Biotin biochemistry and human requirements

Simultaneous quantification of seven B vitamins from wheat grains using UHPLC-MS/MS

B-group vitamins are important micronutrients for maintaining human health; nevertheless, B vitamin deficiency is a globally widespread issue. Thus, it is relevant to accurately assess the B-vitamin content in staple crop products such as wheat grains. Here, we developed a multi-enzyme extraction method allowing accurate quantification of seven B vitamins in wheat using ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Free forms of thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7) and folates (B9) were determined with recoveries ranging from 81 to 118% and accuracy below 15% bias. The precision was below 20% relative standard deviation and the internal standards adequately compensated for matrix effects. The method was applied to determine the B vitamin stabilities in wheat grains stored at different temperatures and periods. The results provide an important basis in future studies aiming at understanding nutritional availability of B vitamins.

Biotin: a scoping review for Nordic Nutrition Recommendations 2023

Biotin is a water-soluble B-vitamin with key roles in metabolism and are found in most foods at low concentrations. Symptomatic biotin deficiency is rare, and few studies have investigated biotin requirements in relation to health outcomes. Data to support the setting of dietary reference values for biotin are limited.

Comparative bioavailability of vitamins in human foods sourced from animals and plants

Vitamins are essential components of enzyme systems involved in normal growth and function. The quantitative estimation of the proportion of dietary vitamins, that is in a form available for utilization by the human body, is limited and fragmentary. This review provides the current state of knowledge on the bioavailability of thirteen vitamins and choline, to evaluate whether there are differences in vitamin bioavailability when human foods are sourced from animals or plants. The bioavailability of naturally occurring choline, vitamin D, vitamin E, and vitamin K in food awaits further studies. Animal-sourced foods are the almost exclusive natural sources of dietary vitamin B-12 (65% bioavailable) and preformed vitamin A retinol (74% bioavailable), and contain highly bioavailable biotin (89%), folate (67%), niacin (67%), pantothenic acid (80%), riboflavin (61%), thiamin (82%), and vitamin B-6 (83%). Plant-based foods are the main natural sources of vitamin C (76% bioavailable), provitamin A carotenoid β-carotene (15.6% bioavailable), riboflavin (65% bioavailable), thiamin (81% bioavailable), and vitamin K (16.5% bioavailable). The overview of studies showed that in general, vitamins in foods originating from animals are more bioavailable than vitamins in foods sourced from plants.

Brain Trauma and the Secondary Cascade in Humans: Review of the Potential Role of Vitamins in Reparative Processes and Functional Outcome

An estimated sixty-nine million people sustain a traumatic brain injury each year. Trauma to the brain causes the primary insult and initiates a secondary biochemical cascade as part of the immune and reparative response to injury. The secondary cascade, although a normal physiological response, may also contribute to ongoing neuroinflammation, oxidative stress and axonal injury, continuing in some cases years after the initial insult. In this review, we explain some of the biochemical mechanisms of the secondary cascade and their potential deleterious effects on healthy neurons including secondary cell death. The second part of the review focuses on the role of micronutrients to neural mechanisms and their potential reparative effects with regards to the secondary cascade after brain injury. The biochemical response to injury, hypermetabolism and excessive renal clearance of nutrients after injury increases the demand for most vitamins. Currently, most research in the area has shown positive outcomes of vitamin supplementation after brain injury, although predominantly in animal (murine) models. There is a pressing need for more research in this area with human participants because vitamin supplementation post-trauma is a potential cost-effective adjunct to other clinical and therapeutic treatments. Importantly, traumatic brain injury should be considered a lifelong process and better evaluated across the lifespan of individuals who experience brain injury.

Physiological Associations between Vitamin B Deficiency and Diabetic Kidney Disease

The number of people living with chronic kidney disease (CKD) is growing as our global population continues to expand. With aging, diabetes, and cardiovascular disease being major harbingers of kidney disease, the number of people diagnosed with diabetic kidney disease (DKD) has grown concurrently. Poor clinical outcomes in DKD could be influenced by an array of factors-inadequate glycemic control, obesity, metabolic acidosis, anemia, cellular senescence, infection and inflammation, cognitive impairment, reduced physical exercise threshold, and, importantly, malnutrition contributing to protein-energy wasting, sarcopenia, and frailty. Amongst the various causes of malnutrition in DKD, the metabolic mechanisms of vitamin B (B1 (Thiamine), B2 (Riboflavin), B3 (Niacin/Nicotinamide), B5 (Pantothenic Acid), B6 (Pyridoxine), B8 (Biotin), B9 (Folate), and B12 (Cobalamin)) deficiency and its clinical impact has garnered greater scientific interest over the past decade. There remains extensive debate on the biochemical intricacies of vitamin B metabolic pathways and how their deficiencies may affect the development of CKD, diabetes, and subsequently DKD, and vice-versa. Our article provides a review of updated evidence on the biochemical and physiological properties of the vitamin B sub-forms in normal states, and how vitamin B deficiency and defects in their metabolic pathways may influence CKD/DKD pathophysiology, and in reverse how CKD/DKD progression may affect vitamin B metabolism. We hope our article increases awareness of vitamin B deficiency in DKD and the complex physiological associations that exist between vitamin B deficiency, diabetes, and CKD. Further research efforts are needed going forward to address the knowledge gaps on this topic.

Genome-Wide Expression Profiling and Networking Reveals an Imperative Role of IMF-Associated Novel CircRNAs as ceRNA in Pigs

Intramuscular fat (IMF) deposition is a biological process that has a strong impact on the nutritional and sensorial properties of meat, with relevant consequences on human health. Pork loins determine the effects of marbling on the sensory attributes and meat quality properties, which differ among various pig breeds. This study explores the crosstalk of non-coding RNAs with mRNAs and analyzes the potential pathogenic role of IMF-associated competing endogenous RNA (ceRNA) in IMF tissues, which offer a framework for the functional validation of key/potential genes. A high-throughput whole-genome transcriptome analysis of IMF tissues from longissimus dorsi muscles of Large White (D_JN) and Laiwu (L_JN) pigs resulted in the identification of 283 differentially expressed circRNAs (DECs), including two key circRNAs (circRNA-23437, circRNA-08840) with potential binding sites for multiple miRNAs regulating the whole network. The potential ceRNA mechanism identified the DEC target miRNAs-mRNAs involved in lipid metabolism, fat deposition, meat quality, and metabolic syndrome via the circRNA-miRNA-mRNA network, concluding that ssc-mir-370 is the most important target miRNA shared by both key circRNAs. TGM2, SLC5A6, ECI1, FASN, PER1, SLC25A34, SOD1, and COL5A3 were identified as hub genes through an intensive protein-protein interaction (PPI) network analysis of target genes acquired from the ceRNA regulatory network. Functional enrichments, pathway examinations, and qRT-PCR analyses infer their implications in fat/cholesterol metabolism, insulin secretion, and fatty acid biosynthesis. Here, circRNAs and miRNA sequencing accompanied by computational techniques were performed to analyze their expressions in IMF tissues from the longissimus dorsi muscles of two pig breeds. Their target gene evolutionary trajectories, expression profiling, functional enrichments, subcellular localizations, and structural advances with high-throughput protein modeling, following genomic organizations, will provide new insights into the underlying molecular mechanisms of adipocyte differentiation and IMF deposition and a much-needed qualitative framework for future research to improve meat quality and its role as a biomarker to treat lipid metabolic syndromes.

Advances in modular control of CAR-T therapy with adapter-mediated CARs

Protein engineering has contributed to successes in the field of T cell-based immunotherapy, including chimeric antigen receptor (CAR) T cell therapy. CAR T cell therapy has become a pillar of cancer immunotherapy, demonstrating clinical effectiveness against B cell malignancies by targeting the B cell antigen CD19. Current gene editing techniques have limited safety controls over CAR T cell activity, which presents a hurdle for control of CAR T cells in patients. Alternatively, CAR T cell activity can be controlled by engineering CARs to bind soluble adapter molecules that direct the interaction between the CAR T cell and target cell. The flexibility in this adapter-mediated approach overcomes the rigid specificity of traditional CAR T cells to allow targeting of multiple cell types. Here we describe adapter CAR T technologies and how these methods emphasize the growing role of protein engineering in the design of programmable tools for T cell therapies.

ESPEN micronutrient guideline

BACKGROUND

Trace elements and vitamins, named together micronutrients (MNs), are essential for human metabolism. Recent research has shown the importance of MNs in common pathologies, with significant deficiencies impacting the outcome.

OBJECTIVE

This guideline aims to provide information for daily clinical nutrition practice regarding assessment of MN status, monitoring, and prescription. It proposes a consensus terminology, since many words are used imprecisely, resulting in confusion. This is particularly true for the words "deficiency", "repletion", "complement", and "supplement".

METHODS

The expert group attempted to apply the 2015 standard operating procedures (SOP) for ESPEN which focuses on disease. However, this approach could not be applied due to the multiple diseases requiring clinical nutrition resulting in one text for each MN, rather than for diseases. An extensive search of the literature was conducted in the databases Medline, PubMed, Cochrane, Google Scholar, and CINAHL. The search focused on physiological data, historical evidence (published before PubMed release in 1996), and observational and/or randomized trials. For each MN, the main functions, optimal analytical methods, impact of inflammation, potential toxicity, and provision during enteral or parenteral nutrition were addressed. The SOP wording was applied for strength of recommendations.

RESULTS

There was a limited number of interventional trials, preventing meta-analysis and leading to a low level of evidence. The recommendations underwent a consensus process, which resulted in a percentage of agreement (%): strong consensus required of >90% of votes. Altogether the guideline proposes sets of recommendations for 26 MNs, resulting in 170 single recommendations. Critical MNs were identified with deficiencies being present in numerous acute and chronic diseases. Monitoring and management strategies are proposed.

CONCLUSION

This guideline should enable addressing suboptimal and deficient status of a bundle of MNs in at-risk diseases. In particular, it offers practical advice on MN provision and monitoring during nutritional support.

Influence of Endogenous Factors of Food Matrices on Avidin—Biotin Immunoassays for the Detection of Bacitracin and Colistin in Food

(Strept)avidin–biotin technology is frequently used in immunoassay systems to improve their analytical properties. It is known from clinical practice that many (strept)avidin–biotin-based tests provide false results when analyzing patient samples with a high content of endogenous biotin. No specific investigation has been carried out regarding possible interferences from avidin (AVI) and biotin (B₇) contained in food matrices in (strept)avidin–biotin-based immunoanalytical systems for food safety. Two kinds of competitive ELISAs for bacitracin (BT) and colistin (COL) determination in food matrices were developed based on conventional hapten–protein coating conjugates and biotinylated BT and COL bound to immobilized streptavidin (SAV). Coating SAV–B₇–BT and SAV–B₇–COL complexes-based ELISAs provided 2- and 15-times better sensitivity in BT and COL determination, corresponding to 0.6 and 0.3 ng/mL, respectively. Simultaneously with the determination of the main analytes, these kinds of tests were used as competitive assays for the assessment of AVI or B₇ content up to 10 and 1 ng/mL, respectively, in food matrices (egg, infant milk formulas enriched with B₇, chicken and beef liver). Matrix-free experiments with AVI/B₇-enriched solutions showed distortion of the standard curves, indicating that these ingredients interfere with the adequate quantification of analytes. Summarizing the experience of the present study, it is recommended to avoid immunoassays based on avidin–biotin interactions when analyzing biosamples containing these endogenous factors or enriched with B₇.

Revised D-A-CH reference values for the intake of biotin

Purpose

The reference values for biotin intake for Germany, Austria and Switzerland lead back to a report in 2000. Following a timely update process, they were revised in 2020.

Methods

For infants aged 0 to < 4 months, adequate biotin supply via human milk was assumed and in consequence the reference value reflects the amount of biotin delivered by human milk. For infants aged 4 to < 12 months, biotin intake was extrapolated from the reference value for younger infants. Due to missing data on average requirement, the reference values for biotin intake for children, adolescents and adults were derived based on observed intake levels. The reference value for lactating women considered in addition biotin losses via human milk.

Results

The reference value for biotin intake for infants aged 0 to < 4 months was set at 4 µg/day and for infants aged 4 to < 12 months at 6 µg/day. In children and adolescents, the reference values for biotin intake ranged from 20 µg/day in children 1 to < 4 years to 40 µg/day in youths 15 to < 19 years. For adults including pregnant women, 40 µg/day was derived as reference value for biotin intake. For lactating women, this value was set at 45 µg/day.

Conclusions

As deficiency symptoms of biotin do not occur with a usual mixed diet and the average requirement cannot be determined, reference values for an adequate biotin intake for populations from Germany, Austria and Switzerland were derived from biotin intake levels assessed in population-based nutrition surveys.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02756-0.

Biotin interference in routine IDS-iSYS immunoassays for aldosterone, renin, insulin-like growth factor 1, growth hormone and bone alkaline phosphatase

Biotin is increasingly used as dietary supplement. As many immunoassays rely on a binding between biotin and streptavidin, intake of biotin may interfere with laboratory tests, leading to spurious test results. We examined the extent to which levels of aldosterone, renin, insulin-like growth factor 1 (IGF-1), growth hormone (GH) and bone alkaline phosphatase (BAP) were affected by biotin. In an experimental study performed at Aarhus University Hospital, Denmark, patient samples (plasma or serum) were pooled and spiked with biotin in increasing concentrations (0, 20, 50, 100 and 500 ng/mL). All biomarkers were analyzed using Immunodiagnostic Systems (IDS-iSYS) Multi-Discipline Automated System assays. The average bias (%) was calculated, as the difference in concentrations between the sample without biotin (reference) and the samples with increasing concentrations of biotin. Both aldosterone and renin assays showed substantial biotin interference in a dose-dependent manner, with biases up to +3484% for aldosterone and -98% for renin in the highest concentrations of biotin (100-500 ng/mL). IGF-1, GH and BAP results were generally less affected by added biotin and significant bias (>10%) was observed only when the biotin concentration was 100 ng/mL (IGF-1 and GH) or 500 ng/mL (BAP). In conclusion, biotin interfered with the IDS-iSYS immunoassays, particularly for aldosterone and renin. The assays for GH, IGF-1 and BAP were less sensitive and only with high concentrations of biotin.

Nutrition and hair

Healthy hair results from a combination of good generalized health and mindful health care practices. Many nutritional deficiencies lead to poor hair health and include changes to hair structure, texture, and viability. Although the mechanisms by which individual nutrients contribute to hair growth and maintenance have yet to be fully resolved, there are a variety of risk factors that predispose an individual to a nutritional deficiency; age, malnutrition, malabsorption, and medication use are among the most common. A thorough history should be taken in a patient with a hair disturbance to identify risk factors for a nutritional deficiency, which will then guide directed laboratory testing and treatment.

Deleterious side effects of nutritional supplements

Vitamin and mineral supplement consumption is widespread. They are taken for a variety of conditions, including dermatologic disorders. Although consumers often assume these supplements are safe, excessive consumption of supplements may have deleterious effects. Such vitamin supplements include vitamin A, niacin, biotin, vitamin D, and vitamin E, and specific mineral supplements include zinc, copper, and iron. These supplements may have a number of potential adverse effects.

AACC Guidance Document on Biotin Interference in Laboratory Tests

BACKGROUND

Laboratory tests that use streptavidin-biotin binding mechanisms have the potential to be affected by high circulating biotin concentrations, which would produce positive and negative interference in biotinylated competitive and noncompetitive (sandwich) immunoassays, respectively. Consumption of high-dose biotin supplements for cosmetic or health-related reasons has drawn attention to biotin interference in clinical laboratory tests. Case reports and in vivo studies show that ingestion of supplemental biotin can cause clinically significant errors in select biotinylated immunoassays.

CONTENT

This AACC Academy document is intended to provide guidance to laboratorians and clinicians for preventing, identifying, and dealing with biotin interference. In vivo and in vitro spiking studies have demonstrated that biotin concentrations required to cause interference vary by test and by manufacturer. This document includes discussion of biotin's mechanisms for interference in immunoassays, pharmacokinetics, and results of in vitro and in vivo studies and cites examples of assays known to be affected by high biotin concentrations. This document also provides guidance recommendations intended to assist laboratories and clinicians in identifying and addressing biotin interference in laboratory testing.

SUMMARY

The recent increase in the use of high-dose biotin supplements requires laboratorians and clinicians to be mindful of the potential for biotin interference in biotinylated immunoassay-based laboratory tests. Laboratories, clinicians, regulators, and patients should work together to ensure accurate laboratory results. Laboratories have several options for identifying suspected biotin interference in specimens. Alternatively, the relatively fast elimination of biotin allows the potential for rapid follow-up specimen analysis if necessary.

Anticancer activity of new cationic arylthiophenes against hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is the second most common cancer-related death in the world. No effective curative option exists for the treatment of HCC. The available drugs exhibit severe toxic effects and low therapeutic index.

AIM

This work aimed to examine different monocationic arylthiophene derivatives for possible use as chemotherapeutic agents against HCC.

METHODS

The IC₅₀ values for the compounds were determined. The mechanism of cytotoxicity was further investigated using different methods.

RESULTS

Compound 2j proved to retain the highest cytotoxicity in comparison to as a positive control. The selectivity index of compound 2j revealed the safety to normal cells. Moreover, compound 2j was able to inhibit HepG2 cells´ migration and division. The anticancer effect of compound 2j was found to be partially via cell cycle arrest, activation of the tumour suppressor p53 protein, and induction of apoptosis via both intrinsic and extrinsic pathways. Compound 2j has a potential sensitization activity and significantly reduced the IC₅₀ values for the anticancer drugs doxorubicin, cisplatin, and taxol.

CONCLUSION

The tested arylthiophenes showed a potent cytotoxicity against HepG2 cells and were safe to normal cells. The most active compound 2j was found to be able to inhibit cell division and migration and also to induce apoptosis. Compound 2j also proved to have a sensitization effect on standard anticancer drugs.

Biotin Interference in Point of Care HIV Immunoassay

The use of high concentrations of biotin as a dietary supplement to improve hair, skin, and nail quality has increased in the United States over the past few years. High concentrations of biotin have been shown to interfere with some diagnostic assays that use streptavidin–biotin interactions as one of the steps in the assay. The objective of this report is to evaluate potential biotin interference on the analytical and clinical sensitivity of a point of care (POC) antigen–antibody combo HIV-1 assay. We spiked biotin at concentrations ranging from 12.5 to 400 ng/mL into serum and plasma containing HIV-1 subtype B p24 antigen derived from culture supernatant. The p24 antigen was present in the matrices at 30 pg/mL. Fifty microliters of each sample was applied to Alere Determine HIV-1/2 Ag/Ab combo assay strips in duplicate and results were read by eye after 20 to 30 min. Biotin interfered with detection of HIV-1 p24 in serum and plasma. HIV-1 p24 was not detected at 30 pg/mL p24 when biotin was present at 200 ng/mL concentration. Our study demonstrated that elevated levels of biotin in samples may interfere with POC assays. It is important to consider biotin supplements as potential sources of falsely increased or decreased test results, especially in cases wherein supplementation cannot be ruled out.

Simultaneous determination of 49 amino acids, B vitamins, flavonoids, and phenolic acids in commonly consumed vegetables by ultra-performance liquid chromatography-tandem mass spectrometry

A sensitive and reliable method was developed and validated for the simultaneous determination of 49 amino acids, B vitamins, flavonoids, and phenolic acids based on a rapid metabolomic extraction procedure combined with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) in a single chromatographic run and applied in analysis of 26 commonly consumed vegetables. The chromatographic and sample preparation conditions were optimized, given the high diversity of the target analytes. Eight isotope-labeled standards were applied to validate the method in terms of recovery, linearity, matrix effects, precision, and sensitivity. Most recoveries in four vegetable matrices ranged from 65.0% to 105.3% with associated RSDs < 20%. Low LOQs ranged from 0.06 to 17 µg/kg. Linear calibration curves with different ranges were established with R² > 0.993. Among the 26 vegetables, purple cabbage, broccoli, and red lettuce were found to contain the highest concentrations of free amino acids, B vitamins, and phenolic compounds.

Serum Level of Biotin Rather than the Daily Dosage Is the Main Determinant of Interference on Thyroid Function Assays

INTRODUCTION

Several case reports stress that high-dose biotin causes incorrect laboratory results. However, the extent of this interference in children is not systematically studied.

AIM

To assess factors associated with biotin interference on thyroid function tests in subjects with biotinidase deficiency.

METHOD

The study included 44 children who were treated with oral biotin (Group 1, median dose: 10 mg/day [25-75p; 10-10], age: 1.83 years [1.04-2.90]) and 30 healthy subjects (Group 2, age: 1.05 years [0.37-3.37]). Thyroid function tests were performed with two different assays, and streptavidin-coated particles were used in order to remove biotin from serum samples of cases with biotin interference.

RESULTS

The measurements were first performed with Beckman Coulter. In Group 1, remarkably high levels of fT3 and fT4 were found in 26 (59.1%) and 25 (56.8%) patients, respectively. Thyroid hormone functions were all normal in Group 2. Significantly higher serum biotin levels were detected in interference-positive children (p < 0.001). The serum biotin levels in Group 1 showed a strong positive correlation with fT3 (r = 0.867, p < 0.001) and fT4 levels (r = 0.905, p < 0.001). A serum biotin level of 80.35 µg/L was found to be the best cut-off value for predicting interference (sensitivity: 96.2% and specificity: 94.4%). When analyzed with Siemens Advia Centaur XP, all thyroid function tests were normal in both groups except in one patient (2.27%) with slightly elevated fT3 level in Group 1. Repeated tests with Beckman Coulter after neutralization of biotin with streptavidin magnetic particles in serum samples of the interference-positive cases revealed normal thyroid hormone levels.

CONCLUSION

Interference is an important problem in thyroid function tests in nearly 60% of all children receiving biotin treatment for biotinidase deficiency. Serum levels of biotin rather than the dosage are the main determinant of interference, which can be eliminated by choosing appropriate laboratory methods.

Biotin interference: evaluation of a new generation of electrochemiluminescent immunoassays for high-sensitive troponin T and thyroid-stimulating hormone testing

Background

Biotin is currently a matter of concern for laboratories using biotin-streptavidin-based immunoassays. Biotin interferences have been reported for high-sensitive troponin T (hsTnT) and thyroid-stimulating hormone (TSH) assays. We aimed to evaluate the new generation of hsTnT and TSH electrochemiluminescent immunoassays announced to be less sensitive to biotin.

Methods

Firstly, we assessed the analytical performances of new generation assays (imprecision, bias, total error, limit of quantification) and compared previous and new generation assays in the absence of biotin. Secondly, we challenged both generations of assays with samples spiked with seven different biotin levels. The efficiency of new generation assays was also compared to the streptavidin beads treatment.

Results

New generation assays presented suitable analytical performances. Previous and new generations of hsTnT and TSH assays were commutable in the absence of biotin. In the presence of biotin, we confirmed that previous generation assays were affected by biotin concentration as low as 40.5 ng/mL and that new generation assays were not affected up to the announced tolerance threshold of 1200 ng/mL. After the streptavidin beads treatment, we observed a higher imprecision for both parameters and a constant 10% negative bias for TSH compared to new generation assays.

Conclusions

New generation of electrochemiluminescent immunoassays appears as a reliable systematic solution to prevent biotin interference for hsTnT and TSH testing.

Mitigating biotin interference in two Roche immunoassays by premixing biotinylated capturing molecules with streptavidin coated beads

BACKGROUND

Biotin is an interference in many streptavidin-biotin based immunoassays, causing falsely decreased results with sandwich immunoassays and falsely increased results with competitive immunoassays. It has been discussed that premixing streptavidin coated beads and biotinylated capturing molecules may prevent biotin interference. This study was designed to test whether such modification could mitigate biotin interference in two originally susceptible sandwich immunoassays.

METHODS

Roche C-peptide and human growth hormone (hGH) immunoassays utilize three reagent containers for streptavidin coated beads (M), biotinylated capturing antibody (R1) and ruthenylated antibody (R2). The reagents were modified by premixing reagent M and R1. Following incubation, the beads were placed back in the M-container and R1-supernatant back to R1-container. Patient specimens were selected, spiked with biotin to 1055 ng/mL, and measured by both the original, unmodified reagent and modified reagent on Roche cobas e411 analyzer. The biotin interference dose response curves were also compared using pooled patient specimen spiked with different concentrations of biotin.

RESULTS

For the original reagent, 1055 ng/mL of biotin decreased C- peptide results by 88% and hGH results by 97%. After reagent modification, this interference effect was nearly eliminated for C- peptide but remained about 20% decreased for hGH.

CONCLUSION

Premixing streptavidin beads and biotinylated capturing molecules is an effective approach to mitigate biotin interference for certain immunoassays.

Serum biotin and zinc in male androgenetic alopecia

BACKGROUND

Male androgenetic alopecia (MAGA) is caused by the conversion of the terminal to vellus hair. Zinc is one of the most studied trace elements in hair disorders and biotin is one of the most prescribed supplement for its treatment.

OBJECTIVES

The study aimed to evaluate serum zinc and biotin levels in MAGA patients to answer the question if there is a value to add zinc or biotin as a supplements in the MAGA treatment.

PATIENTS AND METHODS

Sixty MAGA patients and 60 age, sex, and body mass index-matched healthy volunteers were included. We measured serum biotin and zinc in all participants.

RESULTS

Zinc (µg/dL) was lower significantly in patients compared to controls (P = 0.01), suboptimal biotin (ng/L) levels were in patients, and within normal values in controls (P = 0.01). A positive significant correlation was found between serum zinc and serum biotin (r = 0.489, P = 0.001). Serum zinc and biotin showed a nonsignificant correlation with age and disease duration. A non-significant relation was obtained between the MAGA grades, and zinc (P = 0.485) and biotin levels (P = 0.367).

CONCLUSIONS

Serum zinc showed subnormal value and adding zinc supplement in MAGA treatment is recommended. Serum biotin showed a suboptimal level in MAGA patients that is not correlated with patients' age or disease severity. Biotin supplement in MAGA treatment may add value to hair quality and texture. We recommend future biotin evaluation in serum combined with its metabolites in MAGA patients' urine.

Influence of amide versus ester linkages on the anticancer properties of the new flavone-biotin conjugates

Novel biotinylated C-6 substituted flavones were synthesised by a one-step method that connects biotin to 6-hydroxyflavone and 6-aminoflavone by esterification and amidation of hydroxyl and amino groups, respectively. The obtained compounds, 6-O-biotinylflavone and 6-biotinylamidoflavone, are the bifunctional molecules composed of a flavone moiety as a fluorescent reporter and biotin as a cancer-targeting unit. Antiproliferative activity was evaluated using SRB assays in MCF-7, MCF-10A, HepG2, MDA-MB-231, 4T1, and Balb/3T3 cell lines. In vitro evaluation revealed that compounds with biotin moiety displayed better cell selectivity between the cancer and normal cells than the parental substrates. These results indicate that anticancer effect is not related to the position of biotin moiety, but it is related to the presence of ester or amide bond. 6-O-Biotinylflavone was more active than 6-hydroxyflavone against human breast (MDA-MB-231) and liver (HepG2) cancer cells with IC50 (concentration of tested agent that inhibits proliferation of the cell population by 50%) values equal to 78.5 ± 18.8 μM and 133.2 ± 14.2 μM, respectively. Non biotinylated 6-aminoflavone was more active than 6-biotinylamidoflavone against all tested cell lines, with IC50 values between 34.3 ± 9.1 μM (4T1) and 173.86 ± 24.3 μM (MCF-7).

Interpretation of common endocrine laboratory tests: technical pitfalls, their mechanisms and practical considerations

Pitfalls in hormonal assays are commonly seen in clinical practice and may lead to erroneous clinical impressions and treatments. In this article, we address common laboratory pitfalls encountered during evaluation of patients with real or presumed endocrine disorders including high dose hook effect and falsely normal prolactin in cases of macroprolactinomas, macroprolactinemia and falsely elevated prolactin, macrothyrotropinemia and falsely elevated TSH, heterophile antibodies leading to false elevation of hormonal concentration, biotin interference with different hormonal assays, cross-reactivity of steroid hormones immunoassays, and others. We describe the mechanisms of such laboratory pitfalls, review clinical scenarios in which they might occur, and discuss the ways to resolve such conundrums. The aim of this article is to present a learning material for the endocrine trainees and practitioners.

How Biotin Induces Misleading Results in Thyroid Bioassays: Case Series

Biotin is widely available over the counter in different doses and is used medically in the management of hair and nail problems. Recent literature suggested the use of high doses of biotin for the treatment of progressive multiple sclerosis. We present four cases that show a misleading increase in thyroid function tests toward a false diagnosis of Grave's disease after the administration of 20-30 mg biotin for different periods. All the four cases are free of the signs and symptoms of hyperthyroidism, and all of their results returned to baseline values within 24-48 hours after biotin withdrawal. The assemblage of these cases, thyroid assay results, and biotin doses had occurred by chance, with no selection bias, and they represented all cases of biotin interference with thyroid assays in our center during this year. The first case is a 23-year-old female who was diagnosed with Grave's disease during a routine checkup after she ingested a prescribed 20 mg biotin per day for three months for excessive hair fall. The second case is a 19-year-old female with hair and nail problems associated with iron deficiency anemia. She administered a self-prescribed biotin dose of 20 mg a day for a month. She asked an endocrinologist's opinion about a recent increase in her thyroid function tests, with no signs of hyperthyroidism. The third case is a 45-year-old man with near-total thyroidectomy for retrosternal multinodular goiter with compressive symptoms. His usual levothyroxine dose had been decreased from 100 to 50 microgram per day, after which he felt unwell and gained four kilograms, with signs and symptoms of hypothyroidism. His investigations were consistent with hyperthyroidism while his signs were of hypothyroidism, which was illogical. He was administered 30 mg medically prescribed biotin for nail changes due to recently diagnosed psoriasis. The fourth case is that of one of the authors who volunteered to take 30 mg of biotin daily for one week. His initial investigations were in the normal range but changed within this period to be Grave's disease-like, with no signs or symptoms. In conclusion, the ingestion of 20 mg or more of biotin may lead to a clinically relevant thyroid assay interference. The clinicians must take this point in consideration before assessing the results of any thyroid function tests.

Insignificant interference of Elevit in pregnant women serum samples with HBsAg immunoassay on Sysmex

BACKGROUND

The pregnant women often take Elevit as the multivitamin supplement which has a substantial amount of biotin that might potentially interfere with the HBsAg immunoassay performed by the prevalent Sysmex system in clinical laboratories. We therefore wanted to determine this, so that the therapeutic intervention on the hepatitis B virus infection during pregnancy and birth would not be missed.

METHODS

Elevit was both serially diluted in vitro and orally taken by healthy volunteers whose blood samples were then taken at different time points. All samples were added to a serum sample with a known result of HBsAg and then measured by Sysmex. The Abbott immunoassay system was used as the control as it involves no streptavidin-biotin binding in the reagent set. Besides, the HBsAg results were compared between the pregnant women taking or not taking Elevit.

RESULTS

Biotin at 25 ng/mL in the Elevit started to suppress the HBsAg and reached about 50% suppression at 100 ng/mL on Sysmex. In the volunteers, biotin reached the peak concentration at 2 hours. However, their blood samples showed no suppression on the HBsAg detection by Sysmex. In samples from pregnant women who took Elevit, the HBsAg results by Sysmex were highly correlated with those by Abbott (R²  = 0.96). Comparison of the results from Sysmex between the age- and pregnancy-matched females with and without Elevit intake showed no difference.

CONCLUSION

Elevit intake in pregnant women shows no significant interference with HBsAg immunoassay on Sysmex.

Biotin Deficiency Induces Th1- and Th17-Mediated Proinflammatory Responses in Human CD4+ T Lymphocytes via Activation of the mTOR Signaling Pathway

Biotin (vitamin B7) is essential for human health because of its involvement, as a cofactor, in a variety of critical cellular metabolic reactions. Previous studies have shown that biotin deficiency enhances inflammation, and certain chronic inflammatory diseases are associated with biotin deficiency; however, the mechanisms that mediate the association between biotin status and inflammation are not well understood. In this study, we examined the effect of biotin deficiency on human CD4+ T cell responses to determine their role in biotin deficiency-associated inflammation. Our investigations revealed that anti-CD3/CD28-stimulated CD4+ T cells cultured in biotin-deficient medium secreted significantly enhanced levels of the proinflammatory cytokines IFN-γ, TNF, and IL-17. Expression of the transcription factors T-bet and RORγt was increased, whereas Foxp3 expression was decreased, in biotin-deficient CD4+ T cells. The percentage of T regulatory cells was also decreased under biotin-deficient condition. A similar increase in T-bet, RORγt, and proinflammatory cytokine levels, as well as a decrease in Foxp3, was observed in inguinal lymph nodes of mice fed a biotin-deficient diet relative to pair-fed controls. Furthermore, differentiation of CD4+ T cells toward Th1 and Th17 cells was also enhanced. In vitro and in vivo investigations indicated that the increased inflammatory response was due to enhanced activation of the mammalian target of rapamycin signaling pathway in biotin-deficient CD4+ T cells. In summary, these results demonstrate that biotin deficiency enhances the inflammatory responses in CD4+ T cells, which may contribute to inflammation associated with biotin deficiency.

BIOTIN INTERFERENCE WITH ROUTINE CLINICAL IMMUNOASSAYS: UNDERSTAND THE CAUSES AND MITIGATE THE RISKS

OBJECTIVE

The objectives of this report are to review the mechanisms of biotin interference with streptavidin/biotin-based immunoassays, identify automated immunoassay systems vulnerable to biotin interference, describe how to estimate and minimize the risk of biotin interference in vulnerable assays, and review the literature pertaining to biotin interference in endocrine function tests.

METHODS

The data in the manufacturer's "Instructions for Use" for each of the methods utilized by seven immunoassay system were evaluated. We also conducted a systematic search of PubMed/MEDLINE for articles containing terms associated with biotin interference. Available original reports and case series were reviewed. Abstracts from recent scientific meetings were also identified and reviewed.

RESULTS

The recent, marked, increase in the use of over-the-counter, high-dose biotin supplements has been accompanied by a steady increase in the number of reports of analytical interference by exogenous biotin in the immunoassays used to evaluate endocrine function. Since immunoassay methods of similar design are also used for the diagnosis and management of anemia, malignancies, autoimmune and infectious diseases, cardiac damage, etc., biotin-related analytical interference is a problem that touches every area of internal medicine.

CONCLUSION

It is important for healthcare personnel to become more aware of immunoassay methods that are vulnerable to biotin interference and to consider biotin supplements as potential sources of falsely increased or decreased test results, especially in cases where a lab result does not correlate with the clinical scenario.

ABBREVIATIONS

FDA = U.S. Food & Drug Administration FT3 = free tri-iodothyronine FT4 = free thyroxine IFUs = instructions for use LH = luteinizing hormone PTH = parathyroid hormone SA/B = streptavidin/biotin TFT = thyroid function test TSH = thyroid-stimulating hormone.

A Review of the Use of Biotin for Hair Loss

BACKGROUND

Biotin has gained commercial popularity for its claimed benefits on healthy hair and nail growth. Despite its reputation, there is limited research to support the utility of biotin in healthy individuals.

OBJECTIVE

To systematically review the literature on biotin efficacy in hair and nail growth.

METHODS

We conducted a PubMed search of all case reports and randomized clinical trials (RCTs) using the following terms: (biotin and hair); (biotin and supplementation and hair); (biotin supplementation); (biotin and alopecia); (biotin and nails); (biotin and dermatology), and (biotin recommendations).

RESULTS

We found 18 reported cases of biotin use for hair and nail changes. In all cases, patients receiving biotin supplementation had an underlying pathology for poor hair or nail growth. All cases showed evidence of clinical improvement after receiving biotin.

CONCLUSIONS

Though its use as a hair and nail growth supplement is prevalent, research demonstrating the efficacy of biotin is limited. In cases of acquired and inherited causes of biotin deficiency as well as pathologies, such as brittle nail syndrome or uncombable hair, biotin supplementation may be of benefit. However, we propose these cases are uncommon and that there is lack of sufficient evidence for supplementation in healthy individuals.

Selective accumulation of biotin in arterial chemoreceptors: requirement for carotid body exocytotic dopamine secretion

KEY POINTS

Biotin, a vitamin whose main role is as a coenzyme for carboxylases, accumulates at unusually large amounts within cells of the carotid body (CB). In biotin-deficient rats biotin rapidly disappears from the blood; however, it remains at relatively high levels in CB glomus cells. The CB contains high levels of mRNA for SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin. Animals with biotin deficiency exhibit pronounced metabolic lactic acidosis. Remarkably, glomus cells from these animals have normal electrical and neurochemical properties. However, they show a marked decrease in the size of quantal dopaminergic secretory events. Inhibitors of the vesicular monoamine transporter 2 (VMAT2) mimic the effect of biotin deficiency. In biotin-deficient animals, VMAT2 protein expression decreases in parallel with biotin depletion in CB cells. These data suggest that dopamine transport and/or storage in small secretory granules in glomus cells depend on biotin.

ABSTRACT

Biotin is a water-soluble vitamin required for the function of carboxylases as well as for the regulation of gene expression. Here, we report that biotin accumulates in unusually large amounts in cells of arterial chemoreceptors, carotid body (CB) and adrenal medulla (AM). We show in a biotin-deficient rat model that the vitamin rapidly disappears from the blood and other tissues (including the AM), while remaining at relatively high levels in the CB. We have also observed that, in comparison with other peripheral neural tissues, CB cells contain high levels of SLC5a6, a biotin transporter, and SLC19a3, a thiamine transporter regulated by biotin. Biotin-deficient rats show a syndrome characterized by marked weight loss, metabolic lactic acidosis, aciduria and accelerated breathing with normal responsiveness to hypoxia. Remarkably, CB cells from biotin-deficient animals have normal electrophysiological and neurochemical (ATP levels and catecholamine synthesis) properties; however, they exhibit a marked decrease in the size of quantal catecholaminergic secretory events, which is not seen in AM cells. A similar differential secretory dysfunction is observed in CB cells treated with tetrabenazine, a selective inhibitor of the vesicular monoamine transporter 2 (VMAT2). VMAT2 is highly expressed in glomus cells (in comparison with VMAT1), and in biotin-deficient animals VMAT2 protein expression decreases in parallel with the decrease of biotin accumulated in CB cells. These data suggest that biotin has an essential role in the homeostasis of dopaminergic transmission modulating the transport and/or storage of transmitters within small secretory granules in glomus cells.

Biochemical Hyperthyroidism in a Newborn Baby Caused by Assay Interaction from Biotin Intake

We describe a case of biochemical neonatal thyrotoxicosis caused by biotin supplementation. Biotin may interact with thyroid function testing to imitate thyrotoxicosis with low thyroid-stimulating hormone and elevated triiodothyronine and thyroxine levels.

Biotinidase deficiency: Spectrum of molecular, enzymatic and clinical information from newborn screening Ontario, Canada (2007-2014)

Untreated profound biotinidase deficiency results in a wide range of clinical features, including optic atrophy, cutaneous abnormalities, hearing loss and developmental delay. Ontario, Canada incorporated this treatable deficiency in newborn screening over the past 8years. This study elucidates the molecular, biochemical, and clinical findings from the pilot project. Information from initial screens, serum biotinidase activity level assays, molecular testing, and family history for 246 positive newborns screens were analyzed. A mutation spectrum was created for the province of Ontario, including common mutations such as D444H, D444H/A171T, Q456H, C33fs, and R157H. Individuals with partial deficiency were separated into 3 groups: D444H homozygotes (Group 1); compound heterozygotes for D444H with another profound allele (Group 2); compound heterozygotes with two non-D444H alleles (Group 3). Biochemical phenotype-genotype associations in partial deficiency showed a significant difference in serum biotinidase activity in between any given two groups. Three children with partial deficiency discontinued biotin for varied lengths of time. Two of whom became symptomatic with abnormal gait, alopecia, skin rashes and developmental delay. A need for more congruency in diagnostic, treatment and educational practices was highlighted across the province. Heterogeneity and variation in clinical presentations and management was observed in patients with the partial deficiency.

The sodium/multivitamin transporter: a multipotent system with therapeutic implications

The Na(+)/multivitamin transporter (SMVT) is a member of the solute:sodium symporter family that catalyzes the Na(+)-dependent uptake of the structurally diverse water-soluble vitamins pantothenic acid (vitamin B5) and biotin (vitamin H), α-lipoic acid-a vitamin-like substance with strong antioxidant properties-and iodide. The organic substrates of SMVT play central roles in the cellular metabolism and are, therefore, essential for normal human health and development. For example, biotin deficiency leads to growth retardation, dermatological disorders, and neurological disorders. Animal studies have shown that biotin deficiency during pregnancy is directly correlated to embryonic growth retardation, congenital malformation, and death of the embryo. This chapter focuses on the structural and functional features of the human isoform of SMVT (hSMVT); the discovery of which was greatly facilitated by the cloning and expression of hSMVT in tractable expression systems. Special emphasis will be given to mechanistic implications of the transport process of hSMVT that will inform our understanding of the molecular determinants of hSMVT-mediated transport in dynamic context to alleviate the development and optimization of hSMVT as a multipotent platform for drug delivery.

Anticancer, antioxidant activities, and DNA affinity of novel monocationic bithiophenes and analogues

A series of 15 monocationic bithiophenes and isosteres were prepared and subjected to in vitro antiproliferative screening using the full National Cancer Institute (NCI)-60 cell line panel, representing nine types of cancer. Among the nine types of cancer involved in a five-dose screen, non-small cell lung and breast cancer cell lines were the most responsive to the antiproliferative effect of the tested compounds, especially cell lines A549/ATCC, NCI-H322M, and NCI-H460, whereas compounds 1a, 1c, 1d, and 7 exhibited potent activity, with GI50 values (drug concentration that causes 50% inhibition of cell growth) from less than 10 nM to 102 nM. In addition, compounds 1c and 1d gave GI50 values of 73 nM and 79 nM, respectively, against the MDA-MB-468 breast cancer cell line. Structure-activity relationship findings indicated that the mononitriles were far less active than their corresponding monoamidines and, within the amidines series, the bioisosteric replacement of a thiophene ring by a furan led to a reduction in antiproliferative activity. Also, molecular manipulations, involving substitution on the phenyl ring, or its replacement by a pyridyl, or alteration of the position of the amidine group, led to significant alteration in antiproliferative activity. On the other hand, DNA studies demonstrated that these monoamidine bichalcophenes have promising ability to cleave the genomic DNA. These monoamidines show a wide range of DNA affinities, as judged from their DNA cleavage effect, which are remarkably sensitive to all kinds of structural modifications. Finally, the novel bichalcophenes were tested for their antioxidant property by the ABTS (2,2'-azino- bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt) assay, as well as lipid and nitric oxide scavenging techniques, and were found to exhibit good-to-potent antioxidant abilities.

Biotin-triggered release and transfection of DNA complexes immobilized on a substrate via biotin–avidin interaction

In this study, the highly specific biotin–avidin interaction was used to immobilize DNA complexes to a substrate. An excess of biotin was added to trigger the dissociation of DNA complexes from the substrate to mediate their release and transfection. Biotin-grafted-polyethyleneimine/DNA complexes with N/P ratio of 5 were prepared with diameter of 170.2 nm and ζ-potential of 16.1 mV. The DNA immobilized substrates were fabricated using a biotin–avidin–biotin sandwich model, which were characterized by atom force microscope and fluorescent microscope. Compared to DNA immobilization by physical adsorption, a higher DNA density of 935 ng/cm2 was observed on biotinylated substrates. Based on the in vitro release profiles, the DNA complexes immobilized on silanized substrate released faster than those on biotinylated substrate. Triggered by the addition of extra biotin, more DNA complexes were released. The transfection efficiencies of the DNA complexes immobilized on different substrates were assayed on HEK-293T cells. The highest transfection efficiency was obtained in the group of biotinylated substrate with the trigger of extra biotin. Thus, the system of demobilized DNA complexes onto a substrate by the biotin–avidin interaction and the dissociation of DNA complexes from a substrate triggered by the extra biotin provides a promising strategy for the realization of the controlled release and enhanced transgene expression of genes.