Relationships between the phagocytic ability of milk macrophages and polymorphonuclear cells and somatic cell counts in uninfected cows

Phagocyte numbers and activities were compared in milk from 2 groups of uninfected mammary-gland quarters from 3 cows each: 6 quarters with a high (> or = 200 000/mL) somatic cell concentration (SCC), analyzed as 4 individual quarters and 1 pooled sample; and 12 quarters with a low SCC (< 200 000/mL), analyzed as 6 paired samples. The concentrations and ability of macrophages and polymorphonuclear (PMN) cells to phagocytize fluorescent microspheres were determined by flow cytometry after exposure of the cells to the microspheres. The macrophages and PMNs contained 2 major subpopulations, characterized by low phagocytic (LP) or high phagocytic (HP) ability. The quarters with high SCCs had significantly lower percentages of HP cells than did the quarters with low SCCs (P < 0.01). Whether mammary-gland quarters or cows were the unit of analysis, the HP/LP ratio was negatively related to the SCC (P < 0.04), which explained more than 50% of the SCC variability. Thus, poor bovine mammary-gland phagocytic ability may be associated with high SCC. Longitudinal studies are suggested to further explore and characterize these relationships.     

Multifactorial relationships between intramammary invasion by Staphylococcus aureus and bovine leukocyte markers

We explored the hypothesis that the outcome of bacterial invasion (infection or no infection) may depend on immunologic factors when bacterial and environmental factors are kept constant. Leukocyte surface molecules (CD3, CD2, CD4, CD8, CD11b, and CD45r) were assessed before and 3 times after intramammary infusion of Staphylococcus aureus in 5 dairy cows. The somatic cell count (SCC/mL), bacterial count (colony-forming units [CFUs]/mL), ratio of milk phagocytes (mononuclear [Mphi] plus polymorphonuclear [PMN] cells) to lymphocytes (P/L index), and ratio of PMN to Mphi cells (PMN/Mphi index) were determined. Although all cows showed evidence of inflammation resulting from the infusion (the median P/L ratio was 11 times greater 1 d after infusion than before infusion), bacteria were not obtained from the milk of 2 cows. Threshold-like responses, resulting in bacterial counts that approached zero (indicating no infection) and SCCs of less than 500000/mL, were observed when the milk CD2+ lymphocyte proportion exceeded 73% (P < or = 0.007). At 1 d after infusion, 7 immune factors distinguished infected cows from those without infection with more than 95% confidence: compared with infected cows, uninfected cows had higher proportions of CD3+, CD2+, CD4+, and CD8+ T cells, higher densities of CD3 and CD2 molecules per cell, and a higher density of CD11b molecules on milk Mphi cells. At 7 d after infusion, the PMN/Mphi index was lower (94% confidence) in uninfected than in infected cows. At 14 d, the CD2, CD8, and CD45r marker densities were lower than those at 1 d (P < 0.02), findings compatible with memory function. Synergism was suggested by the combined effects of the proportions of CD3+, CD2+, and CD11b+ cells, which explained 75.5% of the bacterial-count variability (P < 0.001); alone, none of these markers predicted CFU variability. These results support further studies aimed at identifying cows capable (or incapable) of early bacterial clearance.     

Species diversity,population dynamics and spatial distribution of mites on blackberry (Rubus ulmifolius Schott): A comparison between organic and conventionally-managed orchards

Phytoparasitica - We studied the species diversity of mites in five blackberry orchards [Rubus ulmifolius Schott (Rosales:Rosaceae)], three using organic production techniques and two conventional....     

Comparison of the effects of caffeine and doxapram on respiratory and cardiovascular function in foals with induced respiratory acidosis

OBJECTIVE: To determine and compare the effects of caffeine and doxapram on cardiorespiratory variables in foals during isoflurane-induced respiratory acidosis. ANIMALS: 6 clinically normal foals (1 to 3 days old). PROCEDURES: At intervals of > or = 24 hours, foals received each of 3 IV treatments while in a steady state of hypercapnia induced by isoflurane anesthesia (mean +/- SD, 1.4 +/- 0.3% endtidal isoflurane concentration). After assessment of baseline cardiorespiratory variables, a low dose of the treatment was administered and variables were reassessed; a high dose was then administered, and variables were again assessed. Sequential low- and high-dose treatments included doxapram (loading dose of 0.5 mg/kg, followed by a 20-minute infusion at 0.03 mg/kg/min and then 0.08 mg/kg/min), caffeine (5 mg/kg and 10 mg/kg), and saline (0.9% NaCl) solution (equivalent volumes). RESULTS: Administration of doxapram at both infusion rates resulted in a significant increase in respiratory rate, minute ventilation, arterial blood pH, PaO(2), and arterial blood pressure. These variables were also significantly higher during doxapram administration than during caffeine or saline solution administration. There was a significant dose-dependent decrease in PaCO(2) and arterial bicarbonate concentration during doxapram treatment. In contrast, PaCO(2) increased from baseline values after administration of saline solution or caffeine. The PaCO(2) value was significantly lower during doxapram treatment than it was during caffeine or saline solution treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that doxapram restored ventilation in a dose-dependent manner in neonatal foals with isoflurane-induced hypercapnia. The effects of caffeine on respiratory function were indistinguishable from those of saline solution.     

Measuring landscape connectivity: On the importance of within-patch connectivity

Context

Many connectivity metrics have been used to measure the connectivity of a landscape and to evaluate the effects of land-use changes and potential mitigation measures. However, there are still gaps in our understanding of how to accurately quantify landscape connectivity.

Objectives

A number of metrics only measure between-patch connectivity, i.e. the connectivity between different habitat patches, which can produce misleading results. This paper demonstrates that the inclusion of within-patch connectivity is important for accurate results.

Methods

The behavior of two metrics is compared: the Connectance Index (CONNECT), which measures only between-patch connectivity, and the effective mesh size (m_eff), which includes both within-patch and between-patch connectivity. The connectivity values of both metrics were calculated on a set of simulated landscapes. Twenty cities were then added to these landscapes to calculate the resulting changes in connectivity.

Results

We found that when using CONNECT counter-intuitive results occurred due to not including within-patch connectivity, such as scenarios where connectivity increased with increasing habitat loss and fragmentation. These counter-intuitive results were resolved when using m_eff. For example, landscapes with low habitat amount may be particularly sensitive to urban development, but this is not reflected by CONNECT.

Conclusions

Applying misleading results from metrics like CONNECT can have detrimental effects on natural ecosystems, because reductions in within-patch connectivity by human activities are neglected. Therefore, this paper provides evidence for the crucial need to consider the balance between within-patch connectivity and between-patch connectivity when calculating the connectivity of landscapes.

     

Effects of different artificial photoperiods and temperatures on haematological parameters of rainbow trout (Oncorhynchus mykiss)

This study assessed the effects of two artificial photoperiods (LD 24:0 and LD 12:12) and three temperature regimes (9, 11, and 18°C) for 30 days on haematological parameters of trout (Oncorhynchus mykiss) kept in freshwater. Samples were taken at days 7, 14, and 30 during exposure to treatments. A higher mortality (22%) and lower oxygen concentration (<8.0 mg/l) were associated with the combination of photoperiod LD 24:0 and 18°C. The LD 24:0 photoperiod (independently of temperature) increased the haematocrit and the number of erythrocytes at days 7, 14, and 30 (P < 0.01). A temperature of 18°C (independently of photoperiod regimes) diminished the number of total leucocytes, lymphocytes and thrombocytes (P < 0.01). The LD 24:0 photoperiod (also independently of temperature) lowered the number of lymphocytes only after 14 days of experimentation (P < 0.01). Interaction between artificial photoperiod and temperature was only observed at day 14 for polychromatophils (P < 0.01). These results resemble the effects of stress caused by elevated temperatures and the application of continuous light photoperiods, indicating that survival risks may develop in trout farming when this combination is met.     

Temporal sequence of cell wall disassembly events in developing fruits. 1. Analysis of raspberry (Rubus idaeus)

Raspberry fruits were harvested at five developmental stages, from green to red ripe, and the changes in cell wall composition, pectin and hemicellulose solubilization, and depolymerization were analyzed. Fruit softening at intermediate stages of ripening was associated with increased pectin solubilization, which occurred without depolymerization. Arabinose was found to be the most abundant noncellulosic neutral sugar in the cell wall and showed dramatic solubilization late in ripening. No changes in pectin molecular size were observed even at the 100% red stage. Subsequently, as fruit became fully ripe a dramatic depolymerization occurred. In contrast, the hemicellulosic fractions showed no significant changes in content or polymer size during ripening. The paper discusses the sequence of events leading to cell wall disassembly in raspberry fruit.     

Identification of case clusters and counties with high infective connectivity in the 2001 epidemic of foot-and-mouth disease in Uruguay

OBJECTIVE: To evaluate the influence of individual spatial units (ie, counties) on the epidemic spread of foot-and-mouth disease (FMD) virus. SAMPLE POPULATION: 163 counties in Uruguay where there was an outbreak of FMD between April 23 and July 11, 2001. PROCEDURE: A geographically referenced database was created, and the distance between counties (13,203 county pairs), road density of counties (163 counties), and time when cases were reported in those counties (11 weeks of the epidemic) were considered to assess global spatial and spatial-temporal autocorrelation, determine the contribution of links connecting pairs of counties with infected animals, and allow us to hypothesize the influence for spread during the epidemic for counties with greater than the mean infective link contributions. RESULTS: Case clusters were indicated by the Moran Iand Mantel tests during the first 6 weeks of the epidemic. Spatial lags between pairs of counties with infected animals revealed case clustering before and after vaccination was implemented. Temporal lags predicted autocorrelation for up to 3 weeks. Link indices identified counties expected to facilitate epidemic spread. If control measures had been implemented in counties with a high index link (identifiable as early as week 1 of the epidemic), they could have prevented (by week 11 of the epidemic) at least 2.5 times as many cases per square kilometer than the same measures implemented in counties with average link indices. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of spatial autocorrelation and infective link indices may identify network conditions that facilitate (or prevent) disease spread.     

Transcrystalline melt migration and Earth's mantle

Plate tectonics and volcanism involve the formation, migration, and interaction of magma and gas. Experiments show that melt inclusions subjected to a thermal gradient migrate through olivine crystals, under the kinetic control of crystal-melt interface mechanisms. Exsolved gas bubbles remain fixed and eventually separate from the melt. Scaled to thermal gradients in Earth's mantle and geological times, our results account for the grain-scale segregation of primitive melts, reinterpret CO2-rich fluid inclusions as escaped from melt, and question the existence of a free, deeply percolating fluid phase. Melt migration experiments also allow us to quantify crystal growth kinetics at very low undercoolings in conditions appropriate to many natural systems.