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Biomedical subjects

J Maurer

Publications and source records attributed to J Maurer.

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

Exercise hemodynamic findings in patients with exertional dyspnea.

To determine whether upright bicycle exercise could provide useful information about disabling exertional dyspnea in the absence of severe abnormalities (as shown by traditional testing methods), we evaluated 13 such patients. There were 3 men and 10 women with a mean age of 49+/-15 (SD) years. We used pulmonary artery catheterization at rest and during upright bicycle exercise to evaluate these patients. All patients had normal left ventricular function except for 1, who had an ejection fraction of 45%. The mean duration to peak exercise was 9+/-6 minutes. Normal systolic pulmonary artery pressure was defined as 25+/-5 mmHg. Four patients had normal systolic pulmonary pressure, and 9 exhibited pulmonary hypertension with exercise. In those 9, the mean mixed pulmonary venous oxygen saturation at rest was 61%+/-9% and fell to 32%+/-9% at peak exercise. Six of the 9 patients also had some degree of resting pulmonary hypertension that worsened with exercise: their mean pulmonary artery systolic pressure at rest was 47+/-14 mmHg and rose to 75+/-25 mmHg at peak exertion (P = 0.01). The other 3 patients showed no pulmonary hypertension at rest; their mean pulmonary artery systolic pressure was 27+/-6 mmHg. However, this level rose to 53+/-4 mmHg at peak exertion (P = 0.04). In this pilot study of patients with dyspnea, 9 of 13 (69%) displayed marked pulmonary hypertension with exercise. The resting hemodynamic levels were normal in 3 (33%) of those with exercise pulmonary hypertension. We conclude that hemodynamic data from bicycle exercise tests can provide additional information regarding the mechanisms of exertional dyspnea.

Catheterization, Swan-Ganz↗
PubMed1999

Identification of a new Escherichia coli She haemolysin homolog in avian E. coli.

Haemolysin is one type of virulence factor that assists in the pathogenesis of Escherichia coli. Currently, hemolytic activity in E. coli has been attributed to haemolysin genes found in either uropathogenic or enterohemorrhagic E. coli. Both haemolysins are classified as RTX toxins because they both have repeats in toxin domains and share similar operon organization, sequence homology, and mechanisms of action. Haemolytic avian E. coli isolates, however, lack either E. coli haemolysin gene. To investigate the avian E. coli haemolysin, a genomic library was made from an avian pathogenic E. coli. A haemolytic clone that was isolated was shown to contain homology with sheA, an E. coli K- 12 gene which causes haemolysis when present in high copy number. The cloned haemolysin gene, hlyE, lacked the conserved amino acid sequence and accessory genes common to all RTX toxins. DNA hybridizations and polymerase chain reaction amplifications showed that the nucleotide sequences homologous to hlyE were not present in a collection of three O157: H7 E. coli, five haemolytic canine uropathogenic E. coli, one haemolytic O26 E. coli, and three haemolytic avian pathogenic E. coli. Thus we have identified a new E. coli haemolysin distinct from the RTX haemolysins and have shown that some avian pathogenic E. coli possess a haemolysin with no apparent homology to hlyE or RTX haemolysins.

Amino Acid Sequence↗
PubMed1999

Optic nerve decompression in trauma and tumor patients.

Optic nerve decompression is a procedure that is now receiving increasing clinical attention. However, there are currently no standardized treatment protocols in the therapy of traumatic or pressure insults to the nerve. The present retrospective study was designed to report our experience with microscopic endonasal transethmoid-sphenoid optic nerve decompression in 24 unilateral trauma cases and 11 unilateral skull base tumor patients. In general preoperative visual acuities in the trauma patients were worse than in the tumor patients. Following surgery, 9 of 11 tumor patients (82%) had at least some improvement of their vision, including 5 complete recoveries. In the group with traumatic visual impairment, 16 of the patients had no light perception preoperatively. Postoperatively, 13 patients (54%) had at least some improvement, with 4 patients regaining normal or near normal vision. Compared to other techniques and approaches, our technique is a minimally invasive procedure for optic nerve decompression, reducing unnecessary operative trauma to nasal structures, skin incisions or even craniotomy and frontal lobe retraction.

Adult↗
PubMed1999

[Experiences with using the Kozlov trocar for trans-facial removal of maxillary sinus pathology].

BACKGROUND: Pathologies of the maxillary sinus can be reached through a transfacial approach. METHODS AND PATIENTS: Therefore a new trocar designed by Kozlov was used to remove pathologic changes in 39 patients using a transcanin fossa puncture approach. A total of 52 procedures were performed and the long-term sequelae were evaluated over a period at least 12 months. RESULTS: This new trocar allowed in all cases for removal of pathologies within the maxillary sinus with various instruments and even powered instruments under microscopic control. Hypesthesia and numbness of the lip and individual teeth persisted after 11 of 52 procedures without major discomfort for the patient. CONCLUSION: This new instrument has proved to be a useful tool to perform limited sinus procedures under local anaesthesia or as an adjunct of endonasal surgery under general anaesthesia in our hands.

Adolescent↗
PubMed1999

[Duplex ultrasonography-controlled Nd:Yag laser therapy of vascular malformations].

AIM: Vascular malformations can be studied in detail by colour Doppler sonography. These lesions are best treated by Nd:YAG laser therapy. The aim of the study was to improve the quality of therapy by the use of colour Doppler sonography guided Nd-YAG laser application. PATIENTS AND METHOD: 17 vascular malformations/haemangiomas in 16 patients were treated by colour Doppler sonography guided Nd:YAG laser therapy. 5 children were less than one year of age, 4 children were between one and five years of age, the other patients were adults (age 22-57 years). The size of the vascular malformations (largest diameter) were 1.5-3 cm (8 cases), all others were larger than 3 cm. RESULTS: When using laser therapy in combination with colour Doppler sonography it is possible to adjust the treatment variables (dose, duration and energy of the laser pulse as well as the precise intralesional positioning) individually. As a result more than 80% of cases can be treated successfully during a single session. Larger lesions may be divided into functional units which can be treated subsequently. CONCLUSION: Through colour Doppler sonography it is possible to monitor the effects of laser treatment in vascular malformations. The development of smaller ultrasound probes has facilitated the application of laser therapy guided by Doppler sonography in the region of the head and neck. Colour Doppler sonography guided laser therapy increases efficiency and selectivity of the laser treatment. Early interventions prevent growth of the lesions and reduce long-term disfigurement particularly in children.

Adult↗
PubMed1999

[Diagnostic procedure in primary ciliary dyskinesia].

BACKGROUND: Primary ciliary dyskinesia (PCD) is usually diagnosed by ultrastructural investigations of nasal or bronchial mucosa. Less invasive techniques for quick and cost-effective diagnosis of PCD should be evaluated. METHODS: In 32 patients with suspected PCD, saccharin transport time, ciliary beating of nasal respiratory epithelium, and ultrastructure of nasal mucosa biopsies were investigated. RESULTS: In 13 patients, PCD was excluded by a normal saccharin transport time (< 20 min). In 19 patients, respiratory cells were obtained by nasal brushing. Frequency, coordination, and amplitude of ciliary beating were examined using interference contrast microscopy and scored. PCD was excluded in 10 of 19 patients, who revealed normal ciliary activity. In the remaining 9 patients, nasal mucosa specimens for ultrastructural investigation were obtained. Ultrastructural alterations indicating PCD were found 4 of 9 specimens, in 2 specimens no cilia were found and in 3 specimens alterations indicating secondary inflammatory alterations were found. CONCLUSIONS: PCD may be efficiently excluded in several cases using cost-effective diagnostic techniques. The definite diagnosis in the remaining cases requires ultrastructural investigations which should be performed in specialized centers. In the present study, PCD in a carefully preselected group had a surprisingly high prevalence.

Adolescent↗
PubMed1999

[Orientational evaluation of otolith function by eye counter-rolling in patients with various kinds of vertigo].

BACKGROUND: Measurement of ocular counterrolling (OCR) is well known as a simple method to evaluate the peripheral vestibular organ, especially the otolith organ. But it has rarely been used because of the difficulty in differentiating between pathologically reduced OCR and the wide physiological variation of this parameter. PATIENTS: In this study, the OCR of 55 patients with unclarified vertigo (n = 20), vestibular neuronitis (n = 15), Menière's disease (n = 10), and benign paroxysmal positional nystagmus (n = 10) were evaluated and compared to a control group (n = 30) with the intention of diagnosing peripheral vestibular dysfunction and establishing a differential diagnosis. The test sequence was carried out with Vesta goggles by Panares and included head tilts of 5 degrees, 15 degrees, and 30 degrees to the left and right. RESULTS: The results show a significantly reduced OCR in patients suffering from peripheral vestibular disorders when compared to the control group. CONCLUSION: There is no specific finding for a specific type of vestibular lesion, but otolith function is affected in several disorders as measured by ocular counterrolling.

Adult↗
PubMed1999

[Bechterew phenomenon in the human].

BACKGROUND: Vestibuloocular and vestibulospinal reactions following the bilateral loss of vestibular function are designated as Bechterew's phenomenon. In vestibular physiology, under experimental conditions, this phenomenon has played an important role for understanding the mechanisms underlying vestibular compensation. However, clinical reports about this phenomenon in humans are extremely rare. PATIENTS AND METHODS: Bechterew's phenomen was observed throughout every stage of its development in a patient with consecutive bilateral loss of vestibular function. The disorder was documented by electronystagmography and posturography. DISCUSSION AND CONCLUSIONS: Bechterew's phenomenon depends on different states of vestibular function developing in a certain succession, whereby the varying relations between failure and compensation are decisive. The phenomen very impressively demonstrates the resilience of the central nervous system in adapting to varying peripheral functional states. From a clinical standpoint, knowledge of these relationships is important for understanding vestibular compensation.

Electronystagmography↗
PubMed1999

Correlation of chest radiographic findings with biopsy-proven acute lung rejection.

The purpose of this study was to determine the chest radiographic findings of acute rejection and the accuracy of chest radiography in making this diagnosis in patients undergoing lung transplantation. For each of 100 transbronchial biopsies performed on 25 lung transplant recipients (single lung in three, double lung in 22), chest radiographs obtained within 24 hours before the biopsy were reviewed retrospectively without knowledge of clinical or biopsy information. Transbronchial biopsy revealed 42 instances of acute rejection in 17 patients and 58 instances of no acute rejection (normal, n = 43; other processes, n = 15). All pulmonary parenchymal radiographic abnormalities were assessed. Acute rejection was associated with the presence of middle or lower lung reticular interstitial or airspace disease in 21 lungs (sensitivity = 0.50 [21/42]). This pattern was seen in 18 lungs without acute rejection (specificity = 0.69 [40/58]). There was no difference in the appearance of the lungs between grades 1 and 2 acute rejection. Normal lungs were noted in 20 instances of acute rejection (48%). The authors conclude that chest radiograph findings are abnormal in about 50% of instances of biopsy-proven acute rejection. Because the appearance of acute rejection is similar to that of other conditions, the diagnosis cannot be made accurately by chest radiography.

Acute Disease↗
PubMed1999

Characterization of the essential transport function of the AIDA-I autotransporter and evidence supporting structural predictions.

The current model for autodisplay suggests a mechanism that allows a passenger protein to be translocated across the outer membrane by coordinate action of a C-terminal beta-barrel and its preceding linking region. The passenger protein, linker, and beta-barrel are together termed the autotransporter, while the linker and beta-barrel are here referred to as the translocation unit (TU). We characterized the minimal TU necessary for autodisplay with the adhesin-involved-in-diffuse-adherence (AIDA-I) autotransporter. The assumed beta-barrel structure at the C terminus of the AIDA-I autotransporter was studied by constructing a set of seven AIDA-I-cholera toxin B subunit fusion proteins containing various portions of AIDA-I. Surface exposure of the cholera toxin B moiety was assessed by dot blot experiments and trypsin accessibility of the chimeric proteins expressed in Escherichia coli JK321 or UT5600. Export of cholera toxin B strictly depended on a complete predicted beta-barrel region. The absolute necessity for export of a linking region and its influence on expression as an integral part of the TU was also demonstrated. The different electrophoretic mobilities of native and denatured chimeras indicated that the proposed beta-barrel resides within the C-terminal 312 amino acids of AIDA-I. Together these data provide evidence for the predicted beta-barrel structure and support our formerly proposed model of membrane topology of the AIDA-I autotransporter.

Adhesins, Escherichia coli↗
PubMed1998

Class restriction of cephalosporin use to control total cephalosporin resistance in nosocomial Klebsiella.

CONTEXT: Resistance to most or all cephalosporin antibiotics in Klebsiella species has developed in many European and North American hospitals during the past 2 decades. OBJECTIVE: To determine if restriction of use of the cephalosporin class of antibiotics would reduce the incidence of patient infection or colonization by cephalosporin-resistant Klebsiella. DESIGN: A before-after comparative 2-year trial. SETTING: A 500-bed, university-affiliated community hospital in Queens, NY. PATIENTS: All adult medical and surgical hospital inpatients. INTERVENTION: A new antibiotic guideline excluded the use of cephalosporins except for pediatric infection, single-dose surgical prophylaxis, acute bacterial meningitis, spontaneous bacterial peritonitis, and outpatient gonococcal infection. All other cephalosporin use required prior approval by the infectious disease section. MAIN OUTCOME MEASURE: Incidence of patient infection or colonization by ceftazidime-resistant Klebsiella during 1995 (control period) compared with 1996 (intervention period). RESULTS: An 80.1% reduction in hospital-wide cephalosporin use occurred in 1996 compared with 1995. This was accompanied by a 44.0% reduction in the incidence of ceftazidime-resistant Klebsiella infection and colonization throughout the medical center (P<.01), a 70.9% reduction within all intensive care units (P<.001), and an 87.5% reduction within the surgical intensive care unit (P<.001). A concomitant 68.7% increase in the incidence of imipenem-resistant Pseudomonas aeruginosa occurred throughout the medical center (P<.01). All such isolates except one were susceptible to other antibiotics. CONCLUSION: Extensive cephalosporin class restriction significantly reduced nosocomial, plasmid-mediated, cephalosporin-resistant Klebsiella infection and colonization. This occurred at the price of increased imipenem resistance in P aeruginosa, which remained susceptible to other agents. Thus, an overall reduction in multiply-resistant pathogens was achieved within 1 year.

Adult↗
PubMed1998

[Postoperative vestibular compensation and facial nerve function after acoustic neuroma operation. Relation to origin of the tumors].

Within the battery of functional tests used in patients considered to have an acoustic neuroma, the use of vestibular examination has been reduced by the widespread use of magnetic resonance imaging. Especially small tumors often show normal or atypical results in electronystagmographic examinations (ENG). The purpose of the present study was to determine the diagnostic value of preoperative vestibular diagnosis in predicting the origin of an acoustic neuroma, as well as the duration of postoperative vestibular compensation and facial nerve function. Sixty-seven patients with intraoperatively confirmed tumor origins were examined preoperatively by ENG and electroneurography in addition to careful clinical examination. Group 1 (n = 45) consisted of patients with tumor originating from the inferior vestibular nerve and group 2 (n = 22) had tumor involving the superior vestibular nerve. Postoperatively, facial nerve function was determined by using the House grading system and vestibular function was defined by ENG 3, 6 and 12 months after surgery. Forty-seven percent of the patients in group 1 showed a pathologic caloric response compared to 64% in group 2. When patients had only a small tumor (< 1 cm), 27% of the patients in group 1 and 71% in group 2 had abnormal caloric results. Vestibular recovery was prolonged in group 1, but a statistically significant difference in postoperative facial nerve function could not be found. These findings confirm that especially small tumors arising from the inferior vestibular nerve can remain undetected by using ENG for diagnosis.

Electronystagmography↗
PubMed1998

[Quality of life after complex tibial reconstruction].

58 patients following Gustilo IIIB open tibial fractures, treated by serial debridements, osteosynthesis and microvascular free tissue transfer were investigated after an average of 6 years. Assessment of life satisfaction was done by means of a proven valid and reliable test instrument (FLZ-"Fragen zur Lebenszufriedenheit"). Further specific questions on treatment satisfaction, aesthetic result, occupation and income were added to this questionnaire. Significant discrepancies of the items recreational activities, income, occupation and partnership, productivity, mobility and pain were evaluated in comparison to available data of healthy west german population. The calculated global index of life satisfaction and health differed significantly from the established index of west german population. Although specific aspects like aesthetic result, donor site morbidity, pain and even function were critically judged, 91% of the patients were satisfied with the long term result of the treatment. None of the patients thought that an initial amputation probably might have been a better solution. The postrehabilitation employment rate was 64%. Limb salvage of Gustilo IIIB fractures by means of a multidisciplinary treatment protocol is able to afford useful and satisfying long time results. However, an impairment of quality of life, at least in specific items has to be considered.

Adolescent↗
PubMed1998

Use of electron spectroscopic imaging to determine element composition of the melanin granules in the stria vascularis of the guinea pig.

Electron spectroscopic imaging (ESI) was used to analyze the element content of melanin granules in the stria vascularis seen in ultrathin sections of Spurr-embedded cochleae of the guinea pig. To determine element composition, ESI images were taken at different ionization edges, and non-specific background signals were subtracted digitally by an image processing system. The presence of calcium and nitrogen in the melanin granules could be demonstrated clearly. The calcium identified in the melanin granules was then compared with the spatial distributions of calcium binding sites after the application of an antimonate precipitation method, which was used to localize loosely bound calcium. Despite a high calcium concentration within the granules, only very small single scattered calcium precipitates could be detected between these structures as compared with the amount of calcium precipitates attached to the plasma membrane or located within the cell nuclei. The nearly complete absence of precipitates within the melanin granules after the application of antimonate suggests differences in calcium binding and mobility involved in various physiological processes of ion balance regulation within the stria vascularis.

Animals↗
PubMed1998

Immunoelectron microscopic localization of nitric oxide synthase III in the guinea pig organ of Corti.

Nitric oxide synthase III (NOS III) was identified in the guinea pig cochlea on an ultrastructural level using a post-embedding immunolabeling procedure. Ultrathin sections of London Resin (LR) White-embedded specimens were incubated with various concentrations of a commercially available antibody to NOS III and the immunoreactivity visualized by a gold-labeled secondary antibody. Analysis of ultrathin sections of the organ of Corti in the second turn of the cochlea showed that NOS III could be localized in the endothelial cells of the blood vessels under the basilar membrane, which was comparable to its location in similar cells types in various biological systems. Besides this, NOS III was also found in the cytoplasm and in the nuclei of inner and outer hair cells. Immunoreactivity was not distributed homogeneously within receptor cells. Numerous gold particles could be identified at the border of the cuticular plates, in the middle parts of the stereocilia and in the cytoplasm. Gold-labeled anti-NOS III antibodies in these sites were seen mostly on the cytoplasmic side of the submembranous cisterns in the vicinity of mitochondria and in the central parts of the hair cells, whereas the cisterns were nearly free from any immunoreactivity. NOS III was also detected in the efferent and afferent nerve endings that were located at the basal and basolateral side of the outer hair cells. Some immunoreactivity was visible in different nerve fibers of the inner and outer spiral tunnels. Besides this, gold-labeled antibodies were also present in the cuticular plate of inner and outer pillar cells, in the cytoskeletal elements located in the apical parts of Deiters cells, forming the lamina reticularis, and in the cytoskeletal-containing region of the cytoplasm of those Deiters cells located at the basal side of the outer hair cells. The role of the NOS III immunoreactivity identified in the organ of Corti was consistent with respect to hair cell and tissue modulation.

Animals↗
PubMed1998

Possible Ca2+-dependent mechanism of apical outer hair cell modulation within the cochlea of the guinea pig.

Calcium ions were precipitated with potassium antimonate after injection of the inorganic calcium channel blocker MnCl2 or the inorganic potassium channel blockers BaCl2 or CsCl into the perilymph of the scala vestibuli of the guinea pig. The spatial distribution of the formed histochemical reaction products within the organ of Corti was studied by energy-filtering transmission-electron microscopy. Compared with untreated control ears, the number of the formed precipitates drastically increased at the extracellular side of the lamina reticularis after application of the various inorganic channel blockers. The apical side of the outer hair cells and the intervening Deiter cells were covered by a thick layer of calcium precipitates, whereas the number of histochemical reaction products was clearly reduced in the nearby acellular tectorial membrane. The high calcium content within the formed reaction products at the lamina reticularis could be demonstrated by elemental mapping and by electron energy-loss spectroscopy. To ascertain the alterations in the amounts of the calcium precipitates within the tectorial membrane after application of the various inorganic channel blockers, the precipitate densities were determined semiquantitatively by an image processing system and the values obtained compared with those of untreated control specimens. The observed histochemical results are in good agreement with published electrophysiological findings concerning the spatial distribution of ion channels located at the apical outer hair cell membrane. The detected alterations in the spatial distribution of calcium precipitates might correspond to calcium-dependent processes involved in outer hair cell modulation.

Animals↗
PubMed1998

High rate of chromosome abnormalities detected by fluorescence in situ hybridization using BCR and ABL probes in adult acute lymphoblastic leukemia.

The value of dual-color fluorescence in situ hybridization (FISH) with BCR and ABL probes for the detection of the Philadelphia (Ph) translocation and of other alterations involving ABL and/or BCR was evaluated in adult acute lymphoblastic leukemia (ALL). One hundred and four patients were studied prospectively using interphase nuclei FISH, chromosome analysis (CA), and PCR assays for the chimeric BRC/ABL transcript. FISH detected a Ph translocation in 24 cases (23.1%), as was confirmed by CA and/or PCR. FISH revealed a false positive diagnosis of a Ph translocation in four cases (5% false positive rate). Among 54 cases with combined FISH, CA and PCR assays, FISH failed to establish a correct diagnosis in 3.7%, PCR in 5.6%, and CA in 7.4%. The combination of two screening methods led to discrepant results in 9.3% (FISH + PCR), 11.1% (FISH + CA), or 13% (CA + PCR) of the cases. In seven of 80 (8.8%) Ph-negative patients, gain of BCR and/or ABL was identified. Overall, FISH detected alterations of the BCR and/or ABL genes with an incidence of 29.8% of the current study. Due to the possibility of false positive diagnosis of a Ph translocation using dual-color FISH the combination with chromosome and/or RT-PCR analyses is recommended in adult ALL patients.

Adolescent↗