Variability in Cochlear Implantation Outcomes in a Large German Cohort With a Genetic Etiology of Hearing Loss

OBJECTIVES

The variability in outcomes of cochlear implantation is largely unexplained, and clinical factors are not sufficient for predicting performance. Genetic factors have been suggested to impact outcomes, but the clinical and genetic heterogeneity of hereditary hearing loss makes it difficult to determine and interpret postoperative performance. It is hypothesized that genetic mutations that affect the neuronal components of the cochlea and auditory pathway, targeted by the cochlear implant (CI), may lead to poor performance. A large cohort of CI recipients was studied to verify this hypothesis.

DESIGN

This study included a large German cohort of CI recipients (n = 123 implanted ears; n = 76 probands) with a definitive genetic etiology of hearing loss according to the American College of Medical Genetics (ACMG)/Association for Molecular Pathology (AMP) guidelines and documented postoperative audiological outcomes. All patients underwent preoperative clinical and audiological examinations. Postoperative CI outcome measures were based on at least 1 year of postoperative audiological follow-up for patients with postlingual hearing loss onset (>6 years) and 5 years for children with congenital or pre/perilingual hearing loss onset (≤6 years). Genetic analysis was performed based on three different methods that included single-gene screening, custom-designed hearing loss gene panel sequencing, targeting known syndromic and nonsyndromic hearing loss genes, and whole-genome sequencing.

RESULTS

The genetic diagnosis of the 76 probands in the genetic cohort involved 35 genes and 61 different clinically relevant (pathogenic, likely pathogenic) variants. With regard to implanted ears (n = 123), the six most frequently affected genes affecting nearly one-half of implanted ears were GJB2 (21%; n = 26), TMPRSS3 (7%; n = 9), MYO15A (7%; n = 8), SLC26A4 (5%; n = 6), and LOXHD1 and USH2A (each 4%; n = 5). CI recipients with pathogenic variants that influence the sensory nonneural structures performed at or above the median level of speech performance of all ears at 70% [monosyllable word recognition score in quiet at 65 decibels sound pressure level (SPL)]. When gene expression categories were compared to demographic and clinical categories (total number of compared categories: n = 30), mutations in genes expressed in the spiral ganglion emerged as a significant factor more negatively affecting cochlear implantation outcomes than all clinical parameters. An ANOVA of a reduced set of genetic and clinical categories (n = 10) identified five detrimental factors leading to poorer performance with highly significant effects ( p < 0.001), accounting for a total of 11.8% of the observed variance. The single strongest category was neural gene expression accounting for 3.1% of the variance.

CONCLUSIONS

The analysis of the relationship between the molecular genetic diagnoses of a hereditary etiology of hearing loss and cochlear implantation outcomes in a large German cohort of CI recipients revealed significant variabilities. Poor performance was observed with genetic mutations that affected the neural components of the cochlea, supporting the "spiral ganglion hypothesis."

Drosophila functional screening of de novo variants in autism uncovers damaging variants and facilitates discovery of rare neurodevelopmental diseases

Individuals with autism spectrum disorder (ASD) exhibit an increased burden of de novo mutations (DNMs) in a broadening range of genes. While these studies have implicated hundreds of genes in ASD pathogenesis, which DNMs cause functional consequences in vivo remains unclear. We functionally test the effects of ASD missense DNMs using Drosophila through "humanization" rescue and overexpression-based strategies. We examine 79 ASD variants in 74 genes identified in the Simons Simplex Collection and find 38% of them to cause functional alterations. Moreover, we identify GLRA2 as the cause of a spectrum of neurodevelopmental phenotypes beyond ASD in 13 previously undiagnosed subjects. Functional characterization of variants in ASD candidate genes points to conserved neurobiological mechanisms and facilitates gene discovery for rare neurodevelopmental diseases.

A New Panel-Based Next-Generation Sequencing Method for ADME Genes Reveals Novel Associations of Common and Rare Variants With Expression in a Human Liver Cohort

We developed a panel-based NGS pipeline for comprehensive analysis of 340 genes involved in absorption, distribution, metabolism and excretion (ADME) of drugs, other xenobiotics, and endogenous substances. The 340 genes comprised phase I and II enzymes, drug transporters and regulator/modifier genes within their entire coding regions, adjacent intron regions and 5′ and 3′UTR regions, resulting in a total panel size of 1,382 kbp. We applied the ADME NGS panel to sequence genomic DNA from 150 Caucasian liver donors with available comprehensive gene expression data. This revealed an average read-depth of 343 (range 27–811), while 99% of the 340 genes were covered on average at least 100-fold. Direct comparison of variant annotation with 363 available genotypes determined independently by other methods revealed an overall accuracy of >99%. Of 15,727 SNV and small INDEL variants, 12,022 had a minor allele frequency (MAF) below 2%, including 8,937 singletons. In total we found 7,273 novel variants. Functional predictions were computed for coding variants (n = 4,017) by three algorithms (Polyphen 2, Provean, and SIFT), resulting in 1,466 variants (36.5%) concordantly predicted to be damaging, while 1,019 variants (25.4%) were predicted to be tolerable. In agreement with other studies we found that less common variants were enriched for deleterious variants. Cis-eQTL analysis of variants with (MAF ≥ 2%) revealed significant associations for 90 variants in 31 genes after Bonferroni correction, most of which were located in non-coding regions. For less common variants (MAF < 2%), we applied the SKAT-O test and identified significant associations to gene expression for ADH1C and GSTO1. Moreover, our data allow comparison of functional predictions with additional phenotypic data to prioritize variants for further analysis.

Impact of p38 MAP Kinase Inhibitors on LPS-Induced Release of TNF-α in Whole Blood and Primary Cells from Different Species

BACKGROUND/AIMS

Inhibition of p38 mitogen-activated protein kinase (p38 MAPK) is promising for the treatment of inflammatory disorders, however, the efficacy of p38 MAPK inhibitors in clinical trials is limited so far. Since functional sensitivity of p38 MAPK is commonly predicted by preclinical species, we systematically investigated interspecies differences including human tissue.

METHODS

Ex vivo test models were established using whole blood and primary cells from different species such as mice, rats, pigs and humans to compare LPS-induced TNF-α inhibition of four different p38 MAPK reference inhibitors SB 203580, BIRB-796, Pamapimod, and a Losmapimod analogue as well as a proprietary imidazole-based p38 MAPK Inhibitor.

RESULTS

All analysed p38 MAPK inhibitors resulted in significant inhibition of LPS-induced TNF-α release but with high interspecies differences for dose sensitivity. IC50 values from human whole blood and PBMC showed significant higher sensitivity towards p38 MAPK inhibition compared with data from pig and rat.

CONCLUSION

Inhibition of TNF-α release by p38 MAPK inhibitors can be reliably identified in well-established laboratory species such as rat or mouse. However, our data indicate that animal models appear to be limited for valid prediction of the inhibitory potential for TNF-α release in humans. Thus, human tissues should be considered early in the drug development process of p38 MAPK inhibitors.

What does the nature of the MECP2 mutation tell us about parental origin and recurrence risk in Rett syndrome?

The MECP2 mutations occurring in the severe neurological disorder Rett syndrome are predominantly de novo, with rare familial cases. The aims of this study were to provide a precise estimate of the parental origin of MECP2 mutations using a large Chinese sample and to assess whether parental origin varied by mutation type. The parental origin was paternal in 84/88 [95.5%, (95% confidence interval 88.77-98.75)] of sporadic Chinese cases. However, in a pooled sample including data from the literature the spectrum of mutations occurring on maternally and paternally derived chromosomes differed significantly. The excess we found of 'single base pair gains or losses' on maternally derived MECP2 gene alleles suggests that this mutational category is associated with an elevated risk of gonadal mosaicism, which has implications for genetic counseling.

Spatio-temporal expression analysis of the calcium-binding protein calumenin in the rodent brain

Calumenin is a Ca²⁺-binding protein that belongs to the CREC superfamily. It contains six EF-hand domains that exhibit a low affinity for Ca²⁺ as well as an endoplasmic reticulum retention signal. Calumenin exhibits a broad and relatively high expression in various brain regions during development as demonstrated by in situ hybridization. Signal intensity of calumenin is highest during the early development and then declines over time to reach a relatively low expression in adult animals. Immunohistochemistry indicates that at the P0 stage, calumenin expression is most abundant in migrating neurons in the zones around the lateral ventricle. In the brain of adult animals, it is expressed in various glial and neuronal cell types, including immature neurons in subgranular zone of hippocampal dentate gyrus. At the subcellular level, calumenin is identified in punctuate and diffuse distribution mostly in somatic regions where it co-localizes with endoplasmic reticulum (ER) and partially Golgi apparatus. Upon subcellular fractionation, calumenin is enriched in fractions containing membranes and is only weakly present in soluble fractions. This study points to a possible important role of calumenin in migration and differentiation of neurons, and/or in Ca²⁺ signaling between glial cells and neurons.

Antihypertensive therapy upregulates renin and (pro)renin receptor in the clipped kidney of Goldblatt hypertensive rats

Recently, a (pro)renin receptor has been identified which mediates profibrotic effects independent of angiotensin II. Because antihypertensive therapy induces renal injury in the clipped kidney of two kidney-1-clip hypertensive rats, we examined the regulation of renin and the (pro)renin receptor in this model. Hypertensive Goldblatt rats were treated with increasing doses of the vasopeptidase inhibitor AVE 7688 after which the plasma renin and prorenin as well as the renal renin and (pro)renin receptor expression were measured. The vasopeptidase inhibitor dose-dependently lowered blood pressure, which was associated with a massive increase in plasma prorenin and renin as well as increased renal renin expression. The (pro)renin receptor was upregulated in the clipped kidney of the Goldblatt rat indicating a parallel upregulation of renin and its receptor in vivo. Immunohistochemistry showed a redistribution of renin upstream from the glomerulus in preglomerular vessels and renin staining in tubular cells. Expression of the (pro)renin receptor was increased in the vessels and tubules. This upregulation was associated with thickening of renin-positive vessels and tubulointerstitial damage. We propose that renin and the (pro)renin receptor may play a profibrotic role in the clipped kidney of Goldblatt rats treated for hypertension.

A pitfall of glomerular sieving: profibrotic and matrix proteins derive from the Bowman's capsule and not the glomerular tuft in rats with renovascular hypertension

BACKGROUND

The glomeruli in the non-clipped kidney of rats with 2-kidney, 1-clip hypertension are a classical model for studying the mechanisms of glomerular injury.

METHODS

In the present study, we compared the glomerular expression of PAI-1 and collagen I alpha1 mRNA from glomeruli isolated by the classic technique of sieving with the recently developed technique of tissue laser microdissection. For quantification of mRNA from both methods, real-time PCR was used.

RESULTS

Real-time PCR revealed a 9.0 +/- 1.3- and a 7.1 +/- 0.2-fold induction of PAI-1 and collagen I alpha 1, respectively, in the glomeruli from hypertensive rats isolated by sieving. However, in situ hybridization and microdissection revealed that expression of both mRNAs was mainly from the Bowman's capsule and not from the glomerular tuft (10.7 +/- 1.3- and 7.2 +/- 0.6-fold higher induction in whole glomeruli compared with tuft alone).

CONCLUSION

This emphasizes that studies focusing on processes in the mesangium, endothelial cells or podocytes should not rely on glomeruli obtained by sieving. Rather, a technique like the laser microdissection or in situ hybridization should be applied which allows the clear separation of different glomerular and periglomerular compartments.

[Back pain and acne conglobata: SAPHO syndrome]

We report on a young woman suffering from SAPHO syndrome with back pain and arthritis of the sternoclavicular joints. This inflammatory disorder of the osteoarticular system (synovitis, osteitis, and hyperostosis) is associated with severe acne or palmoplantar pustulosis. The patient was treated with pamidronate, NSAID and physiotherapy which improved the musculoskeletal symptoms completely. The acne was treated with isotretinoin.

Antihypertensive therapy induces compartment-specific chemokine expression and a Th1 immune response in the clipped kidney of Goldblatt hypertensive rats

The present study examined the pathogenesis of interstitial inflammation and fibrosis in antihypertensively treated rats with two-kidney, one-clip hypertension. Hypertensive rats were randomized into four groups: no treatment and moderate, intermediate, and intensified lowering of blood pressure with increasing doses of a vasopeptidase inhibitor for 6 wk. The vasopeptidase inhibitor dose dependently lowered blood pressure. The tubulointerstitial damage was accompanied by a diffuse infiltration of mononuclear cells and circumscript mononuclear inflammatory cell cluster formation consisting mainly of T cells and to a lesser degree of macrophages and B cells. Real-time PCR analyses showed a dose-dependent induction of MCP-1 and the Th1-type chemokines IP10 and Mig as well as their receptor CXCR3 and the Th1 cytokine IFN-γ. In situ hybridization and laser microdissection revealed a strong expression of these Th1-associated transcripts in the clusters and, in the case of MCP-1, also diffusely in the interstitium. The inflammation was accompanied by the appearance of myofibroblasts and synthesis of the fibrogenic factor plasminogen activator inhibitor-1 as well as the collagenase matrix metalloproteinase-2, leading to collagen I upregulation and interstitial scarring. No inflammation or fibrosis was found in normotensive rats treated with the vasopeptidase inhibitor. The renal injury in the clipped kidney is accompanied by compartment-specific chemokine expression and cell cluster formation of Th1 specificity associated with upregulation of fibrogenic proteins and matrix metalloproteinases. These findings suggest that the Th1 chemokines IP10 and Mig as well as their receptor CXCR3 are potential targets for therapeutic interventions in ischemic nephropathy.

Start-up delays of infusion syringe pumps

BACKGROUND

We performed a bench experiment to investigate the extent of start-up delays in fluid delivery for four different syringe pumps after initially placing the infusion syringe in the syringe pump.

METHODS

Pump performance was determined at an infusion rate of 1 ml.h-1 with and without a fluid bolus delivered by the infusion pump prior to connecting the infusion line to the simulated patient.

RESULTS

The time (mean +/- SD) from starting the pump up to first fluid delivery (t1) differed considerably between pumps (from 6.75 +/- 4.4 to 57.2 +/- 28.6 min) as did the time to steady state fluid delivery (t2) (from 19.6 +/- 9.3 to 76.3 +/- 29.0 min). Applying an initial bolus of 2 ml before connecting the line to the simulated patient practically eliminated the delay in fluid delivery (t1 ranging from 0.3 +/- 0.1 to 1.1 +/- 0.8 min). This manoeuvre also reduced the time to steady flow delivery (t2 from 6.0 +/- 3.1 to 11.1 +/- 4.3 min, P<0.001) and minimized the differences between syringe pumps.

CONCLUSIONS

Syringe pump design affects start-up delay times because of free play of the syringe. These delays can be eliminated by a start-up bolus of 2 ml prior to connecting the infusion line to the patient.

Corticosteroids impair intestinal epithelial wound repair mechanisms in vitro

BACKGROUND

Despite enormous progress in the medical treatment of inflammatory bowel diseases (IBD), corticosteroids still represent the most effective drugs in the management of acute IBD. Unfortunately, surgical intervention under concomitant therapy with corticosteroids is often complicated by impaired intestinal wound healing. Our aim was to assess the effects of the corticosteroids prednisolone and budesonide on different aspects of intestinal epithelial wound healing in vitro to identify potential causes for impaired intestinal wound healing under corticosteroid therapy.

METHODS

The effects of both corticosteroids on intestinal epithelial cell function were studied in non-transformed small intestinal epithelial intestinal epithelial cell line IEC-6 cells and human colon cancer-derived HT-29 cells. Effects on epithelial migration were assessed using an in vitro wounding model. Effects on epithelial cell proliferation were assessed using colorimetric 3(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) assays. Transforming Growth Factor beta (TGFbeta) mRNA and protein expression were determined by semi-quantitative RT-PCR and ELISA.

RESULTS

Prednisolone and budesonide caused a significant dose-dependent inhibition of intestinal epithelial cell migration and proliferation in IEC-6 and HT-29 cells. Both corticosteroids induced apoptosis of intestinal epithelial cells in a dose-dependent fashion. Neither corticosteroid modulated the expression of TGFbeta mRNA and the synthesis of TGFbeta peptide. However, both corticosteroids stimulated the bioactivation of latent TGFbeta peptide.

CONCLUSIONS

Prednisolone and budesonide inhibit intestinal epithelial cell restitution and proliferation in vitro. Both processes play a key role in the rapid resealing of the mucosal barrier following intestinal injury. Thus, impaired intestinal epithelial wound healing under corticosteroid therapy in vivo may be caused by inhibition of intestinal epithelial cell restitution and proliferation.

Evaluation of the FASTSTART mode for reducing start-up delay in syringe pump infusion systems

OBJECTIVE

The aim of the study was to evaluate the IVAC P7000 FASTSTART mode with regard to start-up performance in a 50-ml infusion syringe at a flow rate of 1 ml.h-1.

METHODS

The time from depression of the start button to first fluid flow (T1) and to establishment of a pre-set flow rate (T2) were gravimetrically recorded with and without FASTSTART and with and without priming of the infusion system with a 1-ml fluid bolus prior to connection of the infusion line to the patient.

RESULTS

FASTSTART significantly reduced start-up times in the unprimed syringe pump infusion system from (mean [SD]) 9.4 (6.0) to 2.5 (3.5) min for T1 and from 21.8 (9.8) to 9.4 (6.2) min for T2 (all p < 0.001). The greatest improvement in shortening of T1 and T2 was obtained when the system was primed prior to starting (p < 0.0001). After priming the infusion system, FASTSTART shortened T2 by some 50% from 1.4 (1.4) to 0.7 (0.6) min.

CONCLUSION

Our data indicate that the FASTSTART procedure is effective and that substantial improvements can be obtained by priming the system prior to starting.

Evaluation of the FASTSTART mode for reducing start-up delay in syringe pump infusion systems

OBJECTIVE

The aim of the study was to evaluate the IVAC P7000 FASTSTART mode with regard to start-up performance in a 50-ml infusion syringe at a flow rate of 1 ml.h-1.

METHODS

The time from depression of the start button to first fluid flow (T1) and to establishment of a pre-set flow rate (T2) were gravimetrically recorded with and without FASTSTART and with and without priming of the infusion system with a 1-ml fluid bolus prior to connection of the infusion line to the patient.

RESULTS

FASTSTART significantly reduced start-up times in the unprimed syringe pump infusion system from (mean [SD]) 9.4 (6.0) to 2.5 (3.5) min for T1 and from 21.8 (9.8) to 9.4 (6.2) min for T2 (all p < 0.001). The greatest improvement in shortening of T1 and T2 was obtained when the system was primed prior to starting (p < 0.0001). After priming the infusion system, FASTSTART shortened T2 by some 50% from 1.4 (1.4) to 0.7 (0.6) min.

CONCLUSION

Our data indicate that the FASTSTART procedure is effective and that substantial improvements can be obtained by priming the system prior to starting.

A constitutively open potassium channel formed by KCNQ1 and KCNE3

Mutations in all four known KCNQ potassium channel alpha-subunit genes lead to human diseases. KCNQ1 (KvLQT1) interacts with the beta-subunit KCNE1 (IsK, minK) to form the slow, depolarization-activated potassium current I(Ks) that is affected in some forms of cardiac arrhythmia. Here we show that the novel beta-subunit KCNE3 markedly changes KCNQ1 properties to yield currents that are nearly instantaneous and depend linearly on voltage. It also suppresses the currents of KCNQ4 and HERG potassium channels. In the intestine, KCNQ1 and KCNE3 messenger RNAs colocalized in crypt cells. This localization and the pharmacology, voltage-dependence and stimulation by cyclic AMP of KCNQ1/KCNE3 currents indicate that these proteins may assemble to form the potassium channel that is important for cyclic AMP-stimulated intestinal chloride secretion and that is involved in secretory diarrhoea and cystic fibrosis.

Organization and expression of bovine TSPY

We have isolated genomic sequences as well as transcripts from the bovine homolog of the human testis-specific protein, Y-encoded, TSPY which-in both species-is located on the Y Chromosome (Chr), organized as a gene family with a variable number of members, and expressed exclusively in the testis. 1266 bp of bovine TSPY specific sequence have been isolated from a testis cDNA library, by RT-PCR analyses and by Rapid Amplification of cDNA Ends (RACE). A bovine TSPY gene 4 is organized in seven exons, and transcripts are polyadenylated at various 3' ends. Consensus polyadenylation signals AAUUAAA are missing. Microheterogeneous sequence variation is found between TSPY family members. In addition, homologies to other Y-located repeated sequence families, BRY, have been discovered; these sequences are presumably derived from ancient members of the TSPY cluster, now forming a separate, probably nonfunctional subfamily. Bovine TSPY is subject to differential splicing. In the adult, it is expressed in early germ-cell stages, and expression could also be detected in fetal testis. Comparison with the human homolog shows the highest degree of similarity in the coding regions of exons 2, 3, and 4, which are also precisely conserved regarding their length.

Dendritic localization of rat vasopressin mRNA: ultrastructural analysis and mapping of targeting elements

Transcripts encoding the vasopressin precursor are located in axons and dendrites of rat hypothalamic magnocellular neurons. While the axonal vasopressin mRNA has been extensively characterized both at the biochemical and morphological level, little is known about those transcripts residing in dendrites of magnocellular neurons. As revealed by in situ hybridization at the electron microscopic level, the mRNA is located in proximal and distal dendritic segments and is exclusively confined to regions containing rough endoplasmic reticulum. These results suggest that dendrites of hypothalamic neurons may be capable of local precursor synthesis independent of that occurring in the cell somata. A heterologous system has been employed to define cis-acting elements within the vasopressin mRNA which may be involved in dendritic compartmentalization. Expression vector constructs consisting of the cytomegalovirus promoter coupled to the rat vasopressin cDNA have been injected into the cell nuclei of cultured neurons derived from embryonic rat superior cervical ganglia. Vector-encoded vasopressin transcripts were also sorted to dendrites of these neurons indicating that the molecular determinants of dendritic mRNA transport are not cell specific. Mapping of the targeting elements revealed two segments within the vasopressin mRNA that are able to confer dendritic compartmentalization to alpha-tubulin mRNA which is normally confined to the cell body.

Sequence analysis of a cDNA encoding an isotocin precursor and localization of the corresponding mRNA in the brain of the cartilaginous fish Torpedo marmorata

The nucleotide sequence of a cDNA encoding an isotocin hormone precursor has been elucidated by analyzing a lambda ZAPII library constructed using poly(A)+ RNA from the brain of the cartilaginous fish Torpedo marmorata. The sequence predicts a precursor of 126 amino acid residues that consists of a signal peptide, the isotocin moiety, and a neurophysin carrier protein. In contrast to other known fish isotocin precursor sequences, the Torpedo neurophysin moiety is not extended at its carboxy-terminus by a copeptin-like sequence. The T. marmorata isotocin precursor exhibits highest amino acid sequence identity (61%) to the toad mesotocin precursor. As demonstrated by in situ hybridization, the isotocin mRNA is present in neurons of the preoptic area of the Torpedo brain.

Distribution of somatostatin receptor subtype 1 mRNA in the developing cerebral hemispheres of the rat

Somatostatin (SST) is one of the major peptide transmitters in the mammalian central nervous system and also seems to exert specific functions during brain development. In contrast to ligand binding experiments, by which two pharmacologically different binding sites were characterized, molecular cloning techniques have led to the identification of at least five different receptor subtypes (SSTR1-5), which according to RNA blot analyses seem to be differentially distributed and regulated in the developing brain. In order to provide more precise data on the distribution of SSTR1 during ontogenesis, we have performed an in situ hybridization analysis, using a 35S-labelled RNA probe, in the developing rat cortex between embryonic day (E)12 and adulthood. Within the cortical plate, expression of SSTR1 gene was first detected in parallel with the establishment of the deep laminae V/VI at E16, thereby following the characteristic morphogenetic gradients of cortical plate construction. Thus, with the subsequent addition of cells along the radial dimension, e.g. the deposition of the supragranular neurons beyond E18, the hybridization signal spreads as an uniform homogenous band through the entire cortical plate, whereby silver grains reach their peak density around birth. Similar developmental gradients were observed along the lateromedial and frontooccipital dimension, whereby SSTR1 transcripts were detected near the frontal pole and the lateral cortical areas roughly 2 days before they appeared in the occipital and medial cortical anlage, respectively. From the initially homogenous distribution, two distinct SSTR1 mRNA-positive bands coextensive with laminae V/VI and II/III, respectively, and sparing lamina IV evolved during the first postnatal week, the grain density of which decreased during further postnatal development. Within the hippocampal formation, SSTR1 transcripts were initially observed at E18 in the subicular complex, and after birth also extending into the neighboring CA1 region. During the 1st and 2nd postnatal week, silver grains were observed over the pyramidal cell layer of CA2 and CA3 and as a faint supragranular band in the dentate gyrus. Similar to the isocortex, grain density decreased thereafter. Hypothetically, the pronounced temporospatial regulation of SSTR1 gene expression during brain development can be correlated with (1) the establishment and eventual reduction of transient cortical SSTergic neuron populations described for late pregnancy and early postnatal development and (2) a receptor subtype exchange during maturation as evidenced by the late (from postnatal day 7 onward) appearance of e.g. SSTR3.

Expression patterns of rat somatostatin receptor genes in pre- and postnatal brain and pituitary

The relative abundances of mRNAs encoding four different somatostatin receptors were examined using PCR techniques during postnatal development of the rat brain and hypophysis. In most tissues, somatostatin receptor 1 and 4 mRNAs are more abundant than those encoding somatostatin receptor 2 and 3. Transcript levels of somatostatin receptor subtype 4 are relatively high in the cortex, hippocampus, and striatum, those of subtype 1 in the cortex and brainstem, and those of subtype 3 in the cerebellum. In situ hybridization revealed the presence of significant amounts of somatostatin receptor 1 mRNA, as early as prenatal day 14, in the trigeminal ganglion and in the neuroepithelial layers surrounding the lateral, third, and fourth ventricles. In the developing cortex a morphological change in the sites of somatostatin receptor 1 gene expression occurs; mRNA is present superficially in the cortex at prenatal stages, appears in all layers shortly after birth, and in adult rats is restricted to the deep cortical layers. In the cerebellum, somatostatin receptor 1 mRNA levels are highest around birth, declining thereafter. In contrast, cerebellar somatostatin receptor 3 transcripts are absent at birth, become detectable around postnatal day 7, and reach a maximal level during maturation.

A novel rat serotonin receptor: primary structure, pharmacology, and expression pattern in distinct brain regions

Serotonin mediates various central and peripheral functions by its ability to bind to and activate a variety of receptors that belong to four pharmacologically defined classes termed 5-HT1 to 5-HT4. Using a polymerase chain reaction-derived probe, a clone, GPRFO, was isolated from a rat brain cDNA library. This cDNA encodes a putative G protein-coupled receptor that exhibits highest similarity to receptors for biogenic amines. RNA blot analysis indicated that the corresponding gene is expressed in the diencephalon. Consistent with the RNA blot data, GPRFO mRNA has been detected by in situ hybridization in the centrolateral, central medial, and intermediodorsal thalamic nuclei. Highest amounts of GPRFO mRNA, however, have been observed in a small area, i.e., the hippocampal rudiments and the stria longitudinalis. COS-7 cells transiently transfected with the GPRFO cDNA acquire saturable high-affinity binding sites for [3H]serotonin (KD = 41 nM). The pharmacological properties of the receptor differ from those of the known serotonin receptor subtypes, suggesting that the GPRFO cDNA encodes a novel serotonin receptor that is expressed in distinct rat brain regions.

Detection of growth hormone, prolactin and human beta-chorionic gonadotropin mRNA in growth hormone-secreting pituitary adenomas and in prolactin-secreting pituitary adenomas by in situ hybridization using a non-isotopic detection method

A non-isotopic in situ hybridization method with digoxigenin-labelled probes was used to examine growth hormone (GH), prolactin (PRL) and human beta-chorionic gonadotropin (beta-hCG(LH)) gene expression in 63 pituitary tumours in acromegaly and 20 adenomas in hyperprolactinaemia. hCG and LH were detected simultaneously because of the extensive homology (more than 90%) of their mRNA sequences (1). A comparison with former results obtained with 35S-labelled probes shows the value of the easier and faster non-isotopic method. Additionally, immunohistochemical data are included to give even more evidence for the synthesis of the respective hormones by the tumour cells. In all 63 adenomas in acromegaly, GH mRNA was revealed in 59 PRL mRNA and in 36 beta-hCG(LH) mRNA. A positive immunostaining for GH was found in all, for PRL in 40, and for beta-hCG(LH) in 34 adenomas. The comparison of the two in situ hybridization methods revealed no differences concerning GH mRNA detection, but not all tumours positive after non-isotopic PRL and beta-hCG(LH) mRNA detection showed signals with the radioactive method. Referring to the 20 PRL-secreting adenomas, PRL gene expression was demonstrable in all, GH mRNA in 12, and beta-hCG(LH) mRNA in 2 cases. Comparing the positive results of immunohistochemistry with those of in situ hybridization, correspondence was found in 19 cases for PRL, in 5 cases for GH and in no case for beta-hCG(LH).

Molecular cloning of a somatostatin-28 receptor and comparison of its expression pattern with that of a somatostatin-14 receptor in rat brain

The tetradecapeptide somatotropin-release inhibiting factor somatostatin-14 regulates the release of peptide hormones and also functions as neurotransmitter. The octacosapeptide somatostatin-28, the N-terminally extended form of somatostatin-14, shows similar biological activities yet with different potencies. Both peptides most likely function through distinct receptors. Here we report on the molecular and functional characterization of a somatostatin-28 receptor (SSR-28) cloned from a rat brain cDNA library. The nucleotide sequence contains an open reading frame for a protein of 428 amino acid residues with a predicted molecular mass of 47 kDa. Binding assays using radiolabeled somatostatin-14 and membranes from COS cells transfected with the cloned cDNA show that this receptor, SSR-28, has a higher binding affinity for somatostatin-28 (IC50 = 0.24 nM) than for somatostatin-14 (IC50 = 0.89 nM). RNA blot analysis reveals a 4.4-kilobase mRNA in rat cerebellum and at significantly lower abundance in other brain regions. In situ hybridization indicates that SSR-28 mRNA is present in the granular and Purkinje cell layers of the cerebellum and in the large cells of the hypoglossal nucleus of the brain stem. Signals for SSR-28 mRNA do not overlap with those of a previously cloned rat receptor that preferentially binds somatostatin-14 (SSR-14). SSR-14 mRNA is found in the medial cerebellar nucleus, horizontal limb of the diagonal band, various hypothalamic nuclei, and in layers IV and V of the cortex. In the rat cerebellum, SSR-14 and SSR-28 mRNAs are developmentally regulated; the levels of the former are highest around birth and levels of the latter are highest at the adult stage.

Detection of growth hormone, prolactin and human beta-chorionic gonadotropin messenger RNA in growth-hormone-secreting pituitary adenomas by in situ hybridization

In a series of 39 adenomas from patients with the clinical hyperfunction syndrome of acromegaly and in one from a case of prolactinoma we studied the mRNA expression of growth hormone (GH), prolactin (PRL) and beta-human chorionic gonadotropin (HCG) by using this technique of in situ hybridization (ISH). This technique allows the direct identification and localization of cells expressing mRNA and thus synthesizing the respective hormone. The aim of our study was to demonstrate the frequent co-expression of PRL mRNA and HCG mRNA in pituitary adenomas of acromegalic patients. Probes for ISH of the above-mentioned hormones were obtained by subcloning cDNA fragments into pGEM plasmids. Subsequent Sp6-polymerase catalysed in vitro transcription with 35S-CTP revealed radiolabelled single-stranded antisense RNA probes [the probe for beta HCG detects beta-luteinizing hormone (beta LH) simultaneously because of a sequence homology of 90%]. To localize the labelled hybrids, autoradiography was carried out. Light microscopical evaluation of the tissue sections demonstrated positive signals in all cases for GH, in 80% of cases for PRL and in 25% of cases for HCG [LH] mRNA. The comparison of mRNA content shown by ISH with immunocytochemical (ICC) hormone detection revealed that in all cases the detection of GH corresponded to GH mRNA content of the cells. For PRL and HCG [LH] positive mRNA detection (ISH) and negative hormone detection (ICC) occurred in some cases (PRL 17.5%; HCG [LH] 15%). In contrast, negative mRNA detection (ISH) and positive hormone content (ICC) was also demonstrated (PRL 5%; HCG [LH] 37.5%). The remaining adenomas showed both mRNA and the respective hormone, as well as negative ISH and ICC.

HGH, PRL and beta HCG/beta LH gene expression in clinically inactive pituitary adenomas detected by in situ hybridization

Within our surgical collection clinically inactive pituitary adenomas represent 30.7% of all pituitary tumours. To characterize their endocrine activity we studied 40 clinically inactive pituitary adenomas with in situ hybridization (ISH) using cRNA probes labelled with 35S encoding growth hormone (GH), prolactin (PRL) and chorionic gonadotrophin (beta HCG). No tumour was associated with clinical evidence of elevated hormone secretion. A mild hyperprolactinaemia not correlated with hormone or the mRNA content of the cells was interpreted to be incidental in 11 patients. By histological analysis, immunohistochemistry (IH) and electron microscopy the adenomas were diagnosed as small cell chromophobic (n = 16) and large cell chromophobic (n = 8) adenomas, and oncocytomas (n = 16). Gene expression of one or more hormones was identified by ISH in 18 of 40 adenomas in few cells. GH and PRL gene expression was rare (GH mRNA in 3 of 40 tumours and PRL mRNA in 8 of 40 tumours) whereas in 14 of 40 adenomas beta HCG/beta LH gene expression was identified in scattered cells. Five of 40 adenomas lacking hybridization signals revealed hormones by IH. The detection of mRNA was accompanied by positive immunostaining for the respective hormones in 72%. The combination of ISH and IH reveals good evidence that the hormones are synthesized in the tumours and not taken up from the serum and stored in the cells. The two methods used together permit a more precise analysis of tumour biology than each alone.

Axonal transport of neuropeptide encoding mRNAs within the hypothalamo-hypophyseal tract of rats

Hypothalamic vasopressin and oxytocin transcripts have been detected in the posterior pituitary suggesting either transcription of the respective genes in pituicytes or axonal mRNA transport from the hypothalamus to the nerve terminals of the posterior pituitary. The concept of axonal mRNA transport is supported firstly, by Northern blot and in situ hybridization analysis indicating that vasopressin and oxytocin mRNAs are also present in the neural stalk; secondly, by intron analysis and transcription run on experiments demonstrating the absence of primary vasopressin and oxytocin transcripts in non-neuronal cells of the posterior pituitary; thirdly, by embryonic developmental studies showing that appearance of vasopressin transcripts in the hypothalamus and the pituitary anlage is correlated. Furthermore, during axonal transport the respective mRNAs are subject to specific modification at the poly(A) tails.

In situ hybridization for different mRNA in GH-secreting and in inactive pituitary adenomas

In a series of 40 pituitary adenomas in acromegaly all tumors showed mRNA for GH by in situ hybridization (ISH). The signals were mostly very strong and found in more than 80% of adenoma cells by using frozen sections. In paraffin sections the number of positive cells and the intensity of signals are lower. Prolactin mRNA was found in 87% of adenomas. In 27% more than 80% of cells were marked. beta-HCGmRNA (with 90% hormology for LH-mRNA) was demonstrable in very sparse cells of 25% of adenomas. Comparing ISH with immunohistology (IH) we found a correlation between signals and hormone content in 100% of adenomas for GH, in 60% for Prolactin and in 10% for Gonadotropins. In 18% Prolactin mRNA but not the hormone was demonstrable and in 5% Prolactin was immunostained but no hybridization signals were detected. In a series of 40 clinically inactive adenomas sparse cells of three tumors expressed GHmRNA and two of these contained also the hormone, whereas in one adenoma GH but not GHmRNA was demonstrable. Prolactin mRNA was found in 8 adenomas. 7 of these also contained the hormone. In two cases Prolactin but not Prolactin mRNA was present. Beta-HCG(LH)mRNA and the respective hormones were shown in very sparse cells of 6 adenomas, whereas only beta-HCG(LH)-mRNA was found in 8 cases. The significance of the findings is discussed.

Differential polyadenylation of the mutant vasopressin mRNA during development of Brattleboro rats

In the normal (Wistar) rat vasopressin encoding mRNA first appears at embryonic day 15 as demonstrated by in situ hybridization of hypothalamic sections. In mutant (Brattleboro) rats, which possess a defective vasopressin gene with a single nucleotide deletion, the corresponding transcript is not detectable before fetal day 18. In both rat strains however expression of the structurally related oxytocin gene begins at fetal day 19. Whereas normal and mutant vasopressin encoding mRNAs are identical in size up to at least three weeks after birth, the corresponding transcripts from adult Brattleboro but not from normal rats are markedly larger. This increase in size is due to a longer stretch of poly(A) sequence as demonstrated by treatment of the respective mRNAs with RNase H and oligo(dT). Thus the mutant vasopressin gene transcript is subject to a cellular-specific differential polyadenylation process during development.

Expression of the oxytocin gene in the large cells of the bovine corpus luteum

In the bovine ovary there is a delay of 4-6 days between the observed maximum of oxytocin mRNA and the peak in the luteal levels of oxytocin nonapeptide. This implies a maturation process involving components of the post-translational processing pathway. In situ hybridization shows the oxytocin gene to be transcribed exclusively in the large cells of the corpus luteum at the beginning of the estrous cycle.

The stringent response to unacylated tRNA, energy-and temperature-downshift in Bacillus stearothermophilus

The response of the thermophile Bacillus stearothermophilus to inhibition of tRNA acylation, energy starvation and temperature downshift was characterized. We found that B. stearothermophilus, like other prokaryotic organisms, reacts with the so-called stringent response, which includes the accumulation of the unusual nucleotides guanosine 3',5' bis (diphosphate) [ppGpp] and guanosine 3'-diphosphate, 5'-tri-phosphate [pppGpp] and concomitantly the reduction of RNA synthesis and growth rate. The amount of (p)ppGpp formed depended on the cause of the stringent response: when tRNA acylation was inhibited (p)ppGpp synthesis was much higher than after energy starvation or temperature downshift whereas RNA synthesis was totally blocked in each case.

Stringent response of Bacillus stearothermophilus: evidence for the existence of two distinct guanosine 3',5'-polyphosphate synthetases

Bacillus stearothermophilus reacted to pseudomonic acid-induced inhibition of isoleucine-transfer ribonucleic acid (RNA) acylation and to energy downshift caused by alpha-methylglucoside addition with accumulation of guanosine 3',5'-polyphosphates [(p)ppGpp] and restriction of RNA synthesis. In vitro studies indicated that (p)ppGpp was synthesized by two different enzymes. One enzyme, (p)ppGpp synthetase I, was present in the ribosomal fraction, required the addition of a ribosome-messenger RNA-transfer RNA complex for activation, and was inhibited by tetracycline and thiostrepton. It is suggested that (p)ppGpp synthetase I is comparable to the relA gene product from Escherichia coli and is responsible for (p)ppGpp accumulation during amino acid starvation. The other enzyme, (p)ppGpp synthetase II, was found in the high-speed supernatant fraction (S100). It functioned independently of ribosomes, transfer RNA, and messenger RNA and was not inhibited by the above-mentioned antibiotics. (p)ppGpp synthetase II is thought to be responsible for (p)ppGpp accumulation during carbon source downshift. The two enzymes differ in their Km values for adenosine triphosphate (ATP):2mM ATP for synthetase I and 0.05 mM ATP for synthetase II. They also have different molecular weights: apparent Mr of 86,000 (+/- 5,000) for synthetase I and 74,000 (+/- 5,000) for synthetase II.