Volume 118  ·   Issue 17  ·  2005

Background Cytogenetic and molecular studies of azoospermic and oligozoospermic males have suggested the presence of azoospermia factors (AZF) in the Y chromosome. Deletion in AZF regions has been reported to disrupt spermatogenesis and cause infertility. Several candidate genes responsible for spermatogenesis have been identified in this region and some of them are thought to be functional in human spermatogenesis. And we reported clinical and molecular studies of Y chromosome microdeletions in Chinese. This study aimed at assessing the frequency of microdeletions in Chinese men with idiopathic and nonidiopathic infertility problems and dicussing the clinical significance of the AZF region. Methods In this study, we screened 143 infertile men (62 with idiopathic infertilitas and 81 with nonidiopathic infertilitas), in whom karyotype, sperm count, hormonal parameters and fine needle aspiration cytology were evaluated. Genomic DNA was extracted from the peripheral leukocytes. Molecular analysis was performed by two multiplex polymerase chain reactions (PCR) using a set of a sequence tagged sites (STS) from 3 different regions of the Y chromosome: AZFa (sY84, sY86), AZFb (sY127, sY134), AZFc (sY254, sY255). Results Nineteen point four percent of idiopathic males (12/62, 19.4%) had microdeletions of either the AZFa, AZFb, AZFc or AZFb+c region. Significantly, a high frequency of microdeletions (9/81, 11.1%) was found in nonidiopathic patients with varicocele and cryptorchidism. No deletions were found in healthy fertile men. There were no significant differences in the localization and extent of deletions between idiopathic and nonidiopathic patients. Conclusions The knowledge of the presence of these deletions in idiopathic and nonidiopathic cases is important to understand the prognosis, better management and counsel these patients accordingly. Furthermore, a more extended screening for Y chromosome microdeletions in idiopathic and nonidiopathic men, particularly candidates for intracytoplasmic sperm injection, is recommended.

Background Melanotic schwannoma is a rare variant of schwannoma composed of melanin-producing cells with ultrastructural features of schwann cells. The description of the course of the tumors differs somewhat, but it is generally considered as a benign lesion. We investigated the clinicopathologic features, immunophenotypes, and ultrastructural features of 13 patients with nonpsammomatous melanotic schwannoma (NPMS). Methods Tumor specimens of each patient were sectioned and stained with hematoxylin-eosin, Fontana-Masson, Prussian blue, and periodic acid-Schiff (PAS). Immunohistochemical markers such as S-100, Leu-7, HMB-45, Melan-A, CK, EMA, vimentin, GFAP, laminin, collagen Ⅳ and MIB-1 were detected with the Envision immunohistochemical staining method. Four of the cases were observed by electron microscopy. Results Of the 13 patients, 8 were male and 5 female, aged from 11 to 92 years (mean, 38.6 years). The tumor sites included the spinal nerve root (5 patients), cranial nerve (1), greater omentum (1), subcutaneous tissue (3), mesentery (1), bone (1) and mediastinum (1). Eleven patients were followed up for over 2 years, with a mean of 5.9 years. One patient (9.1%) with a primary tumor in the greater omentum developed another primary tumor of the same type in the subcutaneous tissue of the abdominal wall after the first operation. Local recurrence of the tumor was seen in 2 patients (18.2%). One patient (9.1%) showed the local recurrence and metastasis. Seven patients (63.6%) showed no evidence of the recurrence or metastasis. Grossly, all tumors were well-circumscribed and the gross findings were suggestive of melanin-containing tumors. The tumor was composed of spindled and epithelioid cells with abundant intracytoplasmic melanin pigments. Nuclei were round and contained delicate, evenly distributed chromatins as well as small, distinct nucleoli. In some areas, the nucleoli were large and prominent. Rare mitoses were seen in most lesions except the larger omentum lesion. The pigment was shown to be positive for the Fontana-Masson and negative for Prussian blue and PAS. Immunohistochemical staining for S-100, Leu-7, HMB-45, Melan-A, and vimentin were strongly positive. Linear immunoreactions of both laminin　and collagen Ⅳ was detected in all patients. Ultrastructurally, numerous elongated tumor-cell processes, duplicated basement membrane and melanosomes were observed in all developmental stages. Conclusions Histologically, melanotic schwannoma is a rare variant of schwannoma composed of melanin-producing cells with ultrastructural features of schwann cells. Distinguishing between this tumor and malignant melanoma is of paramount importance in planning of management. Immunohistochemically, combined use of laminin and collagen Ⅳ is valuable in distinguishing melanotic schwannoma from malignant melanoma. Wide local resection and additional radiotherapy should be advocated. Further studies including cytogenetic or molecular biology are still required to better delineate melanotic schwannoma from malignant melanoma. Appropriate long-term follow-up is needed for all melanotic schwannomas.

Background It is essential to establish an animal model for the elucidation of the biological behaviors of stem cells in vivo. We constructed a chimeric animal model by in utero transplantation for investigation of stem cell transplantation. Methods This chimerism was achieved by injecting the stem cells derived from the bone marrow of green fluorescence protein (GFP)-transgenic mice into fetal mice at 13.5 days of gestation. Several methods such as polymerase chain reaction (PCR), real-time PCR, fluorescence-assisted cell sorting (FACS) and fluorescence in situ hybridization (FISH) were used for the observation of donor cells. Results Under a fluorescence microscope, we observed the GFP cells of donor-origin in a recipient. PCR, FACS analysis and FISH indicated chimerism at various intervals. Real-time PCR indicated that some donor cells existed in chimera for more than 6 months. Conclusions Allogenic stem cells may exist in recipients for a long time and this allogenic animal model provides a useful tool for studying the behavior of hematopoietic stem cells and also offers an effective model system for the study of stem cells.

Background Damage articular cartilage has very limited capacity for spontaneous healing. Tissue engineering provides a new hope for functional cartilage repair.Creation of an appropriate cell carrier is one of the critical steps for successful tissue engineering. With the suppoosition that a biomimetic construct might promise to generate better effects, we developed a novel composite scaffold and investigated its potential for cartilage tissue engineering. Methods Chitosan of 88% deacetylation was prepared via a modified base reaction procedure. A freeze-drying process was employed to fabricate a three-dimensional composite scaffold consisting of chitosan and type II collagen. The scaffold was treated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. Ultrastructure and tensile strength of the matrix were carried out to assess its physico-chemical properties. After subcutaneous implantation in rabbits, its in vivo biocompatibility and degradability of the scaffold were determined. Its capacity to sustain chondrocyte growth and biosynthesis was evaluated through cell-scaffold co-culture in vitro. Results The fabricated composite matrix was porous and sponge-like with interconnected pores measuring from 100-250 μm in diameter. After cross-linking, the scaffold displayed enhanced tensile strength. Subcutaneous implantation results indicated the composite matrix was biocompatible and biodegradable. In intro cell-scaffold culture showed the scaffold sustained chondrocyte proliferation and differentiation, and maintained the spheric chondrocytic phenotyoe. As indicated by immunohistochemical staining, the chondrocytes synthesized type II collagen. Conclusions Chitosan and type II collagen can be well blended and developed into a porous 3-D biomimetic matrix. Results of physico-chemical and biological tests suggest the composite matrix satisfies the constraints specified for a tissue-engineered construct and may be used as a chondrocyte carrier for cartilage tissue engineering.

Background Microcalcifications play a very important role in detection of breast cancer, especially early stage breast cancer. However, ambiguity still exists in understanding the relationship between radiological and pathological characteristics of microcalcifications. The definitive indication of a biopsy has not been established. The purpose of this study is to evaluate the relationship of classification of breast microcalcifications using full-field digital mammography to the pathological characteristics. Methods For all the women an open biopsy had been conducted. One hundred and three mammographs showing clustered microcalcifications from 98 consecutive patients were reviewed along with their pathological records. To investigate the value of each criterion for the detection of cancer, univariate and multivariate analyses were performed on the entire sample and then on morphological subgroups. Results Pathological examination showed 67 malignant lesions (65.05%) and 36 benign lesions (34.95%). In the univariate analysis, four radiological variables were significant: morphological type (P=0.001), complicated by a mass (P=0.002), number of microcalcifications per cluster (P=0.02) and linear or triangular distribution of clusters (P=0.009). In the multivariate analysis, two criteria remained significant: morphological type (P<0.001) and complicated by a mass (P=0.001). The percentage of malignancy was 37.0%, 60.0%, 78.8%, and 88.9%, respectively, for type 2 (regularly punctiform), type 3 (dusty), type 4 (irregularly punctiform) and type 5 (vermicular) microcalcifications (Le Gal’s classification). The malignancy was 78.6% for microcalcifications complicated by a mass and 48.9% without a mass. The difference was significant (P<0.05). The relationship between morphological types of microcalcifications and the pathological characteristics was also studied. In subgroups, type 3 (dusty) microcalcifications complicated by a mass (P=0.001) or with the number of microcalcifications more than 10 (P=0.024); and type 2 (regularly punctiform) with a diameter of the area over 20 mm (P=0.024) or complicated by a mass (P=0.025) were statistically significant as criteria for malignant tumour. Conclusions Most cases of microcalcifications of type 4 or 5; type 3 complicated by a mass or with the number of microcalcifications more than 10; type 2 complicated by a mass or with a diameter of the area over 20 mm; are indicative of cancer. Open biopsy is recommended to acquire definitive pathological diagnosis for these cases. For the remainder of the morphological types, stereotaxic biopsy or followup should be considered.

Background Nuclear factor κB (NF-κB) overactivation, requiring phosphorylation and degradation of its inhibitor IκBα, is the basis for chronicity of airway inflammation in asthma. Based on our previous plasmid pShuttle-IκBα, carrying an IκBα gene from human placenta, we optimized a novel IκBα mutant (IκBαM) gene, constructed and characterized its replication-deficient recombinant adenovirus (AdIκBαM), and tested whether AdIκBαM-mediated overexpression of IκBαM could inhibit the NF-κB activation in endothelial cells. Methods IκBαM gene (203-1003 bp) encoding 267 amino acids, acquired by site-directed deleting N-terminal phosphorylation sites of serine 32/36, was subcloned into the pShuttle and pGEM-T vectors for further polymerase chain reaction (PCR), restriction digestion, deoxyribonucleic acid (DNA) sequencing and homology analyses. Subsequent to inserting the expression unit of pShuttle-IκBαM, containing cytomegalovirus (CMV) promoter, IκBαM complementary DNA (cDNA) and polyadenylic acid (PolyA) signals, into the type 5 adenovirus (Ad5) vector, the resultant AdIκBαM was packaged in human embryonic kidney (HEK) 293 cells by cotransfection with lipofectamine. Western blot analysis and electrophoretic mobility shift assay were utilized to detect the AdIκBαM-mediated overexpression of IκBαM in HEK293 cells and its suppressive effect on phorbol 12-myristate 13-acetate (PMA)-induced NF-κB activation in human umbilical vein endothelial (ECV304) cells, respectively. Results The relevant nucleotides and deduced amino acids of 801 bp IκBαM gene were consistent with those of IκBα gene (GenBank accession number: M69043). The titer of the prepared AdIκBαM was 4.0×10(12) plaque-forming units (pfu)/L. Moreover, the IκBαM gene was overexpressed in HEK293 cells, and potently inhibited the PMA-induced NF-κB activation in ECV304 cells dose-dependently. Conclusions AdIκBαM is a novel vector for both efficient transfer and specific overexpression of IκBαM gene, as well as potent inhibition of NF-κB activity, providing a promising strategy for gene therapy of asthma.

Background Severe acute respiratory syndrome is frequently complicated by respiratory failure requiring ventilatory support. We aimed to compare the efficacy of non-invasive ventilation against invasive mechanical ventilation treating respiratory failure in this disease. Methods Retrospective analysis was conducted on all respiratory failure patients identified from the Hong Kong Hospital Authority Severe Acute Respiratory Syndrome Database. Intubation rate, mortality and secondary outcome of a hospital utilizing non-invasive ventilation under standard infection control conditions (NIV Hospital) were compared against 13 hospitals using solely invasive ventilation (IMV Hospitals). Multiple logistic regression analyses with adjustments for confounding variables were performed to test for association between outcomes and hospital groups. Results Both hospital groups had comparable demographics and clinical profiles, but NIV Hospital (42 patients) had higher lactate dehydrogenase ratio and worse radiographic score on admission and ribavirin-corticosteroid commencement. Compared to IMV Hospitals (451 patients), NIV Hospital had lower adjusted odds ratios for intubation (0.36, 95% CI 0.164-0.791, P=0.011) and death (0.235, 95% CI 0.077-0.716, P=0.011), and improved earlier after pulsed steroid rescue. There were no instances of transmission of severe acute respiratory syndrome among health care workers due to the use of non-invasive ventilation. Conclusion Compared to invasive mechanical ventilation, non-invasive ventilation as initial ventilatory support for acute respiratory failure in the presence of severe acute respiratory syndrome appeared to be associated with reduced intubation need and mortality.