Pulmonary gas exchange in panting dogs

Pulmonary gas exchange during panting was studied in seven conscious dogs (32 kg mean body wt) provided with a chronic tracheostomy and an exteriorized carotid artery loop. The animals were acutely exposed to moderately elevated ambient temperature (27.5 degrees C, 65% relative humidity) for 2 h. O2 and CO2 in the tracheostomy tube were continuously monitored by mass spectrometry using a special sample-hold phase-locked sampling technique. PO2 and PCO2 were determined in blood samples obtained from the carotid artery. During the exposure to heat, central body temperature remained unchanged (38.6 +/- 0.6 degrees C) while all animals rapidly switched to steady shallow panting at frequencies close to the resonant frequency of the respiratory system. During panting, the following values were measured (means +/- SD): breathing frequency, 313 +/- 19 breaths/min; tidal volume, 167 +/- 21 ml; total ventilation, 52 +/- 9 l/min; effective alveolar ventilation, 5.5 +/- 1.3 l/min; PaO2, 106.2 +/- 5.9 Torr; PaCO2, 27.2 +/- 3.9 Torr; end-tidal-arterial PO2 difference [(PE' - Pa)O2], 26.0 +/- 5.3 Torr; and arterial-end-tidal PCO2 difference, [(Pa - PE')CO2], 14.9 +/- 2.5 Torr. On the basis of the classical ideal alveolar air approach, parallel dead-space ventilation accounted for 54% of alveolar ventilation and 66% of the (PE' - Pa)O2 difference. But the steepness of the CO2 and O2 expirogram plotted against expired volume suggested a contribution of series in homogeneity due to incomplete gas mixing.     

Degradation of juvenile hormone and methylation of juvenile hormone acid by corpora cardiaca–corpora allata of the cockroach,Nauphoeta cinerea: II. Physiological aspects

In vitellogenic females of Nauphoeta cinerea, injected (10R)-juvenile hormone (JH) III was degraded more rapidly than racemic JH III: we measured a half-life of 21 min (with or without coinjection of lipophorin) for the former and 24 min (with coinjection of lipophorin) and 43 min (without coinjection of lipophorin) for the latter. One to two hours after injection, JH III acid was the major metabolite observed; in addition, several highly polar products were found. The half-life of injected racemic JH III acid was 19 min with coinjection of lipophorin and 4 min without. The JH III acid titer in hemolymph was low (around 5–10 pmol/ml) in last instar larvae and previtellogenic and pregnant females and reached higher values (40–100 pmol/ml) in vitellogenic and ovulating females. Racemic JH III acid could be methylated in vitro to JH III by corpora cardiaca–corpora allata (CC-CA) from penultimate instar larvae and females at stages between adult ecdysis and ovulation and at the very end of pregnancy, but not by CC-CA from last instar larvae and adult females at earlier stages of pregnancy. This indicates that CC-CA are capable of methylating JH III acid only at stages when JH III is detectable in the hemolymph. In double-labelling experiments with CC-CA from vitellogenic females and L-[¹⁴C]methionine and [³H]JH III acid as precursors, we observed that only a small proportion (1–8%) of total biosynthesized JH III was derived from JH III acid when the latter was present at physiological concentration. This suggests that in vivo recycling of JH III acid by CC-CA plays only a minor role in the regulation of the titer of JH III and JH III acid.     

A vivid model of chiral recognition

Hands can be used to demonstrate the three-point model of chiral recognition. The points of attachment are thumb, forefinger, and middle finger. This vivid model has the advantages of simplicity, perspicuity, and availability at any time, although two persons are necessary. It can be shown that two interactions are not sufficient for chiral recognition but that three attractive or two attractive and one repulsive attraction are needed. It can also be used to explain some possibilities of weakening or elusion of the three-point model.     

Two colour DNA in situ hybridization for the detection of two viral genomes using non-radioactive probes

Summary Methods for the simultaneous detection of two virus types in cytological preparations or tissue sections by non-radioactive in situ hybridization were investigated. As a model system, CaSki cells, which have human papilloma virus type 16 (HPV 16) DNA integrated in their cellular genome, were in vitro infected with Herpes simplex virus 2 (HSV2). DNA probes for both viruses were labeled with biotin, acetylaminofluorene (AAF), and transaminated-sulfonated cytosine (TS-modified). Best results were obtained when a mixture of biotinated and haptenized DNA probes (AAF-or TS-modified) was used for hybridization. The biotinated hybrid was demonstrated with a streptavidinbiotinated alkaline phosphatase staining reaction, whereas the haptenized hybrid was visualized by an indirect peroxidase method. Visualisation of both viral DNAs in the same cell was possible by a combination of biotinated HPV 16 DNA and haptenized HSV2 DNA.     

Regional and cellular codistribution of interleukin 1 beta and nerve growth factor mRNA in the adult rat brain: possible relationship to the regulation of nerve growth factor synthesis

We have found a regional distribution of IL 1 beta mRNA and IL 1 activity in the normal adult rat brain, which reveals at least partially a colocalization with nerve growth factor (NGF). The predominantly neuronal signal patterns were found over the granule cells of the dentate gyrus, the pyramidal cells of the hippocampus, the granule cells of the cerebellum, the granule and periglomerular cells of the olfactory bulb, and over dispersed cells of the ventromedial hypothalamus and of the frontal cortex. In these areas also the highest levels of IL 1 activity were observed. In the striatum and septum much lower levels of IL 1 beta mRNA and IL 1 activity (shown for the striatum), most likely synthesized by glial cells, could be determined. IL 1 beta-expressing cells were mainly found in brain regions that also synthesize NGF mRNA as shown by in situ hybridization. NGF mRNA could be demonstrated over pyramidal cells of the hippocampus, granule cells of the dentate gyrus, periglomerular cells of the olfactory bulb and over prefrontal cortex neurons. These data indicate that IL 1 beta, among other factors, might also play a regulatory role in the synthesis of NGF in the CNS, as has been demonstrated in the peripheral nervous system (Lindholm, D., R. Heumann, M. Meyer, and H. Thoenen. 1987. Nature (Lond.). 330:658-659).     

Membrane biogenesis during B cell differentiation: most endoplasmic reticulum proteins are expressed coordinately

The induction of high-rate protein secretion entails increased biogenesis of secretory apparatus organelles. We examined the biogenesis of the secretory apparatus in the B cell line CH12 because it can be induced in vitro to secrete immunoglobulin (Ig). Upon stimulation with lipopolysaccharide (LPS), CH12 cells increased secretion of IgM 12-fold. This induced secretion was accompanied by preferential expansion of the ER and the Golgi complex. Three parameters of the rough ER changed: its area and volume increased 3.3- and 3.7-fold, respectively, and the density of membrane-bound ribosomes increased 3.5-fold. Similarly, the area of the Golgi stack increased 3.3-fold, and its volume increased 4.1-fold. These changes provide sufficient biosynthetic capacity to account for the increased secretory activity of CH12. Despite the large increase in IgM synthesis, and because of the expansion of the ER, the concentration of IgM within the ER changed less than twofold during the differentiation process. During the amplification of the rough ER, the expression of resident proteins changed according to one of two patterns. The majority (75%) of rough microsomal (RM) proteins increased in proportion to the increase in rough ER size. Included in this group were both lumenal proteins such as Ig binding protein (BiP), and membrane proteins such as ribophorins I and II. In addition, the expression of a minority (approximately 9%) of RM polypeptides increased preferentially, such that their abundance within the RM of secreting CH12 cells was increased. Thus, the expansion of ER during CH12 differentiation involves preferential increases in the abundance of a few resident proteins, superimposed upon proportional increases in most ER proteins.     

Extraction of melodies in behavioural sequences

A method is proposed that extracts a set of phrases, or “melodies”, from a behavioural sequence, using a technique for extracting and compressing chains based on Information Theory. These melodies are validated by reference to a statistical criterion. An application of this method to the analysis of the behavioural sequences of two groups of mice, the first observed during the day, the second during the night, is described. The advantages and the limitations of the method are discussed.     

Different long-term effects of bilateral and unilateral nucleus basalis lesions on rat cerebral cortical neurotransmitter content

Young adult rats received either unilateral or bilateral ibotenic acid infusions in their nucleus basalis, destroying most of the cholinesterase-staining neurons in that region. Cerebral cortex levels of choline acetyltransferase, somatostatin, neuropeptide Y, and monoamines were then assayed 2.5 and 10 months after bilateral lesions, or, 2.5, 10, and 14 months after unilateral lesions. Entorhinal and cerebral cortex levels of several amino acid transmitters were also measured. As expected, choline acetyltransferase activity was decreased in the frontal cortex ipsilateral to the ibotenic acid infusion in unilaterally or bilaterally lesioned animals. Parietal cortex concentrations of somatostatin and neuropeptide Y were altered by lesioning in a complicated, time-dependent manner. Thus, while unilateral lesions transiently decreased or had no effect on these neuropeptide levels, bilateral lesions elevated the level of each neuropeptide by over 100% at 10 months. Other cortical transmitter systems investigated appeared to be less affected by nucleus basalis-lesions. Unilateral lesions had no effect on prefrontal cortex norepinephrine, serotonin, or dopamine content at 14 months post-lesioning. These different neurochemical effects of unilateral and bilateral nucleus basalis lesions may be important for developing a model for the trans-synaptic effects of cortical cholinergic deafferentation.     

吗啡耐受大鼠心房心钠素的释放及其基因转录

本工作应用心钠素放射免疫测定和分子杂交技术首次发现,吗啡耐受大鼠血浆心钠素水平显著降低,心房内心钠素含量明显升高,同时心房内心钠素特异性mRNA水平也相应提高,提示在吗啡耐受时大鼠心房内心钠素的合成和贮存增加,释放减少。     

Histochemical study on the eccrine glands in the foot pad of the cat

Enzyme and carbohydrate histochemical methods were used to study the secretory activities and secretion properties of the eccrine tubular glands in the foot pad of the cat. The activity spectra of the different oxidative and hydrolytic enzymes investigated indicate high metabolic rates within the secretory epithelium. Additionally the enzyme reactions emphasize a double innervation of the glands by cholinergic and adrenergic nerve fibres. The carbohydrate histochemical differentiation reveals mostly neutral and very few acidic glycoproteins in the secretory cells and the secretion, respectively. Clear (basal) cells contain distinct amounts of glycogen, and dark (superficial) cells show neutral glycoproteins, which reveal after PO-lectin-DAB procedures the following saccharide residues: alpha-D-mannose, alpha-D-galactose, N-acetyl-alpha-D-glucosamine, alpha-L-fucose, beta-D-galactose-D-N-galactosamine, beta-D-galactose, and sialic acid. The results obtained confirm the view that the normal biological functions of the eccrine glands of the feline foot pad are to improve the frictional capacities of the paw and to leave typical scent marks.