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Biomedical subjects

G Franco

Publications and source records attributed to G Franco.

At least 19 recordsLinked to original sources
PubMed1992

Cerebral glucose utilization during stage 2 sleep in man.

Using [18F]fluorodeoxyglucose method and positron emission tomography, we performed paired determinations of the cerebral glucose utilization at one week intervals during sleep and wakefulness, in 12 young normal subjects. During 6 of 28 sleep runs, a stable stage 2 SWS was observed that fulfilled the steady-state conditions of the model. The cerebral glucose utilization during stage 2 SWS was lower than during wakefulness, but the variation did not significantly differ from zero (mean variation: -11.5 +/- 25.57%, P = 0.28). The analysis of 89 regions of interest showed that glucose metabolism differed significantly from that observed at wake in 6 brain regions, among them both thalamic nuclei. We conclude that the brain energy metabolism is not homogeneous throughout all the stages of non-REMS but decreases from stage 2 SWS to deep SWS; we suggest that a low thalamic glucose metabolism is a metabolic feature common to both stage 2 and deep SWS, reflecting the inhibitory processes observed in the thalamus during these stages of sleep. Stage 2 SWS might protect the stability of sleep by insulating the subject from the environment and might be a prerequisite to the full development of other phases of sleep, especially deep SWS.

Adult↗
PubMed1992

Work coding.

Explore the source record for details and available documents.

Humans↗
PubMed1992

[Ambulatory and hemodynamic treatment of varicose veins (CHIVA cure). Revolution or regression].

Ambulatory Hemodynamic Treatment of Varicose veins (CHIVA), owing to duplex scan, is a come back to forgotten method of cutting and ligation of superficial veins which have for a long time given the proof of inefficiency. This method ignores the fundamental problems of venous insufficiency. The long dated superiority of this technic about venous preservation compared with other methods is not demonstrated. The analysis of recurrent varicose veins after surgical treatment shows that the main cause is an inadequate operative technique associated with the evolution of the basic wall failure. CHIVA-cure, starting from the opposite opinion is doing un unbelievable come back to staged ligation expecting better results. The high rate of superficial venous thrombosis and complementary acts on the residual varicose veins, only one year after the primitive surgery, don't augur well of the future.

Ambulatory Surgical Procedures↗
PubMed1991

New perspectives in biomonitoring liver function by means of serum bile acids: experimental and hypothetical biochemical basis.

The functional activity of the liver and the variety of its responses to injury makes the choice of appropriate tests of function a difficult task. Because of the highly efficient uptake of bile acids by the normal hepatocyte, the determination of serum bile acid (SBA) concentration has been proposed as a test to detect early changes of liver function not associated with cytotoxicity. Several biomonitoring studies have been carried out on subjects occupationally exposed to hepatotoxic substances, by evaluating SBAs as indicators of early liver dysfunction. Even though these studies are not exactly comparable because of the different protocols adopted, most of them show a significant increase in SBA concentrations among the exposed subjects compared with unexposed controls. Furthermore, higher prevalences of subjects with abnormal SBA concentrations occur in those exposed to mixtures of organic solvents. Increased SBA concentrations among the subjects exposed to various xenobiotics have been explained by assuming a change in function of hepatocytes. As regards the nature of the mechanisms involved in the increase in SBA concentrations, recent experimental observations pointed out that some chlorinated aliphatics were able to inhibit cell membrane ATPases and alter cytosolic calcium homeostasis. The lack of any relation, however, between exposure and SBA concentrations remains an important point to clarify and at present prevents the use of measurement of SBA concentrations as an index of effect.

Adult↗
PubMed1990

Cerebral glucose utilization during sleep-wake cycle in man determined by positron emission tomography and [18F]2-fluoro-2-deoxy-D-glucose method.

Using the [18F]fluorodeoxyglucose method and positron emission tomography, we studied cerebral glucose utilization during sleep and wakefulness in 11 young normal subjects. Each of them was studied at least thrice: during wakefulness, slow wave sleep (SWS) and rapid eye movement sleep (REMS), at 1 week intervals. Four stage 3-4 SWS and 4 REMS fulfilled the steady state conditions of the model. The control population consisted of 9 normal age-matched subjects studied twice during wakefulness at, at least, 1 week intervals. Under these conditions, the average difference between the first and the second cerebral glucose metabolic rates (CMRGlu was: -7.91 +/- 15.46%, which does not differ significantly from zero (P = 0.13). During SWS, a significant decrease in CMRGlu was observed as compared to wakefulness (mean difference: -43.80 +/- 14.10%, P less than 0.01). All brain regions were equally affected but thalamic nuclei had significantly lower glucose utilization than the average cortex. During REMS, the CMRGlu were as high as during wakefulness (mean difference: 4.30 +/- 7.40%, P = 0.35). The metabolic pattern during REMS appeared more heterogeneous than at wake. An activation of left temporal and occipital areas is suggested. It is hypothetized that energy requirements for maintaining membrane polarity are reduced during SWS because of a decreased rate of synaptic events. During REMS, cerebral glucose utilization is similar to that of wakefulness, presumably because of reactivated neurotransmission and increased need for ion gradients maintenance.

Adult↗
PubMed1990

The incidence of post-operative urinary tract infection in patients with ureteric stents.

Despite the many advantages provided by the ureteric stent, it produces a foreign body reaction and increases the risk of infection. We undertook a study on the rate of infection in a group of paediatric patients with ureteric stents; 40 ureteric stents, 6 to 9 F, were used in 36 children undergoing the following procedures: 18 pyeloplasties, 20 antireflux ureteric reimplantation and 2 uretero-rectal anastomoses. Only patients with sterile urine pre-operatively were included in the study. All received antibiotic cover in the post-operative period. Positive urine cultures were found in only 3 patients (7.5%). In spite of this low incidence, the urine specimens collected from all children 1 month after removal of the stent showed a much higher incidence of infection. It was concluded that ureteric stenting is a safe procedure with a low rate of infection provided that antibiotic cover is given.

Child↗
PubMed1990

[D-glucaric acid. A new method proposed to investigate damage from exposure to anesthetic gas and vapors].

Acute exposure and hepatotoxicity following full anesthetic doses is controversial, despite various experimental trials. On the other hand, microsomial enzyme induction following the chronic use of anesthetic gases and vapours, even with minimal metabolism, has been established. Therefore, there is increasing interest in the field of prevention to develop techniques and instruments to minimize pollution of anesthetic vapours and screening methods to detect early liver-damage. We have evaluated the reliability of D-Glucaric Acid test in monitoring microsomial enzyme induction after anesthesia. We evaluated urinary excretion of D-Glucaric Acid before and after exposure to anesthetic gases in 53 subjects, including medical personnel and patients. Statistical analysis of these data confirm the usefulness of this technique to assess acute liver damage in patients undergoing general anesthesia (postoperative increase of 10.5 microns/l as average value of urinary acid excretion, chi 2 = 9.8; p less than 0.01). This technique is also valuable in demonstrating damage in operating room personnel due to chronic exposure (base values greater than 12 microns/l in anesthesiologists with a 9 microns/l increase at the end of surgical intervention, chi 2 = 8.1; p less than 0.01). Data of patients submitted to local anesthesia are more difficult to interprete. They presented a decrease in acid urinary excretion (less than 10 microns/l; chi 2 = 1.93; p less than 0.2) probably due to hemodynamic changes which occurred during spinal block or due to degree of sedation related to de-afferentation itself.

Adult↗
PubMed1989

Occupational exposure to anaesthetics: liver injury, microsomal enzyme induction and preventive aspects.

Apart from a risk excess of liver disease among operating theatre personnel and of spontaneous abortion in women exposed during pregnancy, no definitive conclusion has been drawn as regards health impairment among anaesthesiology staff. Hepatotoxicity has been detected in experimental and epidemiological studies, suggesting a close relationship between liver disease and anaesthetics, particularly halogenated hydrocarbons (halothane and isoflurane) and nitrous oxide. The liver microsomal enzyme system has received particular attention in order to clarify the mechanism involved in anaesthetics hepatotoxicity and an increased microsomal enzyme activity has been observed in experimental conditions and in humans (both patients treated with anaesthetic mixture and anaesthesiology staff). The prevention of adverse health effect among workers of anaesthesiology staff, is based on (i) the use of less toxic anaesthetics and (ii) the control of working conditions of staff. Attention is focused on biological monitoring by means of indicators, which reflect not only the environmental pollution but can be regarded as liver response of anaesthetics exposed workers. This inductive effect is commonly considered the earliest sign caused by exposure to several chemicals and may be evaluated by means of biomarkers, among which the measure of urinary D-glucaric acid excretion is a well established non invasive tool.

Anesthetics↗
PubMed1989

[Recent findings on the epidemiological and experimental aspects of the measurement of serum bile acids in occupational exposure to xenobiotics].

The functional activity of the liver and the variety of its responses to injury makes the choice of appropriate tests a difficult task. However, because of the highly efficient uptake of bile acids by the normal hepatocyte, the determination of serum bile acids (SBA) concentration has been proposed as a test to detect early changes of liver function not associated to cytotoxicity. Several studies of biomonitoring subjects occupationally exposed to hepatotoxic substances have been carried out by evaluating total SBA or primary SBA, as indicators of early liver dysfunction. Even though these studies are not completely comparable because of the different protocols adopted, most of them reveal a significant increase of SBA concentrations among the exposed subjects in respect of unexposed controls. Furthermore, higher prevalences of subjects exposed to organic solvents mixture with abnormal SBA concentrations in respect of controls have been observed. Increased serum bile acids concentrations among the subjects exposed to a variety of xenobiotics have been explained as a change in hepatocyte function, particularly in one of the steps involved in bile acids transport. However, the lack of any relationship between the indices of doses and SBA concentrations remains an important point to clarify. This fact could be interpreted as a consequence of the delayed biological effect responsible for increased serum bile acids during the exposure. As regards the nature of the mechanisms involved in the increase of SBA concentrations, recent observations pointed out that some chlorinated aliphatics were able to inhibit cell membrane ATPases.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Unilateral primary vesico-ureteral reflux: uni- or bilateral reimplantation?].

The need of bilateral reimplantation in unilateral reflux is still stressed by some authors. The following represents the rationale for this surgical management. 1. correction of unilateral reflux may increase bladder pressure and in this way induce a contralateral reflux; 2. the operation on one side may lead to changes in the muscles and cause reflux on the opposite one; 3. reflux, though unilateral, is the result of a malformation involving the whole trigone. Nevertheless, the authors regard as unjustified the reimplantation of a normal ureterovesical junction being in-acceptable the risk, even if low, of operative failure on a ureter without reflux. Literature data show an incidence of contralateral reflux after unilateral reimplantation of 11-32%. Such incidence, however, tends to decrease (1.9-20%) one year after the operation due to the spontaneous resolution of reflux in most of the cases. The grade of reflux was low (I-II grade) in the majority of cases. The authors report on 38 cases of unilateral primitive vesico-ureteral reflux who underwent unilateral ureteral reimplantation between 1981 and 1982. Minimum follow-up was 2 years. After surgery, contralateral reflux occurred in 4 cases (10.5%) but it spontaneously subsided within 3 years in all of them. Contralateral reflux was asymptomatic in 3 cases and in no cases caused renal scars. The authors conclude that unilateral ureteral reimplantation is the procedure of choice in children with unilateral reflux. Bilateral reimplantation, however, will be performed in patients with bilateral reflux who showed disappearance of reflux on one side before the operation.

Adolescent↗
PubMed1988

[Tutorial systems of computer-assisted self-instruction. A review].

Recent trends of pedagogy point out the importance of self-learning, which represents one of the applied models of mastery learning. This article reviews the characteristics of self-learning methods based on the use of computer. Computer aided instruction (CAI) systems include tutorials, drill & practice, evaluation, simulation programs. Particularly, tutorials are considered and compared with other learning methods. Their basic requirements are defined, especially the necessity to be interactive so that students could participate in the instructional process. Other aspects, regarding quality, help facilities, retrieval facilities, utilization easiness, interest of students, efficacy are considered. However, CAI systems do not completely substitute traditional teaching methods: they are regarded as being complementary to them and innovative, and as making learning more interesting and gratifying for the students.

Computer-Assisted Instruction↗
PubMed1988

[Ultrasonic tomography of the abdominal vessels].

For a long time echotomography just was interested in big vessels as precious anatomic guide, to delimit pancreas, to cut up liver or to situate ganglion or tumour. The improvement of technics, and particularly real time sonography coupled with continuous wave or pulsed doppler, have permitted to step over the next stage which is to recognize the proper lesions of the vessels. The probes available to perform abdominal vessels investigations have a frequency between 3 and 7.5 MHZ, and are chosen according to the morphology of the patient; in our experience in most cases sectorial probes are preferred. Except emergency situations simple preparation as diet is desirable. Aorto-iliac and visceral arteries, vena cava, renal veins, subhepatic and portal veins are generally seen. The diagnosis of stenosis, obliteration or aneurysm of big abdominal arteries, thrombosis or compression of veins are permitted by association of the morphological information given by real time and hemodynamic findings of doppler.

Abdomen↗