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Biomedical subjects

A Kessler

Publications and source records attributed to A Kessler.

At least 19 recordsLinked to original sources
PubMed2002

Remarkable morphological diversity of viruses and virus-like particles in hot terrestrial environments.

Electron microscopic studies of the viruses in two hot springs (85 degrees C, pH 1.5-2.0, and 75-93 degrees C, pH 6.5) in Yellowstone National Park revealed particles with twelve different morphotypes. This diversity encompassed known viruses of hyperthermophilic archaea, filamentous Lipothrixviridae, rod-shaped Rudiviridae, and spindle-shaped Fuselloviridae, and novel morphotypes previously not observed in nature. Two virus types resembled head-and-tail bacteriophages from the families Siphoviridae and Podoviridae, and constituted the first observation of these viruses in a hydrothermal environment. Viral hosts in the acidic spring were members of the hyperthermophilic archaeal genus Acidianus.

Archaea↗
PubMed2002

[Hearing disorders in children with Down's syndrome].

Among 4947 children in an outpatients unit for hearing disorders 102 children with Down's syndrome were seen and checked for hearing disorders. 57 had hearing deficiencies, 50 (88 %) conductive hearing loss, 4 (7 %) combined and 3 (5 %) a sensory neural hearing loss. Compared to other publications the number of very young children was very high. 32 patients under two years of age had a hearing disorder. The results underline the necessity of early diagnosis and follow up also in children with normal reactions during the first presentation. Early diagnosis enables early treatment, conservative, surgical or fitting with hearing aids, especially important in the rehabilitation of these children. Hearing aids may be given temporarily imploring communication during the development of the child.

Child↗
PubMed2002

Serum leptin level in women with idiopathic intracranial hypertension.

Leptin is a protein secreted by adipose cells which influences regulation of energy balance and body weight. Idiopathic intracranial hypertension (IIH) is recognised as a neurological disorder mainly affecting obese females. The aim of this study was to evaluate the association between IIH and serum leptin level in 15 obese patients and compare the results with those for 16 obese and 15 non-obese women. A significantly higher serum leptin level was found in patients with IIH than in controls (p<0.0001), and this did not correlate with body mass index (BMI). Serum leptin levels were significantly associated with BMI in both control groups (p<0.0006). Additional factors must therefore be involved in the phenomenon of serum leptin increase beyond weight gain. The cause can only be hypothesised, but it seems that the origin is central, probably hypothalamic.

Adipose Tissue↗
PubMed2001

Defensive function of herbivore-induced plant volatile emissions in nature.

Herbivore attack is known to increase the emission of volatiles, which attract predators to herbivore-damaged plants in the laboratory and agricultural systems. We quantified volatile emissions from Nicotiana attenuata plants growing in natural populations during attack by three species of leaf-feeding herbivores and mimicked the release of five commonly emitted volatiles individually. Three compounds (cis-3-hexen-1-ol, linalool, and cis-alpha-bergamotene) increased egg predation rates by a generalist predator; linalool and the complete blend decreased lepidopteran oviposition rates. As a consequence, a plant could reduce the number of herbivores by more than 90% by releasing volatiles. These results confirm that indirect defenses can operate in nature.

Acyclic Monoterpenes↗
PubMed2001

Merging molecular and ecological approaches in plant-insect interactions.

The singer-song-writer Paul Simon sang about the '50 ways to leave your lover'; plants have at least as many ways of coping with their insect herbivores. Recent research has elucidated the mechanisms of direct and indirect plant defenses, and has provided the first proof of a protective function for indirect defenses in nature. Insect attack elicits a large transcriptional reorganization that differs from that elicited by mechanical wounding. Elicitors in herbivore oral secretions can account for herbivore-specific responses. Patterns of transcriptional changes point to the existence of central herbivore-activated regulators of metabolism.

Adaptation, Physiological↗
PubMed2001

Renal multigated spectral Doppler imaging before and after captopril challenge.

RATIONALE AND OBJECTIVES: A new method of measurement, simultaneous multigated spectral Doppler imaging (MSDI), was used to quantify the hemodynamic changes in kidneys after administration of captopril. METHODS: Forty kidneys in 22 hypertensive patients were included in the study. All underwent MSDI and scintigraphy before and after administration of captopril. RESULTS: With scintigraphy used as the gold standard for diagnosing renal artery stenosis (RAS), three kidneys were found to be positive for RAS. Multigated spectral Doppler imaging detected a decrease in the resistive index after administration of captopril in all patients with RAS and correctly excluded RAS in one patient who was diagnosed as having RAS on scintigraphy. The resistive index was increased after captopril administration in normally functioning kidneys and was unchanged in kidneys with impaired function. CONCLUSIONS: With further supportive evidence, MSDI may prove to be a powerful tool for the acquisition of resistive index information and may increase the value of the resistive index as a physiological hemodynamic parameter in the evaluation of normal and abnormal conditions.

Adolescent↗
PubMed2001

Diversification of cardiac insulin signaling involves the p85 alpha/beta subunits of phosphatidylinositol 3-kinase.

Ventricular cardiomyocytes and cardiac tissue of lean and genetically obese (fa/fa) Zucker rats were used 1) to study the role of the p85 regulatory subunit isoforms p85 alpha and p85 beta for insulin signaling through the phosphatidylinositol (PI) 3-kinase pathway, and 2) to elucidate the implications of these mechanisms for cardiac insulin resistance. Western blot analysis of cardiomyocyte lysates revealed expression of p85 alpha and p85 beta but no detectable amounts of the splice variants of p85 alpha. Essentially no p85 alpha subunit of PI 3-kinase was found to be associated with insulin receptor substrate (IRS)-1 or IRS-2 in basal and insulin-stimulated (5 min) cardiomyocytes. Instead, insulin produced a twofold increase in p85 beta associated with IRS-1, leading to a three- to fourfold increase in p85 beta-associated PI 3-kinase activity. This response was significantly reduced in obese animals. Comparable results were obtained in the intact heart after in vivo stimulation. In GLUT-4-containing vesicles, an increased abundance (3.7 +/- 0.7-fold over basal) of p85 alpha was observed after insulin stimulation of lean animals, with no significant effect in the obese group. No p85 beta could be detected in GLUT-4-containing vesicles. Recruitment of the p110 catalytic subunit of PI 3-kinase and a twofold increase in enzyme activity in GLUT-4-containing vesicles by insulin was observed only in lean rats. We conclude that, in the heart, p85 alpha recruits PI 3-kinase activity to GLUT-4 vesicles, whereas p85 beta represents the main regulator of IRS-1- and IRS-2-mediated PI 3-kinase activation. Furthermore, multiple defects of PI 3-kinase activation, involving both the p85 alpha and the p85 beta adaptor subunits, may contribute to cardiac insulin resistance.

Animals↗
PubMed2001

Thyroglossal duct cyst: is thyroid scanning necessary in the preoperative evaluation?

BACKGROUND: Evaluation of thyroglossal duct cysts before surgical excision traditionally includes hormonal evaluation, ultrasound of the neck, and thyroid scanning. OBJECTIVE: To evaluate the need for thyroid scanning in cases of thyroglossal duct cysts scheduled for operation. METHODS: A retrospective chart review of 100 cases of thyroglossal duct cyst between 1988 and 1995 was carried out. RESULTS: No cases of ectopic thyroid were detected. CONCLUSION: Our goal was to document the presence of normal thyroid tissue by non-invasive tools such as ultrasound, rather than to rule out the existence of ectopic thyroid tissue by radionuclide scanning. Radionuclide scanning is justified in cases of lingual thyroid and where a normally located thyroid gland cannot be detected.

Adolescent↗
PubMed2000

Molecular mechanisms of contraction-regulated cardiac glucose transport.

Insulin and contraction are the most important regulators of glucose utilization in cardiac muscle. In contrast with insulin, the intracellular signalling elements of contraction have remained unexplored. In the present studies, adult rat ventricular cardiomyocytes were electrically stimulated to perform rhythmic contractions to permit the determination of potential sites of convergence of contraction and insulin signalling to glucose transport. The participation of phosphoinositide 3-kinase (PI-3K) in Ca(2+)- and contraction-stimulated 3-O-methylglucose transport was suggested by the great sensitivity of this process towards the PI-3K inhibitors wortmannin and LY294002 and by the presence of PI-3K activity in anti-phosphotyrosine immunoprecipitates from contracted cells. Initial signalling events of insulin action, including receptor kinase activation, the tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and IRS-2 and the recruitment of PI-3K to IRS-1 and IRS-2, were found not to be involved in contraction-mediated signalling. However, immunoprecipitation of p85alpha revealed a markedly enhanced tyrosine phosphorylation of an unknown co-precipitated 200 kDa protein in response to both stimuli. It is concluded that contraction-regulated cardiac glucose transport involves the activation of PI-3K in response to upstream signalling pathways different from that of insulin.

Androstadienes↗
PubMed2000

[Bilateral acoustic trauma after air bag inflation].

Airbag inflation is associated with a loud noise. This very short noise has a peak amplitude of 170 dB sound pressure level and can make otologic injuries. We report a case of acoustic trauma after airbag inflation. The 24-year-old man has hearing loss both side in the 3000- to 6000-Hz range and in the deep-frequency. The possibility of acoustic trauma from airbag noise are probably much more common and need more attention in the clinic.

Adult↗
PubMed2000

Rab11 is associated with GLUT4-containing vesicles and redistributes in response to insulin.

AIMS/HYPOTHESIS: To identify a GTPase of 24,000 M(r) which we recently found to co-localize with GLUT4 in cardiac muscle. METHODS: A 24,000 M(r)-GTP-binding fraction was purified from pig heart by a three-step chromatographic procedure, followed by two-dimensional electrophoresis and electrospray ionization-mass spectrometry. Subcellular distribution of the GTPase was assessed by western blotting. Co-localization with GLUT4 was assessed by continuous sucrose density gradient fractionation and immunoadsorption of GLUT4-containing vesicles. RESULTS: The Rab11 protein was identified as a major component of the GTP-binding fraction and its expression in rat cardiac muscle was confirmed. In vivo insulin treatment resulted in the recruitment of Rab11 from the microsomal fraction to the plasma membrane. Subcellular fractionation indicated two immunoreactive GLUT4 pools. Most of the intracellular pool of Rab11 overlapped with the high-density GLUT4 pool and most of the transferrin receptor pool. The Rab11 protein also co-sedimented with the low-density, non-endosomal GLUT4 pool and substantially increased in this fraction after insulin treatment. It was specifically present in GLUT4-containing vesicles and insulin increased its abundance in these vesicles 2.2-fold relative to the amount of GLUT4. These vesicles also containend Rab4 and Akt-2, the latter being only associated after insulin stimulation. Insulin was unable to alter the cellular localization of Rab11 in insulin-resistant obese Zucker rats. CONCLUSION/INTERPRETATION: These results support the hypothesis that at least two GTPases of the Rab family participate in GLUT4-vesicle trafficking. We suggest that Rab11 is involved in the endosomal recycling, sorting and exocytotic movement of the glucose transporter.

Animals↗
PubMed2000

Non-neoplastic intratesticular lesions mimicking tumour on ultrasound.

It has recently been emphasized that the incidence of benign testicular lesions is much higher than previously suspected. Sonography is reported to have a high sensitivity but poor specificity in the evaluation of intratesticular abnormalities. This report reviews the common and unusual lesions that can mimic testicular tumour on ultrasound, and discusses the clinical and sonographic features that may help to narrow the differential diagnosis and guide management.

Diagnosis, Differential↗
PubMed2000

Quantitative estimation of attenuation in ultrasound video images: correlation with histology in diffuse liver disease.

RATIONALE AND OBJECTIVES: To determine the relationship between the attenuation of backscatter intensity in B-scan images of the liver and diffuse liver disease in order to assess the usefulness of this method in providing quantitative objective characterization of diffuse liver diseases in general and in fatty liver in particular. METHODS: Twenty-four healthy volunteers and 28 patients with elevated liver enzyme levels who underwent liver biopsy were included in this study. An automatic far-field slope (FFS) algorithm that estimates the decrease in amplitude of the backscattered echo as a function of beam depth was implemented on the noncompensated image that was acquired on a commercial phased-array ultrasound system fitted to a custom-built interface card. The images were processed at a work-station. All scans were acquired repeatedly, read, and graded blindly by experienced ultrasound radiologists. Histology obtained via needle biopsy was reviewed without knowledge of the ultrasound findings. RESULTS: Analysis of the FFS data for fatty infiltration in all patient groups yielded a sensitivity of 67%, a specificity of 77%, a positive predictive value (PPV) of 77%, negative predictive value (NPV) of 67%, and an accuracy of 71%. The mean score of the ultrasound reviewers showed a sensitivity of 82%, a specificity of 66%, a PPV% of 68%, an NPV of 81%, and an accuracy of 72%. Normal FFS values (false-negative) were found in five patients with proved fatty infiltration. All of these patients had coexistent moderate to severe hepatic inflammation. However, FFS data in patients with uncomplicated (pure) fatty infiltration revealed a sensitivity of 100%, a specificity of 80%, a PPV of 89%, an NPV of 100%, and an accuracy of 92%. The best ultrasound score yielded a sensitivity of 100%, a specificity of 60%, a PPV of 80%, an NPV of 100%, and an accuracy of 85% in the same patients. CONCLUSIONS: The data demonstrate an excellent sensitivity (100%) of the FFS values in patients with uncomplicated fatty infiltration. This was also the only group of patients in whom the FFS score was superior to the radiologists' best score. The FFS method can be used as a tool to follow up the response to a clinical or research treatment and to obtain standardization of pattern interpretation independently of the individual reader.

Adolescent↗
PubMed2000

Varicocele and the testicular-renal venous route: hemodynamic Doppler sonographic investigation.

The aim of this study was to quantify the anatomic and hemodynamic components of the testicular venous drainage for the purpose of understanding their mechanisms of interacting in producing mutual effects, such as "nutcracker" phenomenon, reflux, and varicoceles. Seventy-five male subjects were studied at rest and during Valsalva maneuver. Aortomesenteric distance and angle, flow velocity in different segments of the renal veins, testicular vein diameter, and flow inversion were evaluated using standard ultrasound equipment with spectral and color Doppler capabilities. The velocity of flow in the proximal segment of the left renal vein (17.5 cm/s) was found to be significantly lower than that in both the distal left renal vein (121 cm/s) and the right renal vein (37 cm/s). The flow velocity in the proximal left renal vein decreased with decrease in the aortomesenteric distance and angle. Testicular vein diameters greater than 3 mm were statistically associated with decreased superior mesenteric artery angle. A significant association also was found between the left testicular vein diameter (in Valsalva maneuver) and inversion of flow. The decrease in flow velocity in the left renal vein proximal to the bifurcation of the superior mesenteric artery from the aorta supports the "nutcracker" theory. An association was found between the decrease of superior mesenteric artery angle and the increase in testicular vein diameter. Another association exists between the presence of reflux during Valsalva maneuver and increased testicular vein diameter. These finding were significant only for testicular vein diameter values greater than 3 mm.

Adolescent↗
PubMed2000

Nasal obstruction in the adult: is CT scan of the sinuses necessary?

OBJECTIVE: To determine whether CT (computerized tomography) scan of the paranasal sinuses is essential in the diagnosis and medical/surgical management of nasal obstruction. DESIGN: One hundred thirteen adult patients with nasal obstruction but without signs of sinusitis who underwent CT examination prior to surgery, were included in the study. RESULTS: Fifty seven percent of the CT scans revealed a variety of abnormal findings. Of the patients with an abnormal CT scan, surgical planning had to be altered in 16 patients due to significant abnormalities found on the CT scans. CONCLUSIONS: We conclude that CT scan of the nose and paranasal sinuses is an effective presurgical planning tool in patients with nasal obstruction.

Adolescent↗
PubMed1999

The role of ultrasound in the diagnosis of stitch granulomas following paediatric herniotomy.

OBJECTIVE: To study the role of US in the diagnosis of stitch granulomas following paediatric herniotomy. MATERIALS AND METHODS: A retrospective 10-year study of herniotomies performed by a paediatric surgical service. RESULTS: Twenty children developed stitch granulomas following herniotomy. In all cases, silk sutures had been used in the repair. Masses appeared 1-10 years following surgery and were demonstrated by preoperative US in 17 patients, by CT alone in 1 patient and by both CT and US in 2 patients. CONCLUSIONS: US is an accurate and cost-effective method for evaluating stitch granulomas following herniotomy in children. The procedure is also valuable in marking the position of these foreign bodies prior to removal.

Child, Preschool↗