Search PubMed⌕ Search

Biomedical subjects

H Wallberg-Henriksson

Publications and source records attributed to H Wallberg-Henriksson.

At least 55 records · Page 3Linked to original sources

Mechanisms behind insulin resistance in rat skeletal muscle after oophorectomy and additional testosterone treatment.

The absence of female sex hormones, as well as testosterone treatment of oophorectomized (OVX) female rats has been demonstrated to result in decreased whole-body insulin-mediated glucose uptake. The cellular mechanism behind this insulin resistance and the role of low levels of female sex hormones as a risk factor for development of peripheral insulin resistance are not yet fully clarified. We assessed the protein expression of GLUT4 and glycogen synthase, as well as insulin-induced translocation of GLUT4 to the plasma membrane, in soleus skeletal muscle from control rats, OVX rats, and OVX rats treated for 8 weeks with testosterone (OVX + T). Whole-body insulin-mediated glucose uptake assessed by the hyperinsulinemic-euglycemic clamp procedure was 25% lower in OVX rats (P < 0.001) and addition of testosterone treatment further decreased insulin-mediated glucose uptake in OVX + T rats by 48% (P < 0.001) compared with controls. GLUT4 protein expression in soleus muscles was unaltered in the OVX and OVX + T rats compared with controls. Insulin induced a 3.7-fold increase (P < 0.05) in the plasma membrane content of GLUT4 in soleus muscle from control rats, whereas plasma membrane content of GLUT4 in soleus muscle from OVX or OVX + T rats was unaltered in response to insulin. Glycogen synthase protein expression in muscle homogenates was decreased by 25% in the OVX group (P < 0.05) and by 37% in the OVX + T group (P < 0.05) when compared with the control group. Insulin receptor and tyrosine kinase activities in the basal and insulin-stimulated states did not differ between the OVX and OVX + T rats. In conclusion, the absence of female sex hormones appears to decrease insulin-mediated whole-body glucose uptake via an impaired insulin-stimulated translocation of GLUT4 to the plasma membrane and by decreased protein expression of glycogen synthase. Testosterone treatment further impairs whole-body insulin-mediated glucose uptake, presumably by additional impairment of glycogen synthase expression.

5'-Nucleotidase↗

Carrier-mediated fructose uptake significantly contributes to carbohydrate metabolism in human skeletal muscle.

To determine whether fructose can be utilized as a metabolic substrate for skeletal muscle in man, we investigated its incorporation into glycogen, its oxidation and lactate production in isolated human skeletal muscle. Rates of fructose oxidation and incorporation into glycogen increased in the presence of increasing fructose concentrations (0.1-1.0 mM). Lactate production increased 3-fold when extracellular fructose was increased from 0.1 to 0.5 mM. Cytochalasin B, a competitive inhibitor of hexose transport mediated by the GLUT1 and GLUT4 facilitative glucose transporters, completely inhibited insulin-stimulated glucose incorporation into glycogen and glucose oxidation (P < 0.01), but did not alter fructose incorporation into glycogen or fructose oxidation. Insulin (1000 mu-units/ml) increased glucose incorporation into glycogen 2.7-fold and glucose oxidation 2.3-fold, whereas no effect on fructose incorporation into glycogen or fructose oxidation was noted. A physiological concentration of glucose (5 mM) decreased the rate of 0.5 mM fructose incorporation into glycogen by 60% (P < 0.001), whereas fructose oxidation was not altered in the presence of 5 mM glucose. Irrespective of fructose concentration, the majority of fructose taken up underwent non-oxidative metabolism. Lactate production accounted for approx. 80% of the fructose metabolism in the basal state and approx. 70% in the insulin (1000 mu-units/ml)-stimulated state. In the presence of 5 mM glucose, physiological concentrations of fructose could account for approximately 10-30% of hexose (glucose + fructose) incorporation into glycogen under non-insulin-stimulated conditions. In conclusion, fructose appears to be transported into human skeletal muscle via a carrier-mediated system that does not involve GLUT4 or GLUT1. Furthermore, under physiological conditions, fructose can significantly contribute to carbohydrate metabolism in human skeletal muscle.

Adult↗

Development of decreased insulin-induced glucose transport in skeletal muscle of glucose-intolerant hybrids of diabetic GK rats.

1. The effect of glucose intolerance on insulin-stimulated glucose transport in isolated skeletal muscles was investigated in male F1 hybrids of spontaneously diabetic GK (Goto-Kakizaki) and control Wistar rats at 1 and 2 months of age. 2. Hybrid rats are characterized by markedly impaired glucose-induced insulin secretion. The area under the blood glucose curve was significantly higher following an intraperitoneal glucose injection (2 g/kg) in hybrid rats in both age groups than in the control rats (P < 0.001). In 2-month-old hybrid rats the incremental area under the insulin curve during the intraperitoneal glucose tolerance test was not different from that of control rats. Serum cholesterol, triacylglycerol or plasma free fatty acid levels did not differ between the groups. Fasting and post-prandial plasma glucose concentrations were elevated in 2-month-old hybrid rats compared with control rats (54%, P < 0.05, and 27%, P < 0.05, respectively), but were not different in 1-month-old rats. Plasma insulin did not differ between the hybrid and control rats in the fasting or post-prandial state at either age studied. 3. The insulin dose-response curves for 3-O-methylglucose transport did not differ between 1-month-old hybrid and control rats for either the soleus or epitrochlearis muscle. The insulin dose-response curve for the epitrochlearis, but not for the soleus, muscle from 2-month-old hybrid rats was shifted to the right compared with the curve from the control animals (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

3-O-Methylglucose↗

Insulin induces translocation of GLUT-4 glucose transporters in human skeletal muscle.

Understanding the molecular mechanisms involved in the regulation of glucose transport into human muscle is necessary to unravel possible defects in glucose uptake associated with insulin resistance in humans. Here we report a strategy to subfractionate human skeletal muscle biopsies (0.5 g) removed from vastus lateralis during a euglycemic insulinemic clamp procedure. A sucrose gradient separated total membranes into five fractions. Fraction 25 (25% sucrose) contained the plasma membrane markers alpha 1- and alpha 2-subunits of the Na(+)-K(+)-adenosinetriphosphatase and the GLUT-5 hexose transporter, recently immunolocalized to the cell surface of human skeletal muscle. The dihydropyridine receptor, a transverse tubule marker, was present exclusively in this fraction. The GLUT-4 glucose transporter was more concentrated in fraction 27.5 (27.5% sucrose) and largely diminished in plasma membrane markers. Open skeletal muscle biopsies were removed before and 30 min after clamping insulin to 550 pM. This increased GLUT-4 protein by 1.61-fold in fraction 25 and lowered it by 50% in fraction 27.5. Thus physiological concentrations of insulin induce translocation of glucose transporters from an internal membrane pool to surface membranes in human skeletal muscle.

Adult↗

Hyperglycemia activates glucose transport in rat skeletal muscle via a Ca(2+)-dependent mechanism.

We investigated the acute effect of hyperglycemia on 3-O-methylglucose transport in isolated rat epitrochlearis muscles. High levels of glucose (20 mmol/l) induced an approximately twofold increase in the rate of glucose transport when compared with muscles exposed to a low level of glucose (8 mmol/l) (P < 0.001). The hyperglycemic effect was additive to the effects of both insulin and exercise on the glucose transport rates. Dantrolene (25 mumol/l), a potent inhibitor of Ca2+ release from the sarcoplasmic reticulum, blocked the ability of hyperglycemia to increase glucose transport by 73% (P < 0.01). Although dantrolene had no effect on the non-insulin-stimulated or the insulin-stimulated glucose transport rates during normoglycemic conditions, the effect of exercise was completely blocked in the presence of dantrolene (P < 0.01). Inhibition of phosphatidylinositol (PI) 3-kinase by wortmannin (500 nmol/l) had no effect on the activation of glucose transport by hyperglycemia, whereas the insulin-stimulated glucose transport was completely abolished (P < 0.001). These findings suggest that hyperglycemia activates glucose transport by a Ca(2+)-dependent activation of glucose transport does not involve the activation of PI 3-kinase and is separate from the mass-action effect of glucose on glucose transport.

3-O-Methylglucose↗

Regulation of human insulin receptor RNA splicing in vivo.

Alternative splicing involving the inclusion or exclusion of exon 11 in insulin receptor mRNA results in two isoforms of the alpha subunit. The two subunits display tissue-specific variation in relative abundance at both RNA and protein levels and discrete differences in biological properties. We have previously reported a small decrease in the relative level of RNA molecules lacking exon 11 (Ex 11-) in skeletal muscle of non-insulin-dependent diabetes mellitus (NIDDM) patients. In the present study, we describe a drastically altered ratio in favor of Ex 11- RNA in a NIDDM patient with markedly impaired insulin-mediated glucose utilization. The ratio between the splice variants changed from 74% to 48% Ex 11- RNA after initiation of insulin treatment, which considerably improved his blood glucose concentrations and insulin-stimulated glucose utilization rate. This shows that splicing can be regulated by metabolic and/or hormonal factors in response to changes in the in vivo milieu. No genomic deletion or base substitution in either the coding regions or exon-intron borders was found that explains the altered splicing. Heterozygous mutations were excluded in sequences of putative importance for splicing outside the analyzed regions as both alleles were expressed and spliced in an identical fashion. Furthermore, these results suggest that this patient fails to regulate alternative splicing of exon 11 in the manner observed in most NIDDM patients and that this defect is associated with the extreme impairment in insulin action.

Alleles↗

Effects of glycaemia on glucose transport in isolated skeletal muscle from patients with NIDDM: in vitro reversal of muscular insulin resistance.

We investigated the influence of altered glucose levels on insulin-stimulated 3-0-methylglucose transport in isolated skeletal muscle obtained from NIDDM patients (n = 13) and non-diabetic subjects (n = 23). Whole body insulin sensitivity was 71% lower in the NIDDM patients compared to the non-diabetic subjects (p < 0.05), whereas, insulin-mediated peripheral glucose utilization in the NIDDM patients under hyperglycaemic conditions was comparable to that of the non-diabetic subjects at euglycaemia. Following a 30-min in vitro exposure to 4 mmol/l glucose, insulin-stimulated 3-0-methylglucose transport (600 pmol/l insulin) was 40% lower in isolated skeletal muscle strips from the NIDDM patients when compared to muscle strips from the non-diabetic subjects. The impaired capacity for insulin-stimulated 3-0-methylglucose transport in the NIDDM skeletal muscle was normalized following prolonged (2h) exposure to 4 mmol/l, but not to 8 mmol/l glucose. Insulin-stimulated 3-0-methylglucose transport in the NIDDM skeletal muscle exposed to 8 mmol/l glucose was similar to that of the non-diabetic muscle exposed to 5 mmol/l glucose, but was decreased by 43% (p < 0.01) when compared to non-diabetic muscle exposed to 8 mmol/l glucose. Despite the impaired insulin-stimulated 3-0-methylglucose transport capacity demonstrated by skeletal muscle from the NIDDM patients, skeletal muscle glycogen content was similar to that of the non-diabetic subjects. Kinetic studies revel a Km for 3-0-methylglucose transport of 9.7 and 8.8 mmol/l glucose for basal and insulin-stimulated conditions, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

3-O-Methylglucose↗

Does C-peptide have a physiological role?

Short-term administration of physiological amounts of C-peptide to patients with insulin-dependent diabetes was found to reduce the glomerular hyperfiltration in these patients as well as augment whole body glucose utilization. It could also be shown that C-peptide administration increases blood flow, oxygen uptake and capillary diffusion capacity of exercising forearm muscle in IDDM patients, probably by increasing capillary recruitment in the working muscle. Studies under in vitro conditions have shown that C-peptide stimulates glucose transport in skeletal muscle with its maximal effect within the physiological concentration range. The findings in a clinical study in which IDDM patients were given C-peptide and insulin or insulin alone for 4 weeks in a double-blind randomized study design, indicate that C-peptide improves renal function by reducing urinary albumin excretion and glomerular filtration, decreases blood retinal barrier leakage and improves metabolic control. Preliminary findings suggest that C-peptide administration on a short-term basis (3h) may ameliorate autonomic neuropathy by restoring to near normal the heart rate variability in response to expiration and inspiration. Insight into a possible mechanism of action of C-peptide is provided by the finding that C-peptide stimulates Na+K(+)-ATPase activity in renal tubular segments. In conclusion, the present results suggest that, contrary to the prevailing view, C-peptide possesses important physiological effects.

Animals↗

Effect of metformin on insulin-stimulated glucose transport in isolated skeletal muscle obtained from patients with NIDDM.

Metformin has been demonstrated to lower blood glucose in vivo by a mechanism which increases peripheral glucose uptake. Furthermore, the therapeutic concentration of metformin has been estimated to be in the order of 0.01 mmol/l. We investigated the effect of metformin on insulin-stimulated 3-0-methylglucose transport in isolated skeletal muscle obtained from seven patients with non-insulin-dependent diabetes mellitus (NIDDM) and from eight healthy subjects. Whole body insulin-mediated glucose utilization was decreased by 45% (p < 0.05) in the diabetic subjects when studied at 8 mmol/l glucose, compared to the healthy subjects studied at 5 mmol/l glucose. Metformin, at concentrations of 0.1 and 0.01 mmol/l, had no effect on basal or insulin-stimulated (100 microU/ml) glucose transport in muscle strips from either of the groups. However, the two control subjects and three patients with NIDDM which displayed a low rate of insulin-mediated glucose utilization (< 20 mumol.kg-1.min-1), as well as in vitro insulin resistance, demonstrated increased insulin-stimulated glucose transport in the presence of metformin at 0.1 mmol/l (p < 0.05). In conclusion, the concentration of metformin resulting in a potentiating effect on insulin-stimulated glucose transport in insulin-resistant human skeletal muscle is 10-fold higher than the therapeutic concentrations administered to patients with NIDDM. Thus, it is conceivable that the hypoglycaemic effect of metformin in vivo may be due to an accumulation of the drug in the extracellular space of skeletal muscle, or to an effect of the drug distal to the glucose transport step.

3-O-Methylglucose↗

Effects of non-esterified fatty acids on insulin-stimulated glucose transport in isolated skeletal muscle from patients with type 2 (non-insulin-dependent) diabetes mellitus.

The influence of elevated levels of oleate on insulin-stimulated 3-0-methylglucose transport was assessed in vitro, in isolated skeletal muscle obtained from patients with type 2 (non-insulin-dependent) diabetes mellitus (n = 7) and control subjects (n = 8). An increase in oleate levels from 0.3 to 1.0 mmol/l induced a 3.7-fold increase in the rate of oleate oxidation (P < 0.01) in skeletal muscle from control subjects. However, the rate of insulin-stimulated 3-0-methylglucose transport was not altered in isolated skeletal muscle from the control subjects or the type 2 diabetic patients following exposure to 1.0 mmol/l oleate. This observation indicates that elevation of non-esterified fatty acids to a high physiological level has no inhibitory effect on glucose transport.

3-O-Methylglucose↗

Elevated free fatty acid levels inhibit glucose phosphorylation in slow-twitch rat skeletal muscle.

The effect of increased free fatty acid concentrations on glucose metabolism in rat skeletal muscle was investigated at several different steps in glucose metabolism including glucose transport, glucose phosphorylation, glucose oxidation and glycogen synthesis. In isolated soleus (slow-twitch) muscles, insulin-stimulated (100 microU ml-1) glucose phosphorylation, but not glucose transport, was inhibited by 26 and 22% in the presence of 1.0 and 2.0 mM oleate, respectively (P < 0.01). Regardless of oleate concentration (0.3 or 2.0 mM), insulin-stimulated glucose 6-phosphate levels were elevated to the same extent over the non-insulin-stimulated levels in soleus muscles (P < 0.01). Insulin-stimulated glucose oxidation was inhibited by 44% in soleus muscles exposed to 2.0 mM oleate (P < 0.05), whereas the rate of glucose incorporation into glycogen was not altered. In insulin-stimulated epitrochlearis (fast-twitch) muscles, elevated concentrations of oleate had no effect on the rates of glucose transport or glucose phosphorylation, or on the level of glucose 6-phosphate. These data suggest that increased free fatty acid availability decreases glucose utilization by selectively inhibiting glucose phosphorylation and oxidation in slow-twitch, but not fast-twitch skeletal muscle.

3-O-Methylglucose↗

Insulin action on glucose transport in isolated skeletal muscle from patients with liver cirrhosis.

Insulin resistance, associated with liver cirrhosis, has been suggested to be localized in skeletal muscle. We used an in vitro incubation technique to determine insulin action on glucose transport in skeletal muscle obtained from seven patients with clinically stable alcoholic cirrhosis and seven healthy age- and sex-matched individuals. In addition, a euglycemic-hyperinsulinemic clamp procedure was performed to assess whole-body insulin-mediated glucose uptake. Insulin-mediated peripheral glucose utilization was 40% lower (p < 0.05) in the cirrhotic patients than in the healthy individuals. Intact skeletal muscle from the vastus lateralis portion of the quadriceps femoris muscle was obtained from each study participant. Thereafter, smaller skeletal muscle strips (approximately 18 mg) were dissected free and incubated in vitro to assess the rate of non-insulin- and insulin-stimulated 3-O-methylglucose transport. Insulin increased the rate of 3-O-methylglucose transport in a dose-dependent manner, with a maximal response observed in the presence of 200 microU/ml in skeletal muscle obtained from the cirrhotic patients and healthy individuals. The dose-response curve for insulin-stimulated 3-O-methylglucose transport did not differ between the groups. Furthermore, muscle glycogen content of needle biopsy specimens was comparable in the two groups. In conclusion, the present group of patients, with liver cirrhosis on an alcoholic basis, had a normal insulin-stimulated capacity for glucose transport at the cellular level irrespective of the degree of whole-body insulin resistance. The mechanism for the divergence between the in vivo and in vitro responses to insulin remains to be elucidated.

3-O-Methylglucose↗

Differences in the ratio of RNA encoding two isoforms of the insulin receptor between control and NIDDM patients. The RNA variant without Exon 11 predominates in both groups.

Two alternative forms of the insulin receptor with different affinities for insulin are expressed as a result of alternative splicing of RNA corresponding to exon 11 of the IR gene. The percentage of IR-RNA molecules without exon 11, encoding the high-affinity isoform, was determined by cDNA-mediated PCR amplification of RNA extracts from the quadriceps femoris muscle of healthy control subjects (n = 9) and NIDDM patients (n = 7). In both patients and control individuals, a majority of the IR-RNA molecules contained exon 11. In addition, the proportion of IR-RNA molecules without exon 11 was decreased in patients (21 +/- 1%) compared with control subjects (31 +/- 3%) (P = 0.018). Careful investigation of the kinetics of the PCR-based assay system, as well as the conditions for separation of the PCR products, allowed us to suggest a possible explanation of the discrepant results concerning the alternative splicing presented in previous reports. The diabetic subjects as a group had higher fasting insulin levels and lower insulin-mediated glucose uptake during a euglycemic-hyperinsulinemic clamp (P = 0.042). However, identification of the regulatory pathways leading to the splicing alteration in NIDDM patients requires further investigation.

Alternative Splicing↗

Insulin-like growth factor II stimulates glucose transport in human skeletal muscle.

We investigated the effect of insulin-like growth factor II (IGF-II) and insulin-like growth factor binding protein-1 (IGFBP-1) on 3-O-methylglucose transport in incubated human skeletal muscle strips. Increasing physiological concentrations of IGF-II stimulated glucose transport in a dose-dependent manner. Glucose transport was maximally stimulated in the presence of 100 ng/ml (13.4 nM) of IGF-II, which corresponded to the effect obtained by 100 microU/ml (0.6 nM) of insulin. Exposure of muscle strips to IGFBP-1 (500 ng/ml) inhibited the maximal effect of IGF-II on glucose transport by 40%. Thus, it is conceivable that IGF-II and IGFBP-1 are physiological regulators of the glucose transport process in human skeletal muscle.

Adult↗

Human islet amyloid polypeptide at pharmacological levels inhibits insulin and phorbol ester-stimulated glucose transport in in vitro incubated human muscle strips.

Human islet amyloid polypeptide, at concentrations of 1-100 nmol/l, has been demonstrated to inhibit the insulin-stimulated increase in rat muscle glycogen content. However, at physiological concentrations (1-10 pmol/l) of islet amyloid polypeptide, no effects have been reported. We tested the effect of a wide range of concentrations of human islet amyloid polypeptide on insulin- and phorbol ester-stimulated 3-0-methylglucose transport in in vitro incubated human skeletal muscle. Muscle specimens from the quadriceps femoris muscle were obtained from 23 healthy subjects with the use of a newly-developed open muscle biopsy technique. Human islet amyloid polypeptide at a concentration of 100 nmol/l had no effect on basal glucose transport, but inhibited the stimulatory effect of a maximal insulin concentration (1000 microU/ml) by 69% (p less than 0.001). The presence of human islet amyloid polypeptide at 1, 10 and 100 nmol/l decreased the effect of 100 microU/ml of insulin on glucose transport by 61% (p less than 0.05), 78% (p less than 0.05) and 76% (p less than 0.05), respectively. Similarly, human islet amyloid polypeptide at a concentration of 10 nmol/l inhibited phorbol ester-stimulated glucose transport by 100% (p less than 0.05). The inhibitory effects of human islet amyloid polypeptide on glucose transport were present in the muscle strips despite no net changes in glycogen content. Human islet amyloid polypeptide at 10 and 100 pmol/l had no effect on the rate of insulin-stimulated glucose transport.(ABSTRACT TRUNCATED AT 250 WORDS)

3-O-Methylglucose↗

Exercise training in obese diabetic patients. Special considerations.

The relationship between obesity and type II diabetes mellitus is well established and a majority of type II diabetic individuals are classified as obese. The pathogenesis of type II diabetes mellitus is not fully understood; however, multiple organ systems are involved, including abnormalities of insulin secretion, peripheral insulin resistance and hepatic insulin resistance. The goal of the treatment for the obese diabetic is to normalise these alterations and achieve normoglycaemia. Traditionally, the initial therapy, aiming to accomplish weight reduction, is diet and exercise. In obese type II diabetic patients, the whole body insulin-dose response curve is markedly depressed. A single exercise session improves and partially normalises both insulin responsiveness and sensitivity for glucose utilisation. Furthermore, a single bout of physical activity often results in decreased plasma glucose levels, which persists into the postoperative period. Type II diabetes patients participating in regular exercise programmes can potentially improve their metabolic control. An improved glucose control in both lean and obese type II diabetic patients under the age of 55 years has been demonstrated by improved HbA1C levels and glucose tolerance tests following physical training programmes. The effect of regular exercise on the metabolic control in these younger patients does not appear to be correlated with weight reduction. For most type II diabetic men over 55 years of age, physical training is not a feasible form of therapy because of other interfering diseases which may complicate or severely hinder all physical training apart from very low intensity exercise programmes. Lean, older, type II diabetic patients who have been able to exercise for 10 weeks or up to 2 years demonstrate no change in HbA1C levels, glucose tolerance or bodyweight. Thus, there is a clear difference in metabolic response to regular exercise between younger and older type II diabetic patients. The younger patient appears to be more inclined to respond to physical training with improvements in the metabolic control. The reason for this apparent difference is not clear, but possible explanations may include differences in training intensity, the presence or degree of complicating diseases, pretraining level of metabolic control or bodyweight. Type II diabetics are predisposed to cardiovascular disease and are characterised by hyperlipidaemia. In obese type II diabetic individuals, physical training improves the blood lipid profile as measured by decreased levels of triglycerides and total cholesterol. In young, overweight diabetics, improved lipid profiles can be achieved despite no change in bodyweight, while no apparent effects are reported for lean patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Glucose↗

Interaction of exercise and insulin in type II diabetes mellitus.

In skeletal muscle, at the level of glucose transport, insulin resistance appears to be a major alteration responsible for decreased glucose disposal rates in non-insulin-dependent (type II) diabetes mellitus. This study focuses on in vitro studies of the glucose transport process in human and rat skeletal muscle. Muscle strips from a group of lean type II diabetic patients demonstrated a 50% decrease in insulin responsiveness for glucose transport when compared with nondiabetic subjects. These findings indicate the presence of postreceptor defects in type II diabetic muscles. Furthermore, in an isolated muscle preparation, it could be demonstrated that epitrochlearis muscles from streptozocin-induced diabetic rats were not only resistant to insulin, but also to exercise-induced increase in glucose transport. However, both regular physical exercise and insulin therapy normalized the decreased capacity for glucose transport in the diabetic rat muscles. Therefore, it appears that regular physical exercise and, in some cases insulin therapy, would be advisable for type II diabetic patients with marked muscular insulin resistance to improve peripheral glucose disposal rates.

3-O-Methylglucose↗