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Biomedical subjects

R Hauser

Publications and source records attributed to R Hauser.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1997

Sperm quality in Hodgkin's disease versus non-Hodgkin's lymphoma.

The study was conducted to determine the deleterious effect of lymphoma disease on spermatogenesis and to evaluate the possibility that the disease is mediated primarily by inherent mechanisms in Hodgkin's disease and non-Hodgkin's lymphoma patients. A total of 89 patients with lymphoma disease (Hodgkin's and non-Hodgkin's) were referred for sperm preservation prior to adjuvant treatments. A comparison was made of pre- and post-thaw sperm quality between lymphoma patients and healthy volunteers who applied for sperm donation. This was followed by further assessment of the differences between patients with Hodgkin's disease and non-Hodgkin's lymphoma in terms of sperm variables, clinical parameters and blood hormone concentrations. It was found that patients with lymphoma disease had significantly impaired pre-freeze and post-thaw sperm quality compared with that of healthy volunteers. Patients with non-Hodgkin's lymphoma had spermatozoa of higher quality than patients with Hodgkin's disease. No differences were found in the clinical or hormonal parameters between these two groups. As expected, reduced testicular size and abnormal testicular consistency were correlated with decreased sperm quality. The mere presence of cancer disease has a direct negative effect on spermatogenesis, which is probably not related to incidental side-effects. A variable degree of impairment should be expected with different categories of cancer.

Adolescent↗
PubMed1997

Pregnancy resulting from frozen-thawed embryos achieved by intracytoplasmic injection of cryopreserved sperm cells extracted from an orchidectomized, seminoma-bearing testis, causing obstructive azoospermia.

A clinical pregnancy occurred in a 26-year-old patient after transfer of frozen-thawed embryos had been achieved by intracytoplasmic sperm injection (ICSI) of cryopreserved spermatozoa. These had been obtained from a testis removed due to seminoma. The couple applied to our fertility clinic for sperm cryopreservation before orchidectomy and radiotherapy. Unfortunately the husband was found to be azoospermic upon admission and sperm cells were extracted from the removed testis for use in our ICSI programme. This case represents a new aetiology for obstructive azoospermia that was successfully treated by ICSI. A pregnancy was established, resulting in successful birth.

Adult↗
PubMed1997

Testicular cancer and spermatogenesis.

We retrospectively analysed the characteristics of 54 men with testicular cancer. The group comprised 32 men with pure seminoma and 22 with non-seminoma germ cell tumours (NSGCT). This group was further compared to 190 healthy sperm donor candidates. Sperm quality was found to be higher in the seminoma versus the NSGCT patients in: sperm concentration [50 (0-230) versus 17 (0-288) x 10(6)/ml, P < 0.001], total motile sperm counts (TMC) [57 (0-508) versus 12 (0-854) x 10(6)/ejaculate, P = 0.002], post-thaw forward motile concentration [3 (0-28) versus 1.7 (0-17) x 10(6)/ml, P = 0.003] and motility percentage [20 (0-57) versus 12.5 (0-42) %, P = 0.002]. Serum hormone concentrations did not differ between these two sub-groups, although the follicle stimulating hormone concentrations were higher than normal in both (14.6 +/- 2.5 versus 10.4 +/- 1.4 mIU/ml, P > 0.05). As is well documented, cancer patients were found to have lower sperm quality compared to healthy candidates. The existence of these differences, and the fact that testicular cancer affects spermatogenesis, indicated that the mechanisms involved in the deterioration of sperm quality can, at least partially, be attributed to the type and origin of the malignant cancer. The higher sperm counts in the seminoma group may be related to the fact that the resemblance of the seminoma cells to normal germ cells is greater than that of the NSGCT cells, and therefore they retain a better capacity to function. Due to modern assisted reproductive technologies and micromanipulation achievements, the lower yield of spermatozoa in severe cases is no longer a major obstacle to offering cryopreservation to these patients.

Cryopreservation↗
PubMed1997

Noninvasive tracking of patient's head movements during computer-assisted intranasal microscopic surgery.

A noninvasive system designed for patient tracking during image-guided intranasal sinus surgery is described. It is based on optical digitizing with a custom-made registration and reference system, locatable surgical instruments, and a self-localizing operating microscope. Experimental and clinical results reveal a high degree of accuracy for the system. A mean spatial error of 0.82 +/- 0.31 mm was determined for repositioning of the reference system in a plastic model of the skull. For the positioning of the microscope, a mean error of 2.3 +/- 0.83 mm was calculated. Measurements of repositioning accuracy in 24 patients who received surgery for various sinus diseases had a mean spatial error of 1.56 +/- 0.76 mm. The 95% error interval for locating intranasal structures using the surgical instrument was 2.05 mm, and it was 4.92 mm using the microscope. These results suggest that the use of our noninvasive registration and reference system may be effective, accurate, and useful for noninvasive tracking of patient movements in computer-assisted intranasal surgery.

Head Movements↗
PubMed1997

A non-invasive patient registration and reference system for interactive intraoperative localization in intranasal sinus surgery.

A basic problem common to all systems for computer assisted surgery (CAS) is patient referencing, or the transfer of preoperative image data to the intraoperative pathology. The authors describe a highly precise CAS system with non-invasive referencing that can be used in ear, nose and throat (ENT) surgery of the paranasal sinuses. It is based on optical digitizing with several custom-made self-localizing surgical instruments. The accuracy of the system was tested in an experimental model using a plastic head. Measurements of repositioning the reference bow had a mean error of 0.81 mm +/- 0.31 mm. The system was evaluated clinically with 11 patients who received surgery for different pathologies of the paranasal sinuses. These trials met with a high rate of success and specific results are reported.

Biopsy↗
PubMed1997

Reproducibility of nasal peak inspiratory flow among healthy adults: assessment of epidemiologic utility.

STUDY OBJECTIVE: To assess the reproducibility of nasal peak inspiratory flow (PIFn). PARTICIPANTS: Twelve healthy nonsmoking volunteers were studied. METHODS: Repeated measurements of PIFn and oral (PIFm) peak inspiratory flow were performed for 5 consecutive days. Two methods of inhalation were compared. In the residual volume (RV) method, the forced maximal inspiratory maneuver was initiated from the end of a maximal expiration, while in the functional residual capacity (FRC) method, the maneuver was from the end of a tidal breath. Reproducibility was assessed by the intraclass correlation coefficient. Time trend for the 5 days was assessed by random effect models adjusting for different baseline for each subject. RESULTS: The intraclass correlation coefficient (ICC) of PIFn was 0.89 (lower limit of one-sided 95% confidence interval is 0.80) by the RV method and 0.78 (95% lower limit is 0.63) by the FRC method, suggesting that both methods have good reproducibility. These were similar to the ICCs of PIFm by each method. The FRC method did not show a significant time trend for PIFn. The RV method had a small, but significant, decreasing time trend of a magnitude considered inconsequential for the purpose of epidemiologic study. CONCLUSION: PIFn, measured from either RV or from FRC, showed good reproducibility and can be employed in epidemiologic studies investigating the upper airways' response to air pollutant exposure. Further studies of the relationships between PIFn and signs and symptoms of rhinitis are needed to evaluate the utility of this test for clinical and epidemiologic use.

Adult↗
PubMed1997

A novel chimaeric derivative of saruplase, rscu-PA-40 kDA/Hir, binds to thrombin and exerts thrombus-specific fibrinolysis in arterial and venous thrombosis in dogs.

The chimaeric molecule rscu-PA-40 kDA/Hir (M23) comprises the kringle and protease domain of saruplase (rscu-PA) and a thrombin inhibitory domain fused to the C-terminus of the protease domain. The 27 amino cid long thrombin inhibitory domain contains a sequence directed to the active site of thrombin and a fragment from the C-terminal region of hirudin. 125I-radiolabelled M23 (0.03 microM) bound to thrombin that was immobilised onto CNBr-activated sepharose beads. Unlabelled M23 (0.01-10 microM) and hirudin (0.001-10 microM) concentration-dependently displaced 125I-M23 from its binding to thrombin. Saruplase (up to 10 microM) did not influence the thrombin binding of M23. The fibrinolytic properties of M23 and saruplase were compared in anaesthetized dogs with femoral artery and saphenous vein thrombosis. Under concomitant heparinization, the intravenous bolus injections of 1 mg/kg M23 or saruplase induced reperfusion of thrombotically occluded femoral arteries in 4 out of 5 treated animals in each case. There was one reocclusion in the M23-treated group. Time to reperfusion (23 +/- 4 vs 25 +/- 11 min) and maximal height of reperfusion blood flow (98 +/- 21 vs 108 +/- 15% of baseline flow) did not differ significantly between the treatment groups. The time course of the lysis of incorporated 125I-fibrin radioactivity in thrombosed saphenous-veins was similar after bolus injections of M23 and saruplase. The maximal dissolution of 125I-fibrin in the venous thrombosis model was 91 +/- 1% in M23- and 88 +/- 5% in saruplase-treated animals. Plasma levels of fibrinogen were not influenced and alpha 2-antiplasmin levels were slightly reduced (-27 +/- 3%) after bolus injection of M23. In contrast, bolus injection of saruplase was accompanied by a significant decrease of fibrinogen (-55 +/- 19%) and alpha 2-antiplasmin (-75 +/- 11%) plasma levels. Template bleeding times virtually did not differ before (2.8 +/- 0.3 min) and 60 min after bolus injection of M23 (3.1 +/- 0.3 min), whereas treatment with saruplase resulted in a significant prolongation of template bleeding time from 2.6 +/- 0.2 min to 28 +/- 13 min. It is concluded that the saruplase derivative M23, while inducing equieffective thrombolysis after intravenous bolus injection in dogs, causes much fewer haemostatic side effects than its parent molecule. The high thrombus-specific activity of M23 is tentatively attributed to its affinity to clot-bound thrombin.

Animals↗
PubMed1997

[Esophageal obstruction after laxative administration].

Esophageal obstruction caused by food or foreign bodies is not uncommon in elderly patients. The esophageal obstruction is rarely caused by bulk laxatives, even though they are regularly prescribed to elderly patients. We report a case of a 69-year-old woman presenting as an emergency complaining of retrosternal discomfort and the inability to swallow or drink. Directly before contracting the problem, she had taken two teaspoons of Colosan mite, a laxative containing sterculia. We performed a rigid esophagoscopy, which revealed a complete obstruction by a gum like substance in the area of the upper esophagus sphincter. The laxative could be removed and the patient recovered without problems.

Administration, Oral↗
PubMed1996

Population studies of three AMPFLPs systems in a north Polish population.

Allele and phenotype frequencies for D1S80, D17S5 and ApoB were determined in a population sample of more than 200 unrelated persons from North Poland using the PCR method. For D1S80, D17S5 and ApoB 19, 13 and 21 alleles respectively were observed. No deviations from Hardy-Weinberg equilibrium were detected. All three systems have discrimination values above 92% and a cumulative discrimination index of 4.5 x 10(-4).

Alleles↗
PubMed1996

Different aspects of hearing preservation in surgery of vestibular schwannoma in women and men.

Pre-operative and postoperative auditory function was reviewed retrospectively in 98 patients with vestibular schwannomas. According to their hormonal status, women were categorized as "premenopausal" and "postmenopausal". Before surgery, 48% of the women (65% premenopausal) and 16% of the men presented with sudden hearing loss. The degree of auditory function before operation was similar for women and men. Preservation of pre-operative hearing was possible for 41% of the women (21% premenopausal) and 59% of the men. Further details of the surgery and the results of histopathological examination were also compared for women and men. Our results support substantial evidence that hearing preservation after surgery of vestibular schwannoma is easier to accomplish for men than for women. The finding of significantly more sudden hearing loss in premenopausal women may suggest a hormonal influence on tumour growth, which may also be partially responsible for the difference in hearing prognosis between women and men.

Adolescent↗
PubMed1996

[Computer-assisted surgery of the paranasal sinuses with an opto-electronic stereotaxic system].

BACKGROUND: A basic problem common to all systems for computer-assisted surgery (CAS) is the exact registration and referencing, that is, the transfer of preoperative image data to the intraoperative pathology. A system for computer-assisted ENT surgery should provide high precision as well as noninvasive registration and referencing. We present a system designed for such use in paranasal sinus surgery that is based on optical digitizing with several custom-made self-localizing surgical instruments. METHODS AND RESULTS: The system tracks the correct alignment of the head during CT data acquisition and continuously throughout surgery. A transformation matrix and a plane equation of the CT scan are used to match points of the object space to the image space detecting fiducial markers on the CT scans by an automatic algorithm. For position measurements a special reference frame and surgical instruments were developed and equipped with infrared light-emitting diodes that could be detected in real time. Measurements for repositioning of the reference system in a model and during real operations demonstrated a mean error ranging from 0.69 to 1.01 mm and from 0.76 to 1.67 mm respectively. Clinical experience with the application of the system for 15 patients who underwent surgery for different paranasal sinus pathologies is reported. CONCLUSIONS: Results suggest that the non-invasive reference system and the locatable surgical tools may be effective, accurate and useful for computer-assisted identification of intranasal structures. Such systems may contribute to further improvement of minimal invasive intranasal sinus surgery.

Equipment Design↗