Nicotine induced haemodynamic changes during cigarette smoking and nicotine gum chewing: a placebo controlled study in young healthy volunteers.

Because cigarette smoking is a definite risk for the development of cardiovascular disease and nicotine induced vasoconstriction may be a possible pathogenetic factor the haemodynamic effects of smoking cigarettes with high or low nicotine content were compared with those induced by chewing nicotine gum in a placebo controlled, crossover study in six healthy volunteers. The three stimuli induced similar increases in heart rate (about 20%) and systolic blood pressure (about 7%) and a decrease in digital blood flow. Although the mean haemodynamic changes parallelled the mean plasma nicotine concentration increases, no correlation was found between them when the individual values were considered. It is concluded that the nicotine induced haemodynamic changes probably occur as a result of the (local) release of vasoactive mediators such as adrenaline or noradrenaline after a threshold plasma nicotine concentration has been reached. Such a threshold may explain the large interindividual variability in susceptibility to smoking induced cardiovascular diseases.

Clinical applicability of robot-guided contact-free laser osteotomy in cranio-maxillo-facial surgery: in-vitro simulation and in-vivo surgery in minipig mandibles.

Laser was being used in medicine soon after its invention. However, it has been possible to excise hard tissue with lasers only recently, and the Er:YAG laser is now established in the treatment of damaged teeth. Recently experimental studies have investigated its use in bone surgery, where its major advantages are freedom of cutting geometry and precision. However, these advantages become apparent only when the system is used with robotic guidance. The main challenge is ergonomic integration of the laser and the robot, otherwise the surgeon's space in the operating theatre is obstructed during the procedure. Here we present our first experiences with an integrated, miniaturised laser system guided by a surgical robot. An Er:YAG laser source and the corresponding optical system were integrated into a composite casing that was mounted on a surgical robotic arm. The robot-guided laser system was connected to a computer-assisted preoperative planning and intraoperative navigation system, and the laser osteotome was used in an operating theatre to create defects of different shapes in the mandibles of 6 minipigs. Similar defects were created on the opposite side with a piezoelectric (PZE) osteotome and a conventional drill guided by a surgeon. The performance was analysed from the points of view of the workflow, ergonomics, ease of use, and safety features. The integrated robot-guided laser osteotome can be ergonomically used in the operating theatre. The computer-assisted and robot-guided laser osteotome is likely to be suitable for clinical use for ostectomies that require considerable accuracy and individual shape.

Calcium absorption from milk in lactase-deficient subjects.

Intestinal calcium absorption from milk containing lactose (+) and from another containing glucose (-) was studied in eight patients with normal lactase (NL) and seven lactase-deficient (LD) subjects to determine if lactase deficiency is implicated in Ca absorption. The results were compared with data obtained from Ca ingestion in a water solution. Ca absorption was measured by a double-isotope technique and the kinetic indices were obtained by a deconvolution method. With (-), Ca absorption was identical in NL and LD subjects and slightly higher than with water solution (15%, NS). With (+), Ca absorption in NL subjects was identical with that from water solution; in LD subjects it increased (23%, p less than 0.02). These data indicate that: Ca is absorbed equally well from milk as from water solution; (+) favors Ca absorption in LD subjects, which suggests that milk ingestion might be encouraged in LD subjects to avoid Ca deficiency; and (-) should be a valuable alternative for lactose-intolerant patients.

Comparison of the effect of medium-chain and long-chain triacylglycerols on calcium absorption in healthy subjects.

BACKGROUND: The absorption efficiency of calcium in humans is low. Some studies in infants have shown that calcium absorption can be increased by adding medium-chain triacylglycerols to the formula diet. OBJECTIVE: The effect of medium- and long-chain triacylglycerols on calcium absorption was studied in 18 healthy, young men. The results were compared with data obtained from calcium ingestion of a protein-carbohydrate formula devoid of triacylglycerols. DESIGN: Calcium absorption was measured by using a double-isotope technique and the kinetic parameters were obtained by using a deconvolution method. RESULTS: The total fractional calcium absorption measured in the presence of medium-chain triacylglycerols (0.236 +/- 0.016) or from a protein-carbohydrate formula without triacylglycerols (0.235 +/- 0.012) was not significantly different. The same result was observed with long-chain triacylglycerols (0.309 +/- 0.026) and the protein-carbohydrate formula (0.275 +/- 0.012). No kinetic parameters were significantly different regardless of the diet (protein-carbohydrate, medium-chain triacylglycerol, or long-chain triacylglycerol). This suggests that the same mechanism for calcium absorption was operative. CONCLUSIONS: Triacylglycerols had no direct effect on calcium absorption from a protein-carbohydrate formula in healthy subjects. These data do not support the use of medium-chain triacylglycerols as adjuvants to increase the absorption of calcium in healthy adults.

Glycaemic response and hydrogen production to blenderised and polymeric enteral nutrition formulas.

Complete enteral nutrition preparations include blenderised formulas based on natural foods with some fibre content and also low-residue polymeric formulas. This study examines the effect of the different fibre content of two commercial formulas (6.4 g/l and 0.25 g/l) on glycaemic and insulin response and hydrogen production in the colon during constant rate administration in 11 normal subjects. No difference in serum glucose and insulin levels was found. No rise in hydrogen production was detected with either formula suggesting no carbohydrate malabsorption. The quantity or nature of fibre present in blenderised formulas does not modify the pattern of carbohydrate absorption compared to a low-residue polymeric formula. However, this does not preclude other possible physiological effects of fibre content upon gastrointestinal motility and function.

Effect of Ca2+, Mg2+, NaN3, cholinergic agents, and gastrointestinal hormones on the guanylate cyclase from guinea pig gastric mucosa.

Guanylate cyclase in the guinea pig fundic mucosa occurred in two enzymatic forms: a "soluble" form and a particulate form. The mean basal activity of the soluble fraction measured in the presence of 300 micrometer guanosine-5'-triphosphate and 5 mM MnCl2 was 72.6 +/- 5.3 pmoles of cyclic GMP per mg of protein per min. Guanylate cyclase activity was dependent on Mn2+; it was increased by sodium azide (NaN3), CaCl2, cysteine, secretin, and cholecystokinin, but it was not influenced by gastrin, histamine, cholinergic esters, prostaglandins E1 and A1. NaN3 (1 mM) decreased the apparent Km for MnCl2 and potentiated the effects of MgCl2. The activity of the particulate fraction represented about 14% of that of the supernatant fraction. The guanylate cyclase activity of that fraction was not modified by NaN3, gastrin, cholinergic agents, secretin, or cholecystokinin. Cysteine inhibited its activity. These data do not support the hypothesis that cyclic GMP acts as a second messenger for the action of cholinergic agents and gastrin in the guinea pig gastric mucosa.

Action of H1 and H2 inhibitors on the response of histamine sensitive adenyly cyclase from guinea-pig mucosa.

In the guinea-pig, it has been shown that homogenates of mucosa from the fundus contain an adenylyl cyclase system that is activated by histamine as well as by prostaglandins PGE1 and PGA1. The effects of burimamide, an H2-inhibitor, and mepyramine and chlorpheniramide, both H1-inhibitors, were tested. Both H1 and H2 inhibitors behaved kinetically as competitive inhibitors of histamine, but the Km derived for burimamide (2.5 - 4.1 . 10(-5)) was significantly lower than that for either chlorpheniramine (0.9 - 1.9 . 10(-4)) or mepyramine (1.3 - 1.4 . 10(-4)). On the other hand none of the three inhibitors influenced the cyclase activation by PGE1 and PGA1. These results suggest that there are at least two types of receptors in the preparation studied, one responsive to histamine and the other to the prostaglandins, and that the specificity of H1- and H2-receptors is not absolute in the broken cell preparation.

[Incidence of lactase deficiency in patients with involution osteoporosis and in normal subjects. Its effect on the nutritional intake of calcium and phosphorus]. / Incidence de la déficience en lactase chez les patientes atteintes d'ostéoporose d'involution et chez les sujets normaux. Son influence sur l'apport alimentaire en calcium et en phosphore.

The incidence of lactase deficiency, evaluated by means of a lactose absorption test with blood glucose measurements, was compared in a group of 58 women suffering from postmenopausal osteoporosis and a control group of 51 normal women of the same age and ethnic origin. In the patients suffering from osteoporosis, the examination was completed by a glucose-galactose absorption test and in the control group by a hydrogen breath test. The prevalence of lactase deficiency is of approximately the same magnitude in the two groups (25.8% and 33.3% respectively). Dietary investigations showed a calcium intake superior to 1 g per day in only 40% of the osteoporotic patients, this deficiency being more important in cases where lactase deficiency was observed than in those showing normal lactose absorption. The influence of lactose malabsorption on the calcium balance, and the role of the latter in the pathogenesis of osteoporosis, are discussed.

[The effect of lactitol on the production of expired hydrogen in normal subjects]. / Effet du lactitol sur la production d'hydrogène expiré chez l'homme normal.

In man, unabsorbed disaccharide lactitol is fermented by colonic flora with an H2 breath production proportional to the absorbed quantity. The osmolality of the ingested solution is without effect either on the oro-cecal transit time and the time of H2 peak, or on the output and peak value of H2 expired. The intestinal symptoms seemed less prominent with slighter osmolality. The beginning of H2 production and the amount of H2 recorded varied widely between different subjects and in the same subject. It is thus important to consider this variability when measuring transit time and evaluating the amount of unabsorbed sugar. The comparison between two analogous doses of lactitol and lactulose (Duphalac) shows lower H2 production with lactulose, but clinical symptoms are slightly more pronounced. The glycemic peak was significantly higher for lactulose than for lactitol.

Effects of topical laryngeal lidocaine on sympathetic response to rigid panendoscopy under general anesthesia.

The sympathetic response to rigid bronchoscopy, laryngoscopy and esophagoscopy, performed under general anesthesia with isoflurane, was examined in patients who either received 5 ml of 2% lidocaine (n = 7) or 5 ml of saline (n = 7), sprayed on larynx and upper trachea under direct laryngoscopy, 2 min before the introduction of the rigid bronchoscope. Blood pressure, heart rate and plasma catecholamine and lidocaine levels were measured at specific time points of the study. Topical lidocaine led to a rapid and prolonged increase in plasma lidocaine levels. Patients treated with lidocaine showed a small but significant decrease in plasma epinephrine levels from baseline following endotracheal intubation and extubation, as compared to the saline control group. Blood pressure and heart rate response during rigid panendoscopy, isoflurane requirements and time interval from termination of panendoscopy to extubation were not different between the two groups. However, in contrast to the control group, patients who had received lidocaine had no significant rise in blood pressure and heart rate from baseline following the introduction of the rigid bronchoscope. The benefit of this moderate hemodynamic stabilizing effect of lidocaine has to be weighted against the risk of decreased protective airway reflexes due to topical laryngeal lidocaine during recovery from anesthesia.

[The intestines: an endocrine gland with multiple secretions]. / L'intestin: glande endocrine aux sécrétions multiples

The endocrinology of the digestive system has been a stimulating area of research for 15 years. Studies have shown that the intestine, with the many hormones it secretes, is to be considered an endocrine gland per se. The questions surrounding the nature, origin and functions of these hormones, and their role in human clinical medicine, are discussed. The answers, although incomplete and provisional, open highly interesting perspectives for the gastroenterologist.

Effect of trestatin, a new inhibitor of pancreatic alpha-amylase, on starch metabolism in man.

The effect of two doses (3 mg and 10 mg) of the inhibitor of pancreatic alpha-amylase trestatin on the metabolism of an oral load of 75 g of starch was observed in healthy human subjects. The mean elevation of plasma glucose over the 4 h following the load was markedly reduced both with 10 mg (mean +/- s.e.m.: 1.4 +/- 1.2 mg/dl) and with 3 mg of trestatin (7.2 +/- 2.0 mg/dl) when compared to placebo (19.5 +/- 5.1 mg/dl) (P less than 0.01 in both cases). The mean elevation of plasma insulin was decreased with both 10 mg (mean +/- s.e.m.: 1 +/- 1 microU/ml) and 3 mg of trestatin (6 +/- 2 microU/ml) when compared to placebo (20 +/- 4 microU/ml) (P less than 0.01 in both cases). Suprabasal glucose oxidation, measured by indirect calorimetry, was markedly decreased by trestatin (mean +/- s.e.m.: 2.5 +/- 1.1 g/4 h with 10 mg of trestatin versus 12.0 +/- 2.0 g/4 h with placebo, P less than 0.001). To examine whether trestatin had any action on alpha-1-4 glycosidase activity, an oral load of 100 g sucrose together with either 50 mg trestatin or with a placebo was administered to four healthy human subjects. Trestatin was observed to have only few effects on plasma glucose and insulin levels following sucrose ingestion. This suggests that its main site of action is at the alpha-amylase level. Breath hydrogen was shown to increase after ingestion of starch plus trestatin at the two doses studied. It is concluded that trestatin is a powerful inhibitor of pancreatic alpha-amylase which could be of great help in the dietary management of diabetic patients.

Comparison between clonidine and epinephrine admixture to lidocaine in brachial plexus block.

The admixture of clonidine or epinephrine to lidocaine for brachial plexus block was studied with regard to duration of block, postoperative analgesia, and plasma concentrations of lidocaine. Thirty-three patients of ASA physical status I and II received an admixture of either clonidine (150 micrograms; n = 15) or epinephrine (200 micrograms; n = 18) to 40 mL of 1% lidocaine in a randomized, double-blind fashion. Bone surgery predominated in those patients receiving clonidine and soft-tissue surgery in those receiving epinephrine (P less than 0.05). Onset and duration of block were not different between the groups. With the admixture of clonidine, fewer patients were completely pain free for greater than 12 h (13.3%) and pain scores (visual analogue scale 0-10) were higher 6 h after the block (median 4; range 0-6) than with epinephrine (61.1%; median 2; range 0-7, respectively; P less than 0.05). In patients who had received clonidine, peak plasma concentrations of lidocaine were higher (10.29 +/- 2.96 mumol/L) and occurred earlier (23.7 +/- 9.3 min; mean +/- SD) than in those treated with epinephrine (6.9 +/- 1.71 mumol/L; 72.5 +/- 56.2 min; P less than 0.05). This indicates the absence of a local vasoconstrictor effect of clonidine and implies a reduced margin of safety with regard to local anesthetic toxicity. Although clonidine does not offer advantages compared with epinephrine, it may be a useful adjunct to local anesthetics in those patients in whom the administration of epinephrine is contraindicated.