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Biomedical subjects

A Moreno

Publications and source records attributed to A Moreno.

At least 541 records · Page 30Linked to original sources
PubMedDate not supplied

Towards a method for automated classification of 1H MRS spectra from brain tumours.

Recent studies have shown that MRS can substantially improve the non-invasive categorization of human brain tumours. However, in order for MRS to be used routinely by clinicians, it will be necessary to develop reliable automated classification methods that can be fully validated. This paper is in two parts: the first part reviews the progress that has been made towards this goal, together with the problems that are involved in the design of automated methods to process and classify the spectra. The second part describes the development of a simple prototype system for classifying 1H single voxel spectra, obtained at an echo time (TE) of 135 ms, of the four most common types of brain tumour (meningioma (MM), astrocytic (AST), oligodendroglioma (OD) and metastasis (ME)) and cysts. This system was developed in two stages: firstly, an initial database of spectra was used to develop a prototype classifier, based on a linear discriminant analysis (LDA) of selected data points. Secondly, this classifier was tested on an independent test set of 15 newly acquired spectra, and the system was refined on the basis of these results. The system correctly classified all the non-astrocytic tumours. However, the results for the the astrocytic group were poorer (between 55 and 100%, depending on the binary comparison). Approximately 50% of high grade astrocytoma (glioblastoma) spectra in our data base showed very little lipid signal, which may account for the poorer results for this class. Consequently, for the refined system, the astrocytomas were subdivided into two subgroups for comparison against other tumour classes: those with high lipid content and those without.

Brain Neoplasms↗
PubMedDate not supplied

Age of pubertal onset affects the intensity and duration of pubertal growth peak but not final height.

This paper analyzed the intensity and duration of height growth during puberty in boys and girls in relation to rhythm of maturation. A longitudinal clinical follow-up between ages of 10 and 20 years, was carried out in a sample of 251 children grouped according to age at pubertal onset: boys (genital stage 2) at the ages of 11 (n = 28), 12 (n = 38), 13 (n = 42), and 14 (n = 27); and girls (breast stage 2) at the ages of 10 (n = 37), 11 (n = 47), 12 (n = 19), and 13 (n = 13). Height was measured annually. Testicular volume and genital development were assessed in boys, and breast development was assessed in girls. There were significant differences (P < 0.001) in height at the age of pubertal onset among maturity groups. Late maturers were taller than early maturers (r = 0.49, P < 0.001 for girls; r = 0.38, P < 0.001 for boys). However, final heights did not differ according to age of onset in either sex. In boys, later onset of puberty was associated with a smaller pubertal height gain (r = -0.60, P < 0.001) and a shorter period of pubertal growth (r = -0.61, P < 0.001). Equally in girls, earlier onset of puberty was associated with a greater pubertal height gain (r = -0.68, P < 0.001) and a longer period of pubertal growth (r = -0.59, P < 0.001). In conclusion, age of pubertal onset does not affect final height attained in both sexes, since there is an inverse compensatory phenomenon in both sexes between height at pubertal onset and the intensity and duration of pubertal growth.

Adolescent↗
PubMedDate not supplied

1H NMR spectroscopy of colon tumors and normal mucosal biopsies; elevated taurine levels and reduced polyethyleneglycol absorption in tumors may have diagnostic significance.

Twenty-three pairs of normal mucosa and colonic adenocarcinoma biopsy specimens have been examined in this pilot study by 1H NMR spectroscopy at 9.4 T to determine whether it was possible to find spectral malignancy markers. The 3.2 ppm (trimethylamine-containing compounds)/0.9 ppm (methyl of fatty acids) resonance intensity ratio in water suppressed spectra, proposed by other authors as a malignancy marker, results in our hands, using resonance areas, in partial overlap between tumor and mucosa values, which reduces its diagnostic value. Furthermore, we have found that submucosa contamination could mask the normal mucosa pattern and artifactually decrease the 3.2/0.9 ppm, ratio value by increasing the 0.9 ppm resonance due to the known triglyceride content of normal submucosa. On the other hand, we have observed in the Hahn spin-echo spectra of intact biopsies resonances arising from taurine and exogenous polyethyleneglycol (PEG). Their assignment and quantification has been carried out in perchloric acid extracts of the tissue biopsies. The taurine (3.4 ppm)/creatine (3.0 ppm) area ratio produced an excellent discrimination between normal mucosa and tumour groups while the PEG (3.7 ppm)/creatine (3.0 ppm) area ratio presented a large overlap, although it was clearly higher in the mucosae than in the tumors for paired samples. These two NMR observable parameters are in our hands highly discriminating and are accordingly proposed as malignancy markers in tissue biopsies although their possible utility for in vivo studies remains to be demonstrated.

Adenocarcinoma↗
PubMedDate not supplied

Mycotic aneurysm of the abdominal aorta: CT finding in three patients.

We present three cases of mycotic aneurysms of the abdominal aorta that were initially diagnosed with computed tomography (CT). The accuracy of CT as the first imaging technique in the diagnosis of this condition is reviewed in light of our results and those reported in the literature.

Aged↗
PubMedDate not supplied

Parental factors related to bulimia nervosa.

The purpose of the present study was to examine the relationship between parental factors and bulimia nervosa. Subjects were female undergraduate students (classified as bulimic, subclinical bulimic, or normal) and their parents. Daughters and their parents were administered a questionnaire which assesses attitudes about being overweight, radical dieting, and parental pressure to lose weight. The bulimic group, and in some instances the subclinical group, were significantly different in that they reported perceiving themselves to be overweight, engaging in radical means of weight control, and perceiving more parental pressure to radically diet and exercise. The mothers of bulimic students, and in some instances subclinical bulimic students, were significantly different from the mothers of normal students in restricting their daughters' food intake, encouraging their daughters to diet and exercise in order to lose weight, and perceiving their daughters as being overweight. There were no significant differences among the three groups of fathers. Limitations of these findings were discussed as well as implications for further research.

Adolescent↗
PubMedDate not supplied

Cytomegalovirus infection in simultaneous pancreas-kidney transplantation.

INTRODUCTION: In this open-label multicenter study, 205 simultaneous pancreas-kidney (SPK) transplant recipients between 1998 and 2000 were randomly assigned to tacrolimus or cyclosporine-microemulsion (ME). All patients received concomitant rATG induction therapy, mycophenolate mofetil and short-term corticosteroids. We report the 3-year data related to the occurrence, severity and effect of cytomegalovirus (CMV) infections. The type of CMV prophylaxis and treatment was at the discretion of the investigator. RESULTS: The overall incidence of CMV infection was 34% with no difference in incidence between the tacrolimus and cyclosporine-ME treatment arms. Statistically significant fewer CMV infections occurred among patients who received ganciclovir (22%) than those who did not receive prophylaxis (42%; P = .0075) or were treated with acyclovir (43%; P = .0066). The CMV infection rate according to donor recipient CMV serological status was: D-/R- group 11%, which was lower than the D-/R+ group at 40% (P = .0035), the D+/R+ group at 37% (P = .0024), or the D+/R- group at 52% (P = .00001). Among the last three groups, the infection rate was lower in patients on ganciclovir than those with no prophylaxis or on acyclovir (22% vs 64%; P = .00001). The incidence of acute rejection episodes was higher among patients without ganciclovir prophylaxis. No difference was observed in actuarial patient, kidney, or pancreas survival rates between patients with versus without infection. CONCLUSIONS: Ganciclovir prophylaxis effectively prevented CMV infection in SPK transplant recipients, especially in higher risk groups. An effect of CMV prophylaxis on the incidence of rejection is possible.

Cytomegalovirus Infections↗
PubMedDate not supplied

Evaluation under field conditions of the colourimetric DELI-microtest for the assessment of Plasmodium falciparum drug resistance.

It has been frequently stressed that improved methods are needed to monitor the fast spread of drug-resistant Plasmodium falciparum parasites in endemic areas. We recently developed a colourimetric microtest, double-site enzyme-linked lactate dehydrogenase enzyme immunodetection assay (DELI), to assess drug resistance in vitro. This method, which proved highly effective under laboratory conditions, was evaluated under field conditions in 2 African areas (in Senegal and Burkina Faso) in 1997 and 1998, respectively. The sensitivities of isolates from symptomatic (n = 50) and asymptomatic individuals (n = 26) infected with P. falciparum were assessed in parallel by the new DELI-microtest and the isotopic-microtest. IC50 values of the isolates determined for chloroquine, quinine, amodiaquine and mefloquine were well correlated (r = 0.79, P < 0.001). The proportions of sensitive and resistant isolates determined using the 2 methods were similar. The DELI-microtest proved to be faster to implement than the isotopic-microtest, easier to perform, and did not require sophisticated equipment. Moreover, a larger number of isolates can be tested since parasitaemias as low as 0.005% could be reliably measured with the DELI-microtest. These initial field studies thus support the value of the DELI-microtest for large-scale drug-sensitivity monitoring.

Animals↗