Biomedical subjects

W Schulze

Publications and source records attributed to W Schulze.

At least 19 recordsLinked to original sources

PubMed2006

A new paradigm for profiling testicular gene expression during normal and disturbed human spermatogenesis.

The aim of this study was to identify gene expression patterns of the testis that correlate with the appearance of distinct stages of male germ cells. We avoided the pitfalls of mixed pathological phenotypes of the testis and circumvented the inapplicability of using the first spermatogenic wave as done previously on rodents. This was accomplished by using 28 samples showing defined and highly homogeneous pathologies selected from 578 testicular biopsies obtained from 289 men with azoospermia (two biopsies each). The molecular signature of the different developmental stages correlated with the morphological preclassification of the testicular biopsies, as shown by resampling-based hierarchical clustering using different measures of variability. By using analysis of variance (ANOVA) and extensive permutation analysis, we filtered 1181 genes that exhibit exceptional statistical significance in testicular expression and grouped subsets with transcriptional changes within the pre-meiotic (348 genes), post-meiotic (81 genes) and terminal differentiation (38 genes) phase. Several distinct molecular classes, metabolic pathways and transcription factor binding sites are involved, depending on the transcriptional profile of the gene clusters that were built using a novel clustering procedure based on not only similarity but also statistical significance.

Azoospermia↗

PubMed2006

Multicolor fluorescence in situ hybridization (M-FISH) on cells from urine for the detection of bladder cancer.

Bladder cancer is the fifth most common cancer in adults. Because of the high recurrence rate (up to 70%) new tumor markers for urine are necessary for monitoring patients. In this study, we investigated the value of M-FISH on cells from urine for the detection of bladder cancer. Urine samples from 141 patients suspicious of bladder cancer were analyzed in this study. Cells were isolated from urine before surgical therapy. For FISH analysis, a commercial kit (UroVysion) containing hybridization probes for chromosomes 3, 7, 9p21 and 17, was used. Twenty-five cells were analyzed in each case by two observers. A FISH result was obtained in 121 cases. Overall, sensitivity was 60% and specificity reached 82.6%. Sensitivity and specificity by cytology were 24.1% and 90.5%, respectively. Analyzing results concerning T-category, sensitivity of FISH and cytology was 36.1% and 15% in pTa, 65.2 and 25.7% in pT1, 100% and 66.7% in pT2-3 tumors, respectively. Concerning tumor grade, similar results were obtained: sensitivity was 37% and 14% in G1, 65.4% and 40% in G2, 91.7% and 50% in G3 tumors, for FISH and cytology, respectively. In conclusion, FISH on cells from urine has been shown in all studies to be highly sensitive and specific for detection of bladder cancer. Sensitivity of FISH is higher than conventional cytology and can be used in routine diagnosis additionally to conventional cytology especially in doubtful or negative cases. FISH can detect recurrence earlier than other methods like cytology, cystoscopy or biopsy histological examination.

Cell Nucleus↗

PubMed2003

[The role of the tibiofibular syndesmotic and the deltoid ligaments in stabilizing Weber B type ankle joint fractures--an experimental investigation].

The purpose of the present biomechanical investigation was to check the functional importance of the syndesmosis ligaments and of the deltoid ligament for ankle fracture type B according to the AO-Weber classification. We constructed a special fixation clamp, with 12 fresh and unembalmed lower legs being tested for lateral shift (mm) and ten for tibiotalar rotation. All specimens were exposed in the same neutral position. Transverse loads (F(y)) varied between 0 and 150 N, axial loads (F(z)) between 0, 300, 600 and 1,000 N and rotational loads (F(r)) between 2.4 and 4.9 Nm. All series were repeated according to supination-eversion (SE) injury patterns of the Lauge-Hansen classification. Syndesmotic ligaments and the fibula were incrementally sectioned from anterior to posterior. Type SE I consisted of an isolated incision of the anterior syndesmosis ligament. Type SE II had an additional oblique fracture of the fibula at the height of the tibiofibular syndesmosis. In type SE III injuries, in addition to the fibular fracture, a complete rupture of the syndesmosis ligaments was present, and for type SE IV lesions the deltoid ligaments were incised. The transverse load-displacement curve was s-shaped in all uninjured joints,with the highest gradient between 10 and 20 N with no axial compression. Without axial compression in cases of F(y)=25 N transverse loads, the mean talus translation was 0.51 mm. Following type II injuries, the average talus translation was 0.68 mm (not significant) and rose to an average of 0.95 mm ( P <0.01) in type III injuries. After additional incision of the deltoid ligaments, the ankle joint subluxed permanently when more than 5-10 N transverse loads were applied. Axial loads of 300 N or more resulted in a considerable reduction in talus translations, indicating increased stability and congruency within the joint complex. In this way, the vertical loading of the ankle joints always contributed to joint stability. The average internal tibiotalar rotation reached with a torque of 2.4 Nm was 3.52 degrees and with 4.9 Nm 5.15 degrees when no axial compression was applied. External rotation measured -6.36 degrees and -8.62 degrees, respectively. Following the experimental protocol, significant increases were noted for external rotation at SE II degrees injuries ( P =0.003) and for internal rotation at SE III degrees ( P =0.03) injuries. Our data support the proposition that the deltoid ligaments and the posterior syndesmosis play a key role in the stability of ankle fractures for supination-eversion injuries. If these structures remain intact, conservative and early functional treatment are recommended in patients with minimal (<2 mm) or no fracture displacement. This concept is confirmed by the literature dealing with clinical mid- and long-term follow-up studies.

Ankle Injuries↗

PubMed2003

Megalospermatocytes in the human testis exhibit asynapsis of chromosomes.

Testis biopsies of three infertile patients were identified, which showed a predomination of megalospermatocytes in the seminiferous tubules. Megalospermatocytes are very large primary spermatocytes indicating a spermatogenic arrest. Because of the high percentage of these germ cells it was possible to apply a whole-mount spreading technique to investigate the chromosomal pairing behaviour in prophase I of meiosis. It could be shown that most of the megalospermatocytes exhibited extensive chromosomal asynapsis, suggesting that a characteristic meiotic disorder may give rise to reduced fertility, or even infertility.

Adult↗

PubMed2002

Quantification of telomerase activity, porphobilinogen deaminase and human telomerase reverse transcriptase mRNA in testicular tissue - new parameters for a molecular diagnostic classification of spermatogenesis disorders.

The aim of the study was to evaluate the quantitative detection of human telomerase reverse transcriptase (hTERT) mRNA and telomerase activity as new molecular diagnostic parameters for a subclassification of spermatogenesis disorders. Telomerase activity was detected by a quantitative telomerase PCR ELISA, and hTERT mRNA expression was quantified by fluorescence real-time RT-PCR in a LightCycler in cryopreserved testicular tissue specimens. This was paralleled by a histological workup. The discriminant analysis showed that detection of normalized hTERT expression was able to correctly classify 89.0% of the investigated tissue specimens into the subgroups of full spermatogenesis, maturation arrest or Sertoli-cell-only syndrome. In contrast, discriminant analysis revealed an only 58% accuracy of telomerase activity for the investigated tissue specimens. This study shows that the quantification of hTERT expression in testicular tissue by real-time fluorescence RT-PCR is well suited for correctly classifying spermatogenesis disorders and proved to be markedly superior to the determination of telomerase activity.

Biopsy↗

PubMed2002

Quantification of the expression level of the gene encoding the catalytic subunit of telomerase in testicular tissue specimens predicts successful sperm recovery.

BACKGROUND: The objective of the present study was to evaluate the quantitative detection of human telomerase reverse transcriptase (hTERT) mRNA as a new molecular diagnostic parameter in the work-up of testicular tissue specimens from patients presenting with non-obstructive azoospermia. M ETHODS: hTERT mRNA expression was quantified in 49 cryopreserved testicular tissue specimens by fluorescence real-time RT-PCR in a LightCycler. This was paralleled by conventional histological work-up in all tissue specimens and additional semithin sectioning preparation in cases with maturation arrest (n = 20) and Sertoli cell-only syndrome (SCOS; n = 12). RESULTS: The average normalized hTERT expression (N(hTERT)) was 136.1 +/- 41.7 copies (mean +/- standard deviation) in tissue specimens with presence of haploid germs cells, N(hTERT) = 48.2 +/- 21.0 copies in those with maturation arrest and N(hTERT) = 2.7 +/- 2.8 copies in those with SCOS. The discriminant analysis showed that detection of N(hTERT) was able correctly to classify 89.0% of the investigated tissue specimens. CONCLUSIONS: Our results demonstrate that quantitative detection of hTERT mRNA expression in testicular tissue enables a molecular-diagnostic subclassification of spermatogenesis disorders. Quantitative detection of hTERT in testicular biopsies is thus well suited for predicting successful sperm recovery in patients with azoospermia and is a useful molecular diagnostic parameter for supplementing the histopathological evaluation.

Adult↗

PubMed2002

Injury prophylaxis in paragliding.

OBJECTIVES: To show trends in paragliding injuries and derive recommendations for safety precautions for paraglider pilots on the basis of accident statistics, interviews, questionnaires, medical reports, and current stage of development of paragliding equipment. METHODS: All paragliding accidents in Germany have to be reported. Information on 409 accidents was collected and analysed for the period 1997-1999. RESULTS: There was a substantial decrease in reported accidents (166 in 1997; 127 in 1998; 116 in 1999). The number of accidents resulting in spinal injuries was 62 in 1997, 42 in 1998, and 38 in 1999. The most common cause of accident was deflation of the glider (32.5%), followed by oversteering (13.9%), collision with obstacles (12.0%), take off errors (10.3%), landing errors (13.7%), misjudgment of weather conditions (4.9%), unsatisfactory preflight checks (4.9%), mid-air collisions with other flyers (2.2%), accidents during winching (2.2%), and defective equipment (0.5%). Accidents predominantly occurred in mountain areas. Fewer than 100 flights had been logged for 40% of injured pilots. In a total of 39 accidents in which emergency parachutes were used, 10 pilots were seriously injured (26%) and an additional three were killed (8%). CONCLUSIONS: Injuries in paragliding caused by unpredictable situations can be minimised by (a) using safer gliders in the beginner or intermediate category, (b) improving protection systems, such as padded back protection, and (c) improving pilot skills through performance and safety training.

Accidents, Aviation↗

PubMed2001

Ag8 fluorescence in argon.

The fluorescence of Ag8 in an argon matrix and in argon droplets is reported. This is the first unambiguous assignment of the fluorescence of a metal cluster larger than the tetramer, indicating that the excited state lifetime is longer than previously thought. It is discussed as a possible result of a matrix cage effect. The excitation spectrum is compared with two-photon-ionization measurements of Ag8 in helium droplets and to known absorption data. The agreement is excellent. We propose that the excited states relax rapidly through vibrational coupling to a long-lived state, from which the fluorescence occurs.

Journal Article↗

PubMed2001

Phonotaxis during walking and flight: are differences in selectivity due to predation pressure?

Female selectivity was tested in Tettigonia viridissima during two different phonotaxis situations; compensated walking and tethered flight. For two of the three temporal parameters that are important for call recognition in T. viridissima, selectivity was similar in the two situations. Selectivity for the third parameter (minimum interval duration between the double pulses) was much higher during walking than during flight: walking females responded only to stimuli with intervals of 28 ms or longer, while call models with intervals of 18 ms were attractive during flight. One interneuron (TN-1) is probably involved in filtering the minimum interval duration. As this neuron is also the most likely candidate for transmitting bat calls during flight, it is suggested that the selectivity differences between walking and flying might be due to the need for detecting predator signals during flight, when TN-1 would be occupied listening for bats. With TN-1 unavailable for song processing during flight, temporal selectivity for the minimum interval duration should be reduced, as was found here.

Animal Communication↗

PubMed2001

Inducible nitric oxide synthase in the myocard.

Recognition of significance of nitric oxide synthases (NOS) in cardiovascular regulations has led to intensive research and development of therapies focused on NOS as potential therapeutic targets. However, the NOS isoform profile of cardiac tissue and subcellular localization of NOS isoforms remain a matter of debate. The aim of this study was to investigate the localization of an inducible NOS isoform (NOS2) in cardiomyocytes. Employing a novel immunocytochemical technique of a catalyzed reporter deposition system with tyramide and electron microscopical immunocytochemistry complemented with Western blotting and RT-PCR, we detected NOS2 both in rat neonatal and adult cultured cardiomyocytes and in the normal myocard of adult rats as well as in the human myocard of patients with dilative cardiomyopathy. NOS2 was targeted predominantly to a particulate component of the cardiomyocyte--along contractile fibers, in the plasma membrane including T-tubules, as well as in the nuclear envelope, mitochondria and Golgi complex. Our results point to an involvement of NOS2 in maintaining cardiac homeostasis and contradict to the notion that NOS2 is expressed in cardiac tissue only in response to various physiological and pathogenic factors. NOS2 targeting to mitochondria and contractile fibers suggests a relationship of NO with contractile function and energy production in the cardiac muscle.

Animals↗

PubMed2001

Expression of alpha1-adrenergic receptor subtypes in heart cell culture.

Three alpha1-AR subtypes have been cloned so far and are designated as alpha1a, alpha1b,, and alpha1d. Organ-specific distribution pattern and subtype-specific effects are known but not fully understood. To address a cell-type specific expression pattern in the heart we investigated expression pattern of alpha1-AR subtypes on RNA- and protein-level in heart tissue, cultured cardiomyocytes and non-myocytes of the rat. Each alpha1AR-subtype mRNA was present in neonatal and adult rat heart culture but the relative distribution pattern was significantly different. While the alpha1a-AR subtype is preferentially expressed in adult cardiomyocytes, the alpha1b-AR subtype was preferentially expressed in the non-myocyte cell fraction. The RT-PCR results were confirmed by Western-blotting (alpha1b) and immunocytochemical studies. Incubation with an alpha1-agonist (phenylephrine) for 72 h led to a significant reduction of the alpha1b-AR in neonatal heart cell culture on both mRNA and protein level. In contrast, incubation with an alpha1-antagonist (prazosin) induced a 1.6 fold upregulation of the alpha1a-AR mRNA without significant effects on radioligand binding and functional assay. The results indicate a distribution pattern of the alpha1-AR subtype which is specific for cell type and ontogeny of the rat heart and may be regulated by adrenergic agents.

Animals↗

PubMed2001

Effects of various cryopreservation media and freezing-thawing on the morphology of rat testicular biopsies.

Currently, testicular sperm extraction is successfully combined with intracytoplasmic sperm injection into the oocyte (ICSI). Several pieces of a testicular biopsy can be frozen and thawed until the ICSI attempt. In this study, the effects of freezing-thawing on the morphology of rat testicular biopsies stored in different cryopreservation media were analysed. Each cryopreservation medium contained glycerol and/or dimethyl sulfoxide (DMSO) as cryoprotectants. In general, both glycerol and DMSO, when applied at moderate concentrations (6-25%), preserved the structure of the seminiferous epithelium. The freezing-thawing procedure had no significant effect on tubular diameter; however, it caused a 'folding' of the lamina propria and notable damage to Sertoli cells, spermatogonia and spermatocytes. Round and elongated spermatids and spermatozoa displayed occasional nuclear damage, vacuolization, and shrinkage/swelling of the cytoplasm. However, the vast majority of these cells maintained their normal structure in nearly all the applied cryomedia. It is concluded that freezing-thawing of testicular biopsies, and the cryopreservation medium, have a significant impact on the structure of the seminiferous epithelium, particularly on its basal compartment.

Animals↗

PubMed2001

[Complications in the use of the halo fixator].

50 patients out of a total of 88 who underwent treatment using a halo-fixateur between 1987 and 1997 were available for a follow-up interview reviewing local complications and quality of life. Marginal discomfort was observed in 54% of patients, moderate complaints/transitory pain in 30%, prolonged and severe discomfort and pain in 16%. 62% of patients took no analgetics, 22% infrequently, and 16% continuously throughout treatment. In pin-tract infection local treatment was successful in 6 patients, in 3 patients the screws needed to be relocated. Complaints of dysphagia due to extended forced lordosis of the cervical spine could be corrected by adjusting the position of the halo ring in 3 out of 8 patients. 3 patients developed pressure sores which could be managed without surgical intervention. Proper fixation and placement of the pin-tracts are crucial in the application of the halo fixateur if complications are to be avoided. Superficial infections must be treated locally. If the infection persists immediate pin relocation and systemic antibiotic therapy have to be initiated.

Adolescent↗

PubMed2001

Quantification of insect nitrogen utilization by the venus fly trap Dionaea muscipula catching prey with highly variable isotope signatures.

Dionaea is a highly specialized carnivorous plant species with a unique mechanism for insect capture. The leaf is converted into an osmotically driven trap that closes when an insect triggers sensory trichomes. This study investigates the significance of insect capture for growth of Dionaea at different successional stages after a fire, under conditions where the prey is highly variable in its isotope signature. The contribution of insect-derived nitrogen (N) was estimated using the natural abundance of 15N. In contrast to previous 15N studies on carnivorous plants, the problem emerges that delta15N values of prey insects ranged between -4.47 per thousand (grasshoppers) and +7.21 per thousand (ants), a range that exceeds the delta15N values of non carnivorous reference plants (-4.2 per thousand) and soils (+3 per thousand). Thus, the isotope-mixing model used by Shearer and Kohl to estimate the amount of insect-derived N is not applicable. In a novel approach, the relationships of delta15N values of different organs with delta15N of trapping leaves were used to estimate N partitioning within the plant. It is estimated that soon after fire approximately 75% of the nitrogen is obtained from insects, regardless of plant size or developmental stage. The estimates are verified by calculating the average isotope signatures of insects from an isotope mass balance and comparing this with the average measured delta15N values of insects. It appears that for Dionaea to survive and reach the flowering stage, seedlings must first reach the 6th-leaf rosette stage, in which trap surface area nearly doubles and facilitates the capture of large insects. Large amounts of nitrogen thus made available to plants may facilitate an enhanced growth rate and the progressive production of additional large traps. Dionaea reaches a maximum abundance after fire when growth of the competing vegetation is suppressed. About 10 years after fire, when grasses and shrubs recover, Dionaea becomes overtopped by other species. This would not only reduce carbon assimilation but also the probability of catching larger prey. The amount of insect-derived nitrogen decreases to 46%, and Dionaea becomes increasingly dependent on N-supply from the soil. Competition for both light and N may cause the near disappearance of Dionaea in older stages of the fire succession.

Animals↗

PubMed2001

High deletion frequency of the complete AZFa sequence in men with Sertoli-cell-only syndrome.

We have developed a rapid screening protocol for deletion analysis of the complete AZFa sequence (i.e. 792 kb) on the Y chromosome of patients with idiopathic Sertoli-cell-only (SCO) syndrome. This Y deletion was mapped earlier in proximal Yq11 and first found in the Y chromosome of the SCO patient JOLAR, now designated as the AZFa reference patient. We now show that similar AZFa deletions occur with a frequency of 9% in the SCO patient group. In two multiplex polymerase chain reaction experiments, deletions of the complete AZFa sequence were identified by a typical deletion pattern of four new sequence-tagged sites (STS): AZFa-prox1, positive; AZFa-prox2, negative; AZFa-dist1, negative; AZFa-dist2, positive. The STS were established in the proximal and distal neighbourhoods of the two retroviral sequence blocks (HERV15yq1 and HERV15yq2) which encompass the break-point sites for AZFa deletions of the human Y chromosome. We have found deletions of the complete AZFa sequence always associated with a uniform SCO pattern on testicular biopsies. Patients with other testicular histologies as described in the literature and in this paper have only partial AZFa deletions. The current AZFa screening protocols can therefore be improved by analysing the extension of AZFa deletions. This may provide a valuable prognostic tool for infertility clinics performing testicular sperm extraction, as it would enable the exclusion of AZFa patients with a complete SCO syndrome.

Chromosomes, Artificial, Bacterial↗

PubMed2001

Osteoid osteoma that occurred in a former fracture site.

Diagnosis of osteoid osteoma often is delayed, despite its high incidence, because of similarities in presenting symptoms with other pathologic entities. The current case report describes a posttraumatic osteoid osteoma. Three years after osteosynthesis of a distal tibial fracture an osteoid osteoma was diagnosed at the former fracture site. After excluding osteomyelitis as a possible diagnosis, the tumor was excised successfully. Based on current knowledge of the pathogenesis of osteoid osteoma, it is unlikely that the lesion observed in the patient was attributable to the previous fracture.

Adolescent↗

PubMed2001

Ultrasound avoidance behaviour in the bushcricket Tettigonia viridissima (Orthoptera: Tettigoniidae).

The responses of female Tettigonia viridissima to simulated bat echolocation calls were examined during tethered flight. The insects responded with three distinct behaviours, which occurred at graded stimulus intensities. At low intensities (threshold 54 dB SPL), T. viridissima responded by steering away from the sound source (negative phonotaxis). At intensities approximately 10 dB higher, beating of the hindwing was interrupted, although the insect remained in the flight posture. A diving response (cessation of the wingbeat, closure of the forewings and alignment of the legs against the body) occurred with a threshold of 76 dB SPL. Considering these thresholds, we estimate that the diving response occurs at approximately the sound amplitude at which many aerial-hawking bats first receive echoes from the insect. The other behaviours probably occur before the bat detects the insect and should therefore be interpreted as early avoidance behaviours. The repertoire of startle responses in T. viridissima, with directional and non-directional components, is similar to those of crickets and moths, but quite different from those described for another bushcricket (Neoconocephalus ensiger), which shows only a non-directional response. This supports the conclusion that bat-evasive behaviours are not conserved within the Tettigoniidae, but instead are shaped by the ecological constraints of the insects.

Animals↗

PubMed2000

Function of the cytosolic N-terminus of sucrose transporter AtSUT2 in substrate affinity.

AtSUT2 was found to be a low-affinity sucrose transporter (K(M)=11.7 mM at pH 4). Chimeric proteins between AtSUT2 and the high-affinity StSUT1 were constructed in which the extended N-terminus and central loop of AtSUT2 were exchanged with those domains of StSUT1 and vice versa. Chimeras containing the N-terminus of AtSUT2 showed significantly lower affinity for sucrose compared to chimeras containing the N-terminus of StSUT1. The results indicate a significant function of the N-terminus but not the central cytoplasmic loop in determining substrate affinity. Expression of AtSUT2 in major veins of source leaves and in flowers is compatible with a role as a second low-affinity sucrose transporter or as a sucrose sensor.

Amino Acid Sequence↗