PubMed Health⌕ Search

Biomedical subjects

C Monserrat

Publications and source records attributed to C Monserrat.

16 recordsLinked to original sources
PubMed2001

Automatic localization of cephalometric Landmarks.

A system for automatic detection of cephalometric landmarks is presented. Landmark detection is carried out in two steps: a line detection module searches for significant, well-contrasted lines of the image, such as the jaw line or the nasal spine. The landmark detection module uses the lines located in the first module to determine the search areas and then applies a pattern detection algorithm, based on mathematical morphology techniques. Relations between landmarks and lines are determined by means of a training process. The system has been tested for the detection of 17 landmarks on 20 images: more than 90% of the landmarks are accurately identified.

Algorithms↗
PubMed2001

A new approach for the real-time simulation of tissue deformations in surgery simulation.

Simulation of the behaviour of elastic objects in real time is one of the present objectives of computer graphics. One of its fields of application lies in virtual reality, mainly in surgery simulation systems. Models used for the construction of objects with deformable behaviour in computer graphics are known as deformable models. These have two conflicting characteristics: interactivity and movement realism. The deformable models developed up till now have promoted one characteristic to the detriment of the other. In this paper, a new approach is proposed based on boundary element methods (BEM). This is characterised by a positive equilibrium between speed and realism and great robustness. These properties along with the experimental results described in this paper permit one to assert that establishing deformable models with BEM is a reliable method to model objects in virtual reality environments for surgery simulation. In addition to that, the required elasticity parameters could be obtained experimentally through the use of a pig's liver.

Algorithms↗
PubMed2000

Use of the National Committee for Clinical Laboratory Standards guidelines for disk diffusion susceptibility testing in New York state laboratories.

Accurate antimicrobial susceptibility testing is vital for patient care and surveillance of emerging antimicrobial resistance. The National Committee for Clinical Laboratory Standards (NCCLS) outlines generally agreed upon guidelines for reliable and reproducible results. In January 1997 we surveyed 320 laboratories participating in the New York State Clinical Evaluation Program for General Bacteriology proficiency testing. Our survey addressed compliance with NCCLS susceptibility testing guidelines for bacterial species designated a problem (Staphylococcus aureus and Enterococcus species) or fastidious (Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria gonorrhoeae) organism. Specifically, we assessed compliance with guidelines for inoculum preparation, medium choice, number of disks per plate, and incubation conditions for disk diffusion tests. We also included length of incubation for S. aureus and Enterococcus species. We found overall compliance with the five characteristics listed above in 80 of 153 responding laboratories (50.6%) for S. aureus and 72 of 151 (47.7%) laboratories for Enterococcus species. The most common problem was an incubation time shortened to less than 24 h. Overall compliance with the first four characteristics was reported by 92 of 221 (41.6%) laboratories for S. pneumoniae, 49 of 163 (30.1%) laboratories for H. influenzae, and 11 of 77 (14.3%) laboratories for N. gonorrhoeae. Laboratories varied from NCCLS guidelines by placing an excess number of disks per plate. Laboratories also reported using alternative media for Enterococcus species, N. gonorrhoeae, and H. influenzae. This study demonstrates a need for education among clinical laboratories to increase compliance with NCCLS guidelines.

Anti-Bacterial Agents↗
PubMed2000

Multiresolution segmentation of three-dimensional medical images using mathematical morphology techniques.

A semi-automatic method for three-dimensional segmentation of medical images is proposed. A multiresolution representation is achieved through the application of morphological filters, which assures causality for image extrema. This allows for a compact scale space representation, in which each extremum is assigned a scale value. Interactive selection of the interesting extrema of the image is carried out, aided by this scale information and other relevant features. Extrema selected are then used as markers in three-dimensional watersheds calculation. The system has been developed and tested under low cost platforms, and can be the base for totally automatic, knowledge based segmentation systems.

Artificial Intelligence↗
PubMed2000

A new efficient method for 3D registration using human brain atlases.

In this article a new efficient method in deformable brain atlases is proposed. To achieve this goal we use the composition of two applications, an affine transformation and other one. In this second application we have used three different approaches. One approach that has been used and two new approaches. We use a set of points to be identified both in brain atlas and in patient's brain for registration. The three approach present an advantage: the mathematical solution obtained makes it to be very fast, almost immediate. Several results have been obtained and they have been classified as very satisfactory by the neurosurgeons that have tested our system.

Brain Mapping↗
PubMed1999

Fluorescence-based detection of lacZ reporter gene expression in intact and viable bacteria including Mycobacterium species.

A variety of fluorescein di-beta-D-galactopyranoside (FDG)-based substrates were evaluated for measuring beta-galactosidase expression in bacteria. One substrate, 5-acetylamino-FDG (C2FDG), performed well in all bacteria tested, including the slow growing mycobacterium, Mycobacterium bovis BCG. The sensitivity of C2FDG in intact, viable BCG was similar to that of o-nitrophenyl-beta-D-galactopyranoside in cell lysates when used to measure lacZ reporter gene activity. C2FDG was approximately 70-fold more sensitive than green fluorescent protein (GFP) in BCG when assayed in a fluorescence plate reader, and comparable to GFP when measured by flow cytometry. These assays provide an important new alternative for the rapid measurement of reporter gene expression in viable bacteria.

Bacteria↗
PubMed1999

Interactive image-guided surgery system with high-performance computing capabilities on low-cost workstations: a prototype.

We present a new frameless stereotatic system prototype that has been initially validated in functional neurosurgery operations and that makes use of an optical position tracker for image-guided neurosurgery. Several devices for tracking different surgical instruments have been designed and manufactured. These devices include an array of infrared light-emitting diodes that are tracked by three charge-coupled device cameras. The system presents several new approaches for surgery planning. For high-quality 3D images of the patient's anatomy, we have developed a parallel version of a volume-rendering algorithm, thus enabling real-time 3D anatomy manipulation on low-cost PC workstations. In order to test the accuracy of the system, the localization of the target by means of a stereotatic frame has been compared with frameless techniques, obtaining a difference of about 1 +/- 1 mm.

Algorithms↗
PubMed1999

A system for the simulation and planning of orthodontic treatment using a low cost 3D laser scanner for dental anatomy capturing.

The detection and correction of malocclusions and other dental abnormalities is a significant area of work in orthodontic diagnosis. To assess the quality of occlusion between the teeth the orthodontist has to estimate distances between specific points located on the teeth of both arches. Distance measuring is based on the observation, by the orthodontist, of a plaster model of the mouth. Gathering of information required to make the diagnosis is a time consuming and costly operation. On the other hand, obtaining and manipulation of plaster casts constitute a huge problem in clinics, due to both the large space needed and high costs associated with plaster casts manufacturing. For this problem we present a new system for three-dimensional orthodontic treatment planning and movement of teeth. We describe a computer vision technique for the acquisition and processing of three-dimensional images of the profile of hydrocolloids dental imprints taken by mean of a own developed 3D laser scanner. Profile measurement is based on the triangulation method which detects deformation of the projection of a laser line on the dental imprints. The system is computer-controlled and designed to achieve depth and lateral resolutions of 0.1 mm and 0.2 mm, respectively, within a depth range of 40 mm. The developed diagnosis software system (named MAGALLANES) and the 3D laser scanner (named 3DENT) are both commercially available and have been designed to replace manual measurement methods, which use costly plaster models, with computer measurements methods and teeth movement simulation using cheap hydrocolloid dental wafers. This procedure will reduce the cost and acquisition time of orthodontic data and facilitate the conduct of epidemiological studies.

Adult↗
PubMed1998

Corticosterone binding to tissues of adrenalectomized lean and obese Zucker rats.

The binding of corticosterone, dexamethasone and aldosterone was investigated in plasma and in homogenates of liver, kidney, brain, brown adipose tissue and visceral (periovaric) and subcutaneous white adipose tissues of Zucker lean and obese rats: intact controls, adrenalectomized and sham-operated. Corticosterone-binding globulin (CBG) accounted for most of the binding, whereas that of glucocorticoid and mineralocorticoid receptors was much lower. Plasma corticosterone levels increased in sham-operated and obviously decreased in the adrenalectomized animals. Sham-operated and adrenalectomized lean rats showed decreased plasma CBG; in the obese, CBG levels were lower than in controls and were not affected by either surgery. No variation with obesity or surgery was observed either in dexamethasone or aldosterone binding, the latter being practically zero in most samples. When expressed per unit of tissue protein, CBG activity was maximal in adipose tissues, with lowest values in brain and liver. In lean rats, tissue CBG activity decreased with either surgical treatment; no changes were observed in the obese, which also had lower CBG tissue levels. The relative lack of changes in CBG of obese rats suggests that they have lost -- at least in part -- the ability to counter-modulate the changes in glucocorticoid levels through CBG modulation, thus relying only on the control of corticosterone levels. This interpretation agrees with the postulated role of CBG modulating the availability of glucocorticoids to target cells.

Adipose Tissue↗
PubMed1997

Short-term handling of the slimming agent oleoyl-estrone in liposomes (Merlin-2) by the rat.

Female adult rats were injected in the jugular vein with oleoyl-3H-estrone incorporated into liposomes. The label rapidly disappeared from the blood, being taken up by the tissues, mainly liver, spleen and lung, which filtered most of the label. However, many other tissues, such as the heart, brown adipose tissue, adrenals and visceral fat incorporated significant amounts of oleoyl-estrone. The analysis of the form in which the label remained 10 min after the injection showed that it was hydrolysed in a large proportion even in liver and lungs. However, in most tissues (brain, brown and white - periovaric - adipose tissues and ovaries), intact oleoyl-estrone accounted for less than one quarter of all tissue label, and less than 10% in the case of subcutaneous adipose tissue and uterus. This rapid destruction of oleoyl-estrone is in agreement with the active role of this compound in the control of body weight.

Adipose Tissue↗
PubMed1997

Effect of the slimming agent oleoyl-estrone in liposomes on the body weight of rats fed a cafeteria diet.

Weaned lean Zucker rats, 21-days old, were fed a cafeteria diet for 70 days. The cafeteria diet-obese rats were infused for 28 days (using miniosmotic pumps) with oleoyl-estrone in liposomes (Merlin-2) at a dose of 3.5 mmol/day.kg. Treatment resulted in loss of body weight: 11.6% (32 g), mainly due to fat: 20.0% (8.8 g), protein 5.2% (2.0 g) and water, preventing further increases in body weight and fat storage. Untreated rats increased their body weight: 7.6% (20 g), lipid: 10.5% (4.2 g) and protein: 13.2% (4.8 g). Plasma glucose, urea, triacylglycerols and cholesterol practically did not change with treatment. Merlin-2 decreased energy intake (to 83.7%) and energy output (to 87.7%, oxygen consumption). Decreases in nitrogen intake were partly compensated by higher digestive efficiency in treated rats. The size of the nitrogen gap was higher in treated rats than in controls. Essentially, protein balance was maintained and slimming was achieved with a minimal loss of body protein. Treated rats selected less carbohydrate, in particular sugars, in their diet than controls, but consumed practically the same protein and lipid. Treatment of cafeteria diet-fed rats with oleoylestrone in liposomes results in sustained loss of body weight--mainly lipid--for up to 28 days. Nitrogen balance is maintained overall. This is achieved through lower food intake--mainly of sugars--and less marked changes in energy output.

Animals↗
PubMed1996

Oleoyl-estrone induces the loss of body fat in rats.

OBJECTIVE: Four experiments were devised to test the possible role of estrone fatty esters as adipose tissue signals carried by the blood within lipoproteins. DESIGN: Oleoyl-estrone was synthesized and incorporated in liposomes; it was administered i.v. (to mimic lipoprotein delivery) for 14-day periods using implantable osmotic minipumps. The study included the finding of oleoyl-estrone in blood lipoproteins, the correlations of the effects of body weight to the dose and the uptake of labelled oleoyl-estrone by tissues, its internalization and disposal. SUBJECTS: Normal-weight Wistar female rates were used. Pooled human blood was used as source of HDL3. MEASUREMENTS: Oleoyl-estrone was identified in rat white adipose tissue and in human blood HDL3 lipoprotein fraction. Changes in body weight, food intake, oxygen consumption, respiratory quotient and nitrogen balance were measured in chronically injected rats. The uptake and hydrolysis of oleoyl-estrone by tissues was also determined following its acute administration. RESULTS: Oleoyl-estrone induced a dose-dependent loss of weight, with decreased food intake. In 14 days, and compared with controls at the end of this period, a dose of 0.78 mumol/day induced the loss of 16.4 +/- 5.5% of body weight; the difference was maximal for doses of 15 mumol/day or higher: 24.7 +/- 3.1%. Under oleoyl-estrone treatment, body protein was preserved (positive nitrogen balances) and fat stores were wasted: lowered respiratory quotient, and deficit in energy balance; a dose of 0.78 mumol/day induced the loss of 9.6 +/- 2.2 g of total body lipids in 14 days. Most of oleoyl-estrone taken up by tissues was hydrolysed; however, in part it reached intact the cell nucleus of incubated adipocytes. Oleoyl-estrone effects were different from those of free estrone. CONCLUSION: A lipophilic pathway for oleoyl-estrone transport by lipoproteins is postulated, allowing chemical communication between tissues. Oleoyl-estrone may be directly involved in the control of body weight.

Adipocytes↗
PubMed1996

Urinary excretion of sucrose and fructose as a predictor of sucrose intake in dietary intervention studies.

The urinary excretion of sucrose, glucose, and fructose was measured in 9 healthy subjects consuming a common Italian diet and after 3 days of a low sucrose diet, in which the intake of sucrose was restricted but the other main nutrients were unmodified. After the low sucrose diet, we observed a significant drop in the average urinary excretion of sucrose, glucose, and fructose determined at four different times (8:00 and 10:00 a.m.; 3:00 and 10:00 p.m.). The average urinary excretion of fructose in the four urine samples was significantly correlated with dietary sucrose intake. We also found a significant correlation between the average urinary excretion of sucrose and dietary sucrose intake. Urinary fructose can be used as a marker of sucrose intake in dietary intervention studies aimed at studying the effect of variation of carbohydrate intake on specific cancers.

Adult↗
PubMed1994

Effect of a mixture of 15 commonly used pesticides on DNA levels of 8-hydroxy-2-deoxyguanosine and xenobiotic metabolizing enzymes in rat liver.

The level of 8-OH-2-deoxyguanosine in rat liver DNA was measured as an index of oxidative damage after treating rats for 10 days at a dose ranging from 0.75 to 10 mg/kg with a mixture of 15 pesticides (dithiocarbamate, benomyl, thiabendazole, diphenylamine, chlorthalonil, procimidone, methidathion, chlorpyrifos-ethyl, fenarimol, parathion-methyl, chlorpropham, parathion, vinclozolin, chlorfenvinphos, pirimiphos-ethyl) commonly found in foods of central Italy. At the doses of 0.75 and 1 mg/kg DNA levels of 8-OH-2-deoxyguanosine were significantly increased relative to controls, whereas at higher doses (2.5, 5, 10 mg/kg) the levels returned to control values. The administration of the pesticide mixture dose dependently reduced benzo(a)pyrene hydroxylase, N-demethylase activities, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and thiol transferase activities in the liver. The results show that the pesticide mixture induced free radical DNA damage at low doses. However, at higher doses it produced a depression of cellular metabolism, inhibiting a further expression of oxidative damage.

8-Hydroxy-2'-Deoxyguanosine↗
PubMedDate not supplied

Computer-aided periodontal disease diagnosis using computer vision.

Periodontal diseases are the major cause of tooth loss. The study of the evolution of these diseases is crucial to achieve adequate planning and treatment. Depth probing is essential to know the periodontal disease stage. In this paper we present a new system for Computer-Aided Periodontal Disease Diagnosis using computer vision. The system automates the depth probing and incorporates a colour camera fitted together with a plastic probe that automatically and exactly obtains the depth probing measure. The system has been tested by several periodontists and with 125 teeth of different patients. The differences between the values taken by the system and two periodontists have not been significant.

Absorptiometry, Photon↗