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Stem cell therapy for the treatment of Leydig cell dysfunction in primary hypogonadism

World journal of Stem Cells 2016年第10期8卷 306-315页

作者： Taylor C Peak Nora M Haney William Wang kenneth j delay Wayne j Hellstrom Department of Urology School of MedicineTulane University

The production of testosterone occurs within the Leydig cells of the testes. When production fails at this level from either congenital, acquired, or systemic disorders,the result is primary hypogonadism. While numerous testosterone formulations have been developed, none are yet fully capable of replicating the physiological patterns of testosterone secretion. Multiple stem cell therapies to restore androgenic function of the testes are under investigation. Leydig cells derived from bone marrow, adipose tissue, umbilical cord, and the testes have shown promise for future therapy for primary hypogonadism. In particular, the discovery and utilization of a group of progenitor stem cells within the testes, known as stem Leydig cells(SLCs), has led not only to a better understanding of testicular development, but of treatment as well. When combining this with an understanding of the mechanisms that lead to Leydig cell dysfunction, researchers and physicians will be able to develop stem cell therapies that target the specific step in the steroidogenic process that is deficient. The current preclinical studies highlight the complex nature of regenerating this steroidogenic process and the problems remain unresolved. In summary, there appears to be two current directions for stem cell therapy in male primary hypogonadism. The first method involves differentiating adult Leydig cells from stem cells of various origins from bone marrow, adipose, or embryonic sources. The second method involves isolating, identifying, and transplanting stem Leydig cells into testicular tissue. Theoretically, in-vivo re-activation of SLCs in men with primary hypogonadism due to age would be another alternative method to treat hypogonadism while eliminating the need for transplantation.

关键词： Stem cell therapy Leydig cells Primary hypogonadism Stem Leydig cells Testosterone Bone marrow-derived stem cells Adipose-derived mesenchymal stem cells

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Diabetes mellitus as a risk factor for gastrointestinal cancer among American veterans

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World journal of Gastroenterology 2009年第42期15卷 5274-5278页

作者： M Mazen jamal Eugene j Yoon kenneth j Vega Mehrtash Hashemzadeh kenneth j Chang Division of Gastroenterology Veterans Affairs(VA) Medical CenterLong BeachCA 90822United States Division of Gastroenterology Department of Internal MedicineCollege of MedicineUniversity of CaliforniaIrvine Medical CenterOrangeCA 92868United States Division of Gastroenterology University of Florida/JacksonvilleJacksonvilleFL 32207United States

AIM:To assess the risk of biliary and pancreatic cancers in a large cohort of patients with type 2 diabetes mellitus(DM) .METHODS:Eligibility for this study included patients with type 2 DM(ICD-9 code 250.0) who were discharged from Department of Veteran Affairs hospitals between 1990 and ***-matched control patients without DM were selected from the same patient treatment files during the same *** information included age,sex and *** diagnoses included known risk factors based on their ICD-9 *** multivariate logistic regression,the occurrence of biliary and pancreatic cancer was compared between case subjects with DM and controls without ***:A total of 1172496 case and control subjects were *** mean age for study and control subjects was 65.8 ± 11.3 and 64.8 ± 12.6 years,*** frequency of pancreatic cancer in subjects with DM was increased(0.9%) in comparison to control subjects(0.3%) with an OR of 3.22(95% CI:3.03-3.42) .The incidence of gallbladder andextrahepatic biliary cancers was increased by twofold in diabetic patients when compared to *** OR and 95% CI were 2.20(1.56-3.00) and 2.10(1.61-2.53) ,***:Our study demonstrated that patients with DM have a threefold increased risk for developing pancreatic cancer and a twofold risk for developing biliary cancer.

关键词： Diabetes mellitus Pancreatic neoplasms Adenocarcinoma Gallbladder neoplasms

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Power regulation of kinematic control inputs for forward flying Drosophila

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Acta Mechanica Sinica 2014年第6期30卷 809-818页

作者： kenneth MacFarlane Imraan Faruque j.Sean Humbert 3181 Glenn L Martin Hall University of MarylandCollege Park MD 20742 USA

The choices of insect wing kinematic programs is not well understood,particularly the mechanism by which an insect selects a distortion to achieve flight control.A methodology to evaluate prospective kinematic control inputs is presented based on the reachable states when control actuation was constrained to a unit of *** method implements a computationally-derived reduced order model of the insect’s flight dynamics combined with calculation of power *** kinematic inputs are evaluated based on this criterion for a Drosophila size insect in forward *** bias is shown to be the dominant control input using this power normalized evaluation measure.

关键词： Flight control Control Drosophila Power

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Intraocular lens power calculation in eyes with previous corneal refractive surgery

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Eye and Vision 2018年第1期5卷 172-181页

作者： Giacomo Savini kenneth j.Hoffer G.B.Bietti Eye Foundation RomeItaly. Stein Eye Institute University of CaliforniaLos AngelesCAUSA.3 St.Mary’s Eye CenterSanta MonicaCAUSA

Background:This review aims to explain the reasons why intraocular lens(IOL)power calculation is challenging in eyes with previous corneal refractive surgery and what solutions are currently available to obtain more accurate ***:After IOL implantation in eyes with previous LASIK,PRK or RK,a refractive surprise can occur because (i)the altered ratio between the anterior and posterior corneal surface makes the keratometric index invalid;(ii)the corneal curvature radius is measured out of the optical zone;and (iii)the effective lens position is erroneously predicted if such a prediction is based on the post-refractive surgery corneal *** methods are currently available to obtain the best refractive outcomes in these eyes,even when the perioperative data(*** corneal power and surgically induced refractive change)are not *** this review,we describe the most accurate methods based on our clinical ***:IOL power calculation after myopic corneal refractive surgery can be calculated with a variety of methods that lead to relatively accurate outcomes,with 60 to 70%of eyes showing a prediction error within 0.50 diopters.

关键词： Cataract Intraocular lens power LASIK PRK Excimer laser Corneal surgery Keratometry

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Retrograde jejunoduodenogastric intussusception due to a replacement percutaneous gastrostomy tube presenting as upper gastrointestinal bleeding

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World journal of Gastroenterology 2007年第39期13卷 5282-5284页

作者： Eric Ibegbu Manish Relan kenneth j Vega Divisions of Gastroenterology and General Internal Medicine University of Florida Health Science Center/Jacksonville Jacksonville FL32207 United States

Percutaneous endoscopic gastrostomy (PEG) tube complications can be serious or life threatening. Retrograde intussusception is a very rare complication of PEG tubes with only 9 cases reported in the literature. We describe a case of retrograde intussusception, associated with the use of a Foley catheter as a replacement gastrostomy tube, presenting with upper gastrointestinal bleeding. To our knowledge, this is the first reported case of PEG-related retrograde intussusception successfully managed in a non-surgical manner. Retrograde intussusception likely occurred due to migration of the replacement tube with resultant securing and invagination of the proximal jejunum when the gastrostomy tube was anchored to the abdominal wall.

关键词： Percutaneous endoscopic gastrostomy Intussusception Migration and upper gastrointestinal bleeding

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Characterization of ASTER GDEM elevation data over vegetated area compared with lidar data

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International journal of Digital Earth 2015年第3期8卷 198-211页

作者： Wenjian Ni Guoqing Sun kenneth j.Ranson State Key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital EarthChinese Academy of SciencesBeijingChina Department of Geographical sciences University of MarylandCollege ParkMDUSA Biospheric Sciences Branch NASA’s Goddard Space Flight CenterGreenbeltMDUSA

Current researches based on areal or spaceborne stereo images with very high resolutions(<1 m)have demonstrated that it is possible to derive vegetation height from stereo *** second version of the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model(ASTER GDEM)is the state-of-the-art global elevation data-set developed by stereo ***,the resolution of ASTER stereo images(15 m)is much coarser than areal stereo images,and the ASTER GDEM is compiled products from stereo images acquired over 10 *** forest disturbances as well as forest growth are inevitable in 10 years time *** this study,the features of ASTER GDEM over vegetated areas under both flat and mountainous conditions were investigated by comparisons with lidar *** factors possibly affecting the extraction of vegetation canopy height considered include(1)co-registration of DEMs;(2)spatial resolution of digital elevation models(DEMs);(3)spatial vegetation structure;and(4)terrain *** results show that the accurate coregistration between ASTER GDEM and national elevation dataset(NED)is necessary over mountainous *** correlation between ASTER GDEM minus NED and vegetation canopy height is improved from 0.328 to 0.43 by degrading resolutions from 1 arc-second to 5 arc-second and further improved to 0.6 if only homogenous vegetated areas were considered.

关键词： vegetation canopy height ASTER GDEM NED photogrammetry stereo-mapping

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Uptake and transformation of arsenic during the reproductive life stage of Agaricus bisporus and Agaricus campestris

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journal of Environmental Sciences 2016年第11期28卷 140-149页

作者： Michelle M.Nearing Iris Koch kenneth j.Reimer Environmental Sciences Group Royal Military College of Canada

Fruiting bodies from the Agaricus genus have been found to contain non-toxic arsenobetaine（AB） as a major compound. It is unknown whether AB is formed during the vegetative or reproductive life stages of the fungus, or by the surrounding microbial community, but AB＇s structural similarity to glycine betaine has led to the hypothesis that AB may be adventitiously accumulated as an osmolyte. To investigate the potential formation of AB during the reproductive life stage of Agaricus species, growth substrate and fungi were collected during the commercial growth of Agaricus bisporus and analyzed for arsenic speciation using HPLC-ICP-MS. AB was found to be the major arsenic compound in the fungus at the earliest growth stage of fruiting（the primordium）. The growth substrate mainly contained arsenate（As（V））. The distribution of arsenic in an A. bisporus primordium grown on As（V） treated substrate, and in a mature Agaricus campestris fruiting body collected from arsenic contaminated mine tailings, was mapped using two dimensional XAS imaging. The primordium and stalk of the mature fruiting body were both found to be growing around pockets of substrate material containing higher As concentrations, and AB was found exclusively in the fungal tissues. In the mature A. campestris the highest proportion of AB was found in the cap, supporting the AB as an osmolyte hypothesis. The results have allowed us to pinpoint the fungus life stage at which AB formation takes place,namely reproduction, which provides a direction for further research.

关键词： Arsenobetaine Arsenic Agaricus Fungi HPLC-ICP-MS XAS imaging

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Endoscopic foregut surgery and interventions:The future is *** state-of-the-art and my personal journey

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World journal of Gastroenterology 2019年第1期25卷 1-41页

作者： kenneth j Chang H.H.Chao Comprehensive Digestive Disease Center University of CaliforniaIrvine Medical CenterOrangeCA 92868United States

In this paper, I reviewed the emerging field of endoscopic surgery and present data supporting the contention that endoscopy can now be used to treat many foregut diseases that have been traditionally treated surgically. Within each topic,the content will progress as follows: "lessons learned", "technical considerations"and "future opportunities". Lessons learned will provide a brief background and update on the most current literature. Technical considerations will include my personal experience, including tips and tricks that I have learned over the ***, future opportunities will address current unmet needs and potential new areas of development. The foregut is defined as "the upper part of the embryonic alimentary canal from which the pharynx, esophagus, lung, stomach, liver,pancreas, and part of the duodenum develop". Foregut surgery is well established in treating conditions such as gastroesophageal reflux disease(GERD), achalasia, esophageal diverticula, Barrett's esophagus(BE) and esophageal cancer, stomach cancer, gastric-outlet obstruction, and obesity. Over the past decade, remarkable progress in interventional endoscopy has culminated in the conceptualization and practice of endoscopic foregut surgery for various clinical conditions summarized in this paper. Regarding GERD, there are now several technologies available to effectively treat it and potentially eliminate symptoms, and the need for long-term treatment with proton pump *** the first time, fundoplication can be performed without the need for open or laparoscopic surgery. Long-term data going out 5-10 years are now emerging showing extended durability. In respect to achalasia, per-oral endoscopic myotomy(POEM) which was developed in japan, has become an alternative to the traditional Heller's myotomy. Recent meta-analysis show that POEM may have better results than Heller, but the issue of post-POEM GERD still needs to be addressed. There is now a resurgence of endoscopic tre

关键词： Endoscopy Foregut diseases Gastroesophageal reflux disease Endoscopic sleeve gastroplasty Endoscopic submucosal dissection Per-oral endoscopic myotomy Endo-hepatology

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Comparison of reflux esophagitis and its complications between African Americans and non-Hispanic whites

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World journal of Gastroenterology 2009年第23期15卷 2878-2881页

作者： kenneth j Vega Sian Chisholm M Mazen jamal Divisions of Gastroenterology and General Internal Medicine University of Florida Health Sciences Center Jacksonville Florida 32207 United States Gastroenterology Section Veterans Affairs Medical Center 5901 E. 7th St. Long Beach CA 90822 United States

AIM: To determine the effect of ethnicity on the severity of reflux esophagitis (RE) and its complications. METHODS: A retrospective search of the endoscopy database at the University of Florida Health Science Center/jacksonville for all cases of reflux esophagitis and its complications from january 1 to March 31, 2001 was performed. Inclusion criteria were endoscopic evidence of esophagitis using the LA classif ication, reflux related complications and self-reported ethnicity. The data obtained included esophagitis grade, presence of a hiatal hernia, esophageal ulcer, stricture and Barrett's esophagus, and endoscopy indication. RESULTS: The search identified 259 patients with RE or its complications, of which 171 were non-Hispanic whites and 88 were African Americans. The mean ages and male/female ratios were similar in the two groups. RE grade, esophageal ulcer, stricture and hiatal hernia frequency were likewise similar in the groups. Barrett's esophagus was present more often in non-Hispanic whites than in African Americans (15.8% vs 4.5%; P < 0.01). Heartburn was a more frequent indication for endoscopy in non-Hispanic whites with erosive esophagitis than in African Americans (28.1% vs 7.9%; P < 0.001). CONCLUSION: Distribution of RE grade and frequency of reflux-related esophageal ulcer, stricture andhiatal hernia are similar in non-Hispanic whites and African Americans. Heartburn was more frequently and nausea/vomiting less frequently reported as the primary endoscopic indication in non-Hispanic whites compared with African Americans with erosive esophagitis or its complications. African Americans have a decreased prevalence of Barrett's esophagus compared with non-Hispanic whites.

关键词： Reflux esophagitis African American Hiatal hernia Barrett's esophagus

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Intestinal stem cells and the colorectal cancer microenvironment

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World journal of Gastroenterology 2014年第8期20卷 1898-1909页

作者： Bryan A Ong kenneth j Vega Courtney W Houchen Department of Digestive Diseases University of Oklahoma Health Sciences CenterOklahoma CityOK 73104United States

Colorectal cancer (CRC) remains a highly fatal condition in part due to its resilience to treatment and its propensity to spread beyond the site of primary occurrence. One possible avenue for cancer to escape eradication is via stem-like cancer cells that, through phenotypic heterogeneity, are more resilient than other tumor constituents and are key contributors to cancer growth and metastasis. These proliferative tumor cells are theorized to possess many properties akin to normal intestinal stem cells. Not only do these CRC “stem” cells demonstrate similar restorative ability, they also share many cell pathways and surface markers in common, as well as respond to the same key niche stimuli. With the improvement of techniques for epithelial stem cell identification, our understanding of CRC behavior is also evolving. Emerging evidence about cellular plasticity and epithelial mesenchymal transition are shedding light onto metastatic CRC processes and are also challenging fundamental concepts about unidirectional epithelial proliferation. This review aims to reappraise evidence supporting the existence and behavior of CRC stem cells, their relationship to normal stem cells, and their possible dependence on the stem cell niche.

关键词： Colon cancer stem cells DCLK1 protein Stem cell niche Cell dedifferentiation

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