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Biomedical subjects

L Simon

Publications and source records attributed to L Simon.

At least 127 records · Page 7Linked to original sources
PubMed1994

[Mechanisms of spinal block formation in Paget disease of bone. Radiographic study based on 14 cases].

Vertebral bridging occurs in approximately 10% of patients with spinal pagetic lesions. Diffuse idiopathic skeletal hyperostosis has been reported in patients with pagetic block vertebras and may facilitate vertebral fusion and extension of pagetic lesions. High prevalences of diffuse idiopathic skeletal hyperostosis have been found in patients with Paget's disease. To determine how pagetic block vertebras develop and to investigate relationships between Paget's disease and diffuse idiopathic skeletal hyperostosis, 244 patients with Paget's disease were studied retrospectively. Diagnostic criteria for diffuse idiopathic skeletal hyperostosis were the presence of flowing ossification along the anterolateral aspect of at least three contiguous vertebral bodies or presence of at least two anterolateral intervertebral bony bridges in the same spinal segment. Eight (33%) of the 244 patients had diffuse idiopathic skeletal hyperostosis. Two-thirds of patients with both conditions were male. There was no statistically significant association between presence of diffuse idiopathic skeletal hyperostosis and spinal involvement by Paget's disease. Fourteen pagetic block vertebras were identified in 11 male patients. Eight of these 11 patients had involvement of the fused vertebras or adjacent vertebras with diffuse idiopathic skeletal hyperostosis. Our findings confirm that diffuse idiopathic skeletal hyperostosis is common in patients with Paget's disease. The statistically significant association between diffuse idiopathic skeletal hyperostosis and pagetic vertebral fusion in the same site suggests that the former condition may be a risk factor for pagetic vertebral bridging.

Adult↗
PubMed1994

Effect of animal age on the uptake of large particulates across the epithelium of the rat small intestine.

A quantitative investigation into the transfer of latex polystyrene particles across the epithelium of the small intestine has been carried out using male weanling, adult and aged Sprague-Dawley rats. Orally administered polystyrene particles, 2 microns in diameter, were transferred from the lumen of the small intestine into the gut associated lymphoid tissues (Peyer's patches). No significant difference in the number of particles transported across the gut epithelium was detected between animals of different age groups. The concentration of particles detected in Peyer's patches excised from the proximal and distal regions of the small intestine of particle-treated animals did not differ significantly, except in aged rats. Particle concentration was significantly higher in Peyer's patch tissue than in adjacent Peyer's patch-free tissues of the small intestine in treated animals of all age groups. The assay method described here may be used for quantitative investigation of the transepithelial transport of large particulates.

Aging↗
PubMed1993

Effect of extradural analgesia on stress responses to abdominal surgery in infants.

We studied 40 children younger than 4 yr having elective abdominal surgery under general anaesthesia supplemented with either systemic opioids or extradural bupivacaine. Venous blood samples were obtained before tracheal intubation to measure baseline concentrations of adrenaline, noradrenaline, glucose, ACTH and cortisol. Additional samples were obtained 45 min after the start of surgery, at the end of surgery, 1 h and 24 h after the end of surgery. Plasma concentrations of bupivacaine were measured also in the extradural group at each sampling time. Both techniques provided acceptable analgesia, but the perioperative increases in adrenaline, glucose and ACTH were significantly greater in the opioid group. Noradrenaline concentrations decreased to less than baseline values in the extradural group and were significantly less than in the opioid group. The perioperative increase in cortisol was similar in the two groups, despite the differences in ACTH responses. Most responses returned to the baseline values within 24 h. Plasma bupivacaine concentrations remained within safe limits during the study, but systemic concentrations increased in some of the patients during postoperative infusion with 0.125% bupivacaine.

Abdomen↗
PubMed1993

Identification of endomycorrhizal fungi colonizing roots by fluorescent single-strand conformation polymorphism-polymerase chain reaction.

A method to identify arbuscular endomycorrhizal fungi based on the amplification of portions of the nuclear gene coding for the small subunit rRNA is presented. By coupling the sensitivity of the polymerase chain reaction and the specificity afforded by taxon-specific primers, a variety of samples can be analyzed, including small amounts of colonized roots. Family-specific primers as well as generic primers are described and can be used to amplify small subunit rRNA fragments from endomycorrhizal fungi by polymerase chain reaction. The amplified products are then subjected to single-strand conformation polymorphism analysis to detect sequence differences. Among the advantages of this approach is the possibility of directly identifying the fungi inside field-collected roots, without having to rely on the fortuitous presence of spores. This technique should have obvious applications in the study of arbuscular endomycorrhizal fungi populations and allow closer examination of their host specificity.

Base Sequence↗
PubMed1993

[Vascular explorations in the diagnosis of algodystrophy].

We applied to a group of 44 patients, clinically affected by algodystrophy, a protocol of vascular explorations (Doppler, capillaroscopy, basal plethysmography, reactive hyperemia test and measurements of the oxygen transcutaneous pressure) in order to analyze their contribution to the detection of such disease, concluding that Doppler, capillaroscopy and plethysmography do not contribute with quantifiable results. On the contrary, the reactive hyperemia test and the measurements of the oxygen transcutaneous pressure showed up as explorations able to quantify the degree of microcirculatory disorder in the algodystrophy and to allow its evolutive follow-up.

Adult↗
PubMed1992

Evolutionary relationships within the fungi: analyses of nuclear small subunit rRNA sequences.

Nucleotide sequences of the small subunit ribosomal RNA (18S) gene were used to investigate evolutionary relationships within the Fungi. The inferred tree topologies are in general agreement with traditional classifications in the following ways: (1) the Chytridiomycota and Zygomycota appear to be basal groups within the Fungi. (2) The Ascomycota and Basidiomycota are a derived monophyletic group. (3) Relationships within the Ascomycota are concordant with traditional orders and divide the hemi- and euascomycetes into distinct lineages. (4) The Basidiomycota is divided between the holobasidiomycetes and phragmobasidiomycetes. Conflicts with traditional classification were limited to weakly supported branches of the tree. Strongly supported relationships were robust to minor changes in alignment, method of analysis, and various weighting schemes. Weighting, either of transversions or by site, did not convincingly improve the status of poorly supported portions of the tree. The rate of variation at particular sites does not appear to be independent of lineage, suggesting that covariation of sites may be an important phenomenon in these genes.

Animals↗
PubMed1992

Terror management and tolerance: does mortality salience always intensify negative reactions to others who threaten one's worldview?

Terror management research has shown that reminding Ss of their mortality leads to intolerance. The present research assessed whether mortality salience would lead to increased intolerance when the value of tolerance is highly accessible. In Study 1, given that liberals value tolerance more than conservatives, it was hypothesized that with mortality salience, dislike of dissimilar others would increase among conservatives but decrease among liberals. Liberal and conservative Ss were induced to think about their own mortality or a neutral topic and then were asked to evaluate 2 target persons, 1 liberal, the other conservative. Ss' evaluations of the targets supported these hypotheses. In Study 2, the value of tolerance was primed for half the Ss and, under mortality-salient or control conditions, Ss evaluated a target person who criticized the United States. Mortality salience did not lead to negative reactions to the critic when the value of tolerance was highly accessible.

Attitude to Death↗
PubMed1992

Why do people need self-esteem? Converging evidence that self-esteem serves an anxiety-buffering function.

Three studies were conducted to assess the proposition that self-esteem serves an anxiety-buffering function. In Study 1, it was hypothesized that raising self-esteem would reduce anxiety in response to vivid images of death. In support of this hypothesis, Ss who received positive personality feedback reported less anxiety in response to a video about death than did neutral feedback Ss. In Studies 2 and 3, it was hypothesized that increasing self-esteem would reduce anxiety among individuals anticipating painful shock. Consistent with this hypothesis, both success and positive personality feedback reduced Ss' physiological arousal in response to subsequent threat of shock. Thus, converging evidence of an anxiety-buffering function of self-esteem was obtained.

Adaptation, Psychological↗
PubMed1992

Rapid quantitation by PCR of endomycorrhizal fungi colonizing roots.

The VANS1/NS21 primer pair is useful for specifically amplifying a 550-bp ribosomal (r) DNA fragment from arbuscular endomycorrhizal fungi, directly from colonized root extracts. A procedure to quantitate these obligatory biotrophs rapidly, based on competitive PCR, was developed by constructing a suitable internal standard to be used with these primers. A 130-bp deletion in the Glomus mossae VANS1/NS21 amplified rDNA fragment was produced by amplifying separately external portions of that fragment, followed by ligation and amplification using the original external primers. When this deleted fragment was added to G. mossae rDNA, amplification using VANS1/NS21 primers yielded the two expected products of 430 bp and 550 bp, respectively, resolved by agarose electrophoresis. This fragment was cloned into the pCL1920 plasmid, a low-copy-number vector (five copies per cell), and mixed with the roots to be analyzed. This provides for a rapid quantitative assay because both steps--extraction of DNA from colonized roots and PCR amplification--are taken into account by the same internal standard. Using this procedure, a sample of colonized leek roots (Allium porum x Glomus vesiculiferum) was shown to contain 5 x 10(4) copies of arbuscular endomycorrhizal fungi rDNA genes per milligram of fresh weight.

Allium↗
PubMed1992

Specific amplification of 18S fungal ribosomal genes from vesicular-arbuscular endomycorrhizal fungi colonizing roots.

The first DNA sequences obtained from arbuscular endomycorrhizal fungi are reported. They were obtained by directly sequencing overlapping amplified fragments of the nuclear genes coding for the small subunit rRNA. These sequences were used to develop a polymerase chain reaction primer (VANS1) that enables the specific amplification of a portion of the vesicular-arbuscular endomycorrhizal fungus small subunit rRNA directly from a mixture of plant and fungal tissues. The specificity of this primer for arbuscular endomycorrhizal fungi was demonstrated by testing it on a number of organisms and by sequencing the fragment amplified from colonized leek (Allium porum) roots. This approach, coupled with other molecular techniques, will facilitate rapid detection, identification, and possibly quantitation of arbuscular endomycorrhizal fungi.

Allium↗
PubMed1992

Esophageal mucosal protection--why do we need a special approach?

The epidemiology and natural history of reflux induced peptic esophageal diseases remain incompletely understood. That is why it is easy to explain that the traditional therapeutic efforts were mostly restricted to the use of acid-reducing or neutralizing drogs. The author tries to survey--mainly on theoretical bases--a new approach of the maintenance treatment of peptic esophagitis and consequential columnar metaplasia. The mechanism of the esophageal antireflux barrier is composed by the (a) lower esophageal sphincter tone, (b) upper esophageal sphincter tone, (c) esophageal acid clearance and (d) esophageal epithelial resistance. The data of a 100-patient-group of gastroesophageal reflux disease cases were retrospectively evaluated principally considering the efficacy of antisecretory treatment relating to the accompanying diseases, recurrence of symptoms and prevention the development of Barrett's columnar lined esophagus and Barrett's ulceration. The decrease of exposure by damaging factors is an essential criterion of antisecretory therapy, having several disadvantages. Based only to logically well established arguments the author believes that gastroesophageal reflux disease and consecutive conditions might be an ideal model for studying and introducing esophageal cyto (-mucosal, -tissue) protection, considering that in the esophagus--in contradiction to the stomach--the cell and tissue injury, induced by several pathogenic agents, does not develop rapidly, and when the organ damage develops gradually, interventions may be possible to protect esophageal cell and the mucosa directly.

Barrett Esophagus↗
PubMed1992

[Severe hypocalcemia complicating outbreaks of renal failure in 2 uremic patients].

Hypocalcemia has many causes of which several often occur in combination in intensive care unit patients. Two cases (a 78-year-old male and a 63-year-old female) of severe hypocalcemia (corrected serum calcium 1.2 mmol/l in both cases) in patients hospitalized for acute decompensation of chronic renal failure are reported herein. Both subjects had a history of chronic hypocalcemia due to vitamin-calcium deficiencies and chronic renal failure. The lack of adverse clinical consequences of the low serum calcium levels can be explained by the fact that both patients also had severe metabolic acidosis, a disorder which increased the ionized fraction of total serum calcium. Serum calcium returned to normal slowly and gradually despite parenteral administration of large amounts of calcium and vitamin D or vitamin D derivatives.

Aged↗
PubMed1991

[Lumbar disk herniation with no surgical treatment. Clinical and x-ray computed tomographic follow-up study].

The authors have studied the clinical and computed tomographic (CT) follow-up of 50 patients with nerve root symptoms and herniated nucleus pulposus (HNP) who received only a conservative medical treatment. The clinical follow-up showed that after 23 months 38 patients (76 percent) did not require surgery and 63 percent of these had good or very good results. Follow-up CT scans, performed in 20 patients, found spontaneous disappearance of NP in 10 cases and partial regression in 3 cases. Several mechanisms may explain this regression, including fragmentation and sequestration of the disc fragment, dehydration and shrinkage of the HNP and its reintegration into the annulus. On the other hand, HNP persisted in some patients who had become asymptomatic, and it was also found in an asymptomatic control subject. These data demonstrate that clinical and CT findings may be dissociated. Not all CT scan-documented HNPs require interventional therapy. Except in case of emergency, surgical treatment should be considered only after failure of conservative medical treatment and whenever clinical and CT data are concordant. CT and other imaging procedures, such as myelography and nuclear magnetic resonance, should only be used preoperatively in patients with appropriate clinical findings.

Adult↗