Influence of vasoconstriction, temperature, and flow on the kinetics of serotonin uptake in rabbit lungs

In the process of estimating the kinetic parameters of the pulmonary endothelial serotonin (5-HT) uptake, it is critically important to distinguish the effects of hemodynamic changes from endothelial injury. Therefore, the effects of changes in flow rate (1.7-5.0 ml/s), hemodynamics (vasoconstriction by norepinephrine), and temperature (39 vs. 33 degrees C) were investigated in isolated rabbit lungs. Indicator-dilution data were expressed in terms of the Michaelis-Menten equation for the two 5-HT uptake pathways in the preparation. The maximum uptake velocity (Vmax1) and the 5-HT concentration at half-maximum velocity (Km1) of the first pathway as well as the first-order constant (Vmax2/Km2) of the linear part of the second pathway were determined. Neither vasoconstriction nor flow variations had any effect on Km1, whereas increasing the flow rate caused extensive recruitment, with a concomitant increase in Vmax1 and Vmax2/Km2. Furthermore, all the kinetic parameters were significantly decreased at the lower temperature. We conclude that Km1 is independent of organ hemodynamics (vasoconstriction and flow) but susceptible to changes in 5-HT uptake capacity caused by a change in temperature. Vmax1 and Vmax2/Km2 respond to alterations in 5-HT uptake capacity and perfused organ volume. These are prerequisites to apply kinetic modeling as a method for the investigation of pulmonary endothelial function and integrity.     

Relationship between the thyroidal and gonadal axes during the estrous cycle of ewes of different breeds and ages

In order to define the patterns of TSH, T4, T3, rT3, GH and cortisol during the estrous cycle of sheep, pluriparous and primiparous ewes were synchronized with progestagen-impregnated pessaries (Veramix) at the start of the normal breeding season. After the pessaries were removed (day 0), daily blood sampling was carried out in cannulated ewes during the ovulatory cycle. Hormonal analyses of TSH, T4, T3, rT3, GH, cortisol, LH and progesterone (P) were performed by RIA. P and LH levels during the cycle were conform to the literature and were not different between the primiparous and pluriparous ewes of different breeds used in this study. Neither age nor breed influenced the hormone patterns. A significant negative correlation was found between TSH and P during the cycle, although the correlation between P and T4 was not significant; during the estrous period, low P levels were paralleled by high T4 levels, whereas the reverse was observed during the luteal phase. Higher T3 levels and T3/T4 ratios were observed during the luteal phase. No obvious pattern of rT3 and cortisol during the cycle was found. The GH concentration increased during the 17 days of the cycle. A positive correlation with P was calculated. During the estrous cycle obvious changes in thyroid hormones, GH and TSH occurred. However, this study shows no causal relationship between the thyroid and the gonadal axes.     

Complete development of Cryptosporidium parvum in MDBK cells

Abstract Sporozoites of Cryptosporidium parvum excysted in vitro from bovine oocysts were incubated with monolayers of Madin-Darby bovine kidney cells. The extent of parasite colonisation was monitored by light microscopy and immunofluorescence. Electron microscopy confirmed the complete development and replication of C. parvum within Madin-Darby bovine kidney cells.     

“Wall-papering” and elaborate nest architecture in the ponerine antHarpegnathos saltator

Summary Excavation of 18 nests ofHarpegnathos saltator from southern India revealed an unusually complex architecture for a ponerine ant. The inhabited chambers are not deep in the ground. The uppermost chamber is protected by a thick vaulted roof, on the outside of which is an intervening space serving as isolation from the surrounding soil. In large colonies, the vaulted roof is extended into a shell which encloses several superimposed chambers. Little openings, which may be encircled by moulded flanges, occur in the upper region of the shell. The inside of the chambers is partly or completely lined with strips of empty cocoons. A refuse chamber is always found deeper than the inhabited chambers; live dipteran larvae (family Milichiidae) are typically present. These elaborate nests represent a large energetic investment, and we speculate therefore that nest emigration is unlikely in this species. Consequently, colony fission may never occur, unlike other ants where gamergates reproduce.     

Phytoplankton monitoring by flow cytometry

The application of flow cytometry to the monitoring of phytoplanktonis demonstrated. A comparison is made with conventional approachesto phytoplankton monitoring: light microscopy for the determinationof species abundance, and chlorophyll a determination and insitu chlorophyll a measurement by fluorescence for the determinationof the biomass. Flow cytometric measurements correlate wellwith these conventional types of measurements, as has been shownby comparing a full year of monitoring data obtained at a fixedmonitoring location 10 km off the Dutch coast. Flow cytometrybridges the gap between labour-intensive, but highly informative,microscopic observations and simple biomass measurements withless information content: via flow cytometry optical data areobtained at high speed for individual particles, which can betranslated into biomass information. On the basis of the flowcytometric measurements, rough discrimination of phytoplanktonspecies groups is possible, particularly for the abundant species.Of crucial importance is careful calibration of the flow cytometer,to ensure quantitative and comparable measurements over a longperiod of time. Calibration and quality assurance aspects arecovered in detail. ³Present address: Akzo Nobel Central Research Laboratories Arnhem,Department CRL, PO Box 9300, NL-6800 SB Arnhem, The Netherlands     

The phenotype of some late-flowering mutants is enhanced by a locus on chromosome 5 that is not effective in the Landsberg erecta wild-type

Late-flowering mutants that have been described in ecotypes other than Landsberg erecta (Ler) have been found to be dominant alleles of the FRI locus located on chromosome 4, which determines lateness in many very late ecotypes. The extreme lateness of dominant FRI alleles depends on dominant alleles at the FLC locus that maps on the top of chromosome 5. FLC alleles with this effect have been found in all ecotypes tested (Col, Ws, S96, Est and Li) except Ler. Most likely the same locus confers lateness to the luminidependens (ld) mutant. Genotypes with a dominant FRI allele and the monogenic recessive ld mutant are only slightly later with recessive Ler alleles at the FLC locus. Genotypes where the dominant FLC alleles are combined with FRI or with the ld mutant, are strongly responsive to vernalization, which is much less effective in the FLC-Ler background.     

The periodicities in and biometeorological relationships with bed occupancy of an acute psychiatric ward in Antwerp,Belgium

Recently, some investigators have established a seasonal pattern in normal human psychology, physiology and behaviour, and in the incidence of psychiatric psychopathology. In an attempt to elucidate the chronopsy and meteotropism in the latter, we have examined the chronograms of, and the biometeorological relationships to bed occupancy of the psychiatric ward of the Antwerp University Hospital during three consecutive calendar years (1987–1989). Weather data for the vicinity were provided by a local meteorological station and comprise mean atmospheric pressure, air temperature, relative humidity, wind speed and minutes of sunlight and precipitation/day. The number of psychiatric beds occupied during the study period exhibited a significant seasonal variation. Peaks in bed occupancy were observed in March and November, with lows in August. An important part of the variability in the number of beds occupied could be explained by the composite effects of weather variables of the preceding weeks. Our results suggest that short-term fluctuations in atmospheric activity may dictate some of the periodicities in psychiatric psychopathology.     

Characterization of IS1001, an insertion sequence element of Bordetella parapertussis.

By analysis of repetitive DNA in Bordetella parapertussis, an insertion sequence element, designated IS1001, was identified. Sequence analysis revealed that IS1001 comprised 1,306 bp and contained inverted repeats at its termini. Furthermore, several open reading frames that may code for transposition functions were identified. The largest open reading frame coded for a protein comprising 406 amino acid residues and showed homology to TnpA, which is encoded by an insertion sequence element (IS1096) found in Mycobacterium smegmatis. Examination of flanking sequences revealed that insertion of IS1001 occurs preferentially in stretches of T's or A's and results in a duplication of target sequences of 6 to 8 bases. IS1001 was found in about 20 copies in 10 B. parapertussis strains analyzed. No restriction fragment length polymorphism was observed in B. parapertussis when IS1001 was used as a probe. An insertion sequence element similar or identical to IS1001 was found in B. bronchiseptica strains isolated from pigs and a rabbit. In these strains, about five copies of the IS1001-like element were present at different positions in the bacterial chromosome. Neither B. pertussis nor B. bronchiseptica strains isolated from humans and dogs contained an IS1001-like element. Therefore, IS1001 may be used as a specific probe for the detection of B. parapertussis in human clinical samples.     

Study of the dynamics of neutralization escape mutants in a chimpanzee naturally infected with the simian immunodeficiency virus SIVcpz-ant.

Here we report on the use of spectral map analysis of time-paired sequential neutralization data of 11 serum samples of a chimpanzee naturally infected with a simian immunodeficiency virus (SIVcpz-ant) and 8 primary consecutive SIVcpz-ant isolates, taken at about 4-month intervals. The analysis reveals the existence of three SIVcpz-ant isolate and serum neutralization clusters. Each cluster groups virus isolates and/or sera based on similarities of their neutralization spectra. On average, neutralization escape mutants emerged after 15 months and mounted a neutralization response approximately 8 months later. The entire gp160 regions of eight consecutive isolates were sequenced and analyzed by a new statistical method called polygram, which allowed the deduction of amino acid sequence motifs of gp160 which were specific for SIVcpz-ant isolates belonging to the same isolate neutralization clusters. Changes in specific amino acid quadruplets in V1, V2, C3, V4, V5, and CD4 domains of gp120 and gp40 were seen to correlate with the neutralization clusters with most of the specific changes occurring in the V4 region. This method of analysis may facilitate an understanding of the study of the dynamic interplay between human immunodeficiency virus (HIV) and host neutralization responses as well as providing possible insights into mechanisms of persistence of HIV-1-related lentiviruses in their natural hosts.