Riboflavin status in acute ischaemic stroke

Effects of riboflavin in the treatment of brain damage caused by oxygen deprivation: an integrative systematic review

Brain oxygen deprivation causes morphological damage involved in the formation of serious pathological conditions such as stroke and cerebral palsy. Therapeutic methods for post-hypoxia/anoxia injuries are limited and still have deficiencies in terms of safety and efficacy. Recently, clinical studies of stroke have reported the use of drugs containing riboflavin for post-injury clinical rehabilitation, however, the effects of vitamin B2 on exposure to cerebral oxygen deprivation are not completely elucidated. This review aimed to investigate the potential antioxidant, anti-inflammatory and neuroprotective effects of riboflavin in cerebral hypoxia/anoxia. After a systematic search, 21 articles were selected, 8 preclinical and 12 clinical studies, and 1 translational study. Most preclinical studies used B2 alone in models of hypoxia in rodents, with doses of 1-20 mg/kg (in vivo) and 0.5-5 µM (in vitro). Together, these works suggested greater regulation of lipid peroxidation and apoptosis and an increase in neurotrophins, locomotion, and cognition after treatment. In contrast, several human studies have administered riboflavin (5 mg) in combination with other Krebs cycle metabolites, except one study, which used only B2 (20 mg). A reduction in lactic acidosis and recovery of sensorimotor functions was observed in children after treatment with B2, while adults and the elderly showed a reduction in infarct volume and cognitive rehabilitation. Based on findings from preclinical and clinical studies, we conclude that the use of riboflavin alone or in combination acts beneficially in correcting the underlying brain damage caused by hypoxia/anoxia and its inflammatory, oxidative, and behavioral impairments.

Nutritional therapy for reducing disability and improving activities of daily living in people after stroke

BACKGROUND

Stroke patients often face disabilities that significantly interfere with their daily lives. Poor nutritional status is a common issue amongst these patients, and malnutrition can severely impact their functional recovery post-stroke. Therefore, nutritional therapy is crucial in managing stroke outcomes. However, its effects on disability, activities of daily living (ADL), and other critical outcomes have not been fully explored.

OBJECTIVES

To evaluate the effects of nutritional therapy on reducing disability and improving ADL in patients after stroke.

SEARCH METHODS

We searched the trial registers of the Cochrane Stroke Group, CENTRAL, MEDLINE (from 1946), Embase (from 1974), CINAHL (from 1982), and AMED (from 1985) to 19 February 2024. We also searched trials and research registries (ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform) and reference lists of articles.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared nutritional therapy with placebo, usual care, or one type of nutritional therapy in people after stroke. Nutritional therapy was defined as the administration of supplemental nutrients, including energy, protein, amino acids, fatty acids, vitamins, and minerals, through oral, enteral, or parenteral methods. As a comparator, one type of nutritional therapy refers to all forms of nutritional therapies, excluding the specific nutritional therapy defined for use in the intervention group.

DATA COLLECTION AND ANALYSIS

We used Cochrane's Screen4Me workflow to assess the initial search results. Two review authors independently screened references that met the inclusion criteria, extracted data, and assessed the risk of bias and the certainty of the evidence using the GRADE approach. We calculated the mean difference (MD) or standardised mean difference (SMD) for continuous data and the odds ratio (OR) for dichotomous data, with 95% confidence intervals (CIs). We assessed heterogeneity using the I2 statistic. The primary outcomes were disability and ADL. We also assessed gait, nutritional status, all-cause mortality, quality of life, hand and leg muscle strength, cognitive function, physical performance, stroke recurrence, swallowing function, neurological impairment, and the development of complications (adverse events) as secondary outcomes.

MAIN RESULTS

We identified 52 eligible RCTs involving 11,926 participants. Thirty-six studies were conducted in the acute phase, 10 in the subacute phase, three in the acute and subacute phases, and three in the chronic phase. Twenty-three studies included patients with ischaemic stroke, three included patients with haemorrhagic stroke, three included patients with subarachnoid haemorrhage (SAH), and 23 included patients with ischaemic or haemorrhagic stroke including SAH. There were 25 types of nutritional supplements used as an intervention. The number of studies that assessed disability and ADL as outcomes were nine and 17, respectively. For the intervention using oral energy and protein supplements, which was a primary intervention in this review, six studies were included. The results for the seven outcomes focused on (disability, ADL, body weight change, all-cause mortality, gait speed, quality of life, and incidence of complications (adverse events)) were as follows: There was no evidence of a difference in reducing disability when 'good status' was defined as an mRS score of 0 to 2 (for 'good status': OR 0.97, 95% CI 0.86 to 1.10; 1 RCT, 4023 participants; low-certainty evidence). Oral energy and protein supplements may improve ADL as indicated by an increase in the FIM motor score, but the evidence is very uncertain (MD 8.74, 95% CI 5.93 to 11.54; 2 RCTs, 165 participants; very low-certainty evidence). Oral energy and protein supplements may increase body weight, but the evidence is very uncertain (MD 0.90, 95% CI 0.23 to 1.58; 3 RCTs, 205 participants; very low-certainty evidence). There was no evidence of a difference in reducing all-cause mortality (OR 0.57, 95% CI 0.14 to 2.28; 2 RCTs, 4065 participants; low-certainty evidence). For gait speed and quality of life, no study was identified. With regard to incidence of complications (adverse events), there was no evidence of a difference in the incidence of infections, including pneumonia, urinary tract infections, and septicaemia (OR 0.68, 95% CI 0.20 to 2.30; 1 RCT, 42 participants; very low-certainty evidence). The intervention was associated with an increased incidence of diarrhoea compared to usual care (OR 4.29, 95% CI 1.98 to 9.28; 1 RCT, 4023 participants; low-certainty evidence) and the occurrence of hyperglycaemia or hypoglycaemia (OR 15.6, 95% CI 4.84 to 50.23; 1 RCT, 4023 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

We are uncertain about the effect of nutritional therapy, including oral energy and protein supplements and other supplements identified in this review, on reducing disability and improving ADL in people after stroke. Various nutritional interventions were assessed for the outcomes in the included studies, and almost all studies had small sample sizes. This led to challenges in conducting meta-analyses and reduced the precision of the evidence. Moreover, most of the studies had issues with the risk of bias, especially in terms of the absence of blinding and unclear information. Regarding adverse events, the intervention with oral energy and protein supplements was associated with a higher number of adverse events, such as diarrhoea, hyperglycaemia, and hypoglycaemia, compared to usual care. However, the quality of the evidence was low. Given the low certainty of most of the evidence in our review, further research is needed. Future research should focus on targeted nutritional interventions to reduce disability and improve ADL based on a theoretical rationale in people after stroke and there is a need for improved methodology and reporting.

Plasma riboflavin fluorescence as a diagnostic marker of mesenteric ischemia-reperfusion injury in rats

Due to the delayed and vague symptoms, it is difficult to early diagnose mesenteric ischemia injuries in the dynamics of acute illness, leading to a 60-80 % mortality rate. Here, we found plasma fluorescence spectra can rapidly assess the severity of mesenteric ischemia injury in animal models. Ischemia-reperfusion damage of the intestine leads to multiple times increase in NADH, flavins, and porphyrin auto-fluorescence of blood. The fluorescence intensity ratio between blue-fluorophores and flavins can reflect the occurrence of shock. Using liquid chromatography and mass spectroscopy, we confirm that riboflavin is primarily responsible for the increased flavin fluorescence. Since humans absorb riboflavin from the intestine, its increase in plasma may indicate intestinal mucosa injury. Our work suggests a self-calibrated and reagent-free approach to identifying the emergence of fatal mesenteric ischemia in emergency departments or intensive care units.

Micro-SPECT Imaging of Acute Ischemic Stroke with Radioiodinated Riboflavin in Rat MCAO Models via Riboflavin Transporter Targeting

Riboflavin transporter-3 (RFVT3) is a recently discovered and novel biomarker for the theranostics of nervous system diseases. RFVT3 is significantly overexpressed in cerebral injury after ischemic stroke. Herein, we first reported an RFVT3-targeted tracer ¹³¹I-riboflavin (¹³¹I-RFLA) for SPECT imaging of ischemic stroke in vivo. ¹³¹I-RFLA was radiosynthesized by the iodogen-coating method. ¹³¹I-RFLA possessed a radiochemical yield of 69.2 ± 3.7% and greater than 95% radiochemical purity. The representative SPECT/CT images using ¹³¹I-RFLA demonstrated the conspicuously increased tracer uptake in the cerebral injury by comparison with the contralateral normal brain at 1 h and 3 and 7 d after stroke. Ex vivo autoradiography demonstrated that the ratio of infarcted to normal brain uptake was 3.63 and it was decreased to 1.98 after blocking, which reconfirmed the results of SPECT images. Importantly, a significant correlation was identified between RFVT3 expression and brain injury by H&E and immunohistochemistry staining. Therefore, RFVT3 is a new and potential biomarker for the early diagnosis of ischemic stroke. In addition, ¹³¹I-RFLA is a promising SPECT tracer for imaging RFVT3-related ischemic cerebral injury in vivo.

Riboflavin in Neurological Diseases: A Narrative Review

Riboflavin is classified as one of the water-soluble B vitamins. It is part of the functional group of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) cofactors and is required for numerous flavoprotein-catalysed reactions. Riboflavin has important antioxidant properties, essential for correct cell functioning. It is required for the conversion of oxidised glutathione to the reduced form and for the mitochondrial respiratory chain as complexes I and II contain flavoprotein reductases and electron transferring flavoproteins. Riboflavin deficiency has been demonstrated to impair the oxidative state of the body, especially in relation to lipid peroxidation status, in both animal and human studies. In the nervous system, riboflavin is essential for the synthesis of myelin and its deficiency can determine the disruption of myelin lamellae. The inherited condition of restricted riboflavin absorption and utilisation, reported in about 10-15% of world population, warrants further investigation in relation to its association with the main neurodegenerative diseases. Several successful trials testing riboflavin for migraine prevention were performed, and this drug is currently classified as a Level B medication for migraine according to the American Academy of Neurology evidence-based rating, with evidence supporting its efficacy. Brown-Vialetto-Van Laere syndrome and Fazio-Londe diseases are now renamed as "riboflavin transporter deficiency" because these are autosomal recessive diseases caused by mutations of SLC52A2 and SLC52A3 genes that encode riboflavin transporters. High doses of riboflavin represent the mainstay of the therapy of these diseases and high doses of riboflavin should be rapidly started as soon as the diagnosis is suspected and continued lifelong. Remarkably, some mitochondrial diseases respond to supplementation with riboflavin. These include multiple acyl-CoA-dehydrogenase deficiency (which is caused by ETFDH gene mutations in the majority of the cases, or mutations in the ETFA and ETFB genes in a minority), mutations of ACAD9 gene, mutations of AIFM1 gene, mutations of the NDUFV1 and NDUFV2 genes. Therapeutic riboflavin administration has been tried in other neurological diseases, including stroke, multiple sclerosis, Friedreich's ataxia and Parkinson's disease. Unfortunately, the design of these clinical trials was not uniform, not allowing to accurately assess the real effects of this molecule on the disease course. In this review we analyse the properties of riboflavin and its possible effects on the pathogenesis of different neurological diseases, and we will review the current indications of this vitamin as a therapeutic intervention in neurology.

Proteomics and metabolomics of raw rhubarb and wine-processed rhubarb in the treatment of rats with intracerebral hemorrhage

Background

To explore the mechanisms of raw rhubarb and wine-processed rhubarb treatment in a rat model of intracerebral hemorrhage (ICH).

Methods

After adapting to their environment, 30 male Wistar rats were divided into 5 treatment groups: blank control group (CK) (normal saline), sham operation group (SICH) (normal saline), ICH model group (ICH) (normal saline), ICH + raw rhubarb enema group (RO) (raw rhubarb 3.60 g/kg), and ICH + wine-processed rhubarb enema group (WRO) (wine-processed rhubarb 3.60 g/kg). The rhubarb enema (once a day) was given since 3 days before ICH treatment, and was consistently given until 12 hours, 24 hours, 3 days, and 7 days post operation. Serum oxidative stress and inflammatory markers were detected by ELISA, and differences between raw rhubarb and wine-processed rhubarb treatment in ICH rats were screened by proteomics and metabolomics.

Results

Both rhubarb treatments effectively improved oxidative stress and inflammatory responses. After ICH, the proteins and metabolites in the brain tissue were significantly altered. Compared with raw rhubarb, wine-processed rhubarb had a better protective effect by dysregulating amino acid metabolism in the ICH model.

Conclusions

Our study provides a basis for further research into the mechanisms of rhubarb treatment from different processing technologies, and promotes the application of rhubarb as a therapeutic approach to ICH.

Riboflavin Is an Important Determinant of Vitamin B-6 Status in Healthy Adults

BACKGROUND

Riboflavin is required to generate the active form of vitamin B-6 (pyridoxal 5'-phosphate; PLP) in tissues, but the relevance of this metabolic interaction for nutritional status of vitamin B-6 is unclear because riboflavin biomarkers are rarely measured in human studies.

OBJECTIVES

The purpose of this study was to identify the determinants of biomarkers of vitamin B-6 and riboflavin status and to examine the relationship between these nutrients in healthy adults.

METHODS

Multiple linear regression was performed on observational data in 407 healthy adults aged 18-92 y who did not use B-vitamin supplements. Vitamin B-6 status was assessed by plasma PLP concentrations and erythrocyte glutathione reductase activation coefficient (EGRac) was used as a functional indicator of riboflavin status.

RESULTS

Dietary intakes of vitamin B-6 and riboflavin were below the average requirements in 10% and 29% of participants, respectively. Suboptimal status of vitamin B-6 (PLP ≤30.0 nmol/L) was more prevalent in adults aged ≥60 y than in younger participants (i.e., 14% compared with 5%), whereas a high proportion (i.e., overall 37%) of both age groups had deficient riboflavin status (EGRac ≥1.40). In multiple regression analysis, EGRac (P = 0.019) was a significant determinant of plasma PLP, along with dietary vitamin B-6 intake (P = 0.003), age (P < 0.001), BMI (kg/m2) (P = 0.031), and methylenetetrahydrofolate reductase gene (MTHFR) genotype (P < 0.001). Significant determinants of EGRac were dietary riboflavin intake (P < 0.001), age (P < 0.001) and MTHFR genotype (P = 0.020). Plasma PLP showed a stepwise decrease across riboflavin status categories from optimal (EGRac ≤1.26) to low (EGRac 1.27-1.39) to deficient status (P = 0.001), independent of dietary vitamin B-6 intake.

CONCLUSIONS

The findings are consistent with the known metabolic dependency of vitamin B-6 on riboflavin status and indicate that riboflavin may be the limiting nutrient, particularly in older people, for maintaining adequate vitamin B-6 status.

Dietary patterns related to cardiovascular disease based on reduced rank regression analysis of healthy middle-aged Koreans: data from the community-based Korean Genome and Epidemiology Study (KoGES) cohort

BACKGROUND

Dietary patterns (DPs) provide a comprehensive picture of the foods consumed by an individual.

OBJECTIVES

Using 12-y follow-up data from the Korean Genome Epidemiology Study (KoGES), we determined the associations of DPs with incident cardiovascular disease (CVD) using reduced rank regression (RRR).

METHODS

This study analyzed the data of 7354 CVD-free subjects aged 40-69 y drawn from the community-based KoGES cohort. Based on the daily intake of 26 food groups at baseline, we identified DPs based on retinol, vitamin B-2 (riboflavin), and vitamin B-3 (niacin) intakes using RRR. The effects of the DPs on incident CVD were assessed using HRs with 95% CIs. Furthermore, using a marginal structural model, the association between DPs and incident CVD was evaluated after adjusting for time-varying confounders.

RESULTS

The incidence of CVD during the follow-up period was 3.7 per 1000 person-years (n = 274). The identified DP accounted for 28.99% of the variation in the response variables (i.e., the intake amounts of all 3 nutrients) and was characterized by high intakes of eggs, fish, milk, and dairy products. The effect of DP quintile on incident CVD differed by sex (Pinteraction = 0.03); the highest DP quintile was associated with a protective effect against the development of CVD in women (HR: 0.44; 95% CI: 0.22, 0.89), but not in men (HR: 1.57; 95% CI: 0.82, 3.00), compared with the lowest quintile. Even after adjusting for time-dependent variables, the effect of DP on incident CVD was significant in women (HR: 0.43; 95% CI: 0.22, 0.84), but not in men (HR: 1.49; 95% CI: 0.71, 3.10).

CONCLUSIONS

In this study, we identified DPs related to CVD, and a DP characterized by high intakes of eggs, fish, milk, and dairy products protected against incident CVD in women.

Brain Ischemia/Reperfusion Injury and Mitochondrial Complex I Damage

Ischemic stroke and neonatal hypoxic-ischemic encephalopathy are two of the leading causes of disability in adults and infants. The energy demands of the brain are provided by mitochondrial oxidative phosphorylation. Ischemia/reperfusion (I/R) affects the production of ATP in brain mitochondria, leading to energy failure and death of the affected tissue. Among the enzymes of the mitochondrial respiratory chain, mitochondrial complex I is the most sensitive to I/R; however, the mechanisms of its inhibition are poorly understood. This article reviews some of the existing data on the mitochondria impairment during I/R and proposes two distinct mechanisms of complex I damage emerging from recent studies. One mechanism is a reversible dissociation of natural flavin mononucleotide cofactor from the enzyme I after ischemia. Another mechanism is a modification of critical cysteine residue of complex I involved into the active/deactive conformational transition of the enzyme. I describe potential effects of these two processes in the development of mitochondrial I/R injury and briefly discuss possible neuroprotective strategies to ameliorate I/R brain injury.

Network pharmacology study of traditional Chinese medicines for stroke treatment and effective constituents screening

ETHNOPHARMACOLOGICAL RELEVANCE

Stroke is one of the most frequent causes of death and disability. So far there are no effective preventives or treatments. The therapeutic system of traditional Chinese medicines (TCMs) has been in use for several thousand years and still affords a valuable resource for today's clinicians in preserving health.

MATERIALS AND METHODS

We had collected the Chinese medicinal formulae and then commonly used single herbs or drug combinations were analyzed through data mining. The ingredients from the top 30 frequently used herbs which have good druggability and blood-brain barrier permeability were collected as a natural product library. Targets of the related ingredients were predicted using various databases and analyzed by GO and KEGG pathway mapping. The potential stroke targets were validated in the market or from clinical trials, and used to establish molecular docking, HipHop and SBP models to screen new compounds for multi-target activity. Lastly, in vitro experiments with models for oxygen and glucose deprivation and reperfusion (OGDR) were conducted to test the activities of compounds identified by screening.

RESULTS

A total of 1679 Chinese medicinal formulas were selected and their prescription rules were analyzed. 4277 compounds were from the top 30 herbs and 3560 molecules were filtered to build the natural product library. The ingredient-target network, target-disease network and target-target interaction network were established to explain the characteristics and mechanisms of the TCMs. Thirty-one molecules were selected to have multi-target activity on targets of stroke via virtual screening. Five of these had already been reported to have therapeutic effects on stroke. Three of the eight compounds which have been examined showed protective effects on OGDR model.

CONCLUSIONS

This paper details a novel strategy for exploring the characteristics and mechanisms of herbal medicines from a systematic standpoint in an attempt to identify those affecting specific target pathways related to stroke. Using this methodology on our natural products library, we found a number of lead candidates with multi-target activity.

Mechanism of mitochondrial complex I damage in brain ischemia/reperfusion injury. A hypothesis

The purpose of this review is to integrate available data on the effect of brain ischemia/reperfusion (I/R) on mitochondrial complex I. Complex I is a key component of the mitochondrial respiratory chain and it is the only enzyme responsible for regenerating NAD+ for the maintenance of energy metabolism. The vulnerability of brain complex I to I/R injury has been observed in multiple animal models, but the mechanisms of enzyme damage have not been studied. This review summarizes old and new data on the effect of cerebral I/R on mitochondrial complex I, focusing on a recently discovered mechanism of the enzyme impairment. We found that the loss of the natural cofactor flavin mononucleotide (FMN) by complex I takes place after brain I/R. Reduced FMN dissociates from the enzyme if complex I is maintained under conditions of reverse electron transfer when mitochondria oxidize succinate accumulated during ischemia. The potential role of this process in the development of mitochondrial I/R damage in the brain is discussed.

Redox-Dependent Loss of Flavin by Mitochondrial Complex I in Brain Ischemia/Reperfusion Injury

Aims: Brain ischemia/reperfusion (I/R) is associated with impairment of mitochondrial function. However, the mechanisms of mitochondrial failure are not fully understood. This work was undertaken to determine the mechanisms and time course of mitochondrial energy dysfunction after reperfusion following neonatal brain hypoxia-ischemia (HI) in mice. Results: HI/reperfusion decreased the activity of mitochondrial complex I, which was recovered after 30 min of reperfusion and then declined again after 1 h. Decreased complex I activity occurred in parallel with a loss in the content of noncovalently bound membrane flavin mononucleotide (FMN). FMN dissociation from the enzyme is caused by succinate-supported reverse electron transfer. Administration of FMN precursor riboflavin before HI/reperfusion was associated with decreased infarct volume, attenuation of neurological deficit, and preserved complex I activity compared with vehicle-treated mice. In vitro, the rate of FMN release during oxidation of succinate was not affected by the oxygen level and amount of endogenously produced reactive oxygen species. Innovation: Our data suggest that dissociation of FMN from mitochondrial complex I may represent a novel mechanism of enzyme inhibition defining respiratory chain failure in I/R. Strategies preventing FMN release during HI and reperfusion may limit the extent of energy failure and cerebral HI injury. The proposed mechanism of acute I/R-induced complex I impairment is distinct from the generally accepted mechanism of oxidative stress-mediated I/R injury. Conclusion: Our study is the first to highlight a critical role of mitochondrial complex I-FMN dissociation in the development of HI-reperfusion injury of the neonatal brain. Antioxid. Redox Signal. 31, 608-622.

Reverse electron transfer results in a loss of flavin from mitochondrial complex I: Potential mechanism for brain ischemia reperfusion injury

Ischemic stroke is one of the most prevalent sources of disability in the world. The major brain tissue damage takes place upon the reperfusion of ischemic tissue. Energy failure due to alterations in mitochondrial metabolism and elevated production of reactive oxygen species (ROS) is one of the main causes of brain ischemia-reperfusion (IR) damage. Ischemia resulted in the accumulation of succinate in tissues, which favors the process of reverse electron transfer (RET) when a fraction of electrons derived from succinate is directed to mitochondrial complex I for the reduction of matrix NAD⁺. We demonstrate that in intact brain mitochondria oxidizing succinate, complex I became damaged and was not able to contribute to the physiological respiration. This process is associated with a decline in ROS release and a dissociation of the enzyme's flavin. This previously undescribed phenomenon represents the major molecular mechanism of injury in stroke and induction of oxidative stress after reperfusion. We also demonstrate that the origin of ROS during RET is flavin of mitochondrial complex I. Our study highlights a novel target for neuroprotection against IR brain injury and provides a sensitive biochemical marker for this process.

Environmental control of microRNAs in the nervous system: Implications in plasticity and behavior

The discovery of microRNAs (miRNAs) a little over 20 years ago was revolutionary given that miRNAs are essential to numerous physiological and physiopathological processes. Currently, several aspects of the biogenic process of miRNAs and of the translational repression mechanism exerted on their targets mRNAs are known in detail. In fact, the development of bioinformatics tools for predicting miRNA targets has established that miRNAs have the potential to regulate almost all known biological processes. Therefore, the identification of the signals and molecular mechanisms that regulate miRNA function is relevant to understanding the role of miRNAs in both pathological and adaptive processes. Recently, a series of studies has focused on miRNA expression in the brain, establishing that their levels are altered in response to various environmental factors (EFs), such as light, sound, odorants, nutrients, drugs and stress. In this review, we discuss how exposure to various EFs modulates the expression and function of several miRNAs in the nervous system and how this control determines adaptation to their environment, behavior and disease state.

Attenuated neuroprotective effect of riboflavin under UV-B irradiation via miR-203/c-Jun signaling pathway in vivo and in vitro

Background

Riboflavin (RF) or vitamin B2 is known to have neuroprotective effects. In the present study, we report the attenuation of the neuroprotective effects of RF under UV-B irradiation. Preconditioning of UV-B irradiated riboflavin (UV-B-RF) showed attenuated neuroprotective effects compared to that of RF in SH-SY5Y neuroblostoma cell line and primary cortical neurons in vitro and a rat model of cerebral ischemia in vivo.

Results

Results indicated that RF pretreatment significantly inhibited cell death and reduced LDH secretion compared to that of the UV-B-RF pretreatment in primary cortical neuron cultures subjected to oxygen glucose deprivation in vitro and cortical brain tissue subjected to ischemic injury in vivo. Further mechanistic studies using cortical neuron cultures revealed that RF treatment induced increased miR-203 expression which in turn inhibited c-Jun expression and increased neuronal cell survival. Functional assays clearly demonstrated that the UV-B-RF preconditioning failed to sustain the increased expression of miR-203 and the decreased levels of c-Jun, mediating the neuroprotective effects of RF. UV-B irradiation attenuated the neuroprotective effects of RF through modulation of the miR-203/c-Jun signaling pathway.

Conclusion

Thus, the ability of UV-B to serve as a modulator of this neuroprotective signaling pathway warrants further studies into its role as a regulator of other cytoprotective/neuroprotective signaling pathways.

Hydrosoluble vitamins

The hydrosoluble vitamins are a group of organic substances that are required by humans in small amounts to prevent disorders of metabolism. Significant progress has been made in our understanding of the biochemical, physiologic and nutritional aspects of the water-soluble vitamins. Deficiency of these particular vitamins, most commonly due to inadequate nutrition, can result in disorders of the nervous system. Many of these disorders have been successfully prevented in developed countries; however, they are still common in developing countries. Of the hydrosoluble vitamins, the nervous system depends the most on vitamins B and C (ascorbic acid) for proper functioning. The B group vitamins include thiamin (vitamin B1), riboflavin (vitamin B2), niacin or niacinamide (vitamin B3), pantothenic acid (vitamin B5), pyridoxine or pyridoxal (vitamin B6) and cobalamin (vitamin B12). Clinical findings depend upon the deficiency of the underlying vitamin; generally, deficiency symptoms are seen from a combination rather than an isolated vitamin deficiency. True hereditary metabolic disorders and serious deficiency-associated diseases are rare and in general limited to particular geographic regions and high-risk groups. Their recognition is truly important as that determines the appropriate therapeutic management. The general availability of vitamins to practically everyone and several national health programs have saved many lives and prevented complications. However, there has been some apprehension for several decades about how harmless generous dosages of these vitamins are. Overt overdosages can cause vitamin toxicity affecting various body systems including the nervous system. Systemically, vitamin toxicity is associated with nonspecific symptoms, such as nausea, vomiting, diarrhea, and skin rash which are common with any acute or chronic vitamin overdose. At a national level, recommended daily allowances for vitamins become policy statements. Nutrition policy has far reaching implications in the food industry, in agriculture, and in food provision programs. Overall, water-soluble vitamins are complex molecular structures and even today, many areas of vitamin biochemistry still need to be explored. Many readers might be of the opinion that the classic forms of nutritional deficiency diseases have faded into the background of interesting history. This has caused their diverse symptoms to be neglected by most modern physicians since vitamin enrichment of many foods automatically erases them from their consideration in differential diagnosis. Vitamin B12 and folic acid deficiencies are discussed in other chapters.

Importance of riboflavin kinase in the pathogenesis of stroke

AIMS

To explore risk factors for stroke independent of hypertension and the relationship between riboflavin kinase (RFK) and stroke.

METHODS

Gene expression profiling in the brains of spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP) was comparatively analyzed by gene chips. The differentially expressed gene RFK was further verified by q-PCR and Western blot. The protective role of RFK-regulated flavins (including riboflavin, flavin mononucleotide, and flavin adenine dinucleotide) in stroke was observed in middle cerebral artery occlusion (MCAO) mice. Influence of flavins on apoptosis and death in oxygen and glucose deprivation (OGD)-treated neurons was examined by flow cytometry. Bax and Bcl-2 proteins were detected by Western blot.

RESULTS

Of the 76 differentially expressed genes, 41 genes were upregulated, and 35 genes were downregulated in SHRSP as compared with SHR. RFK was significantly downregulated in SHRSP. Flavins markedly decreased infarct area in MCAO mice, inhibited apoptosis and death in OGD-treated neurons, and decreased Bax protein expression.

CONCLUSIONS

Physiological downregulation of RFK may be a new potential risk factor for stroke, which probably affects the absorbance and utility of riboflavin and further destroys the protective effect of flavins on stroke. RFK might act as a therapeutic target for stroke.

ACP1 genotype, glutathione reductase activity, and riboflavin uptake affect cardiovascular risk in the obese

Erythrocyte acid phosphatase (ACP locus 1), also known as low-molecular-weight protein tyrosine phosphatase, has previously been associated to glycemia, dyslipidemia, and obesity. In this study, ACP1 genotype and activity were tested in 318 women aged 19 to 83 (mean, 51.74 +/- 13.44) years. ACP1 genotype was found to directly correlate to glutathione reductase activity (P < .001) and levels of low-density lipoprotein cholesterol (P = .038). Glutathione reductase activity was in turn found to correlate to a series of cardiovascular risk factors such as systolic arterial pressure (P < .001), total cholesterol levels (P = .018), and low-density lipoprotein cholesterol levels (P = .039). A possible protective effect of ACP1 genotype AA against these cardiovascular risk factors was observed in this study. Furthermore, this work hypothesizes that nutritional riboflavin uptake becomes more crucial as body mass index increases, to counteract oxidative stress and minimize cardiovascular risk. This might be especially true in ACP1 genotypes AC, BC, and CC, which might possibly show the least endogenous protection against oxidative stress.