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Biomedical subjects

K S Todd

Publications and source records attributed to K S Todd.

At least 37 records · Page 2Linked to original sources
PubMed1986

The sporulation time of Isospora suis oocysts from different sources.

Feces containing Isospora suis oocysts were collected from naturally- and experimentally-infected pigs from four different areas of the United States. The unsporulated oocysts were cleaned, concentrated, mixed with 2.5% aqueous potassium dichromate solution, poured into petri dishes to a depth of 5 mm, and incubated at 25 degrees C. The oocysts were examined with a microscope at 12 h intervals and the stages of sporulation present were counted. Although a few oocysts were completely sporulated after 12 h of incubation, in most fecal samples the majority of the oocysts were not completely sporulated until 24 or 36 h. In the present study, the sporulation time of I. suis oocysts was considered to be less than or equal to 48 h. There were no major differences in the sporulation times of I. suis oocysts from the different sources.

Animals↗
PubMed1986

Anti-strongyle activity of a propylene glycol-glycerol formal formulation of ivermectin in horses (mares).

Four groups of 10 horses (mares) each were treated with a 1% solution of ivermectin (200 micrograms/kg of body weight) in a propylene glycol-glycerol formal base orally, a 1% solution of ivermectin (200 micrograms/kg) in a propylene glycol-glycerol formal base via nasogastric tube, a 1.87% paste of ivermectin (200 micrograms/kg) orally, or a 22.7% paste of oxibendazole (10 mg/kg) orally. Fecal examinations were done before treatment and on posttreatment days (PTD) 14, 28, 42, 56, and 70. Strongyle egg per gram counts and sugar flotation fecal examinations were performed. Results of fecal examinations before treatment were similar in all horses. All horses treated with ivermectin had similar percentages of reductions in mean strongyle egg per gram counts after treatment; 100% on PTD 14, 28, and 56 and 93.4% to 98.7% on PTD 70. All ivermectin treatment groups had 0 horses detected as passing strongyle eggs on PTD 14 and 28, 0 to 2 on PTD 42, 3 to 5 on PTD 56, and 8 to 9 on PTD 70. Horses treated with oxibendazole had 99.9%, 99.7%, 92.9% 78.6%, and 54.5% reductions in mean strongyle egg per gram counts and 5, 7, 8, 9, and 9 horses detected as passing strongyle eggs on PTD 14, 28, 42, 56, and 70, respectively. Adverse reactions to treatment were not observed.

Animals↗
PubMed1986

Efficacy of ivermectin against Dirofilaria immitis larvae in dogs 30 and 45 days after induced infection.

Forty-two Beagles, 14 to 15 weeks of age, were injected subcutaneously with 50 infective larvae of Dirofilaria immitis and were allotted by weight, within sex, to 6 treatment groups. Group 1 served as nonmedicated vehicle-treated controls; groups 2 through 5 were given an oral tablet form of ivermectin at dosages of 0.3 micrograms/kg, 1.0 micrograms/kg, 2.0 micrograms/kg, and 3.3 micrograms/kg at 30 days after inoculation; group 6 was given the 2.0 micrograms/kg dosage at 45 days after inoculation. Dogs were euthanatized and necropsied 154 days after treatment (day 139 for dogs in group 6) and examined for heartworms. On the numerical bases of helminths recovered in the groups, the efficacies for preventing heartworm maturation were 0% (group 2), 53.2% (group 3), 97.2% (group 4), 98.1% (group 5), and 63.8% (group 6). Drug-related adverse reactions were not detected.

Animals↗
PubMed1985

Evaluation of febantel used concurrently with piperazine citrate in horses.

Fifty horses from a herd known to have benzimidazole-resistant small strongyles were treated with febantel (6 mg/kg), combinations of febantel (6 mg/kg) and piperazine citrate (25 or 55 mg base/kg), thiabendazole (44 mg/kg), or placebo (0.6 ml of water/kg). Pretreatment and 7-day posttreatment fecal examinations were done. Fecal cultures, strongyle egg per gram (epg) counts, sugar flotation fecal examinations, and in vitro testing for benzimidazole resistance were performed. Results of fecal examinations before treatment were similar in all horses, and results of testing were positive for benzimidazole resistance. Horses treated with febantel and piperazine at all dosages had significantly lower mean strongyle epg counts and greater percentage reduction in mean strongyle epg counts (99.7% to 99.9%) 7 days after treatment, compared with those determined for horses treated with febantel, thiabendazole, or placebo. Adverse reactions to treatment were not observed.

Animals↗
PubMed1985

Anthelmintic activity of ivermectin against immature gastrointestinal nematodes of sheep.

Twenty-four lambs of mixed breeding with mixed experimental infections of Haemonchus contortus, Ostertagia circumcincta, Trichostrongylus axei, and T colubriformis were allotted to 4 groups. One group (control) was given the vehicle propylene glycol, and the others were given 100, 200, or 300 micrograms of ivermectin/kg of body weight by mouth. Twelve days after treatment, the sheep were necropsied. The compound was greater than 99% effective against immature stages of 4 nematode species at all dosages, except at the 100 micrograms/kg dosage, where efficacy was 96% against H contortus.

Animals↗
PubMed1984

Effects of marginally negative energy balance on insulin binding to erythrocytes of normal men.

Six healthy male volunteers were confined to a metabolic unit for 105 days. Energy intake (EI) and energy expenditure (EE) were varied in order to achieve either a marginally negative (-15%) or an equilibrated energy balance (EB), in different metabolic periods (MP) as follows: MP I: EE = 1, EI = 1, EB = 0; MP II: EE = 1, EI = 0.85, EB = -15%; MP III: EE = 0.85, EI = 0.85, EB = 0; MP IV: EE = 0.85, EI = 0.70, EB = -15%; MP VI: EE = 1.15, EI = 1.15, EB = 0; MP VII: EE = 1.15, EI = 1, EB = -15%. An egg protein formula diet was fed throughout the study. The amount given in MP I was sufficient to maintain body weight constant. Assigned physical activity consisted of regulated walking and cycling. During MP I, this physical activity accounted for 15% of the energy intake. Serum insulin, insulin binding to erythrocytes and body fat content were determined at the end of each MP. No significant changes were found in serum insulin level throughout the study, but specific insulin binding did change significantly. Binding increased with increased physical activity by 23% at the end of MP VI and an additional 35% at the end of MP VII. The maximum percentage of insulin binding to erythrocytes correlated inversely with the percentage of body fat in each MP. These data suggest that insulin binding to erythrocytes, in normal men, is sensitive to a small change in energy balance, and especially to physical activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Hormonal changes in normal men under marginally negative energy balance.

Six men were confined to a metabolic unit for 105 days. Their assigned work and energy intake were varied throughout six metabolic periods in order to create either a marginally negative (-15%) or an equilibrated energy balance. They were fed a defined diet providing a constant amount of protein. At each metabolic period, T4, T3, reverse T3(rT3), free T3, free reverse T3, thyroid-stimulating hormone, cortisol, cortisol-binding globulin, testosterone, and testosterone/estradiol-binding globulin were measured. Free urinary cortisol was measured daily. Results show that serum thyroid hormones are sensitive to marginal changes in energy intake, expenditure, and balance. The ratio T4/T3 appears to be more sensitive to the balance itself, with the ratio T3/rT3 being more sensitive to the intake and expenditure level at which this balance is established. Regulations of T3 and rT3 production are probably distinct. Urinary cortisol did not show any variation that could be related to the energy balance. However, daily urinary cortisol was correlated to daily urinary nitrogen excretion. No change in serum testosterone was found.

Adult↗
PubMed1984

Nitrogen balance in men with adequate and deficient energy intake at three levels of work.

Two studies were conducted to investigate the effects of mild exercise on nitrogen balance in men given diets supplying adequate or slightly limiting energy. In experiment A the diet supplied 91 mg N/kg body weight (0.57 g protein/kg, the FAO/WHO safe level of intake) as egg white; in experiment B the same source was used to provide the 1980 NRC-RDA for adult males, 128 mg N/kg body weight (0.8 g protein/kg). By adjusting energy intake and activity, periods of energy equilibrium and negative energy balance (-15%) were achieved at three levels of activity (X for exercise): no programmed work (0.85X), 1 hour of treadmill walking (1.0X) and 1 hour each of treadmill and cycle ergometry (1.15X). "True" nitrogen balance (TNbal) was more positive or less negative during periods of energy equilibrium as compared to those of energy deficit. This effect of energy balance on TNbal increased with physical activity. At the lower protein intake the mean difference in TNbal between the period of energy equilibrium and that of energy deficit at 1.0X was 0.19 g N/day (nonsignificant difference) and 0.54 g N/day at 1.15X. When protein intake was increased, the difference in TNbal between periods of equilibrium and deficit was significant at all levels of activity: 0.65 g N/day at 0.85X, 0.93 g N/day at 1.0X and 1.09 g N/day at 1.15X. Physical activity was anabolic when energy balance was maintained. In experiment A the addition of 1 hour of exercise (1.0X to 1.15X) spared 2.5 mg N/kg body weight; reducing activity by 1 hour (1.0X to 0.85X) cost 1.4 mg N/kg body weight. In experiment B, TNbal was more positive with increased activity (by 5.9 mg N/kg body weight) and more negative (by 11.5 mg N/kg body weight) when the men were sedentary. During periods of energy deficit, the anabolic effect of activity was also present, although less markedly. When activity increased from 1 to 2 hours in experiment A, TNbal improved by 2.1 mg N/kg body weight and in experiment B, by 3.5 mg N/kg body weight. Thus, circumstances of negative energy balance with adequate protein intake are better tolerated when the energy deficit is generated by physical activity than when it derives from reduced intake; the picture when protein intake is marginal requires further investigation.

Adult↗
PubMed1984

Transmission electron microscopy of meront development of Eimeria vermiformis Ernst, Chobotar and Hammond, 1971 (Apicomplexa, Eucoccidiorida) in the mouse, Mus musculus.

First and second generation meronts of Eimeria vermiformis developed in epithelial cells of the crypts of Lieberkühn. They were usually between the host cell nucleus and the basement membrane. Sporozoite organelles dedifferentiated with the first generation meront's development except for the refractile body and the apical complex, which persisted. After several nuclear divisions, the apical complex dedifferentiated further until only micronemes remained attached by a duct system to the plasmalemma. The form of the apical complex was highly variable. Sometimes the duct system was absent and the micronemes were attached directly to the plasmalemma or a dense material on it. Crescent body-like material was often present in the parasitophorous vacuole next to the microneme structure. The microneme structure was not present in second generation meronts but evaginations of the plasmalemma, cytoplasmic outpocketings, and cytoplasmic vesicles were associated with the round granular bodies in the parasitophorous vacuoles. During first generation merogenesis, invaginations from the parasitophorous vacuole formed channels into the meront along which merozoites budded. Micropores were often at the ends of these invaginations. These and other micropores of the meront had a dense U-shaped band for a collar while those of the merozoites had a collar with a double band of dense material that connected to the inner membrane. First generation merozoites budded randomly from the meront, resulting in a residual body that was usually in the middle of the parasitophorous vacuole. Second generation merozoites budded in one direction, resulting in a peripheral residual body and merozoites that were parallel in an oblong parasitophorous vacuole.

Animals↗
PubMed1984

Pathological changes and immunity associated with experimental Eimeria vermiformis infections in Mus musculus.

Pathological changes and immunity induced by Eimeria vermiformis (Ernst, Chobotar & Hammond, 1971) were studied in outbred Swiss mice inoculated with 5000, 10,000, 20,000, or 40,000 oocysts. Cross immunity to E. ferrisi was also studied. In the case of E. vermiformis, mortality was dose dependent; most deaths were observed in the intermediate-dose groups. Most deaths also correlated with peak oocyst output. Histopathologic changes consisted of an early neutrophil and mononuclear cell infiltration in the small intestine. Later, villus atrophy and crypt hyperplasia caused a decrease in the villus-crypt ratio. During the acute phase (8-10 days after inoculation), villus tips were eroded and parasites with necrotic debris filled the cryptal and intestinal lumina. Vacuolar changes were observed in epithelial cells of the small intestine. Neither parasites nor significant pathological changes were observed in extra-intestinal organs. Mice were totally immune to reinfection with E. vermiformis 30 and 105 days after inoculation. Cross immunity was not observed between E. vermiformis and E. ferrisi.

Animals↗
PubMed1984

Diagnostic criteria for an enzyme-linked immunosorbent assay for occult heartworm disease: standardization of the test system in naturally exposed dogs.

The development of criteria for interpreting and reporting the results of an occult heartworm enzyme-linked immunosorbent assay to practitioners is described. The antigen is a saline extract of adult female Dirofilaria immitis. The cutoff absorbance A400 nm values were estimated, using 106 dogs free of infection. Any A400 nm value less than 0.526 is considered negative and values greater than or equal to 0.784 are positive. Intermediate A400 nm values are interpreted as suspect. Absorbance values for serum samples from 13 client-owned amicrofilaremic dogs revealed a bimodal distribution consistent with presumptive diagnosis based on clinical signs, which indicates that the test may be used to support a diagnosis of occult heartworm disease. The present serotest, however, is unable to distinguish microfilaremic dogs from noninfected dogs. Serum from dogs infected with other common helminths failed to crossreact with the D immitis antigen, with the exception of Dipetalonema reconditum.

Animals↗
PubMed1984

Anthelmintic efficacy of avermectin B1a and dihydroavermectin B1a against ovine gastrointestinal nematodes in 1977.

In a critical study, 40 female mixed-breed lambs with experimental infections of Cooperia spp, Trichostrongylus colubriformis, Ostertagia circumcincta, T axei, and Haemonchus contortus were allocated to 8 groups in 1977. Groups 1 and 5 served as controls. Groups 2 to 4 were treated orally with avermectin B1a at dosage levels of 25, 50, and 100 micrograms/kg of body weight, respectively. Groups 6 to 8 were given oral dihydroavermectin B1a at dosage levels of 50, 100, and 200 micrograms/kg, respectively. The lambs were euthanatized and necropsied 6 days after treatment. The compounds were greater than 99% effective at all dosage levels.

Animals↗
PubMed1984

Ivermectin and an ivermectin-penicillin combination: a comparison of anthelmintic efficacy in horses.

Ivermectin given IM at 200 micrograms/kg, alone or in combination with procaine penicillin G at 600 IU/kg, to 20 randomly selected young horses of various breeds reduced fecal strongyle egg counts from 400-4100 epg (avg greater than 1000) pretreatment to zero 7 days posttreatment. There were no systemic or injection-site reactions, either immediate or delayed, in any of the horses.

Animals↗
PubMed1983

Evaluation of mebendazole used concurrently with piperazine monohydrochloride in horses.

Forty horses from a herd known to have benzimidazole-resistant small strongyles were treated with mebendazole (8.8 mg/kg) or combinations of mebendazole and piperazine monohydrochloride (25, 40, or 55 mg of piperazine base/kg). Pretreatment and 7-day posttreatment fecal examinations were done. Fecal cultures and strongyle egg per gram (epg) counts, and in vitro testing for benzimidazole resistance were performed. Results of fecal examinations prior to treatment were similar in all horses, and results of testing were positive for benzimidazole resistance. Horses treated with mebendazole and piperazine at all dosages had much lower geometric mean strongyle epg counts (2 to 4) and greater percentage reduction in geometric mean strongyle epg counts (99.7 to 99.9) at 7 days after treatment, compared with those measurements for horses treated with mebendazole alone. Adverse reactions to treatment were not observed.

Animals↗
PubMed1983

Food intake measurement: problems and approaches.

Sources of variance in dietary intake records were measured and compared. Eighteen graduate students recorded self-selected food intakes during a 30-day study. Subjects were divided into two groups and on alternating 5 consecutive day periods, one group weighted all food consumed and recorded it on tape recorders while the other group recorded estimated intake in small notebooks. An average of two, 24-h dietary recalls was also obtained from each subject and compared to previously estimated intake. The major contributions to total variance were within subject and between subject variance. There was no difference in the mean protein and energy intake recorded by weighing when compared to that recorded in household measures, but there was less variability in the records obtained by weighting intake. The 95% confidence limits were calculated both for the group's and an individual's intake for each method, these demonstrated that 1-day dietary record gave a reasonable estimate (within 15%) of the usual intake of the group. However, the 1-day record, regardless of which method used, gave a meaningless estimate of an individual's usual diet. The protein/energy ratios and the coefficient of interindividual variation are also reported.

Adult↗