bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neutrophil Activation and Mediators of Inflammation in Chronic Venous Insufficiency
Authors: Smith Philip D. Coleridge 
Published: April 2003

The effect of venous hypertension on the state of activation of leucocytes has been investigated in patients with venous disease and control subjects. Leucocytes become ‘trapped’ in the circulation of the leg during periods of venous hypertension produced by sitting or standing. This is greater in the limbs of patients with chronic venous disease than controls. Studies of the plasma levels of neutrophil granule enzymes show that these are increased during periods of venous hypertension, suggesting that this causes activation of the neutrophils. Investigation of the leucocyte surface ligand CD11b shows that the more activated neutrophils and monocytes are sequestered during venous hypertension. Measurement of plasma levels of the soluble parts of the vascular (VCAM), intercellular (ICAM) and endothelial leucocyte (ELAM) adhesion molecules show that these are all elevated in patients with chronic venous disease compared to controls. Following 30 min of venous hypertension produced by standing, these levels are further increased. These data suggest that venous hypertension causes neutrophil and monocyte activation, which in turn causes injury to the endothelium. I believe that this may be the mechanism that initiates the pathological processes which lead to venous ulceration. It has recently been shown that the venotonic drug Daflon 500 mg (450 mg diosmin, 50 mg hesperidin, Servier, France) influences these processes. Surface expression of CD62L is reduced in neutrophils and monocytes, and plasma levels of soluble endothelial adhesion molecules are reduced. These observations may explain the anti-inflammatory effects of Daflon 500 mg.
Vertebrobasilar Strokes in Children
Authors: Al Tawari A. , Ouvrier R.A. , Steinberg A.W. , Grattan-Smith P. , Antony A. 
Published: April 2003

<i>Objectives:</i> This study describes the rare disorder of vertebrobasilar strokes in children and provides an assessment strategy to alert the clinician towards the possibility of this disorder. <i>Method:</i> A retrospective study of vertebrobasilar strokes over 20 years was conducted in the Neurology Department at the New Children’s Hospital, Sydney, Australia. <i>Results: </i>There were 6 males and 3 females between the ages of 18 months and 15 years. Frequently presenting features included headache, hemiparesis, ataxia and cranial nerve palsies. Aphasia occurred in 2 and afebrile seizures in 1 patient. Five patients had depressed consciousness extending to coma in 3. Etiological factors included trauma to the head or neck in 5, rheumatic endocarditis with artificial valve embolism in 1, brain stem encephalitis in 1 and undetermined etiology in 2. Diagnostic neuroimaging studies including MRI showed infarction in the territories of the occluded arteries. MRA showed occlusion of the vertebral artery and/or its branches in 5 patients, while the other 4 patients had involvement of the basilar artery and/or its branches. No abnormalities of blood coagulation were detected. Five patients were treated with anticoagulants. Acute hydrocephalus secondary to cerebellar infarction developed in 3 patients. Recurrent vertebrobasilar strokes were reported in 2 males, each of whom was treated surgically. There was 1 late death. Residual neurological deficits were seen in 5 patients and 3 made a complete recovery. <i>Conclusion:</i> Although this disorder is rare in pediatric patients, it is important to consider it in those children with appropriate neurological symptoms and signs.
Pharmacological Evidence that Neurotensin Mediates Prolactin- Induced Activation of Tuberoinfundibular Dopamine Neurons
Authors: Hentschel Kenneth , Cheung Sun , Moore Kenneth E. , Lookingland Keith J. 
Published: April 2003

The purpose of this study was to investigate the role of neurotensin (NT) receptors in mediating the stimulatory effects of prolactin on the activity of tuberoinfundibular dopamine (TIDA) neurons in male and female rats. TIDA neuronal activity was estimated by measuring concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) in terminals of these neurons in the median eminence (ME). Haloperidol activates TIDA neurons indirectly by blocking D<sub>2</sub> receptors on pituitary lactotropes, thereby increasing secretion of prolactin. Twelve hours after administration of haloperidol (1 mg/kg, s.c.), DOPAC concentrations in the ME were increased. Blockade of NT receptors with the selective antagonist SR-48692 had no effect per se on basal DOPAC concentrations in the ME but produced a dose-related (10–1,000 µg/kg, i.p.; 1 h) reversal of haloperidol-induced increases in ME DOPAC concentrations. In contrast, SR-48692 had no effect on either basal or haloperidol-induced increases in plasma prolactin. SR-48692 also blocked the stimulatory effects of prolactin (10 µg/rat, i.c.v.; 12 h) on ME DOPAC concentrations. SR-48692 was equally effective in blocking the stimulatory effects of haloperidol and prolactin on TIDA neurons in male and female rats. These results suggest that NT mediates the induced stimulatory effect of hyperprolactinemia on the activity of TIDA neurons in both males and females, whereas the tonic regulation of these neurons by prolactin in females occurs via an NT-independent mechanism.
Ovarian Steroids Modulate Responsiveness to Dopamine and Expression of G-Proteins in Lactotropes
Authors: Livingstone John D. , Lerant Anna , Freeman Marc E. 
Published: April 2003

The effects of chronic ovarian steroid treatment on the secretory activity of individual lactotropes and the mechanisms modulating their responsiveness to dopamine (DA) were studied. Female rats were ovariectomized (OVX) and implanted with Silastic capsules containing progesterone (P<sub>4</sub>), 17β), 17β-estradiol (E<sub>2</sub>) or both E<sub>2</sub> (E<sub>2</sub>+P<sub>4</sub>). Ten days after surgery, anterior pituitaries were enzymatically dispersed and the reverse hemolytic plaque assay (RHPA) was performed to assess the release of prolactin (PRL) from individual lactotropes. RHPA was combined with immunocytochemistry (ICC) for PRL, G<sub>αs</sub> or G<sub>iα3</sub>/G<sub>αo</sub> proteins. E<sub>2</sub> treatment alone or in combination with P<sub>4</sub> increased the percentage of immunoreactive lactotropes among anterior pituitary cells. Incidence of active (plaque-forming) lactotropes, however, was increased both in P<sub>4</sub>-, and E<sub>2</sub>-treated rats and E<sub>2</sub>+P<sub>4</sub> treatment increased it even further. While P<sub>4</sub> treatment did not affect the frequency distribution of lactotropes, both E<sub>2</sub> and E<sub>2</sub>+P<sub>4</sub> treatments increased the large plaque-forming lactotrope population. This increase was reflected by the significantly greater mean plaque areas of lactotropes from E<sub>2</sub>- and E<sub>2</sub>+P<sub>4</sub>-treated rats compared to OVX or P<sub>4</sub>-treated animals. The responsiveness of lactotropes to DA from P<sub>4</sub>-treated rats did not differ from that of OVX rats: thus challenge with 1 µ<i>M</i> DA inhibited the release of PRL, while 100 p<i>M</i> DA had no effect. E<sub>2</sub> and E<sub>2</sub>+P<sub>4</sub> treatments, however, profoundly changed the lactotrope’s responsiveness: challenge with 1 µ<i>M</i> DA had no effect and 100 p<i>M</i> DA resulted in moderate stimulation of PRL release in E<sub>2</sub>+P<sub>4</sub> rats. Double-label ICC revealed that ovarian steroid treatments did not affect the expression of G<sub>αs</sub> in lactotropes. The incidence of G<sub>iα3</sub>/G<sub>αo</sub>-immunoreactive lactotropes, however, decreased after E<sub>2</sub> treatment, alone or in combination with P<sub>4</sub>. Although expression of G<sub>αs</sub> was similar in all plaque-forming cells regardless of plaque size, lactotropes expressing G<sub>iα3</sub>/G<sub>αo</sub> were more likely to form small plaques in all treatment groups. These data suggest: (1) ovarian steroid treatment recruits quiescent lactotropes to release PRL; (2) E<sub>2</sub> treatment alone or in combination with P<sub>4</sub> increases the amount of PRL rleased by individual lactotropes; (3) E<sub>2</sub>-induced alterations in the frequency distribution and lactotrope responsiveness to DA may be due in part to a decreased expression of G<sub>iα3</sub>/G<sub>αo</sub>.
Diurnal Rhythmicity of Gonadotropin-Releasing Hormone Gene Expression in the Rat
Authors: Gore Andrea C. 
Published: April 2003

The release of the decapeptide gonadotropin-releasing hormone (GnRH) from neuroterminals in the median eminence varies depending upon the stage of development, time of day, reproductive season, and day of the ovarian cycle. With respect to the biosynthetic events responsible for such alterations in GnRH release, we have reported that increases in GnRH mRNA occur concomitantly with or precede the proestrous GnRH/LH surge in female rats, and the pubertal increase in GnRH. Because a hallmark of puberty is the development of nocturnal increases in gonadotropin/GnRH release, in the present study, we examined whether a rhythm in GnRH gene expression occurs that may be responsible for this rhythm of neurosecretion. Additionally, we extended the previous finding of diurnal rhythms of GnRH gene expression in cycling females to adult male rats. The mechanism for these changes, i.e. GnRH gene transcription, RNA processing or a posttranscriptional mechanisms was also elucidated. In experiment I, GnRH gene expression was measured in female rats at different stages of puberty [P25 (juvenile); ∼P37 (day of vaginal opening); and P45 (postpubertal)] at 10.00, 14.00, 18.00, 22.00, 2.00 and 6.00 h. GnRH mRNA levels increased significantly during pubertal development, independent of any changes in GnRH gene transcription or RNA processing, indicating a posttranscriptional mechanism. GnRH mRNA levels did not vary with time of day in these pubertal rats, indicating that the diurnal rhythm of GnRH release that develops during puberty is probably a posttranslational event. In experiment II, GnRH gene expression was measured in adult male rats at the same 4-hour intervals. GnRH mRNA levels varied significantly with time of day: they increased from 10.00 to 14.00 h, remained elevated through 22.00 h, then decreased significantly to the nadir at 10.00 h. The mechanism for these changes appears to involve processing or stability of the GnRH mRNA in the nucleus. These results indicate that GnRH mRNA levels are regulated differentially with time of day depending upon age and gender.
Delta Opiate Receptors Account for the Castration-Induced Unmasking of Gonadotropin-Releasing Hormone Binding Sites in the Rat Pituitary
Authors: Leblanc Pierre , L’Héritier Andrée , Kordon Claude 
Published: April 2003

Under control incubation conditions, gonadotropin-releasing hormone (GnRH) binds only a fraction of its receptors in rat-cultivated pituitary cells. Unmasking of the remaining receptors, which have been termed ‘cryptic’, requires drug- or peptide-induced protein kinase activation. Spontaneous masking however is not observed on pituitary cells sampled from castrated male rats, suggesting the presence of an intrinsic unmasking factor. Many endogenous factors could theoretically account for the effect. Here we attempted to identify the factor involved by taking advantage of their differential dependency upon second messengers and transduction cascades. Spontaneous unmasking of GnRH binding was found reversed by pertussis toxin (PTX), an inhibitor of α<sub>i</sub> and α<sub>o</sub> subunits of heterotrimeric G proteins, and by U73122, a phospholipase C (PLC) inhibitor. In contrast, desensitization of protein kinase C (PKC) or inhibition of tyrosine kinase by herbimycin were ineffective. Among endogenous pituitary factors able to unmask GnRH receptors in pituitary cells from normal male rats, as EGF, NPY or opiate peptides, only the latter were found to correspond to this transduction profile. In an attempt to characterize the pharmacology of opiate effects, naloxone (10 µ<i>M</i>), a poorly selective opiate antagonist, restored masking of GnRH binding in cells from castrates. Only the δ antagonist naltrindole (1 µ<i>M</i>) was able to mimick the action of naloxone. Conversely, when tested on cells from intact animals, morphine (10 µ<i>M</i>), as well as dslet (1 µ<i>M</i>) and met-ENK (10 n<i>M</i>), preferential δ agonists, but not dago and β-endorphin or U50488 H and dynorphin, respectively µ and ĸ agonists, were able to suppress masking. Among opioid peptides endogenous to the pituitary, only met-ENK was able to unmask cryptic receptors, an effect antagonized by naltrindole. We conclude that an opiate δ receptor subtype is endogenously activated in the pituitary of castrated male rats to prevent masking of GnRH binding.
Potentiation of Prolactin Secretion following Lactotrope Escape from Dopamine Action
Authors: del Mar Hernández María , García Ferreiro Rafael E. , García David E. , Hernández María Elena , Clapp Carmen , Martínez de la Escalera Gonzalo 
Published: April 2003

Hypothalamic dopamine (DA) tonically inhibits prolactin (PRL) release from the anterior pituitary gland. Transient escapes from this DA tone elicit a pronounced potentiation of the PRL-releasing action of secretagogues such as thyrotropin-releasing hormone (TRH). Previous evidence has suggested that modulation of Ca<sup>2+</sup> channels can be involved in this potentiation. With a lactotropic cell line (GH<sub>4</sub>C<sub>1</sub>) expressing human D<sub>2</sub>-DA receptors, we tested the hypothesis that a brief escape from the tonic inhibitory action of DA triggers a facilitation of Ca<sup>2+</sup> influx through Ca<sup>2+</sup> channels. We initially found that in these cells, DA effectively and reversibly inhibited PRL secretion, and reversibly enhanced an inwardly rectifying K<sup>+</sup> current. The effects of DA administration and withdrawal on Ca<sup>2+</sup> currents were examined using the patch-clamp technique in the whole-cell configuration and Ba<sup>2+</sup> as a divalent charge carrier through Ca<sup>2+</sup> channels. Macroscopic Ba<sup>2+</sup> currents were significantly decreased by short term (1–10 min) applications of DA (500 n<i>M</i>), which further declined following 24 h of constant exposure to DA. After DA removal, a biphasic facilitation of the density of Ba<sup>2+</sup> currents was observed. An initial 2-fold enhancement of conductance was detected between 10 and 40 min, followed by a second facilitation of the same magnitude observed 24 h after DA withdrawal. The present results directly demonstrate that dissociation of DA from D<sub>2</sub>-receptors expressed in GH<sub>4</sub>C<sub>1</sub> lactotrope cells causes an increase of high-voltage-activated Ca<sup>2+</sup> channel function, which may play an important role in the cross-talking amplification of endocrine cascades such as that involved in the TRH-induced PRL-release potentiating action of DA withdrawal.
Aging-Related Increased Expression of Inducible Nitric Oxide Synthase and Cytotoxicity Markers in Rat Hypothalamic Regions Associated with Male Reproductive Function
Authors: Ferrini Monica , Wang Christina , Swerdloff Ronald S. , Sinha Hikim Amiya P. , Rajfer Jacob , Gonzalez-Cadavid Nestor F. 
Published: April 2003

We have previously demonstrated that the inducible nitric oxide synthase (iNOS) protein and total NOS activity increase in the hypothalamus and other regions of the male rat brain during aging. We have now tested the hypothesis that increased iNOS results in excessive nitric oxide (NO) and peroxynitrite production, and leads to increased apoptosis in CNS cells, including the GnRH and oxytocin hypothalamic neurons involved in the control of male reproductive function. Young (3-month-old) and old (24-month-old) male Brown Norway rats (n = 6) were perfused with 4% formalin. Adjacent coronal paraffin-embedded sections (5 µm) of preoptic area (POA), supraoptic nucleus (SON), paraventricular nucleus (PVN), and arcuate nucleus (ARC) of the hypothalamus were immunostained with antibodies for iNOS, neuronal NOS (nNOS), and nitrotyrosine (a marker of peroxynitrite formation). The intensity of immunostaining was measured using a densitometric image analysis system. Apoptosis was determined by the TUNEL assay. Double immunofluorescence staining with confocal laser scanning microscopy was used for co-localization studies. A significant increase in the iNOS immunostaining measured as optical density (OD) was found in the old compared to the young animals (SON: 0.32 ± 0.02 vs. 0.23 ± 0.03, p < 0.05; PVN: 0.34 ± 0.03 vs. 0.07 ± 0.05, p < 0.001; POA: 0.18 ± 0.02 vs. 0.01 ± 0.02, p < 0.001). Aging did not affect nNOS expression. Nitrotyrosine was elevated in the hypothalamic regions of old compared to young rats (SON: 0.32 ± 0.05 vs. 0.10 ± 0.04, p < 0.05; PVN: 0.32 ± 0.04 vs. 0.13 ± 0.03, p < 0.01; POA: 0.72 ± 0.06 vs. 0.03 ± 0.003, p < 0.001). Increased nitrotyrosine was accompanied by an elevation of the apoptotic index in the old rats (SON: 11.01 ± 3.33 vs. 0.57 ± 0.50, p < 0.001; PVN: 3.08 ± 1.12 vs. 0.42 ± 0.32; POA: 6.60 ± 1.93 vs. 0.18 ± 0.17, p < 0.01; ARC: 0.001 ± 0.0001 vs. 4.33 ± 2.33). iNOS staining co-localized with GnRH and oxytocin staining. In conclusion: The aging-related iNOS increased expression in the hypothalamus of the male rat affects regions known to control the synthesis and release of GnRH (POA, ARC) and oxytocin (PVN, SON), and the factors regulating penile erection (POA, and PVN). These observations suggest that iNOS may play a role in the reduction in GnRH and oxytocin neuronal secretion resulting in reproductive dysfunctions such as lowered serum testosterone, hypospermatogenesis, and diminished copulatory function in the aging male animal.
Regulation of <i>Dexras1</i> Expression by Endogenous Steroids
Authors: Brogan Michelle D. , Behrend Ellen N. , Kemppainen Robert J. 
Published: April 2003

Dexras1, a newly identified member of the Ras superfamily of proteins, was discovered in AtT-20 corticotrope cells because its expression was induced in response to glucocorticoids (dexamethasone; Dex). As yet, the function of Dexras1 is unknown, but its rapid induction in response to glucocorticoids suggests the possibility that it may be involved in negative feedback regulation of corticotropin secretion. To better understand the control of<i> Dexras1</i> expression, possible effects of other steroid hormones on its expression were studied in both AtT-20 cells and in mouse pituitaries. AtT-20 cells were treated with each of 6 steroids [aldosterone, corticosterone (Cort), Dex, β-estradiol (E<sub>2</sub>), progesterone and testosterone] for 2 h. <i>Dexras1</i> expression was assessed using both reverse transcription polymerase chain reaction (RT-PCR) and Northern analysis. Expression of the gene was only induced in response to glucocorticoid treatment (Dex or Cort). The 6 steroids were also injected into mice, pituitaries were harvested and total RNA was obtained for RT-PCR analysis. Surprisingly, treatment with E<sub>2</sub>, not only injection of glucocorticoids, induced <i>Dexras1</i> expression in mouse pituitary. Other steroids were without effect. The results suggest that in AtT-20 corticotropes, <i>Dexras1</i> expression is only induced by glucocorticoid-type steroids. In pituitary glands of mice, the gene’s expression is also responsive to E<sub>2</sub>. We conclude that either <i>Dexras1</i> expression in corticotropes from normal mice is regulated differently from that in AtT-20 cells, or that <i>Dexras1</i> is also expressed in other pituitary cells than corticotropes.
The Clinical Significance of Tenascin-C Splice Variant Expression in Chondrosarcoma
Authors: Ghert Michelle A. , Jung Sung Taek , Qi Wen-ning , Harrelson John M. , Erickson Harold P. , Block Joel A. , Scully Sean P. 
Published: April 2003

<i>Objectives:</i> Tenascin-C (TNC) is an oligomeric glycoprotein of the extracellular matrix that is prominently expressed in malignant tumors. The purpose of this study was: (1) to determine the in vitro TNC splicing pattern in cultured human chondrocytes and chondrosarcoma cells, (2) to determine the in vivo TNC splicing pattern in clinical chondrosarcoma specimens, and (3) to perform survival analysis based on the TNC splicing pattern of the tumor specimens. <i>Methods:</i> Human articular chondrocytes and chondrosarcoma cells (cell line <i>JJ012</i>) were grown in a three-dimensional alginate bead system and harvested at two time points. Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was used to determine the in vitro TNC splicing pattern for the two cell types. Clinical chondrosarcoma specimens were obtained intra-operatively and underwent RT-PCR to determine the in vivo TNC splicing pattern. Specific immunohistochemical staining for the large TNC splice variant was performed on the clinical specimens. Survival analysis was used to determine the association between the specific TNC splicing pattern and survival. <i>Results:</i> The in vitro mRNA expression pattern of TNC in normal human articular chondrocytes was characterized by a high ratio of the small to the large splice variant (TNC<sub>small</sub>:TNC<sub>large</sub>), whereas the in vitro mRNA expression pattern for cultured chondrosarcoma cells was characterized by a low TNC<sub>small</sub>:TNC<sub>large</sub> ratio. Clinical chondrosarcoma specimens with a lower TNC<sub>small</sub>:TNC<sub>large</sub> ratio showed a trend towards decreased survival. The TNC splicing pattern of these specimens was verified through specific immunohistochemical staining for the large TNC isoform. <i>Conclusions:</i> The specific TNC splicing pattern may have clinical significance in chondrosarcoma. TNC expression may therefore play a future role in objecitve tumor grading and novel therapeutic approaches to this malignancy.