Platelet-activating factor acetylhydrolase 1B3 (PAFAH1B3) is required for the formation of the meiotic spindle during in vitro oocyte maturation

Platelet-activating factor (PAF) is a well-described autocrine growth factor involved in several reproductive processes and is tightly regulated by its hydrolysing enzyme, PAF acetylhydrolase 1B (PAFAH1B). This intracellular enzyme consists of three subunits: one regulatory, 1B1, and two catalytic, 1B2 and 1B3. PAFAH1B3 has remained uncharacterised until now. Here, we report that PAFAH1B3 is present during the different stages of the first meiotic division in bovine, murine and human oocytes. In these species, the PAFAH1B3 subunit was clearly present in the germinal vesicle, while at metaphase I and II, it localised primarily at the meiotic spindle structure. In cattle, manipulation of the microtubules of the spindle by nocodazole, taxol or cryopreservation revealed a close association with PAFAH1B3. On the other hand, disruption of the enzyme activity either by P11, a selective inhibitor of PAFAH1B3, or by PAFAH1B3 antibody microinjection, caused arrest at the MI stage with defective spindle morphology and consequent failure of first polar body extrusion. In conclusion, our results show that one of the catalytic subunits of PAFAH1B, namely PAFAH1B3, is present in bovine, murine and human oocytes and that it plays a functional role in spindle formation and meiotic progression during bovine oocyte maturation.

Intracellular localisation of platelet-activating factor during mammalian embryo development in vitro: a comparison of cattle, mouse and human

Platelet-activating factor (PAF) is a well-known marker for embryo quality and viability. For the first time, we describe an intracellular localisation of PAF in oocytes and embryos of cattle, mice and humans. We showed that PAF is represented in the nucleus, a signal that was lost upon nuclear envelope breakdown. This process was confirmed by treating the embryos with nocodazole, a spindle-disrupting agent that, as such, arrests the embryo in mitosis, and by microinjecting a PAF-specific antibody in bovine MII oocytes. The latter resulted in the absence of nuclear PAF in the pronuclei of the zygote and reduced further developmental potential. Previous research indicates that PAF is released and taken up from the culture medium by preimplantation embryos invitro, in which bovine serum albumin (BSA) serves as a crucial carrier molecule. In the present study we demonstrated that nuclear PAF does not originate from an extracellular source because embryos cultured in polyvinylpyrrolidone or BSA showed similar levels of PAF in their nuclei. Instead, our experiments indicate that cytosolic phospholipase A2 (cPLA2) is likely to be involved in the intracellular production of PAF, because treatment with arachidonyl trifluoromethyl ketone (AACOCF3), a specific cPLA2 inhibitor, clearly lowered PAF levels in the nuclei of bovine embryos.

Sepiapterin reductase deficiency in a 2-year-old girl with incomplete response to treatment during short-term follow-up

Sepiapterin reductase (SR) catalyses the last step in the tetrahydrobiopterin biosynthesis pathway; it converts 6-pyruvoyl-tetrahydropterin (6-PTP) to BH(4) in an NADPH-dependent reaction. SR deficiency is a very rare autosomal recessive disorder with normal phenylalanine (Phe) concentration in blood and diagnostic abnormalities are detected in CSF. We present a 16-month-old girl with SR deficiency. From the newborn period she presented with an adaptation regulatory disorder. At the age of 3 months, abnormal eye movements with dystonic signs and at 4.5 months psychomotor retardation were noticed. Since that time axial hypotonia with limb spasticity (or rather delayed reflex development), gastro-oesophageal reflux and fatigue at the end of the day has been observed. Brain MRI was normal; EEG was without epileptiform discharges. Analysis of biogenic amine metabolites in CSF at the age of 16 months showed very low HVA and 5-HIAA concentrations. Analysis of CSF pterins revealed strongly elevated dihydrobiopterin (BH(2)), slightly elevated neopterin and elevated sepiapterin levels. Plasma and CSF amino acids concentrations were normal. A phenylalanine loading test showed increased Phe after 1 h, 2 h and 4 h and very high Phe/Tyr ratios. SR deficiency was confirmed in fibroblasts and a novel homozygous g.1330C>G (p.N127K) SPR mutation was identified. On L-dopa and then additionally 5-hydroxytryptophan, the girl showed slow but remarkable progress in motor and intellectual ability. Now, at the age of 3 years, she is able to sit; expressive speech is delayed (to 1 1/2 years), passive speech is well developed. Her visual-motor skills, eye-hand coordination and social development correspond to the age of 2 1/2 years.

Restoration of the continuity of dog ureter after resection of its 5 cm middle segment

OBJECTIVE

To evaluate the restoration of the ureter of the dog after resection of a 5 cm-long middle segment.

MATERIALS AND METHODS

Eight dogs underwent resection of the middle segment of the ureter, after which a 6-8 F Bard ureteric stent modelling catheter was inserted into both remaining portions of the ureter for 3 months. One month after removal of the stent the animals were killed and their ureters examined both grossly and microscopically. Paraffin-embedded sections were subjected to microscopic and immunohistochemical studies.

RESULTS

The continuity of the ureter was restored but the reconstructed segment was narrowed to a variable extent. The wall of the ureter was lined by normal urothelium but consisted of fibrous connective tissue which failed to produce a regular coat. The reconstructed segment showed no smooth muscle cells (negative staining with azan and a negative reaction with monoclonal antibodies against desmin). A few smooth myocytes were found only at the border with intact portions of the ureter.

CONCLUSIONS

The surgical procedure resulted in the restoration of ureteric continuity by repair and not by regeneration of its wall.

Microwave-assisted staining of mucosal mast cells and granulated intra-epithelial lymphocytes after formalin fixation

Rat jejunum was fixed with either formalin or methanol-formalin acetic acid (MFAA) and stained with Astra Blue or Alcian Blue with or without microwave irradiation. Staining of both mucosal mast cells and granulated intra-epithelial lymphocytes after formalin fixation was considerably improved by microwave irradiation. On the other hand, microwave irradiation slightly impaired staining of mucosal mast cells (MMC) and even more strongly granulated intra-epithelial lymphocytes (GIEL) after MFAA fixation.

Detection of testicular neoplasms by cytological examination of seminal fluid

The technique for detection of neoplastic cells in the seminal fluid of patients with testicular malignancies is presented. This preliminary study of 7 patients with testicular tumors and 50 controls demonstrates the possibility of using cytological examination of the sperm as the screening method for testicular tumors.

Lamina propria macrophages of intestine of the guinea pig. Possible role in phagocytosis of migrating cells

The macrophages of lamina propria were commonly found both in the small and the large intestine of guinea pigs, mice, rats, and in human duodenum. The frequency of macrophage occurrence was highest in the lamina propria of villous apices of the small intestine and beneath the lining epithelium of the large intestine. In the cytoplasm of lamina propria macrophages localized in those regions, Feulgen-positive (DNA-containing) granules could be observed particularly in the guinea pig intestine. Autoradiography of the latter, 3 to 5 days after [3H]thymidine injection, showed the coincidence of occurrence of labeled Feulgen-positive granules in the macrophage cytoplasm with the appearance of labeled epithelial cells and sheath-fibroblasts in the region of lamina propria containing the highest accumulation of macrophages, i.e., at the apices of villi of the small intestine and beneath the lining epithelium of the large intestine. Labeled nuclei of macrophages were observed scarcely and much less frequently than were labeled cytoplasmic granules. No labeled Feulgen-positive granules could be seen in macrophages 1/2 hr, 1, 2, and 7 days after [3H]thymidine injection. It is suggested that the lamina propria macrophages may play a role in the phagocytosis of some migrating cells of the intestinal mucosa, most probably of the sheath-fibroblasts and/or intraepithelial lymphocytes.