Prism adaptation in normal aging: slower adaptation rate and larger aftereffect

The effect of aging on prism adaptation, a motor learning paradigm, was evaluated. Different measures were obtained from a task consisting of throwing clay balls to a target in front of the subjects before, during, and after wearing prisms that deviate the visual field by several degrees. When performing the task without wearing the prisms, the aged subjects showed a larger hit variance, whereas the young subjects hit closer to the target. When donning the prisms, the aged group adapted more slowly than the controls, although after throwing all the balls both groups showed the same adaptation levels. After removing the prisms, the aged group showed a larger aftereffect. These findings suggest that the aftereffect requires the involvement of non-cognitive and cognitive processes and indicate that both adaptation and aftereffect are influenced by aging.

Stress and antibiotics alter luminal and wall-adhered microbiota and enhance the local expression of visceral sensory-related systems in mice

BACKGROUND

Stress leads to altered gastrointestinal neuro-immune responses. We characterized the interaction between stress and gut commensal microbiota and their role modulating colonic responses to stress, the induction of inflammation, the expression of sensory-related markers, and visceral sensitivity.

METHODS

C57BL/6N female mice were treated (7 days, PO) with non-absorbable-broad spectrum antibiotics (bacitracin/neomycin, 0.4 mg per mouse per day). Simultaneously, mice were subjected to a 1 h per day (7 days) session of psychological stress (water avoidance stress, WAS). Luminal and wall-adhered microbiota were characterized by fluorescent in situ hybridization. Cannabinoid receptors 1 and 2 (CB1/2), tryptophan hydroxylase 1 and 2 (TPH1/2), and inflammatory markers were quantified by reverse transcription-quantitative real-time PCR (RT-qPCR) and secretory-IgA (s-IgA) by ELISA. Visceral sensitivity was assessed after the intracolonic administration of capsaicin.

KEY RESULTS

Antibiotics did not affect the defecatory and endocrine responses to stress. However, antibiotics diminished by 2.5-folds total bacterial counts, induced a specific dysbiosis and favored bacterial wall adherence. Combining antibiotics and stress resulted in further reductions in bacterial counts and a dysbiosis, with enhanced bacterial wall adherence. Luminal s-IgA levels increased in dysbiotic mice. Nevertheless, no alterations consistent with the induction of colonic inflammation were observed. Dysbiosis upregulated CB2 expression and stress upregulated CB2 and TPH1 expression. Stress enhanced visceral pain-related responses, an effect prevented by antibiotic treatment.

CONCLUSIONS & INFERENCES

Manipulations of the commensal microbiota and the interaction host-microbiota are able to modulate the local expression of neuro-immune-endocrine systems within the colon, leading to a modulation of visceral sensitivity. These mechanisms might contribute to the pathogenic and protective roles of microbiota in gastrointestinal homeostasis.

New mutations in ZFPM2/FOG2 gene in tetralogy of Fallot and double outlet right ventricle

Conotruncal defects (CTDs) represent 15-20% of all congenital heart defects. Mutations in a number of genes have been associated with CTD in humans and animal models. We investigated the occurrence and the prevalence of GATA4, NKX2.5, ZFPM2/FOG2, GDF1, and ISLET1 gene mutations in a large cohort of individuals with CTD, including tetralogy of Fallot with or without pulmonary atresia (TOF, 178 patients), double outlet right ventricle (DORV, 13 patients), and truncus arteriosus (11 patients). Denaturing high-performance liquid chromatography (DHPLC) analysis followed by bidirectional sequencing disclosed no putative pathogenic mutation in GATA4, ISLET1, and GDF1 genes. Two novel (Ile227Val, Met544Ile) and one previously reported (Glu30Gly) possibly pathogenic missense variants were identified in the ZFPM2/FOG2 gene in 3 sporadic patients of 202 (1.5%) with CTD, including 1 of 178 (0.6%) with TOF and 2 of 13 (15.4%) with DORV. Mutation analysis also detected one known missense change (Arg25Cys) in NKX2.5 gene in two (1.1%) sporadic patients with TOF. These sequence alterations were found to be absent in 500 population-matched controls. In conclusion, the present results (i) indicate and confirm that mutations in the GATA4, GDF1, and ISLET1 genes are not major determinants in the pathogenesis of TOF, (ii) provide supportive evidence of an association between ZFPM2/FOG2 gene and TOF/DORV, and (iii) provide additional examples of the possible contribution of the Arg25Cys change in the NKX2.5 to a small number of TOF cases.

Endurance training in patients with chronic obstructive pulmonary disease: a comparison of high versus moderate intensity

PURPOSE

To create a maximum tolerated 45-minute aerobic training program for patients with chronic obstructive pulmonary disease (COPD) and to compare its outcomes with those of commonly prescribed moderate exercise.

DESIGN

Prospective, randomized trial.

SETTING

A work physiology laboratory.

PATIENTS AND METHODS

The maximum exercise intensities that 7 COPD patients could sustain for 45 minutes were determined on a bilevel exercise ergometer. The patients then exercised 45 minutes daily, 5 days a week for 6 weeks, working 2.03+/-0.4 kJ/kg per session. They were matched with 6 COPD patients who pushed an O2 cart for 45 minutes daily, 5 days a week for 6 weeks, working 1.44+/-.35 kJ/kg per session.

RESULTS

A 45 minute maximal regimen was established by alternating 1-minute peak exercise at peak VO2-levels with 4 minutes at the ventilatory anaerobic threshold or at 40% of peak VO2. Maximal bilevel training significantly decreased dyspnea at rest (p< or =.01) and the blood lactate level during submaximal exercise (p<.001), and increased peak VO2 and total physical work (p<.01), maximum inspiratory and expiratory pressures (p<.01), and grip and forearm strength and endurance (p<.01). The training also increased maximum voluntary ventilation while decreasing the ventilatory equivalent during exercise (p<.001). The O2 cart pushers significantly improved only on the 12-minute walk (p<.05).

CONCLUSIONS

A maximally intense anaerobic exercise program can be created for most COPD patients that can significantly improve both skeletal and respiratory muscle strength and endurance as well as dyspnea and physiologic parameters.

Glucagonlike peptide-1 (GLP-1) participation in ileal brake induced by intraluminal peptones in rat

The aim of this study was to determine the mechanisms implicated in the gastrointestinal inhibition induced by ovoalbumin hydrolysate infused intraluminally. We studied the site of action, the possible implication of GLP-1, and the nervous mechanisms involved. We prepared anesthetized Sprague-Dawley rats with strain gauges in the antrum, duodenum, and proximal jejunum and a catheter in the duodenum or ileum for peptone infusion. Both intraduodenal (N = 6) and intraileal (N = 5) infusion of ovoalbumin hydrolysate induced inhibition of spontaneous motor activity in the antrum, duodenum, and proximal jejunum. Duodenal inhibition induced by intraduodenal (N = 6) or intraileal (N = 6) infusion of ovoalbumin hydrolysate was reversed by intraarterial infusion of GLP-1 receptor antagonist, exendin (9-39) (3 x 10(-8) mol/kg/40 min). Finally, a combination of the adrenergic blockers phentolamine and propranolol (1 mg/kg, each; N = 7) completely blocked inhibitory gastrointestinal motor actions caused by intraduodenal infusion of ovoalbumin hydrolysate. This study demonstrates that peptone, intraluminally infused, participates in the regulation of gastrointestinal motility through stimulation of adrenergic pathways in anaesthetized rats. Moreover, these effects are partly mediated by GLP-1 secretion. The ileum seems to be the site of action, indicating a role of GLP-1 on the ileal break mechanism.

Spinal meningiomas: age-related features

OBJECTIVES

Spinal meningiomas mainly occur in old patients, with a remarkable female prevalence. This study investigates the different features between younger and older patients in an adult population (>18 years).

MATERIALS AND METHODS

A surgical series of 120 adult patients operated on for spinal meningiomas at the Neurosurgical Clinic of the "Federico II" University of Naples is reviewed. In this series 117 patients with a sporadic spinal meningioma were divided in two groups: group I including 30 patients (25.6%) younger than 50 years of age, group II including 87 patients (74.4%) older than 50 years. 3 patients had a spinal meningioma and neurofibromatosis. Several parameters, including sex, predisposing factors, tumor location and growth, histology, recurrences, proliferation index Ki-67 LI, and outcome, are considered and compared in the two age groups.

RESULTS

Group I showed an incidence of high cervical spine (C1-C4) meningiomas higher than group II (23.3% vs 3.4%, p=0.026) and lower rate of thoracic tumors (60% vs 82.7%, p=0.04). No significant differences of histological type and Ki-67 LI were found. Group I had 2 cases of atypical meningiomas (6.6% vs 0%, ns). Recurrences occurred in 6.6% of group I and 2.6% of group II, with no significance. In recurrent meningiomas values of Ki-67 LI were significantly higher than values in not recurrent meningiomas (p=0.0001), whereas no difference of estrogen and progesterone receptor expression was noted.

CONCLUSIONS

Younger adult patients with spinal meningiomas show not rare occurrence of NF (9%) and significantly higher incidence of high cervical and lower incidence of thoracic localizations with respect to the older patients. On the other hand, there are not significant differences of histology, Ki-67 LI and recurrence rate, excepting for a slight difference for atypical meningiomas.

Normal prism adaptation but reduced after-effect in basal ganglia disorders using a throwing task

Prism adaptation is a form of visuomotor learning in which the visual and motor systems need to be adjusted because a visual perturbation is produced by horizontally displacing prisms. Despite being known for over two centuries, the neuronal substrates of this phenomenon are not yet completely understood. In this article the possible role of the basal ganglia in this kind of learning was analysed through a study of Huntington's and Parkinson's disease patients. A throwing technique requiring the use of open loop feedback was used. The variables analysed were visuomotor performance, adaptation rate and magnitude, and the after-effect. The results clearly showed that both Huntington's and Parkinson's disease groups learned at the same rate as control subjects. In addition, despite having a disturbed visuomotor performance, both experimental groups showed the same adaptation magnitude as the control group. Finally, the after-effect, which is measured after removing the prisms, is reduced in both patients groups. This reduction leads to a disruption in the normal adaptation-after-effect correlation found in normal volunteers. These results suggest that basal ganglia are not involved in this type of open-looped visuomotor learning. The large number of patients studied as well as the similarity of the findings between both populations support this hypothesis. By contrast, there is an impairment in the after-effect on both basal ganglia patient populations. This impairment may be the result of the deterioration of the perceptual recalibration process involved in visuomotor learning.

Ultrasound as predictor of histologic subtypes linked to recurrence in basal cell carcinoma of the skin

BACKGROUND

Basal cell carcinoma (BCC) recurrences, especially in the facial region, represent a complex cosmetic problem. To date the possibility of predicting recurrence is supported solely by the histologic subtype.

OBJECTIVE

To evaluate the relationship between BCC histologic subtypes linked to high and low risk of recurrence and the presence of hyperechoic spots on sonography.

METHODS

Retrospective analysis of the pre-surgical ultrasound examinations of primary BCC tumours with visualization and counting of intra-tumoural hyperechoic spots. The data were then correlated with the corresponding histologic subtype.

RESULTS

Thirty one patients with histologically proven BCC were included in the study. Hyperechoic spots were detected in all cases and there was a positive, statistically significant association between hyperechoic spots count and high recurrence risk histologic subtypes. Higher hyperechoic spots count was found in the recurrence-prone micronodular, sclerosing variant and morpheiform BCC subtypes. Low risk and high risk of recurrence showed a significant difference on the mean hyperechoic spots count of 5.5 (range: 3-25) and 8 (4-81). A cut-off point ≥7 hyperechoic spots presented a sensitivity of 79% and specificity of 53% for predicting the high risk of recurrence subtypes.

CONCLUSION

The presence and count of hyperechoic spots within BCC lesions may help predicting the high risk of recurrence histologic subtypes.

Early clinical and neuroradiological worsening after radiotherapy and concomitant temozolomide in patients with glioblastoma: tumour progression or radionecrosis?

OBJECTIVES

This study investigates the diagnosis and management of patients with resected brain glioblastomas who presented early clinical and neuroradiological worsening after the completion of the Stupp protocol. Its aim is to discuss the occurrence of early radionecrosis.

METHODS

Fifty patients with brain glioblastoma treated by surgical resection and Stupp protocol were reviewed; 15 among them (30%) had early clinical and neuroradiological worsening at the 6-month follow-up. The MR spectroscopy and surgical findings of these patients are reviewed.

RESULTS

MR spectroscopy was in favour of tumour recurrence in 14 among 15 patients and showed radionecrosis in one. Among 10 patients who were reoperated on, 7 had histologically verified tumour recurrence or regrowth, whereas in 3 histopathology showed necrosis without evidence of tumour. The 7 patients with tumour progression had prevalence of focal neuroradiological signs (6/7) and a survival of 7.5-12 months (median survival 10 months). The 4 patients with early radionecrosis (including one patient who was not reoperated on) had clinical worsening with mental deterioration, confusion and ataxia, and MR spectroscopy positive for tumour recurrence in 3. Three were alive 24-30 months after the end of the radiotherapy, whereas one died at 40 months.

CONCLUSION

Early radionecrosis after the Stupp protocol is not a rare event due to the radiosensitization effect of temozolomide. This phenomenon may predict a durable response to radiotherapy. MR spectroscopy may simulate tumour recurrence. A correct diagnosis is necessary to avoid useless reoperations and incorrect withdrawal of temozolomide.

Mast cell stabilizer ketotifen [4-(1-methyl-4-piperidylidene)-4h-benzo[4,5]cyclohepta[1,2-b]thiophen-10(9H)-one fumarate] prevents mucosal mast cell hyperplasia and intestinal dysmotility in experimental Trichinella spiralis inflammation in the rat

Trichinella spiralis infection in rats induces hypermotility and an abnormal response to cholecystokinin (CCK) similar to motor disturbances observed in irritable bowel syndrome. Mast cell hyperplasia is also characteristic of this experimental model. The aim of our study was to correlate mast cell activity with the development of dysmotility and to demonstrate whether the mast cell stabilizer ketotifen [4-(1-methyl-4-piperidylidene)-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-10(9H)-one fumarate] could prevent the development of intestine hypermotility. Sprague-Dawley rats were infected with T. spiralis and, 5 days after infection, treated with the mast-cell stabilizer ketotifen (10 mg/kg/day). Twelve days after infection, intestinal spontaneous motor activity and response to CCK were evaluated by means of strain-gauge transducers. Immunohistochemistry for rat mast cell protease II (RMCPII), cyclooxygenase (COX)-2, and inducible nitric-oxide synthase (iNOS) was performed in intestinal specimens. In addition, RMCPII and myeloperoxidase were determined in serum. Infected control rats showed hypermotility, mast cell hyperplasia, increased RMCPII levels, increased myeloperoxidase, and overexpression of COX-2 and iNOS. In contrast, ketotifen-treated rats showed spontaneous intestinal motility and CCK response similar to the noninfected control rats. Mast cell hyperplasia and RMCPII were reduced in ketotifen-treated rats. Inflammatory parameters were less modified by ketotifen, but those animals that received the longest ketotifen treatment showed a slight amelioration in these parameters. These results indicate that mast cells are implicated in the development of hypermotility. The treatment with ketotifen prevented hypermotility and mast cell hyperplasia and diminished mucosal mast cell activity.

Factors determining gastrointestinal transit time of several markers in the domestic fowl

The aim of this study was to find out how marker characteristics could affect digestive transit time in Gallus gallus. One soluble marker, Cr-EDTA, and two insoluble markers, Cr2O3 and chromium-mordanted plant cells of two sizes, were used. Three- to six-week-old chickens were killed in series after the oral administration of the markers at intervals of 0, 0.5, 1, 2, 3, 5, 7, and 9 h. The amount of chromium in each digestive segment was determined by atomic absorption. There were some differences in the initial distribution of markers; whereas almost the total amount of the chromium-mordanted rice husk of the largest size was found in the crop at time 0, less than half of the Cr-EDTA was found. Marker emptying out of the crop was fast and not related to either the type or size. In contrast, the emptying rate of the gizzard depended on marker particle size. As far as the caeca were concerned, the ileocaecal junction allowed the passage of soluble Cr-EDTA whereas solid markers were impeded (Cr2O3) or not allowed to pass through at all (vegetable fibre of any size). It can be concluded that marker selection is of major importance to transit time studies in chickens, since its characteristics can determine transit time in an absolute way.

The siesta culture concept is not supported by the sleep habits of urban Mexican students

Evidence in support for the concept of the so-called 'siesta culture' is not well developed and has, to date, relied largely on qualitative anthropological data. Presumably such cultures are characterized by a strong tendency for daytime naps and daytime sleepiness, phenomena which may partially represent the effects of geographic, climatic or light conditions and/or cultural influences. In this study we surveyed the nocturnal sleep habits and daytime sleep tendencies of 577 Mexican college students residing in Mexico City (19 degrees N latitude). Results indicated a number of parallels between the reported sleep habits of these students and those reported from other cultures at latitudes far to the north (North America, Europe), such as longer sleep at the weekends, an association between snoring and daytime sleepiness and a lack of relationship between nocturnal sleep duration and the reported tendency to nap. There was some suggestion that these Mexican students may actually nap less when compared to other college student populations. Taken together, these results call into question what is meant by the concept of a 'siesta culture', at least in this urban, educated, upper social economic scale (SES) population, and suggest that future studies in equatorial regions be undertaken to further appreciate the role of climate, photoperiod and/or culture in the tendency for humans to nap during the day.

Astrocyte-specific expression of tyrosine hydroxylase after intracerebral gene transfer induces behavioral recovery in experimental parkinsonism

Parkinson's disease is a neurodegenerative disorder characterized by the depletion of dopamine in the caudate putamen. Dopamine replacement with levodopa, a precursor of the neurotransmitter, is presently the most common treatment for this disease. However, in an effort to obtain better therapeutic results, tissue or cells that synthesize catecholamines have been grafted into experimental animals and human patients. In this paper, we present a novel technique to express tyrosine hydroxylase (TH) in the host's own astrocytes. This procedure uses a transgene in which the expression of a TH cDNA is under the control of a glial fibrillary acidic protein (GFAP) promoter, which confers astrocyte-specific expression and also increases its activity in response to brain injury. The method was tested in a rat model of Parkinson's disease produced by lesioning the striatum with 6-hydroxydopamine. Following microinjection of the transgene into the denervated striatum as a DNA-liposome complex, expression of the transgene was detected by RT-PCR and TH protein was observed specifically in astrocytes by using double-labeling immunofluorescence for GFAP and TH coupled with laser confocal microscopy. Efficacy was demonstrated by significant behavioral recovery, as assessed by a decrease in the pharmacologically induced turning behavior generated by the unilateral denervation of the rat striatum. These results suggest this is a valuable technique to express molecules of therapeutic interest in the brain.

Cyclical upregulated iNOS and long-term downregulated nNOS are the bases for relapse and quiescent phases in a rat model of IBD

We previously reported that indomethacin induces a chronic intestinal inflammation in the rat where the cyclical characteristic phases of Crohn's disease are manifested with a few days' interval and lasting for several months: active phase (high inflammation, hypomotility, bacterial translocation) and reactive phase (low inflammation, hypermotility, no bacterial translocation). In this study, we investigated the possible role of both constitutive and inducible isoforms of nitric oxide (NO) synthase (NOS) and cyclooxygenase (COX) in the cyclicity of active and reactive phases in rats with chronic intestinal inflammation. Rats selected at either active or reactive phases and from 2 to 60 days after indomethacin treatment were used. mRNA expression of both constitutive and inducible NOS and COX isoforms in each phase was evaluated by RT-PCR and cellular enzyme localization by immunohistochemistry. The effects of different COX and NOS inhibitors on the intestinal motor activity were tested. mRNA expression of COX-1 was not modified by inflammation, whereas mRNA expression of neuronal NOS was reduced in all indomethacin-treated rats. In contrast, NOS and COX inducible forms showed a cyclical oscillation. mRNA expression and protein of both iNOS and COX-2 increased only during active phases. The intestinal hypomotility associated with active phases was turned into hypermotility after the administration of selective iNOS inhibitors. Sustained downregulation of constitutive NOS caused hypermotility, possibly as a defense mechanism. However, this reaction was masked during the active phases due to the inhibitory effects of NO resulting from the increased levels of the inducible NOS isoform.

Heterogeneity in electrical activity of the canine ileal circular muscle: interaction of two pacemakers

In cross-sectioned slabs from the muscularis externa or in the isolated circular muscle devoid of longitudinal muscle and myenteric plexus (MyP) of ileum, a slow wave, sigmoidal or triangular in shape, was recorded from microelectrode impalements near the deep muscular plexus (DMP) region in the whole-thickness preparation. From the MyP region of whole-thickness preparations, a slow wave which oscillated at a similar frequency (9-10 cycles min-1) was characterized by a fast upstroke and a square shape. Slow waves of mumixed pattern were recorded in the outer circular muscle (OCM) while triangular slow waves were present near the submucous plexus (SMP). In this preparation but not in isolated circular muscle, the inhibitory junction potentials (IJPs) produced by supramaximal electrical field stimulation triggered slow waves. The amplitudes (15-25 mV) of spontaneous and triggered slow waves (TSWs) were greatest in the MyP region, significantly so compared to those of DMP and SMP regions and to those in all regions of isolated circular muscle. Frequencies of slow waves recorded from the MyP and DMP were slightly but significantly higher than those recorded from either the OCM or the SMP or from all regions of isolated circular muscle. A 10-15 mV gradient in resting membrane potential (more hyperpolarized near MyP) existed across the intact (but not the isolated) circular muscle layer. Both types of slow waves, TSWs and IJPs were unaffected by muscarinic, adrenergic or tachykinergic blockade. We suggest that a MyP pacemaker network generated a plateau-type slow wave while a DMP one induced a triangular slow wave. Each source can function independently but the MyP network may dominate and entrain DMP slow waves.

Age influence on digestive transit time of particulate and soluble markers in broiler chickens

The gastrointestinal transit-time of two markers, Cr-mordanted bran, a solid marker, and Cr-EDTA, a soluble marker, have been studied in chickens (Gallus gallus) at 1, 2, and 3 wk of age. Mean retention time of the particular marker decreased as chicks grew. The excretion of Cr-EDTA took longer as birds grew; this soluble marker was retained in the ceca of the fowl. It was postulated that the ceca are not fully functional until total resorption of the yolk sac content occurs.

l-Theanine prevents carbon tetrachloride-induced liver fibrosis via inhibition of nuclear factor κB and down-regulation of transforming growth factor β and connective tissue growth factor

Here we evaluated the ability of L-theanine in preventing experimental hepatic cirrhosis and investigated the roles of nuclear factor-κB (NF-κB) activation as well as transforming growth factor β (TGF-β) and connective tissue growth factor (CTGF) regulation. Experimental hepatic cirrhosis was established by the administration of carbon tetrachloride (CCl4) to rats (0.4 g/kg, intraperitoneally, three times per week, for 8 weeks), and at the same time, adding L-theanine (8.0 mg/kg) to the drinking water. Rats had ad libitum access to water and food throughout the treatment period. CCl4 treatment promoted NF-κB activation and increased the expression of both TGF-β and CTGF. CCl4 increased the serum activities of alanine aminotransferase and γ-glutamyl transpeptidase and the degree of lipid peroxidation, and it also induced a decrease in the glutathione and glutathione disulfide ratio. L-Theanine prevented increased expression of NF-κB and down-regulated the pro-inflammatory (interleukin (IL)-1β and IL-6) and profibrotic (TGF-β and CTGF) cytokines. Furthermore, the levels of messenger RNA encoding these proteins decreased in agreement with the expression levels. L-Theanine promoted the expression of the anti-inflammatory cytokine IL-10 and the fibrolytic enzyme metalloproteinase-13. Liver hydroxyproline contents and histopathological analysis demonstrated the anti-fibrotic effect of l-theanine. In conclusion, L-theanine prevents CCl4-induced experimental hepatic cirrhosis in rats by blocking the main pro-inflammatory and pro-fibrogenic signals.

Study of the rate of passage of food with chromium-mordanted plant cells in chickens (Gallus gallus)

Thirty broilers 8-10 weeks old were used to study the rate of food passage in chickens. Wheat bran and rice husks of three different sizes: more than 2 mm, between 1 and 1.5 mm, and less than 0.5 mm, mordanted with chromium, were used as markers. The suitability of these markers to study the rate of food passage in chickens and the possible influence of the size and hardness of the particle on the retention time was the objective of this study. Both T1, the time of first appearance of the marker, and Tm, the mean retention time, have been evaluated. Tm was a better parameter than T1 for studying transit time. Tm was longer with the biggest particles, especially with rice husk. The gizzard, with its grinding activity and pylorus, a selector of particle size, seems to be the transit regulator for solid particles in chickens. No chromium was found in the caecal contents of any case.

Effects of cholecystokinin and gastrin on gastroduodenal motility and coordination in chickens

Cholecystokinin (CCK) has not been isolated from chicken gut yet and there has been no study on the effects of chicken gastrin (CG), the only gastrin/CCK peptide isolated from avian gut, on gastrointestinal motility. The main objective was to study the effects of CCK and CG on gastroduodenal motility and coordination in chickens. Electrodes for electromyography were implanted in the stomach and proximal and distal duodenum of 4 wk old chickens. Sulphated CCK-octapeptide (CCK8) (10(-10) to 10(-8) moles/kg), CCK-tetrapeptide (CCK4) (2 x 10(-10) to 2 x 10(-8) moles/kg) and CG (3 x 10(-10) to 10(-8) moles/kg) were given in a 10 min i.v. infusion. All these peptides induced a dose-dependent inhibition of gastric motility. CCK8 induced a duodenal hyperactivity whereas CCK4 and CG induced a duodenal inhibition. Neither the CCK-A receptor antagonist L364,718 nor the CCK-B receptor antagonist L365,260 (10(-9)-10(-7) moles/kg) antagonized CCK8 actions. From these results we suggest that the receptors mediating CCK effects are different from those of mammals. The site of action for these peptides is the same in the stomach whereas in the duodenum there are two different ones, one mediating excitation and the other inhibition. These results suggest a physiological role for CCK regulating gastroduodenal motility in birds.

Differentiation-dependent expression of transgenes in engineered astrocyte cell lines

The utility of transgenes for both basic and applied studies has been augmented by the recent advent of versions that can be regulated by the addition of suitable activators. However, still more convenient would be transgenes whose expression responded appropriately to endogenous signals. The promoter of the glial fibrillary acidic protein (GFAP) gene is a candidate for this role in the central nervous system (CNS) since the GFAP gene is specifically expressed in astrocytes in the CNS and its activity is upregulated in response to almost any CNS injury. As a feasibility study, we isolated a C6 rat glioma cell line stably transfected with a lacZ reporter gene driven by the gfa2 human GFAP promoter fragment. We find that the activity of the transgene indeed responds to an environmental signal, forskolin, that induces astrocyte-like differentiation of C6 cells. We also isolated a C6 line carrying a transgene in which the gfa2 promoter directs expression of a cDNA for tyrosine hydroxylase (TH), the rate-limiting enzyme for catecholamine synthesis. This transgene should be of considerable interest for gene therapy for Parkinson's disease. We show that in this cell line both TH mRNA and protein are upregulated by forskolin. Finally, we note that the growth rate of C6 cells is severely depressed by forskolin, suggesting that predifferentiation of these cells prior to implant may retard their tumor forming capacity, prolonging the time that they can be used in animal models in vivo.

Condition- and parasite-dependent expression of a male-like trait in a female bird

In many species, females display brightly coloured and elaborate traits similar to those that males use in intra- and inter-sexual selection processes. These female characters are sometimes related to fitness, and might function as secondary sexual characteristics that have evolved through sexual selection. Here, we used descriptive data from 674 females in 10 populations and an experimental removal of Trichostrongylus tenuis parasites in four populations, to examine the effects of season, age, condition, and parasites on the size of supra-orbital combs displayed by female red grouse Lagopus lagopus scoticus. We found that comb size (i) was greater during the breeding than the non-breeding season, (ii) was greater in adult than in young females, (iii) was positively correlated with body condition, and (iv) negatively correlated with parasite abundance. Experimentally, we showed that comb size increased proportionally to the number of worms removed after parasite dosing. Our findings provide a better understanding of proximate mechanisms behind the expression of a male-like trait in females, and we discuss its possible function as a female ornament.