Gray Hair Research Articles

Hair follicle-targeted delivery for hair recoloration using scalp-curvature-conforming microneedles based on sodium alginate and polyvinylpyrrolidone

Hair-related disorders are currently widely concerned issues for not only the scientific society but also the public attentions. Microneedle-based drug delivery system has been regarded as a promise hair follicle-targeted drug delivery approach, largely because they can effectively penetrate the stratum corneum barrier and deliver drugs to hair follicles within dermis. However, the currently reported microneedles for treating hair-related disorders usually rely on rigid backings, showing poor adaptability to the curved scalp and thereby restricting their usability for hair follicles targeted drug delivery. To this end, this study utilized sodium alginate and polyvinylpyrrolidone to construct a scalp-curvature-conforming microneedle with flexible backing. Subsequently, Psoralea corylifolia extract (PE) was loaded into the microneedles to investigate its capability in delivering PE to the hair follicle site for treating leukotrichia associated with vitiligo. These PE-loaded microneedles can effectively conform to the curvature of skin, enhancing the efficiency of microneedle insertion and ensuring stable drug delivery. Moreover, animal studies demonstrate that the PE loaded microneedles can effectively penetrate the stratum corneum, benefiting the drug delivery to hair follicles located site, and consequently showing a successful inhibition of hair graying. In summary, the present study reports a design and preparation of scalp-curvature-conforming microneedle. This design may offer a potential solution for efficient drug delivery using microneedles to the curved skin.

Transforming stereotypes: how meeting male and female professors changes children's gender bias and ‘mad professor’ perceptions

ABSTRACT The persistent ‘mad professor’ stereotype – the perception of professors as typically old, dishevelled men with grey hair – contributes to the lack of diversity in the academic workforce, with important implications for social justice and the advancement of science. This study examined the research question of how an informal classroom visit by a male versus a female professor influences gender bias and mad professor stereotyping among upper primary school students. To investigate this question, a survey was conducted with 171 upper elementary school children, examining their gender bias and mad professor stereotyping both before and after a classroom visit from either a male or female professor. The results revealed that visits by female professors significantly reduced gender bias, while visits from male professors, conversely, heightened it. However, this bias-reinforcing effect of male visits was mitigated through supplementary activities that introduced the children to professors from diverse genders and backgrounds. Importantly, visits from both male and female professors were effective in diminishing mad professor stereotyping. This study not only highlights the critical role of a professor’s gender in shaping children’s perceptions but also introduces a novel pictorial choice task for measuring bias, offering an objective alternative to the traditional Draw-a-Scientist test.

Dermal Papilla Cells: From Basic Research to Translational Applications.

As an appendage of the skin, hair protects against ultraviolet radiation and mechanical damage and regulates body temperature. It also reflects an individual's health status and serves as an important method of expressing personality. Hair loss and graying are significant psychosocial burdens for many people. Hair is produced from hair follicles, which are exclusively controlled by the dermal papilla (DP) at their base. The dermal papilla cells (DPCs) comprise a cluster of specialized mesenchymal cells that induce the formation of hair follicles during early embryonic development through interaction with epithelial precursor cells. They continue to regulate the growth cycle, color, size, and type of hair after the hair follicle matures by secreting various factors. DPCs possess stem cell characteristics and can be cultured and expanded in vitro. DPCs express numerous stemness-related factors, enabling them to be reprogrammed into induced pluripotent stem cells (iPSCs) using only two, or even one, Yamanaka factor. DPCs are an important source of skin-derived precursors (SKPs). When combined with epithelial stem cells, they can reconstitute skin and hair follicles, participating in the regeneration of the dermis, including the DP and dermal sheath. When implanted between the epidermis and dermis, DPCs can induce the formation of new hair follicles on hairless skin. Subcutaneous injection of DPCs and their exosomes can promote hair growth. This review summarizes the in vivo functions of the DP; highlights the potential of DPCs in cell therapy, particularly for the treatment of hair loss; and discusses the challenges and recent advances in the field, from basic research to translational applications.

Skin senescence-from basic research to clinical practice.

The most recognizable implications of tissue aging manifest themselves on the skin. Skin laxity, roughness, pigmentation disorders, age spots, wrinkles, telangiectasia or hair graying are symptoms of physiological aging. Development of the senescent phenotype depends on the interaction between aging cells and remodeling of the skin's extracellular matrix (ECM) that contains collagen and elastic fiber. Aging changes occur due to the combination of both endogenous (gene mutation, cellular metabolism or hormonal agents) and exogenous factors (ultraviolet light, environmental pollutants, and unsuitable diet). However, overproduction of mitochondrial reactive oxygen species (ROS) is a key factor driving cellular senescence. Aging theories have disclosed a range of diverse molecular mechanisms that are associated with cellular senescence of the body. Theories best supported by evidence include protein glycation, oxidative stress, telomere shortening, cell cycle arrest, and a limited number of cell divisions. Accumulation of the ECM damage is suggested to be a key factor in skin aging. Every cell indicates a functional and morphological change that may be used as a biomarker of senescence. Senescence-associated β-galactosidase (SA-β-gal), cell cycle inhibitors (p16INK4a, p21CIP1, p27, p53), DNA segments with chromatin alterations reinforcing senescence (DNA-SCARS), senescence-associated heterochromatin foci (SAHF), shortening of telomeres or downregulation of lamina B1 constitute just an example of aging biomarkers known so far. Aging may also be assessed non-invasively through measuring the skin fluorescence of advanced glycation end-products (AGEs). This review summarizes the recent knowledge on the pathogenesis and clinical conditions of skin aging as well as biomarkers of skin senescence.

Delving into diversity: Exploring different risk factors of premature greying of hair.

Dear Madam, Hair is said to grey prematurely when a minimum of five grey hairs occur before the age of 20 in Caucasians, 25 in Asians and 30 in Africans1. Some authors propose using 25 years as a cut-off for people in the South Asian subcontinent. Also, there's no universal grading system for premature greying of hair (PGH). This letter addresses the various evolving risk factors for PGH in young adults worldwide. PGH may be familial or genetically influenced, traveling in an Autosomal Dominant pattern. A positive family history, in particular the paternal history is the most powerful risk factor2. PGH is also linked to nutritional deficiencies including vitamins (especially B12) and minerals. For example in one study, significantly lower levels of serum calcium, ferritin, vitamin B12, and high HDL were observed in patients3. T3 and T4 act on hair follicles to cause melanogenesis and their deficiency is therefore associated with PGH, alopecia, and changes in hair morphology. Another study found notably reduced levels of copper in cases (PGH) as compared to the control group. This study, however, did not observe lower levels of zinc or iron among the affected population. A separate case-control study concerning the association of epidemiological and biochemical factors with PGH reported that a significantly higher percentage of individuals with premature greying had atopic diathesis, led sedentary lifestyles, had family histories of the condition, smoked, and had reported higher levels of perceived stress compared to controls. Though, interestingly enough, regular application of hair oil seemed to confer a safeguarding effect against premature greying. Upon further review of the literature, it became apparent that both BMI and exposure to sunlight emerged as substantial predictors of PGH. Despite the prescription of various vitamins and minerals like biotin, calcium pantothenate, zinc, copper, and selenium (all of which have been recognized as risk factors), the outcomes have been disappointing. Calcium pantothenate is frequently recommended for premature greying of hair (PGH)4. This highlights an existing knowledge gap concerning the precise causative risk factors, necessitating further investigation for a comprehensive understanding and improved management of individuals experiencing premature greying of hair.

Prevalence and Predictors of Premature Graying of Hair Before the Age of 30: A Cross-Sectional Study in SaudiArabia.

Graying is an inherent and unavoidable consequence of the aging process, impacting individuals of all genders. There are limited studies in Saudi Arabia that have examined the prevalence and predictors of premature graying of hair (PGH). This study aims to explore the prevalence and predictors of PGH before the age of 30 among the population of Saudi Arabia. This is a cross-sectional online survey that was conducted between July 2023 and February 2024 in Saudi Arabia. Binary logistic regression analysis was used to identify risk factors of having gray hair before the age of 30. A total of 1193 participants were involved in this study. A significant portion of respondents reported having gray hair before the age of 30 (55.9%). The younger population (younger than 44 years), smokers, and those who have comorbidities, have anxiety, have depression, have a family history of gray hair before the age of 30 years, have a dry scalp, suffer from vitamin or mineral deficiencies, have hair loss due to immune diseases (such as alopecia), and use minoxidil or rosemary for hair loss were more likely to have gray hair before the age of 30 years (p < 0.05). This study highlighted the high prevalence rate and associated predictors of PGH in Saudi Arabia. Identified predictors include genetic, health, and lifestyle factors. Healthcare professionals and decision makers are advised to promote the awareness of the general public on its risk factors to enhance the prevention of PGH. Public health initiatives include campaigns on smoking cessation, healthy nutrition, and mental health.

6483 Diaphyseal Medullary Stenosis With Malignant Fibrous Histiocytoma: A Rare Skeletal Dysplasia/Sarcoma Syndrome

Abstract Disclosure: A. Grover: None. C.R. Ferreira: None. R.I. Gafni: None. S. Jumani: None. M.T. Collins: None. K.L. Roszko: None. I.R. Hartley: None. Introduction: Diaphyseal medullary stenosis with malignant fibrous histiocytoma (DMS-MFH) is a rare autosomal dominant syndrome associated with pathologic fractures, myopathy, premature hair graying, and aggressive osteosarcomas. DMS-MFH has been linked to genetic variants in the methylthioadenosine phosphorylase (MTAP) gene, which encodes an enzyme in the methionine salvage and polyamine synthesis pathway. This pathway is implicated in other skeletal fragility disorders, such as Snyder-Robinson syndrome, suggesting a still undefined role of this pathway in bone biology. We describe a kindred with DMS-MFH and identify diagnostic challenges. Case: A 53-year-old perimenopausal woman presented with four fragility fractures over one year. Relevant history included premature hair graying, esophageal strictures, and nephrolithiasis. The patient’s bone formation markers were slightly elevated; bone resorption markers were within reference range. Her only osteoporosis risk factor was perimenopausal status. Bone series showed a diffuse heterogeneous appearance of the long bones with a mixed lytic/sclerotic appearance. DEXA scan revealed osteopenia. Family history was significant for 2 sons with aggressive osteosarcomas diagnosed in their late teens; one died at age 20. The other son is currently 39-years-old with recurrent osteosarcomas in three different limbs. The family also has a multigenerational history of severe bone fragility, muscle weakness, and premature hair graying. The patient, her living son, and his father underwent genome sequencing that identified a variant in MTAP (c.885A&amp;gt;G; p.(R295=)) in the patient and son. This variant was previously reported in three other families with DMS-MFH and has been shown to alter splicing. Notably, commercial genetic testing did not report this as a relevant variant, and diagnosis required independent analysis of the raw sequence data. Based on these findings, the patient and her son were diagnosed with DMS-MFH. Given the bone fragility with elevated bone turnover markers we treated the patient with yearly zoledronic acid infusions with no subsequent fractures. Surveillance for osteosarcoma is also being performed with annual whole-body MRI. Conclusion: DMS-MFH has been reported in only five families to date. The sixth family described here has clinical characteristics similar to the other kindreds. Due to high risk of aggressive osteosarcoma, timely diagnosis is imperative to decrease morbidity and mortality. Commercial genome sequencing may miss this diagnosis, so targeted genetic testing should be pursued. As more cases are identified, characterization of affected families may enhance our understanding of the natural history of the disease and guide surveillance and treatment strategies. Presentation: 6/2/2024

Hair Graying: Mechanisms, Prevention, and Innovative Treatment Strategies – literature review

Hair graying, or canities, is a complex biological process characterized by the progressive loss of hair pigment, often leading to aesthetic and psychological concerns. This review delves into the multifactorial nature of hair graying, examining the underlying biochemical and physiological mechanisms. Key contributors include oxidative stress, genetic and environmental factors, and disturbances in melanogenesis and signaling pathways such as Notch and Kit. Our extensive literature review from PubMed, involving 33 scientifically rigorous papers, explores the efficiency of various strategies aimed at delaying or preventing hair graying. We highlight the roles of antioxidants, lifestyle modifications, and advanced therapeutic approaches like genetic therapy and liposome delivery systems. Additionally, we explore the impact of diet and UV protection, among other factors, on maintaining hair pigmentation. This review underscores the intricate interplay of biochemical processes in hair graying and sheds light on promising interventions for managing this natural yet often unwelcome sign of aging.

Genetic analysis of a Chinese pedigree affected with Branchio-oculo-facial syndrome and a literature review

To explore the genetic etiology of a Chinese pedigree affected with Branchio-oculo-facial syndrome (BOFS) and summarize the prenatal phenotype of BOFS patients. A pedigree with BOFS which had presented at the Genetics and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University in December 2021 was selected as the study subject. Clinical data of the pedigree was collected. The fetus was subjected to routine prenatal ultrasound scan. Trio-whole exome sequencing (trio-WES) was carried out for the fetus and its parents, and candidate variant was verified by Sanger sequencing. Relevant literature was searched from the database to summarize the prenatal phenotype of BOFS patients. Ultrasound exam suggested the fetus had cleft lip and palate. Its father had presented with high palatal arch, prematurely grayed hair, occult cleft lip, congenital preauricular fistula, red-green color blindness and unilateral renal agenesis. Its grandfather also had high palatal arch, prematurely gray hair, protruding ears, congenital preauricular fistula and hearing disorders. Trio-WES revealed that the fetus and its father had both harbored a heterozygous c.890-1G>A variant of the TFAP2A gene. The same variant was not found in its mother. Sanger sequencing confirmed that its grandfather had also harbored the same variant. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was rated as likely pathogenic (PVS1+PM2_Supporting). Combined with 36 similar cases retrieved from the literature, the prenatal phenotypes of BOFS patients had included growth restriction (25/37), renal abnormalities (10/37), cleft lip and palate (5/37) and oligohydramnios (5/37). The c.890-1G>A variant of the TFAP2A gene probably underlay the pathogenesis of BOFS in this pedigree. Discovery of the novel variant has enriched the mutational spectrum of the TFAP2A gene. The common prenatal phenotypes of BOFS have included growth restriction, renal abnormalities, cleft lip and palate and oligohydramnios. Delineation of the intrauterine phenotype of BOFS may facilitate its prenatal diagnosis, clinical diagnosis, treatment and genetic counseling.

Multi-Label Conditional Generation From Pre-Trained Models.

Although modern generative models achieve excellent quality in a variety of tasks, they often lack the essential ability to generate examples with requested properties, such as the age of the person in the photo or the weight of the generated molecule. To overcome these limitations we propose PluGeN (Plugin Generative Network), a simple yet effective generative technique that can be used as a plugin for pre-trained generative models. The idea behind our approach is to transform the entangled latent representation using a flow-based module into a multi-dimensional space where the values of each attribute are modeled as an independent one-dimensional distribution. In consequence, PluGeN can generate new samples with desired attributes as well as manipulate labeled attributes of existing examples. Due to the disentangling of the latent representation, we are even able to generate samples with rare or unseen combinations of attributes in the dataset, such as a young person with gray hair, men with make-up, or women with beards. In contrast to competitive approaches, PluGeN can be trained on partially labeled data. We combined PluGeN with GAN and VAE models and applied it to conditional generation and manipulation of images, chemical molecule modeling and 3D point clouds generation.

An intronic copy number variation in Syntaxin 17 determines speed of greying and melanoma incidence in Grey horses

The Greying with age phenotype in horses involves loss of hair pigmentation whereas skin pigmentation is not reduced, and a predisposition to melanoma. The causal mutation was initially reported as a duplication of a 4.6 kb intronic sequence in Syntaxin 17. The speed of greying varies considerably among Grey horses. Here we demonstrate the presence of two different Grey alleles, G2 carrying two tandem copies of the duplicated sequence and G3 carrying three. The latter is by far the most common allele, probably due to strong selection for the striking white phenotype. Our results reveal a remarkable dosage effect where the G3 allele is associated with fast greying and high incidence of melanoma whereas G2 is associated with slow greying and low incidence of melanoma. The copy number expansion transforms a weak enhancer to a strong melanocyte-specific enhancer that underlies hair greying (G2 and G3) and a drastically elevated risk of melanoma (G3 only). Our direct pedigree-based observation of the origin of a G2 allele from a G3 allele by copy number contraction demonstrates the dynamic evolution of this locus and provides the ultimate evidence for causality of the copy number variation of the 4.6 kb intronic sequence.

Intrinsic and Extrinsic Factors Associated with Hair Graying (Canities) and Therapeutic Potential of Plant Extracts and Phytochemicals

This review aims to gain insight into the major causes of hair graying (canities) and how plant-derived extracts and phytochemicals could alleviate this symptom. Research articles on human hair graying were searched and selected using the PubMed, Web of Science, and Google Scholar databases. We first examined the intrinsic and extrinsic factors associated with hair graying, such as the reduced capacity of melanin synthesis and transfer, exhaustion of melanocyte stem cells (MSCs) and melanocytes, genetics and epigenetics, race, gender, family history, aging, oxidative stress, stress hormones, systematic disorders, nutrition, smoking, alcohol consumption, lifestyle, medications, and environmental factors. We also examined various plants and phytochemicals that have shown a potential to interfere with the onset or progression of human hair graying at different levels from in vitro studies to clinical studies: the extract of Polygonum multiflorum and its major components, 2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside and emodin; the extract of Eriodictyon angustifolium and its major flavonoid compounds, hydroxygenkwanin, sterubin, and luteolin; the extracts of Adzuki beans (Vigna angularis), Fuzhuan brick tea (Camellia sinensis), and Gynostemma pentaphyllum; bixin, a carotenoid compound found in Bixa orellana; and rhynchophylline, an alkaloid compound found in certain Uncaria species. Experimental evidence supports the notion that certain plant extracts and phytochemicals could alleviate hair graying by enhancing MSC maintenance or melanocyte function, reducing oxidative stress due to physiological and environmental influences, and managing the secretion and action of stress hormones to an appropriate level. It is suggested that hair graying may be reversible through the following tactical approaches: selective targeting of the p38 mitogen-activated protein kinase (MAPK)–microphthalmia-associated transcription factor (MITF) axis, nuclear factor erythroid 2-related factor 2 (NRF2), or the norepinephrine–β2 adrenergic receptor (β2AR)–protein kinase A (PKA) signaling pathway.

Fuzzy Soft Intuitionistic Matrix in Vitiligo

The advanced fuzzy soft matrices are being used in many real-life situations at present days. Fuzzy soft matrices can solve the problem that can’t be solved by ordinary matrices. Main goal of this paper is to describe the Intuitionistic Fuzzy soft matrices and find their properties. In this paper patchy loss on body folds, white patch appears places that have been injured in the past, patchy loss of skin color, premature whitening or graying hair, loss of color in Muscous membranes marked by disorientation is taken as important parameters of vitiligo disease diagnosis. Eventually it concludes that the question of making is based on one of Intuitionistic Fuzzy Soft Matrices Operations.

The health implications of using hair dyes

The global rise in hair dye usage for cosmetic purposes, including gray hair coverage, is prevalent among all genders. Hair dyes are classified as permanent, semi-permanent, and temporary, differing in penetration and frequency. Concerns about safety persist, as many use hair dye without understanding potential health risks. Ahmadi et al.'s meta-analysis indicated a 10% higher cancer risk associated with hair dye, with greater risk for dark dyes and prolonged use. Takkouche et al. found increased hematological malignancy risk, while Gera et al. noted an 18.8% rise in breast cancer risk. Carcinogenic compounds like nitrosamines and PPD in oxidative dyes raise concerns, highlighting the need for safer alternatives and responsible manufacturing.

Acetyl zingerone methyl ether protects hair against oxidative damage incurred during and after treatment with permanent dyes and helps extend longevity of newly developed hair colour.

Use of permanent hair dyes causes unintended oxidative damage during the short time frame of the dyeing process that leads to perceivable changes in the feel, manageability and appearance of hair. Moreover, after hair has been dyed, regular exposure to the sun as a key environmental stressor continues to stimulate additional oxidative damage and to induce newly developed hair colours to fade prematurely or undergo changes in colour quality. To document the utility of acetyl zingerone methyl ether (MAZ) as a newly designed haircare ingredient to afford extra protection against oxidative damage and safeguard the integrity of hair colour. We demonstrate that MAZ is compatible chemically with the high alkaline conditions required for the colouring process and from theoretical calculations preferentially binds Fe and Cu ions relative to Ca or Zn ions. In model Fenton reactions MAZ effectively chelated active redox metals (Fe and Cu ions) in the presence of excess Ca+2 ions to inhibit the production of hydroxyl radicals, and in separate studies, MAZ neutralized singlet oxygen with greater efficiency than α-tocopherol by a factor of 2.5. When mixed into permanent dyes prior to hair tress application, MAZ significantly reduced combing forces, and SEM images led to substantial reductions in visual signs of surface damage. In a 28-day clinical study, relative to controls, mixing MAZ into hair dyes prior to application interfered neither with colour development nor with ability to cover grey hair and led to significant improvements in perceived attributes associated with hair's condition immediately following the dyeing process. Over a 28-day maintenance phase, especially between Day 14 and Day 28, continued use of shampoo and conditioner containing MAZ significantly preserved gloss measurements and hair colour in terms of longevity and colour quality as remaining desired and fresh compared to use of control shampoo and conditioner. This work establishes MAZ as a next-generation hair care ingredient for use in permanent dyes to attenuate oxidative damage and in shampoos and conditioners to promote longevity of hair colour and to maintain overall health and appearance of hair on a daily basis.

Leur Algérie de Lina Soualem : Inscrire la mémoire de l’immigration algérienne dans « la France du vide »

This essay focuses on Leur Algérie, a 2020 documentary about remembering and representing the Algerian experience of immigrating to France’s “rural desert”—or to what geographer Roger Béteille calls “la France du vide.” The context for this analysis lies in the decline of the aging chibanis (North African “elders” or “grey hair”) population in France. While the social issues they face (ranging from lodging, to pension, health, and social benefits) have received media and political attention, questions about their memory and its place in contemporary France point to a “vide mémoriel” (memory void) that has largely been filled by French cultural figures of Maghrebi descent. Thus, with Leur Algérie (2020), filmmaker Lina Soualem delves into the history of her paternal grandparents. Originally from the Laaouamer area in rural Kabylia, they raised their family in France, specifically Thiers, a small French town in the sparsely populated mountains of the Massif Central. This essay examines how Soualem uses scenery and silence to symbolize a memorial void and absence. It relates images of desert-like emptiness and “non-places” in both Thiers and Laaouamer to the gaps in the grandparents’ narrative. Ultimately, it explores tensions between the experiences of Algerian immigrants in France and what Soualem identifies as their “invisibilization” in France’s memorial space.

Gray hair and pink slips: An analysis of Twitter responses to gendered ageism

When Canadian broadcaster, Lisa LaFlamme, announced in August 2022 that CTV National News did not renew her contract, some observers suggested that the corporation’s decision resulted from LaFlamme’s choice to “let her hair go gray” during the pandemic. An international public outcry ensued on Twitter. Our study involved an examination of these tweets (n = 440). Analyses revealed that approximately 80 percent of tweets indicated opposition to LaFlamme’s dismissal, while only 2 percent indicated support and 18 percent indicated a neutral position. Among tweets expressing opposition, the most common justification, found in 79 percent of these tweets, centered on assessments of the employer’s decision as poor. The frequency of all other justifications for opposition was considerably lower, with only 26 percent of these tweets mentioning ageism, 22 percent mentioning sexism, and 20 percent mentioning a general sense of unfairness to LaFlamme. These findings suggest the salience of capitalist logics in shaping how the public frames gendered ageism in the workplace. Our analyses also suggest a view of responses to this inequality as personal bodywork choices. Together, these framings reflect a more individual- than structural-level critique of gendered ageism, knowledge of which can inform efforts to dismantle it.

Detection of trace levels of selected allergic chemicals in commercial hair dyes in local market of Jeddah, Saudi Arabia

Hair dyes are now commonly used in Saudi Arabia, and other nations across the world, to cover up grey hairs and/or to modify the natural color of the hair. The principal ingredients of hair dyes are aromatic amines and phenols and which most likely cause allergic reactions, irritated skin, and even cancer in certain cases. Thus, the current study reports the separation and subsequent identification of four chemical constituents namely p-Phenylenediamine (PPD), 3-aminophenol (3AP), resorcinol (RES), and 2-methylresorcinol (2MRS) in 26 commercial hair dyes that represent ten famous brands available in the local market of Jeddah city, Saudi Arabia. High-performance liquid chromatography (HPLC) technique was successfully employed to identify the four chemical compounds using methanol-aqueous solution (10:90 v/v) containing diethanolamine (0.05 %) and ammonium acetate (0.02 M) at pH 5.2 as a proper mobile phase. The column was 150 × 4.6 mm ID and 5 µm Eclipse Plus C18 column and the retention times were 1.26, 3.16, 4.99 and 6.01 min for PPD, 3AP, RES, and 2MRS, respectively. The four standards PPD, 3AP, RES, and 2MRS at 254 nm displayed excellent linear calibration plots in the concentration range 5–100 µg/mL with acceptable correlation coefficients (R2) of 0.9964, 0.9980, 0.9952 and 0.9961, respectively. The low limits of detection (LOD) and quantification (LOQ) based on the standard deviation of the response and the slopes of the plots were found to be equal 7.17, 5.39, 8.33, and 7.47 µg/mL and 23.91, 17.97, 27.75, 24.89 µg/mL for PPD, 3AP, RES, and 2MRS, respectively.

Adequate Nutrition and Premature Hair Graying: A Review of Literature

Adequate Nutrition and Premature Hair Graying: A Review of Literature

Protection of animal welfare and regulation of animal experimentation

To the young recent graduate who is asked which faculty he wants to pursue and who answers us: veterinary medicine because he loves animals, we often find ourselves inclined, referring to the rhetorical wisdom of gray hairs. to suggest to him that he should abandon the youthful illusion that our profession can enable him to keep these feelings intact, but rather to look at the veterinary profession as a profession that is carried out in the service of society, in a spasmodic attempt to please it in all its innumerable needs or whims, almost all of which are oriented toward the exploitation of animals.