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F Mayer

Publications and source records attributed to F Mayer.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cryptic diversity in European bats.

Different species of bat can be morphologically very similar. In order to estimate the amount of cryptic diversity among European bats we screened the intra- and interspecific genetic variation in 26 European vespertilionid bat species. We sequenced the DNA of subunit 1 of the mitochondrial protein NADH dehydrogenase (ND1) from several individuals of a species, which were sampled in a variety of geographical regions. A phylogeny based on the mitochondrial (mt) DNA data is in good agreement with the current classification in the family. Highly divergent mitochondrial lineages were found in two taxa, which differed in at least 11% of their ND1 sequence. The two mtDNA lineages in Plecotus austriacus correlated with the two subspecies Plecotus austriacus austriacus and Plecotus austriacus kolombatovici. The two mtDNA lineages in Myotis mystacinus were partitioned among two morphotypes. The evidence for two new bat species within Europe is discussed. Convergent adaptive evolution might have contributed to the morphological similarity among distantly related species if they occupy similar ecological niches. Closely related species may differ in their ecology but not necessarily in their morphology. On the other hand, two morphologically clearly different species (Eptesicus serotinus and Eptesicus nilssonii) were found to be genetically very similar. Neither morphological nor mitochondrial DNA sequence analysis alone can be guaranteed to identify species.

Animals↗
PubMed2001

Clinical impact of germ cell tumor cells in apheresis products of patients receiving high-dose chemotherapy.

PURPOSE: High-dose chemotherapy (HD-Ctx) followed by autologous peripheral-blood stem-cell (PBSC) transplantation is currently investigated in patients with poor prognosis or relapsed metastatic germ cell tumor (GCTs). This study analyzed the presence and the clinical importance of contaminating tumor cells in PBSC preparations used to support HD-Ctx in GCT patients. PATIENTS AND METHODS: Seven targets for reverse transcription polymerase chain reaction (RT-PCR)-based detection of GCT cells were able to detect seminomatous and different histologic variants of nonseminomatous tumor cells. PBSC preparations from 57 patients were investigated for the presence of contaminating tumor cells using this set of targets, including beta human chorionic gonadotropin (beta-hCG), fibronectin (EDB variant), epidermal growth factor receptor (EGFR), CD44 (v8 to 10 variant), germ cell and placental alkaline phosphatase (AP), human endogenous retrovirus type K (ENV and GAG), and XIST. Samples of PBSC preparations from four healthy donors for allogenic transplantations as well as blood specimens from 10 healthy volunteers served as negative controls. RESULTS: Fifty patients (43 first-line and seven second-line Ctx) were assessable. Combining all RT-PCR results, 29 PBSC preparations (58%) were positive for tumor-specific amplification products (HERV-K 0, fibronectin 4, XIST 14, beta-hCG 19, AP 19, CD44 24, EGFR 26). Ten (35%) of 29 patients who underwent transplantation with positive PBSC preparations and seven (33%) of 21 patients with negative PBSC preparations have suffered relapse or progression (not significant [ns]). With a median follow-up of 22 months (2 to 66) post-HD-Ctx projected 3-year survival rates are 68% (RT-PCR+) and 58% (RT-PCR-) (ns). None of the 10 control peripheral-blood samples showed positivity for any of the targets studied. CONCLUSION: GCT cells can be detected in more than 50% of PBSC preparations using a RT-PCR approach with multiple targets. Despite the presence of tumor cells, retransplantation of the PBSC products did not effect long-term outcome. Factors such as responsiveness to chemotherapy and tumor mass seem to overcome the importance of potentially re-infused tumor cells.

Adolescent↗
PubMed2001

Molecular systematics of bats of the genus Myotis (Vespertilionidae) suggests deterministic ecomorphological convergences.

Based on extensive phenetic analyses, bats of the genus Myotis have been classically subdivided into four major subgenera each of which comprise many species with similar morphological and ecological adaptations. Each subgenus thus corresponds to a distinct "ecomorph" encompassing bat species exploiting their environment in a similar fashion. As three of these subgenera are cosmopolitan, regional species assemblages of Myotis usually include sympatric representatives of each ecomorph. If species within these ecomorphs are monophyletic, such assemblages would suggest extensive secondary dispersal across geographic areas. Conversely, these ecomorphological adaptations may have evolved independently through deterministic processes, such as adaptive radiation. In this case, phylogenetic reconstructions are not expected to sort species of the same ecomorph into monophyletic clades. To test these predictions, we reconstructed the phylogenetic history of 13 American, 11 Palaearctic, and 6 other Myotis species, using sequence data obtained from nearly 2 kb of mitochondrial genes (cytochrome b and nd1). Separate or combined analyses of these sequences clearly demonstrate the existence of several pairs of morphologically very similar species (i.e., sibling species) which are phylogenetically not closely related. None of the three tested subgenera constitute monophyletic units. For instance, Nearctic and Neotropical species currently classified into the three subgenera were clustered in a single, well-supported monophyletic clade. These species thus evolved independently of their ecological equivalents from the Palaearctic region. Independent adaptive radiations among species of the genus Myotis therefore produced strikingly similar evolutionary solutions in different parts of the world. Furthermore, all phylogenetic reconstructions based on mtDNA strongly supported the existence of an unsuspected monophyletic clade which included all assayed New World species plus M. brandtii (from the Palaearctic Region). This "American" clade thus radiated into a morphologically diverse species assemblage which evolved after the first Myotis species colonized the Americas. Molecular reconstructions support paleontological evidence that species of the genus Myotis had a burst of diversification during the late Miocene-early Pliocene epoch.

Animals↗
PubMed2001

Cryptic mammalian species: a new species of whiskered bat (Myotis alcathoe n. sp.) in Europe.

The analysis of morphological, behavioural and genetic characters of whiskered bats revealed a new European bat species within the family Vespertilionidae. We describe the morphology, karyology, genetic similarity, ecology and distribution of Myotis alcathoe n. sp. It closely resembles Myotis mystacinus, Myotis brandtii and Myotis ikonnikovi in morphology, but all four species show clear genetic differences in two mitochondrial genes (ND1 and 12S rRNA). Myotis alcathoe n. sp. is the smallest species among the European whiskered bats and uses the highest-frequency echolocation calls of all the European Myotis species. It prefers to hunt in small valleys with deciduous trees and flowing water, which is an endangered habitat. Records from Greece and Hungary indicate a distribution range in south-eastern Europe.

Animals↗
PubMed2001

Treatment of patients with metastatic germ cell tumors relapsing after high-dose chemotherapy.

With the use of cisplatin-based combination chemotherapy, metastatic testicular germ cell tumors can be cured in 70-80% of patients. Patients refractory to cisplatin-based chemotherapy have a very poor prognosis. Several mechanisms have been discussed for the development of platinum resistance such as a decreased intracellular concentration of the drug, increased repair of the drug induced damage, or an altered apoptotic response to this damage. Various chemotherapeutic agents have been evaluated in intensively pretreated or cisplatin-refractory patients. Neither the antracyclines nor vinorelbine, bendamustine, topotecan, nor biological agents such as suramin and retinoic acid have demonstrated clinical activity. Paclitaxel has been evaluated at different doses and schedules and yielded a response rate of 21% (range 11-30%) with individual patients achieving complete remissions. This has led to the inclusion of paclitaxel in salvage regimens in combination with cisplatin and/or ifosfamide. Two recent studies have evaluated gemcitabine in refractory germ cell tumors, demonstrating a response rate of 17% (95% CI: 7-28%) in 52 intensively pretreated patients, two-thirds of whom had relapsed after previous high-dose chemotherapy plus autologous stem cell transplantation. The nonhematologic toxicity of weekly gemcitabine at doses of 1000-1250 mg/m2 was tolerable and hematologic side effects included thrombocytopenia in approximately 20% of patients. Ongoing studies in refractory germ cell tumors performed by the German Testicular Cancer Study Group (GTCSG) are evaluating oxaliplatin, a platinum derivative with incomplete cross-resistance to cisplatin. Future trials combining new active agents may make it possible to test the use of alternating treatment strategies in patients with "poor prognostic" disease or as salvage treatment. It is hoped that the increase in knowledge of the molecular mechanism of testicular cancer may lead to the development of new therapeutic options.

Antineoplastic Agents↗
PubMed2001

Gain in strength and muscular balance after balance training.

The isolated effect of balance training on muscle strength of the flexors and extensors of the knee, without accompanying strength training, has not been addressed in the past. Effects of a balance training program alone were compared to a strength training program. Balance and strength training were performed by 15 persons each for 6 weeks including 12 training units of 25 min. Balance training was performed on instability training devices such as rolling board, mini trampoline and large rubber ball. The 15 persons of the strength training group trained on machines for leg curls and on leg presses for 25 min per unit. Measurements for balance were performed with one-leg balance on a narrow edge and a tilting stabilometer for 30 s; maximum isometric strength was measured using an isokinetic device for each leg separately. The muscular balance between dominant and non-dominant leg was calculated. Strength gain was similar for the flexors and extensors in both groups. One-leg balance improved after balance training (P< 0.01) with a 100% increase over the strength training group (P < 0.05) and the stabilometer test for each person in the balance (P < 0.01), but not in the strength training group. In the balance group the initial difference between right and left diminished. The results indicate balance training to be effective for gain in muscular strength, and secondly, in contrast to strength training, equalisation of muscular imbalances may be achieved after balance training.

Adult↗
PubMed2001

Metabolic reaction after concentric and eccentric endurance-exercise of the knee and ankle.

PURPOSE: Power training plays an essential part in many sport disciplines. The importance of eccentric power training remains a matter of controversial discussion. The objective of this study was therefore to investigate the difference in metabolic reaction between eccentric and concentric stress in comparable work. METHODS: Sixty-four men between 22 and 60 yr of age performed maximum isokinetic 1-min endurance tests of the knee and ankle each in concentric (180 degrees.s-1) and eccentric (60 degrees.s-1) modes with comparable total area of contraction-time curve (NS). Higher strength values (mean peak torque, P < 0.01), lower fatigue (fatigue index, P < 0.001), lower increase in lactate (P < 0.01), and lower ammonia production (P < 0.01) were found in eccentric than in concentric exercise, independent of the joint. The eccentric form of stress showed lower decrease and thus age-dependence in maximum strength and in fatigue than the concentric form. RESULTS: The results permit the conclusion that eccentric exercise leads to less fatigue and lower lactate and ammonia reaction than concentric exercise in comparable work levels. Variable visco-elastic properties of the muscle fibers themselves with additive passive strength in eccentric mode is considered as the cause. CONCLUSIONS: It remains uncertain whether the lower metabolic stress might be useful during the training process. A greater scope of training and increased number of training stimuli might be applied in primarily eccentric forms of exercise.

Adaptation, Physiological↗
PubMed2001

Reciprocal strength ratio in shoulder abduction/adduction in sports and daily living.

PURPOSE: Functionally, the shoulder is considered a ball joint, whereby high mobility is attended by low stability. Therefore, muscular balance is decisive for stability. Altered strength ratios are frequently described as "muscular dysbalances" and considered one of the causes of shoulder pathologies, whereby objective quantification is difficult. METHODS: In order to quantify physiological muscle balance, the strength ratio of shoulder abduction/adduction (AB/AD) was determined in 166 untrained men (UM) concentrically at 60 degrees.s-1 (LIDO-Active). The influence on this norm of one-sided (25 high-performance (TPH), 18 leisure tennis players (TPL)) and two-sided athletic exercise (32 gymnasts (GY)), altered daily exercise (11 paraplegics with paralysis time < 4 months (PP), 11 paraplegics with paralysis time > 2 yr (PU)), and a combination of altered daily exercise and athletic activity (16 trained paraplegics (PT)) was examined (ANOVA, alpha = 0.05). RESULTS: Determination of the AB/AD quotient in UM was 0.82. Shoulder stress in sports led to a decrease in quotients compared with UM because of a relatively increased torque in AD (P < 0.01). At the beginning of a paraplegia, the quotient of AB/AD is elevated (P < 0.05). This altered ratio decreases with duration of paralysis (PU) and athletic activity (PT). CONCLUSION: With increased shoulder stress, the altered strength ratios reflect specific requirements of the performance attained. However, the importance of muscular dysbalances for the onset of shoulder complaints must be considered more important than their influence on athletic performance capacity.

Activities of Daily Living↗
PubMed2001

Defining the mycoplasma 'cytoskeleton': the protein composition of the Triton X-100 insoluble fraction of the bacterium Mycoplasma pneumoniae determined by 2-D gel electrophoresis and mass spectrometry.

After treating Mycoplasma pneumoniae cells with the nonionic detergent Triton X-100, an undefined, structured protein complex remains that is called the 'Triton X-100 insoluble fraction' or 'Triton shell'. By analogy with eukaryotic cells and supported by ultrastructural analyses it is supposed that this fraction contains the components of a bacterial cytoskeleton-like structure. In this study, the composition of the Triton X-100 insoluble fraction was defined by electron microscopic screening for possible structural elements, and by two-dimensional (2-D) gel electrophoresis and MS to identify the proteins present. Silver staining of 2-D gels revealed about 100 protein spots. By staining with colloidal Coomassie blue, about 50 protein spots were visualized, of which 41 were identified by determining the mass and partial sequence of tryptic peptides of individual proteins. The identified proteins belonged to several functional categories, mainly energy metabolism, translation and heat-shock response. In addition, lipoproteins were found and most of the proteins involved in cytadherence that were previously shown to be components of the Triton X-100 insoluble fraction. There were also 11 functionally unassigned proteins. Based on sequence-derived predictions, some of these might be potential candidates for structural components. Quantitatively, the most prevalent proteins were the heat-shock protein DnaK, elongation factor Tu and subunits alpha and beta of the pyruvate dehydrogenase complex (PdhA, PdhB), but definite conclusions regarding the composition of the observed structures can only be drawn after specific proteins are assigned to them, for example by immunocytochemistry.

Bacterial Proteins↗
PubMed2001

Cloning and expression of a Ralstonia eutropha HF39 gene mediating indigo formation in Escherichia coli.

On complex medium Escherichia coli strains carrying hybrid plasmid pBEC/EE:11.0, pSKBEC/BE:9.0, pSKBEC/PP:3.3, or pSKBEC/PP:2.4 harboring genomic DNA of Ralstonia eutropha HF39 produced a blue pigment characterized as indigo by several chemical and spectroscopic methods. A 1,251-bp open reading frame (bec) was cloned and sequenced. The deduced amino acid sequence of bec showed only weak similarities to short-chain acyl-coenzyme A dehydrogenases, and the gene product catalyzed formation of indoxyl, a reactive preliminary stage for production of indigo.

Amino Acid Sequence↗
PubMed2001

First-pass effect of an intravenous bolus of [13C]bicarbonate displayed breath-by-breath.

The dilution of an intravenous bolus dose of [13C]bicarbonate is used as an estimate for the metabolic rate under certain conditions. It is a consistent finding in all studies that the total amount of intravenous [13C]bicarbonate cannot be recovered as breath 13CO2. In this study, we used a breath-by-breath analysis of 13CO2 to depict the washout of 13CO2 at a high temporal resolution to analyze the extent to which a probable first-pass effect is responsible for the reduced recovery. Eight healthy men were tested at seated rest and with bicycle exercise at a constant load relative to 40 and 75% maximal O2 consumption VO2 max). [13C]bicarbonate (0.0125 g/kg body wt) was administered as an intravenous bolus in each test. Respiratory mass spectrometry was used to derive the course of the end-tidal 13CO2-to-12CO2 ratio from the breath-by-breath data. Approximately 2 min after 13C administration, the washout curve could be fitted well by a two-exponential curve describing a two-compartment mammillary model. Immediately after administration of the bolus dose, an excess peak in the end-tidal 13CO2-to-12CO2 ratio appeared. This peak could not be included in the two-exponential fitting. The area under the first peak resulted in 3.8 +/- 1.3% of the total [13C]bicarbonate dose at rest, 11.5 +/- 2.9% at moderate exercise (40% VO2 max), and 16.9 +/- 4.0% at intensive exercise (75% VO2 max). The first-pass effect had an increasing impact of up to about two-thirds of the lacking bicarbonate with higher exercise intensity. The "loss" of tracer via this first-pass effect must be considered when the results of studies with parenteral administration of [13C]bicarbonate are considered, especially when it is given as a bolus dose and during exercise.

Adult↗
PubMed2000

High-dose platinum versus standard dose in advanced ovarian carcinoma: a randomized trial from the Gynecologic Cooperative Group of the French Comprehensive Cancer Centers (FNCLCC).

OBJECTIVE: The aim of this study was to evaluate the impact of platinum dose intensity on pathological response rate and overall survival in patients with advanced ovarian adenocarcinoma. METHODS: Between February 1992 and December 1996, 195 previously untreated patients with FIGO stage IIb-c, IIIb-c, or IV with macroscopic residual disease after suboptimal debulking surgery were randomized to receive CCC (100 mg/m(2) of cisplatin, 300 mg/m(2) of cyclophosphamide, 300 mg/m(2) of carboplatin, n = 96) or CC (100 mg/m(2) of cisplatin, 600 mg/m(2) of cyclophosphamide, n = 99) for six courses at 28-day intervals. A second-look laparotomy was planned at the end of chemotherapy. RESULTS: In the CCC arm, the platinum compound received dose intensity and relative total dose were 85 and 76%; in the CC arm, they were 94 and 85%. Grade 3-4 toxicity was more frequent in the CCC arm than in the CC arm for leukopenia (56% vs 26%, P < 0.001), febrile neutropenia (18% vs 4%, P = 0.002), anemia (31% vs 5%, P < 0.001), thrombopenia (55% vs 4%, P < 0.001), and ototoxicity (8% vs 0%, P < 0.001). The pathologic complete response rate was 22 and 14% in the CCC and CC arms, respectively (P = 0.19). With a median follow-up of 53 months, the median time to failure and the 3-year treatment failure-free survival rate were 17.4 months and 22% vs 13 months and 11% in the two arms, respectively (P = 0.01). The median survival time and the 3-year overall survival rate were, respectively, 30 months and 42% vs 25 months and 33% (P < 0.20). CONCLUSION: The platinum dose intensification (1.6-fold increase) obtained with the CCC association improves the treatment failure-free survival without significant impact on overall survival when compared with the CC regimen in suboptimal debulked ovarian adenocarcinoma. However, because of its high rate of hematologic toxicity and ototoxicity, this association cannot be recommended for routine practice.

Adenocarcinoma↗
PubMed2000

[Functional results after suture repair in ruptures of the long biceps tendon with special consideration of subacromial impingement].

Operative treatment for ruptures of the long biceps tendon still is discussed controversially. In the present literature the keyhole-technique is recommended according to favourable biomechanical conditions. In recent years refixation to the short biceps tendon was preferred. Now it is supposed that this technique may provoke subacromial impingement considering the loss of depression function of the long biceps tendon to the humeral head. Between 1980 to 1991 83 patients with rupture of the long biceps tendon were treated operatively by refixation to the short head. 28 patients were investigated after an average follow-up of 6.5 years. Due to the criteria of the Constant-Score 85% of patients achieved very good, 15% good results. At our patients provocation of a subacromial impingement could not be observed. The subacromial space was not reduced in the postoperative x-ray control. Compared with the non-operated shoulder isokinetic determination of isometric maximal peak torque for elbow-flexion, shoulder-abduction and shoulder-flexion yield to almost identical results for the operated shoulder. Refixation to the short head can be advised for treatment of ruptures of the long biceps tendon due to the certain technique with a low complication rate and very good functional outcome.

Adult↗
PubMed2000

[Individual isokinetic strength training in patients with gonarthrosis].

PROBLEM: To date, therapy of osteoarthritis of the knee is aimed at relieving pain and changing behavior patterns, which usually leads to reduced activity. The weakening of the quadricep's musculature leads to an increase in both joint instability and arthritis. Walking time is prolonged and the pain-induced reaction of knee angle velocity is onset by increased stress on other joints. The progressive muscle atrophy correlates to the degree of pain. The aim of this study was to demonstrate an improvement in strength and pain based on 4-week isokinetic strength training in gonarthritis patients. METHOD: During a conservative hospitalization period, isokinetic strength training was performed by 19 randomized patients with gonarthritis in addition to regular physiotherapy. Another 19 patients functioned as a control group. The work was examined at 60 degrees/s and 180 degrees/s and rated using a pain questionnaire at the start and end of the investigation. RESULTS: In addition to the expected increase of strength and strength endurance in the test group, the degree of pain could also be statistically significantly decreased compared to the control group. Activities of daily living, such as climbing stairs and standing-up, were also performed more easily. CONCLUSIONS: The therapeutic strategy for patients with osteoarthritis of the knee should be reconsidered to include less expensive therapeutic sport measures. Anglo-american and Scandinavian studies support this statement. Overuse and pain can be avoided by precise and low-dose strength training. Objective and reproducible measurements in the patients are essential to make individual training possible.

Adult↗
PubMed2000

Laparoscopic cholecystectomy and interventional endoscopy for gallstone complications during pregnancy.

BACKGROUND: Symptomatic or complicated gallstone disease is the most common reason for nongynecological operations during pregnancy. Gallstones are present in 12% of all pregnancies, and more than one-third of patients fail medical treatment and therefore require surgical endoscopy or laparoscopy. Gallstone pancreatitis and jaundice during pregnancy is associated with a high recurrence rate, exposing both fetus and mother to an increased risk of morbidity and mortality. METHODS: During a 4-year period, all pregnant patients (n = 37) with symptomatic or complicated gallstone disease were studied prospectively at the Landeskrankenhaus in Salzburg, Austria. Five patients had an endoscopic retrograde cholangiopancreatogram (ERCP) for biliary pancreatitis or jaundice; two of these underwent subsequent laparoscopic cholecystectomy. Another seven patients required laparoscopic cholecystectomy for severe pain or cholecystitis; all were in their 13th-32nd gestational week. Access was established by Veress needle in all cases. Insufflation pressure was 8-10 mm Hg, and mean operative time was 62 min. RESULTS: All patients delivered full-term, healthy babies. There were no postendoscopic or postoperative complications. All patients enjoyed full relief from their symptoms; there were no recurrences of pancreatitis or jaundice. CONCLUSIONS: The combination of ERCP and laparoscopic cholecystectomy offers a safe and effective option for the definitive treatment of complicated gallstone disease and intractable pain during pregnancy, and there is sufficient access for the combined treatment to be employed.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed2000

Identification of prognostic subgroups among patients with metastatic 'IGCCCG poor-prognosis' germ-cell cancer: an explorative analysis using cart modeling.

OBJECTIVES: The IGCCCG classification has identified three prognostic groups of patients with metastatic germ-cell tumors. 'Poor prognosis' is based on primary tumor localization, the presence of visceral metastases, and/or high tumor-marker levels. The overall survival rate of these patients is about 45%-55%. The present analysis attempts to identify subsets of patients with a more or less favorable outcome among the 'poor-prognosis' group. PATIENTS AND METHODS: We retrospectively explored prognostic subgroups in 332 patients with 'IGCCCG' poor-risk GCT using the classification-and-regression-tree model (CART). The following variables were included: primary tumor localization, presence of visceral or lung metastases, presence of an abdominal tumor, number of metastatic sites, serum levels of beta-HCG, AFP and LDH. All patients had been treated with cisplatin-etoposide-based chemotherapy within controlled clinical trials between 1984 and 1997. RESULTS PATIENT CHARACTERISTICS: gonadal/retroperitoneal (G/R) primary tumor 260 patients (78%), mediastinal primary tumor 72 patients (22%), visceral metastases 205 patients (62%) including 33 patients with CNS metastases, lung metastases 247 patients (74%), abdominal tumor 241 patients (72%), elevated AFP, beta-HCG or LDH levels 235 (71%), 253 (76%) and 275 (83%) of patients, respectively. Patients with primary mediastinal disease plus lung metastases exhibited the worst two-year PFS (28%), whereas patients with a primary G/R tumor and without visceral metastases showed the highest chance of two-year PFS (75%). The latter group of patients without visceral metastases and with a primary G/R tumor also had the most favourable two-year OS (84%). In contrast, patients with a primary mediastinal tumor and visceral metastases displayed the worst two-year OS (49%). CONCLUSIONS: Different prognostic subsets of patients can be identified among the group of 'poor-prognosis' GCT patients. The CART analysis model results in a hierarchy of prognostic factors which may allow to more precisely estimate the individual patient's prognosis. Identifying subgroups of 'very poor-prognosis' among 'poor-prognosis' patients may allow to test for new treatment strategies in selected subgroups.

Adolescent↗
PubMed2000

Escherichia coli-induced alterations of human spermatozoa. An electron microscopy analysis.

This study evaluated if the negative influence of Escherichia coli on the motility of human spermatozoa is a consequence of E. coli-induced ultrastructural alterations. Suspensions of spermatozoa were artificially infected with E. coli from a serotyped, pathogenic strain and incubated at 37 degrees C for 6 h. After incubation, spermatozoa were fixed in glutaraldehyde, stained with osmium tetroxide and ruthenium red and embedded in Spurr(R)-resin followed by ultramicrotomy. The sections were analysed subsequently by use of transmission electron microscopy. Uninfected suspensions of spermatozoa in medium and bacterial suspensions served as controls. Negative contrast technique was performed to facilitate visualization of ultrastructural details of the bacterial capsule after experimental exposure to spermatozoa. Electron microscopic evaluation revealed multiple and profound alterations in the ultrastructure of spermatozoa such as membrane defects and cytoplasmic vacuoles exclusively in spermatozoa of infected samples (> 90%). Morphological alterations involved all superficial structures of spermatozoa, in particular the plasma membrane of the mid-piece and neck as well as the inner and outer acrosomal membrane of the acrosome, indicating that morphological defects account for the immobilization of spermatozoa by E. coli. The results suggest that E. coli infection of ejaculates results in immobilization and impaired acrosomal function in human spermatozoa, findings that support the indication for antimicrobial chemotherapy in symptomatic and silent infections that affect the ejaculate.

Escherichia coli↗