[Formation of hair and restoration of its innervation in human skin transplantation].
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Hair follicles (HFs) are vital skin appendages that perform fundamental functions including protection, thermoregulation, and sensation. Orchestrated by hair follicle stem cells (HFSCs), HFs undergo cyclic regeneration throughout the lifespan. However, during chronological aging, this mini-organ experiences progressive physiological decline, clinically characterized by a marked reduction in hair density and hair graying due to pigmentation dysfunction. This aging process involves HFSC exhaustion accompanied by diminished regenerative potential and differentiation capacity, leading to degenerative changes in the bulge architecture. Concurrently, the niche supporting HFSC homeostasis undergoes multi-dimensional and systemic degradation. This niche deterioration disrupts the delicate balance between HFSC quiescence and activation, further impeding hair regeneration. In this review, we delineate the dynamic anatomical changes throughout the hair growth cycle and describe the alterations of HFSCs during aging. We specifically focus on the mechanisms underlying the multi-dimensional degradation of the HFSC niche at tissue, cellular, and molecular levels. Furthermore, we discuss various therapeutic strategies aimed at ameliorating HF aging, offering potential insights for future clinical translation in hair regeneration. Finally, we propose that integrating spatiotemporal high-resolution technologies with genomic data to further decipher the spatiotemporal behaviors of aging HFSCs and niche cells will facilitate the establishment of a robust mechanistic framework for HFSC and niche aging.
Plasma and hair zinc concentrations were measured by atomic absorption spectrophotometry in 34 control subjects, 20 nondialyzed uremic patients and 18 patients treated with regular hemodialysis. Plasma zinc levels were low in both nondialyzed and hemodialyzed patients. Hair zinc levels were low in the nondialyzed uremics, but at least partialy restored to normal in patients on hemodialysis. In both patient groups, hair zinc was positively correlated with plasma zinc. In the nondialyzed patients haie zinc depletion in end-stage renal disease progresses with increasing degree of renal insufficiency and tends to be reversed by regular hemodialysis.
A prevalent recessive mutation (c.2485C>T, p.Q829X) within the OTOF gene leads to profound prelingual hearing loss. Here we show that in Otof mice harbouring a mutation (c.2482C>T, p.Q828X) homozygous to human OTOF that faithfully mimics the hearing-loss phenotype, a base editor (consisting of the deaminase ABE7.10max and the Cas9 variant SpCas9-NG) packaged in adeno-associated viruses and injected into the inner ear of the mice via the round-window membrane effectively corrected the pathogenic mutation, with no apparent off-target effects. The treatment restored the levels of the otoferlin protein in 88% of the inner hair cells and stably rescued the auditory function of the mice to near-wild-type levels for over 1.5 years while improving synaptic exocytosis in the inner hair cells. We also show that an adenine base editor that targets the prevalent human OTOF mutation restored hearing in humanized mice to levels comparable to those of the wild-type counterparts. Base editors may be effective for the treatment of hereditary deafness.
Irreversible cisplatin-induced hearing loss (CIHL) is a refractory chemotherapy-related adverse effect with limited clinical treatments. Schisantherin B (STB), a lignan isolated from Schisandra chinensis, is widely recognized for its neuroprotective properties, while its role in auditory injury remains unclear. Herein, we found that STB alleviated cisplatin-induced ototoxicity in House Ear Institute Organ of Corti 1 (HEI-OC1) cells and guinea pig models, protecting cochlear hair cells, synaptic ribbons and spiral ganglion neurons, and partially restoring auditory brainstem response (ABR) thresholds. Furthermore, combined drug affinity responsive target stability (DARTS) assay, the cellular thermal shift assay (CETSA), and the surface plasmon resonance (SPR) assay, we confirmed STB directly binds to the canopy FGF signaling regulator 2 (CNPY2), a key initiator of endoplasmic reticulum (ER) stress. Notably, consistent dual in vitro and in vivo validation confirmed that STB exerts no regulatory effect on CNPY2 protein abundance, yet suppressed the downstream Protein kinase R-like endoplasmic reticulum kinase / C/EBP homologous protein (PERK/CHOP) signaling cascade and ER stress-mediated apoptosis. Moreover, molecular docking and co-immunoprecipitation (co-IP) validated the physical binding of STB to CNPY2 and the endogenous interaction between CNPY2 and PERK. Additionally, CNPY2 overexpression and shRNA knockdown further verified this functional relationship. Integrated proteomic and transcriptomic analyses showed STB partially reversed cisplatin-triggered inflammation and excessive ER stress. Collectively, our results suggest STB may serve as a potential otoprotective agent. The CNPY2-PERK/CHOP axis is closely linked to cisplatin-induced cochlear damage and offers a feasible target for intervention against CIHL. Abbreviations: CIHL, cisplatin-induced hearing loss; STB, Schisantherin B; HEI-OC1, house ear institute organ of corti 1; ABR, auditory brainstem response; DARTS, drug affinity responsive target stability; CETSA, cellular thermal shift assay; SPR, surface plasmon resonance; CNPY2, canopy FGF signaling regulator 2; ER, endoplasmic reticulum; PERK, protein kinase R-like endoplasmic reticulum kinase; CHOP, C/EBP homologous protein; co-IP, co-immunoprecipitation; STA, Schisantherin A; STC, Schisantherin C; dB SPL, decibels sound pressure level; EDTA, ethylenediaminetetraacetic acid; dB SPL, decibels sound pressure level; SGN, spiral ganglion neuron; IHCs, inner hair cells; OHCs, outer hair cells; CCK-8, Cell Counting Kit-8; OD, optical density; ODb, blank sample, ODc, control sample; NC, negative control; PVDF, polyvinylidene difluoride; RT, room temperature; LC-MS/MS, liquid chromatography tandem mass spectrometry; MS, mass spectrometry; DMSO, dimethyl sulfoxide; KDs, equilibrium dissociation constants; SP, standard precision; SEM, standard error of the mean; HSD, honestly significant difference; Ctrl, control group; CV, cell viability; Kd, dissociation rate constant; Ka, association rate constant; STS, sodium thiosulfate; UPR, unfolded protein response; BLB, blood-labyrinth barrier.
A white female, now age 40 and receiving total parenteral nutrition for more than 5 years, developed unexpected 15% weight loss after 3 1/2 years of regimen, together with peripheral neuropathy confirmed by nerve conduction measurements. An intravenous glucose tolerance test showed that the fractional rate (K) had decreased to 0.89%/min (normal greater than 1.2). There was observed during this glucose infusion a borderline normal insulin response with a fall in plasma free fatty acids and in plasma leucine. During daily infusion of well over 400 g of glucose, the respiratory quotient was 0.66. Chromium balance was negative. Chromium levels were, in blood 0.55 ng/ml (normal 4.9 to 9.5) and in hair 154 to 175 ng/g (normal greater than 500). Regular insulin daily (45 micron) in the infusate nearly maintained euglycemia but despite this, and even with further glucose intake to restore weight loss, intravenous glucose tolerance test (K) and respiratory quotient were unchanged. Administration of insulin was then stopped and 250 microng of Cr added to the daily total parenteral nutrition infusate for 2 weeks. After this the intravenous glucose tolerance test (K) and respiratory quotient became normal (1.35 and 0.78, respectively). Over the next 5 months insulin was not needed and glucose intake had to be reduced substantially to avoid overweight. In this period nerve conduction and well-being returned to normal. With a maintenance addition of chromium to the total parenteral nutrition infusate (tentatively this addition is 20 microng/day) the patient has remained well for 18 months (to July 1976). These results suggest that relatively isolated chromium deficiency in man, hitherto poorly documented, causes 1) glucose intolerance, 2) inability to utilize glucose for energy, 3) neuropathy with normal insulin levels, 4) high free fatty acid levels and low respiratory quotient and, 5) abnormalities of nitrogen metabolism.
The transcription factor ATOH1 is a master regulator of mechanosensory hair-cell (HC) development in the ear. Here, we report that its target gene Casz1 regulates the maturation of outer HCs (OHCs). Genetic deletion of Casz1 during (but not after) cochlear development in the mouse caused: hearing loss; disorganization of mechanosensory stereocilia bundles in OHCs; reduced F-actin density in OHC cuticular plates; progressive OHC loss; and mild morphological alterations in inner HCs. This deletion also altered gene expression, delaying downregulation of genes expressed in immature OHCs, including the actin regulator-encoding gene Coro2a, and accelerating upregulation of genes expressed in mature OHCs. Deleting Coro2a in Casz1 mutant mice restored F-actin density in cuticular plates but increased stereocilia bundle disorganization and hearing thresholds, revealing that CORO2A provides an overall beneficial effect. Our data indicate that CASZ1 regulates transcriptional and morphological maturation of OHCs, and that CASZ1 in maturing HCs is necessary for hearing.
Small nucleolar RNAs (snoRNAs) function in ribosome biogenesis, and many ribosome biogenesis-related genes were downregulated by osmotic stress, implying a negative role of snoRNAs in drought tolerance. A snoRNA, namely, the NON-CODING RNA 1 (NCR1) was studied for its roles in drought tolerance in Arabidopsis. In comparison with wild-type (WT) plants, the loss-of-function ncr1 mutant plants showed enhanced drought tolerance, which was restored in the NCR1-complemented plants, whereas the NCR1-overexpressing plants revealed a drought-sensitive phenotype. Physiological analyses revealed that the ncr1 plants had a higher leaf surface temperature, lower water loss rates, and improved cell membrane integrity compared with WT. Comparative leaf transcriptomics and proteomics suggested that wax biosynthesis, anthocyanin metabolism, and leaf senescence processes are regulated by NCR1 under both normal and water-deficit conditions. Under drought, an increase in wax and anthocyanin accumulations and a delay in leaf senescence in ncr1 plants, when compared with WT, supported the transcriptome and proteomics data. Additionally, the ncr1 plants exhibited higher abscisic acid (ABA) sensitivity and longer root hairs than WT. Collectively, our results suggest that NCR1 negatively regulates drought tolerance through modification of wax biosynthesis, anthocyanin accumulation, leaf senescence, cell membrane integrity, ABA responses, and root hair development.
The effect of levamisole on the in vitro responses of splenic and peripheral blood lymphocytes to phytohemagglutinin were investigated in zinc-deprived and pair-fed control rats. The in vitro response of lymphocytes from zinc-deprived rats was markedly impaired in comparison with that of controls. The addition of levamisole to cultures of zinc-deprived splenic lymphocytes significantly improved their response to phytohemagglutinin by 54%. The addition of levamisole to cultures of zinc-deprived peripheral blood lymphocytes significantly improved their response by 116.2%. The addition of levamisole to control lymphocyte culture had no effect. This study may be the first to evaluate the beneficial effect of an immunomodulating agent on immune function in a nutritionally deprived host.