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Biomedical subjects

A Meyer

Publications and source records attributed to A Meyer.

At least 145 records · Page 8Linked to original sources
PubMed2000

Role of transesophageal endosonography-guided fine-needle aspiration in the diagnosis of lung cancer.

STUDY OBJECTIVE: Bronchoscopic methods fail to diagnose lung cancer in up to 30% of patients. We studied the role of transesophageal endosonography (EUS)-guided fine-needle aspiration (FNA; EUS-FNA) in such patients. DESIGN: Prospective study. The final diagnosis was confirmed by cytology, histology, or clinical follow-up. SETTING: University hospital. PATIENTS: Thirty-five patients (30 male and 5 female; mean age, 60.9 years; range, 34 to 88 years) with suspected lung cancer in whom bronchoscopic methods failed. Patients with a known diagnosis, recurrence of lung cancer, or mediastinal metastasis from an extrathoracic primary were excluded. INTERVENTIONS: EUS and guided FNA of mediastinal lymph nodes. RESULTS: The procedure was uneventful, and material was adequate in all. The final diagnosis by EUS-FNA was malignancy in 25 patients (11 adenocarcinoma, 10 small cell, 3 squamous cell, and 1 lymphoma) and benign disease in 9 patients (5 inflammatory, 2 sarcoidosis, and 2 anthracosis). Another patient with a benign result had signet-ring cell carcinoma diagnosed on pleural fluid cytology (probably false-negative in EUS-FNA). The sensitivity, specificity, accuracy, and positive and negative predictive values were 96, 100, 97, 100, and 90%, respectively. There were no complications. Reviewing the EUS morphology, the nodes were predominantly located in levels 7 and 8 of American Thoracic Society mediastinal lymph node mapping (subcarinal and paraesophageal region). In seven patients, the punctured nodes were < 1 cm (four malignant and three benign), which are difficult to sample by other methods. The malignant nodes had a hypoechoic, homogenous echotexture. CONCLUSIONS: EUS-FNA is a safe, reliable, and accurate method to establish the diagnosis of suspected lung cancer when bronchoscopic methods fail, especially in the presence of small nodes.

Adult↗
PubMed2000

Diagnosing sarcoidosis using endosonography-guided fine-needle aspiration.

STUDY OBJECTIVES: The ability to diagnose sarcoidosis cytologically has been reported previously, but the method is rarely used. Endoscopic ultrasonography (EUS) is a sensitive technique for detecting mediastinal lymph nodes, which in addition provides an opportunity to carry out guided fine-needle aspiration (FNA) cytology. We report herein on the use of EUS-FNA in the diagnosis of sarcoidosis. PATIENTS AND METHODS: Nineteen patients with suspected sarcoidosis were investigated using EUS-FNA with a linear echoendoscope and a 22-gauge Hancke-Vilman needle. MEASUREMENTS AND RESULTS: In all 19 patients, EUS revealed enlarged mediastinal lymph nodes (mean size, 2.4 cm), located subcarinally (n = 15), in the aortopulmonary window (n = 12), or in the lower posterior mediastinum (n = 5). The nodes had an isoechoic or hypoechoic appearance, with atypical vessels in five cases. The amount of aspirate obtained using EUS-FNA was adequate in all patients, and contained blood in excess of normal in some, indicating a high degree of vascularity. Cytology demonstrated epithelioid cell granuloma formation, suggesting sarcoidosis. Mycobacterial cultures were negative in all of the patients except one, in whom the final diagnosis was tuberculosis. The specificity and sensitivity of EUS-FNA in the diagnosis of sarcoidosis were 94% and 100%, respectively. CONCLUSIONS: EUS of mediastinal lymph nodes in sarcoidosis reveals certain characteristic features. However, it is not capable of differentiating the lesions from tuberculosis or malignancy. EUS-FNA is a safe and sensitive method of aspirating material for cytology and mycobacterial cultures. We believe it will provide a useful alternative in the diagnosis of sarcoidosis.

Adult↗
PubMed2000

[Indicators for ambulatory quality management in patients with bronchial asthma].

The process of quality assurance and quality improvement in ambulatory care is bound to the development of quality indicators. The performance and outcomes of medical services offered by physicians have to be assessed on the basis of valid, reliable and practicable indicators. The aim of this analysis was to identify relevant process and outcome measures which could be used as quality indicators in ambulatory care of asthmatic patients in Germany. Therefore, the process of routine ambulatory care of asthmatic patients was analyzed and compared to existing management guidelines of national and international expert panels. A set of 51 indicators was derived from this analysis and a systematic review of 96 articles on quality management of asthma care selected after research in MEDLINE 1966-1997. This list of quality indicators should be discussed in quality circles for practicability in ambulatory care settings.

Ambulatory Care↗
PubMed2000

[Choroidal melanoma. An anatomic-clinical case report].

A 78-year-old-male-patient had his left eye affected by a 10 mm thick choroidal malignant melanoma. The size of the tumor did not allowed to keep the eye, and no conservative treatment was used for therapy. Enucleation was performed and histopathological study of the eye showed a mushroom-shaped and mixed-cell choroidal melanoma, devoid of transcleral extension, but harboring intrascleral infiltration. A period of 2 year-follow-up without metastasis was observed since the removal of the tumoral eye.

Aged↗
PubMed2000

[Residual left orbital phlebolith. An anatomic-clinical observation].

A 29-year-old female patient displayed a dense and hard left orbital mass, inferiorly, 3 years after she was treated through a neurosurgical approach for a left orbital varix. The lesion was hyperdense on CT-scan and was removed through a trans-conjunctival approach, with an excellent result. The histological diagnosis was a phlebolith.

Adult↗
PubMed2000

[Optic neuropathy after proton-beam therapy for malignant choroidal melanoma].

Proton-beam irradiation is a conservative therapy commonly used for the treatment of uveal malignant melanomas. Some adverse effects such as optic neuropathy can compromise the visual outcome. We were interested in determining the risk factors for radiation papillopathy. Since there is currently no effective therapy, this is an interesting way to improve prevention of optic neuropathy. Six hundred sixty-two eyes had more than 24 month follow-up after proton-beam irradiation for uveal melanoma. In five hundred twenty-two cases, the clinical examination of the optic nerve head by ophthalmoscopy was possible. One-hundred eleven optic discs were pathologic, whereas 411 remained disease-free. Retrospective study of these two groups allowed to quantify the risk factors for optic neuropathy. The irradiation of more than 2mm of optic nerve at 30 Grays-equivalents appeared to be the major risk factor for optic neuropathy. For a given irradiation dose, the observed pattern of clinical responses was heterogeneous. These results are discussed and compared to the previous published reports. Visual results and life prognosis are also discussed, considering the optic nerve head status. Proton-beam therapy can preserve the optic nerve when the tumor location allows to keep it away from the irradiation-field. Patients must be informed about the risk of optic neuropathy after proton-beam irradiation.

Choroid Neoplasms↗
PubMed2000

[Unusual preseptal location of an orbital cavernous hemangioma in African patient].

Cavernous hemangioma is the most common primary vascular orbital tumor in adults. Generally the benign tumor arises within the muscle cone, revealed by proptosis with choroidal folds, and more rarely develops in other orbital localizations. We report the case of a 42-year-old female African patient who had a cavernous hemangioma in an unusual anterior localization. Clinically, a small superficial tumor was palpated in the right superior nasal orbital angle. After complete surgical excision, the histopathological study established the diagnosis of cavernous hemangioma

Adult↗
PubMed2000

[Orbital dysembryoplastic cyst at the conjunctival wall].

An 18-year-old female patient developed a mass in the superomedial angle of her left orbit. After evaluation, this tumor was surgically removed. A dysembryoplastic cyst lined with conjunctival epithelium was diagnosed by light microscopic examination. Clinical and pathological data are detailed. The characteristics of dysembryoplastic orbital cysts are reviewed.

Adolescent↗
PubMed1999

[Heart transplantation in myocardial sarcoidosis. Studies on the explanted heart].

HISTORY AND CLINICAL FINDINGS: A 40-year-old man with histologically proven sarcoidosis, known for 15 years, which had involved the myocardium was hospitalized because of intractable heart failure (NYHA class IV). An implantation of an intracardiac defibrillator for ventricular arrhythmias (Lown type IVa) had preceded. On physical examination severe dyspnea at rest cough and fever were noted. INVESTIGATIONS: The erythrocyte sedimentation rate (88/104 mm), C-reactive protein (250 mg/l) and white cell count (20/nl) were markedly increased. Serum sodium (113 mmol/l), potassium (3.0 mmol/l) and chloride (64 mmol/l) were markedly reduced, while creatinine (2.5 mg/dl) and urea (82 mg/dl) were elevated due to renal failure. The chest radiogram demonstrated central venous congestion, cardiomegaly and right pericardial infiltration. There were no obvious changes due to sarcoidosis and computed tomography did not indicate pulmonary involvement by sarcoidosis. The echocardiogram revealed severe impairment of left ventricular function with an ejection fraction of ca. 14%. DIAGNOSIS, TREATMENT AND COURSE: Heart failure (NYHA class IV), caused by a dilated cardiomyopathy of sarcoidosis, was accompanied by pneumonia which responded to antibiotics. But the chronic heart failure failed to improve on drug treatment and cardiac transplantation was undertaken. The explanted myocardium was examined histologically, immunologically and virologically. Antibodies were demonstrated against vascular endothelium, sarcolemma and endocardium (IgG and IgA), but not by PCR against cytomegalovirus, enterovirus and adenovirus. The transplantation was without complication and, under azathioprine and methylprednisolone, one rejection had occurred until now. The patient has been working full-time since 2 years in his previous occupation of lorry driver. There has been no evidence of renewed sarcoidosis activity. CONCLUSION: Sarcoidosis may involve the myocardium in up to 25% of cases. Clinically relevant symptoms are even more rare. Sarcoidosis should be included in the differential diagnosis of unexplained serious arrhythmias or cardiomyopathy, particularly in young persons. Cardiac transplantation may have to be contemplated if drug or pacemaker treatment fails to control heart failure.

Adenoviridae↗
PubMed1999

Replicated evolution of trophic specializations in an endemic cichlid fish lineage from Lake Tanganyika.

The current phylogenetic hypothesis for the endemic Lake Tanganyika cichlid fishes of the tribe Eretmodini is based solely on morphology and suggests that more complex trophic morphologies derived only once from a less specialized ancestral condition. A molecular phylogeny of eretmodine cichlids based on partial mitochondrial DNA cytochrome b and control-region sequences was used to reconstruct the evolutionary sequence of trophic adaptations and to test alternative models of morphological divergence. The six mitochondrial lineages found disagree with the current taxonomy and the morphology-based phylogeny. Mitochondrial lineages with similar trophic morphologies are not grouped monophyletically but are typically more closely related to lineages with different trophic phenotypes currently assigned to other genera. Our results indicate multiple independent origins of similar trophic specializations in these cichlids. A pattern of repeated divergent morphological evolution becomes apparent when the phylogeography of the mitochondrial haplotypes is analyzed in the context of the geological and paleoclimatological history of Lake Tanganyika. In more than one instance within Lake Tanganyika, similar morphological divergence of dentitional traits occurred in sympatric species pairs. Possibly, resource-based divergent selective regimes led to resource partitioning and brought about similar trophic morphologies independently and repeatedly.

Animals↗
PubMed1999

Construction of a variability map for eukaryotic large subunit ribosomal RNA.

In this paper, we present a variability map of the eukaryotic large subunit ribosomal RNA, showing the distribution of variable and conserved sites in this molecule. The variability of each site in this map is indicated by means of a colored dot. Construction of the variability map was based on the substitution rate calibration (SRC) method, in which the substitution rate of each nucleotide site is computed by looking at the frequency with which sequence pairs differ at that site as a function of their evolutionary distance. Variability maps constructed by this method provide a much more accurate and objective description of site-to-site variability than visual inspection of sequence alignments.

Animals↗
PubMed1999

Vertebrate genomics: More fishy tales about Hox genes.

Zebrafish Hox genes are arranged in at least seven clusters, rather than the four clusters typical of vertebrates. This suggests that an additional genome duplication occurred on the fish lineage and explains why many gene families are typically about half the size in land vertebrates than they are in fish.

Animals↗
PubMed1999

Attempt to modify the immune response developed against FIV gp120 protein by preliminary FIV DNA injection.

Following inactivated virus vaccination trials, the surface glycoprotein gp120 (SU) of the feline immunodeficiency virus (FIV) was considered as one of the determinants for protection. However, several vaccination trials using recombinant Env protein or some Env-derived peptides failed to induce protection. To study the influence of the environment in which the surface protein (SU) is injected. we analyzed the impact of a nucleocapsid (NC) DNA immunization on the presentation of the recSU protein to the immune system. Cats were vaccinated either with the recSU protein alone or with NC DNA followed by the recSU protein. Two routes of nucleocapsid DNA vaccination were tested: intramuscular and mucosal injections. Cats immunized with the recSU protein showed a facilitation of infection, since they presented the earliest and the highest humoral response correlating with the highest proviral load. They also showed an acceleration of the appearance of IL4 mRNA signal. Preliminary injection of the DNA coding for NC protein, regardless the route of inoculation, seemed to inhibit the facilitation induced by vaccination with the recSU protein alone. The previously nucleocapsid DNA immunized cats had infectious status similar to those of the control cats, but with lower proviral load and less developed anti-FIV humoral response. Cat No. 2, belonging to the group vaccinated with NC protein by the mucosal route, had a protected-like status which did not correlate with the humoral response. This cat was the only one to have a persisting IFN mRNA signal after challenge specific for the p10 nucleocapsid and recSU proteins. However, no NC specific cytotoxic cells were observed throughout the experiment in this cat. The role of nucleocapsid DNA vaccination is still unknown nevertheless we did demonstrate that the facilitation observed in vaccination trial with recombinant proteins could be modified and that recombinant proteins could be a component of an effective vaccine.

Animals↗
PubMed1999

Establishment of experimental conditions for the rapid detection of mutations in the von Hippel-Lindau gene by parallel temperature gradient gel electrophoresis.

Renal cell carcinoma (RCC) is the most common adult kidney neoplasm and is present in approximately 3% of all adult malignancies. Mutations of the von Hippel-Lindau (VHL) gene had been found in 55-70% of sporadic RCC and appear to be a critical event in the pathogenesis of clear-cell RCC. Several screening procedures for the detection of mutations in the VHL gene such as single-strand conformation polymorphism analysis, Southern blot and polymerase chain reaction (PCR)-employing methods had been used. Recently, the perpendicular temperature gradient gel electrophoresis (TGGE) was successfully applied to detect genetic alterations in the VHL gene. Here, the experimental conditions for parallel TGGE were established. The results on eleven samples with mutations in different exons demonstrate that parallel TGGE can be used as a simple and rapid method to detect mutations in the VHL gene. Several samples can be run at the same time, making parallel TGGE ideal for the screening of a large number of samples.

Adult↗
PubMed1999

Homology and homoplasy: the retention of genetic programmes.

Homology describes the inevitable evolutionary phenomenon that the similarity of structures among different organisms is due to the commonality of their descent. This continuity of information is maintained in evolutionary lineages in terms of genes and developmental mechanisms and will retain 'sameness' and retard, funnel and direct evolutionary diversification. Analogous 'sameness' is said to be due to independent, convergent evolution, and also involves similarity of function; the latter is not a necessary condition for structures to be identified as homologous. Here, I suggest that the biological basis for these seemingly disparate kinds of 'sameness' in evolution may in some, or even most, instances not be all that different and may be based on the same principle-the long evolutionary retention of genes, gene interactions and developmental mechanisms. Evolution might recycle and re-recruit similar mechanisms repeatedly during its course, and it often makes do with what is already available to it rather than to newly evolve or reinvent many gene interactions and developmental mechanisms repeatedly. Apparently there is no, or only a negligible, 'genomic cost' or even a selective advantage to maintaining genes and developmental mechanisms for long evolutionary periods of time, even if they are not continuously used in all members along an evolutionary line. Therefore, the biological basis of both homologous traits (those that are evolutionarily always expressed) and homoplasious traits (those that are not always 'on', but are 're-awakened' during evolution) might not be so different, and the distinction between homology and some forms of homoplasy may be somewhat artificial.

Amphibians↗