Charge Transfer-Promoted Excited State of a Heavy-Atom-Free Photosensitizer for Efficient Application of Mitochondria-Targeted Fluorescence Imaging and Hypoxia Photodynamic Therapy

Conventional photosensitizers (PSs) used in photodynamic therapy (PDT) have shown preliminary success; however, they are often associated with several limitations including potential dark toxicity in healthy tissues, limited efficacy under acidic and hypoxic conditions, suboptimal fluorescence imaging capabilities, and nonspecific targeting during treatment. In response to these challenges, we developed a heavy-atom-free PS, denoted as Cz-SB, by incorporating ethyl carbazole into a thiophene-fused BODIPY core. A comprehensive investigation into the photophysical properties of Cz-SB was conducted through a synergistic approach involving experimental and computational investigations. The enhancement of intersystem crossing (kISC) and fluorescence emission (kfl) rate constants was achieved through a donor-acceptor pair-mediated charge transfer mechanism. Consequently, Cz-SB demonstrated remarkable efficiency in generating reactive oxygen species (ROS) under acidic and low-oxygen conditions, making it particularly effective for hypoxic cancer PDT. Furthermore, Cz-SB exhibited good biocompatibility, fluorescence imaging capabilities, and a high degree of localization within the mitochondria of living cells. We posit that Cz-SB holds substantial prospects as a versatile PS with innovative molecular design, representing a potential "one-for-all" solution in the realm of cancer phototheranostics.

Dual anticancer and antibacterial activity of fluorescent naphthoimidazolium salts

Cancer has emerged as a significant global health challenge, ranking as the second leading cause of death worldwide. Moreover, cancer patients frequently experience compromised immune systems, rendering them susceptible to bacterial infections. Combining anticancer and antibacterial properties in a single drug could lead to improved overall treatment outcomes and patient well-being. In this context, the present study focused on a series of hydrophilic naphthoimidazolium salts with donor groups (NI-R), aiming to create dual-functional agents with antibacterial and anticancer activities. Among these compounds, NI-TPA demonstrated notable antibacterial activity, particularly against drug-resistant bacteria, with MIC value of 7.8 μg mL-1. Furthermore, NI-TPA exhibited the most potent cytotoxicity against four different cancer cell lines, with an IC50 range of 0.67-2.01 μg mL-1. The observed high cytotoxicity of NI-TPA agreed with molecular docking and dynamic simulation studies targeting c-Met kinase protein. Additionally, NI-TPA stood out as the most promising candidate for two-photo excitation, fluorescence bioimaging, and localization in lysosomes. The study findings open new avenues for the design and development of imidazolium salts that could be employed in phototheranostic applications for cancer treatment and bacterial infections.

Imidazolium-Based Heavy-Atom-Free Photosensitizer for Nucleus-Targeted Fluorescence Bioimaging and Photodynamic Therapy

The development of heavy-atom-free photosensitizers (PSs) for photodynamic therapy (PDT) has encountered significant challenges in achieving simultaneous high fluorescence emission and reactive oxygen species (ROS) generation. Moreover, the limited water solubility of these PSs imposes further limitations on their biomedical applications. To overcome these obstacles, this study presents a molecular design strategy employing hydrophilic heavy-atom-free PSs based on imidazolium salts. The photophysical properties of these PSs were comprehensively investigated through a combination of experimental and theoretical analyses. Notably, among the synthesized PSs, the ethylcarbazole-naphthoimidazolium (NI-Cz) conjugate exhibited efficient fluorescence emission (ΦF = 0.22) and generation of singlet oxygen (ΦΔ = 0.49), even in highly aqueous environments. The performance of NI-Cz was validated through its application in fluorescence bioimaging and PDT treatment in HeLa cells. Furthermore, NI-Cz holds promise for two-photon excitation and type I ROS generation, nucleus localization, and selective activity against Gram-positive bacteria, thereby expanding its scope for the design of heavy-atom-free PSs and phototheranostic applications.

Photovoltaic Effects of Dye-Sensitized Solar Cells Using Double-Layered TiO2 Photoelectrodes and Pyrazine-Based Photosensitizers

In this study, to obtain high performances of the dye-sensitized solar cells using the optimal TiO₂ photoelectrode for the synthesized pyrazine-based organic photosensitizers, three types of TiO₂ photoelectrodes were fabricated and evaluated for comparison. The double-layered nanoporous TiO₂ photoelectrode (SPD type) consisted of a dispersed TiO₂ layer and a transparent TiO₂ layer. The single-layered nanoporous TiO₂ photoelectrodes (D type and SP type) consisted of a dispersed TiO₂ layer and a transparent TiO₂ layer, respectively. The surface area, pore volume, and crystalline structures of the three types of TiO₂ photoelectrodes were analyzed by Brunauer-Emmett-Teller method, field-emission scanning electron microscopy, and X-ray diffractometry to confirm their crystallinity and surface morphology. The structures of the three types of TiO₂ photoelectrode-adsorbed organic sensitizers were investigated using X-ray photoelectron spectroscopy. The photovoltaic performances of DSSC devices using three organic photosensitizers adsorbed onto the three types of TiO₂ photoelectrodes were investigated under a light intensity of 100 mW/cm² at AM 1.5. The DSSC device using double-layered SPD type TiO₂ photoelectrodes displayed 1.31∼2.64% efficiency, compared to single-layered SP type TiO₂ photoelectrodes (1.31∼2.50%) and D type TiO₂ photoelectrodes (0.90∼1.54%), using organic photosensitizers. The DSSC device using the SPD type TiO₂ photoelectrode and trifluoromethylbenzopyrazine (TPPF) as a photosensitizer showed the highest performances: J _sc of 5.69 mA/cm², V _oc of 0.69 V, FF of 0.67, and efficiency of 2.64%. The relationship between photovoltaic effects and interfacial resistance characteristics of DSSCs using the three organic photosensitizers adsorbed onto the three types of TiO₂ photoelectrodes could be interpreted from interfacial resistances according to frequency through impedance analysis.

Imidazole-carbazole conjugate for two-photon-excited photodynamic therapy and fluorescence bioimaging

A heavy-atom-free Photosensitizer (CI) based on an imidazole-carbazole conjugate exhibited strong fluorescence emission and ROS generation via both type I and II mechanisms. In particular, CI showed efficient photodynamic therapy...

Photovoltaic Performances of Dye-Sensitized Solar Cells Based on Modified Polybutadiene Matrix Electrolytes by Sol-Gel Process

A new type of polymer matrix electrolyte based on modified polybutadiene (modified PB) was developed for dye-sensitized solar cells (DSSCs) to improve their stability. The modified PB was fabricated by cross-linking the reaction of polybutadiene with siloxane groups as a substitute sol-gel process. A DSSC device using the modified PB matrix electrolyte showed an open-circuit voltage of 0.64 V, a short-circuit current density of 15.00 mA/cm², and a fill factor of 0.58 under photointensity of 100 mW/cm² at AM 1.5, consequently leading to an overall solar energy conversion efficiency of 5.49%. The DSSC device using the modified PB matrix electrolyte improved the conductivity, and the charge transfer ability showed the outstanding stability of the device.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

Hypochlorite-Activated Fluorescence Emission and Antibacterial Activities of Imidazole Derivatives for Biological Applications

The ability to detect hypochlorite (HOCl/ClO-) in vivo is of great importance to identify and visualize infection. Here, we report the use of imidazoline-2-thione (R 1 SR 2 ) probes, which act to both sense ClO- and kill bacteria. The N2C=S moieties can recognize ClO- among various typical reactive oxygen species (ROS) and turn into imidazolium moieties (R 1 IR 2 ) via desulfurization. This was observed through UV-vis absorption and fluorescence emission spectroscopy, with a high fluorescence emission quantum yield (ՓF = 43-99%) and large Stokes shift (∆v∼115 nm). Furthermore, the DIM probe, which was prepared by treating the DSM probe with ClO-, also displayed antibacterial efficacy toward not only Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) but also methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-EC), that is, antibiotic-resistant bacteria. These results suggest that the DSM probe has great potential to carry out the dual roles of a fluorogenic probe and killer of bacteria.

Molecular Design toward Heavy-Atom-free Photosensitizers Based on the C═S Bond and their Dual Functions in Hypoxia Photodynamic Cancer Therapy and ClO- Detection

In this article, we designed and synthesized the thionated NpImidazole derivatives BS and NS, new heavy-atom-free photosensitizers, which efficiently generate a triplet excited state with high singlet oxygen quantum yield. The introduction of the C═S bond to the NpImidazole core is essential for increasing spin-orbit coupling (SOC). The fluorescence emission of BS and NS was quenched at standard ambient temperature, accompanied with the increase in the ISC process from the singlet states to triplet excited states via thionation. BS and NS showed negligible dark cytotoxicity against HeLa cells in working concentration. In contrast, BS and NS rapidly induced cell death under blue light irradiation both under normoxia and hypoxia conditions. Our current study demonstrates that the C═S group can play an important role in type I ROS generation of PSs, which are unprecedented in the previous reports. Finally, the photophysical changes were assigned to the oxidative desulfurization of the C═S group of BS and NS to the C═O group of the corresponding BO and NO via hypochlorite. The combined results demonstrated the dual function of BS and NS as a fluorescent imaging agent for ClO^- and an anti-cancer therapeutic by PDT that showed the potential strategy for "one-for-all" and multifunctional agents.

A molecular design towards sulfonyl aza-BODIPY based NIR fluorescent and colorimetric probe for selective cysteine detection

A new fluorescent and colorimetric probe based-on sulfonyl aza-BODIPY (BDP-1–3) are designed and synthesized for selective cysteine detection.

Visual Simultaneous Detection and Real-Time Monitoring of Cadmium Ions Based on Conjugated Polydiacetylenes

We prepared the monomer PCDA-HP composed of 5-hydroxy-N ¹,N ³-bis(pyridin-2-ylmethyl)isophthalamide (HP) as a cadmium ion tweezer and then polymerized them to form a polydiacetylene (PDA)-based sensor (PDA-HP), which displayed selective and sensitive colorimetric and fluorometric change upon addition of a cadmium ion (Cd²⁺) at both pH 7.4 and 6.8. The PDA-HP polymer was highly selective for Cd²⁺ over other metal ions with colorimetric change. In addition, the PDA-HP chemosensor also showed a red fluorescence change in the presence of Cd²⁺ at both pH 7.4 and 6.8. Naked-eye detection of Cd²⁺ was accomplished in an aqueous solution through a PDA-based sensor system. Finally, the lowest energy structure of an HP chelator was obtained by the crystal structure and density functional theory (DFT) calculations.

Continuous glucose monitoring in patients with type 2 diabetes: Why? When? Whom?

The overall assessment of glycaemic control in patients with type 2 diabetes should normally include the monitoring of three parameters that are usually depicted as the 'glucose triad': HbA(1c), fasting plasma glucose (FPG) and postprandial glucose (PPG) excursions. However one additional marker, the so-called 'glucose variability' might be as important as the three others since it has been demonstrated that both upward and downward glucose fluctuations are potent activators of oxidative stress. Even though many methods have been proposed for assessing glucose fluctuations, the 'mean amplitude glucose excursions' (MAGE) index remains the 'gold standard'. However MAGE estimation requires the use of continuous glucose sensors. Despite the debate on the reliability and cost of the devices that permit glucose monitoring, we suggest that interventional trials designed to evaluate the effects of glucose fluctuations on diabetic complications should benefit from the use of continuous glucose monitoring systems (CGMSs). More prosaically, the use of these technologies could be extended to current clinical care of type 2 diabetic patients especially for motivating them to accept earlier insulin treatments in case of 'oral antidiabetic drug secondary failure', and further for choosing the most appropriate insulin regimen.

Dichotomous responses of inter and postprandial hyperglycaemia to short-term calorie restriction in patients with type 2 diabetes

BACKGROUND

In type 2 diabetes the effects of short-term calorie restrictions on glycaemia are usually judged on fasting plasma glucose. As fasting duration rarely exceeds 2-3 h, we determined the effects of calorie restriction over different daytime periods using a continuous glucose monitoring system (CGMS) in noninsulin-using patients with type 2 diabetes.

DESIGN

Fourteen poorly controlled (mean HbA1c = 9.3%) overweight or obese patients (mean body mass index = 30.1 +/- 0.7 kg m(-2)) with type 2 diabetes were investigated twice with a CGMS, at baseline and at the end of a 18-day calorie-restricted diet (1490 kcal day(-1)). Areas under curves (AUCs) of 24-h glucose monitoring were measured and divided into postprandial and interprandial AUCs according to meal times.

RESULTS

Areas under curves of 24-h glucose monitoring were significantly decreased after dieting: -37%, P = 0.0047. Both post and interprandial AUCs were significantly diminished (-26%, P = 0.0186 and -48%, P = 0.0037, respectively), but changes in interprandial AUCs were more marked than changes in postprandial AUCs (P = 0.0060). Nycthemeral peaks of glucose were observed at mid-morning times and were not significantly different before (242 +/- 15 mg dL(-1)) and after dieting (227 +/- 16 mg dL(-1)).

CONCLUSIONS

Short-term calorie restriction in overweight or obese patients with type 2 diabetes resulted in dichotomous responses between interprandial and postprandial glycaemic excursions. The resistance of mid-morning glucose peaking to calorie restriction should result in additional dietary or pharmacological measures at breakfast.

[Dietary assessment in current clinical practice: how to conciliate rapidity, simplicity and reliability?]

Dietary interviews and food diaries are traditionally used for nutritional assessments. In clinical practice, these methods are time consuming, require high training, and thus remain poorly used. Furthermore, the results are frequently impaired by the underreporting phenomenon which can be due either to underrecording (failure to record what is eaten) or to undereating (volontary food restriction during the assessment period). These difficulties can be overcome by using rapid questionnaires based on 2 principles: 1) underreporting is less for proteins than for other macronutrients; 2) in developed countries, calories from proteins are relatively stable and contribute approximately to one sixth of the total daily energy intake. Estimations given by the rapid questionnaire lead to less misleading results than those provided by 7 day-food records. On the other hand, the rapid questionnaire gives an estimate of specific dietary behaviors such as nibbling, festive meals and consumption of salted entrées, sweet desserts and caloric beverages. In conclusion, helpful and simple recommendations for correcting main nutritional errors can be drawn from estimation of the above mentioned specific behaviors that correspond to a daily average of 500 kcalories.

Norepinephrine and posttraining memory consolidation in neonatal rats

Wistar rat pups, aged Postnatal Day 5, were trained in an olfactory associative learning task with citral odor as the conditioned stimulus (CS) and intraoral infusions of milk as the unconditioned stimulus (US). Following a 30-min training session, pups were injected with either the norepinephrine beta-receptor antagonist propranolol or the beta-receptor agonist isoproterenol. Pups were tested 24 hr later for an acquired relative odor preference for the CS. Propranolol injected immediately following training impaired memory for the CS in a dose-dependent manner. This posttraining effect lasted less than 4 hr. Isoproterenol injected immediately after training also impaired memory performance, even at very low doses. These results suggest that posttraining levels of norepinephrine play a critical role in memory consolidation in the newborn, with elevations or decrements in noradrenergic activity resulting in impaired memory.

Norepinephrine and posttraining memory consolidation in neonatal rats

Wistar rat pups, aged Postnatal Day 5, were trained in an olfactory associative learning task with citral odor as the conditioned stimulus (CS) and intraoral infusions of milk as the unconditioned stimulus (US). Following a 30-min training session, pups were injected with either the norepinephrine beta-receptor antagonist propranolol or the beta-receptor agonist isoproterenol. Pups were tested 24 hr later for an acquired relative odor preference for the CS. Propranolol injected immediately following training impaired memory for the CS in a dose-dependent manner. This posttraining effect lasted less than 4 hr. Isoproterenol injected immediately after training also impaired memory performance, even at very low doses. These results suggest that posttraining levels of norepinephrine play a critical role in memory consolidation in the newborn, with elevations or decrements in noradrenergic activity resulting in impaired memory.

Purification and characterization of the trypsin inhibitor from Cucurbita pepo var. patissonina fruits

Three trypsin inhibitor fractions were found in white bush fruits (Cucurbita pepo L. var. patissonina). One of them, CPPTI-fIII, was purified to homogeneity by means of affinity and ion exchange chromatography. It is a cysteine-poor protein with an approximate Mr of 21 000. The inhibitor contains arginine at position P1 of the reactive site and inhibits bovine trypsin, hog pancreatic kallikrein and subtilisin. This inhibitor differs from the inhibitors of white bush dormant seeds, CPPTI-I and CPPTI-II, in its amino-acid composition, molecular mass, amino-acid residue at position P1 of the reactive site and inhibition spectrum.

Comparative analysis of soluble porcine and human insulin (Novo) using the artificial pancreas

The porcine-extracted monocomponent insulins and human insulin (Novo) obtained by enzymatic conversion of porcine insulin had similar effects on glycemia balance when compared by means of an artificial pancreas during two 48-h studies 2 or 3 days apart. There was no significant difference between the maximum and minimum blood glucose circadian variations, the glycemic drops, and the Schlichtkrull coefficient. The speed of increase and decrease of glycemia during meals was slightly slower with human insulins than with porcine insulins, but the difference was not significant. Although comparable, the insulin requirements (per gram of ingested carbohydrate) were proportionately greater in the morning than during the rest of the day; the baseline requirements were also similar, but showed a trend toward increase during the day with both insulins.

[Comparative study of porcine and human regular insulins using an artificial pancreas]

Porcine extracted monocomponent insulins and human semi-synthetic insulins obtained by enzymatic conversion of porcine insulin had exactly the same clinical effectiveness on blood glucose balance when compared with an artificial pancreas during two 48-hour studies 2 or 3 days apart. There was no significant difference between maximum and minimum blood glucose variations, glycaemic falls and Schlichtkrull coefficient. Glycaemia increased and decreased during meals at a slightly slower rate with human insulin than with porcine insulin, but the differences were not significant. With both types of insulin therapy, insulin requirements per gram of ingested carbohydrates were proportionally more important in the morning than during the rest of the day, dans baseline requirements tended to increase during the day.

[Post-hyperglycaemic hypoglycaemia: effects of somatostatin (author's transl)]

Precise recordings of reactive (post-hyperglycaemic) hypoglycaemia were ensured by continuous blood glucose monitoring during oral glucose tolerance tests. The definition of hypoglycaemia was limited to the following criteria: absence of chemical diabetes; fall in blood sugar to less than 30% of the fasting level or to less than 2.50 mmol/l (0.45 g/l); development of clinical signs of hypoglycaemia. An infusion of somatostatin over 4 hours slowed down the initial rise in blood sugar during the first 90 minutes and the rise was prolonged throughout the infusion whatever its duration. The maximum glycaemia reached was 13.3 mmol/l (2.40 g/l) at the 250th minute. Interruption of the infusion led to a rapid fall in blood sugar to a level identical (2.1 and 2.5 mmol/l) with and without somatostatin respectively. Somatostatin infusions, while frankly diabetogenic in certain circumstances, do not prevent reactive hypoglycaemia but rather delay its onset.

Glucagon immunoreactivity and antidiabetic action of somatostatin in the totally duodeno-pancreatectomized and gastrectomized human

Ten patients who had been totally duodeno-pancreatectomized and totally (N = 1) or partially gastrectomized (N = 9) for chronic pancreatitis (N = 9) or pancreatic carcinoma (N = 1) were investigated. None had a measurable basal level of either plasma C-peptide or a C-peptide response to i.v. glucagon. Immunoreactive glucagon (IRG) was present in all patients, and the mean level (69 +/- 8 pg/ml) was not significantly different from the mean observed in normal subjects (81 +/- 16 pg/ml). Plasma IRG was unequivocally stimulated by arginine in 2 of the 10 subjects. The effect of somatostatin on plasma glucose and IRG during an oral glucose tolerance test was studied in 5 of the 10 patients. The effects of somatostatin on spontaneous hyperglycemia, plasma growth hormone, and IRG after withdrawal of insulin treatment was studied in 4 patients. Somatostatin blunted both the hyperglycemic and paradoxical IRG responses to the glucose challenge, and reduced the spontaneous rise of blood glucose that occurred after insulin withdrawal. This latter effect was not related to clear-cut changes in plasma growth hormone or in IRG. These data confirm the existence of circulating IRG in pancreatectomized patients and demonstrate the presence of circulating IRG in a completely gastrectomized and pancreatectomized patient. The somatostatin-induced improvement in glucose tolerance in the oral glucose tolerance test seems to be related to a reduction of the paradoxical IRG response. In contrast, the inhibition by somatostatin of the rise in blood glucose which occurs after insulin withdrawal does not seem to be mediated through IRG or growth hormone.

Effects of somatostatin added to insulin in a glucose-controlled insulin infusion system

Five insulin treated diabetics were studied on three consecutive days. Overnight variable intravenous insulin infusions were used before each study to maintain normoglycaemia and to calculate the optimal basal insulin infusion rate (1.1 +/- 0.1 U/h) which ws then kept constant throughout the study day. A standard 400 kCal breakfast with 25 g xylose was given at 0800 h. When the blood glucose rose above 4.1 mmol/l, an external artificial pancreas was used to infuse either extra insulin (day INS) or somatostatin for either 3h (day som) or the entire 8h experimental period (day SOM). Peak post-prandial blood glucose values were similar on all three days. The blood glucose rebounded after the cessation of the somatostatin infusion on day som. Post-prandial blood xylose peaks were lowered by somatostatin on both days but rebounded after the cessation of the somatostatin infusion on day som. The area under the plasma and urinary xylose curves was lowered by somatostatin only on day SOM. Growth hormone and glucagon levels were not statistically different on all 3 days. Thus somatostatin, when added to an optimal insulin infusion, minimised the insulin requirements by slowing intestinal absorption, but led to rebound hyperglycaemia if not feed-back controlled.

[Effects of somatostatin in oesophagal bleeding (author's transl)]

We used intravenous synthetic somatostatin to stem severe bleeding from oesophagites and oesophageal ulcer associated with renal failure hyponatremia and mental confusion. The ability of somatostatin to reduce splanchnic blood flow and portal pressure and to inhibit both gastrin release and the pentagastrin-stimulated secretion of gastric acid and pepsin provides its therapeutic use in multiple alimentary bleeding. When patients is considered poor candidate for surgery, somatostatin may prove a particularly valuable alternative to conventional medical treatments. We observed no side effects, with somatostatin, during a 72 h period of treatment. Since cimetidine give rise to mental confusion in ureamia or hyponatremia, somatostatin should be looked upon with particular interest in cases of gastro-intestinal bleeding associated with renal insufficiency.

[Late hypoglycaemia in chemical diabetes. Abnormalities of pancreatic glucagon secretion and effect of pectine (author's transl)]

Nineteen patients suffering from chemical diabetes either with (group A, ten cases) or without (group B, nine cases) reactive hypoglycaemia were included in the study and compared with seven control (group C). The following variables were measured over a 5 hour period during a standard oral glucose tolerance test (OGTT): (i) blood glucose by continuous monitoring; (ii) plasma insulin and glucagon levels by radioimmunoassay. Furthermore, in five diabetics of group A, the data from the standard OGTT were compared with those from a pectin-supplemented OGTT (9 g per square meter of body surface). Although the insulin response was similar glucagon levels were significantly higher (45.1 +/- 11.8 pmol/l) (p less than 0.01) in group B than in group A (9.6 +/- 1.3) and C (8.1 +/- 1.4 at 30 minutes). The high glucagon levels noted in group B may explain the absence of reactive hypoglycaemia. The pectin supplementation improved the OGTT pattern by blunting the blood glucose peak (p less than 0.05), and avoiding the reactive hypoglycaemia (p less than 0.01). The addition of pectin did not produce any significant effect on the insulin response while a significant increase in glucagon concentrations (p less than 0.05) was observed beyond the 150th minute. Therefore, the data suggest that pectin may improve the OGTT pattern by increasing the glucagon response in the late period of the test. The development of postprandial reactive hypoglycaemia seldom coincides with a plasma glucagon peak, while the absence of reactive hypoglycaemia tends to be associated with high levels of glucagon, as is the case in overt diabetes mellitus.

[Remission of diabetes during conventional insulin therapy or therapy controlled by use of an artificial pancreas]

12 recent acute-onset ketotic juvenile diabetics were optimally treated during 5 +/- days by means of an external artificial pancreas. Remission of diabetes occurred in 9 patients (75%). In a comparative group of 28 patients treated by conventional subcutaneous insulin, only 3 (11%) steady remissions were obtained. In a third group of 6 patients treated by insulin infusion without feed-back control, only 1 remission (17%) was obtained. The difference between these two groups and the first group (patients treated by the artificial pancreas) is significant (p less than 0.01). Urinary C-peptide/blood glucose ratio showed a steady improvement of insulin secretion during the remission period. At this time, actuarial analysis shows that the number of patients still in remission decreases during the first 10 months but seems to stabilize after this period. Duration of our remissions is equal to the duration of the "spontaneous" remissions taken from the literature. New treatment able to sustain the residual insulinsecretion during the remission phase (with presently can be induced frequently with our technique) are still to be found.

Sustained insulin-induced remissions of juvenile diabetes by means of an external artificial pancreas

Remission of diabetes was attempted in 12 recent acute onset ketosis-prone juvenile diabetes after short term (5 +/- 1 days) but excellent blood glucose control by the external artificial beta-cell. The comparison group comrised patients undergoing traditional treatment (n = 28). Nine (75%) persistent (over 3-14 months of duration) although partial (oral drugs required) remissions were obtained in the former group as compared to 3 (11%) in the latter group (p less than 0.05). Cases which showed remissions after insulin infusion had a plasma insulin response to IV glucagon still present before insulin infusion, and a daily urinary C-peptide excretion significantly enhanced after (p less than 0.01). Urinary C-peptide/blood glucose remained improved during the remission period. Thus, early effective treatment by means of the artificial pancreas may break the vicious circle hyperglycaemia-insulin depletion-hyperglycaemia and lead to frequent and sustained remissions of juvenile diabetes.

Influence of indigestible fibers on glucose tolerance

In eight patients exhibiting chemical diabetes mellitus with a poststimulative hypoglycemia, we observed that the pattern of the oral glucose tolerance test (OGTT) was improved when indigestible fiber was added to the oral glucose load. As compared with a standard OGTT, the peak blood glucose, expressed as per cent change from baseline, was particularly blunted by pectin or by cellulose phosphate but remained unchanged with cellulose supplementation. The time interval required to reach the blood glucose peak was significantly prolonged with pectin. The rate of blood glucose rise was reduced to a greater extent by pectin than by cellulose phosphate, which in turn was more efficient than cellulose. The blood glucose nadir expressed as per cent change from baseline was blunted by pectin, while the results were not significantly different after addition of either cellulose phosphate or cellulose. On the other hand, the plasma immunoreactive insulin did not show any significant change whether the glucose was given with or without one of the aforementioned types of fiber. From these results, it is concluded that an additional fiber intake may be of interest in the management of chemical diabetes. The use of pectin may diminish the poststimulative hypoglycemia.

[Clinical and diabetic research of the artificial extracorporeal pancreas]

With the external artificial pancreas used by the authors, blood glucose is continuously controlled by insulin delivered through an IV infusion and adjusted to two parameters: instantaneous blood glucose levels and increasing or decreasing patterns of blood glucose. The artificial pancreas can be used to treat acute diabetic disorders an to evaluate insulin needs. Furthermore, exogenous insulin homeostasis can be studied: the delay to reach an insulin effect is 18 mm +/- 2 and it remains within 28 mm +/- 2 after the infusion has been stopped; fractional insulin needs are evaluated. From these data, it appears that the efficiency of exogenous insulin exhibits a circadian rhythm.

Evaluation of exogenous insulin homoeostasis by the artificial pancreas in insulin-dependent diabetes

With the artificial pancreas used by the authors, insulin was delivered through a venous infusion and the rate of delivery was adjusted according to data provided by a continuous blood glucose monitor. After different trials we selected control algorithms integrating two parameters: instantaneous blood glucose concentration and increasing or decreasing patterns of blood glucose. A constant basal insulin infusion rate was added and improved the control of glycaemic excursions. Different parameters concerning exogenous insulin homoeostasis were determined. The delay to reach an insulin effect was 18+/-2 min and was shortened by a priming-dose at the beginning of the infusion. The insulin effect remained for 28+/-2 min after the infusion had been stopped, but differences were noted in the morning (21+/-2 min), in the afternoon (32+/-2 min) and during the night (25+/-3 min). Insulin needs were evaluated during meals. Related to the amount of carbohydrates, the doses fell from 0.53 units/hr/g of carbohydrate for breakfast to 0.15 for dinner. From these data, it appears that the efficiency of exogenous insulin exhibits a circadian rhythm.