PubMed Health⌕ Search

Biomedical subjects

K E Russell

Publications and source records attributed to K E Russell.

16 recordsLinked to original sources
PubMed2001

Intratracheal administration of recombinant human factor IX (BeneFix) achieves therapeutic levels in hemophilia B dogs.

The purpose of this paper was to establish proof of concept for administration of human recombinant F.IX (rF.IX) by inhalation for therapy of hemophilia B. The pharmacokinetics of intratracheal (IT) administration of rF.IX was studied in nine hemophilia B dogs randomized into 3 groups that received 200 IU/kg IT, 1,000 IU/kg IT, or 200 IU/kg intravenously (IV). IT rF.IX produced therapeutic levels of F.IX antigen and activity and the pharmacokinetic parameters were consistent with a slow release from a depot site within the lungs. Bioavailability compared to IV administration was 11% for 200 IU/kg IT and 4.9% for 1,000 IU/kg. The whole blood clotting time began to shorten at 2 h but F.IX bioactivity was not detected until 8 h post infusion in both IT groups. In all groups, F.IX activity was detected through 72 h post administration. These data demonstrate that biologically active rF.IX can reach the systemic circulation when given IT. Aerosolization of rF.IX may provide a needle-free therapeutic option for delivery of rF.IX to hemophilia B patients.

Administration, Inhalation↗
PubMed2000

Intracellular function in rehydrated lyophilized platelets.

This study aimed to evaluate the effect of cross-linking and lyophilization on intracellular signalling processes in rehydrated, lyophilized (RL) platelets, which are under development as a platelet substitute for transfusion. Exposure of RL platelets to thrombin resulted in enhanced phosphorylation of several proteins, including 18 kDa and 42 kDa kinase substrates that were shown to be the substrates of myosin light chain and protein kinase C respectively. Cross-linking and lyophilization depleted the platelets of free cytoplasmic ADP and ATP, but had less effect on protein-bound nucleotides. The surface membrane of RL platelets was found to be permeable to poly dT probes less than approximately 3 kDa in size; larger nucleotide probes and proteins did not penetrate the surface membrane. Taken together, our results indicate that RL platelets retain some of the haemostatic stimulus-response functions of fresh platelets and are capable of feedback amplification in coagulation.

Adenosine Diphosphate↗
PubMed1999

Platelets from thrombocytopenic ponies acutely infected with equine infectious anemia virus are activated in vivo and hypofunctional.

Thrombocytopenia is a consistent finding and one of the earliest hematological abnormalities in horses acutely infected with equine infectious anemia virus (EIAV), a lentivirus closely related to human immunodeficiency virus. Multifactorial mechanisms, including immune-mediated platelet destruction and impaired platelet production, are implicated in the pathogenesis of EIAV-associated thrombocytopenia. This study was undertaken to investigate whether regenerative thrombopoiesis and platelet destruction occurred in ponies acutely infected with EIAV. Circulating large, immature platelets were increased in ponies acutely infected with EIAV late in the infection when platelet count was at a nadir. Morphometric analysis of bone marrow from acutely infected ponies revealed significant increased in megakaryocyte area and megakaryocyte nuclear area. A trend toward increased numbers of megakaryocytes was also observed. Platelets from acutely infected ponies had increased surface-bound fibrinogen and ultrastructural changes consistent with in vivo platelet activation. Platelets also had hypofunctional aggregation responses to three agonists in vitro. We conclude that thrombocytopenia in ponies acutely infected with EIAV is regenerative and suggest that bone marrow platelet production is not severely compromised in these ponies. Our findings reveal that in vivo platelet activation occurs in ponies acutely infected with EIAV, and as a result platelets are hypofunctional in vitro. Activation of platelets in vivo may cause platelet degranulation or formation of platelet aggregates, which would result in removal of these damages platelets from circulation. This may represent a form of nonimmune-mediated platelet destruction in ponies acutely infected with EIAV.

Animals↗
PubMed1999

Increased interleukin-6 activity in the serum of ponies acutely infected with equine infectious anaemia virus.

Seven ponies were infected with the virulent wild-type Wyoming strain of equine infectious anaemia virus (EIAV). Infection status was monitored by serum reverse transcriptase activity, rectal temperature, and complete blood count. Preinfection serum and serum obtained during the initial febrile episode following infection were assayed for interleukin 6 (IL-6) activity. Postinfection IL-6 activity was significantly increased as compared to preinfection values. The magnitude of increase in IL-6 was positively correlated with reverse transcriptase activity (an indirect measure of viraemia) but was not correlated with rectal temperature. IL-6 production in response to EIAV infection may play a role in pathogenesis of disease, especially the hyperglobulinaemia and apparent polyclonal B cell activation in these horses.

Animals↗
PubMed1998

A strategy for dose-finding and safety monitoring based on efficacy and adverse outcomes in phase I/II clinical trials.

We propose a design strategy for single-arm clinical trials in which the goals are to find a dose of an experimental treatment satisfying both safety and efficacy requirements, treat a sufficiently large number of patients to estimate the rates of these events at the selected dose with a given reliability, and stop the trial early if it is likely that no dose is both safe and efficacious. Patient outcome is characterized by a trinary ordinal variable accounting for both efficacy and toxicity. Like Thall, Simon, and Estey (1995, Statistics in Medicine 14, 357-379), we use Bayesian criteria to generate decision rules while relying on frequentist criteria obtained via simulation to determine a design parameterization with good operating characteristics. The strategy is illustrated by application to a bone marrow transplantation trial for hematologic malignancies and a trial of a biologic agent for malignant melanoma.

Bayes Theorem↗
PubMed1998

Hyperglobulinemia and lymphocyte subset changes in naturally infected, inapparent carriers of equine infectious anemia virus.

OBJECTIVE: To determine blood protein concentration, immunoglobulin concentration, and lymphocyte profiles in equine infectious anemia virus (EIAV) seropositive, naturally infected horses without clinical signs of disease. ANIMALS: 26 clinically normal seropositive horses, 6 febrile ponies with experimentally induced EIA, and 52 clinically normal seronegative horses and ponies. PROCEDURE: Serum and EDTA-anticoagulated blood were obtained from all horses and ponies, and total serum protein and albumin concentrations, immunoglobulin concentrations, and blood lymphocyte subset counts were determined. RESULTS: Compared with seronegative horses, EIAV seropositive inapparent carrier horses had no significant difference in serum reverse transcriptase activity, PCV, or platelet count. Inapparent carrier horses had increased plasma total solids and serum globulin concentrations and decreased serum albumin concentration and albumin-to-globulin ratio. Total serum immunoglobulin and serum IgM concentrations were increased. Inapparent carrier horses had significantly decreased percentages of CD5+ and CD4+ blood lymphocytes. CONCLUSIONS: Serum protein and lymphocyte subset changes in EIAV-infected inapparent carrier horses are consistent with immune activation or chronic inflammation, both of which may, in part, be the result of virus-induced polyclonal B-cell activation. CLINICAL RELEVANCE: EIAV seropositive horses have immune-related abnormalities consistent with ongoing viral activity regardless of the duration they have been infected, even when the usual signs of disease (anemia, fever, weight loss) are not apparent.

Animals↗
PubMed1997

Flow cytometric method for detecting thiazole orange-positive (reticulated) platelets in thrombocytopenic horses.

OBJECTIVE: To evaluate a method for detecting thiazole orange-positive (TO+, reticulated) platelets in equine blood, using flow cytometry. ANIMALS: 16 healthy, equine infectious anemia virus (EIAV)-negative horses and ponies; 9 thrombocytopenic, EIAV-positive horses and ponies; and 2 thrombocytopenic, EIAV-negative horses. PROCEDURE: Blood from healthy and thrombocytopenic horses was collected by jugular venipuncture. Appropriate sample requirement and incubation time for the assay were evaluated, using blood anticoagulated with EDTA or sodium citrate, or platelet-rich plasma in sodium citrate. The sample of blood or platelet-rich plasma was incubated with thiazole orange, and flow cytometric analysis was performed. Percentage of circulating TO+ platelets was determined from fluorescence (FL-1) logarithmic histograms. RESULTS: Healthy ponies (n = 9) had 1.28 to 2.83% (mean +/- SD, 2.03 +/- 0.50%) and horses (n = 7) had 0.9 to 3.44% (2.12 +/- 1.14%) TO+ platelets in circulation. Thrombocytopenic ponies (n = 7) had 11.14 to 48.41% (26.51 +/- 11.99%) and thrombocytopenic horses (n = 4) had 2.33 to 8.52% (6.19 +/- 2.68%) TO+ platelets in circulation. Mean platelet counts for the thrombocytopenic ponies and horses were 24,400 +/- 20,500 and 39,300 +/- 13,500 platelets/microliters, respectively (reference range, 94,000 to 232,000 platelets/ microliters). CONCLUSION: Thiazole orange-positive platelets can be detected in equine blood and percentages of TO+ platelets are increased in thrombocytopenic horses. CLINICAL RELEVANCE: Enumeration of TO+ platelets may prove to be a helpful noninvasive clinical measurement of bone marrow platelet production and aid in the assessment of platelet kinetics in thrombocytopenic horses.

Animals↗
PubMed1996

Strong ion difference approach to acid-base imbalances with clinical applications to dogs and cats.

Stewart's strong ion difference, first introduced more than 10 years ago, offers an innovative approach for the analysis of non-respiratory acid-base disorders. This article addresses the concept of strong ion difference and discusses its clinical applications. A brief review of base excess and anion gap is also included. Clinical cases are provided to demonstrate a step-by-step method using strong ion difference to evaluate nonrespiratory acid-base imbalances.

Acid-Base Equilibrium↗
PubMed1996

Phorbol ester stimulation of equine macrophage cultures alters expression of equine infectious anemia virus.

Equine infectious anemia virus (EIAV) is a lentivirus that replicates predominantly in mature tissue macrophages. Viral expression is strongly influenced by the state of differentiation of the host cell. While blood monocytes can be infected, viral transcription is limited until the cell differentiates into a mature macrophage. Activation of mature macrophages infected with EIAV might also alter viral expression, presumably through binding of cellular transcription factors to viral nucleic acid sequences within the long terminal repeat (LTR). Using DNA amplification techniques, we compared LTR sequences of U.S. field strains of EIAV to sequences of a laboratory adapted strain of the virus. All field strain sequences were more closely related to Wyoming strain than to the Malmquist laboratory adapted strain or a previously sequenced infectious molecular clone of EIAV. Primary equine monocyte-derived macrophage cultures were infected with virulent and avirulent strains of EIAV and the effects of macrophage stimulation on EIAV expression were determined. Stimulation of macrophages with phorbol ester activated the cells to secrete tumor necrosis factor alpha (TNF alpha). This activation signal also resulted in a significant downregulation of viral expression as determined by supernatant reverse transcriptase activity. This effect occurred independent of the virulence of the virus strain used or the nucleic acid sequence of the viral LTR. This may represent an adaptive response of EIAV to evade the host immune response and establish a persistent infection.

Animals↗
PubMed1996

Equine infectious anemia virus replication is upregulated during differentiation of blood monocytes from acutely infected horses.

Equine infectious anemia virus is a lentivirus that replicates in mature tissue macrophages of horses. Ponies were infected with equine infectious anemia virus. During febrile episodes, proviral DNA was detectable, but viral mRNA was not detectable. As cultured blood monocytes from these ponies differentiated into macrophages, viral expression was upregulated. In situ hybridization confirmed that viral transcription occurred in mature macrophages.

Acute Disease↗
PubMed1993

Stridor in the infant and child. Assessment, treatment.

The health care team caring for the child with stridor must be familiar with congenital abnormalities of the airway and airway problems resulting from infections and foreign bodies and their typical presentation and endoscopic findings. Teamwork and communication are the keys to safe diagnosis and management of these children.

Child↗
PubMed1993

Squamous cell carcinoma of the anal and perianal area in a bull.

A squamous cell carcinoma located adjacent to the anus was diagnosed in a 15-year-old light colored Longhorn bull. The tumor restricted the anal orifice to a diameter of 3 cm. Upon histological evaluation, islands of squamous cells were present deep in the dermis and the submucosal connective tissue. It was not possible to determine whether the tumor originated from the perianal region or the anus. This is the first diagnosed and reported occurrence in North America of squamous cell carcinoma in the anal region of a bull.

Animals↗
PubMed1976

Kinetic studies of the thermal decomposition of 2-chloroethylphosphonic Acid in aqueous solution.

The decomposition of 2-chloroethylphosphonic acid in aqueous solution has been studied at pH values from 6 to 9 and at temperatures in the 30 to 55 C range. The rate of decomposition is estimated from the rate of formation of ethylene. The rate is proportional to the concentration of the phosphonate dianion and is independent of the hydroxyl ion concentration. The rate constant at 40 C is 1.9 x 10(-4) sec(-1) and the activation energy is 29.8 kcal mol(-1). The rate of reaction is not affected significantly by the presence of potassium iodide or urea (substances which increase the rate of leaf abscission in trees sprayed by 2-chloroethylphosphonic acid). The rate decreases slightly in the presence of low concentrations of magnesium and calcium ions.

Journal Article↗
PubMedDate not supplied

Cochlear implants and the deaf child: a nursing perspective.

Cochlear implants are no longer considered new or experimental technology and are available for children with profound sensorineural hearing loss. Pediatric cochlear implantation requires a multidisciplinary team approach with contributions from surgeons, audiologists, speech-language pathologists, psychologists, nurses, special educators, and parents. The decision to perform cochlear implantation in children must be seriously considered. Some in the deaf community voice strong objections to the procedure. Additionally, it requires an enormous commitment on the part of the family and the health care system in both personal and financial terms. The surgery has some risks, and the rehabilitation period is lengthy. Outcomes are variable, and many factors play a role in a child's successful use of implants. Nonetheless, gradual, steady improvement in speech perception, speech production, and language typically occurs. The approach of Children's Hospital in Boston to the assessment, the surgical procedure, and follow-up is detailed here.

Adolescent↗