The impact of the Department of Phytopathology at the Wageningen Agricultural University, as evaluated by citation analysis

The results of a citation analysis of all publications by the Department of Phytopathology which appeared in the period 1969–1987, but based on citations recorded by the Science Citation Index only, are presented. Together with the results of an analysis of self-citations by the eight most cited authors they suggest, that phytopathology as a science is poorly covered by the Science Citation Index.Een citatie-analyse van alle in de periode 1969–1987 verschenen publikaties van de Vakgroep Fytopathologie omvatte uitsluitend citaties voorzover vermeld in de Science Citation Index (SCI).Enkele vermeldenswaardige resultaten betreffen de krommen, die de cumulatieve citatie-aantallen weergeven (Figuren 1b en 2b) en de grafiek, die de relatieve bijdrage van uiteenlopende publikaties aan het totaal der citaties uitbeeldt (Fig. 3). Uit Fig. 2b blijkt, dat het citatieverloop van een gemiddelde publikatie het karakter van een logistische groeikromme vertoont: na een lagfase en een fase van exponentiële groei vlakt de kromme at naar een stationaire fase. Uit Fig. 3 kan worden afgeleid, dat weinig artikelen veel, en vele weinig tot het totale aantal citaties bijdragen; zo nemen 25 van de in totaal 321 geciteerde artikelen 50% van het totale aantal (3659) citaties voor hun rekening!     

Inflammation and increased numbers of bacteria in the lower respiratory tract of horses within 6 to 12 hours of confinement with the head elevated

SUMMARY: Confinement of horses with their heads elevated for periods up to 24 hours was used to evaluate the extent and the effects of bacterial contamination of the equine lower respiratory tract. Significant (P < 0.05) increases in bacterial numbers (up to 10⁹ colony forming units/mL in transtracheal aspirate derived samples) occurred within 6 or 12 hours in most horses. Pasteurella/Actinobacillus spp and Streptococcus spp were most commonly isolated. Lowering of the head for 30 minutes every 6 hours to facilitate postural drainage did not prevent multiplication of organisms to levels equivalent to those achieved by horses where the head was elevated for 24 hours. When horses were released from confinement and heads were no longer maintained in an elevated position, clearance of accumulated secretions and bacteria occurred within 8 to 12 hours. Thus, confinement with the head elevated resulted in significant bacterial contamination and multiplication within the lower respiratory tract during a period often encountered in routine management procedures, such as transportation. The clearance of accumulated secretions occurred over a prolonged period after release from such confinement.     

Insulin sensitivity decreases with obesity, and lean cats with low insulin sensitivity are at greatest risk of glucose intolerance with weight gain

This study quantifies the effects of marked weight gain on glucose and insulin metabolism in 16 cats which increased their weight by an average of 44.2% over 10 months. Significantly, the development of feline obesity was accompanied by a 52% decrease in tissue sensitivity to insulin and diminished glucose effectiveness. In addition, glucose intolerance and abnormal insulin response occurred in some cats. An important finding was that normal weight cats with low insulin sensitivity and glucose effectiveness were at increased risk of developing impaired glucose tolerance with obesity. High basal insulin concentrations or low acute insulin response to glucose also independently increased the risk for developing impaired glucose tolerance. Male cats gained more weight relative to females and this, combined with their tendency to lower insulin sensitivity and higher insulin concentrations, may explain why male cats are at greater risk for diabetes. Results suggest an underlying predisposition for glucose intolerance in some cats, which is exacerbated by obesity. These cats may be more at risk of progressing to overt type 2 diabetes mellitus.     

Hide and seek – Infection rates and alkaloid concentrations of Epichloë festucae var. lolii in Lolium perenne along a land‐use gradient in Germany

The common forage grass Lolium perenne has evolved with the systemic fungal endophyte Epichloë festucae var. lolii. The endophyte provides herbivore resistance to the grass due to defensive alkaloids, some of which are toxic to grazing livestock. In this field study, we determine whether distribution of the endophyte‐grass association changes along a land‐use intensity gradient on 87 managed grasslands in three German regions. Endophyte infections were detected in 66% of the studied sites and infection rates within infected sites ranged from 1% to 95%. Alkaloid concentrations of lolitrem B (vertebrate toxin) exceeded the toxicity thresholds in 50 (14%) of 351 infected plants and of peramine (invertebrate deterrent/toxin) in 12 (3%) of 351 plants. Infection rates and alkaloid concentrations were not significantly affected by land‐use intensity and region, but alkaloid concentrations were higher in summer compared to spring. We conclude that risks for livestock intoxication are currently low, as (i) average alkaloid concentrations per grassland were always below toxicity thresholds and as (ii) none of the grasslands was dominated by L. perenne. We suggest avoidance of grass monocultures in Europe to keep intoxication risks for livestock low; we also recommend regular examination of seeds and grasslands, as seed producers might accidentally distribute infected seeds, and as climate warming might further enhance the distribution of Epichloë endophytes in European grasslands.     

Use of variograms to detect critical spatial distances for the Knox's test

We aimed to find critical spatial distances (as an input quantity for the Knox's test) using geostatistical methods. The spatiotemporal data set included all individual-chamois cases of scabies observed in Styrian chamois populations in 137 of 2837 game preserves in Styria (a province in the south of Austria) over the time period between 1952 and 1998. Theoretical variogram models were fitted to empirical variograms, which were calculated for cycles of 5 years. The unit of analysis was the mean quadratic deviation between individual-chamois cases of scabies. The "range" (which represents the transition from the state in which spatial correlation exists to the state in which there is absence of spatial correlation) was used as an indicator for the critical spatial distance for the Knox's test. The critical distances for the 5-year cycles varied between 10.8 and 16.0 km. If the time of observation is not considered, the critical "overall" distance amounted to 13.5 km.     

Detection of space-time clusters and epidemiological examinations of scabies in chamois

In this paper some methodological approaches towards the detection of temporal, spatial and space-time clusters are presented and discussed in context with epidemiological factors of scabies in chamois. This presentation comprises in particular the use of the Scan Test (Wallenstein, 1980) for the detection of temporal clusters and the tests developed by Knox (1964) and Mantel (1967) for the testing of spatiotemporal interactions. Between 1952 and 1998 a total of 1689 cases of scabies in chamois and six cases in ibex were documented in 137 game preserves of the Austrian province of Styria. The evaluations indicate the presence of spatial and temporal clusters. Some possibilities for the spread of scabies in chamois are presented and reveal ibex as a probable vector for scabies transmission between chamois populations. The information may lead to strategies for controlling the spread of the disease.     

Bronchoalveolar lavage in horses: effect of exercise and repeated sampling on cytology

SUMMARY Bronchoalveolar lavage (BAL) was performed at weekly intervals in 10 Thoroughbred horses in race training (group 1) and in 4 rested horses (group 2) for 10 weeks. Lavages were continued on a weekly basis in 4 group 1 horses for an additional 9 weeks (group 3). Cytological analysis of samples included leukocyte counts, erythrocyte counts, differential leukocyte counts, and haemosiderophage score. The mean leukocyte concentration was significantly lower in group 1(92.1 ± 4.6 cells/μL) when compared with group 2 (133.5 ± 8.2 cells/μL), P = 0.037. The differential leukocyte data were not significantly different between groups. There was a large amount of variability in the percent-age of macrophages and lymphocytes in the differential counts over time with no obvious trends. The proportion of neutrophils demonstrated a tendency to decrease over time for both groups 1 and 2. Erythrocyte counts and haemosiderin scores were significantly higher in the exercising group than the rested horses. Neither exercise nor the technique itself evoked an inflammatory response in the BAL fluid.     

T-shaped malformation of the ventral colon in a Thoroughbred filly with colic

A 4-month-old Thoroughbred filly presented for abdominal pain was diagnosed with a T-shaped malformation of the ventral colon at exploratory laparotomy. Following resection and anastomosis of the large colon, no further episodes of abdominal pain occurred during a 12-month follow-up. Acute dehiscence of the linea alba occurred as a complication of the initial laparotomy, but was successfully managed following additional surgical repair. T-shaped malformation of the ventral colon has not previously been reported and is considered a congenital malformation of mesocolon formation.