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Hourlier-Fargette A, Schon S, Xue Y, Avila R, Li W, Gao Y, Liu C, Kim SB, Raj MS, Fields KB, Parsons BV, Lee K, Lee JY, Chung HU, Lee SP, Johnson M, Bandodkar AJ, Gutruf P, Model JB, Aranyosi AJ, Choi J, Ray TR, Ghaffari R, Huang Y, Rogers JA. Skin-interfaced soft microfluidic systems with modular and reusable electronics for in situ capacitive sensing of sweat loss, rate and conductivity. Lab Chip 2020; 20:4391-4403. [PMID: 33089837 PMCID: PMC10556535 DOI: 10.1039/d0lc00705f] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Important insights into human health can be obtained through the non-invasive collection and detailed analysis of sweat, a biofluid that contains a wide range of essential biomarkers. Skin-interfaced microfluidic platforms, characterized by soft materials and thin geometries, offer a collection of capabilities for in situ capture, storage, and analysis of sweat and its constituents. In ambulatory uses cases, the ability to provide real-time feedback on sweat loss, rate and content, without visual inspection of the device, can be important. This paper introduces a low-profile skin-interfaced system that couples disposable microfluidic sampling devices with reusable 'stick-on' electrodes and wireless readout electronics that remain isolated from the sweat. An ultra-thin capping layer on the microfluidic platform permits high-sensitivity, contactless capacitive measurements of both sweat loss and sweat conductivity. This architecture avoids the potential for corrosion of the sensing components and eliminates the need for cleaning/sterilizing the electronics, thereby resulting in a cost-effective platform that is simple to use. Optimized electrode designs follow from a combination of extensive benchtop testing, analytical calculations and FEA simulations for two sensing configurations: (1) sweat rate and loss, and (2) sweat conductivity, which contains information about electrolyte content. Both configurations couple to a flexible, wireless electronics platform that digitizes and transmits information to Bluetooth-enabled devices. On-body field testing during physical exercise validates the performance of the system in scenarios of practical relevance to human health and performance.
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Kim SB, Lee K, Raj MS, Lee B, Reeder JT, Koo J, Hourlier-Fargette A, Bandodkar AJ, Won SM, Sekine Y, Choi J, Zhang Y, Yoon J, Kim BH, Yun Y, Lee S, Shin J, Kim J, Ghaffari R, Rogers JA. Soft, Skin-Interfaced Microfluidic Systems with Wireless, Battery-Free Electronics for Digital, Real-Time Tracking of Sweat Loss and Electrolyte Composition. Small 2018; 14:e1802876. [PMID: 30300469 DOI: 10.1002/smll.201802876] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/12/2018] [Indexed: 05/14/2023]
Abstract
Sweat excretion is a dynamic physiological process that varies with body position, activity level, environmental factors, and health status. Conventional means for measuring the properties of sweat yield accurate results but their requirements for sampling and analytics do not allow for use in the field. Emerging wearable devices offer significant advantages over existing approaches, but each has significant drawbacks associated with bulk and weight, inability to quantify volumetric sweat rate and loss, robustness, and/or inadequate accuracy in biochemical analysis. This paper presents a thin, miniaturized, skin-interfaced microfluidic technology that includes a reusable, battery-free electronics module for measuring sweat conductivity and rate in real-time using wireless power from and data communication to electronic devices with capabilities in near field communications (NFC), including most smartphones. The platform exploits ultrathin electrodes integrated within a collection of microchannels as interfaces to circuits that leverage NFC protocols. The resulting capabilities are complementary to those of previously reported colorimetric strategies. Systematic studies of these combined microfluidic/electronic systems, accurate correlations of measurements performed with them to those of laboratory standard instrumentation, and field tests on human subjects exercising and at rest establish the key operational features and their utility in sweat analytics.
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Affiliation(s)
- Sung Bong Kim
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - KunHyuck Lee
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Milan S Raj
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
| | - Boram Lee
- Department of Medicine, Konkuk University, Seoul, 05029, South Korea
| | - Jonathan T Reeder
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Jahyun Koo
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Aurélie Hourlier-Fargette
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Amay J Bandodkar
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Sang Min Won
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yurina Sekine
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
| | - Jungil Choi
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Yi Zhang
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Medicine, Konkuk University, Seoul, 05029, South Korea
| | - Jangryeol Yoon
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Bong Hoon Kim
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
| | - Yeojeong Yun
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Seojin Lee
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Biomedical, Biological, and Chemical Engineering, University of Missouri, Columbia, MO, 65211, USA
| | - Jiho Shin
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jeonghyun Kim
- Department of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Roozbeh Ghaffari
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Electronics Convergence Engineering, Kwangwoon University, Seoul, 01897, Republic of Korea
| | - John A Rogers
- Center for Bio-Integrated Electronics at the Simpson, Querrey Institute for BioNanotechnology, Northwestern University, Evanston, IL, 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Electronics Convergence Engineering, Kwangwoon University, Seoul, 01897, Republic of Korea
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
- Department of Chemistry, Northwestern University, Evanston, IL, 60208, USA
- Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL, 60208, USA
- Department of Neurological Surgery, Northwestern University, Evanston, IL, 60208, USA
- Simpson Querrey Institute for Nano/Biotechnology, McCormick School of Engineering and Feinberg, School of Medicine, Northwestern University, Evanston, IL, 60208, USA
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Ma Y, Choi J, Hourlier-Fargette A, Xue Y, Chung HU, Lee JY, Wang X, Xie Z, Kang D, Wang H, Han S, Kang SK, Kang Y, Yu X, Slepian MJ, Raj MS, Model JB, Feng X, Ghaffari R, Rogers JA, Huang Y. Relation between blood pressure and pulse wave velocity for human arteries. Proc Natl Acad Sci U S A 2018; 115:11144-11149. [PMID: 30322935 PMCID: PMC6217416 DOI: 10.1073/pnas.1814392115] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Continuous monitoring of blood pressure, an essential measure of health status, typically requires complex, costly, and invasive techniques that can expose patients to risks of complications. Continuous, cuffless, and noninvasive blood pressure monitoring methods that correlate measured pulse wave velocity (PWV) to the blood pressure via the Moens-Korteweg (MK) and Hughes Equations, offer promising alternatives. The MK Equation, however, involves two assumptions that do not hold for human arteries, and the Hughes Equation is empirical, without any theoretical basis. The results presented here establish a relation between the blood pressure P and PWV that does not rely on the Hughes Equation nor on the assumptions used in the MK Equation. This relation degenerates to the MK Equation under extremely low blood pressures, and it accurately captures the results of in vitro experiments using artificial blood vessels at comparatively high pressures. For human arteries, which are well characterized by the Fung hyperelastic model, a simple formula between P and PWV is established within the range of human blood pressures. This formula is validated by literature data as well as by experiments on human subjects, with applicability in the determination of blood pressure from PWV in continuous, cuffless, and noninvasive blood pressure monitoring systems.
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Affiliation(s)
- Yinji Ma
- Department of Engineering Mechanics, Tsinghua University, 100084 Beijing, China
- Center for Flexible Electronics Technology, Tsinghua University, 100084 Beijing, China
| | - Jungil Choi
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Simpson Querrey Institute for Bio-Nanotechnology, Northwestern University, Evanston, IL 60208
| | - Aurélie Hourlier-Fargette
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Simpson Querrey Institute for Bio-Nanotechnology, Northwestern University, Evanston, IL 60208
| | - Yeguang Xue
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208
| | - Ha Uk Chung
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Simpson Querrey Institute for Bio-Nanotechnology, Northwestern University, Evanston, IL 60208
| | - Jong Yoon Lee
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Simpson Querrey Institute for Bio-Nanotechnology, Northwestern University, Evanston, IL 60208
| | - Xiufeng Wang
- School of Materials Science and Engineering, Xiangtan University, 411105 Hunan, China
| | - Zhaoqian Xie
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208
| | - Daeshik Kang
- Department of Mechanical Engineering, Ajou University, 16499 Suwon-si, Republic of Korea
| | - Heling Wang
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208
| | - Seungyong Han
- Department of Mechanical Engineering, Ajou University, 16499 Suwon-si, Republic of Korea
| | - Seung-Kyun Kang
- Department of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology, 34141 Daejeon, Republic of Korea
| | - Yisak Kang
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Xinge Yu
- Department of Biomedical Engineering, City University of Hong Kong, 999077 Hong Kong, China
| | - Marvin J Slepian
- Department of Medicine and Biomedical Engineering, Sarver Heart Center, University of Arizona, Tucson, AZ 85724
| | - Milan S Raj
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
| | - Jeffrey B Model
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
| | - Xue Feng
- Department of Engineering Mechanics, Tsinghua University, 100084 Beijing, China
- Center for Flexible Electronics Technology, Tsinghua University, 100084 Beijing, China
| | - Roozbeh Ghaffari
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Simpson Querrey Institute for Bio-Nanotechnology, Northwestern University, Evanston, IL 60208
- Department of Chemistry and Biomedical Engineering, Northwestern University, Evanston, IL 60208
| | - John A Rogers
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208;
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Simpson Querrey Institute for Bio-Nanotechnology, Northwestern University, Evanston, IL 60208
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208
- Department of Chemistry and Biomedical Engineering, Northwestern University, Evanston, IL 60208
- Department of Dermatology, Northwestern University, Evanston, IL 60208
- Feinberg School of Medicine Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208
- Department of Neurological Surgery, Northwestern University, Evanston, IL 60208
- Department of Chemistry, Northwestern University, Evanston, IL 60208
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
- Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Yonggang Huang
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208;
- Center for Bio-Integrated Electronics, Northwestern University, Evanston, IL 60208
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208
- Department of Mechanical Engineering, Northwestern University, Evanston, IL 60208
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Liu Y, Tian L, Raj MS, Cotton M, Ma Y, Ma S, McGrane B, Pendharkar AV, Dahaleh N, Olson L, Luan H, Block O, Suleski B, Zhou Y, Jayaraman C, Koski T, Aranyosi AJ, Wright JA, Jayaraman A, Huang Y, Ghaffari R, Kliot M, Rogers JA. Intraoperative monitoring of neuromuscular function with soft, skin-mounted wireless devices. NPJ Digit Med 2018; 1. [PMID: 30882044 PMCID: PMC6419749 DOI: 10.1038/s41746-018-0023-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Peripheral nerves are often vulnerable to damage during surgeries, with risks of significant pain, loss of motor function, and reduced quality of life for the patient. Intraoperative methods for monitoring nerve activity are effective, but conventional systems rely on bench-top data acquisition tools with hard–wired connections to electrode leads that must be placed percutaneously inside target muscle tissue. These approaches are time and skill intensive and therefore costly to an extent that precludes their use in many important scenarios. Here we report a soft, skin-mounted monitoring system that measures, stores, and wirelessly transmits electrical signals and physical movement associated with muscle activity, continuously and in real-time during neurosurgical procedures on the peripheral, spinal, and cranial nerves. Surface electromyography and motion measurements can be performed non-invasively in this manner on nearly any muscle location, thereby offering many important advantages in usability and cost, with signal fidelity that matches that of the current clinical standard of care for decision making. These results could significantly improve accessibility of intraoperative monitoring across a broad range of neurosurgical procedures, with associated enhancements in patient outcomes. A small skin-mounted biosensing device accurately and non-invasively monitors neuromuscular activity in real-time during surgery. With many surgical procedures there is a risk of nerve damage. Although this is often temporary, in some cases it can significantly affect patients’ quality of life. Existing monitoring systems that rely on the accurate placement of needle electrodes into target nerves are cumbersome and expensive. The device developed by a team led by John Rogers, at Northwestern University, and Michel Kliot, at Stanford University, can easily be accommodated to any part of the body to monitor muscle activity in response to nerve impulses and stimulation during surgery. Furthermore, it can wirelessly transmit signals of comparable quality to needle-based systems. These devices could not only increase the use of intraoperative monitoring in hospitals but also contribute to make surgery safer.
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Affiliation(s)
- Yuhao Liu
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Limei Tian
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | - Matthew Cotton
- Department of Neurosurgery, Northwestern Memorial Hospital, Chicago, IL 60611, USA
| | - Yinji Ma
- Department of Engineering Mechanics, AML, Center for Mechanics and Materials, Tsinghua University, 100084 Beijing, China.,Department of Civil and Environmental Engineering, Mechanical Engineering, and Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Siyi Ma
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | - Arjun V Pendharkar
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Nader Dahaleh
- Department of Neurosurgery, Northwestern Memorial Hospital, Chicago, IL 60611, USA
| | | | - Haiwen Luan
- Department of Civil and Environmental Engineering, Mechanical Engineering, and Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Orin Block
- Department of Neurosurgery, Northwestern Memorial Hospital, Chicago, IL 60611, USA
| | | | - Yadong Zhou
- Department of Civil and Environmental Engineering, Mechanical Engineering, and Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.,Department of Engineering Mechanics, Southeast University, 210096 Nanjing, China
| | - Chandrasekaran Jayaraman
- Max Nader Lab for Rehabilitation Technologies and Outcomes Research, Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA.,Departments of Physical Medicine & Rehabilitation and Medical Social Sciences, Northwestern University, Chicago, IL, USA
| | - Tyler Koski
- Department of Neurosurgery, Northwestern Memorial Hospital, Chicago, IL 60611, USA
| | | | | | - Arun Jayaraman
- Max Nader Lab for Rehabilitation Technologies and Outcomes Research, Center for Bionic Medicine, Rehabilitation Institute of Chicago, Chicago, IL 60611, USA.,Departments of Physical Medicine & Rehabilitation and Medical Social Sciences, Northwestern University, Chicago, IL, USA
| | - Yonggang Huang
- Department of Civil and Environmental Engineering, Mechanical Engineering, and Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.,Center for Bio-Integrated Electronics, Departments of Materials Science and Engineering, Biomedical Engineering, Chemistry, Mechanical Engineering, Electrical Engineering and Computer Science, Neurological Surgery, Simpson Querrey Institute for Nano/Biotechnology, McCormick School of Engineering, Feinberg School of Medicine, Northwestern University, Evanston, IL 60208, USA
| | - Roozbeh Ghaffari
- MC10 Inc., Lexington, MA 02421, USA.,Center for Bio-Integrated Electronics, Departments of Materials Science and Engineering, Biomedical Engineering, Chemistry, Mechanical Engineering, Electrical Engineering and Computer Science, Neurological Surgery, Simpson Querrey Institute for Nano/Biotechnology, McCormick School of Engineering, Feinberg School of Medicine, Northwestern University, Evanston, IL 60208, USA
| | - Michel Kliot
- Department of Neurosurgery, Northwestern Memorial Hospital, Chicago, IL 60611, USA.,Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - John A Rogers
- Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.,Center for Bio-Integrated Electronics, Departments of Materials Science and Engineering, Biomedical Engineering, Chemistry, Mechanical Engineering, Electrical Engineering and Computer Science, Neurological Surgery, Simpson Querrey Institute for Nano/Biotechnology, McCormick School of Engineering, Feinberg School of Medicine, Northwestern University, Evanston, IL 60208, USA
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Rahmathullah L, Raj MS, Chandravathi TS. Aetiology of severe vitamin A deficiency in children. Natl Med J India 1997; 10:62-5. [PMID: 9153981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Severe forms of vitamin A deficiency or keratomalacia are common in young children. Keratomalacia is thought to be associated with malnutrition due to poor weaning practices and manifests at 3 to 4 years of age. As survival rates for infants have increased, keratomalacia is being seen in children less than 6 months of age. Hence, keratomalacia shows two peaks--one in early infancy and the other in the toddler or pre-school age groups. However, the reasons for its occurrence at these ages may be different. METHODS Records of children admitted to the Nutrition Rehabilitation Centre at the Government Rajaji Hospital during 1971-89 and at the Aravind Children's Hospital during 1991-93 were reviewed for severity of vitamin A deficiency associated with protein-energy malnutrition. Records of 1990 were not available. RESULTS During 1971-89, 4691 children were admitted to the Nutrition Rehabilitation Centre for Nutritional rehabilitation and treatment of vitamin A deficiency. Of these, 1575 (33.6%) children had corneal involvement due to vitamin A deficiency. During 1991-93, 7439 children in the age group of 0-15 years were seen at the Aravind Children's Hospital--185 had vitamin A deficiency; 133 were below the age of 5 years and 69 had keratomalacia. Fifteen children with keratomalacia were below the age of one year and 12 were below 6 months of age. CONCLUSION The incidence of severe vitamin A deficiency of keratomalacia shows two peaks; one in early infancy (< 6 months) and the other in the pre-school age group. The first peak is probably related to maternal nutrition and decreased breast-feeding while the second peak is possibly related to poor weaning practices.
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Abstract
Three cases of monomorphic basal cell adenoma of the parotid glands were studied with light microscopy. In one patient, fresh tissue was available for electron microscopic observations. On the basis of ultrastructural findings it was concluded that myoepithelial cells play little, if any, role in the histogenesis of this lesion. The tumor originates from the undifferentiated stem cells analogous to the cells seen at the "end bud" stage of salivary gland morphogenesis prior to their further cytodifferentiation and functional maturation into secretory and myoepithelial cells. In fully developed salivary glands such undifferentiated stem cells reside as "reserve" cells in the intercalated ductal system.
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Abstract
A detailed electronmicroscopic study on glycogen-rich tumor is presented. The neoplasm originated from the minor salivary glands on the ventral surface of the tongue. The role of myoepithelial cells in the histogenesis of this lesion is not supported. It is proposed that the tumor arises from "undifferentiated" stem cells analogous to cells in the "end bud" stage of salivary gland morphogenesis. The presence of a large amount of glycogen is secondary to defective carbohydrate metabolism within the tumor cells.
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8
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Chaudhry AP, Cutler LS, Montes M, Satchidanand S, Raj MS. Electron microscopy; its application in diagnostic pathology. N Y State J Med 1980; 80:1809-1814. [PMID: 6262688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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