North Korean Missile Proliferation Threat on Northeast Asian Security: American Perception and Strategies

( Jeffrey A. Isaacson ) 국방대학교 안보문제연구소 1999 The Korean Journal of Security Affairs Vol.4 No.-

The pig gut microbial diversity: Understanding the pig gut microbial ecology through the next generation high throughput sequencing

Kim, H.B.,Isaacson, R.E. Elsevier Scientific Pub. Co 2015 Veterinary microbiology Vol.177 No.3

The importance of the gut microbiota of animals is widely acknowledged because of its pivotal roles in the health and well being of animals. The genetic diversity of the gut microbiota contributes to the overall development and metabolic needs of the animal, and provides the host with many beneficial functions including production of volatile fatty acids, re-cycling of bile salts, production of vitamin K, cellulose digestion, and development of immune system. Thus the intestinal microbiota of animals has been the subject of study for many decades. Although most of the older studies have used culture dependent methods, the recent advent of high throughput sequencing of 16S rRNA genes has facilitated in depth studies exploring microbial populations and their dynamics in the animal gut. These culture independent DNA based studies generate large amounts of data and as a result contribute to a more detailed understanding of the microbiota dynamics in the gut and the ecology of the microbial populations. Of equal importance, is being able to identify and quantify microbes that are difficult to grow or that have not been grown in the laboratory. Interpreting the data obtained from this type of study requires using basic principles of microbial diversity to understand importance of the composition of microbial populations. In this review, we summarize the literature on culture independent studies of the pig gut microbiota with an emphasis on its succession and alterations caused by diverse factors.

Dynamic Response Analysis of Slender Marine Structures under Vessel Motion and Regular Waves

Chung-Son Ryu(류정선),Michael Isaacson(마이클 아이잭슨) 한국해안해양공학회 1998 한국해안해양공학회 논문집 Vol.10 No.2

An Algorithm for Applying Multiple Currents Using Voltage Sources in Electrical Impedance Tomography

Myoung Hwan Choi,Tzu-Jen Kao,David Isaacson,Gary J. Saulnier,Jonathan C. Newell 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.4

A method to produce a desired current pattern in a multiple-source EIT system using voltage sources is presented. Application of current patterns to a body is known to be superior to the application of voltage patterns in terms of high spatial frequency noise suppression, resulting in high accuracy in conductivity and permittivity images. Since current sources are difficult and expensive to build, the use of voltage sources to apply the current pattern is desirable. An iterative algorithm presented in this paper generates the necessary voltage pattern that will produce the desired current pattern. The convergence of the algorithm is shown under the condition that the estimation error of the linear mapping matrix from voltage to current is small. Simulation results are presented to illustrate the convergence of the output current.

Association of Obesity with Serum Leptin, Adiponectin, and Serotonin and Gut Microflora in Beagle Dogs

Park, H.‐,J.,Lee, S.‐,E.,Kim, H.‐,B.,Isaacson, R.E.,Seo, K.‐,W.,Song, K.‐,H. John Wiley and Sons Inc. 2015 Journal of veterinary internal medicine Vol.29 No.1

<P><B>Background</B></P><P>Serotonin (5‐hydroxytryptamine, 5HT) is involved in hypothalamic regulation of energy consumption. Also, the gut microbiome can influence neuronal signaling to the brain through vagal afferent neurons. Therefore, serotonin concentrations in the central nervous system and the composition of the microbiota can be related to obesity.</P><P><B>Objective</B></P><P>To examine adipokine, and, serotonin concentrations, and the gut microbiota in lean dogs and dogs with experimentally induced obesity.</P><P><B>Animals</B></P><P>Fourteen healthy Beagle dogs were used in this study.</P><P><B>Methods</B></P><P>Seven Beagle dogs in the obese group were fed commercial food ad libitum, over a period of 6 months to increase their weight and seven Beagle dogs in lean group were fed a restricted amount of the same diet to maintain optimal body condition over a period of 6 months. Peripheral leptin, adiponectin, 5HT, and cerebrospinal fluid (CSF‐5HT) levels were measured by ELISA. Fecal samples were collected in lean and obese groups 6 months after obesity was induced. Targeted pyrosequencing of the 16S rRNA gene was performed using a Genome Sequencer FLX plus system.</P><P><B>Results</B></P><P>Leptin concentrations were higher in the obese group (1.98 ± 1.00) compared to those of the lean group (1.12 ± 0.07, <I>P</I> = .025). Adiponectin and 5‐hydroytryptamine of cerebrospinal fluid (CSF‐5HT) concentrations were higher in the lean group (27.1 ± 7.28) than in the obese group (14.4 ± 5.40, <I>P</I> = .018). Analysis of the microbiome revealed that the diversity of the microbial community was lower in the obese group. Microbes from the phylum Firmicutes (85%) were predominant group in the gut microbiota of lean dogs. However, bacteria from the phylum Proteobacteria (76%) were the predominant group in the gut microbiota of dogs in the obese group.</P><P><B>Conclusions and Clinical Importance</B></P><P>Decreased 5HT levels in obese group might increase the risk of obesity because of increased appetite. Microflora enriched with gram‐negative might be related with chronic inflammation status in obese dogs.</P>

Intestinal Microbial Dysbiosis in Beagles Naturally Infected with Canine Parvovirus

( Jun Seok Park ),( Robin B. Guevarra ),( Bo-ra Kim ),( Jun Hyung Lee ),( Sun Hee Lee ),( Jae Hyoung Cho ),( Hyeri Kim ),( Jin Ho Cho ),( Minho Song ),( Ju-hoon Lee ),( Richard E. Isaacson ),( Kun Ho 한국미생물생명공학회(구 한국산업미생물학회) 2019 Journal of microbiology and biotechnology Vol.29 No.9

Canine parvoviral enteritis (PVE) is an important intestinal disease of the puppies; however, the potential impact of the canine parvovirus (CPV) on the gut microbiota has not been investigated. Therefore, the aim of this study was to evaluate the gut microbial shifts in puppies naturally infected with CPV. Fecal samples were collected from healthy dogs and those diagnosed with PVE at 4, 6, 8, and 12 weeks of age. The distal gut microbiota of dogs was characterized using Illumina MiSeq sequencing of the bacterial 16S rRNA genes. The sequence data were analyzed using QIIME with an Operational Taxonomic Unit definition at a similarity cutoff of 97%. Our results showed that the CPV was associated with significant microbial dysbiosis of the intestinal microbiota. Alpha diversity and species richness and evenness in dogs with PVE decreased compared to those of healthy dogs. At the phylum level, the proportion of Proteobacteria was significantly enriched in dogs with PVE while Bacteroidetes was significantly more abundant in healthy dogs (p < 0.05). In dogs with PVE, Enterobacteriaceae was the most abundant bacterial family accounting for 36.44% of the total bacterial population compared to only 0.21% in healthy puppies. The two most abundant genera in healthy dogs were Prevotella and Lactobacillus and their abundance was significantly higher compared to that of dogs with PVE (p < 0.05). These observations suggest that disturbances of gut microbial communities were associated with PVE in young dogs. Evaluation of the roles of these bacterial groups in the pathophysiology of PVE warrants further studies.

Deciphering Diversity Indices for a Better Understanding of Microbial Communities

( Bo-ra Kim ),( Jiwon Shin ),( Robin B. Guevarra ),( Jun Hyung Lee ),( Doo Wan Kim ),( Kuk-hwan Seol ),( Ju-hoon Lee ),( Hyeun Bum Kim ),( Richard E. Isaacson ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.12

The past decades have been a golden era during which great tasks were accomplished in the field of microbiology, including food microbiology. In the past, culture-dependent methods have been the primary choice to investigate bacterial diversity. However, using culture-independent high-throughput sequencing of 16S rRNA genes has greatly facilitated studies exploring the microbial compositions and dynamics associated with health and diseases. These culture-independent DNA-based studies generate large-scale data sets that describe the microbial composition of a certain niche. Consequently, understanding microbial diversity becomes of greater importance when investigating the composition, function, and dynamics of the microbiota associated with health and diseases. Even though there is no general agreement on which diversity index is the best to use, diversity indices have been used to compare the diversity among samples and between treatments with controls. Tools such as the Shannon- Weaver index and Simpson index can be used to describe population diversity in samples. The purpose of this review is to explain the principles of diversity indices, such as Shannon- Weaver and Simpson, to aid general microbiologists in better understanding bacterial communities. In this review, important questions concerning microbial diversity are addressed. Information from this review should facilitate evidence-based strategies to explore microbial communities.

The dynamics of the piglet gut microbiome during the weaning transition in association with health and nutrition

Guevarra, Robin B.,Hong, Sang Hyun,Cho, Jin Ho,Kim, Bo-Ra,Shin, Jiwon,Lee, Jun Hyung,Kang, Bit Na,Kim, Young Hwa,Wattanaphansak, Suphot,Isaacson, Richard E.,Song, Minho,Kim, Hyeun Bum BioMed Central 2018 Journal of animal science and biotechnology Vol.9 No.-

<P><B>Background</B></P><P>Understanding the composition of the microbial community and its functional capacity during weaning is important for pig production as bacteria play important roles in the pig’s health and growth performance. However, limited information is available regarding the composition and function of the gut microbiome of piglets in early-life. Therefore, we performed 16S rRNA gene and whole metagenome shotgun sequencing of DNA from fecal samples from healthy piglets during weaning to measure microbiome shifts, and to identify the potential contribution of the early-life microbiota in shaping piglet health with a focus on microbial stress responses, carbohydrate and amino acid metabolism.</P><P><B>Results</B></P><P>The analysis of 16S rRNA genes and whole metagenome shotgun sequencing revealed significant compositional and functional differences between the fecal microbiome in nursing and weaned piglets. The fecal microbiome of the nursing piglets showed higher relative abundance of bacteria in the genus <I>Bacteroides</I> with abundant gene families related to the utilization of lactose and galactose. <I>Prevotella</I> and <I>Lactobacillus</I> were enriched in weaned piglets with an enrichment for the gene families associated with carbohydrate and amino acid metabolism. In addition, an analysis of the functional capacity of the fecal microbiome showed higher abundances of genes associated with heat shock and oxidative stress in the metagenome of weaned piglets compared to nursing piglets.</P><P><B>Conclusions</B></P><P>Overall, our data show that microbial shifts and changes in functional capacities of the piglet fecal microbiome resulted in potential reductions in the effects of stress, including dietary changes that occur during weaning. These results provide us with new insights into the piglet gut microbiome that contributes to the growth of the animal.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (10.1186/s40104-018-0269-6) contains supplementary material, which is available to authorized users.</P>

Piglet gut microbial shifts early in life: causes and effects

Guevarra, Robin B.,Lee, Jun Hyung,Lee, Sun Hee,Seok, Min-Jae,Kim, Doo Wan,Kang, Bit Na,Johnson, Timothy J.,Isaacson, Richard E.,Kim, Hyeun Bum BioMed Central 2019 Journal of animal science and biotechnology Vol.10 No.1

<P>The gut microbiome has long been known to play fundamentally important roles in the animal health and the well-being of its host. As such, the establishment and maintenance of a beneficial gut microbiota early in life is crucial in pigs, since early gut colonizers are pivotal in the establishment of permanent microbial community structures affecting the health and growth performance of pigs later in life. Emphasizing this importance of early gut colonizers, it is critical to understand the factors impacting the establishment of the piglet gut microbiome at weaning. Factors include, among others, diet, in-feed antibiotics, probiotics and prebiotic administration. The impact of these factors on establishment of the gut microbiome of piglets at weaning includes effects on piglet gut microbial diversity, structure, and succession. In this review, we thoroughly reviewed the most recent findings on the piglet gut microbiome shifts as influenced by weaning, and how these microbiome changes brought about by various factors that have been shown to affect the development of microbiota in piglets. This review will provide a general overview of recent studies that can help to facilitate the design of new strategies to modulate the gut microbiome in order to enhance gastrointestinal health, growth performance and well-being of piglets.</P>