1
|
A Novel Home-Based Medication Management Program and Its Influence on Hospitalization Rates among Home Health Care Recipients. J Am Med Dir Assoc 2024; 25:155-157.e1. [PMID: 37989498 DOI: 10.1016/j.jamda.2023.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 10/11/2023] [Accepted: 10/11/2023] [Indexed: 11/23/2023]
Abstract
Patients do not take their medicine as prescribed 50% of the time, and of medication-related hospital admissions in the United States, 33% to 69% are due to poor medication adherence, at a cost of approximately $100 billion a year. Continue CareRx (CCRx) is a novel home-based medication management program that includes adherence packaging alongside medication reconciliation, review, and education by clinicians. We hypothesized that home health patients receiving the CCRx service may have a lower hospitalization rate than control home health patients. Between May 1, 2021, and March 31, 2023, 113 home health patients whose insurance covered the program were enrolled in CCRx. Home health patients not eligible for the program due to a noncovered pharmacy insurance benefit made up the control group (n = 21,304), which was matched with the CCRx group on age range (45-99 years old) and gender (67% women). Hospitalization rate was calculated in both groups and compared using generalized estimating equations analysis. The control group had a total of 7015 hospitalizations during the study period during 2,128,738 total managed days, whereas the CCRx group had 21 hospitalizations during 23,622 total managed days. These translated into rates of 1203 hospitalizations per 1000 per year for the control group, and 324 hospitalizations per 1000 per year for the CCRx group. The results showed that there was a significant main effect of group in predicting individual annual hospitalization rate (Wald χ2 = 56.415, P < .01). Specifically, being in the control group was associated with a 43.42-fold increase in the likelihood of a higher hospitalization rate (95% Wald CI for odds ratios: 7.24-230.44). Home health recipients enrolled in CCRx experienced a 73.1% lower hospitalization rate than controls. Making the program more widely available to patients receiving home health care may present a significant opportunity to reduce hospitalizations in this group.
Collapse
|
2
|
Variation in Value-Based Outcome Measures Among Assisted Living Communities Served by a Home-Based Primary Care Practice During COVID-19. HOME HEALTH CARE MANAGEMENT AND PRACTICE 2021. [DOI: 10.1177/1084822320963094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We aimed to determine the hospitalization rate and average days spent at home in a population of assisted living (AL) residents served by a home-based primary care (HBPC) practice during the COVID-19 pandemic. We provided on-site HBPC to 1,699 AL residents and calculated hospitalization rate and days spent at home. The AL population had a mean age of 84 ± 10 years and 73% were female. The mean hospitalization rate was 449 admissions per 1,000 per year, and there was wide variation among AL communities. AL residents spent a mean of 358 days at home per year, and the average days spent at home varied during the COVID-19 pandemic. Use of these measures may help AL articulate its value proposition by enabling seniors with complex health needs to live in community settings for as many days as possible.
Collapse
|
3
|
An Outbreak Preparedness and Mitigation Approach in Home Health and Personal Home Care During the COVID-19 Pandemic. HOME HEALTH CARE MANAGEMENT AND PRACTICE 2020; 32:229-233. [PMID: 38602996 PMCID: PMC7270573 DOI: 10.1177/1084822320933567] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The acute respiratory disease COVID-19, caused by the novel Coronavirus SARS-CoV-2, is a worldwide pandemic affecting millions of people. The methodology that organizations who provide home health and personal home care services are using to respond to this pandemic has not yet been characterized. In this report, we describe our approach to comprehensive outbreak suppression and report an initial case series of COVID-19 positive patients receiving home-based services. We implemented enhanced infection control procedures across our affiliates, and we communicated these protocols to our offices using multi-faceted methods. Using custom built software applications enabling us to track patient and employee cases and exposures, we leveraged current public health recommendations to identify cases and to suppress transmission. In the 100-day period between January 20, 2020 and April 30, 2020, our affiliates provided services to 67 COVID-19 positive patients (<0.3% of census). Twenty patients were referred to home health post hospitalization for COVID-19 related illness, whereas 47 were found to have COVID-19 while living in community settings. Of those who were found to have COVID-19 in the community, 17 (39%) required subsequent hospitalization. Hospitalized patients had an average age of 74.5 ± 18, and 53% were male. There were 13 deaths (76%) among those hospitalized from the community with COVID-19 related illness. A highly coordinated and frequently communicated approach to infection control, case identification and employee screening can be performed by home health and personal home care organizations. Studies that further assess risks and predictors of illness severity in home-based COVID-19 patients are needed.
Collapse
|
4
|
Hydroxychloroquine Sulfate Prescribing Trends and Pharmacist-Led Outbreak Preparedness in Long-Term Care Pharmacy during Coronavirus Disease 2019. J Am Med Dir Assoc 2020; 21:1000-1001. [PMID: 32674811 PMCID: PMC7284252 DOI: 10.1016/j.jamda.2020.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 06/08/2020] [Accepted: 06/08/2020] [Indexed: 12/03/2022]
|
5
|
Abstract
In 2015, the Centers for Medicare & Medicaid Services (CMS) implemented a new benefit called chronic care management (CCM). A recent CMS-commissioned study of the program showed that CCM is effective in increasing advance care planning and decreasing overall costs. Despite positive effects on care planning, utilization, and cost, the CCM program remains underutilized. The authors sought to develop a platform to enable scale of the CCM program, and to report outcomes associated with its use. A technology and integrated clinical staff platform was built to enable a scalable, evidence-based implementation of the Medicare CCM program. The model created care management data elements that were used to flag clinical and utilization risks such as falls, mortality, hospitalization and polypharmacy. In 2018, CCM support was provided for 26,500 patients. Logistic regression analyses were used to identify risk factors associated with hospitalization. The cohort experienced 2679 hospitalizations (184 admissions per 1000 patient months per year). Among patients residing in non-nursing home settings, a higher Gagne mortality risk was associated with a 32 times greater chance of being hospitalized. Other positive predictors of hospitalization included being a nursing home resident and being ambulatory without assistance. Negative predictors of hospitalization included being flagged as having a high hospitalization risk, and scoring in the low-risk category for falls or polypharmacy. This CCM model is a scalable method of supporting care management for people with multiple chronic conditions, and can help identify risk factors for hospitalization.
Collapse
|
6
|
Abstract
Prolongation or reestablishment of stem cell homing through the expression of SDF-1 in the myocardium has been shown to lead to homing of endothelial progenitor cells to the infarct zone with a subsequent increase in vascular density and cardiac function. While the increase in vascular density is important, there could clearly be other mechanisms involved. In a recent study we demonstrated that the infusion of mesenchymal stem cells (MSC) and MSC that were engineered to overexpress SDF-1 led to significant decreases in cardiac myocyte apoptosis and increases in vascular density and cardiac function compared to control. In that study there was no evidence of cardiac regeneration from either endogenous stem cells or the infused mesenchymal stem cells. In this study we performed further detailed immunohistochemistry on these tissues and demonstrate that the overexpression of SDF-1 in the newly infracted myocardium led to recruitment of small cardiac myosin-expressing cells that had proliferated within 2 weeks of acute MI. These cells did not differentiate into mature cardiac myocytes, at least by 5 weeks after acute MI. However, based on optical mapping studies, these cells appear capable of depolarizing. We observed greater optical action potential amplitude in the infarct border in those animals that received SDF-1 overexpressing MSC than observed in noninfarcted animals and those that received control MSC. Further immunohistochemistry revealed that these proliferated cardiac myosin-positive cells did not express connexin 43, but did express connexin 45. In summary, our study suggests that the prolongation of SDF-1 expression at the time of acute MI leads to the recruitment of endogenous cardiac myosin stem cells that may represent cardiac stem cells. These cells are capable of depolarizing and thus may contribute to increased contractile function even in the absence of maturation into a mature cardiac myocyte.
Collapse
|
7
|
Gamma Radiation from Inelastic Scattering of 14-Mev Neutrons by the Common Earth Elements. NUCL SCI ENG 2017. [DOI: 10.13182/nse60-a25797] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
8
|
|
9
|
|
10
|
Home Is Where the Heart of the ACO Is. J Am Med Dir Assoc 2013; 14:527. [DOI: 10.1016/j.jamda.2013.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Accepted: 04/03/2013] [Indexed: 10/26/2022]
|
11
|
Hospital Care of Assisted Living Residents by an Assisted Living Based Primary Care Team. HOME HEALTH CARE MANAGEMENT AND PRACTICE 2013. [DOI: 10.1177/1084822312471340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The objective of this article is to characterize inpatient-related outcomes and measures of efficiency for hospitalized assisted living residents managed by an assisted living-based primary care (ALPC) team. Between 2010 and 2012, 1594 assisted living residents received ALPC. An ALPC team member served as hospital attending physician to 377 assisted living residents at three community hospitals. Several inpatient metrics were compared between the hospitalized ALPC cohort and those reported in the National Hospital Discharge Survey. Hospitalized assisted living residents who received inpatient hospital care by an ALPC team member had lower inpatient mortality, 30-day readmission rates, and shorter length of stay compared to published averages. The authors determined that an ALPC team who follows its patients in the hospital may achieve improved inpatient outcomes.
Collapse
|
12
|
|
13
|
Stem cell therapy enhances electrical viability in myocardial infarction. J Mol Cell Cardiol 2007; 42:304-14. [PMID: 17070540 DOI: 10.1016/j.yjmcc.2006.09.011] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2006] [Revised: 09/12/2006] [Accepted: 09/20/2006] [Indexed: 02/07/2023]
Abstract
Clinical studies suggest increased arrhythmia risk associated with cell therapy for myocardial infarction (MI); however, the underlying mechanisms are poorly understood. We hypothesize that the degree of electrical viability in the infarct and border zone associated with skeletal myoblast (SKMB) or mesenchymal stem cell (MSC) therapy will determine arrhythmia vulnerability in the whole heart. Within 24 h of LAD ligation in rats, 2 million intramyocardially injected SKMB (n=6), intravenously infused MSC (n=7), or saline (n=7) was administered. One month after MI, cardiac function was determined and novel optical mapping techniques were used to assess electrical viability and arrhythmia inducibility. Shortening fraction was greater in rats receiving SKMB (17.8%+/-5.3%, p=0.05) or MSC (17.6%+/-3.0%, p<0.01) compared to MI alone (10.1%+/-2.2%). Arrhythmia inducibility score was significantly greater in SKMB (2.8+/-0.2) compared to MI (1.4+/-0.5, p=0.05). Inducibility score for MSC (0.6+/-0.4) was significantly lower than SKMB (p=0.01) and tended to be lower than MI. Optical mapping revealed that MSC therapy preserved electrical viability and impulse propagation in the border zone, but SKMB did not. In addition, injected SKMBs were localized to discrete cell clusters where connexin expression was absent. In contrast, infused MSCs engrafted in a more homogeneous pattern and expressed connexin proteins. Even though both MSC and SKMB therapy improved cardiac function following MI in rat, SKMB therapy significantly increased arrhythmia inducibility while MSC therapy tended to lower inducibility. In addition, only MSC therapy was associated with enhanced electrical viability, diffuse engraftment, and connexin expression, which may explain the differences in arrhythmia inducibility.
Collapse
|
14
|
Mechanical and Electrical Effects of Cell-Based Gene Therapy for Ischemic Cardiomyopathy Are Independent. Hum Gene Ther 2006; 17:1144-51. [PMID: 17069537 DOI: 10.1089/hum.2006.17.1144] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Cell-based gene therapy to alter the myocardial tissue microenvironment has been shown to improve mechanical cardiac function, but little is known regarding its effects on arrhythmogenic risk. Clinical studies with skeletal myoblasts (SKMBs) have suggested a potential increase in arrhythmogenic risk. Therefore, we studied the functional mechanical and electrical effects of transient reestablishment of stem cell homing via transplantation of stromal-cell derived factor-1 (SDF-1)-expressing SKMBs. Eight weeks after anterior myocardial infarction, rats received in five divided doses into the periinfarct zone 1 million SKMBs transfected with AdSDF-1 (n=15) or AdGFP (n=8). Echocardiography was used to quantify changes in cardiac function, and optical mapping was used to determine the arrhythmogenic risk. Eight weeks after cell therapy, we observed a 54% (p=0.004) increase in shortening fraction in AdSDF-1:SKMB-treated rats, but only an 18.8% increase (p=not significant) with GFP:SKMB. SDF-1-treated hearts exhibited an increase in vascular density compared with control SKMBs (34.9+/-7.1 vs. 20.7+/-5.6 vessels/mm2; p<0.01). Optical mapping performed 8 weeks after cell therapy revealed that all animals that received SKMBs regardless of viral transfection had inducible ventricular tachycardia (VT) whereas only 50% of saline-treated animals had inducible VT (p<0.05). Transient reestablishment of stem cell homing via transplantation of modified SKMBs is sufficient to improve cardiac function. However, despite improved mechanical function, the risk of ventricular tachycardia increased. We propose that future studies on functional effects of cell-based gene therapies should address both mechanical and electrical consequences.
Collapse
|
15
|
Mechanical and Electrical Effects of Cell-Based Gene Therapy for Ischemic Cardiomyopathy Are Independent. Hum Gene Ther 2006. [DOI: 10.1089/hum.2006.17.ft-255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
16
|
Mitral Valve Surgery in the Adult Marfan Syndrome Patient. Ann Thorac Surg 2006; 81:843-8. [PMID: 16488682 DOI: 10.1016/j.athoracsur.2005.08.055] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 08/26/2005] [Accepted: 08/29/2005] [Indexed: 11/25/2022]
Abstract
BACKGROUND Because mitral valve dysfunction in adults with Marfan syndrome is poorly characterized, this study compares mitral valve pathophysiology and morphology with that of myxomatous mitral disease, documents types of mitral valve operations, and assesses long-term survival and durability of mitral valve surgery in Marfan patients. METHODS From May 1975 to June 2000, 27 adults with Marfan syndrome underwent mitral valve surgery. Their valve pathophysiology and morphology was compared with that of 119 patients with myxomatous mitral disease undergoing surgery from September 1995 to March 1999. Survival and repair durability were assessed at follow-up. RESULTS Compared with myxomatous disease patients, Marfan patients had less posterior leaflet prolapse (44% versus 70%, p = 0.01), more bileaflet (44% versus 28%, p = 0.09) and anterior leaflet prolapse (11% versus 3%, p = 0.07), and presented earlier for surgery (age 41 +/- 12 years versus 57 +/- 13, p < 0.0001). Marfan patients had longer and thinner leaflets. Mitral valve repair was performed less frequently in Marfan (16 of 27, 59%) than myxomatous disease patients (112 of 119, 94%). There were no hospital deaths; at 10 years, survival was 80% and freedom from reoperation 96%, with only 1 reoperation among the 16 repairs. CONCLUSIONS Mitral valve pathophysiology and morphology differ between Marfan and myxomatous mitral valve diseases. Valve repair in Marfan patients is durable and gives acceptable long-term results, even in adults who present with advanced mitral valve pathology. With increasing use of the modified David reimplantation operation and sparing of the aortic valve, mitral valve repair is a greater imperative, particularly since we have not had to reoperate on any Marfan patients with reimplantations.
Collapse
|
17
|
Abstract
Late myocardial infarction (MI) is associated with ventricular arrhythmias and sudden cardiac death. The exact mechanistic relationship between abnormal cellular electrophysiology, conduction abnormalities, and arrhythmogenesis associated with late MI is not completely understood. We report a novel, rapid dye superfusion technique to enable whole heart, high-resolution optical mapping of late MI. Optical mapping of action potentials was performed in normal rats and rats with anterior MI 7 days after left anterior descending artery ligation. Hearts from normal rats exhibited normal action potentials and impulse conduction. With the use of programmed stimulation to assess arrhythmia inducibility, 29% of hearts with late MI had inducible sustained ventricular tachycardia, compared with 0% in normal rats. A causal relationship between the site of infarction, abnormal action potential conduction (i.e., block and slow conduction), and arrhythmogenesis was observed. Optical mapping techniques can be used to measure high-resolution action potentials in a whole heart model of late MI. This experimental model reproduces many of the electrophysiological characteristics (i.e., conduction slowing, block, and ventricular tachycardia) associated with MI in patients. Importantly, the results of this study can enhance our ability to understand the interplay between cellular heterogeneity, conduction abnormalities, and arrhythmogenesis associated with MI.
Collapse
|
18
|
Does transplantation of skeletal myoblasts genetically modified to overexpress stromal-derived factor 1 restore normal conduction in chronic ischemic heart disease? Heart Rhythm 2005. [DOI: 10.1016/j.hrthm.2005.02.439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
19
|
Relation of calcium-phosphorus product to the severity of aortic stenosis in patients with normal renal function. Am J Cardiol 2004; 94:1196-8. [PMID: 15518622 DOI: 10.1016/j.amjcard.2004.07.095] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Revised: 07/15/2004] [Accepted: 07/15/2004] [Indexed: 11/23/2022]
Abstract
Calcium-phosphorus product (CaxP) has been associated with severity of aortic stenosis (AS) in dialysis patients, but it is unknown whether a relation exists in patients with normal renal function. One hundred seven patients with AS and normal serum creatinine were studied to determine whether there was an association between CaxP and AS severity, and it was found that CaxP was inversely related to AS severity, as measured by aortic valve area and transvalvular gradients.
Collapse
|
20
|
Biomechanical and echocardiographic characterization of flail mitral leaflet due to myxomatous disease: further evidence for early surgical intervention. Am Heart J 2004; 148:144-50. [PMID: 15215804 DOI: 10.1016/j.ahj.2004.01.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Flail mitral leaflet (FML) is a common complication of mitral valve prolapse, often leading to severe mitral regurgitation (MR) and left ventricular dysfunction. In the absence of timely surgical correction, survival is significantly impaired. Early recognition of FML and identification of risk factors is important because early intervention increases the chances of survival. METHODS We studied 123 patients undergoing mitral valve surgery for severe MR caused by myxomatous disease. Chart review, echocardiography, and tensile testing were performed. RESULTS Thirty-eight patients had FML, and 85 patients had non-flail mitral leaflet (non-FML). Patients with FML were younger (53.7 +/- 1.8 vs 59.3 +/- 1.4 years, P =.02), had more severe MR (3.89 +/- 0.04 vs 3.76 +/- 0.04, P =.02), were less likely to be in New York Heart Association class III or IV heart failure (5% vs 20%, P =.037), and were less likely to have bileaflet mitral valve prolapse (5% vs 38%, P <.001) than non-FML patients. Valve tissue from patients with FML had less stiff chordae (23.5 +/- 3.6 vs 59.1 +/- 11.7 Mpa, P =.006) that tended to have a lower failure stress (3.8 +/- 0.9 vs 9.6 +/- 2.2 Mpa, P =.07) and had more extensible leaflets (56.4% +/- 7.9% vs 42.9% +/- 2.7% strain, P =.04) compared with that of non-FML patients. CONCLUSIONS The development of FML may result from intrinsic tissue abnormalities and is associated with a distinct subset of the myxomatous population. Identification of such clinical characteristics in this population and knowledge of an implicit mechanical abnormality of valve tissue may further the argument for early surgical correction.
Collapse
|
21
|
1107-139 Calcium-phosphorus product is associated with severity of aortic stenosis in patients with normal renal function. J Am Coll Cardiol 2004. [DOI: 10.1016/s0735-1097(04)91828-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
22
|
Abstract
Mitral valve prolapse (MVP) is the most common cause of severe mitral regurgitation necessitating surgical correction. Unileaflet prolapse (ULP), usually involving the posterior leaflet, is more common than bileaflet prolapse (BLP), which is more difficult to repair. Little is known about clinical, echocardiographic, and biomechanical differences between ULP and BLP. In this study, biomechanical testing was performed on mitral valve leaflets and chordae obtained at operation for severe mitral regurgitation. Preoperative clinical characteristics and echocardiographic measurements were obtained on surgical patients (ULP = 88, BLP = 37). Men outnumbered women by a factor of 4:1 in ULP, and by 3:1 in BLP. Patients with BLP were younger (53.2 +/- 1.7 vs 59.5 +/- 1.1 years) than those with ULP, and this difference was greater in women (48.9 +/- 2.5 vs 62.9 +/- 2.2 years). BLP patients were less likely to be hypertensive, and more likely to undergo valve replacement rather than repair. Echocardiography showed that BLP leaflets were longer and thicker than ULP leaflets. The severity of mitral regurgitation was similar in both groups, although ULP patients had a much higher incidence of flail leaflets (45% vs 5% in BLP). Mechanical strength of chordae was greater in BLP than in ULP, although leaflet strength was similar. The increased chordal strength in BLP may be responsible for less flail. In patients with MVP and severe mitral regurgitation requiring surgery, ULP and BLP are distinct entities with substantial differences in the population affected, in echocardiographic manifestations including prevalence of flail, in chordal mechanics, and in the likelihood of surgical repair.
Collapse
|
23
|
DEVELOPING INDIRECT POTABLE REUSE TO INCREASE WATER SUPPLY, IMPROVE WATER QUALITY AND MANAGE WASTEWATER DISCHARGE IN ORANGE COUNTY CALIFORNIA. ACTA ACUST UNITED AC 2000. [DOI: 10.2175/193864700784546341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
24
|
Photosynthetic formation of the aspartate family of amino acids in isolated chloroplasts. PLANT PHYSIOLOGY 1980; 65:1166-72. [PMID: 16661353 PMCID: PMC440503 DOI: 10.1104/pp.65.6.1166] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The metabolism of (14)C-labeled aspartic acid, diaminopimelic acid, malic acid and threonine by isolated pea (Pisum sativum L.) chloroplasts was examined. Light enhanced the incorporation of [(14)C] aspartic acid into soluble homoserine, isoleucine, lysine, methionine and threonine and protein-bound aspartic acid plus asparagine, isoleucine, lysine, and threonine. Lysine (2 millimolar) inhibited its own formation as well as that of homoserine, isoleucine and threonine. Threonine (2 millimolar) inhibited its own synthesis and that of homoserine but had only a small effect on isoleucine and lysine formation. Lysine and threonine (2 millimolar each) in combination strongly inhibited their own synthesis as well as that of homoserine. Radioactive [1,7-(14)C]diaminopimelic acid was readily converted into [(14)C]threonine in the light and its labeling was reduced by exogenous isoleucine (2 millimolar) or a combination of leucine and valine (2 millimolar each). The strong light stimulation of amino acid formation illustrates the point that photosynthetic energy is used in situ for amino acid and protein biosynthesis, not solely for CO(2) fixation.
Collapse
|
25
|
A rapid method for isolation of purified, physiologically active chloroplasts, used to study the intracellular distribution of amino acids in pea leaves. PLANTA 1980; 148:75-83. [PMID: 24311269 DOI: 10.1007/bf00385445] [Citation(s) in RCA: 82] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1979] [Accepted: 11/13/1979] [Indexed: 05/12/2023]
Abstract
A procedure is described for the rapid (<5 min) isolation of purified, physiologically active chloroplasts from Pisum sativum L. Mitochondrial and microbody contamination is substantially reduced and broken chloroplasts are excluded by washing through a layer containing a treated silica sol. On average the preparations contain 93% intact chloroplasts and show high rates of (14)CO2 fixation and CO2-dependent O2 evolution (over 100 μmol/mg chlorophyll(chl)/h); they are also able to carry out light-driven incorporation of leucine into protein (4 nmol/mg chl/h). The amino-acid contents of chloroplasts prepared from leaves and from leaf protoplasts have been determined. Asparagine is the most abundant amino acid in the pea chloroplast (>240 nmol/mg chl), even thought it is proportionately lower in the chloroplast relative to the rest of the cell. The chloroplasts contain about 20% of many of the amino acids of the cell, but for individual amino acids the percentage in the chloroplast ranges from 8 to 40% of the cell total. Glutamic acid, glutamine and aspartic acid are enriched in the chloroplasts, while asparagine, homoserine and β-(isoxazolin-5-one-2-yl)-alanine are relatively lower. Leakage of amino acids from the chloroplast during preparation or repeated washing was ca. 20%. Some differences exist between the amino-acid composition of chloroplasts isolated from intact leaves and from protoplasts. In particular, γ-aminobutyric acid accumulates to high levels, while homoserine and glutamic acid decrease, during protoplast formation and breakage.
Collapse
|
26
|
|
27
|
|
28
|
The isolation of a lysine-sensitive aspartate kinase from pea leaves and its involvement in homoserine biosynthesis in isolated chloroplasts. FEBS Lett 1979; 98:165-8. [PMID: 218838 DOI: 10.1016/0014-5793(79)80175-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|