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.     

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.     

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.     

PROP sensitivity affects macronutrient selection

The objective was to study the effect of 6-n-propylthiouracyl (PROP) taster status on macronutrient selection. Thirteen PROP nontasters (PNT) and 23 PROP tasters (PT) were offered three ad libitum lunches in a random order: a high-fat (HF; CHO/P/F: 30/10/60), a high-carbohydrate (HCHO; 80/10/10), and a mixed (MIX) lunch consisting of products of the HF and HCHO lunch. PT compared to PNT ate relatively more fat (47+/-9 vs. 38+/-10%, P<.05) and less carbohydrate (45+/-9 vs. 53+/-10%, P<.05) from the MIX lunch. When dividing PT into supertasters (PST) and medium tasters (PMT), the same relation between PT status and macronutrient selection was observed (P<.05). The energy density of the food consumed was higher for PT than for PNT (P<.05). Protein, food (g) and energy (kJ) intake, appetite, and hedonic value were not different between PT and PNT. At the HCHO as well as HF lunch, no differences with respect to macronutrient selection, food and energy intake, appetite levels, and hedonic value between PT and PNT were observed. However, at the HF lunch, energy density of the food consumed was higher for PT than for PNT, but this effect was not observed during the HCHO lunch. Hunger and satiety scores did not differ between PT and PNT. The hedonic value was higher for the MIX lunch compared to the HCHO and HF lunch for PT as well as for PNT.In conclusion, PT ingest more of the HF foods than of the HCHO foods from a mixed lunch compared to PNT.     

Calcium and Vitamin D in Sarcoidosis: Is Supplementation Safe?

Granulomas in sarcoidosis express high levels of 1α‐hydroxylase, an enzyme that catalyzes the hydroxylation of 25‐OH vitamin D to its active form, 1,25(OH)₂ vitamin D. Overproduction of 1α‐hydroxylase is held responsible for the development of hypercalcemia in sarcoidosis patients. Corticosteroids are used as first‐line treatment in organ‐threatening sarcoidosis. In this light, osteoporosis prevention with calcium and vitamin D (CAD) supplementation is often warranted. However, sarcoidosis patients are at risk for hypercalcemia, and CAD supplementation affects the calcium metabolism. We studied calcium and vitamin D disorders in a large cohort of sarcoidosis patients and investigated if CAD supplementation is safe. Retrospectively, data of 301 sarcoidosis patients from July 1986 to June 2009 were analyzed for serum calcium, 25‐hydroxy vitamin D (25‐(OH)D), 1,25‐dihydroxy vitamin D (1,25(OH)₂D), and use of CAD supplementation. Disease activity of sarcoidosis was compared with serum levels of vitamin D. Hypercalcemia occurred in 8%. A significant negative correlation was found between 25‐(OH)D and disease activity of sarcoidosis measured by somatostatin receptor scintigraphy. In our study, 5 of the 104 CAD‐supplemented patients developed hypercalcemia, but CAD supplementation was not the cause of hypercalcemia. Patients without CAD supplementation were at higher risk for developing hypercalcemia. During CAD supplementation, no hypercalcemia developed as a result of supplementation. Hypovitaminosis D seems to be related with more disease activity of sarcoidosis and, therefore, could be a potential risk factor for disease activity of sarcoidosis. Thus, vitamin D–deficient sarcoidosis patients should be supplemented. © 2014 American Society for Bone and Mineral Research.     

Neuronal substrates of gaze following in monkeys

Human and non-human primates follow the gaze of their respective conspecific to identify objects of common interest. Whereas humans rely on eye-gaze for such purposes, monkeys preferentially use head-gaze information. Functional magnetic resonance imaging (fMRI) studies have delineated an area in the human superior temporal sulcus (STS), which is specifically activated when subjects actively follow the eye-gaze of others. Similarly, using fMRI, we have identified an analogous region in the monkey's middle STS responding to gaze following. Hence, although humans and monkeys might rely on different directional cues guiding their attention, they seem to deploy a similar and possibly homologous cortical area to follow the gaze of a conspecific. Our results support the idea that the eyes developed a new social function in human evolution, most likely to support cooperative mutual social interactions building on a phylogenetically old STS module for the processing of head cues.     

Intravitreal injection of adeno-associated viral vectors results in the transduction of different types of retinal neurons in neonatal and adult rats: a comparison with lentiviral vectors

Replication-deficient viral vectors encoding the marker gene green fluorescent protein (GFP) were injected into the vitreous of newborn, juvenile (P14), and adult rats. We tested two different types of modified virus: adeno-associated viral-2-GFP (AAV-GFP) and lentiviral-GFP vectors (LV-GFP). The extent of retinal cell transduction in different-aged animals was compared 7, 21, and 70 days after eye injections. At all postinjection times, LV-GFP transduction was mostly limited to pigment epithelium and cells in sclera and choroid. In contrast, transduction of large numbers of neural retinal cells was seen 21 and 70 days after AAV-GFP injections. AAV-GFP predominantly transduced neurons, although GFP-positive Müller cells were seen. All neuronal classes were labeled, but the extent of transduction for a given class varied depending on injection age. After P0 injections about 50% of transduced cells were photoreceptors and 30-40% were amacrine or bipolar cells. After adult injections 60-70% of transduced cells were retinal ganglion cells. In adults many GFP-positive retinal axons were traced through the optic nerve/tract and terminal arbors were visualized in central targets.