Early effects of iodine deficiency on radial glial cells of the hippocampus of the rat fetus. A model of neurological cretinism.

The most severe brain damage associated with thyroid dysfunction during development is observed in neurological cretins from areas with marked iodine deficiency. The damage is irreversible by birth and related to maternal hypothyroxinemia before mid gestation. However, direct evidence of this etiopathogenic mechanism is lacking. Rats were fed diets with a very low iodine content (LID), or LID supplemented with KI. Other rats were fed the breeding diet with a normal iodine content plus a goitrogen, methimazole (MMI). The concentrations of -thyroxine (T4) and 3,5,3'triiodo--thyronine (T3) were determined in the brain of 21-d-old fetuses. The proportion of radial glial cell fibers expressing nestin and glial fibrillary acidic protein was determined in the CA1 region of the hippocampus. T4 and T3 were decreased in the brain of the LID and MMI fetuses, as compared to their respective controls. The number of immature glial cell fibers, expressing nestin, was not affected, but the proportion of mature glial cell fibers, expressing glial fibrillary acidic protein, was significantly decreased by both LID and MMI treatment of the dams. These results show impaired maturation of cells involved in neuronal migration in the hippocampus, a region known to be affected in cretinism, at a stage of development equivalent to mid gestation in humans. The impairment is related to fetal cerebral thyroid hormone deficiency during a period of development when maternal thyroxinemia is believed to play an important role.

Pancreatic ductal adenocarcinoma: metastatic disease.

The treatment of choice of metastatic PADC is systemic chemotherapy. In the last decade, there have been significant advances in this area. New combination poli-chemotherapy schemes have shown a significant increase in overall survival and progression-free survival without impairing quality of life. In addition, the value of second-line chemotherapy treatment has consolidated and a new concept called "therapeutic sequencing" has also emerged. The aim of this article is to review the different therapeutic options in metastatic PDAC based on patient's characteristics.

Multidisciplinary management of head and neck cancer: First expert consensus using Delphi methodology from the Spanish Society for Head and Neck Cancer (part 1).

Head and neck cancer is one of the most frequent malignances worldwide. Despite the site-specific multimodality therapy, up to half of the patients will develop recurrence. Treatment selection based on a multidisciplinary tumor board represents the cornerstone of head and neck cancer, as it is essential for achieving the best results, not only in terms of outcome, but also in terms of organ-function preservation and quality of life. Evidence-based international and national clinical practice guidelines for head and neck cancer not always provide answers in terms of decision-making that specialists must deal with in their daily practice. This is the first Expert Consensus on the Multidisciplinary Approach for Head and Neck Squamous Cell Carcinoma (HNSCC) elaborated by the Spanish Society for Head and Neck Cancer and based on a Delphi methodology. It offers several specific recommendations based on the available evidence and the expertise of our specialists to facilitate decision-making of all health-care specialists involved.

Phase II trial of miniDOX (reduced dose docetaxel-oxaliplatin-capecitabine) in "suboptimal" patients with advanced gastric cancer (AGC). TTD 08-02.

PURPOSE: Chemotherapy has improved the overall survival (OS) in patients (pts) with advanced gastric cancer (AGC). Docetaxel (D), oxaliplatin (O) and capecitabine (C) have shown interesting activity in this setting. We defined "suboptimal" pts as those with PS ECOG = 2, weight loss 10-25% and/or age ≥70 years. This population is usually underrepresented in AGC clinical trials. METHODS: We explored in 43 previously untreated "suboptimal" AGC pts the effect of "miniDOX" regimen (D: 40 mg/m(2) iv, day 1; O: 80 mg/m(2) iv, day 1; C: 625 mg/m(2) po bid, day 1 to day 21, every 21 days; after six courses, only C was maintained). Primary end point was response rate (RR), and secondary end points were adverse events (AE), progression-free survival (PFS) and overall survival (OS). RESULTS: Patients characteristics: PS ECOG = 2: 12 pts; weight loss 10-25%: 23 pts; median age 73.3 years (range 40-87; 28 pts were ≥70 years); 32 males; locally advanced: 8 pts/metastatic: 35 pts; primary site: gastric 32 pts/EGJ 11. Worst AE per pt (grade 3-4): neutropenia: 5 pts (febrile neutropenia: 3); pulmonary embolism (PE): 4 pts (3 of them suffered sudden death); diarrhea: 9 pts; paronychia: 2 pts; ictus: 1 pt; renal failure: 1 pt (this pt suffered infection/bacteriemia without neutropenia and died); hand-foot syndrome: 4 pts and asthenia: 5 pts. RESPONSE: CR: 1 pt, PR: 23 pts (RR: 56%), SD: 12 pts, progression: 3 pts, no determined: 4 pts. Median and 1 year actuarial PFS and OS were 5.5 months/18% and 13.3 months/52%, respectively. CONCLUSIONS: Although miniDOX's toxicity (mainly PE)has been important, its activity has been promising in "suboptimal" pts with AGC, and this combination should be further investigated in this setting.

Different origins and developmental histories of transient neurons in the marginal zone of the fetal and neonatal rat cortex.

Two major classes of early-born neurons are distinguished during early corticogenesis in the rat. The first class is formed by the cortical pioneer neurons, which are born in the ventricular neuroepithelium all over the cortical primordium. They appear at embryonic day (E) 11.5 in the lateral aspect of the telencephalic vesicle and cover its whole surface on E12. These cells, which show intense immunoreactivity for calbindin and calretinin, are characterized by their large size and axonal projection. They remain in the marginal zone after the formation of the cortical plate; they project first into the ventricular zone, and then into the subplate and the internal capsule. Therefore, these cells are the origin of the earliest efferent pathway of the developing cortex. Pioneer neurons are only present in prenatal brains. The second class is formed by subpial granule neurons, which form the subpial granular layer (SGL), previously considered to be found exclusively in the human cortex. SGL neurons are smaller than pioneer neurons. They are generated in a transient compartment of the retrobulbar ventricle between E12 and E14, and we propose the hypothesis that they invade the marginal zone, through tangential subpial migration, at different moments of fetal life. SGL neurons contain calbindin, calretinin, and gamma-aminobutyric acid (GABA), but the GABA-immunoreactive group becomes inconspicuous before birth. The extracellular matrix-like glycoprotein reelin, a molecule crucial for cortical lamination, is prenatally expressed by SGL neurons; postnatally, it is present in both Cajal-Retzius cells and subpial pyriform cells, both derivatives of SGL cells. In the rat, Cajal-Retzius cells are horizontal neurons that remain only until the end of the first postnatal week. They are located in layer I at a critical distance of approximately 20 microm from the pial surface and express reelin and, only occasionally, calretinin. Subpial pyriform cells coexpress reelin and calretinin and remain in layer I longer than Cajal-Retzius cells. Both pioneer neurons and subpial granule neurons are specific to the cortex. They mark the limit between the rudimentary cerebral cortex and olfactory bulb in the rat during early corticogenesis.

Myelin basic protein immunoreactivity in the internal capsule of neonates from rats on a low iodine intake or on methylmercaptoimidazole (MMI).

Rats fed on low iodine diets (LIDs) result in a normal circulating level of triiodothyronine (T3), a low level of thyroxine (T4) and an elevated thyroid-stimulating hormone (TSH). These changes are similar to those observed in habitants who live in iodine-deficient areas and different from those observed when the hypothyroidism is produced by goitrogens. To study the effects of LID or goitrogens on the myelin basic protein (MBP) immunoreactivity (MBP-ir) during the myelination of the internal capsule, one group of experimental female rats was fed on an LID, and another group received a standard laboratory diet with methylmercaptoimidazole (MMI) added in the drinking water. Animals fed on a standard laboratory diet and animals fed on an LID supplemented with KI were used as controls. At P10, the MMI treatment has produced a more marked decrease in the surface density of MBP-ir processes with respect to controls than that produced in the LID animals. This decrease was correlated with the cerebral concentrations of triiodothyronine (T3) we found. During the postnatal development, a recovery in the levels of the surface density with respect to controls was observed in both experimental groups. The recovery occurred by P20 in the LID group and by P32 in the MMI rats.

PKCepsilon upregulates voltage-dependent calcium channels in cultured astrocytes.

Astrocytes express voltage-gated calcium channels (VGCCs) that are upregulated in the context of the reactive astrogliosis occurring in several CNS pathologies. Moreover, the ability of selective calcium channel blockers to inhibit reactive astrogliosis has been revealed in a variety of experimental models. However, the functions and regulation of VGCC in astrocytes are still poorly understood. Interestingly, protein kinase C epsilon (PKCepsilon), one of the known regulators of VGCC in several cell types, induces in astrocytes a stellated morphology similar to that associated to gliosis. Thereby, here we explored the possible regulation of VGCC by adenovirally expressed PKCepsilon in astrocytes. We found that PKCepsilon potently increases the mRNA levels of two different calcium channel alpha(1) subunits, Ca(V)1.2 (L-type channel) and Ca(V)2.1 (P/Q-type channel). The mRNA upregulation was followed by a robust increase in the corresponding peptides. Moreover, the new calcium channels formed as a consequence of PKCepsilon activation are functional, since overexpression of constitutively-active PKCepsilon increased significantly the calcium current density in astrocytes. PKCepsilon raised currents carried by both L- and P/Q-type channels. However, the effect on the P/Q-type channel was more prominent since an increase of the relative contribution of this channel to the whole cell calcium current was observed. Finally, we found that PKCepsilon-induced stellation was significantly reduced by the specific L-type channel blocker nifedipine, indicating that calcium influx through VGCC mediates the change in astrocyte morphology induced by PKCepsilon. Therefore, here we describe a novel regulatory pathway involving VGCC that participates in PKCepsilon-dependent astrocyte activation.

Functional NMDA and GABAA receptors in pioneer neurons of the cortical marginal zone.

Transient pioneer neurons in the neocortical marginal zone generate an early corticofugal axonal projection at E12-E16 (Meyer et al. 1998). We have analysed the functional activity of glutamate and GABA receptors in such cells by measuring changes in intracellular calcium concentrations ([Ca2+]i). The activation of GABAA receptors with muscimol, as well as bath application of glutamate, lead to increases in [Ca2+]i in pioneer neurons. The stimulatory action of glutamate is mostly produced through the NMDA-type of ionotropic receptors. Metabotropic glutamate receptor activation has no effect on [Ca2+]i. Consistent with such results, immunocytochemical studies showed a prominent expression of GABAA and NMDA receptors in pioneer neurons. The activation of such receptors may be implicated in the remodelling of pioneer neurons during development.

Cajal-Retzius cells in early postnatal mouse cortex selectively express functional metabotropic glutamate receptors.

Glutamate receptors have been linked to the regulation of several developmental events in the CNS. By using cortical slices of early postnatal mice, we show that in layer I cells, glutamate produces intracellular calcium ([Ca(2+)](i)) elevations mediated by ionotropic and metabotropic glutamate receptors (mGluRs). The contribution of mGluRs to these responses was demonstrated by application of tACPD, an agonist to groups I and II mGluRs, which evoked [Ca(2+)](i) increases that could be reversibly blocked by MCPG, an antagonist to groups I and II mGluRs. In the absence of extracellular Ca(2+), repetitive applications of tACPD or quisqualate, an agonist to group I mGluRs, elicited decreasing [Ca(2+)](i) responses that were restored by refilling a thapsigargin-sensitive Ca(2+) store. The use of specific group I mGluR agonists CHPG and DHPG indicated that the functional mGluR in layer I was of the mGluR1 subtype. Subtype specific antibodies confirmed the presence of mGlur1 alpha, but not mGluR5, in Cajal-Retzius (Reelin-immunoreactive) neurons.

Thyroxine treatment and the recovery of pyramidal cells of the cerebral cortex from changes induced by juvenile-onset hypothyroidism.

In contrast to the permanent alterations resulting from neonatal hypothyroidism, the effects of juvenile-onset hypothyroidism on the number and distribution of spines along the apical shaft of pyramidal neurons of the visual cortex appeared to be potentially reversible with adequate thyroxine (T4) therapy (Ruiz-Marcos et al., 1980, Brain Res. 185:91-102 and 1982, Brain Res. 239:559-574). Treatment with 0.20 or 1.50 micrograms T4/100 g body weight per day had, however, only partially reversed the changes induced by juvenile-onset hypothyroidism. We here study whether or not a higher dose of T4 would totally reverse these effects. A group of rats were thyroid-ectomized at 40 days of age, and injected once daily with placebo or T4 (1.75 micrograms/100 g BW per day) from 70 to 90 days of age, a group on 1.50 micrograms being included to compare with previous results. Spine number and distribution were measured, as well as the concentrations of T4 and triiodothyronine (T3) in plasma, liver and brain. The activities of two hepatic enzymes were measured as thyroid hormone-sensitive biological end points. The 1.75-micrograms dose restored spine number to 88% of normal values and was markedly more effective than the 1.50-micrograms dose, which increased it to 68%. The degree of restoration appeared related to the concentration of T3. It is concluded that the changes caused by juvenile-onset hypothyroidism in the number and distribution of dendritic spines along the apical shafts of pyramidal neurons are reversible, although complete restoration might require a higher dose of T4, a continuous mode of administration, or longer period of treatment.