Short-term variations in response distribution to cortical stimulation

Lesser, Ronald P.,Lee, Hyang Woon,Webber, W. R. S.,Prince, Barry,Crone, Nathan E.,Miglioretti, Diana L. Oxford University Press 2008 Brain Vol.131 No.6

<P>Patterns of responses in the cerebral cortex can vary, and are influenced by pre-existing cortical function, but it is not known how rapidly these variations can occur in humans. We investigated how rapidly response patterns to electrical stimulation can vary in intact human brain. We also investigated whether the type of functional change occurring at a given location with stimulation would help predict the distribution of responses elsewhere over the cortex to stimulation at that given location. We did this by studying cortical afterdischarges following electrical stimulation of the cortex in awake humans undergoing evaluations for brain surgery. Response occurrence and location could change within seconds, both nearby to and distant from stimulation sites. Responses might occur at a given location during one trial but not the next. They could occur at electrodes adjacent or not adjacent to those directly stimulated or to other electrodes showing afterdischarges. The likelihood of an afterdischarge at an individual site after stimulation was predicted by spontaneous electroencephalographic activity at that specific site just prior to stimulation, but not by overall cortical activity. When stimulation at a site interrupted motor, sensory or language function, afterdischarges were more likely to occur at other sites where stimulation interrupted similar functions. These results show that widespread dynamic changes in cortical responses can occur in intact cortex within short periods of time, and that the distribution of these responses depends on local brain states and functional brain architecture at the time of stimulation. Similar rapid variations may occur during normal intracortical communication and may underlie changes in the cortical organization of function. Possibly these variations, and the occurrence and distribution of responses to cortical stimulation, could be predicted. If so, interventions such as stimulation might be used to alter spread of epileptogenic activity, accelerate learning or enhance cortical reorganization after brain injury.</P>

Communities of Practice, Social Capital and Organizational Knowledge

Lesser, Eric,Prusak, Larry The Korea Society of Management Information System 1999 Information systems review Vol.1 No.1

Communities of Practice, Social Capital and Organizational Knowledge

Eric Lesser,Larry Prusak 한국경영정보학회 1999 Information systems review Vol.1 No.1

The Challenges and Benefits of Bilingualism, Coupled with the Right to Exist in Taiwan Amongst the Aboriginal Community

Michael Lesser 부산외국어대학교 외국어연구소 2018 외국어연구 Vol.31 No.-

This paper will describe the challenges and benefits of being bilingual, from a Taiwanese Siraya aboriginal tribal point of view. Aspects of their language, culture and history will be examined. The Siraya language, Sinckan (also spelt as Sinkang or Sinkan) is going to be the focus of this paper, which will argue the challenges and benefits of being bilingual. Several online sources, books, videos, and personal communications between highly influential people in the Siraya community are the sources that assisted in the creation of this paper. Key words: bilingual, Taiwanese Siraya aboriginal tribal, Sinckan

Buccal gland within the bucinator muscle

Emma R. Lesser,Arada Chaiyamoon,R. Shane Tubbs,Joe Iwanaga 대한해부학회 2024 Anatomy & Cell Biology Vol.57 No.1

There are major and minor salivary glands that aid in the digestive process. Major glands are discrete and exist in predictable locations; minor salivary glands are more widespread and usually found dispersed in the mucosa of the mouth. Glands have their own contractile abilities, which allow them to secrete products without the assistance of vasculature or skeletal, or smooth muscle. This study will describe a cadaveric histological specimen in which an ectopic buccal gland was embedded within bucinator muscle fibers. Potential causes and explanations for this finding will be discussed, as well.

Injective optimal realizations of finite metric spaces

Koolen, J.H.,Lesser, A.,Moulton, V.,Wu, T. North-Holland Pub. Co ; Elsevier Science Ltd 2012 Discrete mathematics Vol.312 No.10

A realization of a finite metric space (X,d) is a weighted graph (G,w) whose vertex set contains X such that the distances between the elements of X in G correspond to those given by d. Such a realization is called optimal if it has minimal total edge weight. Optimal realizations have applications in fields such as phylogenetics, psychology, compression software and internet tomography. Given an optimal realization (G,w) of (X,d), there always exist certain ''proper'' maps from the vertex set of G into the so-called tight span of d. In [A. Dress, Trees, tight extensions of metric spaces, and the cohomological dimension of certain groups: a note on combinatorial properties of metric spaces, Adv. Math. 53 (1984) 321-402], Dress conjectured that any such map must be injective. Although this conjecture was recently disproven, in this paper we show that it is possible to characterize those optimal realizations (G,w) for which certain generalizations of proper maps-that map the geometric realization of (G,w) into the tight span instead of its vertex set-must always be injective. We also prove that these ''injective'' optimal realizations always exist, and show how they may be constructed from non-injective ones. Ultimately it is hoped that these results will contribute towards developing new ways to compute optimal realizations from tight spans.

Prolonged Regression of Metastatic Leptomeningeal Breast Cancer That Has Failed Conventional Therapy: A Case Report and Review of the Literature

Andrew Vincent,Glenn Lesser,Doris Brown,Tamara Vern-Gross,Linda Metheny-Barlow,Julia Lawrence,Michael Chan 한국유방암학회 2013 Journal of breast cancer Vol.16 No.1

Approximately 5% of breast cancer patients develop leptomeningeal metastases over the course of their disease. Though several treatments options are available for these patients, their prognosis is typically considered to be poor. We report a case of leptomeningeal failure after a patient underwent prior radiotherapy, radiosurgery, surgery, chemotherapy, and biologic therapy. This patient experienced a prolonged response after receiving bevacizumab and capecitabine. The literature currently contains several reports regarding the use of systemic therapy to manage leptomeningeal metastases from breast cancer, which we summarize. Finally, we review the relevant effects of the patient’s treatment modalities and provide a rationale for the mechanism that led to her prolonged response.

Effects of solar ultraviolet radiation on coral reef organisms

Banaszak, Anastazia T.,Lesser, Michael P. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.9

Organisms living in shallow-water tropical coral reef environments are exposed to high UVR irradiances due to the low solar zenith angles (the angle of the sun from the vertical), the natural thinness of the ozone layer over tropical latitudes, and the high transparency of the water column. The hypothesis that solar ultraviolet radiation (UVR, 290-400 nm) is an important factor that affects the biology and ecology of coral reef organisms dates only to about 1980. It has been previously suggested that increased levels of biologically effective ultraviolet B radiation (UVB, 290-320 nm), which is the waveband primarily affected by ozone depletion, would have relatively small effects on corals and coral reefs and that these effects might be observed as changes in the minimum depths of occurrence of important reef taxa such as corals. This conclusion was based on predictions of increases in UVR as well as its attenuation with depth using the available data on UVR irradiances, ozone levels, and optical properties of the water overlying coral reefs. Here, we review the experimental evidence demonstrating the direct and indirect effects of UVR, both UVB and ultraviolet A (UVA, 320-400 nm) on corals and other reef associated biota, with emphasis on those studies conducted since 1996. Additionally, we re-examine the predictions made in 1996 for the increase in UVB on reefs with currently available data, assess whether those predictions were reasonable, and look at what changes might occur on coral reefs in the future as the multiple effects (i.e. increased temperature, hypercapnia, and ocean acidification) of global climate change continue.

Utility of 24-hour ambulatory blood pressure monitoring in potential living kidney donors

Aslam Nabeel,Memon Sobia H.,Wadei Hani,Lesser Elizabeth R.,Niazi Shehzad K. 대한고혈압학회 2021 Clinical Hypertension Vol.27 No.4

Introduction: Hypertension (HTN) is a risk factor for cardiovascular disease; therefore, it is imperative to risk stratify potential kidney donors during evaluation. Clinic blood pressure (CBP) measurement is inaccurate in assessing presence or absence of HTN. There is paucity of data about utility of 24-h ambulatory blood pressure monitoring (ABPM) during kidney donor evaluation. Methods: 24-h ABPM is performed on all kidney donors at Mayo Clinic Florida. We conducted retrospective review of 264 consecutive potential kidney donors from 1/1/2012 to 12/31/2017. Demographic, comorbid conditions, laboratory results and 24-h ABPM data were collected. Subjects were divided into two groups: Group1: Subjects with no prior history of HTN and new diagnosis of HTN using 24-h ABPM; Group 2: Subjects with no prior history of hypertension and normal BP on 24-h ABPM. Results: Baseline demographic included mean age 46.40 years, 39% males, 78.4% Caucasians, and mean BMI was 26.94. Twenty one subjects (8.0%) had prior diagnosis of HTN. Among 243 subjects without prior HTN, 62 (25.5%) were newly diagnosed with HTN using 24-h ABPM. CBP was high only in 27 out of 62 (43.6%) of newly diagnosed HTN subjects. Thirty-five subjects (14.4%) had masked HTN and 14 subjects (5.8%) had white-coat HTN. Newly diagnosed hypertensive subjects were more likely to be males as compared to Group 2 (53.2% vs 34.3% P = 0.008). There was a trend of more non-Caucasians subjects (30.6% vs 19.9% P = 0.08) and more active smokers (17.7% vs 11.6%, P = 0.054) in Group1 as compared to Group 2. Only 17 (27.4%) out of 62 newly diagnosed hypertensive subjects were deemed suitable for kidney donation as compared to 105 (58.0%) out of 181 normotensive subjects (P < 0.001). Conclusion: In our cohort, use of ABPM resulted in new diagnosis of HTN in 1 out of 4 potential kidney donors. Newly diagnosed HTN was more common in men, those with non-Caucasian race, and in active smokers. There was a significantly reduced acceptance rate for kidney donation among newly diagnosed HTN subjects. Further studies are needed to determine the value of 24-h ABPM among these high risk groups.

Prospective F-18 FDOPA PET Imaging Study in Human PD

Vijay Dhawan,Martin H Niethammer,Martin L Lesser,Karalyn N Pappas,Matthew Hellman,Toni M Fitzpatrick,David Bjelke,Jaskirat Singh,Loreta M Quatarolo,Yoon Young Choi,Alice Oh,David Eidelberg,Thomas Chal 대한핵의학회 2022 핵의학 분자영상 Vol.56 No.3

Purpose We present the findings of our final prospective study submitted to the U.S. Food and Drug Administration (FDA) for New Drug Application (NDA) approval for the use of 3,4-dihydroxy-6-[18F]fluoro-L-phenylalanine (F-18 FDOPA) positron emission tomography (PET) imaging for Parkinson’s disease (PD). The primary aim was to determine the sensitivity, specificity, and predictive values of F-18 FDOPA PET in parkinsonian patients with respect to clinical standard-oftruth (SOT). Secondary outcomes included the inter-rater reliability, and correlation of quantitative measures for PET with dopaminergic status. Methods In 68 parkinsonian subjects, F-18 FDOPA PET scan from 80 to 100 min was acquired following a CT scan. Scan images were presented to one expert in F-18 FDOPA image interpretation and two physicians with prior experience in I-123 FPCIT single-photon emission computed tomography image interpretation. Fifty-six subjects completed the study with a followup for SOT determination. Image readers were blind to the clinical/quantitative data; SOT clinician was blind to the image data. Results For 47 of the 56 patients, SOT was in agreement with the PET scan results. For nine patients, SOT suggested dopaminergic deficit, whereas the imaging showed normal uptake. The specificity and positive predictive values are 91% and 92%, respectively, suggesting high probability that those who test positive by the PET scan truly have dopaminergic degeneration. The sensitivity was 73%. Inter-rater agreement was 0.6–0.8 between the different readers. Conclusion Our prospective study demonstrates high specificity and moderate sensitivity of F-18 FDOPA PET for PD. We received NDA approval in October 2019.