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.

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.

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.

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.

Effect of absorbable and nonabsorbable sugars on intestinal calcium absorption in humans.

The effects of glucose, galactose, and lactitol on intestinal calcium absorption and gastric emptying were studied in 9, 8, and 20 healthy subjects, respectively. Calcium absorption was measured by using a double-isotope technique and the kinetic parameters were obtained by a deconvolution method. The gastric emptying rate was determined with 99mTc-diethylenetriaminepentaacetic acid and was expressed as the half-time of the emptying curve. Each subject was studied under two conditions: (a) with calcium alone and (b) with calcium plus sugar. Glucose and galactose increased the calcium mean transit time and improved the total fractional calcium absorption by 30% (p less than 0.02). Lactitol decreased the mean rate of absorption (p less than 0.001) and reduced the total fractional calcium absorption by 15% (p less than 0.001). The gastric emptying rate did not appear to influence directly the kinetic parameters of calcium absorption. These results show that both glucose and galactose exert the same stimulatory effect as lactose on calcium absorption in subjects with normal lactase whereas lactitol mimics the effects of lactose in lactase-deficient patients. Thus the absorbability of sugars determines their effect on calcium absorption.

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.

Hyperprealbuminemia, euthyroid hyperthyroxinemia, Zollinger-Ellison-like syndrome and hypercorticism in a pancreatic endocrine tumour.

Prealbumin, one of the main thyroxine transport proteins, has recently been shown to be a valuable immunohistochemical marker of neuroendocrine tumours. We report the case of a multisecretory pancreatic endocrine tumour whose prealbumin secretion was so high that it produced a peak on routine serum protein electrophoresis and induced a euthyroid hyperthyroxinemia. The maximal binding capacity of prealbumin for thyroxine was indeed markedly increased, whereas its affinity for this hormone was normal. The tumour was associated with gastric hyperacidity and hypergastrinemia thereby evoking a Zollinger-Ellison syndrome. The secretin stimulation test and gastrin tumoural immunohistochemistry were, however, negative. We suggest that the concomitant tumoural production of gastrin-releasing peptide was responsible for the gastric hyperacidity and hypergastrinemia. This hormone probably also accounted for a moderate hypercorticism.

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.

[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.

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.

[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 single daily doses of a pyridil-2-tetrahydrothiophene derivative (40749 RP) on 24 hour H+ activity, nocturnal acid output, gastrin and pepsinogen I profiles in duodenal ulcer patients.

40749 RP is a pyridil-2-tetrahydrothiophene derivative, belonging to a new class of gastric antisecretory drugs. We compared its effects on gastric secretion with cimetidine. Intragastric acidity, nocturnal acid output, gastrin and pepsinogen-I profiles were measured in patients with duodenal ulcer in clinical remission. A single dose of 100 mg 40749 RP reduced median 24 h gastric acidity as effectively as cimetidine 1000 mg given as four divided doses, 0.63 vs 1.6 mmol/l. Continued treatment with 40749 RP for 10 days reduced the median 24 h gastric acidity even further, to 0.006 mmol/l (p less than 0.001) and significantly increased fasting concentrations of gastrin and pepsinogen-I (p = 0.02). The incremental gastrin secretion to a standard meal was significantly increased after 10 days treatment with 40749 RP when compared with the first day of 40749 RP, or with cimetidine. These results show that 40749 RP exerts a powerful inhibitory effect on gastric acid secretion after a single 100 mg dose, and that this inhibitory effect increases with continued administration.

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.

A simple method for measurement of intestinal calcium absorption in humans by double-isotope technique.

We describe a method for the fast calculation of total fractional calcium absorption (TFCaA) by the double-isotope technique (45Ca orally and 47Ca intravenously). The gamma- and beta-activities of plasma or urine samples were measured simultaneously. 47Ca activity was obtained by a gamma-ray spectrometer after exclusion of scandium 47. The 45Ca activity was measured directly by subtracting the 47Ca plus 47Sc component from the total beta-activity. In addition, 45Ca activity was determined after 8 weeks, to allow for 47Ca and 47Sc decay. There was good correlation between these two methods of measuring 45Ca activity. TFCaA was calculated both by deconvolution taken as a reference method and from the equilibrium quotient 45Ca/47Ca observed in several blood or urine samples collected at different times. The most convenient sampling time for calculation of this ratio was reappraised, taking into account the type of solution ingested orally (water or milk). The results indicate that simultaneous counting of gamma- and beta-activities of an appropriate plasma or urine sample provides a good and rapid measure of the calcium absorption. This method is considered to be useful as a clinical tool.

[Clinical value of determining pepsinogen I]. / Intérêt clinique du dosage du pepsinogène I.

The serum values of PG I and gastrin have been established in a normal population and in several clinical diseases. The PG I is raised in duodenal, gastric, and pyloric ulcer even though the gastrin is normal. Both PG I and gastrin values are raised in renal insufficiency and the Zollinger-Ellison syndrome. The PG I is lowered in atrophic gastritis and alcoholic cirrhosis, and is at the limit of detection in Biermer anemia and total gastrectomy. Insulin and sham-feeding are stimulants for PG I release by patients with duodenal ulcer, but no correlation is observed between PG I output and PAO in the studied group. The results show that PG I is able to distinguish between associated hypergastrinemia and hypoacidity (Biermer anemia type) or a hyperacidity (Zollinger-Ellison syndrome type), and that PG I is a good indicator for gastric hypoacidity. Overlapping between normal and ulcer subjects is comparable to those obtained in acid output determinations.

Effects of lactose on intestinal calcium absorption in normal and lactase-deficient subjects.

The effect of lactose on intestinal calcium absorption was studied in 12 normal-lactase subjects and 7 lactase-deficient subjects. Calcium absorption was compared by using the double isotope technique with or without the presence of an oral load of 50 g of lactose in each subject. The kinetic parameters were measured by the deconvolution method. In the normal lactase group, the lactose prolonged the duration of absorption at a maximum rate and therefore increased the total fractional calcium absorption from 0.224 +/- 0.039 to 0.356 +/- 0.076 (p less than 0.001). In the lactase-deficient subjects, the lactose decreased the total absorption from 0.255 +/- 0.039 to 0.209 +/- 0.032 (p less than 0.005); this effect resulted in a decrease of the maximum absorption rate. There was no significant difference between the two groups when calcium was ingested alone. These results indicate that the effect of lactose on calcium absorption is dependent on intestinal lactase activity.

[Diagnosis of lactase deficiency with the expired hydrogen (H2) test]. / Diagnostic des déficits en lactase par le test de l'hydrogène (H2) expiré.

To determine the sensitivity and specificity of breath hydrogen (H2) in detecting lactase deficiency, breath H2 collected by end-expiratory sampling and capillary blood glucose were measured after ingestion of 50 g of lactose in 36 patients with biopsy-proved isolated lactase deficiency, 42 with normal lactase activity and 6 with lactase deficiency secondary to mucosal lesions. All patients had digestive symptoms clinically compatible with lactose malabsorption. The maximum increase in breath H2 concentration was more than 1.1 mumol/l (25 ppm) in all patients with isolated lactase deficiency, and less than 0.88 mumol/l (20 ppm) in 88% of patients with normal lactase activity; there were 5 false-positive results, attributed in one case to small bowel colonization and in another case to rapid transit after gastric surgery. Secondary lactase deficiency was accurately detected by neither breath H2 nor blood glucose.

Significance of duodenal disaccharidases. A comparative study of duodenal and jejunal values.

Endoscopic biopsies at the inferior duodenal flexure from 36 patients were assayed for disaccharidases. Comparative studies in 8 patients were carried out from this location and from the duodenojejunal flexure. 16 patients with lactase values under 20 U/g protein and normal histology also underwent a lactose tolerance test. Evidence is presented that the easily performed duodenal biopsies give the same information as those from the angle of Treitz, at a level about 40% under the latter. Tolerance to lactose was in close relation with the lactase level in 16 patients, the limit being at about 5 U/g protein.