Title
Growth of Candida albicans in a minimal synthetic medium without biotin.
Author
Vidotto V; Pugliese A; Gioannini P
Source
Mycopathologia, 1987 Oct, 100:1, 7-15
Abstract
Growth of Candida albicans strain B 311-10 was observed in a minimal synthetic biotin-free medium, using different glucose concentrations, during the first 30 hours of its development at 28 degrees C. The yeast's growth was observed spectrophotometrically at 675 nm reading its optical density every hour. The minimal medium of Shepherd et al., with glucose (15 g/L) and biotin was modified: this vitamin was eliminated and the concentration of glucose was gradually lowered to 0.5 g/L. At 5 g/L of glucose and without biotin very good growth was obtained. Based on our results during the first 30 hours of growth, biotin has no influence on the yeast's growth. This medium would be useful for the study of the physiology of C. albicans during the first period of its development.

Title
Importance of some factors on the dimorphism of Candida albicans.
Author
Vidotto V; Picerno G; Caramello S; Paniate G
Source
Mycopathologia, 1988 Dec, 104:3, 129-35
Abstract
The passage between the yeast and mycelial forms of Candida albicans B 311-10 was studied by using the minimal synthetic medium of Shepherd et al. modified without biotin and with low glucose concentrations. It was observed that biotin, aminoacids and particularly pH are not important factors in the dimorphism of C. albicans. The only factor of notable importance in the passage of yeast form to mycelial form in C. albicans was glucose concentration.

Title
Biotin production by bifidobacteria.
Author
Noda H; Akasaka N; Ohsugi M
Source
J Nutr Sci Vitaminol (Tokyo), 1994 Apr, 40:2, 181-8
Abstract
Biotin production and the growth of the strains of Bifidobacterium adolescentis, B. bifidum, B. breve, B. infantis, and B. longum were studied. These five strains showed heavy growth on BL medium. But when yeast extract medium (carbon Source, glucose) was used, the extent of their growth was significantly decreased, one-half or less than that of the growth on BL medium. B. bifidum grew well on yeast extract medium containing oligosaccharides, such as isomaltooligosaccharide, and produced biotin extracellularly. The utilization of oligosaccharides in biotin production by these five strains was investigated.

Title
A high biotin diet improves the impaired glucose tolerance of long-term spontaneously hyperglycemic rats with non-insulin-dependent diabetes mellitus.
Author
Zhang H; Osada K; Maebashi M; Ito M; Komai M; Furukawa Y
Source
J Nutr Sci Vitaminol (Tokyo), 1996 Dec, 42:6, 517-26
Abstract
The Otsuka Long-Evans Tokushima Fatty (OLETF) rat, serving as a spontaneously diabetic model with non-insulin-dependent diabetes mellitus (NIDDM), exhibits impaired glucose tolerance (IGT) at about 16 weeks of age. In this study, we investigated whether or not biotin, a water-soluble vitamin, improved the IGT of OLETF rats. To this end, we administered diets containing one of three levels of biotin, a high-biotin diet (BH), a normal-biotin diet (BN) and a basal-biotin diet (BB), to OLETF rats up to 24 weeks of age. An oral glucose tolerance test (OGTT) was performed four times between 13 and 22 weeks of age. The administration of a BH corrected the IGT of OLETF rats. Upon further investigation, we found that insulin secretion in the OLETF-BH rats was decreased to a significant extent, signaling that the hyperinsulinemia typical to the OLETF-BH rats had clearly improved. Body weights were significantly lower in the OLETF-BH group than in the other OLETF groups, even though the OLETF-BH rats showed a significantly higher average daily food intake. The body weight gain of the OLETF-BH rats followed the same tendency as the control-LETO (Long Evans Tokushima Otsuka) rats (LETO-BB and LETO-BN). These results demonstrate that a high-level biotin diet can improve the glucose handicap in NIDDM rats.

Title
Oral glucose tolerance test after high-dose i.v. biotin administration in normoglucemic hemodialysis patients.
Author
Koutsikos D; Fourtounas C; Kapetanaki A; Agroyannis B; Tzanatos H; Rammos G; Kopelias I; Bosiolis B; Bovoleti O; Darema M; Sallum G
Source
Ren Fail, 1996 Jan, 18:1, 131-7
Abstract
Abnormal glucose metabolism in uremia may result from a complex interplay between decreased insulin secretion and insulin resistance. Recent studies report beneficial effect of biotin administration in glucose metabolism in diabetic animals and in a small number of patients with diabetes mellitus. The aim of the present study was to evaluate the response of oral glucose tolerance test (OGTT) to the i.v. administration of large doses of biotin in hemodialysis patients. Eleven hemodialysis patients aged 56.90 +/- 11.20 (32-76) years on regular hemodialysis thrice a week for 2.72 +/- 1.79 (1-7) years were studied. Fasting venous plasma glucose, glucosylated hemoglobin (%GH), and plasma glucose concentration 2 h after the administration of a 75-g glucose load were measured before, and 2 weeks and 2 months after administration of 50 mg of biotin i.v. postdialysis, and after a 2-month washout period. During the study, dialysis schedule and patients' medication, diet, and dry weight were kept unchanged. OGTT was abnormal in 4 patients before biotin administration and became normal in 3 patients (75%). Our results offer support to the findings of other studies about the beneficial effect of biotin in experimental or clinical diabetes mellitus, and argue for the involvement of biotin in glucose metabolism.

Title
Influence of glucose on pyruvate carboxylase expression in pancreatic islets.
Author
MacDonald MJ
Source
Arch Biochem Biophys, 1995 May, 319:1, 128-32
Abstract
Pancreatic islets were cultured for 1 day in the presence of 1 to 20 mM glucose and islet proteins were separated on polyacrylamide gels and transferred to nitrocellulose. Pyruvate carboxylase and an unidentified biotin-containing protein were visualized with [125I]streptavidin followed by autoradiography. The amount of pyruvate carboxylase was proportional to the concentration of glucose. Estimates of the amount of the enzyme in islets were made by comparing the density of the islet pyruvate carboxylase band with a standard curve of various amounts of authentic pyruvate carboxylase. This indicated that the enzyme comprised 0.4% of total islet protein. Net synthesis of the enzyme was increased by cAMP and methyl succinate. A nuclear run-on assay showed that glucose caused increases in pyruvate carboxylase and pyruvate dehydrogenase E1 alpha subunit transcripts and decreases in branched chain ketoacid dehydrogenase E1 alpha transcripts in rat insulinoma (RINm5F) cells. Pancreatic islets cultured in the presence of 1 mM glucose for 1 day cannot respond to glucose with insulin release. Previous studies demonstrated that carbon flux into the citric acid cycle intermediates via both carboxylation and decarboxylation is decreased in glucose-incapacitated islets (M. J. MacDonald, 1993, Arch. Biochem. Biophys. 300, 205-214), 1993). The current results support the idea that carboxylation of glucose-derived pyruvate, as well as decarboxylation of pyruvate, is important for glucose-induced insulin secretion.

Title
Biotin administration improves the impaired glucose tolerance of streptozotocin-induced diabetic Wistar rats.
Author
Zhang H; Osada K; Sone H; Furukawa Y
Source
J Nutr Sci Vitaminol (Tokyo), 1997 Jun, 43:3, 271-80
Abstract
The effect of biotin administration on the glucose tolerance of streptozotocin (STZ)-induced diabetic Wistar rats was investigated. STZ-induced diabetes was induced by intraperitoneal injection of streptozotocin (45 mg/kg body weight as a single dose). The impaired glucose tolerance in response to an oral glucose load (1.8g per kg body weight) in STZ-induced diabetic rats (STZ-rat) was partially improved by intraperitoneal administration of biotin for 15 days (100 micrograms/rat/day). However, a recovery in the STZ-rat's insulin secretion was not found after biotin administration. To help clarify the mechanism underlying the improvement in glucose tolerance seen with biotin treatment, glucokinase and hexokinase activities were determined in the liver and pancreas. In STZ-rats that had received biotin (STZ-biotin rats), glucokinase activity was higher by 3.4-fold in liver and by 2.4-fold in pancreas than in the STZ-rats. The biotin level of STZ-rats was significantly lower in the liver and pancreas than that of the control rats (no STZ administration); but in STZ-biotin rats, the level in these organs recovered to the control level. These results demonstrate that injected biotin can improve glucose handling without increasing insulin secretion in STZ-rats.

Title
Optimum nutrition: thiamin, biotin and pantothenate.
Author
Bender DA
Source
Proc Nutr Soc, 1999 May, 58:2, 427-33
Abstract
The metabolism of glucose is deranged in thiamin deficiency, but once any deficiency has been corrected there is no further effect of increased thiamin intake on the ability to metabolize glucose through either pyruvate dehydrogenase (EC 1.2.4.1) and the citric acid cycle, or the pentose phosphate pathway, in which transketolase (EC 2.2.1.1) is the thiamin-dependent step. It has been suggested that the Wernicke-Korsakoff syndrome is associated with a genetic variant of transketolase which requires a higher than normal concentration of thiamin diphosphate for activity. This finding would suggest that there may be a group of the population who have a higher than average requirement for thiamin, but the evidence is not convincing. There are no estimates of biotin requirements, but either coenzyme saturation of erythrocyte pyruvate carboxylase, or the excretion of 3-hydroxy-isovalerate (perhaps after a test dose of leucine) could be used to assess requirements in depletion-repletion studies. Biotin deficiency leads to impaired glucose tolerance, but it is unlikely that glucose tolerance could be used to assess optimum biotin status, since other more common factors affect glucose tolerance to a greater extent. Plasma triacylglycerol and nonesterified fatty acids are moderately elevated in pantothenic acid deficiency. However, this is unlikely to be useful in assessing pantothenate status, since again, other more common factors affect plasma lipids. To date there are no biochemical indices of adequate pantothenate nutrition, and no estimates of requirements.

Title
High-dose biotin, an inducer of glucokinase expression, may synergize with chromium picolinate to enable a definitive nutritional therapy for type II diabetes.
Author
McCarty MF
Source
Med Hypotheses, 1999 May, 52:5, 401-6
Abstract
Glucokinase (GK), expressed in hepatocyte and pancreatic beta cells, has a central regulatory role in glucose metabolism. Efficient GK activity is required for normal glucose-stimulated insulin secretion, postprandial hepatic glucose uptake, and the appropriate suppression of hepatic glucose output and gluconeogenesis by elevated plasma glucose. Hepatic GK activity is subnormal in diabetes, and GK may also be decreased in the beta cells of type II diabetics. In supraphysiological concentrations, biotin promotes the transcription and translation of the GK gene in hepatocytes; this effect appears to be mediated by activation of soluble guanylate cyclase. More recent evidence indicates that biotin likewise increases GK activity in islet cells. On the other hand, high-dose biotin suppresses hepatocyte transcription of phosphoenolpyruvate carboxykinase, the rate-limiting enzyme for gluconeogenesis. Administration of high-dose biotin has improved glycemic control in several diabetic animals models, and a recent Japanese clinical study concludes that biotin (3 mg t.i.d. orally) can substantially lower fasting glucose in type II diabetics, without side-effects. The recently demonstrated utility of chromium picolinate in type II diabetes appears to reflect improved peripheral insulin sensitivity--a parameter which is unlikely to be directly influenced by biotin. Thus, the joint administration of supranutritional doses of biotin and chromium picolinate is likely to combat insulin resistance, improve beta-cell function, enhance postprandial glucose uptake by both liver and skeletal muscle, and inhibit excessive hepatic glucose production. Conceivably, this safe, convenient, nutritional regimen will constitute a definitive therapy for many type II diabetics, and may likewise be useful in the prevention and management of gestational diabetes. Biotin should also aid glycemic control in type I patients.

Title
Biotin regulation of pancreatic glucokinase and insulin in primary cultured rat islets and in biotin-deficient rats.
Author
Romero Navarro G; Cabrera Valladares G; German MS; Matschinsky FM; Velazquez A; Wang J; Fernandez Mejia C
Source
Endocrinology, 1999 Oct, 140:10, 4595-600
Abstract
Biotin has been reported to affect glucose homeostasis; however, its role on pancreatic islets of Langerhans has not been assessed. In this report, we demonstrate that physiologic concentrations of biotin stimulate glucokinase activity in rat islets in culture. Using the branched DNA (bDNA) assay, a sensitive signal amplification technique, we detected relative increases in glucokinase mRNA levels of 41.5 +/- 13% and 81.3 +/- 19% at 12 and 24 h respectively in islets treated with [10(-6) M] biotin. Because glucokinase activity controls insulin secretion, we also investigated the effect of biotin on insulin release. Treatment with [10(-6) M] biotin for 24 h increased insulin secretion. We extended our studies by analyzing the effect of biotin deficiency on pancreatic islet glucokinase expression and activity, as well as insulin secretion. Our results show that islet glucokinase activity and mRNA are reduced by 50% in the biotin deficient rat. Insulin secretion in response to glucose was also impaired in islets isolated from the deficient rat. These data show that biotin affects pancreatic islet glucokinase activity and expression and insulin secretion in cultured islets.