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Fulltext Adeno-tonsillar hypertrophy as a cause of sleep apnoea syndrome

Ravindran VK

Med J Malaysia, 1983 Jun;38(2):164-6.
PMID: 6621450

An interesting case is described here in which partial airway obstruction resulted in sleep apnoea and which was relieved by adeno-tonsillectomy. Enlarged tonsils and adenoids causing upper airway obstruction represent one facet of a continuum of hypoventilation - sleep disorders and clinical examination with x-rays will help in determining patients at risk of developing these syndromes.

Matched MeSH terms: Pigmentation Disorders*
Long-term phenothiazine administration and the eye in 100 Malaysians

Ngen CC, Singh P

Br J Psychiatry, 1988 Feb;152:278-80.
PMID: 3167349

Seventy-three out of a hundred Malaysians on phenothiazines for more than 24 months had ocular pigmentation. Seventy-one had conjunctiva pigmentation. No pigmentary retinopathy or visual impairment was detected. Frequency of pigmentation increased with age and with higher total dosage prescribed, but there was no critical level below which pigmentation was not detected.

Matched MeSH terms: Pigmentation/drug effects*
Fulltext Antioxidant Activity Evaluation of FlexirubinType Pigment from Chryseobacterium artocarpi CECT 8497 and Related Docking Study

Mogadem A, Almamary MA, Mahat NA, Jemon K, Ahmad WA, Ali I

Molecules, 2021 Feb 12;26(4).
PMID: 33673263 DOI: 10.3390/molecules26040979

The current research is focused on studying the biological efficacy of flexirubin, a pigment extracted from Chryseobacterium artocarpi CECT 8497.Different methods such as DPPH, H2O2, NO•, O2•-, •OH, lipid peroxidation inhibition by FTC and TBA, ferric reducing and ferrous chelating activity were carried out to evaluate the antioxidant activity of flexirubin. Molecular docking was also carried out, seeking the molecular interactions of flexirubin and a standard antioxidant compound with SOD enzyme to figure out the possible flexirubin activity mechanism. The new findings revealed that the highest level of flexirubin exhibited similar antioxidant activity as that of the standard compound according to the H2O2, •OH, O2•-, FTC and TBA methods. On the other hand, flexirubin at the highest level has shown lower antioxidant activity than the positive control according to the DPPH and NO• and even much lower when measured by the FRAP method. Molecular docking showed that the interaction of flexirubin was in the binding cavity of the SOD enzyme and did not affect its metal-binding site. These results revealed that flexirubin has antioxidant properties and can be a useful therapeutic compound in preventing or treating free radical-related diseases.

Matched MeSH terms: Pigmentation/drug effects
Objective assessment of psoriasis erythema for PASI scoring

Ahmad Fadzil MH, Ihtatho D, Affandi AM, Hussein SH

Annu Int Conf IEEE Eng Med Biol Soc, 2008;2008:4070-3.
PMID: 19163606 DOI: 10.1109/IEMBS.2008.4650103

Skin colour is vital information in dermatological diagnosis. It reflects pathological condition beneath the skin and commonly being used to indicate the extent of a disease. Psoriasis is a skin disease which is indicated by the appearance of red plaques. Although there is no cure for psoriasis, there are many treatment modalities to help control the disease. To evaluate treatment efficacy, PASI (Psoriasis Area and Severity Index) which is the current gold standard method is used to determine severity of psoriasis lesion. Erythema (redness) is one parameter in PASI. Commonly, the erythema is assessed visually, thus leading to subjective and inconsistent result. In this work, we proposed an objective assessment of psoriasis erythema for PASI scoring. The colour of psoriasis lesion is analyzed by DeltaL, Deltahue, and Deltachroma of CIELAB colour space. References of lesion with different scores are obtained from the selected lesions by two dermatologists. Results based on 38 lesions from 22 patients with various level of skin pigmentation show that PASI erythema score can be determined objectively and consistent with dermatology scoring.

Matched MeSH terms: Skin Pigmentation*
Fulltext Little White Lies: Pericarp Color Provides Insights into the Origins and Evolution of Southeast Asian Weedy Rice

Cui Y, Song BK, Li LF, Li YL, Huang Z, Caicedo AL, et al.

G3 (Bethesda), 2016 Dec 07;6(12):4105-4114.
PMID: 27729434 DOI: 10.1534/g3.116.035881

Weedy rice is a conspecific form of cultivated rice (Oryza sativa L.) that infests rice fields and results in severe crop losses. Weed strains in different world regions appear to have originated multiple times from different domesticated and/or wild rice progenitors. In the case of Malaysian weedy rice, a multiple-origin model has been proposed based on neutral markers and analyses of domestication genes for hull color and seed shattering. Here, we examined variation in pericarp (bran) color and its molecular basis to address how this trait evolved in Malaysian weeds and its possible role in weed adaptation. Functional alleles of the Rc gene confer proanthocyanidin pigmentation of the pericarp, a trait found in most wild and weedy Oryzas and associated with seed dormancy; nonfunctional rc alleles were strongly favored during rice domestication, and most cultivated varieties have nonpigmented pericarps. Phenotypic characterizations of 52 Malaysian weeds revealed that most strains are characterized by the pigmented pericarp; however, some weeds have white pericarps, suggesting close relationships to cultivated rice. Phylogenetic analyses indicate that the Rc haplotypes present in Malaysian weeds likely have at least three distinct origins: wild O. rufipogon, white-pericarp cultivated rice, and red-pericarp cultivated rice. These diverse origins contribute to high Rc nucleotide diversity in the Malaysian weeds. Comparison of Rc allelic distributions with other rice domestication genes suggests that functional Rc alleles may confer particular fitness benefits in weedy rice populations, for example, by conferring seed dormancy. This may promote functional Rc introgression from local wild Oryza populations.

Matched MeSH terms: Pigmentation/genetics*
Fulltext Chemotherapeutic trials in leprosy. 6. Pilot study of the riminophenazine derivative B.663 in low dosage (100 mgm. twice weekly) in the treatment of lepromatous leprosy

Waters MFR

Int. J. Lepr. Other Mycobact. Dis., 1968;36(4):391-9.
PMID: 4898403

Using a trial design previously evolved at Sungei Buloh Leprosarium, a pilot trial was performed of B.663, in the dosage of 100 mgm. twice weekly, in eight patients with previously untreated lepromatous leprosy. The therapeutic results, as measured by clinical, bacteriologic and histologic assessment, and especially by the rate of fall of the morphologic index, were similar to those obtained with sulfone therapy or with 0.663 in the dosage of 300 mgm. daily. Although B.663 pigmentation was produced in all eight patients, it developed more slowly and was less intense than with standard dosage. Difficulties resulting from skin discoloration in assessing the clinical progress of patients on B.663 are discussed.

Matched MeSH terms: Pigmentation/drug effects
Fulltext Factors influencing pulse oximetry as compared to functional arterial saturation in multi-ethnic Singapore

Lee KH, Hui KP, Tan WC, Lim TK

Singapore Med J, 1993 Oct;34(5):385-7.
PMID: 8153680

Noninvasive oximetry provides continuous monitoring of arterial oxygen saturation and hence, early detection of hypoxia. This has proved to be a useful adjunct to patients' safety, and is considered indispensable in certain settings. However, errors may be present in the pulse oximeter estimation (SpO2) of arterial oxygen saturation (SaO2), which may be due to various parameters. We have studied a multi-ethnic population where the skin pigmentation is different, and also under different conditions comparing SpO2 with SaO2. Our results showed that SpO2 estimation of SaO2 amongst the three racial groups (Chinese, Malays, and Indians) varied significantly (ANOVA, p < 0.05). The over-estimation was more pronounced by hypoxic conditions and jaundice. Haemoglobin and systolic blood pressure did not affect the difference between SpO2 and SaO2.

Matched MeSH terms: Skin Pigmentation/physiology
A broad assessment of forty-one skin phenotypes reveals complex dimensions of skin ageing

Ng JY, Wong QYA, Lim JJ, Cen D, Wong JYK, Lim YYE, et al.

J Physiol Anthropol, 2025 Feb 08;44(1):3.
PMID: 39923103 DOI: 10.1186/s40101-024-00383-2

BACKGROUND: Skin ageing takes on many different forms. Despite this diversity in skin ageing phenotypes, literature published to date is limited in scope, as many research studies either focus on one single phenotype or just a few specific phenotypes. Presently, phenotypes such as wrinkles, pigment spots, and photo-ageing are receiving most of the research attention. We therefore wonder whether the current discourse on skin ageing places a disproportionate amount of focus on a few selected phenotypes, leaving other skin ageing phenotypes underexplored.
METHODS: In this cross-sectional study, we performed a broad assessment of forty-one signs of skin ageing and characterised the phenotypes that constituted key components of skin ageing. We also explored the interrelationship among forty-one skin ageing phenotypes using Spearman's Correlation and Principal Component Analysis.
RESULTS: We analysed our study population, which is composed of 3281 ethnic Chinese participants from the Singapore/Malaysia Cross-sectional Genetics Epidemiology Study (SMCGES). The first ten principal components cumulatively explain 46.88% of the variance of skin ageing phenotypes in our study population. We discovered that the commonly discussed forms of skin ageing (i.e., wrinkles, pigmentation, and photo-ageing) only accounted for a small portion (24.39%) of the variance of all skin ageing phenotypes in our study population. Telangiectasia, a poor lip fullness, a lighter skin colour, xerosis, ephelides (freckles), ptosis of eyelids (droopy eyelids), eyebags, and a low eyebrow positioning were other key components of skin ageing, accounting for a further 22.49% of the variance of skin ageing phenotypes in our study population. We found that each of these ten skin ageing phenotypes characterises a key and important aspect of skin ageing. In this broad assessment of skin ageing, we first described the prevalence of forty-one signs of skin ageing and then characterised in detail both the prevalence and severity distribution of ten key skin ageing phenotypes.
CONCLUSIONS: We presented clear evidence that skin ageing is much more than just wrinkles, pigmentation and photo-ageing. The addition of telangiectasia, poor lip fullness, a lighter skin colour, xerosis, ephelides, ptosis of eyelids, eyebags, and a low eyebrow positioning added more dimensions to skin ageing phenotype presentations.

Matched MeSH terms: Skin Pigmentation/physiology
Fulltext A case of the Hutchinson-Gilford progeria syndrome

Omar A

Med J Malaysia, 1982 Dec;37(4):362-4.
PMID: 7167089

A case of the Hutchinson-Gilford progeria syndrome (HGPS) in Malaysia is described. A brief discussion of this rare condition and its differential diagnosis follows.

Matched MeSH terms: Skin Pigmentation
Fulltext Borneo coral reefs subject to high sediment loads show evidence of resilience to various environmental stressors

Browne N, Braoun C, McIlwain J, Nagarajan R, Zinke J

PeerJ, 2019;7:e7382.
PMID: 31428541 DOI: 10.7717/peerj.7382

For reefs in South East Asia the synergistic effects of rapid land development, insufficient environmental policies and a lack of enforcement has led to poor water quality and compromised coral health from increased sediment and pollution. Those inshore turbid coral reefs, subject to significant sediment inputs, may also inherit some resilience to the effects of thermal stress and coral bleaching. We studied the inshore turbid reefs near Miri, in northwest Borneo through a comprehensive assessment of coral cover and health in addition to quantifying sediment-related parameters. Although Miri's Reefs had comparatively low coral species diversity, dominated by massive and encrusting forms of Diploastrea, Porites, Montipora, Favites, Dipsastrea and Pachyseris, they were characterized by a healthy cover ranging from 22 to 39%. We found a strong inshore to offshore gradient in hard coral cover, diversity and community composition as a direct result of spatial differences in sediment at distances <10 km. As well as distance to shore, we included other environmental variables like reef depth and sediment trap accumulation and particle size that explained 62.5% of variation in benthic composition among sites. Miri's reefs showed little evidence of coral disease and relatively low prevalence of compromised health signs including bleaching (6.7%), bioerosion (6.6%), pigmentation response (2.2%), scars (1.1%) and excessive mucus production (0.5%). Tagged colonies of Diploastrea and Pachyseris suffering partial bleaching in 2016 had fully (90-100%) recovered the following year. There were, however, seasonal differences in bioerosion rates, which increased five-fold after the 2017 wet season. Differences in measures of coral physiology, like that of symbiont density and chlorophyll a for Montipora, Pachyseris and Acropora, were not detected among sites. We conclude that Miri's reefs may be in a temporally stable state given minimal recently dead coral and a limited decline in coral cover over the last two decades. This study provides further evidence that turbid coral reefs exposed to seasonally elevated sediment loads can exhibit relatively high coral cover and be resilient to disease and elevated sea surface temperatures.

Matched MeSH terms: Pigmentation
Fulltext Comprehensive proteomics data on whole rice grain of selected pigmented and non-pigmented rice varieties using SWATH-MS approach

Sew YS, Aizat WM, Razak MSFA, Zainal-Abidin RA, Simoh S, Abu-Bakar N

Data Brief, 2020 Aug;31:105927.
PMID: 32642524 DOI: 10.1016/j.dib.2020.105927

The proteome data of whole rice grain is considerably limited particularly for rice with pigmentations such as black and red rice. Hence, we performed proteome analysis of two black rice varieties (BALI and Pulut Hitam 9), two red rice varieties (MRM16 and MRQ100) and two white rice varieties (MR297 and MRQ76) using label-free liquid chromatography Triple TOF 6600 tandem mass spectrometry (LC-MS/MS). Our aim was to profile and identify proteins related to nutritional (i.e. antioxidant, folate and low glycaemic index) and quality (i.e. aromatic) traits based on peptide-centric scoring from the Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS) approach. Both information dependent acquisition (IDA) and SWATH-MS run were performed in this analysis. Raw data was then processed using ProteinPilot software to identify and compare proteins from the six different varieties. In future, this proteomics data will be integrated with previously obtained genomics [1] and transcriptomics [2] data focusing on the above nutritional and quality traits, with an ultimate aim to develop a panel of functional biomarkers related to those traits for future rice breeding programme. The raw MS data of the pigmented and non-pigmented rice varieties have been deposited to ProteomeXchange database with accession number PXD018338.

Matched MeSH terms: Pigmentation
Fulltext The Integration of a Dual-Wavelength Super Pulsed Diode Laser for Consistent Tissue Ablation in the Esthetic Zone: A Case Series

Kamar Affendi NH, Ahmad R, Vahidi F, Hassan MZ, Rahimi SN

Case Rep Dent, 2020;2020:8883156.
PMID: 33343944 DOI: 10.1155/2020/8883156

Introduction: A diode laser is one of the universally compact accepted laser systems used fundamentally for soft tissue applications. Most diode laser devices have a single wavelength of either 810 nm for superior coagulation or 980 nm for tissue ablation. In these case series, the use of dual wavelengths (810 nm and 980 nm) in combination with super pulsing has provided a cleaner cut (no charring) with faster healing that eases the placement of the final restoration in the esthetic zone. Case Description. The present case series describe four cases in the esthetic zone that achieved hemostasis ablation without collateral damage to enhance gingival balance of definitive restoration. The gingivoplasty and gingivectomy modes are used to achieve efficient tissue ablation. Although there is no specific mode indicated in the FDA laser requirement for gingival depigmentation, the procedure could be safely performed with the dual-wavelength diode laser.
Result: All four patients revealed a good esthetic outcome and reported no pain postoperatively. Healing was uneventful, and definitive restoration was delivered within two to four weeks postoperatively.
Conclusion: Within the limitation of these case series, the dual-wavelength super pulsed diode laser has the capacity to deliver peak powers resulting in efficient cutting and less tissue charring and also as an alternative tool for removal of gingival pigmentation. Prospective clinical research with larger sample size is needed for conclusive results.

Matched MeSH terms: Pigmentation
Fulltext Antioxidant properties of total lutein content in different parts of pumpkin (Cucurbita maxima)

WONG YEN WEN, FAUZIAH TUFAIL AHMAD

UMT Journal of Undergraduate Research, 2020;2(3):27-34.
MyJurnal

Pumpkin (Cucurbita maxima) is a vegetable crop which is commonly consumed as vegetables or incorporated into food products. Pumpkin flesh was reported abundant with carotenoid compounds includes α-carotene, β-carotene, β-cryptoxanthin, lutein and zeaxanthin. As this antioxidant related to the colour pigment, these nutrients highly potential to be in other parts of pumpkin such as peel and seed. Therefore, the aim of this was to determine the total lutein content in different parts of pumpkin and their antioxidant properties. The pumpkin would be collected and evaluated at the commercial maturity stage (60% to fully orange-yellow of fruit peel). The presence of the lutein properties using DPPH, FRAP and ABTS assays in different parts of pumpkin was tested by using microplate spectrophotometer and analysed statistically with SPSS version 20. Among of all pumpkin fruit parts, flesh presented the highest concentration of potential lutein extracts, followed by peel and seed, respectively. On the contrary, potential lutein extracts from the pumpkin peel had the highest antioxidant activity in terms of DPPH, FRAP and ABTS assays when compared to the lutein extracts in flesh and seeds. This study indicates that the potential lutein from Cucurbita maxima especially peel may be the alternative to be used as both natural antioxidants in food products due to increasing demand for natural food preservatives. Therefore, this study may act as a source for others to further study to optimize the usage of pumpkin by-products

Matched MeSH terms: Pigmentation
Isolation of a Pigment-producing Strain of Staphylococcus kloosii from the Respiratory Tree of Holothuria (Mertensiothuria) leucospilota () from Malaysian Waters

Kamarudin KR, Ngah N, Hamid TH, Susanti D

Trop Life Sci Res, 2013 Aug;24(1):85-100.
PMID: 24575244

Staphylococcus kloosii, an orange pigment-producing bacterium, was isolated from the respiratory tree of Holothuria (Mertensiothuria) leucospilota (Brandt 1835) from Teluk Nipah, Pangkor Island, Perak, Malaysia. This report is the first documentation of this Gram-positive strain, referred to as Strain 68 in Malaysia. A partial 16S ribosomal RNA gene sequence of the mesophilic strain has been registered with GenBank (National Center for Biotechnology Information, US National Library of Medicine) with accession number JX102547. Phylogenetic analysis using the neighbour-joining method further supported the identification of Strain 68 as S. kloosii. The circular strain produced orange pigments on tryptone glucose yeast extract agar (TGYEA) and in nutrient broth (NB) at approximately pH 7. The visible spectra of ethanolic and methanolic pigment extracts of the bacterial strain were considered identical with λmax at 426, 447 and 475 nm and λmax at 426, 445 and 473 nm, respectively. Both visible spectra resemble the visible spectra of lutein, which is a commercial carotenoid; however, further analyses are required to confirm the identity of this pigment. The methanolic extracts of the intracellular pigments comprised at least three pigment compounds: an orange pigment compound (major compound), a yellow pigment compound (the least polar) and a pink pigment compound (the most polar). These findings are the first documentation of the pigment composition of S. kloosii as no such record could be found to date.

Matched MeSH terms: Pigmentation
Source Determination of Red Gel Pen Inks using Raman Spectroscopy and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy combined with Pearson's Product Moment Correlation Coefficients and Principal Component Analysis

Mohamad Asri MN, Mat Desa WNS, Ismail D

J Forensic Sci, 2018 Jan;63(1):285-291.
PMID: 28480527 DOI: 10.1111/1556-4029.13522

The potential combination of two nondestructive techniques, that is, Raman spectroscopy (RS) and attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy with Pearson's product moment correlation (PPMC) coefficient (r) and principal component analysis (PCA) to determine the actual source of red gel pen ink used to write a simulated threatening note, was examined. Eighteen (18) red gel pens purchased from Japan and Malaysia from November to December 2014 where one of the pens was used to write a simulated threatening note were analyzed using RS and ATR-FTIR spectroscopy, respectively. The spectra of all the red gel pen inks including the ink deposited on the simulated threatening note gathered from the RS and ATR-FTIR analyses were subjected to PPMC coefficient (r) calculation and principal component analysis (PCA). The coefficients r = 0.9985 and r = 0.9912 for pairwise combination of RS and ATR-FTIR spectra respectively and similarities in terms of PC1 and PC2 scores of one of the inks to the ink deposited on the simulated threatening note substantiated the feasibility of combining RS and ATR-FTIR spectroscopy with PPMC coefficient (r) and PCA for successful source determination of red gel pen inks. The development of pigment spectral library had allowed the ink deposited on the threatening note to be identified as XSL Poppy Red (CI Pigment Red 112).

Matched MeSH terms: Pigmentation
Fulltext Response to intradermal autologous platelet rich plasma injection in refractory dermal melasma: report of two cases

Yew, C.H., Ramasamy, T.S., Amini, F.

JUMMEC, 2015;18(2):1-6.
MyJurnal

Refractory dermal melasma is resistant to conventional treatment. Platelet rich plasma (PRP) may help to reduce the pigmentation of melasma. We present a case report on the clinical outcome of 2 patients with melasma, given PRP, as an adjunct therapy. PRP was administered at a monthly interval for 2 sessions in combination with a monthly Q-switched Nd Yag laser treatment and topical alpha arbutin application. A modified melasma area and severity index (MASI) was evaluated by two dermatologists who were blinded. At the follow up on the 3rd months, the MASI score was reduced by mean 33.5% for case 1 and 20% for case 2. There were no clinical complications for case 1. However recurrence of melasma was noted in case 2 by a worsening of the MASI score mean to 53% at the sixth months follow up. In conclusion, intradermal PRP injection as an adjunct to the conventional treatment of melasma presented with differing results in two cases.

Matched MeSH terms: Pigmentation
Fulltext Different ommochrome pigment mixtures enable sexually dimorphic Batesian mimicry in disjunct populations of the common palmfly butterfly, Elymnias hypermnestra

Panettieri S, Gjinaj E, John G, Lohman DJ

PLoS One, 2018;13(9):e0202465.
PMID: 30208047 DOI: 10.1371/journal.pone.0202465

With varied, brightly patterned wings, butterflies have been the focus of much work on the evolution and development of phenotypic novelty. However, the chemical structures of wing pigments from few butterfly species have been identified. We characterized the orange wing pigments of female Elymnias hypermnestra butterflies (Lepidoptera: Nymphalidae: Satyrinae) from two Southeast Asian populations. This species is a sexually dimorphic Batesian mimic of several model species. Females are polymorphic: in some populations, females are dark, resemble conspecific males, and mimic Euploea spp. In other populations, females differ from males and mimic orange Danaus spp. Using LC-MS/MS, we identified nine ommochrome pigments: six from a population in Chiang Mai, Thailand, and five compounds from a population in Bali, Indonesia. Two ommochromes were found in both populations, and only two of the nine compounds have been previously reported. The sexually dimorphic Thai and Balinese populations are separated spatially by monomorphic populations in peninsular Malaysia, Singapore, and Sumatra, suggesting independent evolution of mimetic female wing pigments in these disjunct populations. These results indicate that other butterfly wing pigments remain to be discovered.

Matched MeSH terms: Pigmentation
Fulltext Carotenoids of Capsicum Fruits: Pigment Profile and Health-Promoting Functional Attributes

Mohd Hassan N, Yusof NA, Yahaya AF, Mohd Rozali NN, Othman R

Antioxidants (Basel), 2019 Oct 09;8(10).
PMID: 31600964 DOI: 10.3390/antiox8100469

Pepper of the Capsicum species is a common ingredient in various food preparations by different cultures worldwide. The Capsicum is recognised by its five main domesticated species, namely Capsicum annuum, C. baccatum, C. chinense, C. frutescens and C. pubescens. The genetic diversity in Capsicum offers fruits in wide ranges of morphology and carotenoid profile. Carotenoids enhance the value of pepper from a nutritional standpoint, despite being commonly prized for the pharmacologically active pungent capsaicinoids. Carotenoids of pepper comprise mainly of the unique, powerful and highly stable capsanthin and capsoroubin, together with β-carotene, β-cryptoxanthin, lutein, zeaxanthin, antheraxanthin and violaxanthin. These carotenoids are present at diverse profile and varying levels, biosynthetically connected to the fruit maturity stages. This review describes the health-promoting functional attributes of the carotenoids that are mainly associated with their excellent role as lipophilic antioxidants. Capsicum as a great source of carotenoids is discussed in the aspects of main domesticated species, biosynthesis, pigment profile, antioxidant activity and safety. Findings from a number of in vitro, in vivo and clinical studies provided appreciable evidence on the protective effects of pepper's carotenoids against degenerative diseases. Hence, pepper with its functional carotenoids might be recommended in health-promoting and disease preventing strategies.

Matched MeSH terms: Pigmentation
Cutaneous immune reaction: its usefulness in the evaluation of small-pox immunity in dark races

Doraisingham M

Journal of the Malaya Branch of the British Medical Association, 1940;4:314-18.

1. Observations made on groups of light and dark skinned individuals indicate that the percentage of dark skinned people who can be recognized as immune by their reaction to vaccination is considerably lower than in the case of people with a lesser skin pigmentation.
2. It is suggested that the reading of "immune reaction" is influenced considerably by the intensity of skin pigment found in the individual.
3. It would appear that while the usefulness of immune reaction readings in light-skinned peope is very great, its value is limited when applied to those with dark skins.

Matched MeSH terms: Skin Pigmentation
Fulltext Umbilical Cord Mesenchymal Stromal Cell-Derived Small Extracellular Vesicles Modulate Skin Matrix Synthesis and Pigmentation

Kee LT, Foo JB, How CW, Nur Azurah AG, Chan HH, Mohd Yunus MH, et al.

Int J Nanomedicine, 2025;20:1561-1578.
PMID: 39931529 DOI: 10.2147/IJN.S497940

INTRODUCTION: Research has unveiled the remarkable properties of extracellular vesicles derived from mesenchymal stromal cells (MSCs), particularly in promoting wound healing, aiding re-epithelialization, revitalizing aging skin, and inhibiting hyperpigmentation. However, investigations into the potential of small extracellular vesicles from umbilical cord-derived MSCs (UC-MSC-sEVs) in reducing scarring and preventing hyperpigmentation remain limited. Therefore, this study aims to evaluate the impact of UC-MSC-sEVs on the synthesis of the skin's extracellular matrix (ECM) and pigmentation using in vitro models.
METHODS: The study investigated the impact of characterized UC-MSC-sEVs on various aspects including the proliferation, migration, antioxidant activity, and ECM gene expression of human dermal fibroblasts (HDF). Additionally, the effects of UC-MSC-sEVs on the proliferation, melanin content, and tyrosinase (TYR) activity of human melanoma cells (MNT-1) were examined. Furthermore, ex vivo models were employed to evaluate the skin permeation of PKH26-labelled UC-MSC-sEVs.
RESULTS: The findings indicated that a high concentration of UC-MSC-sEVs positively influenced the proliferation of HDF. However, no changes in cell migration rate were observed. While the expressions of collagen type 1 and type 3 remained unaffected by UC-MSC-sEVs treatment, there were dose-dependent increases in the gene expressions of fibronectin, matrix metallopeptidase (MMP) 1, and MMP 3. Furthermore, UC-MSC-sEVs treatment did not impact the antioxidative superoxide dismutase (SOD) expression in HDF. Although UC-MSC-sEVs did not alter the proliferation of MNT-1 cells, it did result in a dose-dependent reduction in melanin synthesis without affecting TYR activity. However, when it was applied topically, UC-MSC-sEVs failed to penetrate the skin barrier and remained localized within the stratum corneum layer even after 18 hours.
CONCLUSION: These results highlight the potential of UC-MSC-sEVs in stimulating HDF proliferation, regulating ECM synthesis, and reducing melanin production. This demonstrates the promising application of UC-MSC-sEVs in medical aesthetics for benefits such as scar reduction, skin rejuvenation, and skin lightening.

Matched MeSH terms: Skin Pigmentation

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