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Biomedical subjects

R Hauser

Publications and source records attributed to R Hauser.

At least 55 records · Page 3Linked to original sources
PubMed1999

Pulmonary function in workers exposed to low levels of fuel-oil ash.

Previously, we reported significant lung function changes after exposure to fuel-oil ash during a boiler overhaul in which median PM10 and vanadium concentrations were 2.9 mg/m3 and 11.9 micrograms/m3, respectively. In this study, we examined prospectively 18 boilermakers involved in the short-term, partial overhaul of a large, oil-fired boiler where occupational exposures to PM10 and metals were relatively low. Vanadium and PM10 exposure levels were measured before and during boiler work. For PM10, median exposure before and during boiler work was 0.5 and 0.6 mg/m3, respectively. For vanadium, median exposure before and during boiler work was 1.0 and 12.7 micrograms/m3, respectively, comparable with the results of our previous study. Spirometric (PFT) testing was done three times: first day on the job (PFT1), end of overhaul (PFT2), and 2 weeks post-overhaul (PFT3). Spirometry results were analyzed using repeated measures analysis of variance. No significant differences were found. Boilermakers working on a short-term overhaul of an oil-fired boiler exhibited no significant change in any lung function parameter comparing pre-, during, and 2 weeks post-exposure. The comparatively low levels of exposure to PM10 and vanadium observed during boiler work, the short duration of the overhaul, and the healthy worker effect are possible explanations for these results.

Adult↗
PubMed1999

Optical tracking of a microscope for image-guided intranasal sinus surgery.

The objective of this study was to examine the effects of optical and tracking properties on the accuracy of an optically locatable operating microscope. The intraoperative arrangement was based on experimental results obtained from a skull model. Measurements were taken from 24 patients undergoing intranasal microscopic sinus surgery for various disorders. Two major groups of influencing factors were determined from measurements on the model: 1) optical properties of the microscope, such as the method of focal point adjustment, focal length, and magnification of the lens; and 2) tracking properties of the microscope, such as the distance of the digitizer to the tracked object, the number of reference infrared light-emitting diodes (IR-LEDs), and the area circumscribed by these IR-LEDs. Patient measurements showed an overall spatial error of 2.39+/-1.15 mm with a laser-supported adjustment of the focal point of the microscope. Although the associated 95th percentile was at 4.36 mm, such a value is encouraging for further development of microscopically navigable systems. It must be noted that the noninvasive patient-to-image registration was performed on the basis of a computed tomographic image with a slice distance of 2 mm.

Electronic Data Processing↗
PubMed1999

Evaluation of a new self-expandable silicone stent in an experimental tracheal stenosis.

STUDY OBJECTIVES: To assess the usefulness of an animal model for testing new tracheobronchial stents. SETTING: Animal laboratory of a university hospital. ANIMALS AND INTERVENTIONS: In a series with 12 mini-pigs, we induced a stable fibromalacic tracheal stenosis that was 50% to 70% of the normal tracheal diameter. After dilation we inserted a 16 x 40-mm self-expandable silicone stent into the stenotic part of the trachea in 10 of the mini-pigs. Five of the stents had a smooth outer surface, and five had additional silicone retaining spikes. Because of a long stenosis in two of the mini-pigs, two overlapping stents (one smooth and one with spikes) were inserted. MEASUREMENTS AND RESULTS: Stent deployment was successful and resulted in the disappearance of the slight to moderate stridor in all of the mini-pigs. Over a mean (+/- SD) observation period of 24 days (range, 10 to 41 days), all of the mini-pigs redeveloped stridor. Three of them died unexpectedly of suffocation: in all three a smooth stent had migrated, leading to total obstruction of the stenosis. In total, five of the six smooth stents migrated, and only one of the six spiked stents migrated. There was considerable granulation tissue formation at the ends of all of the stents. In the two control mini-pigs, a 12 x 35-mm Dumon stent was inserted. Both Dumon stents migrated, and one of them had considerable granuloma formation at its ends. At the end of the observation period, all stents were removed endoscopically and were found not to have deteriorated over time. CONCLUSIONS: Our model proved to be suitable for the evaluation of the technical aspects of the Polyflex stent. Spikes on the outer stent surface are more effective in preventing migration than smooth-surface stents. Long-term compatibility, however, seems to be difficult to test with our model because both the Polyflex and the Dumon stents had excessive granulation tissue formation at both ends, a factor which--in the case of the Dumon stent--does not occur to such a degree in benign human airway stenoses. Our results indicate a need for prospective long-term studies in benign human airway stenoses.

Animals↗
PubMed1998

In vivo import of unspliced tRNATyr containing synthetic introns of variable length into mitochondria of Leishmania tarentolae.

The mitochondrial genomes of trypanosomatids lack tRNA genes. Instead, mitochondrial tRNAs are encoded and synthesized in the nucleus and are then imported into mitochondria. This also applies for tRNATyr, which in trypanosomatids contains an 11 nt intron. Previous work has defined an exon mutation which leads to accumulation of unspliced precursor tRNATyr. In this study we have used the splicing-deficient tRNATyr as a vehicle to introduce foreign sequences into the mitochondrion of Leishmania tarentolae. The naturally occurring intron was replaced by synthetic sequences of increasing length and the resulting tRNATyr precursors were expressed in transgenic cell lines. Whereas stable expression of precursor tRNAsTyr was obtained for introns up to a length of 76 nt, only precursors having introns up to 38 nt were imported into mitochondria. These results demonstrate that splicing-deficient tRNATyr can be used to introduce short synthetic sequences into mitochondria in vivo. In addition, our results show that one factor which limits the efficiency of import is the length of the molecule.

Animals↗
PubMed1998

Urine vanadium concentrations in workers overhauling an oil-fired boiler.

Since fuel oil ash contains vanadium (V), the measurement of urinary levels of V may provide a biological marker in workers exposed to fuel oil ash. The usefulness of urine V samples as a biological monitoring tool ultimately depends on determining the appropriate time of sampling relative to when exposure occurs. Twenty boilermakers were studied during the overhaul of a large oil-fired boiler. A total of 117 urine samples were collected, 65 start-of-shift (S-O-S) and 52 end-of-shift (E-O-S) samples. Air V exposures were estimated with personal sampling devices and work history diaries. Air V concentrations ranged from 0.36 to 32.19 micrograms V/m3, with a mean +/- SD of 19.1 +/- 10.7, and a median of 18.5. On the first day of work on the overhaul, the V urine levels at the E-O-S (mean +/- SD were 1.53 +/- 0.53, median was 1.52 mg V/g creatinine) were significantly higher than those at the S-O-S (0.87 +/- 0.32, median was 0.83), P = 0.004. However, the V concentrations of the S-O-S urine samples on the last Monday of the study were not significantly different from the S-O-S urine levels on the previous Saturday, a time interval of about 38 hr between the end of exposure and sample collection. The Spearman correlation coefficient (r) between the S-O-S urine V and the workplace concentration of V dust during the previous day was r = 0.35. In summary, the results suggest a rapid initial clearance of V (elevating the E-O-S V concentration on the first day of work relative to the S-O-S concentration), followed by a slow clearance that is not complete 38 hr after the end of exposure, as evidenced by the Monday morning urine V concentrations. The Spearman correlations suggest that the S-O-S urine is preferred to the E-O-S urine for across-shift biological monitoring of V exposure.

Adult↗
PubMed1998

Pulmonary responses to oil fly ash particles in the rat differ by virtue of their specific soluble metals.

Occupational exposure to residual oil fly ash (ROFA) particulate has been associated with adverse respiratory health effects in humans. We hypothesized that ROFA collected at different sites within an oil burning power plant, by virtue of its differing metal and sulfate composition, will induce differential lung injury. Ten ROFA samples collected at various sites within a power plant were analyzed for water- and 1.0 M HCl-leachable arsenic (As), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), vanadium (V), zinc (Zn), and sulfur by inductively coupled plasma-atomic emission spectroscopy. All ROFA samples contained variable amounts of leachable (water-extractable) and 1.0 M HCl-extractable Fe, V, and/or Ni. All other metals, except Zn (ROFA No. 1 contained 3.43 and No. 3, 6.35 micrograms/mg Zn), were present in negligible quantities (< 1.0 microgram/mg) in the water extract. In vivo pulmonary injury from exposure to whole saline suspensions of these ROFA was evaluated. Male, SD rats (60 days old) were intratracheally instilled with either saline or saline suspension of whole ROFA (< 3.0 mass median aerodynamic diameter) at three concentrations (0.833, 3.33, or 8.33 mg/kg). After 24 h, lungs were lavaged and bronchoalveolar lavage fluid (BALF) was analyzed for cellular influx and protein content as well as lactate dehydrogenase (LDH) and N-acetyl glucosaminidase (NAG) activity and total hemoglobin as indicators of lung injury. ROFA-induced increases in BALF protein and LDH, but not neutrophilic inflammation, were associated with its water-leachable total metal, Ni, Fe, and sulfate content. However, the neutrophilic response following ROFA exposure was positively correlated with its water-leachable V content. Modest lung injury was observed with the ROFA samples which contained the smallest amounts of water-leachable metals. The ability of ROFA to induce oxidative burst in alveolar macrophage (AM) was determined in vitro using a chemiluminescence (CL) assay. AM CL signals in vitro were greatest with ROFA containing primarily soluble V and were less with ROFA containing Ni plus V. In summary, ROFA-induced in vivo acute pulmonary inflammation appears to be associated with its water-leachable V content; however, protein leakage appears to be associated with its water-leachable Ni content. ROFA-induced in vitro activation of AM was highest with ROFA containing leachable V but not with Ni plus V, suggesting that the potency and the mechanism of pulmonary injury will differ between emissions containing V and Ni.

Animals↗
PubMed1998

Expression of mannose-ligand receptors on human spermatozoa: effect of lecithin and association with sperm binding to the zona pellucida.

OBJECTIVE: To evaluate the change in the expression of mannose-ligand receptors and sperm binding capacity after the incubation of sperm cells with lecithin liposomes. DESIGN: A randomized, blinded-controlled experiment. SETTING: Andrology laboratory at the Lis Maternity Hospital. PATIENT(S): Fifteen fertile sperm donors and 10 subfertile men. INTERVENTION(S): Incubation of sperm samples with either control medium or 1 mg/mL of liposomal lecithin for 2 hours. MAIN OUTCOME MEASURE(S): Expression of mannose-ligand receptors as evaluated by mannosylated bovine serum albumin-fluorescein isothiocyanate and sperm binding to the zona pellucida as evaluated by the hemizona assay. RESULT(S): The mean +/- SE percentages of spermatozoa with patterns I, II, and III were 86% +/- 4.8%, 11% +/- 3.4%, and 3% +/- 1.6%, respectively, after treatment with control medium and 71% +/- 5.7%, 22% +/- 3.5%, and 7% +/- 2.5%, respectively, after treatment with lecithin. The same effect of lecithin was observed in the 10 sperm samples from subfertile men. The mean +/- SE numbers of sperm that bound to hemizonae after treatment with control medium or lecithin were 116 +/- 32.4 and 176 +/- 29.6, respectively. Statistically significant correlations were observed between the shift in patterns II and III and the enhancement of sperm binding after lecithin treatment (r = 0.44 and 0.6, respectively). CONCLUSION(S): Lecithin shifts the expression of mannose-ligand receptors to the capacitated and acrosoine-reacted patterns and enhances the binding capacity of the sperm cells.

Adult↗
PubMed1998

Sperm motility is a major determinant of pregnancy outcome following intrauterine insemination.

PURPOSE: Our purpose was to assess whether one or more sperm parameters have predictive value for the outcome of intrauterine insemination treatment. METHODS: Infertile couples whose normoovulatory and normomechanical female partners underwent superovulation and intrauterine insemination were investigated. The semen profile of the male partner was discounted. In 160 couples, 544 cycles were obtained, resulting in 59 ongoing pregnancies (10.84%/cycle, 36.87%/patient). RESULTS: The only parameter found to be significantly correlated with a positive outcome was the degree of sperm motility following preparation for intrauterine insemination. Close to half (47.5%) of the couples with a very good or an excellent degree of sperm motility conceived, whereas only 8.3% of those patients who had poor or fair sperm motility conceived. None of the semen characteristics, such as volume, count, percentage motility, or percentage normal morphology, were found to correlate with cycle outcome. Although there was a progressive increase in the pregnancy rate with an increase in the total number of motile sperm inseminated, it did not reach significance. Seventy percent of the pregnancies were achieved within a maximum of three treatment cycles. The spermatogram is not accurate enough as a prognostic factor for treatment outcome. CONCLUSIONS: The degree of sperm motility, after appropriate preparation for intrauterine insemination, is the only parameter to be correlated with treatment outcome. For couples with a normal female partner, we suggest a maximum of three treatment cycles of induction of ovulation and intrauterine insemination, whenever good progressive motile sperm is obtained after suitable preparation. For cases with poor sperm progression, we suggest appropriate couple counseling and that an alternative assisted reproduction procedure be taken into consideration.

Adult↗
PubMed1998

[Gastric pouch dilatation: complications after laparoscopic implantation of a silicone gastric band in pathologic obesity].

In 20 patients with morbid obesity a laparoscopic silicon gastric banding was installed using a LAP-BAND. All patients were examined postoperatively with water-soluble oral contrast material according to the usual protocol. 8 weeks after the operation a second control with thickened barium sulfate was added to measure and adjust the width of the silicon band. There were no early postoperative complications. But in the follow-up three patients presented with a pathologic gastric pouch-dilatation. This severe complication, which can have different etiologies, requires early detection and specific therapy.

Administration, Oral↗
PubMed1998

Multiple testicular sampling in non-obstructive azoospermia--is it necessary?

Spermatogenesis may be focal in non-obstructive azoospermia. The present study was conducted to determine whether the performance of multiple, rather than a single testicular sample contributes to obtaining spermatozoa in amounts sufficient for fertilization and cryopreservation in non-obstructive, azoospermic patients. Furthermore, the aim was to clarify the significance of location for retrieval from the testis in such cases. Three biopsies were taken from identical locations in 55 testes of 29 men with non-obstructive azoospermia: (i) the rete testis region, ii) the midline, and (iii) the proximal region of the testis. When sperm cells were detected, they were used for intracytoplasmic sperm injection (ICSI), and the remainder were then cryopreserved in as many aliquots as possible (adjusted for ICSI procedure). Spermatozoa were found in 28 testes (50.9%) of 18 men (62.1%). In the testes from which spermatozoa were obtained, they were present in three, two or one locations in 15 (53.6%), five (17.9%) and eight (28.6%) cases respectively. The possibility of finding spermatozoa was not influenced by the location in the testis. Multiple testicular sperm extraction is recommended in cases of non-obstructive azoospermia, since it may enhance diagnostic accuracy of absolute testicular failure and increase the number of sperm cells retrieved.

Adult↗
PubMed1998

Molecular markers of acute upper airway inflammation in workers exposed to fuel-oil ash.

Biomarkers in nasal lavage (NL) fluid may be useful in determining the presence and severity of upper airway inflammation. We studied 18 boilermakers overhauling a large, oil-fired boiler and 11 utility workers who served as controls for 6 wk. NL was performed before (NL1), during (NL2), and after (NL3) the overhaul. We measured nasal fluid levels of interleukins 6 (IL-6) and 8 (IL-8), eosinophilic cationic protein (ECP), and myeloperoxidase (MPO) as markers of response to fuel-oil ash exposure. In boilermakers, MPO was elevated during boiler work versus preboiler work (mean = 33.8 versus 22.7 ng/ml, p < 0.05), and at the 2-wk postexposure lavage (NL3) it had declined to 24.2 ng/ml (p = 0.08). Mean IL-8 levels increased in boilermakers between NL1 and NL2 (mean = 83.8 versus 134.8 pg/ml, p < 0.05), then decreased at NL3 (mean = 134.8 versus 89.0 pg/ml, p < 0.05). Nasal fluid vanadium increased in boilermakers between NL1 and NL2 (median < 1.0 versus 4.7 ppb, respectively, p < 0.05), then decreased at NL3 (median, 4.7 versus < 1.0 ppb, respectively, p < 0. 05). Levels of IL-6 and ECP did not change significantly during the study. Utility workers showed no significant change in any marker during the study period. Particulate matter < 10 micro(m) (PM10) levels were higher for boilermakers than for utility workers before boiler work (geometric mean (GM) = 0.40 versus 0.10 mg/m3, p < 0.05). This difference was more significant during boiler work (GM = 0.47 versus 0.13 mg/m3, p < 0.001). Ozone levels were low during the study. These data suggest that exposure to fuel-oil ash results in acute upper airway inflammation, potentially mediated by increased IL-8 levels and the recruitment and activation of polymorphonuclear leukocytes. These changes were associated with significantly increased PM10 levels and concentrations of upper airway vanadium.

Adult↗
PubMed1997

Leishmania tarentolae contains distinct cytosolic and mitochondrial glutaminyl-tRNA synthetase activities.

The intracellular distribution of glutaminyl-tRNA synthetases and their role in mitochondrial tRNA import were evaluated in the ancient eukaryote Leishmania tarentolae. The following results were obtained: (i) Glutaminyl-tRNA synthetase was detected in leishmanial mitochondria. This was unexpected because it has been postulated that, in organelles, Gln-tRNAGln is not formed by direct acylation of tRNAGln but by enzymatic transamidation of misacylated Glu-tRNAGln. (ii) Whereas the cytosolic extract is able to charge cytosolic and mitochondrial tRNAsGln, the mitochondrial matrix extract does not aminoacylate the cytosol-specific tRNAGln. This indicates that mitochondrial and cytosolic glutaminyl-tRNA synthetases are distinct. (iii) Seven of the 11 nucleotides that differ between the cytosolic and the mitochondrial tRNAGln are sufficient to convert the cytosol-specific tRNAGln into an optimal substrate for the mitochondrial enzyme. These nucleotides are arranged in three groups consisting of the nucleotides flanking the anticodon stem, the 5' nucleotide of the anticodon, and four nucleotides within the acceptor stem. And (iv), it was shown that the identity elements for recognition by the mitochondrial glutaminyl-tRNA synthetase do not overlap with a previously identified sequence segment required for mitochondrial import of the tRNAGln.

Amino Acyl-tRNA Synthetases↗
PubMed1997

High-frequency unilateral thalamic stimulation in the treatment of essential and parkinsonian tremor.

Pharmacologic treatment for essential tremor and the tremor of Parkinson's disease is often inadequate. Stereotaxic surgery, such as thalamotomy, can effectively reduce tremors. We performed a multicenter trial of unilateral high-frequency stimulation of the ventral intermedius nucleus of the thalamus in 29 patients with essential tremor and 24 patients with Parkinson's disease, using a blinded assessment at 3 months after surgery to compare clinical rating of tremor with stimulation ON with stimulation OFF and baseline and a 1-year follow-up. Six patients were not implanted because of lack of intraoperative tremor suppression (2 patients), hemorrhage (2 patients), withdrawal of consent (1 patient), and persistent microthalamotomy effect (1 patient). A significant reduction in both essential and parkinsonian tremor occurred contralaterally with stimulation. Patients reported a significant reduction in disability. Measures of function were significantly improved in patients with essential tremor. Complications related to surgery in implanted patients were few. Stimulation was commonly associated with transient paresthesias. Other adverse effects were mild and well tolerated. Efficacy was not reduced at 1 year. Chronic high-frequency stimulation is safe and highly effective in ameliorating essential and parkinsonian tremor.

Aged↗
PubMed1997

Frozen-thawed epididymal spermatozoa for intracytoplasmic sperm injection.

OBJECTIVE: To report the fertilization rate and pregnancy results for intracytoplasmic sperm injection (ICSI) cycles using frozen-thawed epididymal spermatozoa. DESIGN: Retrospective analysis of consecutive ICSI cycles. SETTING: Tertiary referral center for infertility. PATIENT(S): Infertile couples in whom 39 patients (59 ICSI cycles) required the use of frozen-thawed epididymal spermatozoa. As no cycles were performed using fresh epididymal spermatozoa, outcomes were compared with those of 130 couples (170 ICSI cycles) using fresh ejaculated spermatozoa for severe oligoasthenozoospermia-teratozoospermia, in which < 200,000 motile spermatozoa were retrieved after Percoll density gradient centrifugation. INTERVENTION(S): Epididymal sperm aspiration during microsurgery, followed by ICSI. MAIN OUTCOME MEASURE(S): Fertilization, embryo cleavage, ET, and clinical pregnancy rates (PRs). RESULT(S): A total of 484 metaphase II oocytes were injected with frozen-thawed epididymal spermatozoa, resulting in a two-pronuclear fertilization rate per injected metaphase II oocyte of 47%, significantly lower than in cycles using fresh ejaculated spermatozoa (73%). Embryo implantation rates (12.0% versus 13.3%) and clinical PRs per transfer (18.4% versus 27.0%) were not different. When the prefreeze vitality was > 20%, compared with lower vitality, both the fertilization (56% versus 22%) and embryo cleavage (91% versus 57%) rates were significantly greater. CONCLUSION(S): The routine collection and cryopreservation of epididymal spermatozoa at microsurgery allows multiple ICSI treatment cycles with success rates similar to those of ejaculated spermatozoa. However, when the vitality of aspirated spermatozoa is < 20%, the poor fertilization rates indicate the need to consider an alternative source of viable spermatozoa.

Adult↗
PubMed1997

[Speech audiometry with logatomes].

BACKGROUND: Logatomes are nonsense syllables used for analyzing the confusion of phonemes by hearing impaired listeners. They can provide a precise differentiation of phonemic confusions which may be useful in the exact adjustment of programmable hearing aids. METHODS: In this study, two lists of logatomes with 108 three-sound combinations with a structure of consonant-vowel-consonant (c-v-c) and vowel-consonant-vowel (v-c-v) were recorded on a compact disk. Twenty normally hearing adults and 28 patients with a sensorineural hearing loss were tested at a comfortable listening level of about 25 +/- 5 dB above the mean audiometric thresholds at 0,5. 1,0 and 2,0 kHz. An index of reduction of speech perception was calculated. RESULTS: A significant relationship between reduction of logatome perception and pure-tone audiometric thresholds at 1,2,3, and 4 kHz was demonstrated. Moreover, it was possible to distinguish between different groups of hearing impairment. CONCLUSIONS: The logatome test helps to analyze specific effects that hearing loss can have on the recognition of acoustic speech signals. The logatome test may become a valuable addition to speech audiometric tests with further standardization.

Adult↗