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Biomedical subjects

W Pflüger

Publications and source records attributed to W Pflüger.

10 recordsLinked to original sources
PubMed1984

The prepatent period and cercarial production of Schistosoma haematobium in Bulinus truncatus (Egyptian field strains) at different constant temperatures.

The developmental time of Schistosoma haematobium in Bulinus truncatus snails (field strains) was determined in the laboratory at different constant temperatures between 18 and 32 degrees C. The basic relationship between the length of the minimum prepatent period (y, in days) and the temperature (x, in degree C) is given by the hyperbolic formula y = 295/(x-15.3), 15.3 being the theoretical "developmental null point" and 295 the constant time-temperature product. The shortest prepatency was 17-19 days at 30, 31 and 32 degrees C; at 18 degrees C, cercarial development required at least 106-113 days. The maturation time frequently exceeded the possible minimum by several weeks. No schistosome matured in our experiments at 17 degrees or 33 degrees C. The cercarial release per snail at weekly exposures showed a maximum at 25 degrees C with a geometric mean of 109 cercariae (95% confidence limits 79-149), decreasing to 8 (2-30) at 18 degrees C and 62 (38-100) at 32 degrees C. The absolute maximum of cercariae shed by one snail during 5 h "stimulation" was 2,150 in a 25 degrees C batch, 48 at 18 degrees C and 529 at 32 degrees C. The epidemiological application, the prognosis of the transmission period and the estimation of the transmission potential in relation to climatic conditions are discussed.

Animals↗
PubMed1981

Experimental epidemiology of schistosomiasis. II. Prepatency of Schistosoma mansoni in Biomphalaria glabrata at diurnally fluctuating temperatures.

The basic hyperbolic relationship established between constant water temperatures and the length of the prepatent period in the snail was tested as diurnally fluctuating temperatures, stimulating natural conditions. Diurnal temperature variations are generally summed up by S. mansoni according to the time-temperature product and are independent of the shape of the temperature curve. Using a simple hyperbolic formula, the time of prepatency can be calculated for temperatures ranging from 16 degrees C to 32 degrees C. The developmental rate (reciprocal of the prepatency period) within this range is a linear function of the mean environmental temperature. Biomphalaria glabrata and S. mansoni survive well at temperature peaks as high as 40.5 degrees C or as low as 11.5 degrees C, if they are given as part of a diurnal sinusoidal or trapezoidal temperature programme. At fluctuating temperatures decreasing to low values of about 11 degrees to 14 degrees C, however, the parasite's development was up to 27% faster than predicted. Apparently the development in the low temperature range does not follow the basic hyperbolic relationship, and even below the so-called "developmental null point" of 14.2 degrees C some development of S. mansoni takes place. For practical purposes, an empirical compensation of the deviation at low temperatures is proposed. Instead of the real mean of the diurnal temperature cycle, the mean between 14.2 degrees C and the daily maximum can be used as the basis for calculation, regardless of the time with temperatures below 14.2 degrees C.

Animals↗
PubMed1980

Experimental epidemiology of schistosomiasis. I. The prepatent period and cercarial production of Schistosoma mansoni in Biomphalaria snails at various constant temperatures.

Laboratory experiments have permitted the quantification of the developmental times (prepatent periods) of Schistosoma mansoni in the snail over the whole possible range of constant temperatures. The basis relationship is satisfactorily described by a hyperbola of the formula y = 268/(x-14.2), y being the minimum time from miracidial infection to cercariae shedding (in days) x the mean temperature, and 14.2 the theoretical temperature threshold (in degrees C). Cercariae production takes place within the limits of +16 degrees C and 35 degrees C, the number of cercariae being low and the mortality of snails high at the extreme values. Long-term alternations between two temperature levels resulted in prepatent periods corresponding exactly to the proportional time-temperature products. However, slight accelerations of up to 7% and more could be observed when the prepatency began in a period of high temperature. The number of cercariae each snail shed during a period of one hour exposure per week decreased from about 1,500 at 18 degrees C to about 250 at 16 degrees C. Shedding ceased completely after 1-2 weeks at 15 degrees C.

Animals↗
PubMed1978

[On the usefulness of bone scintigraphy for detecting loosening of articular prostheses (author's transl)].

The most important complication of articular substitution is the loosening of the prostheses as a result of permanent overstraining, trauma, chemical or infectious noxae. The value of bone scintigraphy in the diagnosis of loosening of the endoprothesis was examined in 53 articular prostheses (49 hip joints and 4 knee joints). A pathological scan was evident in all cases where the prosthesis had become loose (18 cases), whereas a normal scan was found in 34 firmly positioned prostheses. A false positive scan occurred in one case of periarthritis. Bone scintigraphy can be employed as a means of diagnosing loosening of prostheses after a period of nine months following the operation; up to that time, enhancement can be due to the operation. A positive scan in case of loosening of the prosthesis is manifested earlier than radiological signs. For this reason, scintigraphy can be recommended as a routine examination method in pain after articular substitution surgery.

Bacterial Infections↗