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At least 415 records · Page 23Linked to original sources
PubMed1999

Laparoscopic splenectomy: optimal vascular control using the lateral approach and ultrasonic dissection.

BACKGROUND: Intraoperative bleeding is the main complication and main cause of conversion to open surgery during laparoscopic splenectomy (LS). We present the advantages of the lateral approach and the use of the ultrasonic shears (US) for achieving a safer vascular control. METHODS: We have performed a total of 48 LS using several approaches. In our initial experience 10 patients underwent surgery with an anterior approach. In the second series of 18 patients, we used a manually assisted procedure. In the last 20 patients, we employed a technique with a full lateral position. Only three ports have been used. The major part of the dissection was conducted from behind, thus allowing a safer vascular control. The division of short gastric vessels and lower pole vessels was performed using US. The main vascular pedicle was stapled. The spleen was removed through a short Pfannenstiel incision. There were 9 males and 11 females with a mean age of 36 years (range, 18-71 years). Fourteen had immune thrombocytopenic purpura (ITP); two had an HIV-infection-related purpura; two had an autoimmune hemolytic anemia; and two had a spherocytosis. RESULTS: All the 20 LS were completed. The average splenic weight was 274 g (range, 162-1,400 g). In all but one patient, the intraoperative blood loss was less than 60 ml, and was none in six patients (average, 51 ml). In our initial series of 10 patients surgically treated with an anterior approach, the average blood loss was 180 ml, and it was 230 ml in the series of hand-assisted procedures. The average operative time was 127 min (range, 70-220 min), including the time required by the change of position and the Pfannenstiel incision. There was no mortality. All but one patient had an uneventful postoperative course. The HIV-infected patient had a severe postoperative pancreatitis. In those patients with an uncomplicated course, the average postoperative stay was 4.3 days (range, 2-8 days). CONCLUSIONS: The lateral position with a posterior approach to splenic vessels allows for safe vascular control. The use of US results in a gain of time and safety. The average intraoperative bleeding of this series is much lower than that observed in our previous experience and in other published series.

Adolescent↗
PubMed1975

Integral control in accommodation.

Models of the accommodation system available inthe literature may be classified as proportional controller, optimal bang-bang controller and pure integral controller types. Each of these models explains only some aspects of the experimental behavior of the system and conflicts with other experimental observations. Based on two different experiments in which the built-in phyiological feedback loop has been opened, a leaky-integrator element is proposed for the accommodation controller. This element appears to resolve the conflict between the proportional and integral controller models and also explains the experimental observations better than any of the existing models.

Accommodation, Ocular↗
PubMed1986

Mathematical modelling accounting for discrepancies between blood levels and pharmacodynamic effects of a drug. Application to the numerical optimization of tertatolol.

In this paper we propose a non-linear model for explaining the relation between doses, blood levels and pharmacodynamic effects. Several models are examined and a functional relation (without derivatives or integrals) is retained. From there the medical system is optimized by using optimal control methods. In practice, optimal doses and times are numerically determined for the drug tertatolol.

Adult↗
PubMed2006

The development of a computer model for a fixed bed gasifier and its use for optimization and control.

The development of a mathematical model of a fixed-bed gasifier is described. The model was used for studies of the stationary performance of the gasifier and the results were compared to experimental results. The model was also used in an effort to identify an efficient control strategy for the operation during load changes. The resulting strategy was very simple and has been implemented in an unmanned, automatically controlled, power plant that was operated for over 3000h. The mathematical model was based on conservation of mass and energy in a simple one-dimensional flow, chemical equilibrium in the gas phase, and a Langmuir-Hinshelwood correlation describing the reaction kinetics in the char. The results of the thermo-gravimetric analysis experiments required to determine the reactivity for char of beech as a function of temperature, gas composition and conversion ratio of the char are presented.

Carbon↗
PubMed2006

Interstitial radiation therapy for early-stage nasal vestibule cancer: a continuing quest for optimal tumor control and cosmesis.

INTRODUCTION: This article reports on the effectiveness, cosmetic outcome, and costs of interstitial high-dose-rate (HDR) brachytherapy for early-stage cancer of the nasal vestibule (NV) proper and/or columella high-dose-rate (HDR). METHODS AND MATERIALS: Tumor control, survival, cosmetic outcome, functional results, and costs were established in 64 T1/T2N0 nasal vestibule cancers treated from 1991-2005 by fractionated interstitial radiation therapy (IRT) only. Total dose is 44 Gy: 2 fractions of 3 Gy per day, 6-hour interval, first and last fraction 4 Gy. Cosmesis is noted in the chart by the medical doctor during follow-up, by the patient (visual analog scale), and by a panel. Finally, full hospital costs are computed. RESULTS: A local relapse-free survival rate of 92% at 5 years was obtained. Four local failures were observed; all four patients were salvaged. The neck was not treated electively; no neck recurrence in follow-up was seen. Excellent cosmetic and functional results were observed. With 10 days admission for full treatment, hospital costs amounted to euro5772 (7044 US dollars). CONCLUSION: Excellent tumor control, cosmesis, and function of nasal airway passage can be achieved when HDR-IRT for T1/T2N0 NV cancers is used. For the more advanced cancers (Wang classification: T3 tumor stage), we elect to treat by local excision followed by a reconstructive procedure. The costs, admission to hospital inclusive, for treatment by HDR-IRT amounts to euro5772 (7044 US dollars). This contrasts substantially with the full hospital costs when NV cancers are treated by plastic reconstructive surgery, being on average threefold as expensive.

Brachytherapy↗
PubMed2003

Techniques to optimize vascular control during laparoscopic donor nephrectomy.

OBJECTIVES: To review our experience with laparoscopic donor nephrectomy for kidney transplantation and describe our technique of vessel ligation. METHODS: We retrospectively analyzed the method of renal artery and vein control during the 97 laparoscopic donor nephrectomies performed at the University of California, San Francisco, since November 1999. In addition, we examined both donor and recipient outcomes after nephrectomy and transplantation in this cohort. RESULTS: Currently, we ligate the renal artery and renal vein using a single Hem-o-lok polymer clip and a single Endo-TA stapler, respectively, and divide the vessels using scissors without securing the graft-side vessels. In contrast to using the Endo-GIA stapler, there is no need to trim staples (approximately 5 mm) from the vessels before anastomosis. Excellent vessel length was achieved in all cases without donor complications, and 99% of recipients had long-term graft function. The only major complications (blood transfusion, conversion to open surgery) occurred early in the series when we used the Endo-GIA stapler to control the vessels. CONCLUSIONS: Although adequate vessel length is typically obtained during left donor nephrectomy, additional length can be achieved using our modification. This may facilitate right donor nephrectomy and help reduce complications, potentially increasing the recovery of right kidneys for transplantation. In addition, performing vessel ligation and division in separate steps is simple, does not change ischemic time, and appears to increase safety.

Anastomosis, Surgical↗
PubMed1998

Formulation optimization of controlled release diclofenac sodium microspheres using factorial design.

Diclofenac sodium is an ideal candidate for incorporation in a controlled release device to diminish its adverse effects after oral administration. Microspheres were prepared by using sodium alginate as a polymer and CaCl2 as a cross-linking agent. In this investigation, 3(3) full factorial design was used to investigate the joint influence of the three variables: the stirring speed (X1), concentration of CaCl2 (X2) and % of heavy liquid paraffin in a blend of heavy and light liquid paraffin in the dispersion medium (X3) on the time of 80% drug dissolution (t80). Potential variables such as concentration of sodium alginate and drug: sodium alginate ratio were kept constant in the experimental design. A statistical model with significant interaction terms is derived to predict t80. The results of multiple linear regression analysis and F-statistics revealed that for obtaining controlled drug release, the microspheres should be prepared using relatively lower stirring speed, higher concentration of CaCl2 and higher percentage of heavy liquid paraffin in the dispersion medium. The X1X2 and X2X3 interactions were found to be statistically significant in nature. A response surface plot is presented to show the effects of X1, X2 and X3 on t80. The drug was released by diffusion of anomalous type. A model was validated for accurate prediction of drug release profile. Acceptable batches were identified in the experimental design with constraints on percentage drug released in 1, 6 and 8 h.

Alginates↗
PubMed1995

Perceived behavioural control, unrealistic optimism and dietary change: an exploratory study.

In the context of five dietary changes conducive to reductions in fat consumption, a short questionnaire was constructed to examine the applicability of the theory of planned behaviour and to assess the presence of the phenomenon of "unrealistic optimism". An extension to the theory of planned behaviour was also included, in the form of a "self-identity" measure assessing identification with concern about the health consequences of diet. The questionnaire was completed by 612 members of the general public at three different locations in the U.K. The findings indicate some support for the applicability of the theory of planned behaviour, with the measure of "self-identity" producing some additional independent effects. Evidence of unrealistic optimism concerning diet-related health risks was found, with greater optimism being significantly related to lower relative consumption estimates of "unhealthy" foods. The findings are discussed in the context of implications for health promotion.

Adolescent↗
PubMed1991

Slot osteosynthesis technique (SLOT) for sagittal ramus split osteotomies. A method to optimize occlusal control and condylar seating.

In the technique presented, a specially designed drill and bone holding forceps are used. These enable a horizontal slit to be cut in the condyle-bearing segment, at the site of the largest contact surface. One lag-screw is tightened in the centre of the slit at each side. By releasing the IMF (intermaxillary fixation) and untightening one or both screws, the condylar segments can be repositioned and the occlusion corrected before inserting the other tandem screws.

Bone Screws↗
PubMed1999

Intra-familial distribution of Fusobacterium nucleatum strains in healthy families with optimal plaque control.

Fusobacterium nucleatum, a Gram-negative anaerobic rod associated with periodontal disease, is also found in healthy individuals and is considered part of the indigenous oral microflora. Although intra-familial transmission of periodontal pathogens has been documented, there are no data relating transmission of F. nucleatum. This study investigated the distribution of F. nucleatum strains in 4 strictly healthy families. 32 F. nucleatum strains were isolated from 19 individuals (8 parents and 11 children aged 1-13 years). DNA was extracted and digested with the restriction endonucleases EcoRI, TaqI and HindIII. The digests were separated by electrophoresis through 0.8% agarose gels at 40 V overnight, in TBE buffer containing 1 microg/ml ethidium bromide, and photographed. The DNA was transferred to nylon filters by Southern blotting and hybridized with a digoxigenin labelled E. coli rRNA probe (Kit Dig DNA Labelling mixture - Boehringer). Probed DNA was visualized colorimetrically (CSPD Luminescent Detection Kit Boehringer) and photographed (Amersham). We found that 10/11 children shared identical ribotypes with at least one of their respective parents. Some of the children also harbored a unique additional ribotype. On the basis of indistinguishable restriction endonuclease and ribotype patterns these results support the hypothesis that intra-familial transmission of F. nucleatum is possible.

Adolescent↗