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Biomedical subjects

A Lindner

Publications and source records attributed to A Lindner.

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

Long-term follow-up of early treatment of unilateral forced posterior cross-bite. Orofacial status.

Twenty-nine subjects, 20 years old on average and all treated at 4 years of age for unilateral forced posterior dento-alveolar cross-bite by grinding or by expansion of the upper dental arch, were clinically examined to evaluate the long-term effects of their treatment. The frequency of successful treatment-indicated as stable correction of the cross-bite-by means of only 1 treatment sequence was 59%; by grinding, 57%; and by expansion, 60%. The 18 subjects that had only been treated at the age of 4 years formed the 'early group' in our study. Eleven of our subjects had been retreated later in the mixed or permanent dentition because of a relapse of the unilateral forced posterior cross-bite and formed the 'late group'. A significantly higher frequency of mouth breathing, breathing obstacles, and snoring was found in this group. According to our clinical investigation, 2 of the subjects in our cohort still had a unilateral forced posterior cross-bite. Our findings regarding masticatory performance, bite force, and endurance showed no significant differences between the initial cross-bite and the healthy sides or between the early and the late group subjects, which showed that the masticatory function of the treated subjects was symmetrical. Grinding and expansion treatments seem to display similar success rates in the long-term regarding correction of unilateral posterior forced cross-bite.

Adult↗
PubMed1999

Postoperative neuroimaging of high-grade gliomas: comparison of transcranial sonography, magnetic resonance imaging, and computed tomography.

BACKGROUND: A precise and comprehensive knowledge of tumor burden and its extent and growth pattern in the pre- and postsurgical states is required to optimize tumor therapy and to determine treatment success and failure. This prospective study compares the diagnostic potential of computed tomography (CT), magnetic resonance imaging (MRI), and transcranial sonography (TCS) in the postoperative follow-up of brain tumors. METHOD: Twenty-six patients with high-grade gliomas were included in the study. After tumor debulking, a total of 31 biopsy specimens were obtained from the resection margin in 21 patients and histological findings were compared with the findings of early postoperative TCS, CT, and MRI. Findings indicating residual tumor tissue were nonlinear contrast enhancement at the resection site revealed by CT or MRI or hyperechogenic lesions revealed by TCS. Follow-up examinations using all three imaging techniques were performed every 3 months. The end points of the follow-up were tumor recurrence as defined by CT and MRI, death, or severe clinical deterioration. RESULTS: On the basis of the above criteria, TCS identified residual tumor more often than did CT or MRI. In the group of 19 patients with histologically proven tumor remnants, residual tumor tissue was identified by TCS in all patients, whereas MRI and CT failed to show contrast enhancement in three and eight patients, respectively. However, the results of the TCS were false positive for one patient because of hemorrhage into the resection site. The average time to identification of tumor regrowth was 27 weeks using TCS, 29 weeks using CT, and 33 weeks using MRI. Only the differences between TCS and MRI reached statistical significance. For one patient, multicentric tumor recurrence was not detected using TCS. CONCLUSION: TCS may complement CT and MRI in the postoperative follow-up of patients with high-grade gliomas. Because none of these modalities alone is both sensitive and specific, an integrated analysis of imaging findings is recommended.

Adult↗
PubMed1999

Effects of conditioning horses with lactate-guided exercise on muscle glycogen content.

The effects of 3 different conditioning programmes on muscle glycogen concentration in horses were examined. Speed of exercise was selected according to the blood lactate values for each horse derived from a standardised exercise test before beginning a conditioning programme. Six 2-year-old Haflinger stallions were assigned randomly to one of 3 conditioning programmes according to a 6 x 3 latin square design: 45 min at their individual v1.5 or v2.5 and 25 min at v4. Each conditioning programme lasted 6 weeks (21 exercise sessions), followed by 5 weeks without conditioning (resting period). All exercise was carried out on a treadmill inclined at 17%. Muscle biopsies were taken 5 times from the gluteus medius muscle at 2 cm and 6 cm depth: before the start and in the middle of the conditioning period, then at Days 2, 9 and 35 after the last exercise session. It was found that glycogen concentration was not affected by conditioning until 9 days after finishing conditioning at v1.5 and v2.5 for 45 min (P < 0.05). By this time glycogen concentration in the muscle samples taken at 6 cm depth increased by 47 and 48%, respectively, and remained elevated until the end of the resting period. It was concluded that conditioning at lower intensity and for longer duration seemed to increase glycogen stores in the muscle while faster intensity but shorter duration exercise did not. To increase the likelihood of measuring effects of conditioning programmes on muscle variables, sampling should be done at different depths of a muscle and at several days after finishing a conditioning programme.

Animals↗
PubMed1999

Diagnostic yield of a 1-MHz transducer in evaluation of the basal cerebral arteries.

The authors examined the efficacy of a 1-MHz transducer in routine ultrasound monitoring. Fifty outpatients (34 women, 16 men; mean age, 65 +/- 2) with inadequate temporal bone window for examination with 2-MHz transducers were re-examined with a 1-MHz transducer. Additionally, 50 controls (34 men, 16 women; mean age 49 +/- 2) with adequate temporal bone window were examined with both the 1- and 2-MHz transducers. Signal quality was classified as good (GQ), adequate (AQ), or poor (PQ). Finally, 30 normal controls were examined with both transducers under standardized conditions, to evaluate potential differences in velocity measurements. A total of 90 temporal windows were lacking in the 50 patients. Use of the 1-MHz transducer resulted in identification of the middle cerebral artery in 68 cases (76%; PQ, n = 13; AQ, n = 29; GQ, n = 26), the anterior cerebral artery in 51 cases (57%; PQ, n = 23; AQ, n = 17; GQ, n = 11) and the posterior cerebral artery in 46 cases (51%; PQ, n = 12; AQ, n = 21; GQ, n = 13). Examination was feasible with both transducers in the 50 controls, with minimal differences in signal quality between the two transducers. Correlation between velocity values acquired with the 1- and 2-MHz transducers was significant for all vessels examined. Best values were measured for the middle cerebral artery, followed by the anterior cerebral artery and posterior cerebral artery. The authors conclude that the use of the 1-MHz transducer increases the yield of transcranial Doppler sonography.

Aged↗
PubMed1999

Ureteral catheterization and patient mobilization: is bed restriction mandatory?

OBJECTIVES: We determined whether patient mobilization influences ureteral catheter position in the collecting system. METHODS: 26 consecutive patients (28 renal units) who underwent ureteral catheterization for the purpose of retrograde pyelography or the relief of ureteral obstruction, were included. The position of the catheter's tip within the collecting system and versus the vertebrae was determined for each patient in the baseline supine position; standing upright, and supine again after walking a distance of 5 m. Catheteral displacement was determined by comparing its position in the upright and supine post-walking postures to its original position with the patient supine before any maneuver was undertaken. RESULTS: Assuming the upright position caused an average downward displacement of ureteral catheters by 7.8 mm (ranges 36 mm downward to 14 mm upward displacements, p = 0.0014). In the supine posture following a 5-meter walk, the catheters were downward displaced by 0. 36 mm on average (ranges 12 mm downward and 30 mm upward displacements p = 0.8). None of the ureteral catheters migrated below the uretero-pelvic junction during any phase of the above maneuvers. CONCLUSION: The position of ureteral catheters remains unchanged within the collecting system when patients stand or walk for 5 m. Therefore, mandatory bed restriction is not justified in patients with ureteral catheters.

Adolescent↗
PubMed1999

Prostate-specific antigen induces proliferation of peripheral blood lymphocytes and cytokine secretion in benign prostate hypertrophy patients.

PURPOSE: The etiology of benign prostatic hypertrophy (BPH) is still obscure. Data supporting an interaction connecting prostate hyperplasia and immune dysregulation is accumulating lately. The aim of the study was to assess the cellular immune responses to PSA by measuring the in vitro potential of PSA to induce proliferation and cytokine secretion in peripheral blood lymphocytes (PBLs) of BPH patients. MATERIALS AND METHODS: PBLs were extracted from fresh blood of 36 BPH patients and 11 age-matched controls. The PBLs were incubated with PSA. Proliferation of the cultured PBLs was determined by thymidine incorporation. Secretion of cytokines to the culture medium was measured either by biological assay (IL-2) or by ELISA (IL-4, IL-10, IFNgamma, TNFalpha). RESULTS: Twelve of the 36 BPH patients responded to PSA, whereas none of the 11 controls responded (p = 0.04). The proliferative response of PBLs from BPH patients was significantly higher as compared to PBLs of controls (p = 0.03). The mean total prostate volume and the transition zone volume were 51% and 54% bigger, respectively, among the responders to PSA as compared to the nonresponders (p < 0.05), whereas the mean serum PSA level did not differ significantly. PBLs of BPH patients secreted significantly higher levels of TNFalpha, both spontaneously and in response to PSA, as compared to controls (p = 0.003). CONCLUSIONS: These findings show that PSA is able to induce proliferation of PBLs in vitro in BPH patients. Moreover, the higher spontaneous and PSA-induced secretion of TNFalpha in BPH patients may reflect a role for this proinflammatory cytokine in vivo. Based on these observations, we suggest that autoimmune dysregulation might have a role in BPH.

Aged↗
PubMed1999

Neutral lipid from proteinuric rat urine is a novel inhibitor of the red blood cell calcium pump.

Proteinuria may be associated with hypertension and progression of renal insufficiency, which in turn may accompany abnormalities in cell calcium homeostasis. Therefore, urine from rats made proteinuric by puromycin aminoglycoside administration was analyzed, in a search for factors affecting cellular calcium transport. Proteinuric urine was fractionated by thin-layer chromatography and HPLC, and the effects of the fractions on the plasma membrane calcium pump in human red blood cells were assessed. Proteinuric urine contained a powerful specific inhibitor of the calcium pump that had little or no effect on the Na+/K+- or Mg2+-ATPases. The inhibitor was characterized as a neutral lipid, migrating as a single band, that inhibited 45Ca2+ efflux. To confirm the presence of an inhibitor in other proteinuric states, the urine from two patients with proteinuria was examined and subjected to chromatography as in the rat studies. These thin-layer chromatographic fractions contained a very strong inhibitor of the red blood cell calcium pump, suggesting that this substance may have relevance for the pathogenesis of proteinuric renal disease in human patients. Rat proximal tubule cells in tissue culture, when challenged with lipid-replete albumin, secreted an inhibitor of the calcium pump that migrated in the same chromatographic band as the urine factor. Therefore, the processing of fatty acids borne by albumin into endocytosing proximal tubular epithelium results in the synthesis and release of a previously unknown lipid modulator of the calcium pump, an effect that may predispose kidney tissue toward elevations in cytosolic calcium levels in target cells.

Adenosine Triphosphatases↗
PubMed1999

Relaxation of micro indentations in calcium oxalate urinary stones.

PURPOSE: We define energy requirements for stone micro indentation as a quantifiable event equivalent to in vivo energy delivery and investigate the change in indentation characteristics with time. MATERIALS AND METHODS: The 7 stones extracted from 7 patients were cut, embedded in resin and polished. Multiple micro indentations were performed on each stone section using a diamond Vickers micro indentor with a 500x light microscope and video system. The resulting indentations were observed by optical and scanning electron microscopy as a function of time. Organic matrix content was determined by dissolving stones in ethylenediaminetetraacetic acid solution. RESULTS: The energy requirement for stone indentation varies among stones (median range 43.6 to 109.9 kg/mm2) and at different locations in the same stone. Indentations relaxed by 10 to 70% during the first 2 weeks after indentation. Stones with a high organic matrix content were ductile and the phenomenon of indentation relaxation was pronounced. Brittle, low matrix stones relaxed to a lesser extent. CONCLUSIONS: The relaxation phenomena may have a practical implementation when considering repeat shock wave lithotripsy. A significant fraction of the energy invested in a stone which did not cause fracture or critical cracks is lost within 1 to 2 weeks after the procedure, particularly in elastic stones with a high organic matrix content. We suggest that the preferred interval for repeat shock wave lithotripsy be less than 2 weeks.

Calcium Oxalate↗
PubMed1998

Intracranial microembolic signals in patients with artificial heart valves: drowning in numbers.

Five years after the first description of Doppler microembolic signals, both their clinical significance and underlying material remain a matter of debate. It appears certain that MES depend on valve type and position, while their relation to other clinical parameters, including neurological complications, is still unclear. A number of clinical and experimental studies are reviewed, most of which argue towards gaseous embolic material.

Embolism, Air↗
PubMed1998

Further evidence of gaseous embolic material in patients with artificial heart valves.

OBJECTIVE: We undertook this study to evaluate the hypothesis that most microemboli signals in patients with artificial heart valves are gaseous, assuming that microemboli counts in cerebral arteries would progressively decline with increasing distance from the generating heart valve. METHODS: A total of 10 outpatients with CarboMedics (Sulzer Carbomedics Inc., n = 5) and ATS prosthetic heart valves (n = 5) in the aortic (n = 8), mitral (n = 1), or both aortic and mitral positions (n = 1) were recruited. Monitoring was performed simultaneously over the middle and anterior cerebral arteries and the common carotid artery for 30 minutes with the 2 MHZ transducers of a color duplex scanner (common carotid artery) and pulsed-wave Doppler ultrasonography (intracranial arteries). All data were harvested in an eight-channel digital audio tape recorder, and microembolic signal counts were evaluated online by two separate observers. RESULTS: Significantly higher microembolic signal counts were recorded in the common carotid artery (112 [75 to 175]) compared with the middle and anterior cerebral arteries (30 [18 to 36], p < 0.0001). Interobserver variability was satisfactory (k = 0.81). CONCLUSIONS: Our results strongly argue for gaseous underlying embolic material in patients with artificial heart valves because bubbles are bound to implode with time.

Adult↗
PubMed1998

The forgotten condyle: Delayed hypoglossal nerve palsy caused by fracture of the occipital condyle.

Fracture of the occipital condyle is a rare injury that can be easily overlooked. Palsies of lower cranial nerves can be the only symptom of the fracture. We report a patient with isolated post-traumatic hypoglossal nerve palsy who developed hypoglossal nerve palsy within 2 months after a car accident, indicating that the acute trauma itself did not damage the hypoglossal nerve. Most likely the palsy is caused by pressure to the nerve prior to the entry or within the hypoglossal canal. Since, in the present case, the fracture was stable and the patient showed only moderate neurological deficits, the operation was deferred.

Cranial Nerve Diseases↗
PubMed1998

Preoperative stereolithographic model planning for primary reconstruction in craniomaxillofacial trauma surgery.

High precision anatomical facsimile models of the patient's skull, individually produced by stereolithography, have been used in the preoperative planning in 16 patients with acute craniomaxillofacial trauma. In late primary repair, when open reduction and internal fixation had to wait for a decrease in facial swelling or cerebral oedema, computer-aided surgery has proven to be useful in terms of facilitating anatomical reduction, minimizing surgical approaches, saving operating time and leading to improved postoperative results, which may reduce the number of secondary corrections of post-traumatic deformities.

Acrylic Resins↗
PubMed1998

[Hearing loss as the leading symptom in anterior inferior cerebellar artery infarction].

Hearing impairment is a rare but characteristic symptom of vertebrobasilar occlusive disease. Two patients with anterior inferior cerebellar artery (AICA) infarction and hearing loss as presenting complaint, are described. In patient 1 progressive bilateral AICA infarction was caused by occlusion of the basilar artery, verified by transcranial Doppler sonography. Initial dizziness and bilateral hearing loss were followed by ataxia, dysarthria, dysphagia and right facial sensory impairment. Hearing loss improved during the second week, parallel to a temporary partial recanalisation of the basilar artery, but the patient subsequently developed further progressive brain stem symptoms and died. A right-sided AICA-infarction was diagnosed in patient 2. Initial symptoms were right-sided deafness and dizziness. Neurological examination revealed nystagmus, ataxia and involvement of th 5th and 6th cranial nerve. A progressive improvement of hearing loss and total recovery of the other brain stem symptoms was evident. In conclusion every patient with sudden hearing loss should be examined for additional brain stem symptoms since this can be the presenting sign of a life-threatening basilar artery thrombosis.

Aged↗
PubMed1998

Influence of transducer frequency on Doppler microemboli signals in an in vivo model.

The purpose of this study was the comparison between 1 MHz and 2 MHz transducers in the detection of Doppler microembolic signals (MES). Intraoperative monitoring was performed over the arterial tubing of the extracorporal circulation circuit in 10 patients undergoing coronary artery bypass surgery, using a pulsed ultrasound machine (DWL X-4). 1 MHz and 2 MHz probes were mounted to insonate sequential tubing segments and all monitoring sessions saved on digital audio tapes (DAT). MES counts and intensity as detected by each probe were subsequently evaluated. Specific interobserver agreement was assessed using Cohen's kappa-statistic. Time delay in the appearance of MES between the transducers was minimal (0-0.1 msec). A total of 5293 (64%) MES were detected by both probes, 2796 (33.8%) only with the 1 MHz and 181 (2.2%) only with the 2 MHz probe. Significant differences in MES intensity were evident when comparing the 1 MHz to the 2 MHz transducer (16.4 +/- 0.1 and 11 +/- 0.1 dB with the 1 MHz and 2 MHz transducers respectively, p < 0.0001). Specific interobserver agreement was satisfactory (k = 0.78). Use of 1 MHz instead of 2 MHz transducers increases the yield of embolus detection in vitro. Evaluation of the applicability and performance of this transducer in clinical settings is warranted.

Catheters, Indwelling↗
PubMed1998

Automated intraoperative detection of Doppler microembolic signals using the bigate approach.

BACKGROUND AND PURPOSE: We undertook this study to evaluate the performance of an automated detection software in the detection of Doppler microembolic signals (MES) during cardiac surgery. METHODS: Intraoperative monitoring was performed over two spatially separated vessel segments of each middle cerebral artery in 18 patients undergoing coronary artery bypass surgery (n= 16) or cardiac valve replacement (n=2). All monitoring sessions were saved on digital audiotape and subsequently played back to the same ultrasound machine, set up to automatically detect MES by evaluating the temporary delay in their appearance between the two segments, in the presence of an experienced examiner. Software sensitivity and specificity in MES detection were then evaluated, with the results of the human observer considered the gold standard. RESULTS: A total of 44,933 high-intensity signals (artifacts and MES) were evaluated. Overall sensitivity and specificity of the software, with the human observer considered the gold standard, were 64% and 78.5%, respectively, ranging from 54% to 96% and from 74% to 90% in individual patients. When the overall results of the software were compared with those of the human observer, kappa was 0.72. CONCLUSIONS: The tested software displayed a satisfactory specificity. Provided that the sensitivity is further improved, it could provide a valuable tool in intraoperative monitoring.

Artifacts↗
PubMed1998

Differentiation between intracerebral hemorrhage and ischemic stroke by transcranial color-coded duplex-sonography.

BACKGROUND AND PURPOSE: The differential diagnosis of intracerebral hemorrhage versus ischemic stroke has critical implications for stroke management. Transcranial color-coded duplex sonography (TCCS) has been shown to identify intracerebral hemorrhages and intracerebral vessel occlusions. We conducted this study to evaluate the sensitivity and specificity of TCCS in this differential diagnosis and in the detection of stroke complications. METHODS: One hundred fifty-one patients (58 women, 93 men; mean age, 65.6 years [range, 32 to 89 years] ) with acute hemiparesis were enrolled in this prospective study. On admission all patients had a complete neurological examination. A cranial CT scan and a sonographic examination of the brain parenchyma and all extracranial and intracranial cerebral arteries were conducted. The sonographer was blinded for the radiological findings. RESULTS: According to CT criteria, 60 patients had an intracerebral hemorrhage and 67 patients had an ischemic stroke, and in 24 patients CT findings were inconclusive, showing neither bleeding nor an ischemic stroke. On sonographic examination, 18 patients (12%) had no sufficient acoustic bone window. Of the remaining 133 patients, 126 (95%) were diagnosed correctly by sonography in agreement with CT. Sonography missed 3 atypical bleedings (2 with upper parietal location). In 4 patients without bleeding, an intracerebral hemorrhage was suspected by TCCS because of increased white matter echo density due to microangiopathy. Stroke complications depicted by CT (disturbance of cerebrospinal fluid circulation, hemorrhagic transformation, midline shift, ventricular bleeding) (n=54) were correctly shown by TCCS in 45 patients (83%). No complication was missed that would have required further treatment. CONCLUSIONS: In comparison to the "gold standard" of CT, TCCS identified stroke complications and differentiated between intracerebral hemorrhage and ischemic stroke with reasonable sensitivity. Thus, if CT is not readily available, TCCS may complement clinical examination in patients with acute stroke. In addition, it may also be useful in detecting stroke complications in the follow-up of stroke patients.

Adult↗