlethally irradiated thyrocytes and/or the capacity to repair damage more effectively than cells exposed to equal physical doses of protons. The final assessment in this study was radiation-induced cell cycle phase redistribution. Gamma rays and protons produced a similar dose-dependent redistribution toward a predominantly G(2)-phase population. From our cumulative results, it seems likely that a majority of the proton-irradiated cells would not continue to divide. In conclusion, these findings suggest that there are quantitative and qualitative differences in the biological effects of proton beams and gamma rays. These differences could be due to structured energy deposition from the tracks of primary protons and the associated high-LET secondary particles produced in the targets. The results suggest that a simple dose-equivalent approach to dosimetry may be inadequate to compare the biological responses of cells to photons and protons.
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Candidacidal activity prompted by N-terminus histatin-like domain of human salivary mucin (MUC7)1. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1431:107-19. [PMID: 10209284 DOI: 10.1016/s0167-4838(99)00034-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Histidine-rich peptides (histatins, Hsn) in saliva are thought to provide a non-immune defense against Candida albicans. Sequence homology search of the human salivary mucin, MUC7, against histatins revealed a domain at the N-terminus (R3-Q17) having 53% identity to Hsn-5. To determine its candidacidal activity, this 15 residue basic histidine-rich domain of MUC7 (I) was prepared by solid-phase Fmoc chemistry. Various N- and C-terminal protected derivatives of I were also synthesized to correlate the effect of peptide overall charge in exhibiting cidal potency. Candidacidal activity measurement of I and its variants showed considerable ED50 values (effective dosage required to kill 50% of candida cells), albeit greater than Hsn-5 (ED50 approximately 4-6 microM). Of the various analogs tested, N-terminal free acid (I, ED50 approximately 40 microM) and amide (V, ED50 approximately 16 microM) exhibited appreciable candidacidal activities suggesting the possible role of peptide net charge in cidal action. Blocking of N-terminus with a bulky octanoyl group showed only marginal effect on the cidal activity of I or V, indicating that hydrophobicity of these synthetic constructs may not be important for exerting such activities. Membrane-induced conformational transition from random coil to helical structures of all the test peptides implied their tendency to adapt order structures at the lipid-membrane interface similar to that of Hsn-5. However, comparison of propensity for helical structure formation vs. ED50 indicated that cidal potency of MUC7 Hsn-like peptides depends largely on electrostatic interactions irrespective of secondary structural elements. Delineation of solution structure of the most active peptide (V) by 2D-NMR revealed essentially a non-structured conformation in aqueous medium, which further supported the fact that the peptide helical structure may not be a prerequisite for posing candidacidal activity. The formation of smaller truncated peptides and/or Hsn-like fragments on proteolytic degradation of intact MUC7 in the presence of oral flora provided indirect evidence that mucin could serve as a backup candidacidal agent to salivary Hsn.
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Abstract
A subinfective dose of Staphylococcus aureus (6 X 10(6)) does not produce wound infection in the rat model. Reducing the dosage (concentration) of epinephrine results in decreased numbers of viable bacteria in tissue and a lower incidence of wound infection in this model.
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