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Biomedical subjects

R B Davis

Publications and source records attributed to R B Davis.

At least 127 records · Page 7Linked to original sources
PubMed1984

Epornitic of papova-like virus-associated disease in a psittacine nursery.

Of 45 fledgling psittacine birds being raised in an avian nursery, 14 died over a 6-week period. At necropsy, several birds were found to have a moderate amount of subcutaneous hemorrhage over the crop and across the dorsum. Histologically, all birds had hepatic necrosis. Large pale to lightly basophilic intranuclear inclusions were seen in the spleen of 6 birds and in the liver of 5 birds examined. Ultrastructural evaluation demonstrated intranuclear virus particles resembling the papovavirus incriminated as the agent responsible for budgerigar fledgling disease.

Animals↗
PubMed1984

Radiation Therapy Oncology Group Phase I-II study on fast neutron teletherapy for carcinoma of the bladder.

From June 1977 through March 1981, the Radiation Therapy Oncology Group sponsored a Phase I-II study (RTOG 77-05) on the use of fast neutrons for treating carcinomas of the urinary bladder. Patients entered on the study had Stage B1 (grade III or IV histology) or Stage B2, C, or D1 (any grade histology) disease. Thirteen patients received preoperative mixed-beam (neutron/photon) irradiation to 50 photon Gy-equivalent, and in 12 of these a cystectomy was performed in 4 to 6 weeks. The incidence of pathologic downstaging to Po was 58% in the cystectomy specimens. The projected survival at 30 months is 32%. Twenty-six patients were treated definitively with mixed-beam irradiation consisting of 50 photon Gy-equivalent to the pelvis followed by a 20 photon Gy-equivalent boost to the bladder itself. Eighteen of 26 patients (69%) achieved tumor clearance at some time during their follow-up but 8/18 (44%) of these ultimately exhibited some component of local failure. The projected survival at 30 months for this group of patients is 34%. However, the subset of patients with Stage B or C disease had a projected survival at 30 months of 60%. Four patients received definitive neutron irradiation alone and 3/4 achieved tumor clearance at some time during their follow-up. Actuarial curves are presented for patient survival and duration of local control, and results are compared with comparably staged patients treated with megavoltage photon irradiation. Treatment-related morbidity is also discussed.

Aged↗
PubMed1984

Transformation of Fanconi's anemia to acute nonlymphocytic leukemia associated with emergence of monosomy 7.

Two sisters in whom a diagnosis of Fanconi's anemia was made at ages 12 and 18 subsequently developed acute nonlymphocytic leukemia (ANLL). A third sibling had previously died at age 11 of apparent sepsis. Both sisters had cytogenetic studies that showed increased chromosomal breakage and a 46,XX karyotype, but subsequently developed ANLL after, or coincident with, the emergence of monosomy 7. These observations suggest that, in addition to myelodysplastic syndromes and defective neutrophil chemotaxis, monosomy 7 may be associated with the emergence of leukemia in this disorder.

Acute Disease↗
PubMed1983

RTOG Phase I study on fast neutron teletherapy for squamous cell carcinoma of the esophagus.

From August, 1977, through January, 1981, the Radiation Therapy Oncology Group sponsored a Phase I study (RTOG 77-09) on the use of fast neutrons for treating inoperable squamous cell carcinomas of the esophagus. A total of 39 evaluable patients were treated with curative intent using either fast neutrons alone or in combination with low LET irradiation as part of a mixed beam fractionation scheme. Actuarial survival curves are presented for both the "neutrons alone" and the "mixed beam" treatment groups. There was no significant survival difference between these groups of patients. The projected survival at two years is less than 10%, which is comparable with megavoltage photon results for an unselected series of patients. The size of the primary lesion and the initial Karnofsky performance status were found to be the most important prognostic indications for prolonged survival. Sixteen of 39 patients were felt to have achieved local clearance of their tumor at some time during their follow-up with the median time until a local recurrence being 17 months. Treatment related complications and patterns of metastatic spread are discussed. In general, it appeared that the response of large tumors to neutron irradiation resulted in necrosis and fistula formation. In many cases this was accompanied by persistent/recurrent tumor within the high dose radiation volume.

Aged↗
PubMed1983

Thrombocytopenia associated with histoplasmosis and an elevated platelet associated IgG.

A patient with primary pulmonary histoplasmosis, symptomatic thrombocytopenia, and an associated elevation of platelet associated IgG during the acute phase of the illness is described. Whereas thrombocytopenia has been reported previously in patients with disseminated histoplasmosis, it appears that thrombocytopenia in a patient with nondisseminated histoplasmosis has not been described. Although certain clinical findings suggested idiopathic thrombocytopenic purpura, corticosteroids were not administered, and lymph node biopsy documented the presence of Histoplasma capsulatum. Similarly, elevated platelet associated IgG levels apparently have not been reported previously in thrombocytopenic patients with histoplasmosis. Possible mechanisms for thrombocytopenia associated with histoplasmosis are discussed.

Adult↗
PubMed1983

Diagnosis and treatment of pregnancy induced platelet dysfunction.

Pregnant women with either Type B EPH gestosis or gestosis alone were treated with low dose aspirin if thrombocytopenia were present (platelet counts below 75,000) or had platelet aggregation studies if their platelet counts were above 75,000. Platelet aggregation was usually decreased and aspirin therapy appeared to improve platelet counts. However, it appears that platelet abnormalities are only a secondary defect in the "gestosis" process as correction of their thrombocytopenia did not correct their hypovolemia.

Adult↗
PubMed1983

Lincomycin dose response for treatment of necrotic enteritis in broilers.

A dose response study was conducted to determine the appropriate (optimal) lincomycin concentration in drinking water for the treatment of necrotic enteritis (NE) in broilers. The study was replicated twice over time using a total of 2,895 broilers. Birds were raised in a facility containing a built-up litter from a source that experienced NE. They were commingled from 1 day of age until NE was observed. Lincomycin was mixed in drinking water at a rate of 0, .528, 2.114, 8.454, or 33.818 mg/liter for a period of 7 days. The study was terminated 3 weeks after initiation of therapy. Necrotic enteritis was diagnosed by mortality and pathological findings. The data on mortality were analyzed statistically using analysis of variance procedures. The Walker-Carmer technique was applied to estimate the appropriate lincomycin concentration. Lincomycin was effective for the treatment of NE in broilers at concentrations of greater than or equal to 2.114 mg/liter of drinking water. The minimal effective dose that would achieve maximal treatment response (optimal dose) against NE in broilers was estimated to be 16.9 mg lincomycin/liter of drinking water.

Animals↗
PubMed1983

Therapeutic effect of optimal lincomycin concentration in drinking water on necrotic enteritis in broilers.

The efficacy of 16.9 mg lincomycin/liter of drinking water was evaluated for the treatment of necrotic enteritis (NE) in 743 broiler-type chickens. Birds were raised in a facility containing a built-up litter obtained from a source that experienced NE. They were commingled from 1 day of age until NE was observed. Two groups of 6 pens each were given 0 or 16.9 mg lincomycin/liter of drinking water. Water medication was offered fresh daily for 7 days and the study was terminated 3 weeks after initiation of therapy. The susceptibility of Clostridium perfringens to lincomycin was determined in vitro. The test organism was susceptible to lincomycin as reflected by minimal inhibitory concentration and minimal lethal concentration of .156 microgram/ml. Mortality attributed to NE was 0% in lincomycin treated birds and 14% in nonmedicated control birds (P less than .01). Lincomycin water medication was highly effective for the treatment of NE in broilers.

Animals↗
PubMed1982

Effects of soluble fraction of porcine tissue on the aggregation of human blood platelets.

Epistaxis has been controlled by the use of porcine strip packing in patients with thrombocytopenia prior to and with platelet transfusion. The present study has extended previous observations about the probable mode of action of porcine tissue, to show that the addition of an aqueous fraction (AF) of homogenized porcine tissue to platelets causes prompt aggregation in vitro. Human platelet rich plasma was aggregated by the AF using standard turbidimetric techniques. AF acted synergistically with nonaggregating amounts of either adenosine diphosphate or collagen to cause aggregation. Platelet aggregation was enhanced by AF both with 300,000 platelets/cu mm (standard) or with reduced platelet numbers (50,000/cu mm). The results further define possible mechanisms of action of porcine strip packing in patients who have epistaxis and are thrombocytopenic.

Adenosine Diphosphate↗
PubMed1982

The preschool child's response to dental care when accompanied by day-care personnel.

The cooperative behavior of 93 preschool children during first visit to a dentist was studied in order to assess the effect of being accompanied by day-care personnel rather than their parents. Due to external constraints on the study design, there were imbalances with respect to various predictive factors between the groups. Correcting for these imbalances, no difference was found for the children who came with day-care personnel. Age and the ability to communicate verbally with the dentist (i.e., in English) were found to influence behavior significantly.

Child↗
PubMed1981

Effect of gentamicin on heparin activity.

The importance of the effect of gentamicin on heparin activity was investigated. Heparin activity was assessed using the activated partial thromboplastin time (APTT), thrombin clotting time (TCT), and Factor X heparin assay. Drug concentrations used were 0.1, 0.2, 0.3, and 0.4 units/ml heparin with 40, 80, and 400 microgram/ml gentamicin, in vitro in human plasma. The drugs were precipitated at concentrations of 10, 20, 30, and 40 units/ml heparin with 4 and 40 mg/ml gentamicin. After centrifuging, the supernate was diluted to 0.1-0.4 units/ml heparin for assay. There was no change in heparin activity in the presence of gentamicin (in the unprecipitated solutions) as measured by the TCT, Factor X assay, and the APTT; however, APTT was prolonged by gentamicin. In the precipitated samples, heparin activity was lost in the precipitate. No significant clinical interaction that would affect the therapeutic efficacy of heparin was demonstrated except for a pharmaceutical incompatibility between gentamicin and heparin. The APTT, performed with ellagic acid as an activator, is prolonged by gentamicin.

Drug Incompatibility↗
PubMed1980

Platelet dysfunction associated with abdominal aortic aneurysm.

An 82-year-old man with a one-year history of spontaneous ecchymoses and posttraumatic bleeding was found on physical examination to have a pulsatile abdominal mass. Ultrasonography revealed a large abdominal aortic aneurysm with a freely moving 1.5--2-cm intraluminal thrombus. Laboratory data disclosed intravascular hemolysis, disseminated intravascular coagulation, and a prolonged bleeding time. Further investigation of platelet function demonstrated decreased glass bead retention (0-15%), and reduced or delayed aggregation responses to adenosine diphosphate, epinephrine, and collagen. Studies of platelet factor 3 availability, antiplatelet antibodies, and aggregation response to ristocetin were normal. Transfusion of ten units of normal platelets failed to shorten the patient's bleeding time, despite a marked rise in platelet count. Glass bead retention studies on normal and patient blood were not altered by mixture with patient and normal platelet-poor plasma, respectively. Platelet dysfunction in the presence of arterial aneurysm does not appear to have been reported previously.

Aged↗