bluuebunny/crossref_metadata_2025 huggingface dataset:
Disposition of amphotericin B in the isolated perfused rat liver
Authors: Hong Ying , Ramzan Iqbal , McLachlan Andrew J
Published: January 2004

The hepatic disposition and biliary excretion of amphotericin B were investigated in the isolated perfused rat liver (IPRL). Bolus dose of 50 μg, 99 μg and 198 μg amphotericin B in lipoprotein-free perfusate and 198 μg amphotericin B in perfusate with 1 μM high-density lipoprotein (HDL) or 1 μM low-density lipoprotein (LDL) were examined in the IPRL. Amphotericin B concentration in perfusate was measured using a validated HPLC assay. Amphotericin B was eliminated from the perfusate in a biexponential manner. The hepatic clearance (CLH) increased in proportion to the dose administered (0.27±0.05 mL min−1 at low dose, 0.54±0.23 mL min−1 at medium dose and 1.06±0.24 mL min−1 at high dose), indicating non-linear hepatic disposition of amphotericin B. The hepatic extraction ratio of amphotericin B was very low (0.066±0.015). Tissue-to-perfusion partition coefficient, calculated at 120 min, increased 1.5 fold from 9.8±1.7 at low dose to 15.9±6.4 at high dose, suggesting the significant uptake and extensive retention of amphotericin B in the liver. Biliary excretion made only minor contribution to amphotericin B elimination in the IPRL, representing around 1–3% of the dose administered. No metabolites were detected in perfusate, bile and liver samples. The hepatic disposition of amphotericin B was not affected by the presence of HDL and LDL in the perfusate. In conclusion, the hepatic disposition of amphotericin B demonstrates restrictive elimination and is concentration-dependent, consistent with carrier-mediated uptake, and lipoproteins do not influence amphotericin B hepatobiliary disposition.
Predicting the precipitation of poorly soluble weak bases upon entry in the small intestine
Authors: Kostewicz Edmund S , Wunderlich Martin , Brauns Ulrich , Becker Robert , Bock Thomas , Dressman Jennifer B
Published: January 2004

Solubility and dissolution relationships in the gastrointestinal tract can be critical for the oral bioavailability of poorly soluble drugs. In the case of poorly soluble weak bases, the possibility of drug precipitation upon entry into the small intestine may also affect the amount of drug available for uptake through the intestinal mucosa. To simulate the transfer out of the stomach into the intestine, a transfer model was devised, in which a solution of the drug in simulated gastric fluid is continuously pumped into a simulated intestinal fluid, and drug precipitation in the acceptor medium is examined via concentration–time measurements. The in-vitro precipitation of three poorly soluble weakly basic drugs, dipyridamole, BIBU 104 XX and BIMT 17 BS, was investigated. For all three, extensive supersaturation was achieved in the acceptor medium. Under simulated fasted-state conditions, precipitation occurred for all three compounds whereas under simulated fed-state conditions, the higher concentrations of bile components and the lower pH value in the acceptor medium inhibited precipitation at concentrations corresponding to usual doses in all cases. Comparison with pharmacokinetic data indicated that a combination of transfer model data with solubility and dissolution profiles should lead to better predictions of in-vivo behaviour of poorly soluble weak bases.
Evaluation of the impact of altered lipoprotein binding conditions on halofantrine induced QTc interval prolongation in an anaesthetized rabbit model
Authors: McIntosh Michelle P , Batey Andrew J , Coker Susan J , Porter Christopher J H , Charman William N
Published: January 2004

Halofantrine has been observed to cause QT interval prolongation in susceptible patients and the effect has most commonly been observed after post-prandial administration. Halofantrine-induced QT prolongation occurs in conjunction with a significant increase in plasma halofantrine concentrations and an increase in halofantrine association with post-prandial plasma lipoproteins. The increased association of halofantrine with post-prandial lipoproteins is accompanied by a marked change in drug distribution between the different plasma lipoprotein fractions. This study was designed to evaluate the putative role of myocardium-based lipoprotein receptor-mediated uptake of lipoproteins as a possible contributing factor to the observed effect of halofantrine on QT intervals. The extent of QT interval prolongation following intravenous halofantrine administration (10 mg kg−1) to normolipidaemic (fasted) or hyperlipidaemic (induced with Intralipid infusion) anaesthetized New Zealand White rabbits (n = 6) was determined, as was the distribution of halofantrine between the plasma lipoprotein classes. The results, however, were in contrast to the suggested hypothesis since the QT interval was reduced (and not increased) after halofantrine administration to hyperlipidaemic rabbits relative to fasted rabbits. Therefore, it is unlikely that lipoprotein-based uptake of halofantrine into the myocardium is a major contributor to the previously observed increase in QT prolongation after post-prandial administration of halofantrine.
Is nose-to-brain transport of drugs in man a reality?
Authors: Illum Lisbeth
Published: January 2004

The blood–brain barrier that segregates the brain interstitial fluid from the circulating blood provides an efficient barrier for the diffusion of most, especially polar, drugs from the blood to receptors in the central nervous system (CNS). Hence limitations are evident in the treatment of CNS diseases, such as Parkinson's and Alzheimer's diseases, especially exploiting neuropeptides and similar polar and large molecular weight drugs. In recent years interest has been expressed in the use of the nasal route for delivery of drugs to the brain, exploiting the olfactory pathway. A wealth of studies has reported proof of nose-to-brain delivery of a range of different drugs in animal models, such as the rat. Studies in man have mostly compared the pharmacological effects (e.g. brain functions) of nasally applied drugs with parenterally applied drugs and have shown a distinct indication of direct nose-to-brain transport. Recent studies in volunteers involving cerebrospinal fluid sampling, blood sampling and pharmacokinetic analysis after nasal, and in some instances parenteral administration of different drugs, have in my opinion confirmed the likely existence of a direct pathway from nose to brain.
Fibroblast heterogeneity: more than skin deep
Authors: Sorrell J. Michael , Caplan Arnold I.
Published: January 2004

Dermal fibroblasts are a dynamic and diverse population of cells whose functions in skin in many respects remain unknown. Normal adult human skin contains at least three distinct subpopulations of fibroblasts, which occupy unique niches in the dermis. Fibroblasts from each of these niches exhibit distinctive differences when cultured separately. Specific differences in fibroblast physiology are evident in papillary dermal fibroblasts, which reside in the superficial dermis, and reticular fibroblasts, which reside in the deep dermis. Both of these subpopulations of fibroblasts differ from the fibroblasts that are associated with hair follicles. Fibroblasts engage in fibroblast-epidermal interactions during hair development and in interfollicular regions of skin. They also play an important role in cutaneous wound repair and an ever-increasing role in bioengineering of skin. Bioengineered skin currently performs important roles in providing (1) a basic understanding of skin biology, (2) a vehicle for testing topically applied products and (3) a resource for skin replacement.
Ear candles: a triumph of ignorance over science
Authors: Ernst E.
Published: January 2004

Ear candles are hollow tubes coated in wax which are inserted into patients’ ears and then lit at the far end. The procedure is used as a complementary therapy for a wide range of conditions. A critical assessment of the evidence shows that its mode of action is implausible and demonstrably wrong. There are no data to suggest that it is effective for any condition. Furthermore, ear candles havebeen associated with ear injuries. The inescapable conclusion is that ear candles do more harm than good. Their use should be discouraged.
Cochlear implantation in chronic otitis media
Authors: Incesulu A. , Kocaturk S. , Vural M.
Published: January 2004

Patients with chronic otitis media (COM) may have profound sensorineural hearing loss either due to the disease process or secondary to a surgical procedure. Some patients who are candidates for cochlear implantation may have COM coincidentally. The patients in this group need special attention when cochlear implantation is applied. The aim of this study is to evaluate the potential risks and complications in patients with COM.

Cochlear implantation was performed in six patients with COM or an infected radical cavity and profound hearing loss. Five of them underwent a two-stage operation, and one had a single-stage operation. Cochlear implantation was performed in all patients without complications. The follow-up period was uneventful.

Although such patients have some potential risks, when certain surgical rules are followed very strictly cochlear implantation can be successfully performed in patients with COM.
Hearing loss associated with 35delG mutation in Connexin-26 (GJB2) gene: audiogram analysis
Authors: Salvinelli Fabrizio , Casale Manuele , D’Ascanio Luca , Firrisi Luca , Greco Fabio , Baldi Alfonso
Published: January 2004

35delG is the most common mutation in the Connexin-26 gene, representing a major cause of autosomal recessive hearing loss. The aim of this study was to evaluate the relationship between the audiological phenotype and the 35delG mutation in 64 Sicilians with non-syndromic deafness. Pure-tone audiometry and a screening for 35delG mutation were performed. Audiograms were evaluated according to the classification of Liu and Xu. Thirteen homozygotes and nine heterozygotes for the investigated mutation were found. Symmetrical hearing loss was significantly (p=0.008) more common in homozygous subjects than in those without the Connexin-26 mutation. Profound-severe hypoacusia was found in 92.3 per cent of 35delG homozygous, 22.3 per cent of heterozygous and 58.7 per cent of 35delG absent patients. Residual shape audiograms were more frequent in homozygotes. A molecular analysis for the 35delG mutation should be performed in cases of symmetric, severe-profound congenital hearing loss, as a genetic cause is probable in such cases.
Is the nasal tampon a suitable treatment for epistaxis in Accident & Emergency? A comparison of outcomes for ENT and A&E packed patients
Authors: Evans Andrew S. , Young David , Adamson Richard
Published: January 2004

This retrospective observational study aimed to establish the outcome for patients packed with a nasal tampon as first-line therapy for epistaxis in Accident & Emergency compared to those packed by ENT. During our study period, 189 admissions were treated with a nasal tampon as first-line therapy; 89 were inserted by ENT and 100 by A&E. A significantly higher number of patients packed by A&E required further treatment to control bleeding (p = 0.004; 95 per cent CI 7–34) than those in the group packed by ENT. A significantly greater proportion from the A&E group required additional cautery alone to control bleeding (p = 0.005; 95 per cent CI 5–30). We suggest that this may be due to inadequate initial assessment and inappropriate first-line therapy in the A&E department. It is recommended that ENT review patients prior to packing, in order to reduce the morbidity associated with multiple treatments.
Tracheoesophageal diversion versus total laryngectomy for intractable aspiration
Authors: Tomita Toshiki , Tanaka Kazuhito , Shinden Seiichi , Ogawa Kaoru
Published: January 2004

This study evaluates the outcome and surgical stress associated with surgery for intractable aspiration. A retrospective review was conducted to compare the results between tracheoesophageal diversion and total laryngectomy. The operative time, intra-operative bleeding, time until drain removal, feeding conditions and surgical complications were compared between the two groups. Of the 19 patients, 31.6 per cent underwent tracheoesophageal diversion and 68.4 per cent received total laryngectomy. The operative time and drain insertion periods were statistically shorter in the tracheoesophageal diversion group, while the amount of intra-operative blood loss was smaller in the tracheoesophageal diversion group. The complication rate and the feeding conditions before and after surgery for the two groups did not show anystatistically significant difference. Tracheoesophageal diversion was thus found to be a simple, safe, and reliable therapeutic modality for the control of intractable aspiration. Moreover, it induced less surgical stress than total laryngectomy.
Third and fourth branchial pouch anomalies
Authors: Rea P. A. , Hartley B. E. J. , Bailey C. M.
Published: January 2004

Congenital sinuses arising from the pyriform fossae are rare. They may present as neck cysts, recurrent neck abscesses, thyroiditis or neonatal stridor. Children typically undergo multiple surgical procedures
before the diagnosis is made.

We present our recent experience of five third-pouch sinuses and four fourth-pouch sinuses, including one bilateral case. The median age at presentation was four years. The mean number of operations prior to diagnosis was six (range 0-13), with a mean delay to diagnosis of six years. The diagnosis was made by barium swallow, by ultrasound, at pharyngoscopy or at open surgery. The median age at definitive surgery was 10 years. Definitive treatment involved complete excision of the sinus and neck mass in seven cases. Two sinuses were treated with endoscopicdiathermy to their internal opening.

Adoption of the correct nomenclature, diagnostic tools and operative requirements for these cases will help reduce the significant morbidity.
Acid reflux management: ENT perspective
Authors: Ahmad Ijaz , Batch A. J. G.
Published: January 2004

Otolaryngological manifestations of acid reflux include a wide range of pharyngeal and laryngeal symptoms; and the constellation of symptoms has been called laryngopharyngeal reflux.

This is a prospective study in a cohort of patients with various throat symptoms suggestive of laryngopharyngeal reflux (LPR) who underwent flexible oesophago-gastroscopy, as a principal investigation. The aims were to look at the most reliable symptom(s) and sign(s), the diagnostic role of flexible oesophago-gastroscopy and the treatment response in these patients.

The endoscopy score of 0 to 3 was based on endoscopic findings and the treatment response was measured from 0 to 100 per cent improvement of symptoms, as described by the patients.

There were a total of 303 patients, 174 females and 129 males with ages ranging from 19 to 88 years. Seventy-five per cent had had symptoms for more than a year. Fifteen per cent were smokers. Globus, voice change, sore throat, dysphagia and cough were the predominant symptoms. Most patients, however, presented with a complex of various other secondary symptoms.

The endoscopic findings were abnormal in 98 per cent of patients. Apart from the finding of non-specific hyperaemia, usually of the posterior larynx (13 per cent), lesions of the larynx and vocal folds were surprisingly uncommon.

Proton pump inhibitors (PPI) were prescribed in 90 per cent of patients. A total of 233 (76.8 per cent) responded to treatment. The improvement of symptoms ranged from 25 per cent in 36 (23 per cent), 50 per cent in 60 (20 per cent), 75 per cent in 59 (19 per cent) and 100 per centin 78 (26 per cent) patients.

Accumulative analysis of variance showed a significant difference between treatment responders and non-responders (p <0.04). In a logistic regression model patients with globus, voice change and gastric prolapse were more likely to respond to treatment (p <0.04).

It can be concluded that voice change, sore throat, globus and cough choking are the most reliable symptoms of laryngopharyngeal reflux. Voice change and globus symptoms can be of predictive value in terms of successful treatment response. Flexible oesophago-gastroscopy (FOG) isa simple, safe and reliable way of assessment in these cases and treatment with PPI can be effective in the majority of patients.
Concurrent surgeries in ENT: a cost-effective and safe approach in patients requiring multiple definitive procedures
Authors: Balraj Achamma , Kurien Mary , Job Anand
Published: January 2004

Treatment of the predisposing factors that are identified in the nose and throat in several ENT diseases is mandatory prior to the definitive management of the latter. When surgical management is indicated it has been traditional to use staged procedures. This study was undertaken to assess the role of concurrent surgical procedures in ENT and evaluate their cost-effectiveness compared to similar staged procedures. This was a retrospective case series of 100 consecutive patients undergoing concurrent and similar staged ENT surgical procedures. On analysis, it was noted that the average duration of surgery, anaesthesia and hospital stay was significantly less in the concurrent procedures group than in the staged procedures (2.35/3.1.hours; 3.05/3.30.hours and 2.5/6.5 days, respectively). The average hospital bill for the concurrent procedures was also lower than for the staged procedures. Hence, in patients requiring multiple ENT surgical procedures for definitive treatment, concurrent procedures are more cost-effective than staged procedures and should be considered the treatment of choice in a tertiary care centre.
Radical mastoidectomy cavity myiasis caused by Wohlfahrtia magnifica
Authors: Uzun Lokman , Cinar Fikret , Beder Levent Bekir , Aslan Turan , Altintas Kursat
Published: January 2004

In this article, a Wohlfahrtia magnifica otomyiasis case, a 31-year-old, non-mentally retarded patient who had undergone radical mastoidectomy previously is presented. Maggots in the radical mastoidectomy cavity were removed then topical treatment was applied. The maggots were identified as W. magnifica. In cases of myiasis, identification of larvae following direct extraction and application of preventative methods is essential.
Tuberculous pyomyositis of the temporal muscle in a nonimmunocompromised woman: diagnosis by sonography
Authors: Chu Chih-Kai , Yang Tsung-Lin , Tan Ching-Ting
Published: January 2004

Pyomyositis (PM) is an uncommon cause of acute bacterial infection occurring in skeletal muscle. This disease is rare in non-tropical areas, and PM caused by Mycobacterium is very rare in a non-immunocompromised person. The presence of temporal area swelling may lead to a differential diagnosis toward more common pathologies, such as a complication of mastoiditis or a neoplasm of the temporal area. This article describes a case of tuberculous pyomyositis in a non-immunocompromised woman, the diagnosis of which was confirmed by sonographically guided fine-needle aspiration.
Extraskeletal Ewing’s sarcoma of the larynx
Authors: Yang Yoon Soo , Hong Ki Hwan
Published: January 2004

Primitive neuroectodermal tumour/extraskeletal Ewing’s sarcoma (PNET/EES) is a rare disease of the head and neck region. We report a case of a 74-year-old man with a laryngeal Ewing’s sarcoma. This is the first reported case of extraskeletal Ewing’s sarcoma of the larynx in an elderly male patient. The patient was successfully treated with surgical resection and post-operative radiotherapy.
Extensive calvarial tuberculosis: rare complication of tuberculous mastoiditis
Authors: Thandar M. A. , Fagan J. J. , Garb M.
Published: January 2004

Tuberculous mastoiditis is a well-documented entity with decreasing incidence in recent years. Tuberculous osteitis of the skull is even rarer. The case of a 58-year-old male with tuberculous mastoiditis complicated by extensive tuberculous osteitis of the skullis presented. This case serves to demonstrate both the difficulty in establishing the diagnosis of tuberculosis and the potentially disastrous consequences of the disease.
Minimal Input Models for Sound Level and Reverberation Time Prediction in Enclosed Spaces
Authors: Dance Stephen. M.
Published: January 2004

Highly advanced computer models for the prediction of sound in rooms are now available. However, these tools are complex and require a skilled acoustician to use them effectively and hence there is a need for simpler models. A simple model needs to be accurate and quick to use, but most importantly should require a minimum amount of input data to construct the model. The resulting models are freely available to use and can be found at http://www.sbu.ac.uk/acogrp/steve.html .
Prefrontal Cortical–Ventral Striatal Interactions Involved in Affective Modulation of Attentional Performance: Implications for Corticostriatal Circuit Function
Authors: Christakou Anastasia , Robbins Trevor W. , Everitt Barry J.
Published: January 2004

Anatomically segregated systems linking the frontal cortex and the striatum are involved in various aspects of cognitive, affective, and motor processing. In this study, we examined the effects of combined unilateral lesions of the medial prefrontal cortex (mPFC) and the core subregion of the nucleus accumbens (AcbC) in opposite hemispheres (disconnection) on a continuous performance, visual attention test [five-choice serial reaction-time task (5CSRTT)]. The disconnection lesion produced a set of specific changes in performance of the 5CSRTT, resembling changes that followed bilateral AcbC lesions while, in addition, comprising a subset of the behavioral changes after bilateral mPFC lesions previously reported using the same task. Specifically, both mPFC/AcbC disconnection and bilateral AcbC lesions markedly affected aspects of response control related to affective feedback, as indexed by perseverative responding in the 5CSRTT. These effects were comparable, although not identical, to those in animals with either bilateral AcbC or mPFC/AcbC disconnection lesions. The mPFC/AcbC disconnection resulted in a behavioral profile largely distinct from that produced by disconnection of a similar circuit described previously, between the mPFC and the dorsomedial striatum, which were shown to form a functional network underlying aspects of visual attention and attention to action. This distinction provides an insight into the functional specialization of corticostriatal circuits in similar behavioral contexts.
Perceptual Correlates of Nociceptive Long-Term Potentiation and Long-Term Depression in Humans
Authors: Klein Thomas , Magerl Walter , Hopf Hanns-Christian , Sandkühler Jürgen , Treede Rolf-Detlef
Published: January 2004

Long-term potentiation (LTP) and long-term depression (LTD) of synaptic strength are ubiquitous mechanisms of synaptic plasticity, but their functional relevance in humans remains obscure. Here we report that a long-term increase in perceived pain to electrical test stimuli was induced by high-frequency electrical stimulation (HFS) (5 × 1 sec at 100 Hz) of peptidergic cutaneous afferents (27% above baseline, undiminished for >3 hr). In contrast, a long-term decrease in perceived pain (27% below baseline, undiminished for 1 hr) was induced by low-frequency stimulation (LFS) (17 min at 1 Hz). Pain testing with punctate mechanical probes (200 μm diameter) in skin adjacent to the HFS–LFS conditioning skin site revealed a marked twofold to threefold increase in pain sensitivity (secondary hyperalgesia, undiminished for >3 hr) after HFS but also a moderate secondary hyperalgesia (30% above baseline) after strong LFS. Additionally, HFS but not LFS caused pain to light tactile stimuli in adjacent skin (allodynia). In summary, HFS and LFS stimulus protocols that induce LTP or LTD in spinal nociceptive pathways in animal experiments led to similar LTP- and LTD-like changes in human pain perception (long-term hyperalgesia or hypoalgesia) mediated by the conditioned pathway. Additionally, secondary hyperalgesia and allodynia in adjacent skin induced by the HFS protocol and, to a minor extent, also by the LFS protocol, suggested that these perceptual changes encompassed an LTP-like heterosynaptic facilitation of adjacent nociceptive pathways by a hitherto unknown mechanism.
Semaphorin3A Inhibits Nerve Growth Factor-Induced Sprouting of Nociceptive Afferents in Adult Rat Spinal Cord
Authors: Tang Xiao-Qing , Tanelian Darrell L. , Smith George M.
Published: January 2004

Increased expression of NGF after spinal cord injury induces sprouting of primary nociceptive axons. Exogenous application of NGF also results in extensive sprouting of these axons and causes chronic pain in uninjured animals. During development, semaphorin3A is thought to act as a repulsive guidance cue for NGF-responsive nociceptive afferents, restricting their projections to the superficial dorsal horn. We investigated the ability of semaphorin3A to selectively reduce NGF-induced sprouting and neuropathic pain in adult rats. The chemorepulsive effect of virus-mediated semaphorin3A expression was shown to counteract the sprouting induced by NGF in a dose-dependent manner, bothin vitroand in adult rat spinal cords. Coexpression of semaphorin3A and NGF at moderate to low concentrations within the adult spinal cord reduced sprouting of calcitonin gene-related peptide and substance P-containing axons compared with GFP and NGF coexpression controls. At high expression levels of NGF, there was no difference in sprouting between the semaphorin3A-treated and control groups. The distribution of endogenous primary nociceptive afferents in the spinal cord appeared to be unaffected by semaphorin3A treatment in these experiments. Behavioral assessment shows that semaphorin3A coexpression with NGF led to decreased mechanical allodynia but no significant reductions in thermal hyperalgesia. These findings demonstrate directly that mature sensory afferents maintain their responsiveness to semaphorin3A, suggesting that this molecule might be used therapeutically to control aberrant sensory sprouting involved in pain or autonomic dysfunction.
Estrogen-Induced μ-Opioid Receptor Internalization in the Medial Preoptic Nucleus Is Mediated via Neuropeptide Y-Y1Receptor Activation in the Arcuate Nucleus of Female Rats
Authors: Mills Richard H. , Sohn Richard K. , Micevych Paul E
Published: January 2004

The endogenous peptides β-endorphin (β-END) and neuropeptide Y (NPY) have been implicated in regulating sexual receptivity. Both β-END and NPY systems are activated by estrogen and inhibit female sexual receptivity. The initial estrogen-induced sexual nonreceptivity is correlated with the activation and internalization of μ-opioid receptors (MORs), in the medial preoptic nucleus (MPN). Progesterone reverses the estrogen-induced activation/internalization of MOR and induces the sexual receptive behavior lordosis. To determine whether NPY and endogenous opioids interact, we tested the hypothesis that estrogen-induced MOR activation is mediated through NPY-Y1receptor (Y1R) activation. Retrograde tract tracing demonstrated Y1Ron β-END neurons that projected to the MPN. Sex steroid modulation of MOR in the MPN acts through NPY and the Y1R. Estradiol administration or intracerebroventricular injection of NPY activated/internalized Y1R in the arcuate nucleus and MOR in the MPN of ovariectomized (OVX) rats. Moreover, the selective Y1R agonist [Leu31, Pro34]-Neuropeptide Y (LPNY) internalized MOR in the MPN of OVX rats. The Y1R antagonist (Cys31, Nva34)-Neuropeptide Y (27–36)2prevented estrogen-induced Y1R and MOR activation/internalization. NPY reversed the progesterone blockade of estradiol-induced Y1R and MOR internalization in the arcuate nucleus and MPN, respectively. Behaviorally, LPNY inhibited estrogen plus progesterone-induced lordosis, and the MOR-selective antagonist D-Phe-Cys-Tyr-d-Trp-Orn-Thr-Pen-Thr amide reversed LPNY-induced inhibition of lordosis. These results suggest that a sequential sex steroid activation of NPY and MOR circuits regulates sexual receptivity.
Polymorphisms in the Taste Receptor Gene (Tas1r3) Region Are Associated with Saccharin Preference in 30 Mouse Strains
Authors: Reed D. R. , Li S. , Li X. , Huang L. , Tordoff M. G. , Starling-Roney R. , Taniguchi K. , West D. B. , Ohmen J. D. , Beauchamp G. K. , Bachmanov A. A.
Published: January 2004

The results of recent studies suggest that the mouseSac(saccharin preference) locus is identical to theTas1r3(taste receptor) gene. The goal of this study was to identifyTas1r3sequence variants associated with saccharin preference in a large number of inbred mouse strains. Initially, we sequenced ∼6.7 kb of theTas1r3gene and its flanking regions from six inbred mouse strains with high and low saccharin preference, including the strains in which theSacalleles were described originally (C57BL/6J,Sacb; DBA/2J,Sacd). Of the 89 sequence variants detected among these six strains, eight polymorphic sites were significantly associated with preferences for 1.6 mmsaccharin. Next, each of these eight variant sites were genotyped in 24 additional mouse strains. Analysis of the genotype–phenotype associations in all 30 strains showed the strongest association with saccharin preference at three sites: nucleotide (nt) –791 (3 bp insertion/deletion), nt +135 (Ser45Ser), and nt +179 (Ile60Thr). We measuredTas1r3gene expression, transcript size, and T1R3 immunoreactivity in the taste tissue of two inbred mouse strains with differentTas1r3haplotypes and saccharin preferences. The results of these experiments suggest that the polymorphisms associated with saccharin preference do not act by blocking gene expression, changing alternative splicing, or interfering with protein translation in taste tissue. The amino acid substitution (Ile60Thr) may influence the ability of the protein to form dimers or bind sweeteners. Here, we present data for future studies directed to experimentally confirm the function of these polymorphisms and highlight some of the difficulties of identifying specific DNA sequence variants that underlie quantitative trait loci.
Morphological Effects of Estrogen on Cholinergic NeuronsIn VitroInvolves Activation of Extracellular Signal-Regulated Kinases
Authors: Dominguez Reymundo , Jalali Cathy , de Lacalle Sonsoles
Published: January 2004

In the present study, we examined the ability of estrogen to enhance cholinergic neurite arborizationin vitroand identified the signal transduction cascade associated with this effect. Basal forebrain primordia collected from rat pups on postnatal day 1 were cultured for 2 weeks and then treated with 5 nm17β-estradiol for 24 hr. Cholinergic neurons were identified immunocytochemically with an antibody against the vesicular acetylcholine transporter and digitally photographed. Morphological analysis indicated that female cultures respond to estrogen treatment with an increase in total neurite length per neuron (4.5-fold over untreated controls) and in total branch segment number per neuron (2.3-fold over controls). In contrast, there was no change in total neurite length per neuron in male cultures, and we also observed a decrease in total branch segment number per neuron (0.5-fold below controls). Detailed histograms indicated that estrogen increases primary and secondary branch length and number and also increases terminal neuritic branches to the seventh order in female cultures. In a second set of experiments, we investigated the signal transduction cascade involved in this response, and found that an upstream extracellular signal-regulated kinase (ERK) inhibitor blocked the ability of estrogen to enhance outgrowth in female cultures. Our study provides strong evidence in support of the fact that the ERK pathway is required for estrogen-induced structural plasticity in the cholinergic system of female rats. Understanding the intracellular processes that underlie the response of cholinergic neurons to estrogen provides a necessary step in elucidating how cholinergic neurons can be particularly susceptible to degeneration in postmenopausal women.
EnhancedIn VitroMidbrain Dopamine Neuron Differentiation, Dopaminergic Function, Neurite Outgrowth, and 1-Methyl-4-Phenylpyridium Resistance in Mouse Embryonic Stem Cells Overexpressing Bcl-XL
Authors: Shim Jae-Won , Koh Hyun-Chul , Chang Mi-Yoon , Roh Eun , Choi Cha-Yong , Oh Young J. , Son Hyeon , Lee Yong-Sung , Studer Lorenz , Lee Sang-Hun
Published: January 2004

Embryonic stem (ES) cells provide a potentially unlimited source of specialized cells for regenerative medicine. The ease of inducing stable genetic modifications in ES cells allows forin vitromanipulations to enhance differentiation into specific cell types and to optimizein vivofunction of differentiated progeny in animal models of disease. We have generated mouse ES cells that constitutively express Bcl-XL, an antiapoptotic protein of Bcl-2 family.In vitrodifferentiation of Bcl-XL overexpressing ES (Bcl-ES) cells resulted in higher expression of genes related to midbrain dopamine (DA) neuron development and increased the number of ES-derived neurons expressing midbrain DA markers compared with differentiation of wild-type ES cells. Moreover, DA neurons derived from Bcl-ES cells were less susceptible to 1-methyl-4-phenylpyridium, a neurotoxin for DA neurons. On transplantation into parkinsonian rats, the Bcl-ES-derived DA neurons exhibited more extensive fiber outgrowth and led to a more pronounced reversal of behavioral symptoms than wild-type ES-derived DA neurons. These data suggest a role for Bcl-XL duringin vitromidbrain DA neuron differentiation and provide an improved system for cell transplantation in a preclinical animal model of Parkinson's disease.
Morphological and Physiological Features of a Set of Spinal Substantia Gelatinosa Neurons Defined by Green Fluorescent Protein Expression
Authors: Hantman Adam W. , van den Pol Anthony N. , Perl Edward R.
Published: January 2004

The spinal substantia gelatinosa (SG) is known to be involved in the manipulation of nociceptive and thermal primary afferent input; however, the interrelationships of its neuronal components are poorly understood. As a step toward expanding understanding, we took a relatively unique approach by concentrating on a set of SG neurons selectively labeled by green fluorescent protein (GFP) in a transgenic mouse. These GFP-expressing SG neurons prove to have homogenous morphological and electrophysiological properties, are systematically spaced in the SG, contain GABA, receive C-fiber primary afferent input, and upregulate c-Fos protein in response to noxious stimuli. Together, the properties established for these GFP-labeled neurons are consistent with a modular SG organization in which afferent activity related to nociception or other C-fiber signaling are subject to integration/modulation by repeating, similar circuits of neurons.
Action Potential Timing Determines Dendritic Calcium during Striatal Up-States
Authors: Kerr Jason N. D. , Plenz Dietmar
Published: January 2004

Up-states represent a key feature of synaptic integration in cortex and striatum that involves activation of many synaptic inputs. In the striatum, the sparse firing and tight control of action potential timing is in contrast to the large intracellular membrane potential depolarizations observed during the up-state. One hallmark of striatal spiny projection neurons is the delay to action potential generation in both up-states and suprathreshold depolarization by somatic current injection. By studying somatic and dendritic intracellular calcium ([Ca2+]i) transients during spontaneous up-states in cortex–striatum–substantia nigra organotypic cultures, we show that the delay between up-state onset and action potential generation determines dendritic peak [Ca2+]i. Peak [Ca2+]ifrom single action potentials reached maximum values when action potentials were close to up-state onset and sharply decayed to near subthreshold up-state [Ca2+] levels as a function of time (τ = 47 ± 26 msec for tertiary dendrite). Similarly, a precisely timed action potential elicited during subthreshold up-states through somatic current injection established that the delay between up-state onset and action potential generation is the critical variable that controls peak [Ca2+]i. Blocking NMDA channels internally with high intracellular Mg2+([Mg2+]i) (10 mm) abolished the dependency of peak [Ca2+]ion action potential timing during spontaneous up-states. Finally, high [Mg2+]ispecifically blocked [Ca2+]itransients that resulted from local NMDA application in conjunction with backpropagating action potentials. We conclude that precisely timed, single action potentials during striatal up-states control peak dendritic calcium levels. We suggest that this mechanism might play an important role in synaptic plasticity of the corticostriatal pathway.
A Circadian Rhythm in the Expression of PERIOD2 Protein Reveals a Novel SCN-Controlled Oscillator in the Oval Nucleus of the Bed Nucleus of the Stria Terminalis
Authors: Amir Shimon , Lamont Elaine Waddington , Robinson Barry , Stewart Jane
Published: January 2004

Circadian rhythms in mammals are regulated not only globally by the master clock in the suprachiasmatic nucleus (SCN), but also locally by widely distributed populations of clock cells in the brain and periphery that control tissue-specific rhythmic outputs. Here we show that the oval nucleus of the bed nucleus of the stria terminalis (BNST-OV) exhibits a robust circadian rhythm in expression of the Period2 (PER2) clock protein. PER2 expression is rhythmic in the BNST-OV in rats housed under a light/dark cycle or in constant darkness, in blind rats, and in mice, and is in perfect synchrony with the PER2 rhythm of the SCN. Constant light or bilateral SCN lesions abolish the rhythm of PER2 in the BNST-OV. Large abrupt shifts in the light schedule transiently uncouple the BNST-OV rhythm from that of the SCN. Re-entrainment of the PER2 rhythm is faster in the SCN than in the BNST-OV, and it is faster after a delay than an advance shift. Bilateral adrenalectomy blunts the PER2 rhythm in the BNST-OV. Thus, the BNST-OV contains circadian clock cells that normally oscillate in synchrony with the SCN, but these cells appear to require both input from the SCN and circulating glucocorticoids to maintain their circadian oscillation. Taken together with what is known about the functional organization of the connections of the BNST-OV with systems of the brain involved in stress and motivational processes, these findings place BNST-OV oscillators in a position to influence specific physiological and behavioral rhythms downstream from the SCN clock.
Production of 5α-Reduced Neurosteroids Is Developmentally Regulated and Shapes GABAAMiniature IPSCs in Lamina II of the Spinal Cord
Authors: Keller A. Florence , Breton Jean-Didier , Schlichter Rémy , Poisbeau Pierrick
Published: January 2004

In lamina II of the spinal dorsal horn, synaptic inhibition mediated by ionotropic GABAAand glycine receptors contributes to the integration of peripheral nociceptive messages. Whole-cell patch-clamp recordings were performed from lamina II neurons in spinal cord slices to study the properties of miniature IPSCs (mIPSCs) mediated by activation of GABAAand glycine receptors in immature (<30 d) and adult rats. Blockade of neurosteroidogenesis by 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinoline carboxamide (PK11195), an inhibitor of the peripheral benzodiazepine receptor (PBR), or finasteride, which blocks 5α-reductase, accelerated the decay kinetics of GABAAreceptor-mediated mIPSCs in immature, but not in adult animals. Glycine receptor-mediated mIPSCs remained unaffected under these conditions. These results suggest the presence of a tonic production of 5α-reduced neurosteroids in young rats that confers slow decay kinetics to GABAAmIPSCs. At all of the ages, selective stimulation of PBR by diazepam in the presence of flumazenil prolonged GABAAmIPSCs in a PK11195- and finasteride-sensitive manner. This condition also increased the proportion of mixed GABAA/glycine mIPSCs in the immature animals and led to the reappearance of mixed GABAA/glycine mIPSCs in the adult. Our results might point to an original mechanism by which the strength of synaptic inhibition can be adjusted locally in the CNS during development and under physiological and/or pathological conditions by controlling the synthesis of endogenous 5α-reduced neurosteroids.
Postsynaptic Density 95 controls AMPA Receptor Incorporation during Long-Term Potentiation and Experience-Driven Synaptic Plasticity
Authors: Ehrlich Ingrid , Malinow Roberto
Published: January 2004

The regulated delivery of AMPA-type glutamate receptors (AMPARs) to synapses is an important mechanism underlying synaptic plasticity. Here, we ask whether the synaptic scaffolding protein PSD-95 (postsynaptic density 95) participates in AMPAR incorporation during two forms of synaptic plasticity. In hippocampal slice cultures, the expression of PSD-95–green fluorescent protein (PSD-95–GFP) increases AMPAR currents by selectively delivering glutamate receptor 1 (GluR1)-containing receptors to synapses, thus mimicking long-term potentiation (LTP). Mutational analysis shows that the N terminal of PSD-95 including the first two PDZ [PSD-95/Discs large (Dlg)/zona occludens-1 (ZO-1)] domains is necessary and sufficient to mediate this effect. Further supporting a role in synaptic plasticity, wild-type PSD-95 occludes LTP and dominant negative forms block LTP. Moreover, we demonstrate that PSD-95 also participates in AMPAR delivery during experience-driven plasticityin vivo. In the barrel cortex from experience-deprived animals, the expression of PSD-95–GFP selectively increases AMPAR currents, mimicking experience-driven plasticity. In nondeprived animals, PSD-95–GFP produces no additional potentiation, indicating common mechanisms between PSD-95-mediated potentiation and experience-driven synaptic strengthening. A dominant negative form of PSD-95 blocks experience-driven potentiation of synapses. Pharmacological analysis in slice cultures reveals that PSD-95 acts downstream of other signaling pathways involved in LTP. We conclude that PSD-95 controls activity-dependent AMPAR incorporation at synapses via PDZ interactions not only during LTPin vitrobut also during experience-driven synaptic strengthening by natural stimuliin vivo.
Induction of superovulation by inhibin vaccine in cyclic guinea-pigs
Authors: Shi F , Ozawa M , Komura H , Watanabe G , Tsonis CG , Suzuki AK , Taya K
Published: January 2004

Experiments were conducted to determine whether neutralizing endogenous inhibin affects follicular development and ovulation rate in guinea-pigs. Eighteen female guinea-pigs bearing 4 week progesterone implants were divided into three groups. At 1 week after removal of the progesterone implants, the animals were given a s.c. injection of 1 ml placebo (saline in oil emulsion; control), or 25 or 50 micrograms inhibin vaccine three times at 4 week intervals. Blood samples were collected once a week throughout the experiment for measuring inhibin antibody titres. After the third injection of inhibin vaccine, blood samples and ovaries were collected on the morning of day 8 after the day of oestrus. Inhibin vaccine increased the ovulation rate in a dose-dependent manner (placebo: 4.2 +/- 0.4; 25 micrograms inhibin vaccine: 6.2 +/- 0.9; 50 micrograms inhibin vaccine: 9.8 +/- 0.9) without any effects on the duration of the oestrous cycle. The results also showed that active immunization against inhibin increased the number of atretic follicles of 300-399 microns in diameter on day 8 after ovulation. The present study is the first to show that the active immunization against inhibin may be a useful method for inducing multiple ovulation in guinea-pigs.
Reproductive hormone profiles in mares during the autumn transition as determined by collection of jugular blood at 6 h intervals throughout ovulatory and anovulatory cycles
Authors: Irvine CH , Alexander SL , McKinnon AO
Published: January 2004

The aim was to define precisely the FSH secretion pattern in mares during the two ovulatory cycles before, and for 24 days after, the last ovulation of the season and to compare this with the profiles of other reproductive hormones and follicular growth to identify changes which may lead to the termination of follicular cycles. Jugular blood was collected every 6 h from ten light horse mares for 6 weeks in autumn. Samples were assayed for FSH, LH, prolactin, inhibin, oestrone conjugates and progesterone. Luteolysis occurred earlier and periovulatory oestrone, but not inhibin, concentrations were significantly lower in the last than in the second to last cycles. In ovulatory and anovulatory cycles, daily mean FSH concentrations were low at the expected time of ovulation and high between days 9 and 11 (day 0 = ovulation), which were usually after luteolysis. However, the periovulatory FSH nadir was prolonged in the last compared with the second to last cycles, and the difference between peak and trough values was not significant in anovulatory cycles. Between day 5 and day 8, the FSH interpulse interval was approximately 2 days, and did not vary in successive cycles. The LH profile also showed progressive changes as mares entered acyclicity; the surge terminated sooner in the last than in the second to last cycles, and failed to occur when expected in acyclicity. Sporadic prolactin pulses occurred at luteolysis in a similar proportion of ovulatory and anovulatory cycles. These results indicate that inadequate gonadotrophin stimulation in early dioestrus may be a critical event leading to suboptimal follicular and luteal development, and eventually acyclicity. Moreover, the time relationships amongst changes in pituitary and ovarian hormones and follicular growth become increasingly disrupted during the autumn transition, which may contribute to the cessation of cyclicity.
Effect of nitric oxide synthase inhibitors on ovum transport and oviductal smooth muscle activity in the rat oviduct
Authors: Perez Martinez S , Viggiano M , Franchi AM , Herrero MB , Ortiz ME , Gimeno MF , Villalon M
Published: January 2004

The effect of the inhibition of nitric oxide synthase (NOS) on ovum transport and oviductal motility in rats was investigated. Three different NOS inhibitors were injected into the ovarian bursa at oestrus or day 3 of pregnancy. Oviducts and uteri were flushed 24 h later and the presence of ova was recorded. In oestrous and pregnant rats, treatment resulted in accelerated egg transport, as shown by a decrease in the number of ova present in the oviducts. In cyclic rats, intrabursal injection of 1 mg kg-1 of either N-monomethyl-L-arginine (L-NMMA) or N omega nitro-L-arginine methyl ester (L-NAME) elicited a 30% reduction in the number of ova present in the oviducts, whereas in pregnant animals, the same dose of L-NMMA produced a reduction of 40%. Simultaneous administration of the NO donor spermine NONOate (5 mg kg-1) completely reversed the effect of L-NMMA. Tubal motility was assessed by microsphere displacement analysis within the oviduct. Surrogate ova were transferred to the oviductal lumen at oestrus and 24 h later the effect of intraoviductal injection of 1 microgram L-NMMA or vehicle was assessed. The microspheres in the isthmus showed an oscillating motion, and periods in which movement was not detectable. However, L-NMMA treatment produced a 3.6-fold increase in the maximum instant velocities and a significant reduction in the resting periods of the microspheres compared with the control group (P < 0.001). These results provide evidence that NO inhibition increases tubal motility that results in accelerated ovum transport, and indicate that NO could act as a paracrine signal between different layers of the oviductal wall, providing a role for endogenous NO in regulation of tubal function.