Fatigue Crack Growth Characteristics and Fracture Toughness of γ-Tial Base Alloy Sheet Material

Room temperature tension-tension fatigue crack growth experiments were perfomed on single edge notch specimens of Ti-48Al-2Cr sheet materials produced on industrial scale with different microstructures ranging from near gamma to fully lamellar. Crack extension was monitored using a travelling optical microscope and a DC potential method. Crack paths and fracture surfaces were investigated by SEM. Fracture toughness data were determined by monotonic loading of previously fatigued samples.

Germ cell dynamics in the testis of the postnatal common marmoset monkey (Callithrix jacchus)

The seminiferous epithelium in the nonhuman primate Callithrix jacchus is similarly organized to man. This monkey has therefore been used as a preclinical model for spermatogenesis and testicular stem cell physiology. However, little is known about the developmental dynamics of germ cells in the postnatal primate testis. In this study, we analyzed testes of newborn, 8-week-old, and adult marmosets employing immunohistochemistry using pluripotent stem cell and germ cell markers DDX4 (VASA), POU5F1 (OCT3/4), and TFAP2C (AP-2γ). Stereological and morphometric techniques were applied for quantitative analysis of germ cell populations and testicular histological changes. Quantitative RT-PCR (qRT-PCR) of testicular mRNA was applied using 16 marker genes establishing the corresponding profiles during postnatal testicular development. Testis size increased during the first 8 weeks of life with the main driver being longitudinal outgrowth of seminiferous cords. The number of DDX4-positive cells per testis doubled between birth and 8 weeks of age whereas TFAP2C- and POU5F1-positive cells remained unchanged. This increase in DDX4-expressing cells indicates dynamic growth of the differentiated A-spermatogonial population. The presence of cells expressing POU5F1 and TFAP2C after 8 weeks reveals the persistence of less differentiated germ cells. The mRNA and protein profiles determined by qRT-PCR and western blot in newborn, 8-week-old, and adult marmosets corroborated the immunohistochemical findings. In conclusion, we demonstrated the presence of distinct spermatogonial subpopulations in the primate testis exhibiting different dynamics during early testicular development. Our study demonstrates the suitability of the marmoset testis as a model for human testicular development.

Krüppel-like factor 4 is widely expressed in the mouse male and female reproductive tract and responds as an immediate early gene to activation of the protein kinase A in TM4 Sertoli cells

Krüppel-like factor 4 (KLF4) is a zinc finger transcription factor critically involved in cell proliferation, differentiation, and carcinogenesis. Recently, KLF4 has also been used for the generation of induced pluripotent stem cells. In this study, we analyzed Klf4 expression in different mouse tissues using northern blot analysis and immunohistochemistry. Focusing on the male and female reproductive tract, we showed for the first time that KLF4 is expressed in the epithelia of the murine uterus and the vagina. In the male reproductive tract, we detected KLF4 in the epithelia of the epididymis, ductus deferens, coagulating gland, and the penis. As KLF4 is strongly inducible by FSH signaling in Sertoli cells and as this transcription factor is also involved in Sertoli cell development, we employed the mouse Sertoli cell line TM4 as a model system to investigate i) the induction kinetics of Klf4 upon activation of the cAMP/protein kinase A pathway by forskolin and ii) the effects of Klf4 induction on TM4 cell cycle progression. Interestingly, Klf4 mRNA and protein were rapidly but transiently induced, reaching peak levels after 90-120 min and declining to basal levels within 4 h. Compared with the inducible cAMP early repressor, an immediate early response gene, the induction kinetics of Klf4 is much faster. In conclusion, Klf4 is an immediate early gene in TM4 cells and its expression in several epithelia of the male and female reproductive tract suggests an important role of Klf4 in mouse reproductive functions.

The pluripotency transcription factor Krüppel-like factor 4 is strongly expressed in intratubular germ cell neoplasia unclassified and seminoma

Germ cell tumors of the testis are the most frequent tumors in men between 20 and 40 years. Their most common subtype is the seminoma, which arises like the embryonal carcinoma from an intratubular germ cell neoplasia unclassified (IGCNU), i.e. fetal germ cells that escaped from the control of the developing testicular stem cell niche, eventually leading to a fully developed seminoma (or embryonal carcinoma). The molecular causes for the development of an IGCNU are still unknown. However, IGCNU cells share the expression of several factors with primordial germ cells and gonocytes and, interestingly, also with pluripotent embryonic stem (ES) cells and induced pluripotent stem (iPS) cells. One factor playing important roles in both iPS and ES cells is the transcription factor Krüppel-like factor 4 (KLF4). This study examined KLF4 expression data from 179 human testicular samples including normal controls and seminoma, deposited in Gene Expression Omnibus repository for microarray data at the National Centre for Biotechnology Information. Immunohistochemistry was used to detect KLF4 protein expression in IGCNU (n = 6), seminoma (n = 14) and fetal human testes (n = 14). Microarray data from three independent sources suggest higher mRNA expression in seminoma than in normal testis. Normal spermatogonia, which are the stem cells of spermatogenesis, controlled by their stem cell niche, do not express KLF4. In contrast, IGCNU and seminoma cells strongly express KLF4. In conclusion, this finding suggests that KLF4 may be an important factor for the maintenance of the developmental and the tumorigenic potential of IGCNU as well as for the malignancy of seminoma.

Glycan stem-cell markers are specifically expressed by spermatogonia in the adult non-human primate testis

BACKGROUND

The glycan cell surface molecules, stage-specific embryonic antigen (SSEA)-1, -3 and -4 and tumor-rejection antigen (TRA)-1-60 and -1-81, are expressed in specific combinations by undifferentiated pluripotent cells, i.e. embryonic stem cells, induced pluripotent stem cells, embryonal carcinoma cells, primordial germ cells and embryonic germ cells. Upon differentiation of the cells, these markers vanish. Recently, it has been shown that also neonatal and adult mouse testes contain pluripotent cells. Here, we aimed at identifying in situ possibly pluripotent cells in the adult primate testis.

METHODS

Monoclonal antibodies raised against the glyco-epitopes SSEA-1, -3 and -4 and TRA-1-60 and -1-81, respectively, were tested to detect cells expressing the antigens, by immunohistochemistry on Bouin's-fixed and paraffin-embedded adult primate testes. Man, the new-world monkey, Callithrix jacchus (common marmoset), and the old-world monkey species, Macaca mulatta (Rhesus macaque) and Macaca silenus (Lion-tailed macaque), were included. The percentage of SSEA-4-positive cells in three adult marmoset testes was determined using flow cytometry.

RESULTS

Spermatogonia in the testes of C. jacchus were labeled by SSEA-4, TRA-1-60 and -1-81-antibodies. In the macaques, spermatogonia were detected by SSEA-4 and TRA-1-81-antibodies. TRA-1-61 did not bind to macaque spermatogonia. Also, SSEA-1 and -3 did not bind to spermatogonia in any species. In human testes, we never obtained any clear staining. The total percentage of SSEA-4-positive cells in marmoset testes was 8.6 +/- 1.61%.

CONCLUSIONS

SSEA-4 and TRA-1-81-antibodies may be very well suited for the identification and isolation of spermatogonia, and possibly also germline stem cells, in the non-human primate testis.

Gross-total resection of malignant gliomas in elderly patients: implications in survival

BACKGROUND

Malignant gliomas in elderly patients are frequently under represented in neuro-oncology trials because of presumed low tolerability of gross-total resection and radiochemotherapy treatments. Thus, the balance of benefit versus adverse response of standard glioma therapy remains controversial. We hypothesized that older patients with malignant gliomas might also take advantage of extensive surgical procedures.

PATIENTS AND METHODS

We analyzed retrospectively 138 consecutive malignant glioma patients. Sixty-two patients were >65 years whereas seventy-six were <or= 65 years. Evaluation consists of clinical features at diagnosis, neurological functional status, surgical procedures, post-operative complications and the predictive value of the former variables for survival.

RESULTS

At diagnosis, elderly patients showed a larger burden of comorbidities but they did not influence outcome significantly. Gross-total resection was associated with a longer survival as compared to biopsy and subtotal resection in both groups of elderly (P=0.05 and 0.001, respectively) and younger patients (P=0.004 and 0.003). Concerning complications, the only difference between both collectives was a higher incidence of psychosyndrome in the elderly group (P=0.016).

CONCLUSIONS

Our results indicate that gross-total resection of malignant gliomas in elderly patients is associated with a survival benefit without increased morbidity.

Influences of Extracellular Matrix and of Conditioned Media on Differentiation and Invasiveness of Trophoblast Stem Cells

Embryo implantation in the human and rodents relies on the trophoblast's ability to invade into the uterine stroma, partly depending on proteinases degrading components of basement membrane and underlying extracellular matrix (ECM). We have utilized mouse trophoblast stem (TS) cells (Science, 1998, 282:2072) to study trophoblast invasion and trophoblast-ECM interactions in vitro. On plastic in fibroblast-conditioned medium containing fibroblast growth factor (FGF)-4 and heparin, the cells remain proliferative but display increased differentiation in media without these components. Marker gene expression (Eomes, Pl-1, Tpbp) and invasion assays showed that TS cells exhibit increased invasive capacity when differentiating into giant cells and spongiotrophoblasts in unconditioned media without FGF-4 and heparin. Concomitantly, an up-regulation of matrix metalloproteinases (MMP)-9 and -14 was observed. Culture on gels of the basement membrane-like Matrigel resulted in striking changes in morphology and gene expression. Differentiating TS cells invaded into this ECM in a three-dimensional culture, while in turn ECM contact enhanced differentiation of TS cells and up-regulated the expression of MMP-9 and its tissue inhibitor (TIMP)-3. These findings implicate that the TS cell culture system used in this study can be utilized as a model for studying the regulation of trophoblast-ECM interactions, differentiation, and invasion in vitro.

[Management of congenital nasal fistulas and cysts]

BACKGROUND

Congenital nasal fistulas and cysts are uncommon craniofacial malformations. Mostly their symptoms appear already during childhood. In general, they are superficially located but they can reach the skull base or extend intracranially.

PATIENTS AND METHODS

Between 1979 and 2004 fifteen patients (11 children and 4 adults) with nasal fistulas and cysts were treated surgically at the ENT-Department of the Hospital Fulda gAG. In 7 patients (46.6 %) the skull base was involved. An intracranial intradural extension was found in 1 child and therefore needed a combined ENT and neurosurgical procedure. In the other 6 cases the nasal fistulas or cysts were located extradurally. They were resected by removing the Christa galli and strenghten the dura. An additional septorhinoplasty was carried out in 4 of the 15 patients. Within the follow-up period of up to 25 years no recurrences were observed.

CONCLUSIONS

The adequate therapy of nasal fistulas and cysts consists of complete resection. Magnetic resonance tomography (MRI) and computed tomography (CT) are essential to diagnose intracranial extension and to choose the proper surgical approach including a potential interdisciplinary procedure.

Karotisangiographie bei zentro-lateralen Schädelbasisfrakturen?

BACKGROUND

In latero-basal, central or spheno-fronto-orbital skull base fractures the internal carotid artery is more frequently involved in severe lesions than expected.

PATIENTS AND METHODS

Between 1996 and 2003 we examined 684 patients with Glasgow Coma Scales (GCS) between 2 and 15, median 7.2, using computed tomography (CT). In suspicion of a latero-basal, central or spheno-fronto-orbital fractur they got an additional high resolution skull base CT. If the bony canal of the internal carotid artery (ICA) was involved the patient underwent digital subtraction angiography (DSA). The ICA lesion was treated either interventional neuroradiologically, by surgery or only conservatively.

RESULTS

Of the 684 patients 33 (4.8 %) had fractures of the ICA bony canal and therefore underwent DSA. Among them were 25 men and 8 women (mean age 35.3 years). Lesions of the ICA were seen in 1.9 % of the patients. A traumatic cavernous-carotid fistula was found in 7 patients (1 %) and in 6 patients (0.9 %) a dissection and/or an aneurysm of the ICA was diagnosed. Six of the patients had clinical symptoms. The lesions were treated primarily interventional neuroradiologically (n = 5) as well as surgically in two cases by clipping the aneurysm and closing the sphenoid sinus, respectively.

CONCLUSIONS

Vessel lesions of the ICA in skull base fractures and involvement of the bony carotid canal are more frequent than mentioned in current literature. A solid diagnosis can only be achieved by DSA. Early diagnosis and treatment is important for improving the prognosis of these often multiply injured patients.