bluuebunny/crossref_metadata_2025 huggingface dataset:
Matching and Symmetry in the Frequency Recognition Curve of the Poison Frog Epipedobates trivittatus
Authors: Rojas Bibiana , Amézquita Adolfo , Delgadillo Alexandra
Published: March 2006

In territorial species, males use signals to advertise territory ownership to other males. In species with acoustic communication, masking interference by heterospecific signals may impede male–male communication and affect the reproductive success of males. Frogs are thought to minimize masking interference by using species‐specific frequency channels for communication. For this strategy to work, a frequency match is expected between the advertisement call and the auditory sensitivity. A previous field study on the Amazonian frog Epipedobates femoralis supported this prediction, but also revealed an asymmetric decrease in the probability of male reaction towards synthetic calls. That males of E. femoralis reacted less towards low‐frequency (compared with high‐frequency) calls was interpreted as a mechanism that reduces masking interference by E. trivittatus, a species calling within a lower, partially overlapping, frequency range. If this hypothesis holds, then males of E. trivittatus should exhibit the opposite asymmetry pattern, i.e. react less towards high‐frequency (compared with low‐frequency) calls. We tested this prediction by conducting 25 playback experiments on 22 males of E. trivittatus. Male phonotactic reaction towards synthetic calls of various frequency values was evaluated as a binary variable (the male either approached or not the loudspeaker), by measuring the latency until first jump, and by calculating the linear approaching speed. As in E. femoralis, the maximum probability of positive reaction was matched to the call frequency. Against our expectations, the response curve was symmetric. We discuss whether these results reflect a lack of selective pressures, or a compromise between natural selection and physiological constraints on the shape of the frequency recognition curves.
Individual Odour Similarity and Discrimination in the Coruro (Spalacopus cyanus, Octodontidae)
Authors: Hagemeyer Petra , Begall Sabine
Published: March 2006

Previous studies of subterranean, fossorial and above‐ground rodents have demonstrated that similarities in individual odours covary with genetic similarities thus supporting the theory of odour‐genes covariance (i.e. the closer the individuals are genetically, the greater the similarities between their odours). We used the habituation‐generalization paradigm, where the subject is exposed to the same odour stimulus in three consecutive habituation trials followed by two test trials in which the odour from two other individuals are presented successively. Using this test design, we showed that the socially living coruros (Spalacopus cyanus) discriminate individuals on the basis of their ano‐genital odours and also respond to odour similarities between individuals. Male and female subjects treated ano‐genital odours of two same‐sex family members and also the odours of two sibling strangers as different to each other. At the same time, they treated the odours of siblings as similar compared with the odour of an unrelated individual. No gender differences were detected. Our results contrast with those from other rodent species that did not spontaneously discriminate between individual odours of siblings from a different family than their own. The polygyneous lifestyle may provide the selective background for that difference. Additional research will be necessary to explore this hypothesis and to rule out differences due to dietary preferences and due to the type of paradigm chosen for the tests.
Pedicularis and Castilleja are natural hosts of Cronartium ribicola in North America: a first report
Authors: McDonald G. I. , Richardson B. A. , Zambino P. J. , Klopfenstein N. B. , Kim M.‐S.
Published: March 2006

White pine blister rust disease, caused by the introduced pathogen Cronartium ribicola, has severely disrupted five‐needled pine ecosystems in North America. A 100‐year effort to manage this disease was predicated in part on the premise that the pathogen utilizes only species of Ribes (Grossulariaceae) as alternate hosts on this continent. The current study presents the first conclusive demonstration that some species in the family Orobanchaceae (Pedicularis racemosa and Castilleja miniata) are functioning as alternate hosts in a natural ecosystem of North America. This finding has implications for improving our understanding of epidemiology, pathogen adaptation and host–pathogen interactions within white pine blister rust.
Studies on anastomosis groups of Rhizoctonia solani isolates causing disease in two forest nurseries in Poland
Authors: StĘpniewska‐Jarosz S. , Mańka M. , Asiegbu F. O.
Published: March 2006

Thirty‐eight isolates of Rhizoctonia spp. were isolated from Scots pine (Pinus sylvestris) seedlings with damping‐off symptoms, originating from two forest nurseries in central‐west Poland (Wronczyn and Jarocin) and from diseased seedlings grown in soil from Wronczyn nursery. Majority of these isolates (79%) had multinucleate cells and were identified as Rhizoctonia solani. The remaining isolates were recognized as binucleate Rhizoctonia spp. R. solani isolates were characterized using hyphal anastomosis and were divided into five anastomosis groups (AG). The most prevalent was AG5 (37% of isolates), followed by AG2‐1 (30%) and 27% of the isolates were identified as AG4. Groups AG1‐IB and AG2‐2 were only represented by single isolates. The virulence recorded as mortality (in percentage) was comparatively high for binucleate and multinucleate isolates of Rhizoctonia spp. Sequence analysis of the polymerase chain reaction (PCR)‐amplified internal transcribed spacer (ITS) rDNA region was used for phylogenetic analysis. The dendrogram showed that isolates were distinctly separated based on their AG types and there was no relationship between pathogenicity on Scots pine seedlings and the AG to which the isolates belong to. The results are discussed with respect to pathogenic potential of the various AG groups.
EFFECTS OF EXERCISE‐INDUCED ARTERIAL HYPOXAEMIA ON LIMB MUSCLE FATIGUE AND PERFORMANCE
Authors: Romer Lee M , Dempsey Jerome A
Published: March 2006

Reductions in arterial O2 saturation (−5% to −10%Sao2 below rest) occur over time during sustained heavy‐intensity exercise in a normoxic environment, caused primarily by the effects of acid pH and increased temperature on the position of the HbO2 dissociation curve.

We prevented the desaturation incurred during exercise at ∼90% O2 MAX via increased fraction of inspired O2 (Fio2) (0.23 to 0.29) and showed that exercise time to exhaustion was increased.

We used supramaximal magnetic stimulation (1–100 Hz) of the femoral nerve to test for quadriceps fatigue. We used mildly hyperoxic inspirates (Fio2 0.23 to 0.29) to prevent O2 desaturation. We then compared the amount of quadriceps fatigue incurred following cycling exercise at Sao2 91% vs 98% with each trial carried out at identical work rates and for equal durations.

Preventing the normal exercise‐induced O2 desaturation prevented about one‐half the amount of exercise‐induced quadriceps fatigue; plasma lactate and effort perception were also reduced. In a subset of less fit subjects who showed only minimal arterial hypoxaemia during sustained exercise (Sao2∼95%), breathing a mildly hypoxic inspirate (Fio2 0.17; Sao2∼88%) exacerbated the quadriceps fatigue.

We conclude that the normal exercise‐induced O2 desaturation during heavy‐intensity endurance exercise contributes significantly to exercise performance limitation in part because of its effect on locomotor muscle fatigue.
PATIENT AGE IS A STRONG INDEPENDENT PREDICTOR OF 13C‐AMINOPYRINE BREATH TEST RESULTS: A COMPARATIVE STUDY WITH HISTOLOGY, DUPLEX‐DOPPLER AND A LABORATORY INDEX IN PATIENTS WITH CHRONIC HEPATITIS C VIRUS INFECTION
Authors: Schneider Arne RJ , Teuber Gerlinde , Paul Katrin , Nikodem Alice , Duesterhoeft Matthias , Caspary Wolfgang F , Stein Juergen
Published: March 2006

Noninvasive tests for the staging of chronic hepatitis C virus (HCV) infection would be an attractive alternative to liver biopsy. The 13C‐aminopyrine breath test (ABT) has been proposed for the noninvasive assessment of hepatic function and partly correlates with fibrosis. We aimed to investigate causes for the lack of discriminatory power for different degrees of hepatic fibrosis.

Eighty‐three patients (median age 49 years (28–78 years)) with chronic HCV infection underwent the ABT after an oral load of 75 mg N,N‐dimethyl‐13C‐aminopyrine. Portal vein flow was assessed by duplex‐Doppler and a laboratory index (aspartate aminotransferase to platelet ratio index or APRI) was calculated. Parameters were compared with liver histology.

The cumulative 13C‐recovery differed significantly between patients without relevant fibrosis (fibrosis score 0–2) and cirrhosis (5–6), beginning after 30 min of sampling (P < 0.05). The ABT did not discriminate patients with fibrosis scores 3–4 from the remaining two patient groups. Sensitivity and specificity for the prediction of cirrhosis was 73.4–82.8% and 63.2–68.4%, depending on the sampling time. Compared with the fibrosis score (P = 0.04), patient age was a highly significant independent predictor for the 13C‐recovery (P < 0.0001). Aspartate aminotransferase to platelet ratio index and duplex‐Doppler predicted cirrhosis with 76.6%vs. 87.5% sensitivity and 63.2%vs. 68.4% specificity.

Our data suggest an age‐dependent decrease of cytochrome P450 activity which probably accounts for the large overlap of ABT results that preclude clear differentiation. This is also consistent with former pharmacodynamic trials. Age‐adapted reference ranges could improve ABT results.
DIRECT EFFECTS OF QUERCETIN ON IMPAIRED REACTIVITY OF SPONTANEOUSLY HYPERTENSIVE RAT AORTAE: COMPARATIVE STUDY WITH ASCORBIC ACID
Authors: Ajay Machha , Achike Francis I , Mustafa Ali Mohd , Mustafa Mohd Rais
Published: March 2006

There is a growing interest in the anti‐oxidant characteristics and use of flavonoids in the management of cardiovascular diseases. The cardiovascular mechanism of action of these plant derivatives remains controversial. This study compared the effects of the flavonoid quercetin with those of the anti‐oxidant vitamin ascorbic acid (vitamin C) on the reactivity of aortic rings from spontaneously hypertensive rats (SHR).

The phenylephrine (PE)‐induced contractile and the endothelium‐dependent and independent relaxant responses of aortic rings from 21 to 22 week old SHR and age‐matched normotensive Wistar (WKY) rats were observed in the presence of quercetin or ascorbic acid. All the experiments were performed in the presence of the cyclooxygenase inhibitor, indomethacin (10 mmol/L).

The endothelium‐dependent and independent relaxations to acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, were significantly lesser in the SHR compared to the WKY tissues whereas the contractile responses to PE were similar in both tissues. Pretreatment of WKY rings with quercetin or ascorbic acid had no effect on the responses to ACh or PE. In the SHR tissues, however, quercetin or ascorbic acid significantly improved the relaxation responses to ACh and reduced the contractions to PE with greater potency for quercetin. Both compounds lacked any effects on the responses to SNP in either aortic ring types. Nw‐nitro‐L‐arginine methyl ester (l‐NAME, 10 mmol/L) significantly attenuated the vasodepressor effects of quercetin and ascorbic acid, raising the responses to PE to a level similar to that observed in the control SHR tissues. In l‐NAME pretreated aortic rings, quercetin and ascorbic acid inhibited the contractile responses to PE with the same magnitude in WKY and SHR tissues.

The present results suggest that acute exposure to quercetin improves endothelium‐dependent relaxation and reduces the contractile responses of hypertensive aortae with a greater potency than ascorbic acid. This suggests a better vascular protection with this flavonoid than ascorbic acid in the SHR model of hypertension and possibly in human cardiovascular diseases.
THERAPEUTIC EFFECT OF GREEN TEA EXTRACT ON ADVANCED GLYCATION AND CROSS‐LINKING OF COLLAGEN IN THE AORTA OF STREPTOZOTOCIN DIABETIC RATS
Authors: Babu Pon Velayutham Anandh , Sabitha Kuruvimalai Ekambaram , Shyamaladevi Chennam Srinivasulu
Published: March 2006

The therapeutic effect of green tea extract (GTE) on the aortic collagen content and its characteristics were investigated in streptozotocin diabetic rats.

Diabetes was induced in rats by a single intra peritoneal injection of streptozotocin (60 mg/kg bodyweight). Six weeks after diabetes induction, GTE was administered orally for four weeks (300 mg/kg bodyweight daily). Systolic blood pressure, blood glucose, anti‐oxidant status, collagen content, extent of glycation, collagen linked fluorescence and aortic collagen solubility pattern were determined in experimental rats.

At the end of the experimental period, there was a significant increase in the systolic blood pressure and blood glucose in diabetic rats. The lipid peroxides increased whereas glutathione and vitamin C levels were decreased in the serum of diabetic rats. The collagen content, extent of glycation, the advanced glycation end products (AGEs) and degree of cross‐linking were increased in the aorta of diabetic rats.

The oral administration of GTE to diabetic rats significantly reduced the systolic blood pressure and blood glucose. The level of lipid peroxides reduced and the content of glutathione and vitamin C increased in the serum of GTE treated diabetic rats. Green tea extract also impede the accumulation of aortic collagen, extent of glycation, formation of AGEs and cross‐linking of collagen in diabetic rats. The antihyperglycemic, anti‐oxidant and antiglycating effects of GTE ascribed for these beneficial effects. In conclusion, green tea may have therapeutic effect in the treatment of cardiovascular complications characterized by increased AGE accumulation and protein cross‐linking associated with diabetes.
ATORVASTATIN PREVENTED AND PARTIALLY REVERSED ADRENOCORTICOTROPIC HORMONE‐INDUCED HYPERTENSION IN THE RAT
Authors: Mondo Charles K , Yang Wan‐Song , Su Ji‐Zhou , Huang Ti‐Gang
Published: March 2006

Adrenocorticotropic hormone (ACTH)‐induced hypertension is associated with nitric oxide (NO) deficiency and increased oxidative stress. Atorvastatin (Ato), an HMG‐Co‐enzyme‐A reductase inhibitor has been reported to enhance availability of NO. The aim of the study was to assess whether pretreatment with Ato would prevent the development of ACTH‐induced hypertension and whether established ACTH‐induced hypertension could be reversed with subsequent administration of Ato in rats.

Male Sprague‐Dawley rats (n = 60) were treated with Ato (30 mg/kg per day in drinking water) or tap water for 15 days. ACTH (0.2 mg/kg per day s.c) or saline was started 4 days after Ato treatment or non‐treated rats and continued for 11–13 days (prevention study). In the reversal study, Ato was given on day 8 of ACTH/Saline treatment for 5 days. Systolic blood pressure (SBP) was measured on alternate days using the tail cuff method.

Adrenocorticotropic hormone treatment increased SBP (110 ± 2–136 ± 2 mmHg, P < 0.001) and aortic superoxide production (P < 0.001). Ato alone did not alter SBP, but Ato pretreatment prevented ACTH‐induced hypertension compared with that in rats treated with ACTH alone (118 ± 2 and 136 ± 2 mmHg, respectively, P¢ < 0.01). Ato partially reversed ACTH‐induced hypertension (124 ± 3 and 136 ± 2 mmHg, respectively, P¢ < 0.05). Plasma nitrate/nitrite (NOx) was decreased in ACTH‐treated rats compared with saline treated rats (6.6 ± 0.4 saline and 4.5 ± 0.5 mmol/L ACTH, P < 0.001). Atorvastatin affected neither plasma NOx nor aortic superoxide production.

Atorvastatin prevented and partially reversed ACTH‐induced hypertension in the rat.
UPREGULATION OF 14‐3‐3 ISOFORMS IN ACUTE RAT MYOCARDIAL INJURIES INDUCED BY BURN AND LIPOPOLYSACCHARIDE
Authors: He Ming , Zhang Jixiang , Shao Lijian , Huang Qiren , Chen Jie , Chen Heping , Chen Xuanying , Liu Dan , Luo Zhijun
Published: March 2006

Burn‐induced myocardial injuries can be acute due to loss of body fluid and blood redistribution, and subacute due to pathogenic toxins of infecting bacteria. The goal of this study was to examine expression of 14‐3‐3 in the injured myocardium.

Myocardial injury models were created in vivo by subjecting rats to severe burn and administration of lipopolysaccharide. RT‐PCR and Western blotting were employed to assess the expression of 14‐3‐3 proteins and messenger ribonucleic acid (mRNA) for 14‐3‐3h and g in the myocardium, respectively.

In the two models, we found that 14‐3‐3 proteins were induced in a time‐dependent fashion. Such a change is at least in part attributed to increases in mRNAs for 14‐3‐3g and h. In contrast to 14‐3‐3z, whose mRNA was not detectable in the heart, mRNA for 14‐3‐3g was found significantly elevated between 24–48 h after burn. 14‐3‐3h mRNA exhibited a marked increase at 3 h continuing to 12 h and then decreased nearly to a normal level after 48 h. In lipopolysaccharide‐treated intact rats, 14‐3‐3g mRNA in myocardium showed a significant increase, reaching a peak at 4 h, followed by a decrease at 6 h. In contrast, 14‐3‐3h mRNA had a slight increase without significance.

Our results suggest that 14‐3‐3 may play a role in both acute and subacute (postburn infectious) phases of severe burn.
FLUVASTATIN INCREASES HETEROTOPICALLY INDUCED OSSICLES IN MICE
Authors: Galus R , Wlodarski PK , Wlodarski KH
Published: March 2006

The aim of the present study was to evaluate the influence of fluvastatin (3‐hydroxy‐3‐methylglutarylcoenzyme A reductase inhibitor) on heterotopic ossification (HO) induced by HeLa cells.

C57Bl/6 mice were injected with 3 ¥ 106 HeLa cells into right thigh muscles. Mice in the experimental group received fluvastatin 1.2 mg/kg per day for 17 consecutive days, while mice in the control group received placebo. Intact mice served as an additional control. Seventeen days post‐HeLa cell grafting, blood samples were collected to measure total serum cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol and alkaline phosphatase (AP).

In all animals injected with HeLa cells, the mass of mineral deposited in the induced ossicle was established after hydrolysis of soft tissues surrounding the induced ossicles. In fluvastatin‐treated mice, the mass of mineral deposited in heterotopically induced ossicles was significantly increased, when compared to mice receiving placebo. This was followed by a significant decrease of TG concentration; whereas the levels of serum AP were not significantly affected.

These results indicate that administration of statins may affect heterotopic ossification. This may also have clinical implication, because patients predisposed to HO and receiving statins during hypocholesterolemic treatment, may be at even greater risk of HO.
Dyspeptic symptoms associated with hypersensitivity to gastric distension induced by duodenal acidification
Authors: LEE KWANG JAE , KIM JIN HONG , CHO SUNG WON
Published: March 2006

Background and Aim:  Duodenal acidification might increase sensitivity to gastric distension, which seems to play a role in the genesis of dyspeptic symptoms in a subset of patients with functional dyspepsia. The aim of the present study was to investigate the characteristics of dyspeptic symptoms associated with hypersensitivity to gastric distension induced by duodenal acidification.

Methods:  An infusion tube and a barostat bag were positioned in the duodenum and gastric fundus, respectively. Sensitivity to stepwise fundic distensions with severity scoring of the seven dyspeptic symptoms was assessed before and during duodenal acid infusion in 20 healthy subjects.

Results:  Acid infusion significantly decreased the pressures and the corresponding wall tensions at the thresholds for discomfort. At the distending level of minimal distending pressure (MDP) + 2 mmHg, significantly higher scores of fullness and bloating were obtained during acid infusion. With distending stimuli of MDP + 4 and 6 mmHg, fullness, bloating, nausea, satiety, epigastric burning and epigastric pain were significantly more severe during acid infusion than before acid infusion. At the level of MDP + 8 mmHg, the severity of epigastric pain was significantly greater, compared with that before acid infusion.

Conclusions:  Duodenal acidification might aggravate dyspeptic symptoms through the induction of hypersensitivity to gastric distension in healthy individuals. Those symptoms are diverse and variable, depending on the strength of the distending stimuli.
Enteroliths developed in a chronically obstructed afferent loop coexisting with gastric remnant carcinoma: Case report and review of the literature
Authors: Yavuz Nihat , Ergüney Sabri , Ögüt Gunduz , Alver Olcay
Published: March 2006

A case of gastric remnant carcinoma coexisting with a chronic afferent loop syndrome harboring multiple enteroliths in a grossly dilated and elongated afferent loop is presented herein. The patient had undergone a Polya type antecolic Billroth II reconstruction for a stenosing duodenal ulcer 40 years previously. A concise review of the relevant literature is also presented.
Pregnancy complicated by multiple pituitary hormone deficiencies
Authors: Fukami Tatsuya , Makino Yasuo , Kawarabayashi Tatsuhiko
Published: March 2006

We report a case of pituitary dwarfism and diabetes insipidus due to pituitary stalk transection in a pregnant Japanese woman, 138 cm in height, born by breech delivery with no evidence of ante‐ or intrapartum asphyxia. The patient had no central nervous disturbance, was diagnosed with pituitary dwarfism during childhood and was treated at another hospital with growth hormone supplement from 5 to 14 years of age. This patient was referred to our department at 17 weeks’ gestation due to a change of residence. At 30 weeks’ gestation, she was hospitalized for assessment of hydronephrosis and polyuria (15–20 L/day). Analysis of a 24‐h urine sample showed creatinine clearance of 157 mL/min and urine osmolality of 38 mOsm/L. The patient's urine output decreased after receiving a test dose of 0.75 g of 1‐desamino‐8‐D‐arginine vasopressin (DDAVP). Cranial magnetic resonance imaging showed transection of the pituitary stalk. Subsequently, the patient's urine output was well controlled by a maintenance dose of 0.275 mL/day intranasal DDAVP. A cesarean section was performed at 37 weeks, as the patient height was 138 cm, and a pelvic X‐ray showed cephalopelvic disproportion. She delivered a female baby weighing 2302 g, and both 1‐ and 5‐min Apgar scores were 9. The patient was followed up after 4 months and showed no visual deterioration or polyuria while on DDAVP therapy, while the neonate grew favorably.
Axonal damage and demyelination in long‐term dorsal root ganglia cultures from a rat model of Charcot–Marie–Tooth type 1A disease
Authors: Nobbio Lucilla , Gherardi Gianfranco , Vigo Tiziana , Passalacqua Mario , Melloni Edon , Abbruzzese Michele , Mancardi Gianluigi , Nave Klaus‐Armin , Schenone Angelo
Published: March 2006

Clinical progression in hereditary and acquired demyelinating disorders of both the central and peripheral nervous system is mainly due to a time‐dependent axonal impairment. We established 90‐day dorsal root ganglia (DRG) cultures from a rat model of Charcot–Marie–Tooth type 1A (CMT1A) neuropathy to evaluate the structure of myelin and axons, and the expression of myelin‐related proteins and cytoskeletal components, by morphological and molecular techniques. Both wild‐type and CMT1A cultures were rich in myelinated fibres. Affected cultures showed dysmyelinated internodes and focal myelin swellings. Furthermore, uncompacted myelin and smaller axons with increased neurofilament (NF) density were found by electron microscopy, and Western blots showed higher levels of nonphosphorylated NF. Confocal microscopy demonstrated an abnormal distribution of the myelin‐associated glycoprotein which, instead of being expressed at the noncompact myelin level, showed focal accumulation along the internodes while other myelin proteins were normally distributed. These findings suggest that CMT1A DRG cultures, similarly to the animal model and human disease, undergo axonal atrophy over a period of time. This model may be utilized to study the molecular changes underlying demyelination and secondary axonal impairment. As axonal damage may occur after just 3 months and tissue cultures represent a strictly controlled environment, this model may be ideal for testing neuroprotective therapies.
Kv3 potassium channels control the duration of different arousal states by distinct stochastic and clock‐like mechanisms
Authors: Joho Rolf H. , Marks Gerald A. , Espinosa Felipe
Published: March 2006

Sleep–wake behavior is tightly controlled in many animal species, suggesting genetically encoded, homeostatic control mechanisms that determine arousal‐state dynamics. We reported that two voltage‐gated potassium channels, Kv3.1 and Kv3.3, control sleep in wild‐type and Kv3‐mutant mice. Compared with wild‐type (WT), homozygous double mutants (DKO) that lack these channels sleep 40% less in the light and 22% less in the dark. To understand how the lack of these channels affects sleep, we analysed arousal‐state changes during the light period where the differences are greatest between WT and DKO. We determined the kinetic complexity of each arousal state from the episode durations of wakefulness, slow‐wave sleep and rapid eye movement sleep (REMS). Based on the number of exponential components in episode‐duration histograms, WT and DKO mice have several kinetically distinct states of wakefulness, and these states are longer in duration in DKO. For slow‐wave sleep, WT mice have a single slow‐wave sleep (SWS) state in contrast to DKO mice, which show two distinct SWS states, one that is 60% shorter than that in WT and a second that is similar in duration. Both WT and DKO mice have two kinetically distinct REMS states. DKO mice show an 84% reduction in the frequency of short REMS episodes (< 45 s) without any change in the occurrence of long REMS episodes (> 60 s). In contrast to the stochastic control of episode durations of wakefulness and SWS, the durations of both REMS states are normally distributed, indicating that the underlying control processes are fundamentally different.
Estrogen‐dependent selectivity of genomic responses to birdsong
Authors: Maney Donna L. , Cho Ellen , Goode Christopher T.
Published: March 2006

Behavioral responses to sociosexual signals often depend on gonadal steroid hormones, which are thought to modulate behavior by acting on motivational systems in the brain. There is mounting evidence that sex steroids may also modulate perception of sociosexual signals by affecting sensory processing. In seasonally breeding songbirds such as the white‐throated sparrow (Zonotrichia albicollis), the female's behavioral response to hearing male song depends on her plasma levels of estradiol (E2). Here, we examined whether plasma E2 also affects the selectivity of the song‐induced zenk (egr‐1) response in the auditory forebrain, which is known to vary according to the behavioral relevance of song stimuli. Non‐breeding females were held on a winter‐like photoperiod and implanted with silastic capsules containing either no hormone or E2. E2‐treated birds hearing 42 min of conspecific song had more cells immunoreactive for the protein product of zenk in the auditory forebrain than did those hearing frequency‐matched synthetic tones. In birds not treated with E2, however, the zenk response to song did not differ from that to tones. We found similar effects in the avian homolog of the inferior colliculus, indicating that E2 may affect the processing of auditory information upstream of the forebrain. Our data suggest that in females, zenk induction in the auditory system is selective for song only when plasma E2 exceeds non‐breeding levels. E2‐dependent plasticity of auditory pathways and processing centres may promote recognition of and attention to conspecific song during the breeding season.
Olfactory sensory neurons expressing class I odorant receptors converge their axons on an antero‐dorsal domain of the olfactory bulb in the mouse
Authors: Tsuboi Akio , Miyazaki Takaaki , Imai Takeshi , Sakano Hitoshi
Published: March 2006

Vertebrate odorant receptor (OR) genes are divided phylogenetically into two distinct classes: the fish‐like class I and the terrestrial‐specific class II. In the present study, we systematically analysed mouse class I OR genes (42 subfamilies) to elucidate the expression profiles in the olfactory epithelium (OE) and the projection sites of their olfactory sensory neurons (OSNs) in the olfactory bulb (OB). In situ hybridization (ISH) revealed that most class I OR genes (36 subfamilies) were expressed in the dorso‐medial zone (zone 1) of the OE. Furthermore, there appeared to be no significant differences in the distributions of OSNs expressing class I genes within zone 1. These results indicate that there is a clear boundary between zone 1 and non‐zone 1 areas in the OE. Some class I ORs are known to possess ligand specificity for aliphatic acids, aldehydes and alcohols. Our ISH analysis has revealed that OSNs expressing the class I ORs in zone 1 tend to converge their axons on a cluster of glomeruli in an antero‐dorsal domain that is assumed to be involved in responses to the aliphatic compounds on the OB.
Dopaminergic modulation of long‐lasting direct current‐induced cortical excitability changes in the human motor cortex
Authors: Nitsche Michael A. , Lampe Christian , Antal Andrea , Liebetanz David , Lang Nicolas , Tergau Frithjof , Paulus Walter
Published: March 2006

Dopaminergic mechanisms participate in N‐methyl‐d‐aspartate (NMDA) receptor‐dependent neuroplasticity, as animal experiments have shown. This may be similar in humans, where dopamine influences learning and memory. We tested the role of dopamine in human cortical neuroplasticity. Changes of excitability were induced by transcranial direct current stimulation (tDCS). D2 receptor blocking by sulpiride abolished the induction of after‐effects nearly completely. D1 activation alone in the presence of D2 receptor blocking induced by co‐administration of sulpiride and pergolide did not re‐establish the excitability changes induced by tDCS. This suggests that D2 receptors play a major supporting role in inducing neuroplasticity in the human motor cortex. Enhancement of D2 and, to a lesser degree, D1 receptors by pergolide consolidated tDCS‐generated excitability diminution until the morning after stimulation. The readiest explanation for this pattern of results is that D2 receptor activation has a consolidation‐enhancing effect on tDCS‐induced changes of excitability in the human cortex. The results of this study underscore the importance of the dopaminergic system for human neuroplasticity, suggest a first pharmacological add‐on mechanism to prolong the excitability‐diminishing effects of cathodal tDCS for up to 24 h after stimulation, and thus render the application of tDCS practicable in diseases displaying enhanced cortical excitability, e.g. migraine and epilepsy.
Force and time control in the production of rhythmic movement sequences in Parkinson's disease
Authors: Pope Paul A. , Praamstra Peter , Wing Alan M.
Published: March 2006

This study investigated force and time control in rhythm production in Parkinson's disease. Patients and age‐matched controls reproduced rhythms consisting of equal (600 ms) or alternating (400 and 800 ms) intervals, produced with equal (12 N) or alternating (8 and 16 N) forces, under paced (synchronization) and unpaced (continuation) conditions. Performance was assessed in terms of accuracy and variability. Reproduction of force amplitudes was less accurate in patients than in controls when either time or force alternated but did not deteriorate further when force and time alternated. In contrast, interval timing was least accurate in patients compared with controls when rhythm alternated on both dimensions. The ratio between alternating force levels was better maintained by controls than by patients, without influence of timing requirements in either group. In contrast, the ratio between alternating intervals was relatively preserved in patients when force remained constant but was severely compromised when force alternated. Timing variability was greater in the patient group, especially in the more affected side, but there was no difference in timing variability between groups as a function of rhythm, and there were no differences between groups in variability of force. The results show that force and time control in patients are affected in different ways. We interpret the preserved timing of rhythms with alternation on one dimension as evidence of intact ability to organize movements in a sequence. The data are compatible with a basal ganglia role in the coregulation of time and force, but do not support a general timing function of the basal ganglia.
CB2 receptor‐mediated antihyperalgesia: possible direct involvement of neural mechanisms
Authors: Beltramo M. , Bernardini N. , Bertorelli R. , Campanella M. , Nicolussi E. , Fredduzzi S. , Reggiani A.
Published: March 2006

In mouse the cannabinoid receptor 2 (CB2) agonists L768242 and (+)‐AM1241, at doses of 30 mg/kg i.p. and 1 and 3 mg/kg i.v., respectively, reduced the second phase of nocifensive behaviors elicited by formalin intraplantar injection. This effect was counteracted by the selective CB2 antagonist SR144528 (1 mg/kg i.p.). In rat (+)‐AM1241 (3 and 6 mg/kg i.v.) and L768242 (30 mg/kg i.p.) reduced allodynia elicited by L5–L6 spinal nerve ligation. SR144528 reverted these effects, supporting a CB2‐mediated action. To clarify the mechanisms underlying these effects we investigated CB2 gene expression and function in the nervous system. CB2 mRNA was expressed in spinal cord and dorsal root ganglia (DRG) of both sham and neuropathic rats and was up‐regulated in the ipsilateral spinal cord of neuropathic rats. Expression studies demonstrated the presence of CB2 mRNA in culture of spinal cord microglia. A biomarker, CGRP, was used to investigate modulation of DRG primary afferents by CB2 agonists. Both L768242 and (+)‐AM1241 dose dependently (EC50 of 3.6 and 4.5 nm, respectively) reduced capsaicin‐induced calcitonin gene‐related peptide (CGRP) release. Coadministration of SR144528 resulted in a rightforward shift (pKB 8.1 and 8.2 for (+)‐AM1241 and L768242, respectively) of the dose–response curve. Experiments on capsaicin‐induced CGRP release in tissue from CB1–/– mice ruled out a CB1‐mediated effect. These results confirm that CB2 is present in the central nervous system and suggest that CB2 agonists may elicit their analgesic effect by acting not only at non‐neuronal peripheral sites but also at neural level, making CB2 an attractive target for chronic pain treatment.
Identification of genes co‐upregulated with Arc during BDNF‐induced long‐term potentiation in adult rat dentate gyrus in vivo
Authors: Wibrand Karin , Messaoudi Elhoucine , Håvik Bjarte , Steenslid Vibeke , Løvlie Roger , Steen Vidar M. , Bramham Clive R.
Published: March 2006

Brain‐derived neurotrophic factor (BDNF) is a critical regulator of transcription‐dependent adaptive neuronal responses, such as long‐term potentiation (LTP). Brief infusion of BDNF into the dentate gyrus of adult anesthetized rats triggers stable LTP at medial perforant path‐granule synapses that is transcription‐dependent and requires induction of the immediate early gene Arc. Rather than acting alone, Arc is likely to be part of a larger BDNF‐induced transcriptional program. Here, we used cDNA microarray expression profiling to search for genes co‐upregulated with Arc 3 h after BDNF‐LTP induction. Of nine cDNAs encoding for known genes and up‐regulated more than four‐fold, we selected five genes, Narp, neuritin, ADP‐ribosylation factor‐like protein‐4 (ARL4L), TGF‐β‐induced immediate early gene‐1 (TIEG1) and CARP, for further validation. Real‐time PCR confirmed robust up‐regulation of these genes in an independent set of BDNF‐LTP experiments, whereas infusion of the control protein cytochrome C had no effect. In situ hybridization histochemistry further revealed up‐regulation of all five genes in somata of post‐synaptic granule cells following both BDNF‐LTP and high‐frequency stimulation‐induced LTP. While Arc synthesis is critical for local actin polymerization and stable LTP formation, several of the co‐upregulated genes have known functions in excitatory synaptogenesis, axon guidance and glutamate receptor clustering. These results provide novel insight into gene expression responses underlying BDNF‐induced synaptic consolidation in the adult brain in vivo.
Effect of auditory cortex lesions on the discrimination of frequency‐modulated tones in rats
Authors: Rybalko Natalia , Šuta Daniel , Nwabueze‐Ogbo Fidel , Syka Josef
Published: March 2006

The lateralization of functions to individual hemispheres of the mammalian brain remains, with the exception of the human brain, unresolved. The aim of this work was to investigate the ability to discriminate between falling and rising frequency‐modulated (FM) stimuli in rats with unilateral or bilateral lesions of the auditory cortex (AC). Using an avoidance conditioning procedure, thirsty rats were trained to drink in the presence of a rising FM tone and to stop drinking when a falling FM tone was presented. Rats with a lesion of the AC were able to learn to discriminate between rising and falling FM tones; however, they performed significantly worse than did control rats. A greater deficit in the ability to discriminate the direction of frequency modulation was observed in rats with a right or bilateral AC lesion. The discrimination performance (DP) in these rats was significantly worse than the DP in rats with a left AC lesion. Animals with a right or bilateral AC lesion improved their DP mainly by recognizing the pitch at the beginning of the stimuli. The lesioning of the AC in trained animals caused a significant decrease in DP, down to chance levels. Retraining resulted in a significant increase in DP in rats with a left AC lesion; animals with a right lesion improved only slightly. The results demonstrate a hemispheric asymmetry of the rat AC in the recognition of FM stimuli and indicate the dominance of the right AC in the discrimination of the direction of frequency modulation.
Patterns in body mass distributions: sifting among alternative hypotheses
Authors: Allen C. R. , Garmestani A. S. , Havlicek T. D. , Marquet P. A. , Peterson G. D. , Restrepo C. , Stow C. A. , Weeks B. E.
Published: March 2006

Understanding how animals interact with their environment is critical for evaluating, mitigating and coping with anthropogenic alteration of Earth's biosphere. Researchers have attempted to understand some aspects of these interactions by examining patterns in animal body mass distributions. Energetic, phylogenetic, biogeographical, textural discontinuity and community interaction hypotheses have been advanced to explain observed patterns. Energetic and textural discontinuity hypotheses focus upon the allometry of resource use. The community interaction hypothesis contends that biotic interactions within assemblages of species are of primary importance. Biogeographical and phylogenetic hypotheses focus on the role of constraints on the organization of communities. This paper examines and organizes these various propositions about species body mass distributions and discusses the multiple competing hypotheses, how their predictions vary, and possible methods by which the hypotheses can be distinguished and tested. Each of the hypotheses is partial, and explains some elements of pattern in body mass distributions. The scale of appropriate application, relevance and interpretation varies among the hypotheses, and the mechanisms underlying observed patterns are likely to be multicausal and vary with scale.
Expression profiles of fhs (FTHFS) genes support the hypothesis that spirochaetes dominate reductive acetogenesis in the hindgut of lower termites
Authors: Pester Michael , Brune Andreas
Published: March 2006

Reductive acetogenesis is an important metabolic process in the hindgut of wood‐feeding termites. We analysed diversity and expression profiles of the bacterial fhs gene, a marker gene encoding a key enzyme of reductive acetogenesis, formyl tetrahydrofolate synthetase (FTHFS), to identify the active homoacetogenic populations in representatives of three different termite families. Clone libraries of polymerase chain reaction‐amplified fhs genes from hindgut contents of Reticulitermes santonensis (Rhinotermitidae) and Cryptotermes secundus (Kalotermitidae) were compared with previously published fhs gene sequences obtained from Zootermopsis nevadensis (Termopsidae). Most of the clones clustered among the ‘Termite Treponemes’, which comprise also the fhs genes of the two strains of the homoacetogenic spirochaete Treponema primitia. The high abundance of treponemal fhs genes in all clone libraries was in agreement with the results of DNA‐based terminal‐restriction fragment length polymorphism (T‐RFLP) analysis. Moreover, in mRNA‐based T‐RFLP profiles of the three termites, only expression of fhs genes of ‘Termite Treponemes’ was detected, albeit at different levels. In C. secundus, only one of the dominating phylotypes was transcribed, while in R. santonensis, the apparently less abundant fhs genes were the most actively expressed. Our results strongly support the hypothesis that spirochaetes are responsible for reductive acetogenesis in the hindgut of lower, wood‐feeding termites.
A paradox explained? Patients with delayed diagnosis of symptomatic colorectal cancer have good prognosis
Authors: Rupassara K. S. , Ponnusamy S. , Withanage N. , Milewski P. J.
Published: March 2006

Objective  To investigate the impact on outcome of delay between referral and diagnosis in colorectal cancer (CRC).

Patients and methods  One hundred and fifty‐four patients were studied after excluding from a consecutive series of 411 with CRC, those with factors known to affect the prognosis that may also have affected the speed of diagnosis. These were advanced disease, emergency admission or surgery, referral with diagnosis already made, and tumours treated by colonoscopic polypectomy alone. Possible causative factors were compared between early and late diagnosis groups. For assessment of symptom risk, the Department of Health criteria were used.

Results  Forty‐four patients had Referral to Diagnosis Interval (RDI) ≥ 50 days (‘Late’), and 110 had RDI < 50 days (‘Early’). In the Late group there were only 2 deaths from cancer and 93.7% cancer‐specific five year survival (c5ys), compared with 22 and 65.3%, respectively, in the Early one (P = 0.007). There were more Duke's A cases in the Late group (38.6%vs 15.2%, P = 0.006), but this did not fully explain the improved survival. Comparisons for each Duke's Stage showed improved c5ys for Late Duke's B ones (100% of 16 vs 60.3% of 54, P = 0.039). Late patients had more low risk symptoms than Early ones, both overall (31.8%vs 13.7%, P = 0.013) and in Duke's B cases (56%vs 15.3%, P = 0.003). Tumours were smaller in the Late group (length 35.3 vs 41.6 mm, P= 0.04); this difference was confined to the Duke's A patients and sigmoid tumours. Late sigmoid tumours were not only shorter (32.4 vs 45.9 mm, P = 0.02) but also were all cured (c5ys 100% of 18 vs 60.3% of 23, P = 0.011). There were no differences between Late and Early groups in: age (mean 69.9 years), sex (male 57.7%), date of diagnosis (mean December 1998), ASA comorbidity index (mean 1.9), number of lymph nodes found in the operative specimen (mean 8.6), or histological grading (moderate differentiation 94.4%).

Conclusion  In the context of modern rapid access clinics, symptomatic CRC patients with delay between referral and diagnosis (even if this is several months or occasionally more than a year) have less aggressive tumours and markedly better long‐term cure rate than their earlier diagnosed counterparts. Attempts to speed up further the diagnosis would be a waste of time and resources, being unlikely to make an appreciable difference to the overall cure rate.
The ultrastructure of the spermatozoa of Boa constrictor occidentalis, with considerations on its mating system and sperm competition theories
Authors: Tourmente M. , Cardozo G. , Bertona M. , Guidobaldi A. , Giojalas L. , Chiaraviglio M.
Published: March 2006

Sperm ultrastructure has been described for several families of Squamata in which it has been considered a valuable character source for phylogenetic studies. However, sperm competition and mating systems have been demonstrated to influence variations in the sperm morphology and dynamics. The mating system of Boa constrictor occidentalis is likely to have a high degree of sperm competition. We investigated, for the first time, the ultrastructure of the spermatozoa of B. c. occidentalis and, thus, of the family Boidae. Active mating groups were captured from the field, and the spermatozoa of the males was collected by ejaculation and processed to obtain transmission electron micrographs and fluorescence micrographs. The spermatozoa are filiform and their morphology fits the general model described for snakes, and several synapomorphies belonging to the squamates can be identified in these cells. Nevertheless, the head is 25% longer and the midpiece presents a lower frequency of mitochondrial transformations than that of other snakes. We propose that this last trait, along with the extraordinary elongation of the midpiece and the system of multilaminar membranes covering this section (both synapomorphies of the snake spermatozoa), are adaptive responses to processes of sperm competition and sperm storage.
Cytological evaluation of the germ cell development strategy within the testis of the American alligator, Alligator mississippiensis
Authors: Gribbins Kevin M. , Elsey Ruth M. , Gist Daniel H.
Published: March 2006

The cytological changes to germ cells were investigated within the seminiferous epithelium of the American alligator (Alligator mississippiensis). Testicular tissues were collected, embedded in plastic, sectioned on an ultramicrotome, and stained with the periodic acid–Schiff+ procedure followed by a haematoxylin counterstain. Alligators have a prenuptial pattern of germ cell development, where spermatogenesis begins in early spring and sperm is mature by the time mating begins in May. Consistent spatial relationships between germ cells are absent within the seminiferous epithelium of the alligator. Their germ cells progress through the phases of spermatogenesis as a single cohort, leading to one continuous spermiation event that occurs during their mating season (May–June). This temporal germ cell development is different from the consistent spatial development seen within seasonally breeding birds and mammals but is similar to the recently described germ cell development strategies of two other temperate breeding reptiles, the slider turtle and the European wall lizard. The germ cell development strategy shared by these three temperate reptiles representing three different taxa within the class Reptilia is reminiscent of the temporal strategy seen within the anamniotic testis. Thus, alligators and at least two other temperate reptiles exhibit primitive spermatogenic cycles within derived amniotic testes and may be consider intermediates in terms of testicular organization, which may have significance phylogenetically.