Temporal Trends in the Epidemiology of HIV in Turkey

OBJECTIVE

The aim of this study was to analyze the temporal trends of HIV epidemiology in Turkey from 2011 to 2016.

METHODS

Thirty-four teams from 28 centers at 17 different cities participated in this retrospective study. Participating centers were asked to complete a structured form containing questions about epidemiologic, demographic and clinical characteristics of patients presented with new HIV diagnosis between 2011 and 2016. Demographic data from all centers (complete or partial) were included in the analyses. For the cascade of care analysis, 15 centers that provided full data from 2011 to 2016 were included. Overall and annual distributions of the data were calculated as percentages and the Chi square test was used to determine temporal changes.

RESULTS

A total of 2,953 patients between 2011 and 2016 were included. Overall male to female ratio was 5:1 with a significant increase in the number of male cases from 2011 to 2016 (p<0.001). The highest prevalence was among those aged 25-34 years followed by the 35-44 age bracket. The most common reason for HIV testing was illness (35%). While the frequency of sex among men who have sex with men increased from 16% to 30.6% (p<0.001) over the study period, heterosexual intercourse (53%) was found to be the most common transmission route. Overall, 29% of the cases presented with a CD4 count of >500 cells/mm3 while 46.7% presented with a CD4 T cell count of <350 cells/mm3. Among newly diagnosed cases, 79% were retained in care, and all such cases initiated ART with 73% achieving viral suppression after six months of antiretroviral therapy.

CONCLUSION

The epidemiologic profile of HIV infected individuals is changing rapidly in Turkey with an increasing trend in the number of newly diagnosed people disclosing themselves as MSM. New diagnoses were mostly at a young age. The late diagnosis was found to be a challenging issue. Despite the unavailability of data for the first 90, Turkey is close to the last two steps of 90-90-90 targets.

Native High-Density Lipoprotein and Melatonin Improve Platelet Response Induced by Glycated Lipoproteins

Activated platelets and glycated lipoproteins are responsible for atherothrombosis in diabetics. Melatonin and native high-density lipoproteins are crucial in the preservation of pro/oxidant-antioxidant balance. The aim of the present study was to investigate the in vitro effects of native high-density lipoproteins and melatonin on altering the platelet response induced by glycated lipoproteins. Low-density lipoproteins and high-density lipoproteins were purified from plasma by ultracentrifugation and were glycated with glucose for three weeks. After incubation with or without melatonin/or native highdensity lipoproteins, low-density lipoproteins, glycated low-density lipoproteins/glycated high-density lipoproteins were added to ADP-induced platelets. Oxidative parameters, caspase-3/9 and nitric oxide levels were measured spectrophotometrically; CD62-P/ annexin-V expression was determined by flow cytometry. In glycated low-density lipoprotein/glycated high-density lipoprotein-treated groups, platelet malondialdehyde/ protein carbonyl, P-selectin, annexin-V, caspase-3/9 levels were increased (ranging from P < 0.001 to P < 0.01); glutathione and nitric oxide levels were reduced (ranging from P < 0.001 to P < 0.01). In glycated low-density lipoprotein/glycated high-density lipoprotein-treated groups, melatonin treatment reduced malondialdehyde, protein carbonyl, CD62-P, annexin-V and caspase-3/9 (P < 0.001, P < 0.01) levels and elevated nitric oxide (only glycated low-density lipoproteins). In glycated low-density lipoprotein/glycated high-density lipoprotein-treated groups, native high-density lipoprotein treatment reduced malondialdehyde, protein carbonyl, annexin-V, caspase-3/9 levels (P < 0.001, P < 0.01) and increased glutathione; nitric oxide levels (only with gly-HDL). Both melatonin and high-density lipoproteins should be regarded as novel promising mechanism-based potential therapeutic targets to prevent atherothrombosis in diabetics.

Hydrogen Sulfide Protects Renal Grafts Against Prolonged Cold Ischemia-Reperfusion Injury via Specific Mitochondrial Actions

Ischemia-reperfusion injury is unavoidably caused by loss and subsequent restoration of blood flow during organ procurement, and prolonged ischemia-reperfusion injury IRI results in increased rates of delayed graft function and early graft loss. The endogenously produced gasotransmitter, hydrogen sulfide (H₂ S), is a novel molecule that mitigates hypoxic tissue injury. The current study investigates the protective mitochondrial effects of H₂ S during in vivo cold storage and subsequent renal transplantation (RTx) and in vitro cold hypoxic renal injury. Donor allografts from Brown Norway rats treated with University of Wisconsin (UW) solution + H₂ S (150 μM NaSH) during prolonged (24-h) cold (4°C) storage exhibited significantly (p < 0.05) decreased acute necrotic/apoptotic injury and significantly (p < 0.05) improved function and recipient Lewis rat survival compared to UW solution alone. Treatment of rat kidney epithelial cells (NRK-52E) with the mitochondrial-targeted H₂ S donor, AP39, during in vitro cold hypoxic injury improved the protective capacity of H₂ S >1000-fold compared to similar levels of the nonspecific H₂ S donor, GYY4137 and also improved syngraft function and survival following prolonged cold storage compared to UW solution. H₂ S treatment mitigates cold IRI-associated renal injury via mitochondrial actions and could represent a novel therapeutic strategy to minimize the detrimental clinical outcomes of prolonged cold IRI during RTx.

Effects of vitamin D on insulin secretion and glucose transporter GLUT2 under static magnetic field in rat

The present study investigated the effects of vitamin D supplementation on insulin secretion and glucose transporter following static magnetic field (SMF) exposure in rat. Wistar male rats were divided into the following groups: control, SMF-exposed rat (128 mT; 1 h/day for 5 days), vitamin D-treated rats (1600 IU/100 g, received by gavage for five consecutive days), and co-exposed rats (the last day and after exposure rats received a single dose of vitamin D per os). Our results showed that exposure to SMF induced an increase in plasma glucose level and a decrease in plasma insulin concentration. Moreover, β cell insulin content and islet area were lower in SMF-exposed group compared to control. Likewise, we reported the absence of GLUT2 expression in extracellular membrane of pancreatic islet in SMF-exposed group. Interestingly, supplementation with single dose of vitamin D per os corrected insulinemia and glycemia disturbances caused by SMF. By contrast, the same treatment failed to correct pancreatic area. This study provides evidence that vitamin D supplementation has curative effect on pancreas insulin content and on GLUT2 disruption caused by SMF exposure.

The features of infectious diseases departments and anti-infective practices in France and Turkey: a cross-sectional study

The aim of this study was to assess the infectious diseases (ID) wards of tertiary hospitals in France and Turkey for technical capacity, infection control, characteristics of patients, infections, infecting organisms, and therapeutic approaches. This cross-sectional study was carried out on a single day on one of the weekdays of June 17-21, 2013. Overall, 36 ID departments from Turkey (n = 21) and France (n = 15) were involved. On the study day, 273 patients were hospitalized in Turkish and 324 patients were followed in French ID departments. The numbers of patients and beds in the hospitals, and presence of an intensive care unit (ICU) room in the ID ward was not different in both France and Turkey. Bed occupancy in the ID ward, single rooms, and negative pressure rooms were significantly higher in France. The presence of a laboratory inside the ID ward was more common in Turkish ID wards. The configuration of infection control committees, and their qualifications and surveillance types were quite similar in both countries. Although differences existed based on epidemiology, the distribution of infections were uniform on both sides. In Turkey, anti-Gram-positive agents, carbapenems, and tigecycline, and in France, cephalosporins, penicillins, aminoglycosides, and metronidazole were more frequently preferred. Enteric Gram-negatives and hepatitis B and C were more frequent in Turkey, while human immunodeficiency virus (HIV) and streptococci were more common in France (p < 0.05 for all significances). Various differences and similarities existed in France and Turkey in the ID wards. However, the current scene is that ID are managed with high standards in both countries.

Update on treatment options for spinal brucellosis

We evaluated the efficacy and tolerability of antibiotic regimens and optimal duration of therapy in complicated and uncomplicated forms of spinal brucellosis. This is a multicentre, retrospective and comparative study involving a total of 293 patients with spinal brucellosis from 19 health institutions. Comparison of complicated and uncomplicated spinal brucellosis was statistically analysed. Complicated spinal brucellosis was diagnosed in 78 (26.6%) of our patients. Clinical presentation was found to be significantly more acute, with fever and weight loss, in patients in the complicated group. They had significantly higher leukocyte and platelet counts, erythrocyte sedimentation rates and C-reactive protein levels, and lower haemoglobulin levels. The involvement of the thoracic spine was significantly more frequent in complicated cases. Spondylodiscitis was complicated, with paravertebral abscess in 38 (13.0%), prevertebral abscess in 13 (4.4%), epidural abscess in 30 (10.2%), psoas abscess in 10 (3.4%) and radiculitis in 8 (2.7%) patients. The five major combination regimens were: doxycycline 200 mg/day, rifampicin 600 mg/day and streptomycin 1 g/day; doxycycline 200 mg/day, rifampicin 600 mg/day and gentamicin 5 mg/kg; doxycycline 200 mg/day and rifampicin 600 mg/day; doxycycline 200 mg/day and streptomycin 1 g/day; and doxycycline 200 mg/day, rifampicin 600 mg/day and ciprofloxacin 1 g/day. There were no significant therapeutic differences between these antibiotic groups; the results were similar regarding the complicated and uncomplicated groups. Patients were mostly treated with doxycycline and rifampicin with or without an aminoglycoside. In the former subgroup, complicated cases received antibiotics for a longer duration than uncomplicated cases. Early recognition of complicated cases is critical in preventing devastating complications. Antimicrobial treatment should be prolonged in complicated spinal brucellosis in particular.

In vitro effects of nitric oxide donors on apoptosis and oxidative/nitrative protein modifications in ADP-activated platelets

Nitric oxide (NO) is an important physiological signaling molecule. However, when produced in excessive amounts, NO can also have toxic effects. The aim of this study is to investigate the effects of exogenous- and endogenous-derived NO on oxidative modifications of proteins and apoptosis in activated platelets. Washed platelets were incubated with L-arginine or nitroso-glutathione (GSNO) in the presence of adenosine diphosphate (ADP). After incubation, caspase-3 activity, phosphatidylserine (PS) externalization and the potential of mitochondrial membrane as markers of apoptosis were measured. In addition, the alterations in protein carbonylation (PCO) and nitrotyrosine (NT) formation as markers of protein oxidation were examined. Platelet activation with ADP (20 µM) significantly increased PCO and NT levels and apoptotic events. After incubation with L-arginine, platelet NO production increased significantly. This L-arginine-induced increase caused decreases in formerly increased PCO and NT levels associated with ADP-induced platelet activation. Stimulation of NO production with L-arginine protected platelets from apoptosis. GSNO caused an increase in protein NT levels. Despite this change, GSNO was effective in inhibition of P-selectin expression, platelet aggregation, protein carbonylation and apoptosis. The results suggest that L-arginine and GSNO-mediated NO leads to the inhibition of key apoptotic processes including caspase-3 activation, PS exposure and low mitochondrial membrane potential in washed platelets. The inhibitory effect of platelet clearance of L-arginine and GSNO may be a novel useful therapeutic property in clinical application.

Glycerol metabolism alteration in adipocytes from n3-PUFA-depleted rats, an animal model for metabolic syndrome

Aquaglyceroporin 7 (AQP7) is a glycerol transporter expressed in adipocytes. Its expression has been shown to be modulated in obesity. Metabolic syndrome is characterized by abdominal obesity, insulin resistance, dyslipidemia, and hypertension. An animal model displaying several features of metabolic syndrome was used to study the AQP7 expression at both mRNA and protein level and glycerol flux in adipocytes. Second generation n3-PUFA depleted female rats is a good animal model for metabolic syndrome as it displays characteristic features such as liver steatosis, visceral obesity, and insulin resistance. Our data show a reduced expression of AQP7 at the protein level in adipose tissue from n3-PUFA-depleted rats, without any changes at the mRNA levels. [U-(14)C]-Glycerol uptake was not modified in adipocytes from n3-PUFA-depleted animals.

Influence of platelet γ-glutamyltransferase on oxidative stress and apoptosis in the presence of holo-transferrin

Several studies have documented that formation of oxidant mediators may induce apoptosis in nucleated and anucleated cells by modulating intracellular signalling pathways. Reactive oxygen species (ROS) play a very important role in the platelet function. γ-Glutamyltransferase (GGT), a novel source of cellular production of oxidants in the presence of iron and reduced glutathione (GSH), is also found on platelets. The role of platelet-bound GGT in platelet apoptosis and oxidative stress is unknown. The aim of our study was to determine the effects of platelet GGT activity on oxidative stress and apoptotic events in vitro via determination of lipid peroxidation (LPO), protein oxidation, GSH, catalase, caspase-3 activation and phosphatidylserine (PS) exposure in the presence of holo-transferrin (Tf). Stimulation of platelet GGT activity with GSH and glycylglycine (GlyGly) increased caspase-3 activation and PS exposure. A significant increase in lipid and protein oxidation and decrease in GSH and catalase levels was also observed in platelets with stimulation of GGT activity in the presence of Tf. Inhibition of GGT activity effectively reduced all the markers. These results suggest that generation of ROS by the GGT/GSH/Tf system can modify the platelets' redox environment and induce apoptosis in in vitro conditions.

Does NAD(P)H oxidase-derived H2O2 participate in hypotonicity-induced insulin release by activating VRAC in β-cells?

NAD(P)H oxidase (NOX)-derived H(2)O(2) was recently proposed to act, in several cells, as the signal mediating the activation of volume-regulated anion channels (VRAC) under a variety of physiological conditions. The present study aims at investigating whether a similar situation prevails in insulin-secreting BRIN-BD11 and rat β-cells. Exogenous H(2)O(2) (100 to 200 μM) at basal glucose concentration (1.1 to 2.8 mM) stimulated insulin secretion. The inhibitor of VRAC, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) inhibited the secretory response to exogenous H(2)O(2). In patch clamp experiments, exogenous H(2)O(2) was observed to stimulate NPPB-sensitive anion channel activity, which induced cell membrane depolarization. Exposure of the BRIN-BD11 cells to a hypotonic medium caused a detectable increase in intracellular level of reactive oxygen species (ROS) that was abolished by diphenyleneiodonium chloride (DPI), a universal NOX inhibitor. NOX inhibitors such as DPI and plumbagin nearly totally inhibited insulin release provoked by exposure of the BRIN-BD11 cells to a hypotonic medium. Preincubation with two other drugs also abolished hypotonicity-induced insulin release and reduced basal insulin output: 1) N-acetyl-L-cysteine (NAC), a glutathione precursor that serves as general antioxidant and 2) betulinic acid a compound that almost totally abolished NOX4 expression. As NPPB, each of these inhibitors (DPI, plumbagin, preincubation with NAC or betulinic acid) strongly reduced the volume regulatory decrease observed following a hypotonic shock, providing an independent proof that VRAC activation is mediated by H(2)O(2). Taken together, these data suggest that NOX-derived H(2)O(2) plays a key role in the insulin secretory response of BRIN-BD11 and native β-cells to extracellular hypotonicity.

Memory T-cell predominance following T-cell depletional therapy derives from homeostatic expansion of naive T cells

T-cell depletion reportedly leads to alterations in the T-cell compartment with predominant survival of memory phenotype CD4 T cells. Here, we asked whether the prevalence of memory T cells postdepletion results from their inherent resistance to depletion and/or to the homeostatic expansion of naive T cells and their phenotypic conversion to memory, which is known to occur in lymphopenic conditions. Using a 'mosaic memory' mouse model with trackable populations of alloreactive memory T cells, we found that treatment with murine antithymocyte globulin (mATG) or antilymphocyte serum (ALS) effectively depleted alloreactive memory CD4 T cells, followed by rapid homeostatic proliferation of endogenous CD4 T cells peaking at 4 days postdepletion, with no homeostatic advantage to the antigen-specific memory population. Interestingly, naive (CD44lo) CD4 T cells exhibited the greatest increase in homeostatic proliferation following mATG treatment, divided more extensively compared to memory (CD44hi) CD4 T cells and converted to a memory phenotype. Our results provide novel evidence that memory CD4 T cells are susceptible to lymphodepletion and that the postdepletional T-cell compartment is repopulated to a significant extent by homeostatically expanded naive T cells in a mouse model, with important important implications for immune alterations triggered by induction therapy.

Functional role of aquaglyceroporin 7 expression in the pancreatic beta-cell line BRIN-BD11

Both mouse and rat pancreatic islet beta-cells were recently found to express aquaglyceroporin 7 (AQP7). In the present study, the expression and role of AQP7 in the function of BRIN-BD11 cells were investigated. AQP7 mRNA and protein were detected by RT-PCR and Western blot analysis, respectively. In an isoosmolar medium, the net uptake of [2-(3)H]glycerol displayed an exponential time course reaching an equilibrium plateau value close to its extracellular concentration. Within 2 min of incubation in a hypotonic medium (caused by a 50 mM decrease in NaCl concentration), the [2-(3)H]glycerol uptake averaged 143.2 +/- 3.8% (n = 24; P < 0.001) of its control value in isotonic medium, declining thereafter consistently with previously demonstrated volume regulatory decrease. When isoosmolarity was restored by the addition of 100 mM urea to the hypotonic medium, [2-(3)H]glycerol uptake remained higher (112.1 +/- 2.8%, n = 24; P < 0.001) than its matched control under isotonic conditions, indicating rapid entry of urea and water. Insulin release by BRIN-BD11 cells was 3 times higher in hypotonic than in isotonic medium. When glycerol (100 mM) or urea (100 mM) were incorporated in the hypotonic medium, the insulin release remained significantly higher than that found in the control isotonic medium, averaging respectively 120.2 +/- 4.2 and 107.0 +/- 3.8% of the paired value recorded in the hypotonic medium. These findings document the rapid entry of glycerol and urea in BRIN-BD11 cells, likely mediated by AQP7.

Oxidized-LDL and Fe3+/ascorbic acid-induced oxidative modifications and phosphatidylserine exposure in human platelets are reduced by melatonin

Low-density lipoprotein (LDL) modifications and platelet activation are major risk factors for cardiovascular diseases. When platelets are exposed to oxidative stress, they become activated. Oxidized LDL (ox-LDL) and metal-catalysed oxidation systems such as Fe3+/ascorbic acid increase free radical production. We wanted to verify whether melatonin has a protective effect against oxidative modifications and phosphatidylserine externalization in platelets induced by ox-LDL and Fe3+/ascorbic acid. For in vitro effects of melatonin on platelets, ADP-activated platelets were incubated with ox-LDL or Fe3+/ascorbic acid for 1 h at 37 degrees C with or without melatonin. Then platelet malondialdehyde, protein carbonyl and glutathione levels were measured. Platelet phosphatidylserine exposure was measured with annexin-V using flow cytometry. Malondialdehyde, protein carbonyl and phosphatidylserine levels of platelets treated with Fe3+/ascorbic acid significantly increased compared to the control group. Glutathione contents of Fe3+/ascorbic acid-treated platelets significantly decreased. Melatonin pre-treatment of Fe3+/ascorbic acid-treated platelets caused a mar ked reduction in malondialdehyde and phosphatidylserine levels and a marked increase in glutathione levels. Melatonin also caused non-significant reduction in protein carbonyl contents of Fe3+/ascorbic acid-treated platelets. Malondialdehyde, protein carbonyl and phosphatidylserine levels of platelets treated with ox-LDL also significantly increased compared to the control group. Platelet glutathione levels non-significantly decreased with ox-LDL. With addition of melatonin, malondialdehyde, protein carbonyl and phosphatidylserine levels of platelets treated with ox-LDL significantly decreased. These data suggest that melatonin may protect platelets from iron overload-induced and ox-LDL-induced oxidative modifications and also from the triggering signals of apoptosis activation, possibly due to its scavenger effect on toxic free radicals.

Glucose intolerance associated to insulin resistance and increased insulin secretion in rats depleted in long-chain omega3 fatty acids

An intragastric D-glucose tolerance test was performed, after overnight starvation, in female rats depleted in long-chain polyunsaturated omega3 fatty acids (omega3D rats) and control rats of same age and gender. The plasma D-glucose and insulin concentrations, insulinogenic index, and HOMA for insulin resistance were all higher, after overnight starvation, in omega3D rats than in control animals. Over the 120-minute period following the intragastric administration of D-glucose, the area under the curve for the same four variables was also higher in omega3D rats than in control animals. In addition to visceral obesity, liver steatosis, hypertension, and cardiac hypertrophy, the omega3D rats thus display further features of the metabolic syndrome, namely glucose intolerance and insulin resistance, despite hyperinsulinemia.

Rapid effects of the intravenous injection of a medium-chain triglyceride: fish oil emulsion on the triglyceride fatty acid pattern of soleus muscle from omega3 fatty acid-depleted rats

Second generation rats depleted in long-chain polyunsaturated omega3 fatty acids display several features of the metabolic syndrome, including visceral obesity, liver steatosis, insulin resistance, hypertension, and cardiac hypertrophy. In the framework of an extensive study on such metabolic, hormonal and functional perturbations, the phospholipid fatty acid pattern and ex vivo metabolism of D-glucose were recently investigated in the soleus muscle of these omega3-depleted rats. The present study deals with the triglyceride fatty acid content and pattern of the soleus muscle in control animals and omega3-depleted rats. Some of the latter rats were injected intravenously 60-120 minutes before sacrifice with either an omega3 fatty acid-rich medium-chain triglyceride/fish oil emulsion (omega3-FO rats) or a control medium-chain triglyceride/olive oil emulsion (omega3-OO rats). The total fatty acid content of triglycerides was comparable in control and omega3-depleted rats and, in both cases, inversely related to their C20:4omega6 relative content. At variance with the situation found in control rats, no long-chain polyunsaturated omega3 fatty acid (C18:3omega3, C20:5omega3, C22:5omega3, C22:6omega3) was detected in the omega3-depleted rats. Unexpectedly, the triglyceride content in most long-chain polyunsaturated omega6 fatty acids (C18:2omega6, C20:3omega6, C20:4omega6 and C22:4omega6) had also decreased in the latter rats. Moreover, the activity of Delta9-desaturase was apparently increased in the omega3-depleted rats, as judged from the C16:1omega7/C16:0 and C18:1omega9/C18:0 ratios. The omega3-FO rats differed from omega3-OO rats by a lower contribution of C18:2omega6 metabolites (C18:3omega6, C20:3omega6, C20:4omega6 and C22:4omega6). These findings indicate that the prior injection of the medium-chain triglyceride/fish oil emulsion, known to increase the muscle phospholipid content in long-chain polyunsaturated omega3 fatty acids, may nevertheless accentuate the depletion in long-chain polyunsaturated omega6 fatty acids otherwise found in the triglycerides of omega3-depleted rats. Such a dual effect is reminiscent of that observed, under the same experimental conditions, for selected variables in D-glucose metabolism in the soleus muscle.

Life satisfaction and leisure activities during men's retirement: a Turkish sample

This study was planned and carried out as a pilot study to determine the life satisfaction of men from the Official Social Security Institutions in Turkey (n = 231). The Life Satisfaction Index was used as the measure. Among this group of retired men, the most popular leisure activities were audio-visual and reading. The strongest predictor of life satisfaction was the frequency of participation in leisure activities, followed by the level of satisfaction with health, income, and planning of leisure activities.

Alteration of adipocyte metabolism in omega3 fatty acid-depleted rats

Presently an insufficient supply of long-chain polyunsaturated omega3 fatty acid is prevalent in Western populations leading to potential metabolic consequences. Based on this fact, this study deals mainly with various aspects of lipid metabolism in second generation female omega3-depleted rats. The parametrial fat and body weights were higher in omega3-depleted than control animals. This coincided with liver steatosis but did not alter heart triglyceride/phospholipid ratio. The net uptake of [U-14C] palmitate by adipocytes was also higher in omega3-depleted rats than in control animals. The uptake of D-[U- 4C] glucose or [1,2 (-14)C] acetate by adipocytes was lower, however in omega3-depleted than control animals and was unaffected by insulin in the former as distinct from latter animals. Despite comparable basal lipolysis, the increase in glycerol output from adipocytes provoked by theophylline was higher in omega3-depleted than control rats. The fatty acid pattern of lipids in adipose tissue was characterized in the omega3-depleted rats by a much lower omega3 content, higher apparent Delta 9-saturase and elongase activities, lower efficiency for the conversion of C18:2omega6 to C20:4omega6 and higher efficiency for the conversion of C18:3omega3 to C20:5omega3. These features were compared to those prevailing in liver and plasma lipids. The present study thus extends knowledge on the alteration of lipid metabolism resulting from a deficiency in long-chain polyunsaturated omega3 fatty acids.

Rapid changes in liver lipid composition and pancreatic islet K+ handling and secretory behaviour provoked by the intravenous administration of a medium-chain triglyceride: fish oil emulsion to long-chain polyunsaturated omega3 fatty acid-depleted rats

Second generation rats depleted in long-chain polyunsaturated omega3 fatty acids are currently used as an animal model for the insufficient dietary supply of such fatty acids often prevailing in Western populations. The present study deals mainly with the effects of a novel medium-chain triglyceride: fish oil emulsion (MCT:FO), as compared to a control medium-chain triglyceride:olive oil emulsion (MCT: OO), administered as an intravenous bolus to the omega3-depleted rats 60-120 min before sacrifice upon selected biochemical and biophysical variables. The major findings consisted of a severe decrease of the omega3 fatty acid content of liver lipids in non-injected omega3-depleted rats and its partial correction after injection of the MCT:FO emulsion. The omega3-depleted rats also displayed liver steatosis, increased incorporation of long-chain polyunsaturated omega6 fatty acids in liver phospholipids and increased activity of liver Delta9-desaturase. As judged from the effects of ouabain upon 86Rb net uptake by isolated pancreatic islets, the activity of Na+,K+-ATPase was virtually abolished in the omega3-depleted rats. The latter defect was corrected by prior intravenous injection of the MCT:FO emulsion, this coinciding with suppression of the excessive secretory response to a number of insulin secretagogues otherwise observed in the islets of omega3-depleted rats injected or not with the MCT:OO emulsion.

The effect of exercise on urinary gamma-glutamyl transferase and protein levels of volleyball players

AIM

Postexercise proteinuria and increased urinary gamma-glutamyl transferase (GGT) levels can be indicative of exercise-induced renal damage. In the literature, there exists numerous studies on exercise-induced proteinuria; but studies investigating the effects of exercise on urinary GGT levels are quite few. We aimed to evaluate the effects of exercise on renal function, expressed through the exercise-induced differences in urinary GGT, creatinine and protein levels.

METHODS

The study was performed on 12 female and 12 male volleyball players of the same sports club. Urine samples collected before and 1 h after the exercise were analyzed for urinary GGT, creatinine and protein amounts.

RESULTS

No statistically significant difference was observed between pre- and postexercise urinary GGT levels (U/L and U/g creatinine) of female and male volleyball players (P>0.05). A significant exercise-induced increase in urinary protein excretion was observed for the male players, while a significant exercise-induced increase in urinary creatinine excretion was observed for the female players (P<0.05). When urinary GGT levels (U/L) were compared separately for setters and spikers, it was observed that female players had no significant difference, while male spikers had a statistically significant exercise-induced increase in the urinary GGT levels (U/L) (P<0.05).

CONCLUSIONS

We suggest that the insignificance of the exercise-induced increases in the urinary parameters could be due to the relatively short-course of the exercise and the timing of postexercise urine collection. A comprehensive study performed on more subjects could yield results that are more significant.

Pancreatic islet function in omega-3 fatty acid-depleted rats: alteration of calcium fluxes and calcium-dependent insulin release

Considering the insufficient supply of long-chain polyunsaturated omega-3 fatty acids often prevailing in Western populations, this report deals mainly with alterations of Ca(2+) fluxes and Ca(2+)-dependent insulin secretory events in isolated pancreatic islets from omega-3-depleted rats. In terms of (45)Ca(2+) handling, the islets from omega-3-depleted rats, compared with those from normal animals, displayed an unaltered responsiveness to an increase in extracellular K(+) concentration, a lower inflow rate and lower fractional outflow rate of the divalent cation, and higher (45)Ca(2+)-labeled cellular pool(s) at isotopic equilibrium. The latter anomaly was corrected 120 min after intravenous injection of a novel medium-chain triglyceride-fish oil (MCT:FO) emulsion, distinct from a control omega-3-poor MCT-olive oil (MCT:OO) emulsion. At 8.3 mM D-glucose, insulin release was higher in islets from omega-3-depleted rats vs. control animals, coinciding with a higher cytosolic Ca(2+) concentration. The relative magnitude of the increase in insulin output attributable to a rise in D-glucose as well as extracellular Ca(2+) or K(+) concentration, to the absence vs. presence of verapamil and to the presence vs. absence of extracellular Ca(2+), theophylline, phorbol 12-myristate 13-acetate, or Ba(2+), was always more pronounced in islets from omega-3-depleted rats injected with the MCT:OO compared with the MCT:FO emulsion. A comparable situation prevailed when comparing islets from noninjected omega-3-depleted and normal rats. In light of these and previous findings, we propose that an impairment of Na(+),K(+)-ATPase activity plays a major, although not an exclusive, role in the perturbation of Ca(2+) fluxes and Ca(2+)-dependent secretory events in the islets from omega-3-depleted rats.

Antibiotic-associated diarrhea in a Turkish outpatient population: investigation of 288 cases

Oral antibiotics are often prescribed, especially for respiratory tract infections in the community. The widespread use of broad-spectrum antibiotics causes an increased incidence of antibiotic-associated diarrhea (AAD). Although AAD has been studied in hospitalized patients, there is little available information concerning the characteristics of AAD in outpatient populations. The aim of this study was to investigate the clinical and laboratory findings of adult patients with community-acquired AAD. Between June 1998 and December 2003, the clinical reports of 288 patients were retrospectively reviewed. We observed that the duration between the start of antibiotic treatment and onset of symptoms was 7 days in most of the patients (86%), and the mean time was 9+/-1.0 days. The diarrhea was self-limited in all cases and mean duration of symptoms was 3 (+/-1.0) days (1-7 days). The most common symptoms were abdominal discomfort and tenesmus (61.1%), while elevated WBC counts and fever were detected rarely. We were able to perform microbiologic investigations in only 88 patients because of the financial problems. Of the 88 stool specimens tested, none of them were positive for pathogenic bacterial growth or toxin A production.

Enzyme-to-enzyme channelling in the early steps of glycolysis in rat pancreatic islets

The metabolism of D-glucose displays anomeric specificity in rat pancreatic islets. The aim of the present report is to investigate whether such a situation implies enzyme-to-enzyme tunnelling of metabolites in the early steps of glycolysis. For such a purpose, the modelling of alpha- and beta-D-glucose catabolism, itself based on available information concerning both the utilisation of these two anomers and the intrinsic properties of phosphoglucoisomerase, was first examined. According to a theoretical model with enzyme-to-enzyme channelling, the generation of 3HOH from D-[2-3H]glucose should be higher in islets exposed to beta-D-glucose rather than alpha-D-glucose, whilst the opposite situation should prevail in the case of D-[5-3H]glucose conversion to 3HOH. Experimental data collected in rat islets incubated for 60 min at 4 degrees C in the presence of either alpha- or beta-D-glucose mixed with tracer amounts of either alpha- or beta-D-[2- 3H]glucose and alpha- or beta-D-[5-3H]glucose indicate that the beta/alpha ratio for D-[2-3H]glucose conversion to 3HOH is indeed higher than the beta/alpha ratio for D-[5-3H]glucose conversion to 3HOH. These findings are consistent with the postulated enzyme-to-enzyme tunnelling of glycolytic intermediates between hexokinase isoenzyme(s), phosphoglucoisomerase and, possibly, phosphofructokinase.

Changes in NAD/ADP-ribose metabolism in rectal cancer

The extent of ADP-ribosylation in rectal cancer was compared to that of the corresponding normal rectal tissue. Twenty rectal tissue fragments were collected during surgery from patients diagnosed as having rectal cancer on the basis of pathology results. The levels of ADP-ribosylation in rectum cancer tissue samples (95.9 +/- 22.1 nmol/ml) was significantly higher than in normal tissues (11.4 +/- 4 nmol/ml). The level of NAD+ glycohydrolase and ADP-ribosyl cyclase activities in rectal cancer and normal tissue samples were measured. Cancer tissues had significantly higher NAD+ glycohydrolase and ADP-ribosyl cyclase activities than the control tissues (43.3 +/- 9.1 vs 29.2 +/- 5.2 and 6.2 +/- 1.6 vs 1.6 +/- 0.4 nmol mg(-1) min(-1)). Approximately 75% of the NAD+ concentration was consumed as substrate in rectal cancer, with changes in NAD+/ADP-ribose metabolism being observed. When [14C]-ADP-ribosylated tissue samples were subjected to SDS-PAGE, autoradiographic analysis revealed that several proteins were ADP-ribosylated in rectum tissue. Notably, the radiolabeling of a 113-kDa protein was remarkably greater than that in control tissues. Poly(ADP)-ribosylation of the 113-kDa protein in rectum cancer tissues might be enhanced with its proliferative activity, and poly(ADP)-ribosylation of the same protein in rectum cancer patients might be an indicator of tumor diagnosis.

Labelling of lipids by D-[1-14C]glucose, D-[6-14C] glucose and D-[3-3H]glucose in pancreatic islets from normal and GK rats

In pancreatic islets prepared from either normal or GK rats and incubated at either low (2.8 mM) or high (16.7 mM) D-glucose concentration, the labelling of both lipids and their glycerol moiety is higher in the presence of D-[1-14C]glucose than D-[6-14C]glucose. The rise in D-glucose concentration augments the labelling of lipids, the paired 14C/3H ratio found in islets exposed to both D-[1-14C]glucose or D-[6-14C]glucose and D-[3-3H]glucose being even slightly higher at 16.7 mM D-glucose than that found, under otherwise identical conditions, at 2.8 mM D-glucose. Such a paired ratio exceeds unity in islets exposed to D-[1-14C]glucose. The labelling of islet lipids by D-[6-14C]glucose is about 30 times lower than the generation of acidic metabolites from the same tracer. These findings indicate (i) that the labelling of islet lipids accounts for only a minor fraction of D-glucose catabolism in pancreatic islets, (ii) a greater escape to L-glycerol-3-phosphate of glycerone-3-phosphate generated from the C1-C2-C3 moiety of D-glucose than D-glyceraldehyde-3-phosphate produced from the C4-C5-C6 moiety of the hexose, (iii) that only a limited amount of [3-3H]glycerone 3-phosphate generated from D-[3-3H]glucose is detritiated at the triose phosphate isomerase level before being converted to L-glycerol-3-phosphate, and (iv) that a rise in D-glucose concentration results in an increased labelling of islet lipids, this phenomenon being somewhat more pronounced in the case of D-[1-14C]glucose or D-[6-14C]glucose rather than D-[3-3H]glucose.

Metabolism of tritiated D-glucose anomers in rat erythrocytes

It was recently proposed that alpha-D-glucose 6-phosphate may undergo enzyme-to-enzyme channelling between glucokinase and phosphoglucoisomerase in rat pancreatic islets. The present study aims at exploring whether a different situation prevails in cells deprived of glucokinase, namely in erythrocytes. At anomeric equilibrium, the ratio between D-[2-3H]glucose and D-[5-3H]glucose conversion to 3HOH was lower in rat erythrocytes incubated for 60 min at 4 degrees C in the presence of 2.8 mM, rather than 8.3 mM, D-glucose. This coincided with both a greater relative increase in beta-D-[5-3H]glucose, as compared to alpha-D-[5-3H]glucose, conversion to 3HOH and an increase in the beta/alpha ratio for 3HOH generation from D-[5-3H]glucose in response to an increase in the anomeric concentration from 2.8 to 8.3 mM, the suppression of the difference between the beta/alpha ratios for 3HOH generation from D-[2-3H]glucose and D-[5-3H]glucose in the erythrocytes incubated at 8.3 mM, as distinct from 2.8 mM, alpha- and beta-D-glucose, and a [2-3H]/[5-3H] ratio for 3HOH generation lower than unity in erythrocytes exposed to alpha-D-glucose but not significantly different from unity in the presence of beta-D-glucose. These findings emphasize the relevance of alpha-D-glucose 6-phosphate channelling between hexokinase and phosphoglucoisomerase as a determinant of the difference between D-[2-3H]glucose and D-[5-3H]glucose conversion to 3HOH, and reveal that the regulation of such a tunnelling process by the concentration of the D-glucose represents, in rat erythrocytes, a mirror image of that observed in rat pancreatic islets. The regulation of this process thus tightly depends on the identity of the hexokinase enzyme mainly responsible for the phosphorylation of D-glucose in distinct cell types.

Metabolism of D-glucose anomers in rat pancreatic islets exposed to equilibrated D-glucose

This study aims at establishing the contribution of alpha- and beta-D-glucose to the total generation of (3)HOH by rat pancreatic islets exposed to D-[2 - (3)H]glucose or D-[5 - (3)H] glucose at anomeric equilibrium. The islets were incubated for 60 min at 4 degrees C in the presence of equilibrated D-glucose (2.8 and 8.3 mM) mixed with tracer amounts of either alpha- or beta-D-glucose labelled with tritium on either the C (2) or C (5) of the hexose. Relative to their respective concentrations, (3)HOH generation from the anomers labelled with tritium on the C (2) or C (5) of the hexose provided beta/alpha ratios comparable to those previously found at both 2.8 and 8.3 mM, when the islets were exposed to each anomer separately. The relative contributions of each anomer to the total generation of (3)HOH was also close to the theoretical values derived from mathematical models for the catabolism of D-glucose at anomeric equilibrium in rat islets at both 2.8 and 8.3 mM and in the case of both D-[2 - (3)H]glucose and D-[5 - (3)H]glucose. Thus, even in islets exposed to D-glucose at anomeric equilibrium, the metabolic fate of alpha-D-glucose differs vastly from that of beta-D-glucose, the enzyme-to-enzyme channelling between hexokinase isoenzymes, especially glucokinase, and phosphoglucoisomerase being restricted to alpha-D-glucose 6-phosphate.

Underestimation of D-glucose utilisation as judged from the conversion of D-[3-(3)H]glucose to (3)HOH

AIMS/HYPOTHESIS

The conversion of D-[3-(3)H]glucose to (3) HOH is currently measured to assess D-glucose utilisation. The validity of such a procedure was re-evaluated.

METHODS

The conversion of D-[3-(3)H]glucose and D-[5-(3)H]glucose to (3) HOH was measured in rat pancreatic islets, parotid cells and erythrocytes. The tritiation of lipids were also examined in islets exposed to D-[3-(3)H]glucose or D-[5-(3)H]glucose.

RESULTS

In rat pancreatic islets and parotid cells, but not in rat erythrocytes, the generation of (3) HOH from D-[3-(3)H]glucose underestimates the rate of D-glucose utilisation, this being apparently attributable to a partial escape from detritiation of [1-(3)H]glycerone-3-phosphate. Such an escape phenomenon resulted in a higher tritiation of lipids in pancreatic islets exposed to D-[3-(3)H]glucose, rather than D-[5-(3)H]glucose. Its relative extent was affected by a number of environmental factors such as the cell type under consideration, the metabolic status of the animals, and the extracellular concentration of D-glucose.

CONCLUSION/INTERPRETATION

These findings impose a reservation on the use of D-[3-(3)H]glucose conversion to (3)HOH as a tool to assess the utilisation of the hexose in some cell types.

Renal hemodynamic effects of L-NAME during postnatal maturation in conscious lambs

The purpose of the present study was to investigate the effects of the L-arginine analogue, NG-nitro-L-arginine methyl ester, L-NAME, in modulating renal hemodynamics during postnatal maturation in conscious chronically instrumented lambs. To this end, renal hemodynamic responses to intravenous injection of 10, 20, and 40 mg/kg L-NAME, as well as its inactive enantiomer D-NAME, were measured for 4 h in conscious lambs approximately 1 week (n=10), 3 weeks (n=12), and 6 weeks (n=14) of age. Administration of L-NAME was associated with an increase in renal vascular resistance (RVR) leading to a decrease in renal blood flow. One-week-old lambs were more sensitive to the effects of L-NAME, a marked increase in RVR occurring after the smallest dose administered at 1 week but not at 3 and 6 weeks of age. Renal hemodynamic effects of L-NAME as well as the duration of the responses were also age dependent, such that changes in RVR were greatest and most prolonged in 1-week-old lambs. In addition, a smaller dose of L-NAME was required to attenuate acetylcholine-induced renal vasodilation in lambs aged 1 week compared with older animals. Our data provide new evidence to support the premise that endogenously produced nitric oxide plays a predominant role in regulating renal vascular tone early in life.

Enzymic activities in two populations of purified rat islet beta-cells

In terms of glucose sensing by pancreatic islet beta-cells, emphasis is currently placed on both the role of glucokinase, with negligible activity of low-Km hexokinase(s), and the prevalence of the oxidative over non-oxidative modality of glycolysis, a situation tentatively attributed, in part at least, to a low activity of lactate dehydrogenase. Conflicting information is available, however, on the activity of both low-Km hexokinase(s) and lactate dehydrogenase in purified beta-cell homogenates. This issue was reinvestigated, therefore, in two populations of purified rat islet beta-cells selected on the basis of their low (betaL) or high (betaH) content in reduced pyridine nucleotides. The size and protein content of betaH cells represented about twice that of betaL cells. Such was also the case for low-Km hexokinase(s), lactate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, glutamate dehydrogenase and glutamate-alanine and glutamate-aspartate transaminases. Whether in betaH or betaL cells, the activity of low-Km hexokinase(s) was at least as high as or higher than that of glucokinase. In both betaH and betaL, the activity of lactate dehydrogenase exceeded that required to catalyze the full reduction of glucose-derived pyruvate to L-lactate, as estimated from the rate of D-glucose phosphorylation under physiological conditions. These findings thus argue against a low expression of either low-Km hexokinase(s) or lactate dehydrogenase as major determinants of the glucose-sensing device in beta-cells.

Assessment by D-[(3)H]mannoheptulose uptake of B-cell density in isolated pancreatic islets from Goto-Kakizaki rats

The uptake of D-[3H]mannoheptulose by isolated pancreatic islets was recently proposed as a tool to assess the relative contribution of insulin-producing cells to the total mass of the islets. In the present study, the uptake of the tritiated heptose over 60 min incubation at 37 degrees C was about 21% lower in islets from hereditarily diabetic rats (GK rats) than in islets from control animals, this decrease being virtually identical to that documented previously by morphometric analysis of islets from the same type of rats. The intracellular 3HOH space and extracellular [U-14C]sucrose space were not significantly different in control and diabetic rats, at least when the comparison was restricted to animals of the same sex. There was a trend, however, towards a somewhat lower D-[5-3H]-glucose intracellular distribution space in islets from GK rats, as compared to control animals. These findings provide further support to the validity of D-[3H]mannoheptulose uptake as a tool to assess the density of insulin-producing cells in isolated islets.

Uptake of D-mannoheptulose by normal and tumoral pancreatic islet cells

D-mannoheptulose was recently proposed as a possible tool to label preferentially insulin-producing cells in the pancreatic gland. In the present study, D-[3H]-mannoheptulose uptake by rat pancreatic islets or dispersed islet cells was found to represent a time-related and temperature-sensitive process inhibited by cytochalasin B. This mould metabolite also inhibited the efflux of D-[3H]-mannoheptulose from prelabelled islets. After 60 min incubation at 37 degrees C, the apparent intracellular distribution space of the tritiated heptose was close to or somewhat higher than that of D-[5-3H]glucose and close to 50% of the intracellular 3HOH space. It was further enhanced by D-glucose and a high concentration of 10 mM of D-mannoheptulose. The uptake of D-[3H]mannoheptulose was much lower however than that of D-[3H]mannoheptulose hexaacetate. As judged from the fate of D-mannoheptulose hexa[2-14C]acetate, the latter ester was efficiently hydrolyzed in the islet cells. The internalization of D-[3H]mannoheptulose (or its ester) coincided with the generation of tritiated acidic metabolites, reflecting phosphorylation of the heptose. The situation found in normal islet cells sharply differed from that found in tumoral islet cells of either the RINm5F or INS-1 line, in which the apparent distribution space of D-[3H]mannoheptulose represented only about 3 and 9%, respectively, of the intracellular 3HOH space. These results indicate that the entry of D-mannoheptulose into islet cells represents a carrier-mediated process, possibly mediated at the intervention of GLUT2 and, hence, provide further support to the possible use of a suitable D-mannoheptulose analog as a tool for the preferential labelling of insulin-producing cells in the pancreatic gland.

Uptake of D-mannoheptulose by rat erythrocytes, hepatocytes and parotid cells

D-[3H]mannoheptulose (or D-[1-14C] mannoheptulose) net uptake was measured in rat erythrocytes, parotid cells and hepatocytes. In the erythrocytes and parotid cells, the intracellular distribution space of the heptose (0.1 mM) represented only about 1 and 13%, respectively, of the intracellular 3HOH space. In hepatocytes, however, it amounted to approximately 45% of the intracellular 3HOH space. In all cases, the apparent distribution space of D-[3H]mannoheptulose hexaacetate largely exceeded that of unesterified D-[3H]mannoheptulose. Relative to the intracellular water space, the generation of acidic metabolites (expressed as an apparent distribution space) from radioactive D-mannoheptulose was one order of magnitude lower in parotid cells (< or = 3%) than in hepatocytes (> or = 20%). These findings are compatible with the hypothesis that D-mannoheptulose is transported into cells mainly, if not exclusively, at the intervention of GLUT2.

Nitric oxide modulates arterial baroreflex control of heart rate in conscious lambs in an age-dependent manner

Experiments were carried out in conscious chronically instrumented lambs aged 1 (n = 6) and 6 wk (n = 5) to evaluate the arterial baroreflex control of heart rate (HR) during postnatal maturation and to investigate any modulatory role of endogenously produced nitric oxide (NO). Before and after intravenous administration of 20 mg/kg of the L-arginine analog N(G)-nitro-L-arginine methyl ester (L-NAME), the arterial baroreflex was assessed by measuring HR responses to increases and decreases in systolic arterial pressure achieved by intravenous administration of phenylephrine and sodium nitroprusside. The HR range over which the baroreflex operates and minimum HR as well as maximum gain were greater at 1 than at 6 wk of age. These age differences were abolished in the presence of L-NAME, which decreased the HR range and gain of the arterial baroreflex control of HR at 1 but not at 6 wk of age. These data provide new information that age-dependent effects of the arterial baroreflex appear to result from effects of endogenously produced NO.

Uptake of 1-deoxy-1-[125I]iodo-D-mannoheptulose by different cell types: in vitro and in vivo experiments

D-mannoheptulose was recently proposed as a tool to label preferentially insulin-producing cells in the pancreatic gland in the perspective of the non-invasive imaging of the endocrine pancreas. In such a perspective, we have now synthesized 1-deoxy-1-[125I]iodo-D-mannoheptulose ([125I]MH) and examined its uptake by different rat cell types. No phosphorylation of [125I]MH by bovine heart hexokinase could be detected. The apparent distribution space of [125I]MH largely exceeded that of [U-14C]sucrose, considered as an extracellular marker, in erythrocytes, parotid cells, hepatocytes, pancreatic pieces and isolated pancreatic islets. Relative to the mean intracellular distribution space of 3HOH, that of [125I]MH was not significantly different in pancreatic pieces from either normal rats or streptozotocin-induced diabetic animals (STZ rats). In pancreatic islets, the uptake of [125I]MH was decreased at low temperature, but failed to be significantly affected by cytochalasin B. Sixty min after the intravenous injection of [125I]MH, the radioactive content of selected organs displayed the following hierarchy: muscle<pancreas<liver<parotid<kidney<plasma. In this respect, there was no obvious difference between control and STZ rats. Taken as a whole, these findings suggest that 1-deoxy-1-[125I]iodo-D-mannoheptulose does not display the same specificity towards GLUT2, as that previously documented in the case of D-[3H]- mannoheptulose.

D-mannoheptulose phosphorylation by hexokinase isoenzymes

D-mannoheptulose is a specific inhibitor of D-glucose phosphorylation by hexokinase isoenzymes. In the present study, the phosphorylation of this heptose was investigated by either a spectrophotometric or radioisotopic procedure. Using yeast hexokinase, the phosphorylation of 25 mM D-mannoheptulose only represented 0.02% of that of 5 mM D-glucose. Such a percentage was increased to 3.93% in the case of bovine heart hexokinase. In the latter case, the Km for D-mannoheptulose was close to 0.2 mM and both D-glucose (0.1-1.0 mM) and D-glucose 6-phosphate (also 0.1-1.0 mM) inhibited the phosphorylation of the heptose (0.03-0.60 mM). Human B-cell glucokinase also catalyzed the phosphorylation of D-mannoheptulose (0.1 mM), which was now increased in a bell-shaped manner by D-glucose (1.0-20 mM). Likewise, rat parotid gland, liver and pancreatic islet homogenates catalyzed the phosphorylation of D-[3H]mannoheptulose. The results obtained in these three tissues differed from one another by their absolute values (per mg wet wt.), relative values (by reference to the phosphorylation rate of 10 mM D-glucose), and sensitivity to inhibition by D-glucose (10 mM).

D-mannoheptulose uptake and its metabolic and secretory effects in human pancreatic islets

D-mannoheptulose was recently proposed to be transported into cells at the intervention of GLUT2. Since GLUT1, rather than GLUT2, represents the major carrier system for the transport of monosaccharides across the islet B-cell plasma membrane in human subjects, the uptake of D-mannoheptulose and its metabolic and secretory effects were investigated in human islets. The uptake of D-glucose reached much more rapidly a close-to-equilibrium value in isolated islets than in pieces of pancreas obtained from the same donor. The distribution space of D-[3H]mannoheptulose in the human islets largely exceeded that of [U-14C]sucrose, considered as an extracellular marker, and did not differ significantly from that of 3HOH. In the human islets, the heptose (10.0 mM) inhibited both D-[5-3H]glucose utilization and D-[U-14C] glucose oxidation, and decreased glucose-stimulated insulin release to the same extent as D-mannoheptulose hexaacetate. These findings indicate that a suitable radioactive analog of D-mannoheptulose could be used, in human like in rat islets, for preferential labelling of the endocrine moiety of the pancreatic gland.