Gopinathan Menon

Gopinathan Menon
California Academy of Sciences · Ornithology & Mammology

MS; PhD

About

139
Publications
14,306
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
8,483
Citations
Citations since 2017
12 Research Items
1524 Citations
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
2017201820192020202120222023050100150200250
Introduction
Gopinathan Menon is currently a research Associate at the Ornithology & Mammology, California Academy of Sciences, and is a Fellow of the Academy. Gopinathan does research in Anatomy, Cell Biology and Molecular Biology of vertebrate epidermis. Current projects include '"comparative studies on Vertebrate skin barrier ; an overview of Cetacean skin adaptations as well as " Specialization of the Avian integument". He also maintains an interest in Cosmetic science, as it relates to ageing and related changes in structure and functions of human skin .
Additional affiliations
October 2007 - January 2017
ISP/Ashland Inc.
Position
  • Senior Researcher
Description
  • Research on Innovation and discovery of personal care active ingredients
January 1993 - October 2007
Avon Products, Inc
Position
  • Principal Research Fellow
October 1991 - December 2013
California Academy of Sciences
Position
  • Fellow
Description
  • I have a life long affiliation with Cal Academy owing to my being elected as a Fellow of the Academy .I still have collaborative research projects there.

Publications

Publications (139)
Article
Full-text available
Cetacean skin continues to be the investigative focus of researchers from several different scientific disciplines. Yet, most research on the basic functions of lipo‐keratinocytes, which constitute most of the cetacean epidermis, providing the first layer of protection against various environmental aggressors (including an ever‐increasing level of...
Article
The stratum corneum (SC), the top layer of the epidermis, is the functional site of the skin barrier and serves to maintain hydration of the body by preventing water loss and thwarting the entrance of pathogens. The naked mole rat (NMR) (Heterocephalus glaber) is a rodent that resides in hypoxic underground tunnels in arid Africa. NMRs are not only...
Article
We describe and interpret the functional morphology of skin of the Yellow‐bellied sea snake, Hydrophis platurus. This is the only pelagic sea snake, and its integument differs from what is known for other species of snakes. In gross appearance, the scales of H. platurus consist of non‐overlapping, polygonal knobs with flattened outer surfaces beari...
Article
Full-text available
The corneocyte lipid envelope (CLE), a monolayer of ω-hydroxyceramides whose function(s) remain(s) uncertain, is absent in patients with autosomal recessive congenital ichthyoses with mutations in enzymes that regulate epidermal lipid synthesis. Secreted lipids fail to transform into lamellar membranes in certain autosomal recessive congenital icht...
Article
The epidermal lamellar bodies (LBs) are specialized organelles that contain pro-barrier lipids imparting a fully lamellar internal structure, but also other cargoes such as enzymes (lipid metabolizing and proteolytic), enzyme inhibitors, and antimicrobial peptides. Thus, the LB secretory system, by virtue of delivering these cargoes to the stratum...
Article
Full-text available
The significance of Coenzyme Q10 (CoQ10) as an anti-oxidant barrier of the skin, as well as a key component in anti-aging strategies for skin care products, has been firmly established. Biosynthesis of CoQ10 in the mitochondria is well known, but there is only limited information on the non-mitochondrial synthesis of CoQ10 in the skin. Recent findi...
Poster
Full-text available
Skin tone is a subject of constant interest and research in the personal care industry. A plant fraction (lotus serum fraction, also known as Nelumbo nucifera extract) was sustainably obtained by applying Ashland’s novel Zeta Fraction technology to living Sacred Lotus plants and subsequently evaluated in two relevant model systems (mouse melanoma c...
Article
In a paper published at the J Invest Dermatol in 1998 Nik Kollias and coworkers described distinct changes in skin native fluorescence associated with skin aging and photoaging, using in vivo fluorescence excitation spectroscopy. The assignment of the 295 nm band to tryptophan fluorescence had a profound significance influencing many later studies...
Article
Full-text available
The personal care industry has unmet needs for effective and safe cosmetic ingredients that are derived from natural sources and capable of improving skin tone. Development of skin tone is a complex process which includes melanogenesis, melanosome transfer, and distribution of melanin within keratinocytes. The ability of lotus serum fraction, a nov...
Article
Full-text available
Here we report three patients with severe palmoplantar keratoderma associated with ichthyosis and sensorineural deafness. Bi-allelic mutations were found in VPS33B, encoding VPS33B, a Sec1/Munc18 family protein which interacts with Rab11a and Rab25 proteins and is involved in trafficking of the collagen modifying enzyme LH3. Two patients were homoz...
Article
Full-text available
The personal care industry has unmet needs for effective and safe cosmetic ingredients that are derived from natural sources and capable of improving skin tone. Development of skin tone is a complex process which includes melanogenesis, melanosome transfer, and distribution of melanin within keratinocytes. The ability of lotus serum fraction, a no...
Article
Calcium and 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) are promoters of epithelial cell functions; however their effects on sebaceous glands are unknown. In this study, morphology, ultrastructure, cell numbers, lipid synthesis and apoptosis of SZ95 sebocytes were assessed in vitro under different concentrations of extracellular calcium with or without...
Article
“Cholesterol is good for your skin” may be an improbable headline that you would see in a health magazine—but it is the reality. Cholesterol is required to form membranes in cells and is also crucial for the formation of the extracellular lamellae in the stratum corneum that provides the permeability barrier for the skin. Keratinocytes in the epide...
Article
Skin is the body’s protective barrier against a whole battery of environmental aggressors—both of natural and anthropogenic origins. It primarily protects against desiccation, and thus makes life on land possible. Every class of terrestrial organism has evolved an appropriate barrier against fluid loss from the body and almost all employ modificati...
Conference Paper
Background: Calcium and 1,25-dihydroxyvitamin D3 are well-known promoters of epithelial cell functions; however their effects on the sebaceous gland and its diseases are not clearly elucidated. Objective: The in vitro part of our study was performed in order to evaluate extracellular calcium and 1,25-dihydroxyvitamin D3 effects onhuman sebocytes. I...
Article
Full-text available
Classic Refsum disease (RD) is a rare, autosomal recessively-inherited disorder of peroxisome metabolism due to a defect in the initial step in the alpha oxidation of phytanic acid (PA), a C16 saturated fatty acid with four methyl side groups, which accumulates in plasma and lipid enriched tissues (please see van den Brink and Wanders, Cell Mol Lif...
Article
Birds in the genus Pitohui and Ifrita carry potent neurotoxins that are most abundant in skin and feathers. It was unknown precisely how or where in the skin these chemicals are stored. Here we report high-resolution electron microscopy using OsO4 staining to visualize the location of alkaloids. Our images suggest that toxic alkaloids accumulate in...
Article
Corneocytes in mammalian stratum corneum are surrounded by a monolayer of covalently bound ω-OH-ceramides that form the corneocyte (-bound) lipid envelope (CLE). We review here the structure, composition, and possible functions of this structure, with insights provided by inherited and acquired disorders of lipid metabolism. This article is part of...
Article
Over the past 150 years the skin's structure and function has been the subject of much investigation by scientists. The stratum corneum (SC), the skin's outermost layer and interface with the outside world is now well recognized as the barrier that prevents unwanted materials from entering, and excessive loss of water from exiting the body. This re...
Article
One of the main functions of the skin is to protect the organism against environmental threats, such as thermal stress. Aquaporin-3 (AQP3) facilitates water and glycerol transport across cell membranes and therefore regulates osmotic balance in different situations of stress. This mechanism seems to be particularly important for the resistance of d...
Article
Current explanations for the development of epidermal pigmentation during human evolution are not tenable as stand-alone hypotheses. Accordingly, we assessed instead whether xeric- and UV-B-induced stress to the epidermal permeability barrier, critical to survival in a terrestrial environment, could have "driven" the development of epidermal pigmen...
Article
Mitochondria, long considered to have the primary role in cellular energetic, have been the center of much research interest in the recent past. Technological advances in microscopy and development of new and specific fluorescent dyes for visualization of mitochondrial dynamics in living cells have facilitated the newfound interest in these fascina...
Chapter
So much of basic and applied research has been reported on the skin barrier in the past three decades that it is an uphill task to write something different and new on the topic. Several recent books have described the structural basis of the barrier, biochemical, and molecular aspects of its regulation, and its implications in health and disease (...
Chapter
This chapter focuses mainly on the treatments for face, as facial beauty and appearance are the most significant and recognizable yardstick of youth and aging in human societies. Antiaging cosmetic products are being developed with the most sophisticated cell and molecular biology techniques, including gene arrays, SAGE, and proteomics in scientifi...
Article
Full-text available
Low-frequency sonophoresis (LFS) has been shown to disrupt the structure of stratum corneum (SC) lipid bilayers and enhance SC permeability. In this study, we examined the penetration pathway of lanthanum nitrate (LaNO(3)) tracer in viable epidermis after combined treatment of LFS and tape stripping (TS), as a physical enhancer, or oleic acid (OA)...
Article
The fascinating topic of skin barrier continues to engage researchers from diverse disciplines both in academia and industry. Much of the information on the basic biology of barrier formation, its ontogeny as well as repair and homeostasis comes from studies on animal models. A smaller number of human studies have validated the usefulness of animal...
Article
Full-text available
Evolutionary transitions between different environmental media such as air and water pose special problems with respect to skin permeability because of the dramatic changes in the driving gradients and nature of water exchange processes. Also, during the transitional periods prior to complete adaptation to a new medium, the skin is exposed to two v...
Article
It is widely assumed that the epidermis of early hominids lacked pigmentation, as does the skin of their primate ancestors (Jablonski and Chaplin, 2000; Westerhof, 2007). Several theories have been advanced to explain the subsequent latitude-dependent development and divergence of human pigmentation, including still widely held hypotheses that pigm...
Article
Full-text available
Several bird species in the endemic New Guinean genus Pitohui contain potent defensive toxins of the batrachotoxin family of steroidal alkaloid neurotoxins. We surveyed toxin concentrations in various tissues of Hooded Pitohui (Pitohui dichrous) using radioligand binding assays. The highest concentrations were found in the skin and feathers, on the...
Article
Transepidermal water loss was studied in nestlings, fledglings and adults of the xerophylic Zebra Finch Poephila guttata. Nestlings lose little water (2–4 ppm/0–5 cm2/h) through the skin as compared to adults (60–70 ppm/0–5 cm2/h). Light and electron microscopic examination of the skin sections of both age classes revealed an abundance of lipids in...
Article
The particle-mediated delivery systems are becoming a clinically relevant tool in dermatology and immunology. We investigated the qualitative ultrastructural morphology of skin following pressure-driven delivery of gold particles to ex vivo human breast skin, at different pressures ranging from 350 to 1,000 psi. Pressures of 800 and 1,000 psi appea...
Article
Full-text available
Low-frequency sonophoresis (LFS) has been well documented to enhance the permeability of skin to macromolecular drugs via induction of localized transport regions. However, the organizational details of epidermis, specifically stratum corneum (SC), during sonophoresis are beyond the resolution limit of common histo-optical microscopy tools, which f...
Article
Mutations in the gene for steroid sulfatase (SSase), are responsible for recessive x-linked ichthyosis (RXLI). As a consequence of SSase deficiency, its substrate, cholesterol sulfate (CSO4), accumulates in the epidermis. Accumulation of this amphipathic lipid in the outer epidermis provokes both a typical scaling phenotype and permeability barrier...
Article
Photomechanical waves (high amplitude pressure transients generated by lasers) have been shown to permeabilize the stratum corneum in vivo and facilitate the transport of macromolecules into the viable epidermis. The permeabilization of the stratum corneum is transient and its barrier function recovers. Sites on the volar forearm of humans were exp...
Article
The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
Article
The stratum corneum is a complex tissue that is metabolically active, and undergoes dynamic structural modifications due to the presence of several self-regulating enzymatic systems. A large number of defensive (protective) functions are embodied in this tissue, each with its own structural and biochemical basis. Moreover, the stratum corneum is re...
Article
The formation, structural organization, and barrier functions of stratum corneum (SC) are reviewed. Stratum corneum is considered as a composite material and a biopolymer with properties so unique as to consider it a 'smart material'. SC, together with stratum granulosum (SG) responds (as an actively smart material) to environmental signals with ap...
Article
Full-text available
A competent barrier to transepidermal water loss (TEWL) is essential for terrestrial life. In various vertebrates, epidermal water barriers composed of lipids prevent excessive TEWL, which varies inversely with habitat aridity. Little is known, however, about the mechanisms and regulation of permeability relative to natal transition from the 'aqueo...
Chapter
The traditional view of the stratum corneum (SC) regards the outer layer of the epidermis to be relatively impermeable, highly resilient, and analogous to plastic wrap. This passive model, which holds that permeation is governed solely by the physical-chemical properties of the SC (1), still dominates strategies for transdermal drug delivery. Based...
Article
Background Although occlusive dressings have great potential in the management of psoriasis vulgaris, the therapeutic mechanism is not completely understood. Occlusion artificially restores and corrects the defective barrier in psoriasis plaques. Additionally, occlusion is know to normalize the epidermal calcium gradients in hyperproliferative muri...
Chapter
As the largest organ comprising more than 10% of the body mass in humans, the skin serves as the physical barrier for the body. The bulk of it is made up of dermis, but it is the epidermis that is vested with the function of producing, maintaining and renewing the superficial and crucial compartment, the stratum corneum (SC). This layer of terminal...
Article
Full-text available
SYNOPSIS. The avian epidermis is composed of unique sebokeratinocytes that elaborate and secrete sebum-like lipids as they cornify. In addition to the lipid droplets, the avian epidermis elaborates, but rarely secretes, lipid—enriched or- ganelles, the multigranular bodies. The multigranular bodies are analogous to the lamellar bodies of mammals (M...
Article
Full-text available
The contents of epidermal lamellar bodies (LB) are delivered selectively to the intercellular spaces at the stratum granulosum (SG)-stratum corneum (SC) interface. We assessed the subcellular basis for LB secretion first by confocal microscopy, following labeling with Nile red or NBD-ceramide, which reveals a tubulo-reticular membrane system within...
Article
Full-text available
Alpha-hydroxy acids (AHA) such as glycolic acid have recently been used extensively in cosmetic and dermatological formulas. In low concentration (2-5%) glycolic acid is believed to facilitate progressive weakening of cohesion of the intercellular material of the stratum corneum (SC), resulting in uniform exfoliation of its outermost layers (the st...
Article
An overview of the morphological correlates of mammalian epidermal lipids and the cutaneous permeability barrier is provided. The following features are discussed: 1) ultrastructural characterization of the progressive lipid alterations accompanying normal stratum corneum (SC) formation; 2) effects of drugs/inhibitors that interfere with specific a...
Article
Although prior morphologic studies have shown that both polar and nonpolar materials permeate across the stratum corneum (SC) via a paracellular route, the actual pathway through these heterogeneous domains is unknown. We applied hydrophilic and hydrophobic tracers in vivo to murine skin under basal conditions and/or after permeation enhancement wi...
Article
The ultrastructure of naked neck epidermis from the ostrich (Struthio camelus) and ventral apterium from watered, and water-deprived, Zebra finches (Taeniopygia [Poephila] guttata castanotis) is presented. The form and distribution of the fully differentiated products of the lipid-enriched multigranular bodies are compared in biopsies post-fixed wi...
Article
Dry skin and eczema only seldomly occur in workers in the Danish fish-processing industry (FPI) during work, when their fingers and palms have a low skin surface temperature, low transepidermal water loss (TEWL), and a high capacitance. However, shortly after work, when the skin temperature has become normal, TEWL levels increase to above normal, a...
Article
The epidermal permeability barrier is formed by lipids delivered to the intercellular spaces through the secretion of lamellar bodies. Prior studies have shown that the rate of lamellar body secretion appears to be regulated by the extracellular calcium content of the upper epidermis, which is altered following permeability barrier disruption. To d...
Article
Full-text available
The intercellular spaces of the outermost layers of the epidermis (stratum corneum, SC) of terrestrial mammals contain a mixture of lipids, enriched in ceramides that are critical for the epidermal permeability barrier. Whereas glucosylceramides (GlcCer) are synthesized in abundance in the epidermis, they disappear coincident with an increase of ce...
Article
Full-text available
Hydrolysis of glucosylceramide by beta-glucocerebrosidase results in ceramide, a critical component of the intercellular lamellae that mediate the epidermal permeability barrier. A subset of type 2 Gaucher patients displays ichthyosiform skin abnormalities, as do transgenic Gaucher mice homozygous for a null allele. To investigate the relationship...
Article
Prior studies have demonstrated a Ca2+ gradient within the epidermis, with the highest concentration in the outer nucleated layers, disappearance of the Ca2+ gradient when the permeability barrier is acutely disrupted, and reappearance of the Ca2+ gradient in parallel with barrier repair, and disruption of the gradient in psoriasis. These observati...
Article
The mechanism of stratum corneum (SC) permeabilization by ultrasound (sonophoresis) is unknown. We studied here permeation pathways, and SC intercellular structural organization following applications of high-frequency sonophoresis to hairless mouse skin. Ruthenium tetroxide post-fixation and tracer solutions of LaNO3 and FITC-dextrans were employe...
Article
Full-text available
The cutaneous permeability barrier to systemic water loss is mediated by hydrophobic lipids forming membrane bilayers within the intercellular domains of the stratum corneum (SC). The barrier emerges during day 20 of gestation in the fetal rat and is correlated with increasing SC thickness and increasing SC lipid content, the appearance of well-for...
Article
We examined the possibility that the cutaneous permeability barrier regulates epidermal DNA synthesis in two acute and two chronic models of barrier perturbation. In animals treated topically with acetone, DNA synthesis is increased 102%, in tape-stripped animals 127%, in essential fatty acid deficient animals 50%, and in animals chronically treate...
Article
The epidermal permeability barrier is provided by intercellular lipids forming multiple membrane bilayers in the stratum corneum. In the fetal rat, the barrier to transepidermal water loss forms during the 20th d of gestation and is accompanied by 1) increasing stratum corneum thickness; 2) increasing stratum corneum lipid content, particularly non...
Article
Full-text available
The interstices of the mammalian stratum corneum contain lipids in a system of continuous membrane bilayers critical for the epidermal permeability barrier. During the transition from inner to outer stratum corneum, the content of polar lipids including glucosylceramides, decreases while ceramide content increases. We investigated whether inhibitio...