Functionally homologous representation of vocalizations in the auditory cortex of humans and macaques

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Characterization of the Carbohydrate Chain on the Substance P Receptor in the Rat Brain Cortex: Effect of Lectins on [3H]Substance P Binding

The characteristics of the carbohydrate chain on the rat cerebral cortical substance P (SP) receptor were studied. We examined the effects of pretreatment with three lectins (concanavalin A, wheat germ agglutinin, lens culinaris agglutinin) on the [3H]SP binding activities. Each lectin can bind to the specific carbohydrate chain. Among these lectins, only concanavalin A inhibited specific [3H]SP binding by reducing the affinity of the binding sites. The inhibitory action of concanavalin A was dose-dependent and diminished by the addition of alpha-methyl-D-mannoside. The present results suggest that the rat cortical SP receptor has either a biantennary complex-type or a high mannose-type of carbohydrate chain, and that the carbohydrate chain is implicated in the SP binding activity of the SP receptor system.     

Determination of epidemiological relationships of Streptococcus agalactiae isolated from bovine mastitis

In the present study 79 streptococcal cultures isolated from subclinical mastitis of 54 cows from seven dairy farms (A-G) in Hesse, Germany, were comparatively investigated using conventional and molecular methods. The isolates could be identified as Streptococcus agalactiae, belonging to Lancefield's serological group B by determination of cultural, biochemical and serological properties and by polymerase chain reaction (PCR)-mediated amplification of species-specific parts of the 16S ribosomal DNA, the 16S-23S rDNA intergenic spacer region and the CAMP factor gene cfb. The investigated group B streptococci were further characterized serologically for specific polysaccharide and protein antigens. Serotyping the isolates revealed a predominance of surface protein antigen X, either alone or in combination with polysaccharide antigen Ia. This could be observed for 39 isolates of farms A, B and C. Six group B streptococci from farm E displayed the serotype pattern III/Rib, two isolates from farm G showed the serotype pattern Ib/calpha. The remaining cultures from farms D and F (n=32) were non-typable. The occurrence of protein Rib could be confirmed by PCR amplification of the gene rib. The two isolates with serotype pattern Ib/calpha also reacted positively for the cbeta-encoding gene bag. Additional properties which allowed a phenotypic characterization of the S. agalactiae were the degree of pigmentation, growth properties in fluid media and soft agar, the surface hydrophobicity, the ability to hemagglutinate rabbit erythrocytes and their resistance reactions to tetracycline and minocycline. The isolates of the seven farms showed identical or almost identical characteristics. The 79 group B streptococci were additionally investigated by macrorestriction analysis of their chromosomal DNA using the restriction endonucleases SmaI, ApaI and SalI. The restriction patterns obtained by pulsed-field gel electrophoresis displayed identical or closely related patterns for the cultures of the various farms. The pheno- and genotypic characteristics of the 79 group B streptococci of the present study revealed that a single S. agalactiae strain or at least closely related subtypes of this strain were responsible for the mastitis situation of the seven farms.     

Pancreatic polypeptides affect luteinizing and growth hormone secretion in rats

We have examined the effects of third cerebroventricular (3V) injections of avian and bovine pancreatic polypeptide (APP and BPP) and the C-terminal hexapeptide amide of human PP (CHPP) on the secretion of anterior pituitary hormones in conscious ovariectomized rats. Injection of APP (2.0 micrograms; 472 pmoles) or BPP (5.0 micrograms; 1191 pmoles) decreased plasma levels of luteinizing hormone (LH) when compared to pre-injection levels in these animals or to saline-injected controls. The lower dose of BPP (0.5 micrograms; 119 pmoles) decreased plasma LH versus pre-injection levels and control animals, however, these effects diminished at later times. Plasma growth hormone (GH) also decreased following 3V injections of APP (2.0 micrograms) or BPP (5.0 micrograms). The lower dose of BPP (0.5 microgram) initially inhibited GH release, however, this effect was rapidly reversed and GH levels were significantly greater than those in controls at 60 and 120 min. Injections of BPP or APP did not alter prolactin (PRL) or thyroid stimulating hormone (TSH) secretion. Administration of 2.0 micrograms and 0.2 microgram of CHPP (2488 and 249 pmoles) produced no significant effects on plasma LH, GH, PRL or TSH. APP and BPP had no consistent effects on hormone secretion from dispersed anterior pituitary cells. The results indicate that APP and BPP exert potent central effects which inhibit LH and GH release from the pituitary gland.     

Effects of Stimulation of the Periaqueductal Gray and <Emphasis Type="Italic">Locus Coeruleus</Emphasis> on Postsynaptic Reactions of Cat Somatosensory Cortex Neurons Activated by Nociceptors

In cats, we studied the influences of stimulation of the periaqueductal gray (PAG) and locus coeruleus (LC) on postsynaptic processes evoked in neurons of the somatosensory cortex by stimulation of nociceptive (intensive stimulation of the tooth pulp) and non-nociceptive (moderate stimulations of the infraorbital nerve and ventroposteromedial nucleus of the thalamus) afferent inputs. Twelve cells activated exclusively by nociceptors and 16 cells activated by both nociceptive and non-nociceptive influences (hereafter, nociceptive and convergent neurons, respectively) were recorded intracellularly. In neurons of both groups, responses to nociceptive stimulation (of sufficient intensity) looked like an EPSP-spike-IPSP (the latter, of significant duration, up to 200 msec) complex. Electrical stimulation of the PAG (which could itself evoke activation of the cortical neurons under study) resulted in long-term suppression of synaptic responses evoked by excitation of nociceptors (inhibition reached its maximum at a test interval of 600 to 800 msec). We observed a certain parallelism between conditioning influences of PAG activation and effects of systemic injections of morphine. Isolated stimulation of LC by a short high-frequency train of stimuli evoked primary excitatory responses (complex EPSPs) in a part of the examined cortical neurons, while in other cells high-amplitude and long-lasting IPSP (up to 120 msec) were observed. Independently of the type of the primary response to PAG stimulation, the latter resulted in long-term (several seconds) suppression of the responses evoked in cortical cells by stimulation of the nociceptive inputs. The mechanisms of modulatory influences coming from opioidergic and noradrenergic brain systems to somatosensory cortex neurons activated due to excitation of high-threshold (nociceptive) afferent inputs are discussed.Neirofiziologiya/Neurophysiology, Vol. 37, No. 1, pp. 61–73, January–February, 2005.     

Thinned-skull Cortical Window Technique for In Vivo Optical Coherence Tomography Imaging

Optical coherence tomography (OCT) is a biomedical imaging technique with high spatial-temporal resolution. With its minimally invasive approach OCT has been used extensively in ophthalmology, dermatology, and gastroenterology^1-3. Using a thinned-skull cortical window (TSCW), we employ spectral-domain OCT (SD-OCT) modality as a tool to image the cortex in vivo. Commonly, an opened-skull has been used for neuro-imaging as it provides more versatility, however, a TSCW approach is less invasive and is an effective mean for long term imaging in neuropathology studies. Here, we present a method of creating a TSCW in a mouse model for in vivo OCT imaging of the cerebral cortex.     

Brain estrogen signaling effects acute modulation of acoustic communication behaviors: A working hypothesis

Although estrogens are widely considered circulating “sex steroid hormones” typically associated with female reproduction, recent evidence suggests that estrogens can act as local modulators of brain circuits in both males and females. The functional implications of this newly characterized estrogen signaling system have begun to emerge. This essay summarizes evidence in support of the hypothesis that the rapid production of estrogens in brain circuits can drive acute changes in both the production and perception of acoustic communication behaviors. These studies have revealed two fundamental neurobiological concepts: (1) estrogens can be locally produced in brain circuits, independent of levels in nearby circuits and in the circulation and (2) estrogens can have very rapid effects within these brain circuits to modulate social vocalizations, acoustic processing, and sensorimotor integration. This vertebrate‐wide span of research, including vocalizing fishes, amphibians, and birds, emphasizes the importance of comparative model systems in understanding principles of neurobiology.     

Morphological characterisation of lactotrophs separated from the bovine pituitary by a rapid enrichment technique

Summary The morphological characteristics of bovine pituitary cells separated by a rapid enrichment procedure are described. Single-cell suspensions were prepared from pituitary glands of steers by use of a collagenase technique and separated by discontinuous gradient centrifugation. The separation of prolactin and growth hormone-containing cells was assessed by radioimmunoassay of hormone content and immunocytochemistry, and the distribution of fibroblasts assessed after establishing cell cultures. Morphometric analysis of the fine structure of two fractions respectively enriched and depleted in the proportion of immunocytochemically-identified lactotrophs was performed after labelling with anti-prolactin antiserum coupled to immunogold complex. Cells recovered from the higher-density fraction were more highly granulated, suggesting that this was a major characteristic determining separation. Cells labelled for prolactin could not be distinguished from unlabelled cells on the basis of their granule size range, but unlabelled cells had a significantly greater coefficient of variation. These data suggest that granule density and distribution, but not granule size per se, are useful characteristics for the identification of bovine lactotrophs.     

细胞松驰素B对牛传染性鼻气管炎病毒感染与复制的影响

体外培养的牛肾细胞,经浓度为50μg/ml的细胞松弛素B(CB)处理2小时后,牛传染性鼻气管炎病毒(IBRV)仍能侵入细胞,繁殖的子代病毒数量不受影响。然而当同样浓度的CB在病毒的整个繁殖期中持续存在时,病毒的繁殖即完全被抑制。说明细胞的吞噬作用至少不是这种病毒进入细胞的唯一方式,可能病毒囊膜与细胞膜的融合是病毒进入细胞的主要方式;而在侵入细胞后的病毒繁殖过程中,细胞微丝和其它对CB敏感的系统起着不可缺少的作用。降解微丝对IBRV的早期发生有明显的影响,其效应强度与CB的浓度有关。还观察到CB处理对病毒形态发生方式有明显影响。     

Comparison of the virulence of Trypanosoma congolense strains isolated from cattle in a trypanosomiasis endemic area of eastern Zambia

The virulence of 31 genetically different Trypanosoma congolense strains belonging to the Savannah subgroup and isolated from cattle at 11 sites in a trypanosomiasis endemic area of eastern Zambia was compared. Virulence testing, done in OF1 mice, revealed three virulence categories. Strains were considered extremely virulent when the median survival time ranged between 5 and 9 days. Moderately virulent strains had a median survival time between 10 and 30 days and low virulence, more than 30 days. For each strain, the prepatent period was determined and the PCV of the infected animals was measured at regular intervals. A total of six (19.4%) strains belonged to the extremely virulent category with a short prepatent period (mean 2.3+/-0.3 days), high parasitaemia, decline in PCV of 15.6+/-1.1% during the first 7 days p.i. and a short median survival time (mean 6 days). The remainder of the strains belonged to the moderate (13 strains) or low (12 strains) virulence categories with median survival times of 13 and 60 days, respectively. They had longer prepatent periods (means 3.2+/-1.6 days and 3.5+/-1.6 days for moderately virulent and strains with low virulence, respectively) and the decline in PCV was less steep (decline of 14.2+/-0.6 and 9.7+/-0.6% during the first 7 days of infection with moderately virulent strains and strains with low virulence, respectively). Extremely virulent strains were isolated from cattle at four sampling sites with 60% of the cattle from one sampling site harbouring such extremely virulent strains. Results from this study demonstrated substantial differences in the virulence of T. congolense strains of the Savannah subgroup, isolated in one geographic area from a single host species. On the assumption that information on virulence obtained from tests in mice can be extrapolated to cattle, the high proportion of strains with low to moderate virulence is thought to be attributed to the important role of susceptible cattle as reservoirs of trypanosomes in the study area and the ensuing selection against extremely virulent strains.