Immunohistochemical localization of substance P and substance P receptor (NK1) in the olivary pretectal nucleus of the rat

The olivary pretectal nucleus (OPN) is the first central nucleus in the pupillary light reflex arc (PLR). Substance P (SP) is a neuropeptide present in the OPN. The present immunohistochemical study, performed at the ultrastructural level, aimed to determine the synaptic localization of SP and SP receptor in the OPN. Three types of SP-positive terminals were found. The most abundant type was of retinal origin, characterized by electron-lucent mitochondria and round vesicles, organized in glomerular structures, making asymmetric synaptic contacts with dendrites, and profiles containing pleomorphic vesicles, also making synaptic contacts with dendrites. The second type of SP-immunoreactive terminal contained electron-dense mitochondria and pleomorphic vesicles. This type made symmetric synaptic contacts and may originate from the ventral part of the lateral geniculate nucleus. The third type of SP-immunoreactive terminals contained electron-dense mitochondria, clear round vesicles, and made an asymmetric synaptic contact. This type originates from the contralateral OPN. SP receptors of the NK1 subtype were revealed to be on dendrites and were part of the glomerular-like arrangement. On account of the present observations, it can be concluded that retinal projections to the OPN use SP as a neuromodulator and synapse on NK1 receptor-containing dendrites of large neurons projecting to the Edinger-Westphal nucleus. Since SP also modulates the parasympathetic component of the PLR, we postulate that SP plays a modulating role in all components of the PLR.     

Comparison of ultrasonographic findings in spontaneous abortions with normal and abnormal karyotypes

To determine whether ultrasonographic findings can predict the karyotype of spontaneous abortions, 137 pregnancies (54 spontaneous, 83 assisted ovulatory cycles) that subsequently aborted and had chromosome analysis performed on the products of conception were studied ultrasonographically. Transvaginal ultrasound was performed using an Acuson 128XP/10 with 7.5 MHz probe. The numbers of empty gestational sacs, small and normal for gestational size, embryonic poles and embryos with documented cardiac activity were calculated. The frequency of each of these findings in pregnancies with normal and abnormal karyotypes was compared. Of the 137 spontaneous abortions, 51 had normal chromosome analyses and 86 had abnormal karyotypes (68 aneuploidies and 18 polyploidies). Ultrasonographic findings in the 51 karyotypically normal pregnancies included 16 (31%) with empty gestational sacs, and 35 (69%) with embryonic poles, of which 24 (69%) were at least 1 week smaller than expected for gestational age and 11 (31%) were the expected size. Embryonic cardiac activity was documented in 22 (63%) of the 35 embryonic poles. Amongst 86 pregnancies with abnormal karyotypes, similar frequencies of ultrasound findings were found: 23 (27%) with empty gestational sacs, 42 (67%) with embryonic poles smaller than expected for gestational age, and 50 (79%) embryos lost after documentation of embryonic cardiac activity. No differences in the frequency of ultrasonographic findings of empty gestational sacs, small embryonic pole and embryonic cardiac activity were observed between karyotypically normal and abnormal spontaneous abortions. Ultrasonographic findings cannot predict the karyotype of spontaneous abortions.      

Gonadotrophin-releasing hormone agonist dose-dependency of pituitary desensitization during controlled ovarian hyperstimulation in IVF

The aim of this study was to find the minimal effective daily s.c. dose of the gonadotrophin-releasing hormone (GnRH) agonist, triptorelin acetate, that suppresses the GnRH-induced release of luteinizing hormone (LH) at time of human chorionic gonadotrophin (HCG) injection and thereby prevents spontaneous LH surges during in-vitro fertilization (IVF) stimulation cycles. Therefore, a double-blind, prospective and randomized titration study was performed. A total of 48 IVF patients were divided into four groups of 12 patients. Each group received a different dose of triptorelin acetate, namely 5, 15, 50 or 100 microg s.c. daily. Standard ovarian stimulation was carried out using urinary follicle stimulating hormone (FSH) preparations. A 500 microg GnRH test was performed 90 min before the HCG injection in order to measure the degree of pituitary desensitization. Spontaneous LH surges were not detected in any of the groups, although three patients in the 5 microg group had ovulated at the time of ovum retrieval. The pituitary LH response to the GnRH test at time of HCG, expressed as area under the curve (AUC), appeared to be dose-dependent. Thus, a daily s.c. dose of 100 microg triptorelin acetate appears to be too high, since adequate desensitization of the pituitary (i.e. no spontaneous LH surge) can be achieved with doses as low as 15 and 50 microg.      

Immunocytochemical localization of the glutamate transporter GLT-1 in goldfish (Carassius auratus) retina

Glutamate is the major excitatory neurotransmitter in the retina of vertebrates. Electrophysiological experiments in goldfish and salamander have shown that neuronal glutamate transporters play an important role in the clearance of glutamate from cone synaptic clefts. In this study, the localization of the glutamate transporter GLT-1 has been investigated immunocytochemically at the light and electron microscopical levels in the goldfish retina using a GLT-1-specific antibody. GLT immunoreactivity (IR) was observed at the light microscopical level in Müller cells, bipolar cells, the outer plexiform layer (OPL), and the inner plexiform layer (IPL). At the electron microscopical level, membrane-bound and cytoplasmic GLT-IR in the OPL was located in finger-like protrusions of the cone terminal located near the invaginating postsynaptic processes of bipolar and horizontal cells. GLT-IR was not observed in the vicinity of synaptic ribbons. This location of GLT-1 allows modulation of the glutamate concentration in the synaptic cleft, thereby shaping the dynamics of synaptic transmission between cones and second-order neurons. In the inner IPL, GLT-IR was observed in the cytoplasm and was membrane bound in mixed rod/cone bipolar cell terminals and cone bipolar cell terminals. The membrane-bound GLT-1 was generally observed at some distance from the synaptic ribbon. The morphology of the bipolar cell terminal together with the localization of GLT-1 suggests that at least these glutamate transporters are not primarily involved in rapid uptake of glutamate release by the bipolar cells. The GLT-IR in the cytoplasm of Müller cells was located throughout the entire goldfish retina from the outer limiting membrane to the inner limiting membrane. The location of GLT-1 in Müller cells is consistent with the role of Müller cells in converting glutamate to glutamine.     

Secondary infertility as a late complication of vesico-amniotic shunt therapy

OBJECTIVE: Vesico-amniotic shunting can be used for the treatment of fetal obstructive uropathy. However, the procedure is associated with a significant risk of complications. We report a case of a complicated vesico-amniotic placement, where a vesico-amniotic shunt ultimately resulted in, fortunately reversible, infertility. CASE: A 36-year-old multigravida was referred to our center at 13 weeks' gestation for the evaluation of fetal lower urinary obstruction. A vesico-amniotic shunt placement requiring several attempts was performed. A few weeks later premature rupture of the membranes occurred. At the request of the parents, the pregnancy was terminated at 22 weeks'gestation. The patient visited us again for secondary infertility, which turned out to be caused by a shunt left behind in the uterus, acting as an IUD. After hysteroscopic removal, she soon became pregnant again. CONCLUSION: This case illustrates the importance of careful documentation relating to each and every operation, of all materials used and what was retained in the patient. At delivery, obstetric staff should be completely aware of the prenatal treatment procedures performed, to ensure that no foreign objects are left by oversight, inside the patient's body.