Active lifestyles moderate clinical outcomes in autosomal dominant frontotemporal degeneration.

INTRODUCTION: Leisure activities impact brain aging and may be prevention targets. We characterized how physical and cognitive activities relate to brain health for the first time in autosomal dominant frontotemporal lobar degeneration (FTLD). METHODS: A total of 105 mutation carriers (C9orf72/MAPT/GRN) and 69 non-carriers reported current physical and cognitive activities at baseline, and completed longitudinal neurobehavioral assessments and brain magnetic resonance imaging (MRI) scans. RESULTS: Greater physical and cognitive activities were each associated with an estimated >55% slower clinical decline per year among dominant gene carriers. There was also an interaction between leisure activities and frontotemporal atrophy on cognition in mutation carriers. High-activity carriers with frontotemporal atrophy (-1 standard deviation/year) demonstrated >two-fold better cognitive performances per year compared to their less active peers with comparable atrophy rates. DISCUSSION: Active lifestyles were associated with less functional decline and moderated brain-to-behavior relationships longitudinally. More active carriers "outperformed" brain volume, commensurate with a cognitive reserve hypothesis. Lifestyle may confer clinical resilience, even in autosomal dominant FTLD.

Synergistic induction of interleukin-6 expression by endothelin-1 and cyclic AMP in adipocytes.

BACKGROUND: We have demonstrated previously that endothelin-1 (ET-1) may stimulate interleukin-6 (IL-6) release from 3T3-L1 adipocytes. In this study, we further examined the combined effect of ET-1 and cyclic adenosine monophosphate (cAMP) on IL-6 release. METHODS: IL-6 release was measured by enzyme-linked immuosorbent assay. Reverse transcriptase-PCR and real-time PCR analyses were used to determine cellular mRNA levels. A luciferase reporter driven by promoter (-1310/+198) of mouse IL-6 gene was transfected into 3T3-L1 adipocytes to monitor IL-6 transcription. RESULTS: ET-1 and cAMP induced IL-6 release in a synergistic manner that can be attributed to their synergistic induction of IL-6 gene expression, as evidenced by IL-6 mRNA analysis and the IL-6 promoter reporter assay. Both ET(A) and ET(B) receptors seem to be involved. In addition, enhanced IL-6 promoter activity can be similarly induced by ET-1 and catecholamines (epinephrine and norepinephrine). The cooperative interaction between ET-1 and cAMP on IL-6 expression seems distinctive, as no other proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and IL-1ß, are similarly affected. In fact, cAMP inhibited ET-1-stimulated TNF-α and IL-1ß expressions in adipocytes. Furthermore, injection of mice with epinephrine and ET-1 induced a tremendously synergistic increase in serum IL-6 levels. Nevertheless, whereas cAMP induced IL-6 expression in RAW264.7 mouse macrophages, ET-1 had no effect on either the basal or the cAMP-induced IL-6 expression. CONCLUSION: ET-1 and epinephrine may boost plasma IL-6 levels in mice in a synergistic manner, probably through their synergistic induction of IL-6 expression in adipocytes. SIGNIFICANCE: This study should provide a new perspective for treating IL-6-related diseases, especially those accompanied with elevated ET-1 and catecholamine levels.

Elevated PTTG and PBF predicts poor patient outcome and modulates DNA damage response genes in thyroid cancer.

The proto-oncogene PTTG and its binding partner PBF have been widely studied in multiple cancer types, particularly thyroid and colorectal, but their combined role in tumourigenesis is uncharacterised. Here, we show for the first time that together PTTG and PBF significantly modulate DNA damage response (DDR) genes, including p53 target genes, required to maintain genomic integrity in thyroid cells. Critically, DDR genes were extensively repressed in primary thyrocytes from a bitransgenic murine model (Bi-Tg) of thyroid-specific PBF and PTTG overexpression. Irradiation exposure to amplify p53 levels further induced significant repression of DDR genes in Bi-Tg thyrocytes (P=2.4 × 10-4) compared with either PBF- (P=1.5 × 10-3) or PTTG-expressing thyrocytes (P=NS). Consistent with this, genetic instability was greatest in Bi-Tg thyrocytes with a mean genetic instability (GI) index of 35.8±2.6%, as well as significant induction of gross chromosomal aberrations in thyroidal TPC-1 cells following overexpression of PBF and PTTG. We extended our findings to human thyroid cancer using TCGA data sets (n=322) and found striking correlations with PBF and PTTG expression in well-characterised DDR gene panel RNA-seq data. In addition, genetic associations and transient transfection identified PBF as a downstream target of the receptor tyrosine kinase-BRAF signalling pathway, emphasising a role for PBF as a novel component in a pathway well described to drive neoplastic growth. We also showed that overall survival (P=1.91 × 10-5) and disease-free survival (P=4.9 × 10-5) was poorer for TCGA patients with elevated tumoural PBF/PTTG expression and mutationally activated BRAF. Together our findings indicate that PBF and PTTG have a critical role in promoting thyroid cancer that is predictive of poorer patient outcome.

Effects of ionophore A23187 and lanthanum on pepsinogen secretion from frog esophageal mucosa in vitro.

The role of Ca2+ in the mediation of pepsinogen secretion from frog esophagus was investigated by means of ionophore A23187 and LaCl3. The esophageal mucosa from Asian bullfrog Rana tigerina was mounted in a double-chamber system to preserve its polarity and was incubated in a medium containing 1.5 mM CaCl2. Pepsinogen secreted was measured and expressed as % of total. The basal secretion averaged 3.5%/h. Bethanechol (25 microM), dibutyryl-cAMP (10 mM), ionophore A23187 (30 microM) and 3-isobutyl-1-methylxanthine (0.1 mM) increased the secretion to 8.7, 7.4, 7.1 and 6.8%, respectively. The stimulatory effect of bethanechol and of dibutyryl-cAMP were not affected by removing the exogenous Ca2+ with EGTA. The basal secretion was, however, reduced by 50% when Ca2+ in the incubation medium was lowered to 20 microM. At this low Ca2+ concentration, ionophore A23187 not only lost its stimulatory effect but also diminished the stimulation caused by bethanechol and dibutyryl-cAMP. While LaCl3 at 1 mM had no effect on basal and bethanechol-stimulated secretion, at 10 mM it abolished the stimulation evoked by bethanechol or dibutyryl-cAMP. The conclusions are: (1) both Ca2+ and cAMP are involved in the mediation of pepsinogen secretion from frog esophagus, (2) basal secretion is dependent on extracellular Ca2+, whereas bethanechol-stimulated secretion is not, (3) in the plasma membranes of peptic cells may exist a distinct Ca2+ pool (La3+-and ionophore A23187-sensitive) which is involved in the stimulated pepsinogen secretion.

Differential inhibition of lipolysis by 2-bromopalmitic acid and 4-bromocrotonic acid in 3T3-L1 adipocytes.

Two inhibitors of fatty acid oxidation, 2-bromopalmitic acid (Br-C16) and 4-bromocrotonic acid (Br-C4) were examined for their effect on lipolysis in 3T3-L1 adipocytes. Both agents inhibited in a dose-dependent manner the rate of oxidation of exogenously added [1-14C]palmitate with similar time-courses, reaching a plateau at 3-9 h. While Br-C16 at 50 microM and 100 microM inhibited palmitate oxidation by approximately 40% and 60%, respectively, pretreatment with both concentrations inhibited lipolysis in washed cells in an almost identical manner. The magnitude of inhibition increased with time of pretreatment. On the other hand, like inhibition of fatty acid oxidation, inhibition of lipolysis by Br-C4 pretreatment was dose-dependent with maximal inhibition reached after 3 h pretreatment. The finding that isoproterenol- and dibutyryl cAMP-stimulated lipolysis were similarly suppressed by either Br-C4 or Br-C16 pretreatment, suggesting that a step distal to cAMP formation was involved. In addition, while the inhibitory effect of Br-C16 was not significantly influenced, the inhibition of lipolysis caused by Br-C4 was attenuated by pretreating cells with crotonic acid, octanoate, or palmitate. The longer chain-length of the fatty acids the cells were exposed, the stronger attenuation of the inhibition caused by Br-C4 was observed. Moreover, whereas pretreatment with Br-C16 was without effect, pretreatment with Br-C4 significantly decreased hormone-sensitive lipase (HSL) activity in cell extracts, albeit to an extent much smaller than its inhibitory effect on lipolysis. In conclusion, these results indicate that irreversible inhibition of lipolysis by Br-C16 or Br-C4 cannot be attributed to their effect on fatty acid oxidation. Some factor capable of modulating HSL activity seems to be involved.

Somatostatin modulation of neurally mediated pepsinogen secretion from frog esophageal mucosa.

Frog esophageal mucosa contains peptic glands which are innervated by cholinergic neurons. When incubated in a medium containing 1.5 mM CaCl2, pepsinogen release from esophageal mucosa was increased by a high potassium concentration (55 mM KCl), 1,1-dimethyl-4-phenylpiperazinium (DMPP) or bethanechol. Whereas the response to bethanechol remained little changed, the response to high KCl concentrations or DMPP was abolished in the absence of Ca2+. The stimulatory effects of high KCl concentrations and DMPP were also eliminated by the presence of atropine or somatostatin. Furthermore, pepsinogen release in response to bethanechol was dose-dependently inhibited by somatostatin. Frog esophagus was found to contain somatostatin-like immunoreactivity, with a higher density at the end adjacent to the stomach. Chromatography of mucosa extract on Sephadex G-50 revealed a single peak of somatostatin-like immunoreactivity that coeluted with somatostatin-14. Immunohistochemical staining of the mucosa with peroxidase antiperoxidase technique demonstrated the presence of two varieties of somatostatin-like immunoreactivity-containing cells, one individually dispersed within the intercalated septa and the other in groups within the interlobular septa of the peptic glands. These results seem to indicate that somatostatin or somatostatin-like immunoreactivity may play a modulatory role in neurally mediated pepsinogen secretion in the frog esophagus.

Enhanced cyclic AMP responses in GH3 pituitary cells pretreated with muscarinic receptor agonists.

The effect of prolonged activation of cholinergic receptors on the subsequent cAMP responses in GH3 pituitary cells was examined. Whereas acetylcholine pretreatment had no effect on basal cAMP levels, it transiently enhanced vasoactive intestinal peptide-stimulated cAMP accumulation in the cells and this effect was abolished by atropine. Inclusion of eserine in the incubation medium, however, sustained and reinforced the enhancing effect of acetylcholine on forskolin-stimulated cAMP synthesis over 24 h. Similar enhancing effect was observed by oxotremorine or carbachol pretreatment. Furthermore, cAMP production in response to forskolin in the absence or presence of 3-isobutyl-1-methylxanthine was similarly augmented by acetylcholine pretreatment. The enhancement of forskolin-stimulated cAMP accumulation was arrested by pertussis toxin whether it was added before or during the oxotremorine pretreatment. Although cholera toxin pretreatment increased greatly the forskolin-stimulated cAMP levels, concomitant addition of oxotremorine was able to augment the response further in GH3 cells. In addition, cholera toxin- or pertussis toxin-catalysed ADP-ribosylation of G proteins as well as immunoreactive Gs alpha or Gi alpha levels in membranes obtained from oxotremorine-pretreated cells were not different from those from non-treated cells. Thus, the present study has demonstrated that continuous muscarinic receptor activation leads to increased adenylate cyclase activity in GH3 cells. Although a functional Gi/Go seems to be required for the development of this enhanced activity, neither Gi/Go nor Gs appears to be altered.

Endothelin-1 increases glucose transporter glut1 mRNA accumulation in 3T3-L1 adipocytes by a mitogen-activated protein kinase-dependent pathway.

The mechanism of enhancing glucose transport by prolonged endothelin-1 (ET-1) treatment of 3T3-L1 adipocytes was examined. Western and Northern blot analyses indicated that ET-1 increased the amount of both GLUT1 protein and mRNA. The degradation rate of GLUT1 mRNA as measured in the presence of actinomycin D, nevertheless, was not significantly altered by ET-1. Whereas various inhibitors for distinct signalling pathways were tested, only the mitogen-activated protein kinase (MAPK) kinase inhibitor, PD98059, was found to decrease significantly the enhancing effect of ET-1. Similar extent of inhibition was observed in cells pretreated with pertussis toxin (PT). Immunoblot analysis revealed that ET-1 may stimulate a transient phosphorylation of p42/p44 MAPK and both PT and PD98059 inhibited this stimulation. In addition, the effect of ET-1 on GLUT1 mRNA accumulation was inhibited by PD98059 and cycloheximide, implying that a trans-activation was involved. Taken together, these results suggest that ET-1 may induce GLUT1 gene expression by a MAPK-dependent mechanism.

Synergistic effect of arachidonic acid and cyclic AMP on glucose transport in 3T3-L1 adipocytes.

The combined effect of arachidonic acid and cAMP on glucose transport was examined in 3T3-L1 adipocytes. In cells pre-treated with arachidonic acid and increasing concentrations of 8-bromo cAMP for 8 h, although either agent alone enhanced glucose uptake, the simultaneous presence of both agents dramatically increased 2-deoxyglucose uptake in a synergistic fashion. Insulin-stimulated glucose transport, on the other hand, was only slightly affected. The synergistic effect of these two agents was abolished in the presence of cycloheximide. Immunoblot analysis revealed that the contents of ubiquitous glucose transporter (GLUT1) in total cellular and plasma membranes were similarly augmented in cells pre-treated with both arachidonic acid and 8-bromo cAMP, to a greater extent than the additive effect of each agent alone. The content of GLUT4, on the other hand, was not altered under the same experimental conditions. In cells pre-treated with 4beta-phorbol 12beta-myristate 13alpha-acetate (PMA) for 24 h to down-regulate protein kinase C (PKC), the subsequent synergistic effect of arachidonic acid and 8-bromo cAMP was greatly inhibited. In addition, pre-treatment with both PMA and 8-bromo cAMP enhanced glucose transport in a similarly synergistic fashion. Thus the present study seems to indicate that arachidonic acid may act with cAMP in a synergistic way to increase glucose transport by a PKC-dependent mechanism. The increased activity may be accounted for by increased GLUT1 synthesis.

Arachidonic acid stimulates the intrinsic activity of ubiquitous glucose transporter (GLUT1) in 3T3-L1 adipocytes by a protein kinase C-independent mechanism.

Exposure of adipocytes to arachidonic acid rapidly enhanced basal 2-deoxyglucose uptake, reaching maximal effect at approximately 8 hr. Insulin-stimulated 2-deoxyglucose uptake was not altered over the experimental period. While the short-term (2-h exposure) effect of arachidonic acid was negligibly influenced by cycloheximide, the enhancement of glucose transport by long-term (8-h) exposure to arachidonic acid was markedly decreased by the simultaneous presence of protein-synthesis inhibitors, implying that the short-term and long-term effects of arachidonic acid may involve distinct mechanisms. Immunoblot analysis revealed that 8-h but not 2-h exposure to arachidonic acid increased the content of the ubiquitous glucose transporter (GLUT1) in both total cellular and plasma membranes. The insulin-responsive glucose transporter (GLUT4), on the other hand, was not affected. Following 2-h exposure to arachidonic acid, kinetic studies indicated that the apparent Vmax of basal 2-deoxyglucose uptake was more than doubled, while the apparent Km for 2-deoxyglucose remained unchanged. Protein kinase C (PKC) depletion by pretreating cells with 4 beta-phorbol 12 beta-myristate 13 alpha-acetate (PMA) for 24 h had little influence on the subsequent enhancing effect of arachidonic acid on 2-deoxyglucose uptake. In addition, PMA was able to stimulate 2-deoxyglucose uptake in arachidonic-acid-pretreated cells with similar increments as in non-treated cells. Thus, our data seem to suggest that arachidonic acid may enhance the intrinsic activity of GLUT1 by a PKC-independent mechanism.

Potentiation of thyrotropin-releasing hormone-stimulated prolactin mRNA levels in GH3 cells by acetylcholine.

We have examined the effect of acetylcholine (ACh) pretreatment on the thyrotropin-releasing hormone (TRH) induced prolactin gene expression in GH3 cells, a rat pituitary tumor cell line. Prolonged exposure (greater than 6 h) to ACh enhanced the TRH-induced prolactin mRNA accumulation in a time- and concentration-dependent manner while ACh by itself did not affect the basal prolactin mRNA levels appreciably. Maximal augmentation of the TRH-induced prolactin mRNA accumulation was obtained when cells were pretreated with 10(-5) M ACh for 24 h. The activation was mimicked by carbachol and oxotremorine and was blocked by the simultaneous presence of atropine. Preincubation of GH3 cells with pertussis toxin abolished the augmenting effect of ACh. These results indicate that prolonged exposure to muscarinic receptor agonists may enhance the TRH-stimulated prolactin mRNA expression and a pertussis toxin sensitive G-protein may be involved.

Somatostatin inhibits pepsinogen secretion via a cyclic AMP-independent pathway.

Frog esophageal mucosa contains peptide glands which release pepsinogen in response to a variety of secretagogues and serves as a model to examine the inhibitory action of somatostatin. The pepsinogen secretion in response to bethanechol was inhibited by somatostatin in a noncompetitive fashion. The maximal response induced by bethanechol was reduced and the EC50 for bethanechol was increased in the presence of somatostatin. On the other hand, somatostatin showed essentially no effect on pepsinogen release evoked by ionophore A23187, dibutyryl cAMP or by forskolin in the presence of atropine. Atropine was included in the incubation mixture to eliminate the effect of acetylcholine released by forskolin from the intrinsic cholinergic neurons also present in the mucosa. Somatostatin did not exert any significant effect on the basal or the forskolin-stimulated cAMP accumulation in the mucosa, nor the basal or the forskolin-stimulated adenylate cyclase activity in the membranes of the peptic cells isolated from the mucosa. Thus, these results seem to suggest that somatostatin inhibits pepsinogen secretion from frog esophageal mucosa by a cAMP-independent pathway.

The effect of GTP on benzodiazepine receptors.

GTP decreases the specific binding of [3H]flunitrazepam to cerebral cortical membrane sites. Scatchard analysis data show that GTP does not alter the maximum binding sites (Bmax), but increases the dissociation constant (KD) for [3H]flunitrazepam. GTP also inhibits the specific binding of the benzodiazepine antagonist [3H]CGS-8216. The specific binding of [3H]CGS-8216 displaceable by clonazepam is inhibited to a greater extent by GTP than that displaceable by the benzodiazepine antagonists, CGS-8216 or beta-CCE.

Pharmacokinetics of norethindrone: effect of particle size.

In 24 healthy women between the ages of 19 and 35 years who had not used oral contraceptive preparations for at least 60 days, it was found that the smaller the particle size of norethindrone (NET) administered, the higher was the plasma NET level obtained. Three different preparations having particle sizes of NET smaller than 250 microns, 44 microns or 10 microns were tested in a crossover pattern. The time required to reach maximum plasma concentration (Tmax) became shorter with decreasing particle size, 1.69 hr, 1.52 hr and 1.06 hr, respectively. As particle size was reduced, the maximum NET plasma concentration (Cmax) increased for the 3 different 1 mg NET preparations, i.e. 8.66 ng/ml, 10.53 ng/ml and 15.73 ng/ml. A trial with a 2 mg NET preparation made with NET utilizing the 44 microns same material displayed a Tmax similar to the 1 mg NET preparation having the same particle size while the Cmax reached a level of 17.56 ng/ml. The area under the plasma concentration versus time curve from 0-24 hrs and the extrapolated total area under the curve, increased with decreasing particle size. The use of a smaller particle size allows for more rapid dissolution or oral contraceptive tablets when measured in vitro; however, there is no evidence that such faster dissolution leads to a significant difference in efficacy. Oral contraceptive tablets have, since their inception, utilized both large and small NET particle size material in various preparations.

Calcium buffering capacity of human seminal plasma: the role of EGTA in stimulating sperm motility.

The role of EGTA in stimulating human sperm motility (reported in Lancet i: 460-461, 1984) was investigated by measuring the calcium buffering capacity of human seminal plasma. Human seminal plasma contains 9.5 +/- 1.1 mM (mean +/- SE) calcium of which 0.16 +/- 0.01 mM only exists as free Ca2+. The free Ca2+ concentration was not changed by the addition of either 1 mM CaCl2 or 1 mM EGTA. The ability of seminal plasma to bind calcium ions was determined by adding varying amounts of CaCl2. Scatchard analysis of the results indicates the presence of high amounts of high-affinity (Kd1 = 3.4 +/- 0.2 microM, Bm1 = 11.5 +/- 1.5 mM) and low-affinity (Kd2 = 0.55 +/- 0.04 mM, Bm2 = 30.4 +/- 1.7 mM) Ca2+-complexing agents. The low-affinity Ca2+-binding substance may be citrate. These results seem to suggest that human seminal plasma has a high Ca2+ buffering capacity and the stimulation of sperm motility by EGTA ought to be mediated via a mechanism other than the reduction of the free calcium concentration in semen.

Effects of crude drugs on glucose uptake in 3T3-L1 adipocytes.

In this study, various water-extracted crude drugs from Radix Asparagi, Radix Ginseng, Radix Scutellariae, Cortex Lycii Radicis, Cortex Phellodendri and Radix Ophiopogonis were investigated in their effects on [3H]-2-deoxyglucose uptake in 3T3-L1 adipocytes. Following treatment of cells with various crude drugs for 60 mim, the basal [3H]-2-deoxyglucose uptake in cultured 3T3-L1 cells was changed by Radix Asparagi from 140 pmole/min/mg protein of control to 513 (0.1 mg/ml), 201 (1 mg/ml) and 97 (10 mg/ml). Glucose uptake was changed to 324 (0.1 mg/ml), 146 (1 mg/ml) and 46 (10 mg/ml) with Radix Ginseng. In the presence of Radix Scutellariae, glucose uptake was changed to 215 (0.1 mg/ml), 213 (1 mg/ml) and 34 (10 mg/ml). In the presence of Cortex Lycii Radicis, glucose uptake was 230 (0.1 mg/ml), 188 (1 mg/ml) and 38 (10 mg/ml). In the case of Cortex Phellodendri and Radix Ophiopogonis, uptake was changed to 142 (0.1 mg/ml), 132 (1 mg/ml), 24 (10 mg/ml) and 489 (0.1 mg/ml), 374 (1 mg/ml), 344 (10 mg/ml), respectively. In insulin-stimulated cells, the [3H]-2-deoxyglucose uptake was changed by Radix Asparagi from 570 pmole/min/mg protein of the control to 816 (0.1 mg/ml), 674 (1 mg/ml) and 532 (10 mg/ml). After incubation with Radix Ginseng, the glucose uptake was changed to 254 (0.1 mg/mi), 123 (1 mg/mi) to 76 (10 mg/mi). In the presence of Radix Scutellariae, the glucose uptake was changed to 315 (0.1 mg/ml), 265 (1 mg/ml) and 33 (10 mg/ml). After incubation of Cortex Lycii Radicis, the uptake activity was changed to 281 (0.1 mg/ml), 248 (1 mg/ml) and 37 (10 mg/ml). In the case of Cortex Phellodendri and Radix Ophiopogonis, the activity of glucose uptake was measured as 747 (0.1 mg/ml), 523 (1 mg/ml), 33 (10 mg/ml) and 753 (0.1 mg/ml), 740 (1 mg/ml), and 421 (10 mg/ml), respectively. These results indicate that the water-extracted materials of Radix Asparagi and Radix Ophiopogonis increase the glucose uptake in basal and insulin-stimulated 3T3-L1 adipocytes.

Effects of antiglaucoma drugs and corticosteroids on the cellular glucose uptake in cultured porcine corneal endothelial cells.

In this study, various commercially used antiglaucoma drugs and corticosteroids were investigated in their effects on porcine corneal endothelial cells especially in cellular glucose uptake. Cellular glucose uptake directly affects the pumping efficiency in corneal endothelial cells. Following the cells' treatment with various antiglaucoma eyedrops for 100 min, the 3H-2-deoxyglucose uptake in cultured porcine corneal endothelial cells was affected by betaxolol from 3.1% (1.6 mM), 181% (0.16 mM) to 158% (0.016 mM), by timolol from 93% (0.79 mM), 227% (0.079 mM) to 151% (0.0079 mM), by carteolol from 141% (3.4 mM), 180% (0.34 mM) to 97% (0.034 mM), by levobunolol from 80% (1.5 mM), 98% (0.15 mM) to 90% (0.015 mM), by dipivefrin from 116% (0.2 mM), 176% (0.02 mM) to 108% (0.002 mM) and by pilocarpine from 115% (9.6 mM), 210% (0.96 mM) to 210% (0.096 mM) when the cells were compared with a control medium. In the presence of various corticosteroids, the glucose uptake in corneal endothelial cells was affected by fluorometholone from 160% (0.26 mM), 139% (0.026 mM) to 107% (0.0026 mM), by dexamethasone from 85% (0.25 mM), 117% (0.025 mM) to 109% (0.0025 mM) and by betamethasone from 95% (0.25 mM), 96% (0.025 mM) to 99% (0.0025 mM). These results show that the commercial eyedrops of antiglaucoma drugs and corticosteroids will not decrease the cellular glucose uptake in cultured porcine corneal endothelial cells except when incubated with high concentrations of betaxolol, levobunolol and dexamethasone.

Alteration of glucose uptake in cultured human corneal endothelial cells grown in high glucose media via cAMP-dependent pathway.

In this study, cultured human corneal endothelial cells were incubated in media containing various concentrations of glucose at 5 mM, 10 mM, and 25 mM for 2 days. Then, the cellular 2-deoxyglucose uptake and cAMP concentration of cultured human corneal endothelial cells were measured. The results indicated that the activity of cellular glucose uptake of nmole/min/mg protein was decreased gradually from 0.18 (5 mM), 0.10 (10 mM), 0.07 (20 mM) to 0.06 (25 mM) after 2 days incubation with a high concentration of glucose. The glucose uptake in insulin-treated human corneal endothelial cells also exhibited a similar declining effect in high glucose media from 0.30 (5 mM), 0.11 (10 mM), 0.08 (20 mM) to 0.05 (25 mM). The cAMP concentration in human corneal endothelial cells was measured in the presence of high glucose media. It was indicated that the cAMP concentrations of pmole/well in both insulin-treated and non-insulin treated cells were also decreased after increasing the glucose concentration in the media from 73 (5 mM) to 20 (25 mM) and 101 (5 mM) respectively. The cAMP concentration in insulin-treated cells was less than in non-insulin treated cells. This decreasing effect was significantly reversed by the addition of 1 mM dibutyryl-cAMP to the cells for 1 hour in both groups. These results suggest that the diabetic state may decrease the 2-deoxyglucose uptake in human corneal endothelial cells via cAMP-dependent pathway.