Synaptic communication mediates the assembly of a self-organizing circuit that controls reproduction.

Migration of gonadotropin-releasing hormone (GnRH) neurons from their birthplace in the nasal placode to their hypothalamic destination is critical for vertebrate reproduction and species persistence. While their migration mode as individual GnRH neurons has been extensively studied, the role of GnRH-GnRH cell communication during migration remains largely unexplored. Here, we show in awake zebrafish larvae that migrating GnRH neurons pause at the nasal-forebrain junction and form clusters that act as interhemisphere neuronal ensembles. Within the ensembles, GnRH neurons create an isolated, spontaneously active circuit that is internally wired through monosynaptic glutamatergic synapses into which newborn GnRH neurons integrate before entering the brain. This initial phase of integration drives a phenotypic switch, which is essential for GnRH neurons to properly migrate toward their hypothalamic destination. Together, these experiments reveal a critical step for reproduction, which depends on synaptic communication between migrating GnRH neurons.

[«Salt and pepper¼ sign in the onset of a non-vascular pontine pathology]. / Signo de «sal y pimienta¼ como presentacion de una lesion pontina no vascular.

TITLE: Signo de «sal y pimienta¼ como presentacion de una lesion pontina no vascular.

Plasticity of the prolactin (PRL) axis: mechanisms underlying regulation of output in female mice.

The output of prolactin (PRL) is highly dynamic with dramatic changes in its secretion from the anterior pituitary gland depending on prevailing physiological status. In adult female mice, there are three distinct phases of output and each of these is related to the functions of PRL at specific stages of reproduction. Recent studies of the changes in the regulation of PRL during its period of maximum output, lactation, have shown alterations at both the level of the anterior pituitary and hypothalamus. The PRL-secreting cells of the anterior pituitary are organised into a homotypic network in virgin animals, facilitating coordinated bouts of activity between interconnected PRL cells. During lactation, coordinated activity increases due to the changes in structural connectivity, and this drives large elevations in PRL secretion. Surprisingly, these changes in connectivity are maintained after weaning, despite reversion of PRL output to that of virgin animals, and result in an augmented output of hormone during a second lactation. At the level of the hypothalamus, tuberoinfundibular dopamine (TIDA) neurons, the major inhibitors of PRL secretion, have unexpectedly been shown to remain responsive to PRL during lactation. However, there is an uncoupling between TIDA neuron firing and dopamine secretion, with a potential switch to enkephalin release. Such a process may reinforce hormone secretion through dual disinhibition and stimulation of PRL cell activity. Thus, integration of signalling along the hypothalamo-pituitary axis is responsible for increased secretory output of PRL cells during lactation, as well as allowing the system to anticipate future demands.

The role of p53 and anaplastic lymphoma kinase genes in the progression of cutaneous CD30(+) lymphoproliferative diseases.

BACKGROUND AND OBJECTIVES: Molecular events that precede transformations from lymphomatoid palulosis (LyP) to mycosis fungoides (MF) or to cutaneous anaplastic large cell lymphoma (ALCL) in the CD 30(+) cutaneous lymphoproliferative diseases (LPDs) are not known. Altered p(53) gene may be responsible since overexpression of the p(53) gene product has been reported in higher, but not in lower grades of cutaneous lymphomas. Expression of the anaplastic lymphoma kinase (ALK) gene product has also been described as an important prognostic indicator in ALCL. ALK positive systemic nodal ALCL are associated with a good prognosis. However, primary cutaneous ALCL that are ALK negative have a better overall survival. The current study was done to see if mutated p(53) gene or ALK reactivity were poor prognostic indicators in those patients with CD 30(+) cutaneous LPD who showed progression of the disease. METHODS: Mutations of the p(53) gene and expression of the ALK gene product were analysed in 36 patients (23 of LyP and 13 of CD30(+) cutaneous ALCL). Follow up data were available up till 5 yr in all patients. RESULTS: Clinical progression or histological transformation in sequential biopsy specimens was found in 9 of 36 patients. Transformation occurred in 5 patients (4 from LyP to ALCL and 1 from MF to ALCL) and clinical progression in 4 patients with ALCL. Mutations of the p(53) gene were found in two biopsy specimens of LyP. ALK gene products were not detected in any of the biopsy specimens of LyP and primary cutaneous ALCL. INTERPRETATION AND CONCLUSION: Although 9 of 36 patients with cutaneous CD30(+) LPDs had progression of their disease, neither mutations of the p(53) gene nor ALK immunoreactivity were found in any of these biopsies. The two cases of LyP that had mutated p(53) gene in their biopsy specimens showed no progression of their disease in the 5 yr follow up period. It appears that these molecular events may not play any significant role in the pathogenesis, progression or transformation of cutaneous CD30(+) LPD.

The value of scatter removal by a grid in full field digital mammography.

Our objective in this study was to investigate the usefulness of an anti-scatter grid in digital mammography using a contrast detail phantom. The mammography system we investigated was a GE Senographe 2000D. We carried out phantom measurements under various conditions with and without using the anti-scatter grid. A new version of the CDMAM phantom (version 3.4) was used. This phantom consists of a matrix of square cells with disks of varying size and contrast. For given exposure conditions detectability of these disks can be determined and used for construction of contrast detail curves. Previously, a computer program was developed at our institute that performs a fully automatic analysis of the phantom recordings using the ideal observer model. Breast thickness was simulated by a homogeneous layer of PMMA in the range of 1 to 7 cm. Series of images were recorded for different KeV and target-filter combinations depending on the simulated thickness. The dose was kept constant for each thickness with and without using a grid. It appeared that image quality improved for simulated breast thickness below 5 cm when the grid was removed. In the range from 5 to 7 cm contrast detail curves obtained with or without a grid were similar. Results suggest that for compressed breast thickness in the range of 1 to 7 cm a grid might not be needed in the digital mammography system we investigated. Below 5 cm, omitting the grid may allow lower dose to the patient without losing image quality.

Gap junctions mediate electrical signaling and ensuing cytosolic Ca2+ increases between chromaffin cells in adrenal slices: A role in catecholamine release.

In adrenal chromaffin cells, a rise in cytosolic calcium concentration ([Ca(2+)]i) is a key event in the triggering of catecholamine exocytosis after splanchnic nerve activation. Action potential- or nicotine-induced [Ca(2+)]i transients are well described in individual chromaffin cells, but whether they remain spatially confined to the stimulated cell or propagate to adjacent cells is not yet known. To address this issue, the spatiotemporal organization of electrical and associated Ca(2+) events between chromaffin cells was investigated using the patch-clamp technique and real-time confocal imaging in rat acute adrenal slices. Spontaneous or electrically evoked action potential-driven [Ca(2+)]i transients were simultaneously detected in neighboring cells. This was likely attributable to gap junction-mediated electrotonic communication, as shown by (1) the bidirectional reflection of voltage changes monitored between cell pairs, (2) Lucifer yellow (LY) diffusion between cells exhibiting spontaneous synchronized [Ca(2+)]i transients, and (3) the reduction of LY diffusion using the uncoupling agent carbenoxolone. Furthermore, transcripts encoding two connexins (Cx36 and Cx43) were found in single chromaffin cells. This gap junctional coupling was activated after a synaptic-like application of nicotine that mediated synchronous multicellular [Ca(2+)]i increases. In addition, nicotinic stimulation of a single cell triggered catecholamine release in coupled cells, as shown by amperometric detection of secretory events. Functional coupling between chromaffin cells in situ may represent an efficient complement to synaptic transmission to amplify catecholamine release after synaptic stimulation of a single excited chromaffin cell.

A New Class of Ruthenium Carbene Complexes: Synthesis and Structures of Highly Efficient Catalysts for Olefin Metathesis.

Cationic RuII carbene complexes with tBu2 PCH2 PtBu2 (dtbpm) as a chelating ligand, which are accessible by chloride abstraction from neutral precursors [(κ2 -dtbpm)Cl2 Ru=CHR] with trimethylsilyl triflate, are established as highly efficient ring opening metathesis polymerization catalysts (see scheme). Solv=solvent.

A critical review of the genotoxic potential of electric and magnetic fields.

55 published articles were identified which reported results of tests of ELF (extremely low frequency) or static electric or magnetic fields for genotoxic effects. The biological assays used spanned a wide range, including microbial systems, plants, Drosophila, mammalian and human cells in vitro and in vivo. Experimental results were grouped into four exposure categories: ELF Electric; ELF Magnetic; Static Electric; and Static Magnetic. The internal electric fields present in media (for in vitro experiments) and in the torso and extremities (for in vivo experiments) were estimated, providing an index of comparison. All experiments were critically analyzed with respect to basic data quality criteria. Experiments within each exposure category were then compared to determine if results reinforced or contradicted one another. The preponderance of evidence suggests that neither ELF nor static electric or magnetic fields have a clearly demonstrated potential to cause genotoxic effects. However, there may be genotoxic activity from exposure under conditions where phenomena auxiliary to an electric field, such as spark discharges, electrical shocks, or corona can occur. In addition, two unconfirmed reports suggest the genotoxic potential of certain chemical mutagens or ionizing radiation may be affected by co-exposure to electric or magnetic fields. Certain exposure categories are not represented or are under-represented by tests in some genotoxicity test systems that are usually included in minimal test batteries as specified by EPA for chemicals. It is suggested that consideration be given to whether additional genotoxicity testing is warranted to fill these gaps.

Oculoauriculovertebral anomaly: segregation analysis.

Seventy-four families of probands with oculoauriculovertebral anomaly were evaluated, including 116 parents and 195 offspring. Relatives were examined to identify ear malformations, mandibular anomalies, and other craniofacial abnormalities. For segregation analysis using POINTER, selection of the sample was consistent with single ascertainment. Different population liabilities were used for probands and relatives, because affection was narrowly defined for probands and broadly defined for relatives. The hypothesis of no genetic transmission was rejected. The evidence favored autosomal dominant inheritance; recessive and polygenic models were not distinguishable.

The role of preimplantation sonographic exposure in postimplantation development and pregnancy outcome.

To determine what, if any, effects exposure to ultrasonic beams has on preimplantation embryos we isolated mouse blastocysts and assessed resorption rate, pregnancy rate, decidual swelling volume, and live birth rate after in vitro exposure with subsequent transfer to surrogate mothers. The blastocyst stage embryos were isolated by flushing the uteri of pregnant animals with a phosphate buffered medium. Blastocysts at a discrete stage of development were pooled and transferred to a PB1-methylcellulose medium. This medium is specifically designed to maintain the embryos in a high viscosity solution during the sonographic exposure to prevent microcavitation. After the exposure, the embryos were washed free of methylcellulose and transferred to the uteri of pseudopregnant surrogate mothers. A total of 660 blastocyst stage embryos were distributed among seven treatment groups. After exposure, the embryos were transferred to 54 surrogate mothers. A total of 199 embryos were implanted successfully for postimplantation evaluation. An additional 427 blastocysts were distributed among four treatment groups and transferred to 46 surrogate mothers to assess the effect of sonographic exposure on birth rate. The results indicate possible deleterious effects (decreased implantation rate, increased resorption rate, decreased decidual swelling volume, and increased stillbirth rate) of short ultrasonic exposures (1 min and 5 min) on mouse blastocyst function.

Sister chromatid exchange analysis of human cells exposed to diagnostic levels of ultrasound.

Lymphocyte and lymphoblastoid cells were exposed in vitro to diagnostic levels of ultrasonic beams delivered by a Hewlett-Packard CE 30001 and a GE system with a 5 MHz linear transducer for 20 sec, 1 min, 5 min, and 20 min. Temperature and cavitation effects were controlled and there were matched sham exposures. The synergistic effects of theophylline with ultrasonography also were investigated. Small increases in sister chromatid exchange levels were observed after ultrasonic exposure, but increases were so small as to be unlikely to have clinical relevance. Theophylline was found to have no effect and ultrasonography had no effect on cell viability.

Method of cavitation-suppressed exposure of cells and explant mouse embryos to clinical real-time and pulsed Doppler ultrasound.

An apparatus and procedure for well-controlled exposure of cells or explant mouse embryos to clinical real-time ultrasound are described. Cells or embryos to be exposed are suspended in media made sufficiently viscous through inclusion of methylcellulose that cavitation is suppressed but thermal effects remain negligible. During exposure, the scanning beam is precisely centered in a 2 mm x 20 mm slot in a 20 cm diameter agar disc containing the suspension. The high viscosity causes the cells to remain distributed uniformly throughout the exposure; this fact, along with precision beam alignment, ensures that exposure is well defined. Exposure data are acquired with a 0.6 mm diameter hydrophone.

Diagnostic ultrasound is unable to enhance the rate of neoplastic transformation in cultured mammalian cells.

The ability of diagnostic pulsed ultrasound to induce heritable genetic damage of the type that could result in neoplasia was assayed using BHK21/cl 13 hamster cells or normal human fibroblasts as targets. Using an exposure apparatus carefully designed to minimize beam attenuation and reflection, cavitation, and heating, cells were exposed from 20 seconds to 40 minutes either to clinical machines operating at maximum power, or to a highly focused nonclinical transducer at 2900 W/cm2, or to 200 shocks from a lithotripter. No evidence of an increase in the frequency of neoplastically transformed BHK cells or in the frequency of mutant human cells was seen over those found in matched sham-exposed controls.

Maternal serum alpha-fetoprotein levels in pregnancies complicated by diabetes: implications for screening programs.

Maternal serum alpha-fetoprotein may be reduced in diabetic pregnancies, but the association with elevated glycosylated hemoglobin has been controversial. We tested the hypothesis that reductions in maternal serum alpha-fetoprotein may reflect the same phenomena that can also impair normal rates of embryo growth in the presence of poorly compensated maternal diabetes. If so, associations would be expected among maternal serum alpha-fetoprotein, embryo rates of growth, and levels of glycosylated hemoglobin reflective of regulation of maternal diabetes during the period of organogenesis. We found maternal serum alpha-fetoprotein levels in 93 pregnant patients with diabetes to be negatively associated with the earliest (4 to 12 weeks) glycosylated hemoglobin determinations. At glycosylated hemoglobin values greater than 9.6% (which approximates the upper quartile), all maternal serum alpha-fetoprotein values fell below the median for patients without diabetes (below 0.8 multiple of the median after weight adjustment). Moreover, there was a trend for pregnancies with lower maternal serum alpha-fetoprotein levels and higher glycosylated hemoglobin values to also demonstrate early fetal growth delay as measured by ultrasonography.

Cytogenetic results of chorionic villus sampling: high success rate and diagnostic accuracy in the United States collaborative study.

Cytogenetic results of first-trimester chorionic villus sampling are reported from seven U.S. medical centers. For 6033 patients who had a successful chorionic villus sampling procedure, the rate for obtaining a cytogenetic diagnosis was 99.6% with the direct method, long-term culture, or both. There were no incorrect sex predictions and no diagnostic errors involving trisomies 21, 18, or 13, sex chromosome aneuploidies, or structural abnormalities. There were no cases of normal cytogenetic diagnosis followed by birth of a cytogenetically abnormal infant. Three cases of unusual aneuploidies (tetraploidy, trisomy 16, and trisomy 22) detected by the direct method only were not confirmed by cytogenetic follow-up. Mosaic cytogenetic abnormalities were observed in 0.83% of all cases in which chorionic villus sampling was done but were confirmed by amniocentesis or in fetal tissues in only 7 of 30 cases (23.3%). Maternal cell contamination occurred in 1.9% of long-term cultures, although this did not present any cytogenetic diagnostic difficulties. Overall, a very high degree of laboratory success and diagnostic accuracy was observed with either cytogenetic method, although fewer predictive errors were observed with the long-term culture method and none were observed when both methods were used.

Stylized chromosome images.

Stylized chromosome images 1) serve as a format to test effects of preprocessing algorithms used in automated karyotyping; 2) enhance the ability of humans to perform quantitative analysis of chromosomal aberrations; 3) provide an alternative format for karyotype hard copies produced by automated systems. Stylized chromosomes are two-dimensional computer-generated images based on information extracted from one-dimensional width and density profiles. These profiles correspond to what cytogeneticists observe through the microscope as the shape and banding patterns of stained chromosomes. Stylized presentation sharpens chromosome band boundaries and perimeters, reduces "noise," and enhances gray level variations, which are difficult to distinguish by humans on photographic or computer generated karyotypes. Karyotyping accuracy using stylized images was used to detect difficult areas for automated chromosome identification. Landmark bands sufficient to classify chromosomes were identified; shapes of chromosomes reflected in width profiles were said to aid classification. A two-step automated karyotyping strategy proposed is: 1) classify chromosomes by landmarks, minimum information needed for identification; 2) subsequently employ the full banding pattern with maximum resolution to detect aberrations. Stylized images of abnormal chromosomes have potential for testing hypothesis regarding breakpoints and quantitative analysis, but improvements are needed in homologue normalization and definition of termini of chromosomes.

Microtia and associated anomalies: statistical analysis.

Terms such as oculoauriculovertebral dysplasia, Goldenhar syndrome, and hemifacial microsomia have been used to describe microtia with specific combinations of other craniofacial anomalies. Microtia is also observed with anomalies of postcranial structures. Statistical studies were performed on 297 patients with microtia and other anomalies to identify subgroups of patients representing previously described or new associations. Analysis identified 15 subgroups of patients with specific patterns of anomalies. Log-linear analyses of cranial and postcranial variables demonstrated a positive association between mandibular hypoplasia and cervical spine fusion, which was, in turn, positively associated with other spine anomalies (P less than .02) and other skeletal anomalies (P less than .001). Although unilateral microtia was commonly observed with mandibular hypoplasia, mandibular hypoplasia was negatively associated with bilateral microtia. Many of the associated anomalies were of structures not derived from the 1st and 2nd branchial arch neural crest. However, most associated anomalies were of structures derived from migratory cell populations or populations undergoing differentiation prior to migration between the 19th and 24th day post-fertilization (neural crest, ectodermal placode, mesoderm, surface ectoderm). These findings suggest that many different cell populations may be disturbed in the pathogenesis of microtia in association with other anomalies. The timing of the pathogenetic event may determine the specific pattern of associated anomalies.

Genetic analysis of HLA in the U.S. Schmiedenleut Hutterites.

The Hutterites are an Anabaptist population, highly inbred, with large family sizes and extensively documented pedigrees. As part of genetic-epidemiologic studies of the impact of HLA on fertility, HLA-A, -B, -C, -DR, and -DQ typing was performed on a total of 650 Schmiedenleut Hutterities in South Dakota. An extraordinary degree of homogeneity was found. HLA-A1, -A2, -A3, -A24, and -A26 accounted for 83%, HLA-B8, -B27, -B35, -B51, -Bw60, and -Bw62 for 75%, and HLA-DR1, -DR2, -DR3, and -DR4 for 66% of the antigens at the respective HLA-A, -B, and -DR loci. All Hutterites characterized for HLA were descendants of no more than 78 ancestors. However, family analysis identified only 45 unique HLA haplotypes thought to reflect the original gene pool. Eight haplotypes were particularly frequent, accounting for nearly 50% of all observed haplotypes; four of these were consistent with a European ancestry. Coefficients measuring linkage disequilibrium were computed from haplotypes identified by family analysis. Overall, HLA analysis portrayed the Schmiedenleut Hutterities as a homogeneous and unique population, with disequilibrium among particular alleles and a spectrum of common and uncommon European haplotypes.

Translocations are infrequent among couples having repeated spontaneous abortions but no other abnormal pregnancies.

During the years 1977 to 1986, cytogenetic studies were performed on 342 women and 297 men whose reproductive history included one or more first trimester spontaneous abortions. Thirty-nine women and 35 men experienced not only early fetal losses but also one or more stillborn infants, liveborn anomalous infants, or early neonatal deaths. Among the 303 women and 262 men evaluated solely because of repetitive abortions, only 1 woman and 1 man showed a translocation. Two translocations were detected among the 39 women and 35 men having not only repetitive abortions but also a stillborn infant, anomalous liveborn, or unexplained neonatal death. Only among the 25 women having abortions and other abnormal perinatal events was the frequency of translocations high (2/25 or 8%). Our data continue to indicate that balanced chromosomal translocations are relatively infrequent in individuals having repeated abortions but no other adverse perinatal outcome.