ABSTRACT
The Hyrcanian forest in northern Iran is threatened by human use and encroachment and has suffered degradation in some areas. The forest has been declared a World Heritage Site and management in the region is shifting from timber production to conservation. There is considerable interest in developing a greater understanding of these diverse forest communities to inform forest management and multiple use plans to maintain the diversity and resilience of these forests. The Hyrcanian forest is characterized by a complex topography of catenas ranging up mountain slopes. Topographic gradients greatly influence microhabitat conditions which in turn impact tree distribution. To date there has been limited research on the impacts of this diverse topography on the spatial distribution of tree species and tree diameters in Hyrcanian forests. Such information is necessary to better understand the regional traits of tree diameters in these natural mixed temperate forests before forest management occurs. We examined the influence of the area's catena topography on the spatial pattern of tree species and on species stand structure in terms of tree diameter distribution. To quantify these dynamics, we conducted a complete enumeration inventory of all trees with dbh >12 cm within a 7.947 ha study area that included three C-shaped (concave) and three V-shaped (convex) catenas. Geostatistical variogram analysis and Clark and Evans aggregation index were utilized to study the spatial distribution of tree diameters. Beech, alder, hornbeam, linden and Persian maple exhibited clustered patterns, and sour cherry, ash, and oak exhibited random patterns. Geostatistical analysis clearly revealed the substantial influence of catena topography on the diameter distributions of alder and linden, more subtle influence on the diameter distributions of beech, and a possible influence on Persian maple, providing valuable insight into stand structure over neighborhood-based indices alone. Alder and linden both exhibited strong spatial structure in their diameter distributions (56% and 86%, respectively) where their diameter was strongly correlated with trees within 108 m and 83 m, respectively, sharing more similar diameters to each other than trees beyond that distance. Beech, maple, and hornbeam exhibited very weak if any spatial structure over short distances. These findings can be used to support the alignment of forest management practices in managed Hyrcanian forests with goals of protecting and maintaining biodiversity and sustainable forest ecosystems, and to inform geospatial modeling of species diameter distributions in areas where a complete stem-map is not feasible.
Subject(s)
Fagus , Trees , Betulaceae , Ecosystem , Forests , Humans , IranABSTRACT
The low image acquisition speed of terahertz (THz) time-domain imaging systems limits their application in biological products analysis. In the current study, a local pixel graph neural network was built for THz time-domain imaging super-resolution. The method could be applied to the analysis of any heterogeneous biological products as it only required a small number of sample images for training and particularly it focused on THz feature frequencies. The graph network applied the Fourier transform to graphs extracted from low-resolution (LR) images bringing an invariance of rotation and flip for local pixels, and the network then learnt the relationship between the state of graphs and the corresponding pixels to be reconstructed. With wood cores and seeds as examples, the images of these samples were captured by a THz time-domain imaging system for training and analysed by the method, achieving the root mean square error (RMSE) of pixels of 0.0957 and 0.1061 for the wood core and seed images, respectively. In addition, the reconstructed high-resolution (HR) images, LR images and true HR images at several feature frequencies were also compared in the current study. Results indicated that the method could not only reconstruct the spatial details and the useful signals from high noise signals at high feature frequencies but could also operate super-resolution in both spatial and spectral aspects.
Subject(s)
Biological Products , Neural Networks, ComputerABSTRACT
Understanding and applying nutrition knowledge and skills to all aspects of health care are extremely important, and all health care professions need basic training to effectively assess dietary intake and provide appropriate guidance, counseling, and treatment to their patients. With obesity rates at an all-time high and the increasing prevalence of diabetes projected to cost the Federal government billions of dollars, the need for interprofessional nutrition education is paramount. Physicians, physician assistants, nurses, nurse practitioners, pharmacists, dentists, dental hygienists, occupational therapists, physical therapists, speech and language pathologists, and others can positively affect patient care by synchronizing and reinforcing the importance of nutrition across all specialty areas. Although nutrition is a critical component of acute and chronic disease management, as well as health and wellness across the health care professions, each profession must reevaluate its individual nutrition-related professional competencies before the establishment of meaningful interprofessional collaborative nutrition competencies. This article discusses gaps in nutrition education and training within individual health professions (ie, nursing, pharmacy, dentistry, and dietetics) and offers suggestions for educators, clinicians, researchers, and key stakeholders on how to build further capacity within the individual professions for basic and applied nutrition education. This "gaps methodology" can be applied to all health professions, including physician assistants, physical therapists, speech and language pathologists, and occupational therapists.
Subject(s)
Education, Medical/methods , Health Personnel/education , Nutritional Sciences/education , Humans , Nutrition Therapy , Nutritionists/educationABSTRACT
This study accumulated European consumer attitudes towards processed meats and their use as a functional food. A survey was set up using an online web-application to gather information on consumer perception of processed meats as well as neutraceutical-containing processed meats. 548 responses were obtained and statistical analysis was carried out using a statistical software package. Data was summarized as frequencies for each question and statistical differences analyzed using the Chi-Square statistical test with a significance level of 5% (P<0.05). The majority of consumer attitudes towards processed meat indicate that they are unhealthy products. Most believe that processed meats contain large quantities of harmful chemicals, fat and salt. Consumers were found to be very pro-bioactive compounds in yogurt style products but unsure of their feelings in meat based products, which is likely due to the lack of familiarity to these products. Many of the respondents were willing to consume meat based functional foods but were not willing to pay more for them.
Subject(s)
Attitude , Consumer Behavior , Dietary Supplements , Foods, Specialized , Health , Meat Products , Ubiquinone/analogs & derivatives , Adolescent , Adult , Chi-Square Distribution , Data Collection , Europe , Female , Functional Food , Humans , Male , Middle Aged , Surveys and Questionnaires , Young AdultABSTRACT
The use of CoQ10 fortification in the production of a functional food has been demonstrated in the past but primarily for dairy products. This study aimed to determine the bio-accessibility of CoQ10 in processed meat products, beef patties and pork breakfast sausages, fortified with CoQ10. Both the patties and sausages were fortified with a micellarized form of CoQ10 to enhance solubility to a concentration of 1mg/g of sample (NovaSolQ®). An assay was developed combining in vitro digestion and HPLC analysis to quantify the CoQ10 present in fortified products (100mg/g). The cooking retention level of CoQ10 in the products was found to be 74±1.42% for patties and 79.69±0.75% for sausages. The digestibility for both products ranged between 93% and 95%, sausages did have a higher digestibility level than patties but this was not found to be significant (P<0.01).
Subject(s)
Food, Fortified/analysis , Meat Products/analysis , Ubiquinone/analogs & derivatives , Animals , Cattle , Cooking , Digestion , Hot Temperature , Humans , Models, Biological , Swine , Ubiquinone/chemistry , Ubiquinone/metabolismABSTRACT
Silver fir is one of the most productive and ecologically valuable native European tree species, however, it has been experiencing decline which has periodically occurred over its natural range. This paper aims to investigate the recent climate-growth relationships of silver fir (Abies alba Mill.) and its temporal change along the course of its life. Long-term tree-ring databases, as well as records on climate, atmospheric SO2, NO3 and acid concentrations from four different regions in the Western Carpathians were used. The results provide clear evidence of significant increase of silver fir's radial increment over the entire Western Carpathian area since 1970-1980. The results indicated that the most probable factors behind the rapid recovery of tree radial increment were reductions in emissions of NO3 and SO2, alongside a significant increase in mean June, July and April temperatures.
Subject(s)
Abies/growth & development , Air Pollutants/analysis , Nitrates/analysis , Sulfur Dioxide/analysis , Air Pollution/statistics & numerical data , Climate , Climate Change , Ecology , Environmental Monitoring , TemperatureABSTRACT
The sensory and physiochemical properties of sausages with varying fat and salt levels were investigated. Twenty eight sausages were produced with varying concentrations of fat (22.5%, 27.5%, 32.5%, 37.5% w/w) and salt (0.8%, 1%, 1.2%, 1.4%, 1.6%, 2%, 2.4% w/w). Sausages were assessed instrumentally for colour, moisture, fat, cooking loss and texture profile analysis. Consumers (n = 25), evaluated each product in duplicate for colour, texture, tenderness, juiciness, salt taste, meat flavour, off-flavour and overall acceptability using a hedonic scale. Lowering fat produced products which consumers rated as less dark in colour, tougher, less juicy and taste less salty than higher fat products. However, no significant preferred sample was found amongst consumers. Salt reduction in products produced sausages which consumers rated as paler in colour, more tender and with greater meat flavour than higher salt containing products. The sausages containing 1.4% and 1.0% salt were significantly (P<0.01) found to be more acceptable to consumers than other salt levels.
Subject(s)
Chemical Phenomena , Dietary Fats/analysis , Meat Products/analysis , Sodium, Dietary/analysis , Taste , Adult , Animals , Breakfast , Color , Consumer Behavior , Cooking , Food Preferences , Humans , Swine , Young AdultABSTRACT
The sensory and physiochemical properties of frankfurters with varying fat and salt levels were investigated. Twenty frankfurter formulations were produced with varying concentrations of fat (10%, 15%, 20%, 25% w/w) and salt (1%, 1.5%, 2%, 2.5%, 3% w/w). Frankfurters were assessed instrumentally for colour, moisture, fat, cooking loss and texture profile analysis. Consumers (n=25) evaluated each product in duplicate for colour, coarseness, tenderness, juiciness, salt taste, meat flavour, off-flavour and overall acceptability using a hedonic scale. Salt levels below 1.5% were shown to have a negative effect on consumer acceptability, with 2.5% salt concentration being the most accepted (P<0.001) by consumers. However, frankfurters containing the lower fat levels 10% and 15% fat with higher salt levels (2.5-3%) were significantly the most acceptable variants to consumers. Samples containing less fat and salt were found to be tougher, less juicy and had greater cooking losses. Thus salt perception is very important for consumer acceptability, but fat levels can be potentially reduced without significantly affecting overall acceptability.
Subject(s)
Diet, Fat-Restricted , Diet, Sodium-Restricted , Dietary Fats/analysis , Fast Foods/analysis , Food Quality , Meat Products/analysis , Sodium Chloride, Dietary/analysis , Adult , Animals , Cattle , Chemical Phenomena , Consumer Behavior , Diet/ethnology , Dietary Fats/administration & dosage , Dietary Fats/adverse effects , Food Preferences , Humans , Ireland , Mechanical Phenomena , Principal Component Analysis , Sensation , Sodium Chloride, Dietary/administration & dosage , Sodium Chloride, Dietary/adverse effects , Sus scrofa , Water/analysis , Young AdultABSTRACT
The interactive effects of varying levels of salt and fat on the sensory and physiochemical properties of beef patties were investigated. Twenty beef patties with varying levels of fat (30% 40% 50% 60% w/w) and salt (0.5%, 0.75% 1.0% 1.25% 1.5% w/w) were manufactured. All samples were assessed instrumentally for colour, moisture, fat, cooking loss and texture profile analysis. Sensory consumer evaluation was conducted using 25 consumers. The consumers rated each coded product, in duplicate, in terms of colour, texture, tenderness, juiciness, salt, taste, meat flavour, off flavour and overall acceptability. The data indicate that the most consumer acceptable beef patty was that containing 40% fat with a salt level of 1%. This is a 20% decrease in fat and a 50% decrease in salt levels when compared to commercial patties available in Ireland and the UK.
Subject(s)
Consumer Behavior , Dietary Fats , Food Handling/methods , Food Preferences , Meat Products/analysis , Sodium Chloride, Dietary , Taste , Adult , Color , Humans , Young AdultABSTRACT
INTRODUCTION: Hypokinesia is associated with spaceflight and prolonged illnesses and may lead to secondary immune deficiency. METHODS: The distribution of immunocytes in whole blood, mitogen-induced cytokine secretion in vitro, Epstein-Barr virus (EBV) reactivation, and plasma cortisol levels were studied in 13 healthy volunteers subjected to a horizontal bed rest (BR) regime for 28 d. Samples were collected before the study, weekly during BR, and then 3-5 d after the regime ended. Additionally, subjects were treated with hydrocortisone on the 1st and 27th d of BR to simulate the hypercortisolemia that occurs during stress. RESULTS: The factors of 28-d BR regime accompanied by acute hypercortisolemia significantly decreased the relative and absolute number of total lymphocytes, CD3+ T-cells, T-helper subset, and monocytes, but increased the percentage of the CD8+ T-cells, and NK cells at the 4th wk compared with the baseline. A significant decrease in mitogen-activated secretion of IL-2, IFN-gamma, TNF-beta, IL-6, and IL-10 was registered at the same interval. Also, secretion of IL-2 and IFN-gamma declined at the 2nd week of the BR regime. Secretion of IL-4 was significantly higher at the 2nd and 3rd weeks compared with the baseline. A significant increase in the shedding of EBV DNA in saliva was observed as early as the 3rd wk of BR. CONCLUSIONS: Stress factors associated with BR significantly alter immune responsiveness in vitro and in vivo. Changes in the cytokine secretion and cytokine imbalance precede latent EBV reactivation. PHA/LPS-activated cytokine secretion in whole blood can be used as a test system for predicting latent virus activation.
Subject(s)
Cytokines/metabolism , Herpesvirus 4, Human/immunology , Immobilization/adverse effects , Immobilization/physiology , Virus Activation/immunology , Adult , Amino Acids, Essential/immunology , Amino Acids, Essential/metabolism , Anti-Inflammatory Agents/immunology , Anti-Inflammatory Agents/pharmacology , Cytokines/drug effects , Dietary Supplements , Humans , Hydrocortisone/blood , Hydrocortisone/immunology , Middle Aged , Saliva/virology , Space Simulation/adverse effects , Stress, Psychological/immunology , Stress, Psychological/virology , Virus Latency/immunology , Virus Latency/physiologyABSTRACT
OBJECTIVES: The purpose of this study was to determine the feasibility of implementing a diabetes prevention program (DPP) in a rural African-American church. METHODS: A six-session DPP, modeled after the successful National Institutes of Health (NIH) DPP, was implemented in a rural African-American church. Adult members of the church identified as high risk for diabetes, based on results of a risk questionnaire, were screened with a fasting glucose. Persons with prediabetes, a fasting glucose of 100-125 mg/dL, participated in the six-session, Lifestyle Balance Church DPP. The primary outcomes were attendance rates and changes in fasting glucose, weight and body mass index measured at baseline, six- and 12-month follow-up. RESULTS: Ninety-nine adult church members were screened for diabetes risk. Eleven had impaired fasting glucose. Ten of 11 participated in the six-session intervention, for an attendance rate of 78%. After the intervention and 12-month follow-up, there was a mean weight loss of 7.9 lbs and 10.6 lbs, respectively. CONCLUSIONS: This pilot project suggests that a modified six-session DPP can be translated to a group format and successfully implemented in a church setting. Further randomized studies are needed to determine the effectiveness of such an intervention.
Subject(s)
Black or African American/education , Diabetes Mellitus/ethnology , Diabetes Mellitus/prevention & control , Health Behavior/ethnology , Health Education/organization & administration , Models, Educational , Program Development/methods , Religion and Medicine , Rural Health Services/organization & administration , Adolescent , Adult , Female , Georgia , Humans , Life Style , Male , Mass Screening , Middle Aged , Pilot Projects , Risk Assessment , Surveys and QuestionnairesABSTRACT
OBJECTIVE: To determine the impact of a simple nurse-based prompt on fasting glucose screening and counseling regarding diet, exercise and weight loss to persons at increased risk for type 2 diabetes. RESEARCH DESIGN AND METHODS: Patients at risk for diabetes were recruited from 10 primary care practices. Nurses were trained to score a diabetes risk assessment and prompt providers concerning all high-risk subjects. Both univariate and multivariate logistic regression models were used to determine the association between the nurse prompt and subsequent fasting glucose testing or receiving advice for diet, exercise, or weight loss. RESULTS: Of 1176 subjects, 597 were recruited from intervention practices and 579 from control practices. In both the univariate and multivariate models, the intervention group was more likely to receive fasting glucose testing and advice for diet, exercise and weight loss. In the multivariate model, patients in the intervention group were more likely to receive fasting glucose testing (odds ratio 9.3, 95% confidence interval 3.6-24.0), dietary advice (6.1, 3.5-10.7), exercise advice (7.4, 4.0-13.9), and weight loss advice (1.9, 1.1-3.7). CONCLUSIONS: A simple nurse-based prompt is an effective tool to increase screening and preventive services for people at risk for type 2 diabetes.
Subject(s)
Counseling , Diabetes Mellitus/epidemiology , Diabetes Mellitus/prevention & control , Mass Screening , Nurses , Analysis of Variance , Education, Nursing, Continuing , Humans , Multivariate Analysis , Risk FactorsABSTRACT
RATIONALE AND OBJECTIVES: To promote active learning in an introductory Radiologic Anatomy course through the use of computer-based exercises. MATERIALS AND METHODS: DICOM datasets from our hospital PACS system were transferred to a networked cluster of desktop computers in a medical school classroom. Medical students in the Radiologic Anatomy course were divided into four small groups and assigned to work on a clinical case for 45 minutes. The groups used iPACS viewer software, a free DICOM viewer, to view images and annotate anatomic structures. The classroom instructor monitored and displayed each group's work sequentially on the master screen by running SynchronEyes, a software tool for controlling PC desktops remotely. RESULTS: Students were able to execute the assigned tasks using the iPACS software with minimal oversight or instruction. Course instructors displayed each group's work on the main display screen of the classroom as the students presented the rationale for their decisions. The interactive component of the course received high ratings from the students and overall course ratings were higher than in prior years when the course was given solely in lecture format. CONCLUSIONS: DICOM viewing software is an excellent tool for enabling students to learn radiologic anatomy from real-life clinical datasets. Interactive exercises performed in groups can be powerful tools for stimulating students to learn radiologic anatomy.
Subject(s)
Anatomy/education , Computer-Assisted Instruction/methods , Computer-Assisted Instruction/statistics & numerical data , Consumer Behavior , Radiology/education , Software , Students, Medical/statistics & numerical data , California , Curriculum , Education, Medical/methods , Education, Medical/statistics & numerical data , Educational Measurement , Professional Competence , Software Validation , User-Computer InterfaceABSTRACT
Tissue restoration is the process whereby multiple damaged cell types are replaced to restore the histoarchitecture and function to the tissue. Several theories have been proposed to explain the phenomenon of tissue restoration in amphibians and in animals belonging to higher orders. These theories include dedifferentiation of damaged tissues, transdifferentiation of lineage-committed progenitor cells, and activation of reserve precursor cells. Studies by Young et al. and others demonstrated that connective tissue compartments throughout postnatal individuals contain reserve precursor cells. Subsequent repetitive single cell-cloning and cell-sorting studies revealed that these reserve precursor cells consisted of multiple populations of cells, including tissue-specific progenitor cells, germ-layer lineage stem cells, and pluripotent stem cells. Tissue-specific progenitor cells display various capacities for differentiation, ranging from unipotency (forming a single cell type) to multipotency (forming multiple cell types). However, all progenitor cells demonstrate a finite life span of 50 to 70 population doublings before programmed cell senescence and cell death occurs. Germ-layer lineage stem cells can form a wider range of cell types than a progenitor cell. An individual germ-layer lineage stem cell can form all cells types within its respective germ-layer lineage (i.e., ectoderm, mesoderm, or endoderm). Pluripotent stem cells can form a wider range of cell types than a single germ-layer lineage stem cell. A single pluripotent stem cell can form cells belonging to all three germ layer lineages. Both germ-layer lineage stem cells and pluripotent stem cells exhibit extended capabilities for self-renewal, far surpassing the limited life span of progenitor cells (50-70 population doublings). The authors propose that the activation of quiescent tissue-specific progenitor cells, germ-layer lineage stem cells, and/or pluripotent stem cells may be a potential explanation, along with dedifferentiation and transdifferentiation, for the process of tissue restoration. Several model systems are currently being investigated to determine the possibilities of using these adult quiescent reserve precursor cells for tissue engineering.
Subject(s)
Cell Differentiation/physiology , Germ Layers/cytology , Pluripotent Stem Cells/cytology , Regeneration/physiology , Tissue Engineering , Transcription Factors , Animals , Antigens, Surface/metabolism , Bone and Bones/metabolism , Cattle , Cell Lineage/physiology , Cellular Senescence/physiology , Connective Tissue/physiology , DNA-Binding Proteins/metabolism , Diabetes Mellitus/therapy , Embryo, Mammalian , Embryo, Nonmammalian , Extremities/physiology , Genetic Therapy , Hematopoietic Stem Cell Transplantation , Humans , Muscle, Skeletal/metabolism , Muscle, Skeletal/transplantation , Myocardial Infarction/therapy , Myogenin/metabolism , Neurodegenerative Diseases/therapy , Octamer Transcription Factor-3 , Pluripotent Stem Cells/transplantation , Rats , Telomerase/metabolism , Urodela/growth & development , Urodela/physiologyABSTRACT
Undifferentiated cells have been identified in the prenatal blastocyst, inner cell mass, and gonadal ridges of rodents and primates, including humans. After isolation these cells express molecular and immunological markers for embryonic cells, capabilities for extended self-renewal, and telomerase activity. When allowed to differentiate, embryonic stem cells express phenotypic markers for tissues of ectodermal, mesodermal, and endodermal origin. When implanted in vivo, undifferentiated noninduced embryonic stem cells formed teratomas. In this report we describe a cell clone isolated from postnatal rat skeletal muscle and derived by repetitive single-cell clonogenic analysis. In the undifferentiated state it consists of very small cells having a high ratio of nucleus to cytoplasm. The clone expresses molecular and immunological markers for embryonic stem cells. It exhibits telomerase activity, which is consistent with its extended capability for self-renewal. When induced to differentiate, it expressed phenotypic markers for tissues of ectodermal, mesodermal, and endodermal origin. The clone was designated as a postnatal pluripotent epiblastic-like stem cell (PPELSC). The undifferentiated clone was transfected with a genomic marker and assayed for alterations in stem cell characteristics. No alterations were noted. The labeled clone, when implanted into heart after injury, incorporated into myocardial tissues undergoing repair. The labeled clone was subjected to directed lineage induction in vitro, resulting in the formation of islet-like structures (ILSs) that secreted insulin in response to a glucose challenge. This study suggests that embryonic-like stem cells are retained within postnatal mammals and have the potential for use in gene therapy and tissue engineering.
Subject(s)
Colony-Forming Units Assay/methods , Pluripotent Stem Cells/cytology , Pluripotent Stem Cells/physiology , Animals , Animals, Newborn , Male , Rats , Rats, Inbred WF , Rats, Sprague-Dawley , Stem Cells/cytology , Stem Cells/physiologyABSTRACT
The overall goal of our Nutrition Academic Award (NAA) medical nutrition program at Mercer University School of Medicine is to develop, implement and evaluate a medical education curriculum in nutrition and other aspects of cardiovascular disease (CVD) prevention and patient management with emphasis on the training of primary care physicians for medically underserved populations. The curriculum is 1) vertically integrated throughout all 4 y of undergraduate medical education, including basic science, clinical skills, community science and clinical clerkships as well as residency training; 2) horizontally integrated to include allied healthcare training in dietetics, nursing, exercise physiology and public health; and 3) designed as transportable modules adaptable to the curricula of other medical schools. The specific aims of our program are 1) to enhance our existing basic science problem-based Biomedical Problems Program with respect to CVD prevention through development of additional curriculum in nutrition/diet/exercise and at-risk subpopulations; 2) to integrate into our Clinical Skills Program objectives for medical history taking, conducting patient exams, diet/lifestyle counseling and referrals to appropriate allied healthcare professionals that are specific to CVD prevention; 3) to enhance CVD components in the Community Science population-based medicine curriculum, stressing the health-field concept model, community needs assessment, evidence-based medicine and primary care issues in rural and medically underserved populations; 4) to enhance the CVD prevention and patient management component in existing 3rd- and 4th-y clinical clerkships with respect to nutrition/diet/exercise and socioeconomic issues, behavior modification and networking with allied health professionals; and 5) to integrate a nutrition/behavior change component into Graduate Residency Training in CVD prevention.
Subject(s)
Curriculum , Education, Medical, Undergraduate/methods , Nutritional Sciences/education , Problem-Based Learning/organization & administration , Schools, Medical , Bioethics/education , Georgia , Goals , Physician-Patient RelationsABSTRACT
Nearly three decades of space flight research have suggested that there are subclinical diabetogenic changes that occur in microgravity. Alterations in insulin secretion, insulin sensitivity, glucose tolerance, and metabolism of protein and amino acids support the hypothesis that insulin plays an essential role in the maintenance of muscle mass in extended-duration space flight. Experiments in flight and after flight and ground-based bedrest studies have associated microgravity and its experimental paradigms with manifestations similar to those of diabetes, physical inactivity, and aging. We propose that these manifestations are characterized best by an etiology that falls into the clinical category of "other" causes of diabetes, including, but not restricted to, genetic beta-cell defects, insulin action defects, diseases of the endocrine pancreas, endocrinopathies, drug or chemically induced diabetes, infections, immune-mediated metabolic alteration, and a host of genetic related diseases. We present data showing alterations in tumor necrosis factor-alpha production, insulin secretion, and amino acid metabolism in pancreatic islets of Langerhans cultured in a ground-based cell culture bioreactor that mimics some of the effects of microgravity. Taken together, space flight research, ground-based studies, and bioreactor studies of pancreatic islets of Langerhans support the hypothesis that the pancreas is unable to overcome peripheral insulin resistance and amino acid dysregulation during space flight. We propose that measures of insulin secretion and insulin action will be necessary to design effective countermeasures against muscle loss, and we advance the "disposition index" as an essential model to be used in the clinical management of space flight-induced muscle loss.
Subject(s)
Diabetes Mellitus/etiology , Insulin/metabolism , Islets of Langerhans/metabolism , Space Flight , Weightlessness/adverse effects , Amino Acids/metabolism , Animals , Glucose/metabolism , Humans , Insulin Resistance , Insulin Secretion , Islets of Langerhans/cytology , Muscle Proteins/metabolism , Tumor Necrosis Factor-alpha/metabolism , Tumor Necrosis Factor-alpha/physiologyABSTRACT
Conducting research during actual or simulated weightlessness is a challenging endeavor, where even the simplest activities may present significant challenges. This article reviews some of the potential obstacles associated with performing research during space flight and offers brief descriptions of current and previous space research platforms and ground-based analogs, including those for human, animal, and cell-based research. This review is intended to highlight the main issues of space flight research analogs and leave the specifics for each physiologic system for the other papers in this section.