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Biomedical subjects

M Hauser

Publications and source records attributed to M Hauser.

At least 55 records · Page 3Linked to original sources
PubMed2000

Genome-wide scan for adult onset primary open angle glaucoma.

Adult onset primary open angle glaucoma is a leading cause of blindness throughout the world. The disease results in an apoptotic death of retinal ganglion cells that is usually associated with an elevation of intraocular pressure. Familial aggregation of the disorder provides evidence for strong genetic influences that are likely to be the result of multiple susceptibility genes. A two-stage genome scan to identify the genomic locations of glaucoma susceptibility genes was performed using an initial pedigree set of 113 affected sibpairs and a second pedigree set of 69 affected sibpairs. Linkage analysis was performed using both model-dependent (lod score) and model-independent affected relative pair and sibpair methods. Twenty-five regions identified by the initial scan were further investigated using the second pedigree set. In the combined data analysis, regions located on chromosomes 2, 6, 9, 11, 14, 17 and 19 continued to produce model-dependent lod scores and/or an MLS >1.0, while five regions (2, 14, 17p, 17q and 19) produced an MLS >2. 0. Multipoint analysis using ASPEX also showed significant results on chromosomes 2, 14, 17p, 17q and 19. These results are an important step towards the identification of genes responsible for the genetic susceptibility to this blinding condition.

Age of Onset↗
PubMed2000

Enkephalins are transported by a novel eukaryotic peptide uptake system.

We have identified an oligopeptide transporter in the yeast Saccharomyces cerevisiae which mediates the uptake of tetra- and pentapeptides, including the endogenous opioids leucine enkephalin (Tyr-Gly-Gly-Phe-Leu) and methionine enkephalin (Tyr-Gly-Gly-Phe-Met). The transporter is encoded by the gene OPT1. Yeast expressing OPT1 can utilize enkephalins to satisfy amino acid auxotrophic requirements for growth. The transport of radiolabeled leucine enkephalin exhibits saturable kinetics, with a K(m) of 310 microM. Transport activity is optimum at acidic pH and sensitive to reagents which uncouple oxidative phosphorylation, suggesting an energy dependence on the proton gradient. Growth, transport, and chromatographic data indicate that leucine enkephalin is not hydrolyzed in the extracellular medium and as such is translocated intact across the cell membrane. The system is specific for tetra- and pentapeptides and can be inhibited by the opioid receptor antagonists naloxone and naltrexone. To date, this is the first example of a eukaryotic transport system which can use enkephalins as a substrate, opening the possibility that a homologue exists in higher eukaryotes.

Animals↗
PubMed2000

Abnormal responses for blood pressure in children and adults with surgically corrected aortic coarctation.

BACKGROUND: Despite successful surgical repair of aortic coarctation, life expectancy is reduced, and up to one-third of patients remain or become hypertensive. So as to characterize the responses for blood pressure, we have studied 55 patients with surgically repaired coarctation. Their mean age was 11.3 +/- 5.97 years. We documented maximal uptake of oxygen, anaerobic threshold, plasma renin activity and blood pressures during a Bruce protocol treadmill test. The velocity across the site of repair as imaged by cross-sectional echocardiography was measured before and after exercise. We measured the changes in heart rate and blood pressure subsequent to an infusion of 1 ug per kg of isoprenalin, monitoring blood pressure over 24 hours in all patients. RESULTS: When compared with 40 healthy age-matched controls, the patients with coarctation had a normal exercise capacity. Resting systolic blood pressures above the 95th percentile were present in 45% of the patients. Exercise-induced hypertension, and an elevation in the average systolic 24 hour blood pressures, were observed, but less frequently than elevated baseline values, suggesting that so-called white-coat" hypertension may be present in this population. Abnormal reactions and elevation of plasma renin activity were related to a history of paradoxical hypertension at the time of surgery. Attenuation of the circadian rhythm for blood pressure was a frequent finding, and may have implications in the development of long-term damage to end-organs. A high correlation was found between mean systolic blood pressure measured by 24 hour monitoring and left ventricular hypertrophy (r=0.65, p<0.05). CONCLUSIONS: Abnormalities in blood pressure occurred independently of significant mechanical obstruction. Despite successful surgical repair, abnormalities in the shape of the aortic arch, reduced sensitivity of baroreceptor reflexes, and neurohumoral factors may all contribute to the development of hypertension.

Adolescent↗
PubMed2000

Juxtaacetabular ganglion as a differential diagnosis in pulsating groin masses.

Ganglion cysts of the hip joint are uncommon synovial-lined fluid-filled juxtaarticular groin lesions. Whereas in the past the correct diagnosis was often made only at surgery there are now valuable imaging methods used for the diagnostic work-up. In experienced hands ultrasonography (US) combined with colour duplex Doppler ultrasonography (CDDS) as a real-time imaging technique easily performed at the patient's bedside is a valid alternative to more expensive or invasive investigations. We report on a patient who presented with a ganglion cyst and in whom first supported by conventional US an aneurysm of the femoral artery was suspected. The diagnosis of a juxtaarticular ganglion was subsequently correctly made at our institution by CDDS and magnetic resonance imaging, respectively, and the cyst was exstirpated successfully. The differential diagnosis of a pulsating groin mass as well as the most useful and specific imaging methods in the diagnostic work-up in this clinical setting are discussed.

Acetabulum↗
PubMed2000

Adjustable laparoscopic gastric banding in patients with morbid obesity: radiographic management, results, and postoperative complications.

PURPOSE: To determine the role of radiographic assessment in patients who underwent an adjustable laparoscopic gastric banding (ALGB) for the treatment of morbid obesity, and to evaluate the frequency and type of postoperative complications. MATERIALS AND METHODS: From September 1995 to March 1998, 98 consecutive patients (18 men, 80 women; mean age, 39 years; age range, 22-62 years) with morbid obesity (mean body weight, 132 kg; mean body mass index, 47.1 kg/m(2)) underwent ALGB. In all patients, fluoroscopy was performed postoperatively to confirm band position and to exclude perforation and at 6-8 weeks later to measure and adjust the stoma between the pouch and stomach for optimal weight loss. All patients underwent another examination 12 months postoperatively, whereas patients with unsatisfactory weight loss or patients suspected of having complications were examined earlier and on several occasions. RESULTS: Port puncture was feasible in all cases, and stomal adjustments could easily be repeated. Absolute (ie, total) weight loss after 1 year ranged from 8.8% to 39.2% (mean, 18.3%). Twenty patients showed unsatisfactory weight loss. No early complications occurred. Late complications occurred in 34 patients and included pouch dilatation (concentric or eccentric with posterior slippage), eccentric band herniation, band penetration, disconnection, axial pouch herniation, and port-site infection. CONCLUSION: ALGB is an effective method in the treatment of morbid obesity. Radiographic assessments are crucial in the management of weight loss and detection of postoperative complications.

Adult↗
PubMed1999

Expression of the 71 kDa dystrophin isoform (Dp71) evaluated by gene targeting.

To investigate the function of the major non-muscle dystrophin isoform, Dp71, we substituted a beta-galactosidase (betagal) reporter gene for Dp71 by homologous recombination in embryonic stem cells. Staining for betagal activity in chimeric mice revealed Dp71 promoter activity in glial cells in the CNS, in neurons of the inner nuclear and inner plexiform layers of the retina, and in the kidney tubules and collecting ducts. Our observations demonstrate that Dp71 is widely expressed in the adult CNS (retina, cerebellum, cerebral cortex, ependyma, and choroid) as well as the adult kidney epithelium and suggest a broad function for Dp71 in differentiated tissues.

Animals↗
PubMed1999

[Pseudomonas pneumonia--an important differential pulmonary infiltration diagnosis in AIDS].

Bacterial pneumonias are the most common pulmonary complication in HIV-infected patients. Up to now, H. influenzae and S. pneumoniae have been described as the most important germs. Within a period of 4 years we diagnosed 15 cases of pneumonia caused by P. aeruginosa. All patients were in HIV stage C3; 3F, 12M; median age 34 (24-54) years; median CD4 count 10 (0-130) microliters. Except for 3 nosocomial pneumonias, all others were community-acquired. Only 3 patients had neutropenia < 1000/microliter; 7 were intravenous drug abusers. Morphologically there were 6 cases of abscess pneumonia, in 3 of which pleural drainage was necessary because of pyopneumothorax. 4 patients showed bilateral infiltrates that could not be differentiated from those of P. carinii pneumonia. Our diagnosis was based on quantitative cultures of broncho-alveolar lavage fluid (9 cases, two of them with concurrent positive blood cultures/positive cultures of the pleural fluid), pleural puncture (one case), sputum in pneumonias responding only to antipseudomonas therapy (3 cases), and autopsy (2 cases). 8 patients died of pseudomonas pneumonia within 1-3 months despite therapy. 7 patients received pseudomonas-specific combination therapy, but all died after median 9 (4-15) months of the underlying illness. In 3 cases recurrent pseudomonas pneumonia could be documented bacteriologically. We conclude that in HIV-infected patients pneumonia caused by P. aeruginosa is a significant and severe pulmonary complication.

AIDS-Related Opportunistic Infections↗
PubMed1999

Complete thromboendarterectomy of the calcified ascending aorta and aortic arch.

BACKGROUND: Arteriosclerotic plaques of the ascending aorta and transverse arch increase the operative risk of cardiac operations and are strong predictors for late cerebrovascular events. METHODS: Twenty-two patients, mean age 68 +/- 6 years (range, 55 to 77 years), with grade IV + V plaques of the ascending aorta and transverse arch underwent coronary artery bypass grafting (n = 21) and aortic valve replacement (n = 8). Cerebrovascular emboli from unknown sources were found preoperatively in 8 patients (36%). All were in sinus rhythm. Complete thromboendarterectomy of the ascending aorta and transverse arch was performed during hypothermic circulatory arrest. After 21 +/- 12 months (range, 4 to 44 months), magnetic resonance imaging and transthoracic echocardiography of endarterectomized vessels was performed. RESULTS: There was one perioperative death (4.5%), one early (4.5%), and one late (4.7%) adverse neurologic event. Follow-up examinations revealed normal diameters of the endarterectomized aorta. CONCLUSIONS: For patients with grade IV + V plaques, thromboendarterectomy of the ascending aorta and transverse arch can be performed with an acceptable surgical risk and a low recurrence rate for cerebrovascular events. Dilatation of the endarterectomized aorta was not observed.

Aged↗
PubMed1999

Video-assisted thoracoscopy in the treatment of pleural empyema: stage-based management and outcome.

OBJECTIVE: Despite modern diagnostic methods and appropriate treatment, pleural empyema remains a serious problem. Our purpose was to assess the feasibility and efficacy of the video-assisted thoracoscopic surgery in the management of nontuberculous fibrinopurulent pleural empyema after chest tube drainage treatment had failed to achieve the proper results. METHODS: We present a prospective selected single institution series including 45 patients with pleural empyema who underwent an operation between March 1993 and December 1996. Mean preoperative length of conservative management was 37 days (range, 8-82 days). All patients were assessed by chest computed tomography and ultrasonography and underwent video-assisted thoracoscopic debridement of the empyema and postoperative irrigation of the pleural cavity. RESULTS: In 37 patients (82%), video-assisted thoracoscopic debridement was successful. In 8 cases, decortication by standard thoracotomy was necessary. There were no complications during video-assisted thoracic operations. The mean duration of chest tube drainage was 7. 1 days (range, 4-140 days). At follow-up (n = 35) with pulmonary function tests, 86% of the patients treated by video-assisted thoracic operation showed normal values; 14% had a moderate obstruction and restriction without impairment of exercise capacity, and no relapse of empyema was observed. CONCLUSIONS: Video-assisted thoracoscopic debridement represents a suitable treatment for fibrinopurulent empyema when chest tube drainage and fibrinolytics have failed to achieve the proper results. In an early organizing phase, indication for video-assisted thoracic operation should be considered in due time to ensure a definitive therapy with a minimally invasive intervention. For pleural empyema in a later organizing phase, full thoracotomy with decortication remains the treatment of choice.

Adolescent↗
PubMed1999

WdChs4p, a homolog of chitin synthase 3 in Saccharomyces cerevisiae, alone cannot support growth of Wangiella (Exophiala) dermatitidis at the temperature of infection.

By using improved transformation methods for Wangiella dermatitidis, and a cloned fragment of its chitin synthase 4 structural gene (WdCHS4) as a marking sequence, the full-length gene was rescued from the genome of this human pathogenic fungus. The encoded chitin synthase product (WdChs4p) showed high homology with Chs3p of Saccharomyces cerevisiae and other class IV chitin synthases, and Northern blotting showed that WdCHS4 was expressed at constitutive levels under all conditions tested. Reduced chitin content, abnormal yeast clumpiness and budding kinetics, and increased melanin secretion resulted from the disruption of WdCHS4 suggesting that WdChs4p influences cell wall structure, cellular reproduction, and melanin deposition, respectively. However, no significant loss of virulence was detected when the wdchs4Delta strain was tested in an acute mouse model. Using a wdchs1Delta wdchs2Delta wdchs3Delta triple mutant of W. dermatitidis, which grew poorly but adequately at 25 degrees C, we assayed WdChs4p activity in the absence of activities contributed by its three other WdChs proteins. Maximal activity required trypsin activation, suggesting a zymogenic nature. The activity also had a pH optimum of 7.5, was most stimulated by Mg(2+), and was more inhibited by polyoxin D than by nikkomycin Z. Although the WdChs4p activity had a broad temperature optimum between 30 to 45 degrees C in vitro, this activity alone did not support the growth of the wdchs1Delta wdchs2Delta wdchs3Delta triple mutant at 37 degrees C, a temperature commensurate with infection.

Amino Acid Sequence↗
PubMed1998

[The thoracic roentgen image: emergency and routine indications in the clinic and general practice].

Even in the era of rapidly emerging cross-sectional imaging techniques (computed tomography, magnetic resonance imaging) the chest radiograph remains the most frequently performed diagnostic imaging procedure and has not lost any importance to other modalities. After technical considerations the value of chest radiography will be discussed based on the most widely applied indications in emergency and routine clinical settings and the link to subsequent imaging modalities will be outlined.

Ambulatory Care↗