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Biomedical subjects

D L Kline

Publications and source records attributed to D L Kline.

At least 55 records · Page 3Linked to original sources
PubMed1985

Laboratory evaluation of four organophosphate compounds as larvicides against field collected salt marsh Culicoides spp. (Diptera: Ceratopogonidae).

The relative effectiveness of 4 organophosphate compounds was tested in the laboratory against Culicoides spp. larvae obtained from salt marsh areas on the Gulf coast of Florida. Larvae were exposed to the insecticide either in estuarine water or in a combination of estuarine water and dried substrate from the salt marsh habitat. The relative potency of the 4 chemicals varied greatly, with chlorpyrifos being the most toxic. Nine times as much temephos, 22 times as much fenthion, and 176 times as much malathion were required to achieve the 50% mortality level compared to chloryprifos (LC50, 0.5 ppb) in water. Addition of habitat soil did not change the order of effectiveness, but 9 times as much chlorpyrifos, 2.3 times as much temephos, and 1.3 times as much fenthion or malathion were required to cause the same mortality as in estuarine water alone.

Animals↗
PubMed1985

Observations on larval habitats of suspected Culicoides vectors of bluetongue virus in Florida.

Potential breeding sites for Culicoides variipennis (Coquillett) and C. insignis Lutz, suspected vectors of bluetongue virus (BTV) in Florida, were examined at 7 livestock facilities located in different geographic regions of the state. The 2 most productive habitats were mud contaminated by effluent from milking parlors (92.3 larvae/sample) and margins of vegetated ponds (18.8 larvae/sample). Four species of biting midges, C. crepuscularis Malloch, C. haematopotus Malloch, C. insignis, and C. variipennis were reared from immature stages extracted from substrate samples. Culicoides insignis was recovered from samples taken from muddy areas in pastures and margins of vegetated ponds, whereas C. variipennis was collected around waste lagoons and from mud contaminated by effluent from milking parlors.

Animals↗
PubMed1984

The effectiveness of permethrin and deet, alone or in combination, for protection against Aedes taeniorhynchus.

Field tests were conducted to compare the degree of protection from bites by the mosquito Aedes taeniorhynchus (Wiedemann) provided by wearing clothing treated with permethrin [(3-phenoxyphenyl)methyl (+/-) cis/trans 3-(2-dichloroethenyl)2, 2-dimethylcyclopropanecarboxylate] with that provided by applying deet (N,N-diethyl-m-toluamide) to exposed skin or by applying deet and wearing the treated clothing. Human test subjects were exposed to natural populations of mosquitoes for a 9-hour daytime period (total of 8 days/treatment) while using one or both protection methods. Unprotected test subjects were also exposed for short periods each day as a check to determine the overall biting rate of mosquitoes. The combined use of both protection methods was the most effective treatment in preventing bites, resulting in an average of 1.5 bites/9-hour day, compared with 53.5 and 98.5 bites on subjects protected only with treated clothing or deet, respectively, and 2,287 bites (extrapolated) on subjects who wore untreated clothing during the same time period. Measurements also indicated that the toxic effect of permethrin reduced biting rates by greater than 90% within the immediate area where subjects wore permethrin-treated uniforms for 9 hours.

Animals↗
PubMed1983

Species specificity of streptokinase.

Streptokinase, a bacterial protein, forms a complex with human plasminogen which results in a conformational change in the plasminogen molecule and the exposure of an active center. The plasminogen-streptokinase complex is an activator of plasminogen and is rapidly converted to a plasmin-streptokinase complex which, in the human, is also an activator of plasminogen. Species differences have been found in the reaction of streptokinase with plasminogen varying from no active complex formation at one extreme to the rapid formation of an active activator complex at the other, with resultant differences in rates of complex formation and the yield of plasmin. Explanation of these species differences at a molecular level are discussed as well as the possible application of complex formation in a variety of biological systems as a mechanism to produce variation in enzyme activities in proportion to the concentration of substrate available.

Animals↗
PubMed1983

Insect repellent jacket tests against biting midges (diptera: Culicoides) in Panama.

Light-weight net jackets treated with N,N-diethyl-m-toluamide (deet) were field-tested in Panama against five species of biting midges, principally Culicoides furens (Poey) and C. barbosai Wirth and Blanton. The deet-treated jacket provided 87-93% protection. Time of day as well as season appeared to influence the proportionate numbers of species collected. The mean coefficient of protection was slightly lower during morning tests when C. barbosai was most abundant and higher during evening tests when C. furens was most abundant.

Benzamides↗
PubMed1982

Streptokinase-dependent delayed activation of horse plasminogen.

Complete activation of purified horse plasminogen to plasmin was obtained with a 1:10 molar ratio of streptokinase to plasminogen after 5 min of incubation at 37 degrees C. At a 1:1 molar ratio, maximal activity did not appear until 15-30 min, while at a ratio of 6:1 complete activation was delayed for 120-180 min. Gel filtration studies of isotopically labeled streptokinase and horse plasminogen suggest that the delay was due to impaired formation of a streptokinase-plasminogen complex. The predominant streptokinase moiety within the streptokinase-plasmin complex which forms from the streptokinase-plasminogen complex had a molecular weight of about 25000. The streptokinase-horse plasmin complex activated bovine plasminogen and was relatively stable. Native streptokinase was rapidly modified by horse plasmin predominantly to a fragment with a molecular weight comparable to that of the streptokinase moiety within the horse streptokinase-plasmin complex, about 25000 daltons. Partial characterization of horse plasminogen revealed no striking differences from human plasminogen in terms of molecular weight, N-terminal analysis and amino acid composition. However, horse plasminogen did not react with antibodies to human plasminogen, and its isoenzymes were more acidic than those of the human. Further characterization of horse plasminogen will be required to ascertain whether activation by streptokinase can serve as a model for the altered kinetics which have recently been described for the activation of aberrant types of human plasminogen.

Amino Acids↗
PubMed1982

Evaluation of personal protection methods against phlebotomine sand flies including vectors of leishmaniasis in Panama.

Three personal protection methods were evaluated against phlebotomine sand flies in Panama. Skin applications of five selected repellents including deet (N,N-diethyl-m-toluamide) provided a mean coefficient of protection (CP) of 99.2% against the attack of at least three sand fly species. Deet-treated net jackets also provided good protection, but it was concluded that an additional application of repellent to the unprotected face was necessary for maximum protection. Permethrin-treated clothing did not provide the protection expected. Apparently sand fly behavior and resistance to quick knock-down were responsible for the numbers of bites recorded, and therefore maximum protection from bites would require application of deet or another suitable repellent to the exposed skin when wearing permethrin-treated clothing.

Animals↗
PubMed1979

Nonplasminogen-dependent protease in human plasma.

Equal volumes of plasma and 0.3 M K2HPO4, pH 7.4, were mixed, diluted 20-fold, and adjusted to pH 5.2. After incubation at 37 degrees C for 30 min, the euglobulin percipitate, redissolved in 0.1 M K2HPO4, pH 7.4, developed caseinolytic activity (0.05 CTA U/ml). Na2HPO4 or NaCl of similar ionic strength could replace K2HPO4. The pH optimum of the protease was 6.5, activity falling off sharply below pH 6.0 and above 7.4. The proteolytic activity was inhibited by diisopropylphosphofluoridate and by pancreatic trypsin inhibitor, but was not inhibited by soybean trypsin inhibitor. The activity was not due to plasmin, contact activation, or coagulation factors, since it was fully generated in plasminogen-depleted, factors XII, XI, VII deficient, and prekallikrein-deficient plasmas. Purified Cl-esterase was not caseinolytic in our system. Redissolved euglobulin precipitate prepared from normal plasma without salt addition could serve as starting material for the generation of caseinolytic activity, as could serum, indicating that the Hageman factor cofactor and thrombin are not required. The protease had no detectable procoagulant or fibrinolytic activity.

Chemical Precipitation↗
PubMed1977

Proactivator and activator levels of plasminogen in plasma as measured by caseinolysis.

A procedure is presented for the caseinolytic assay of plasminogen proactivator and activator levels in blood. The validity of the method was established and normal plasma proactivator levels were determined in 10 subjects. No detectible activator activity was found in these subjects. Venous occulsion produced a small rise in activator activity. Hageman-deficient and Fitzgerald trait plasmas did not produce activator activity after exposure to kaolin. The generation of activator activity in the Fitzgerald plasma was partly restored by the addition of purified high molecular weight kininogen, but the Hageman-deficient plasma was not corrected. The caseinolytic assay avoids some of the drawbacks which are inherent in methods which depend on fibrin dissolution for the detection of enhanced fibrinolytic states, provides a reproducible baseline, and may be sufficiently sensitive to detect changes of clinical interest.

Caseins↗
PubMed1977

Factors which influence blood platelet migration.

Migration of human blood platelets in vitro was investigated by a modification of the capillary-tube migration chamber technique used to study the migration inhibition factor of macrophages. Platelets were packed in capillary tubes and incubated in autologous platelet-free plasma (PFP). The extent of migration was quantified by planimetry (measurement of the area of platelet migration visible by stereomicroscopy). Among the various anticoagulants employed, sodium citrate was most suitable for studying platelet migration. Optimal migration occured at 22 degrees to 37 degrees C and pH 7.2 to 7.4. Migration was inhibited by metabolic inhibitors such as iodoacetic acid, sodium fluoride, and 2,4-dinitrophenol, and inhibition was proportional to the dose of the agent added to the incubation medium. Mobility was also inhibited by cytochalasin B, which disrupts cellular microfilaments, at 1 microgram/ml PFP, but not by colchicine, a microtubule inhibitor, even at 40 microgram/ml of PFP. Light and electron microscopy showed that this inhibition was not ascribable to platelet clumping. These observations suggest that platelet mobility is an active process. The possible significance of platelet migration in hemostasis is discussed.

Anticoagulants↗