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Biomedical subjects

D S Davis

Publications and source records attributed to D S Davis.

At least 19 recordsLinked to original sources
PubMed1995

Nuclear actin filaments and their topological changes in frog oocytes.

Previous morphological and biochemical studies have suggested that actin and actin-containing filaments (microfilaments) exist in the eukaryotic nucleus and that they perform important nuclear functions. However, the concept is not widely accepted. In this study, we demonstrate actin and bundles of actin in the nuclei of oocytes of Rana temporaria by immunoblotting and immunogold labeling/electron microscopy. The system and methods used here provided nuclei, free from cytoplasmic contamination. Additionally, we have compared the topological distribution of intranuclear actin filaments in two structurally and functionally distinct stages (stages 3 and 6) of oogenesis. The stage 3 nuclei are extremely active in rRNA transcription and contain multiple nucleoli located at the periphery with the central part occupied by the lampbrush chromosomes. The stage 6 nuclei are transcriptionally inert and contain both nucleoli and chromosomes confined to a small area in the central part. The nuclear lysates derived from the manually isolated stage 3 and 6 nuclei and the nuclear contents obtained by manually removing the nuclear envelope of stage 6 nucleus both contained actin as demonstrated by immunoblotting with an actin-specific monoclonal antibody. When examined by immunogold electron microscopy using the anti-actin antibody, the stage 3 oocyte nuclei showed distinct intranuclear tracks composed of bundles of actin that extended from the nucleoli and chromosomes to the nuclear envelope. The stage 6 oocyte nuclei, on the other hand, showed short stretches of actin bundles in the central part mainly in association with the nucleoli; none of these bundles extended to the nuclear envelope. Taken together, the above results suggest that actin is a structural component of the oocyte nucleus and that polymerized actin undergoes dramatic topological changes correlated with changes in the distribution of nuclear components and their function.

Actins↗
PubMed1995

Enzyme-linked immunoelectrotransfer blot analysis of excretory-secretory proteins of Fascioloides magna and Fasciola hepatica.

Fasciola hepatica is a parasite of cattle (Bos taurus), but not of white-tailed deer (Odocoileus virginianus), while Fascioloides magna is a parasite of white-tailed deer which also infects cattle as dead-end host. Adult parasites were collected from naturally infected white-tailed deer or cattle. Excretory-secretory proteins (ESP) were obtained from each parasite. Protein banding patterns were analysed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and probed using sera from experimentally infected deer of cattle using enzyme-linked immunoelectrotransfer blot (EITB, also known as Western blot) analysis. Protein banding patterns of the two species were different. EITB analysis of Fascioloides magna ESP using sera from Fascioloides magna infected deer or cattle identified three bands of approximately 17, 22 and 27 kDa of which the 27 kDa antigen cross-reacted with sera from Fasciola hepatica infected cattle. EITB analysis of Fasciola hepatica ESP probed with sera from Fasciola hepatica infected cattle identified three bands of approximately 15, 26 and 46 kDa. The 46 and 26 kDa ESP cross-reacted with sera from Fascioloides magna infected cattle, but not with sera from Fascioloides magna infected deer. The band at 15 kDa which reacted specifically for Fasciola hepatica infected cattle sera consisted of two protein bands close to each other as seen on the SDS-PAGE gel. The EITB reaction at approximately 17 kDa and 22 kDa of Fascioloides magna ESP, and at approximately 15 kDa of Fasciola hepatica ESP can be used for species specific diagnosis.

Animals↗
PubMed1994

Use of bait containing triclabendazole to treat Fascioloides magna infections in free ranging white-tailed deer.

Triclabendazole-medicated corn bait was given to white-tailed deer (Odocoileus virginianus) on the Welder Wildlife Refuge, Sinton, Texas (USA), at a dose of 11 mg/kg body weight per deer per day for seven days, for control of Fascioloides magna. Medicated bait was offered for one week each during the winters of 1987, 1988, and 1989. Deer collected from treated areas, from baited control and from unbaited control areas were examined before the start of the study in 1987, and four weeks after the end of the baiting period in each of three years. Prior to the study, prevalence of fluke infection was 68%. After treatment with triclabendazole medicated corn, 13 (56%) of 23 deer collected were infected with flukes of which 15% had live parasites; this was evidence for therapeutic treatment. Of the deer collected in the baited and unbaited control areas, 63% and 80%, respectively, were infected only with live flukes. Prevalence of live flukes in deer was significantly (P < 0.05) lower in the treatment pasture than in the baited or unbaited control areas in each of the three years. Efficacy of the baiting system over the three years was 63% when comparing the treatment area and the baited control area.

Animals↗
PubMed1993

An enzyme-linked immunosorbent assay for detecting anthrax antibody in white-tailed deer (Odocoileus virginianus): evaluation of anthrax vaccination and sera from free-ranging deer.

An enzyme-linked immunosorbent assay for anthrax antibody in white-tailed deer (Odocoileus virginianus) was developed and used to evaluate a vaccination study and compare sera from hunter-killed deer in anthrax endemic and non-endemic areas. Deer subcutaneously vaccinated with anthrax avirulent spore vaccine developed specific antibody to protective antigen (PA) which was significantly higher than the non-vaccinated controls at 30, 60, 90, and 240 days post-vaccination. There was no difference between the levels of antibody to PA between deer in anthrax endemic and non-endemic areas.

Animals↗
PubMed1993

Those who don't give.

Explore the source record for details and available documents.

Emigration and Immigration↗
PubMed1992

Organ transplants, foreign nationals, and the free rider problem.

There is strong sentiment for a policy which would exclude foreigners from access to organs from American cadaver donors. One common argument is that foreigners are 'free riders'; since they are not members of the community which gives organs, it would be unfair to allow them to receive such a scare resource. This essay examines the philosophical basis for the free rider argument, and compares that with the empirical data about organ donation in the U.S. The free rider argument ought not to be used to exclude foreign nationals because it is based on fallacious assumptions about group membership, and how the 'giving community' is defined. Polls show that even among the seventy-five per cent of Americans who support organ donation, only seventeen per cent had taken the small step of filling out donor cards. Therefore, it goes against logic to define the giving community as coextensive with American residency, while excluding foreigners who might well have become donors had they lived in countries which provided that option.

Emigration and Immigration↗
PubMed1991

Comparison of results from five serologic methods used for detecting Brucella abortus antibody activity in coyote sera.

A total of 423 serum samples representing 94 coyotes which were wild trapped in east Texas were used to compare the serologic results from five different methods for detecting antibodies to Brucella abortus. The sera were tested for Brucella spp. antibody activity by the Card (CARD), rivanol precipitation (RIV), standard agglutination tube (SAT), cold complement fixation test (CF), and enzyme linked immunosorbent assay (ELISA) methods. Each serum sample selected for this comparison demonstrated antibody activity by one or more of the five serologic methods. When the serologic results of the five different methods were compared, 143 sera were positive according to the CF test and agreement was 67.1-70.6% with CARD, RIV and SAT. The maximum agreement for CF positive was with CARD (70.6%) and the lowest agreement fro CF negative was also with CARD (56.4%). Agreement among the serologic methods for the SAT positive ranged from 69.1% (CARD) to 72.7% (RIV). Agreement between SAT and ELISA was poor with only 38.1% agreement for SAT positive and 11.3% agreement for SAT negative. Agreement between methods for CARD positive sera was poor, with a low of 43% for both SAT and ELISA, and a high of 55.6% for RIV. Agreement between methods for 149 RIV positive sera was 83.2% for CARD, 67.8% for SAT, 64.4% for CF and only 50.3% for ELISA. Agreement between methods for ELISA positive results ranged from 49.0% for RIV to 62.7% for CARD.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Diseases↗
PubMed1991

Brucella abortus in Bison. II. Evaluation of strain 19 vaccination of pregnant cows.

Protection against Brucella abortus induced abortion and infection provided by strain 19 (S19) vaccination was evaluated in American bison (Bison bison). Forty-eight pregnant bison were manually inoculated (MI) with S19 vaccine, 44 were ballistically inoculated (BI) with an absorbable hollow pellet containing lyophilized S19, and 46 were manually injected with buffered saline as non-vaccinated controls (NVC). All bison were Brucella spp. seronegative prior to the experiment, in the second trimester of pregnancy, and were randomly assigned to experimental groups. Approximately 60 days post-vaccination, abortions were observed in the vaccinated bison. Brucella abortus strain 19 was recovered from a bison that had recently aborted, her fetus, and from 11 of 12 other aborted fetuses. Fifty-eight percent (53 of 92) of vaccinated bison aborted, and no abortions were observed in the NVC bison. One cow aborted during her second post-vaccinal pregnancy and S19 was identified from the dam and fetus indicating that chronic S19 infections can occur in bison. Positive antibody titers were present 10 mo post-vaccination in 73% (66 of 91) of the bison. Thirteen mo post-vaccination, 30 MI vaccinates, 27 BI vaccinates, and 30 NVC bison were challenged during the second trimester of pregnancy with 1 x 10(7) CFU of B. abortus strain 2308 via bilateral conjunctival inoculation. Protection against abortion was 67% (P less than or equal to 0.0001) for vaccinated bison compared to 4% in NVC. Protection against B. abortus infection was determined to be 39% (P greater than or equal to 0.001) for vaccinates and 0% (zero of 30) for NCV. Persistent antibody titers, vaccine induced abortions, and chronic S19 infections indicate that the S19 vaccine doses used in this study are not suitable for pregnant bison.

Abortion, Veterinary↗
PubMed1990

Effect of psychiatric liaison nurse specialist consultation on the care of medical-surgical patients with sitters.

One hundred seven patients in an acute care setting who had lay sitters to provide the constant observation judged necessary to meet their safety needs were studied to determine the effect of psychiatric liaison nurse specialist (PLNS) consultation on nursing care and the use of sitters. After placement in either a suicidal or nonsuicidal group, subjects were randomly assigned to receive consultation or not. Outcome variables of number of sitter shifts, number of nursing note observations, number of patient and sitter incidents and length of hospital stay were considered. Multiple analysis of variance indicated no significant differences among the groups for number of sitter shifts or number of nursing note observations. A significant main effect for group on length of hospital stay was found with suicidal patients having a significantly shorter hospital stay. Number of patients and sitter incidents were too small for analysis.

Adult↗
PubMed1990

Localization of adenovirus-encoded DNA replication proteins in the nucleus by immunogold electron microscopy.

The distribution of three adenovirus-encoded DNA replication proteins in the nucleus of human 293 cells was studied by immunogold electron microscopy. The infected nuclei contained four morphologically distinct inclusions. They were highly electron-dense granules (type I), compact fibrogranular masses of medium electron density (type II), filamentous masses of low electron density (type III) and large polygonal crystals (type IV). In immunogold labelling studies, antibodies to the adenovirus single-stranded DNA-binding protein (DBP) and antibodies to single-stranded DNA showed extensive binding to the type III inclusions. The antibodies to the adenovirus DNA polymerase (AdPol) and terminal protein (TP) predominantly labelled type II inclusions. Double immunogold labelling studies detected low levels of AdPol and TP in type III inclusions and DBP in type II inclusions. The selective distribution of DNA replication proteins suggests that the type II and III inclusions represent two functionally different entities that may be involved in two different aspects of adenovirus DNA replication, i.e. chain initiation and elongation.

Adenoviridae↗
PubMed1990

Use of albendazole in feed to control Fascioloides magna infections in captive white-tailed deer (Odocoileus virginianus).

Thirty-six adult white-tailed deer (Odocoileus virginianus) naturally infected with Fascioloides magna were captured and randomly assigned to four groups. Each group was fed pelleted feed coated with albendazole for each of seven consecutive days to deliver the drug at a dose rate of approximately 0.0, 5.0, 8.5, or 16.5 mg/kg bodyweight/day. At 7 wk posttreatment, each animal was euthanized and necropsied. Effects of albendazole treatment included significant reduction (P less than 0.05) in parasite egg count per gram of feces and increase in serum albumin concentration (P less than 0.05). Smaller parasites or remains of dead parasites were seen at the end of migratory tracks in the treated groups. Efficacy of the drug was 82 to 84%.

Administration, Oral↗
PubMed1990

Brucella abortus in captive bison. I. Serology, bacteriology, pathogenesis, and transmission to cattle.

Two groups of six, non-brucellosis vaccinated, brucellosis seronegative pregnant American bison (Bison bison) were individually challenged with 1 x 10(7) colony forming units (CFU) of Brucella abortus strain 2308. Three days after challenge, each bison group was placed in a common paddock with six non-vaccinated, brucellosis susceptible, pregnant domestic heifers. In a parallel study, two groups of six susceptible, pregnant cattle were simultaneously challenged with the identical dose as the bison and each group was placed with six susceptible cattle in order to compare bison to cattle transmission to that observed in cattle to cattle transmission. Blood samples were collected from bison and cattle weekly for at least 1 mo prior to exposure to B. abortus and for 180 days post-exposure (PE). Sera from the bison and cattle were evaluated by the Card, rivanol precipitation, standard plate agglutination, standard tube agglutination, cold complement fixation tube, warm complement fixation tube, buffered acidified plate antigen, rapid screening, bovine conjugated enzyme linked immunosorbent assay, bison or bovine conjugated enzyme linked immunosorbent assay, and the hemolysis-in-gel techniques for the presence of antibodies to Brucella spp. At the termination of pregnancy by abortion or birth of a live-calf, quarter milk samples, vaginal swabs, and placenta were collected from the dam. Rectal swabs were collected from live calves, and mediastinal lymph nodes, abomasal contents and lung were taken at necropsy from aborted fetuses for culture of Brucella spp. These tissues and swabs were cultured on restrictive media for the isolation and identification of Brucella spp. Pathogenesis of brucellosis in bison was studied in an additional group of six pregnant bison which were challenged with 1 x 10(7) CFU of B. abortus strain 2308. One animal was euthanatized each week PE. Tissues were collected at necropsy and later examined bacteriologically and histologically. Lesions of brucellosis in bison did not significantly differ grossly or histologically from those in cattle. There were six abortions and two nonviable calves in the bison group, as compared to nine abortions in the 12 similarly inoculated cattle. As determined by bacterial isolations, transmission of B. abortus from bison to cattle (five of 12 susceptible cattle became infected) did not differ statistically from cattle to cattle transmission (six of 12 susceptible cattle became infected) under identical conditions. No single serologic test was constantly reliable to diagnosing B. abortus infected bison for 8 wk PE.(ABSTRACT TRUNCATED AT 400 WORDS)

Agglutination Tests↗
PubMed1989

Serological prevalence and isolation of Babesia odocoilei among white-tailed deer (Odocoileus virginianus) in Texas and Oklahoma.

Serum samples collected from 581 white-tailed deer (Odocoileus virginianus) from Texas and from 124 white-tailed deer from Oklahoma were tested by the indirect fluorescent antibody technique against Babesia odocoilei. Prevalence of seropositive reactors varied from site to site in both states. Prevalence rates were statistically ranked as high, intermediate or low. Deer less than 12-mo-old had a significantly lower prevalence than all other age classes.

Age Factors↗
PubMed1989

Efficacy of triclabendazole against fascioloidiasis (Fascioloides magna) in naturally infected white-tailed deer (Odocoileus virginianus).

The efficacy of triclabendazole was evaluated in the treatment of naturally acquired Fascioloides magna infections in white-tailed deer (Odocoileus virginianus). Twenty white-tailed deer were captured on the Welder Wildlife Refuge (Sinton, San Patricio County, Texas, USA) and maintained in a 64 x 64 m deer enclosure. Ten deer were given a 5% suspension of triclabendazole orally at a dosage of 10 mg/kg body weight and 10 deer were given a placebo. Three wk later the deer were euthanized and examined for parasites. At necropsy 19 deer were infected. All specimens of F. magna from the tissues of the triclabendazole treated deer were dead or severely affected by the drug as indicated by changes in their size, color, movement and texture relative to those from control deer. The drug was considered 100% effective against this parasite. Adverse reactions of the deer to the drug were not observed.

Animals↗