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Biomedical subjects

B D Hansen

Publications and source records attributed to B D Hansen.

At least 19 recordsLinked to original sources
PubMed2004

High microsatellite diversity and differential structuring among populations of the introduced common brushtail possum, Trichosurus vulpecula, in New Zealand.

An understanding of genetic variation and structure of pest populations has the potential to improve the efficiency of measures to control them. Genetic analysis was undertaken at five microsatellite loci in four native Australian and 14 introduced New Zealand populations of the common brushtail possum Trichosurus vulpecula in order to document these parameters. Genetic variation in New Zealand populations, and phylogenetic relationships among Australian and New Zealand populations, were largely predicted by the recorded introduction history. Populations on the two main islands of New Zealand had only slightly lower genetic diversity than did Australian populations, except that allelic richness on the South Is. was significantly lower. Diversity was higher in North Is. than in South Is. populations (although not significantly so) and mainland New Zealand populations as a group were significantly more diverse than offshore islands that represented secondary population size bottlenecks. In phylogenetic analyses South Is. and offshore island populations grouped with Tasmania, while North Is. populations grouped either with mainland Australia or were intermediate between the two Australian sources. This scheme was supported by admixture coefficients showing that North and South Is./offshore island populations were largely mainland Australian and Tasmanian in origin, respectively. Population structure differed markedly between the North and South Islands: populations were typically more genetically differentiated on the former than the latter, which also showed significant isolation-by-distance. Substantial linkage disequilibrium in most sampled New Zealand but no Australian population between microsatellite loci Tv16 and Tv27 suggests they may be physically linked.

Animals↗
PubMed1998

Immunological and molecular characterization of three variant subtype P1.14 strains of Neisseria meningitidis.

Epidemic outbreaks of group B meningococcal disease exhibit a clonal nature consisting of a common serotype-subtype. Subtype-specific monoclonal antibodies (MAbs) directed toward two variable regions (VR1 and VR2) of the class 1 protein of Neisseria meningitidis are used in this classification scheme. A new MAb was developed to classify a nonsubtypeable (NST) strain of N. meningitidis, 7967. This MAb bound to both the NST strain and the prototype subtype P1. 14 strain, S3446, by dot blot analysis. However, a MAb produced to the prototype P1.14 strain did not bind to strain 7967. Sixteen additional strains were further identified as P1.14 with the prototype MAb; of these, 15 strains bound both MAbs. Differences in the characteristics of binding of both antibodies to the three apparently diverse P1.14 strains were studied further by using outer membrane complex proteins, immobilized peptides, and soluble peptides. Deduced amino acid analysis suggested that both MAbs bind to VR2 and that single amino acid changes within VR2 (KM, NM, or KK) might explain the differences in binding characteristics. These results demonstrated that minor variations which exist within subtype variable regions may be clearly identified only by a combination of molecular and immunologic testing. The impact of subtype variation will become more evident as subtype-specific vaccines are developed and tested for efficacy.

Amino Acid Sequence↗
PubMed1996

Evaluation of a hypertonic sodium chloride/dextran solution for treatment of traumatic shock in dogs.

OBJECTIVE: To compare the efficacy of 7% NaCl solution (hypertonic saline) in 6% dextran 70 solution (HSD) with that of lactated Ringer's solution (LRS) for treatment of dogs in traumatic shock. DESIGN: Prospective, randomized, clinical study. ANIMALS: 16 traumatized adult dogs with clinical signs of shock. PROCEDURE: Physical, hemodynamic, blood gas, and clinical chemistry measurements were performed prior to treatment. Initial treatment consisted of HSD (n = 8) or LRS (n = 8) administered as a bolus (5 ml/kg of body weight, IV) over a 3-minute period, followed by administration of additional LRS and other treatments to restore hemodynamic and physical criteria to within reference limits. Measurements were repeated for 3 hours after initial treatment. The volumes of LRS and HSD administered were recorded hourly. Degree of injury was scored by using a trauma severity index. RESULTS: Dogs responded similarly to the treatments, and all but 3 dogs survived to be discharged. The amount of fluid administered to dogs in the HSD group over the final 2 hours of the study was significantly less than that administered to the dogs in the LRS group. Serum sodium concentration and osmolality of the dogs in the HSD group were not significantly greater than those values in the LRS group. Bradyarrhythmias were observed in 2 dogs in the HSD group. CLINICAL IMPLICATIONS: Hypertonic sodium chloride/dextran solution is safe and effective for resuscitating dogs in traumatic shock. Seven percent NaCl in 6% dextran 70 may reduce the need for isotonic fluids in the hours after initial resuscitation.

Accidents, Traffic↗
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↗
PubMed1992

Loss of infectivity by progeny virus from alpha interferon-treated human immunodeficiency virus type 1-infected T cells is associated with defective assembly of envelope gp120.

Levels of human immunodeficiency virus (HIV) DNA, RNA, or p24 antigen and reverse transcriptase activity in T-cell cultures treated with 500 IU of recombinant alpha interferon (rIFN alpha) per ml were comparable to those in control cultures. Radioimmunoprecipitation analysis of proteins in lysates of IFN-treated T cells documented a marked accumulation of HIV proteins. Localization of gp120 by immunofluorescence showed a diffuse pattern in IFN-treated cells quite distinct from the ring pattern in untreated control cells. That large quantities of gp120 in aberrant cell compartments might affect HIV morphogenesis was confirmed in infectivity studies: virions from IFN-treated cells were 100- to 1,000-fold less infectious than an equal number of virions from control cells. Direct examination of IFN-treated and control HIV-infected cells by transmission electron microscopy showed little difference in the number or distribution of viral particles. However, quantitation of gp120 by immunogold particle analysis revealed a marked depletion of envelope glycoprotein in virions released from IFN-treated cells. This defect in gp120 assembly onto mature viral particles provides a molecular basis for this loss of infectivity.

Cells, Cultured↗
PubMed1991

[Anesthesia for single-day orthopedic surgery].

During the period 1 January 1989 to 31 December 1989, a total of 1,004 patients were submitted to outpatient single-day surgery in Aalborg Hospital. As fas as possible, the patients were anaesthetized with propofol (Diprivan)/alfentanil (Rapifen) and oxygen and atmospheric air. This form of anaesthesia was found to be rapid and suitable for single-day surgery. 8.1% of the patients required admission for further observation, 2.3% of these on account of anaesthesiological complications. It is concluded that, by means of meticulous planning, it is possible to carry out ambulant anaesthesia and surgery and, employing limited staff resources, it has proved possible to reduce the waiting time for outpatient intervention to 10-12 weeks.

Adolescent↗
PubMed1990

Characterization of the interaction between recombinant human interferon-gamma and its receptor on human polymorphonuclear leukocytes.

The interaction of human recombinant interferon-gamma (rIFN-gamma) with human polymorphonuclear cells (PMN) was investigated. Bolton-Hunter radioiodinated rIFN-gamma bound to PMN in a specific and saturable manner. Eleven hundred binding sites were observed with a Ka of 0.56 x 10(10) M-1. Binding to PMN was rapid with a K1 of 9 x 10(5) M-1 sec-1 at 4 degrees C. At 37 degrees C binding was complete within 6 min. About 50% of bound ligand was internalized within 30 min at 37 degrees C. The receptor demonstrated moderate lability at 37 degrees C in culture. After 1 h at 37 degrees C, PMN lost 80% of their 125I-rIFN-gamma binding sites. This loss was reversed in part by the presence of interleukin-1 in the culture, but not tumor necrosis factor. These studies provide a framework for further investigation into the signalling process of rIFN-gamma on PMN.

Humans↗
PubMed1990

A rapidly progressing lethal case of neuroleptic malignant syndrome.

A fast progressing lethal case of neuroleptic malignant syndrome (NMS) complicated by disseminated intravascular coagulation (DIC) is presented. The fulminant course is infrequent and relates NMS to malignant hyperthermia. Muscular relaxation in combination with fluid load dramatically decreased the temperature, but the catastrophic course of this case was so advanced that the currently recommended treatment of NMS was impossible.

Adult↗
PubMed1990

Restriction of HIV replication in infected T cells and monocytes by interferon-alpha.

Human recombinant interferon-alpha (IFN alpha) restricted viral replication in human immunodeficiency virus- (HIV) infected T cells and monocytes. With T cells, reverse transcriptase (RT) activity in culture fluids was reduced threefold from that of control infected cells by IFN treatment, but HIV p24 antigen levels were unchanged. In contrast, levels of p24 antigen and RT activity in lysates of IFN-treated infected cells were threefold greater than those of controls. These differences suggest that the mechanism for IFN-induced antiviral effects in HIV-infected T cells resides in the terminal events (assembly and release) of the virus replication cycle. Monocytes treated with IFN at the time of virus challenge showed no p24 antigen or RT activity, no HIV-specific mRNA, and no proviral DNA in cells for up to 3 weeks after infection. IFN treatment of chronically infected monocytes also decreased virus replication, as assessed by p24 antigen, mRNA and RT detection assays. However, levels of proviral DNA in the IFN-treated and control HIV-infected cells were indistinguishable. The presence of large quantities of proviral DNA in cells with little or no evidence for active transcription documents a situation approaching true microbiological latency.

DNA, Viral↗
PubMed1990

Macrophages as susceptible targets for HIV infection, persistent viral reservoirs in tissue, and key immunoregulatory cells that control levels of virus replication and extent of disease.

Although macrophages are major targets for human immunodeficiency virus (HIV) infection in vivo, study of HIV-macrophage interactions in vitro was hindered because many laboratory strains of HIV would not replicate in macrophages, and because survival of macrophages in culture was poor. Addition of purified macrophage colony-stimulating factor (M-CSF) to cultured macrophages markedly improves their survival, but does not induce proliferation. HIV isolates that replicate in macrophages will also replicate in lymphocytes; however, isolates adapted to lymphoid cells (such as HIV-HTLVIIIB) will not replicate in macrophages. The envelope gene appears to be a major determinant of the cell tropism of viral isolates. T-cell grown virus stocks synthesize abundant gp120, while virus grown in macrophages contains relatively much less gp120. Electron microscopy of virions from macrophages shows them to be depleted of gp120 surface "spikes." Recombination studies show that the portion of the genome coding for the envelope glycoprotein appears to determine cell tropism. Lastly, rsCD4 neutralized macrophage-tropic isolates less efficiently than T-cell tropic isolates. HIV replication in macrophages is partially under the control of cellular factors, although these have been less well characterized than they have in lymphocytes.

Disease Susceptibility↗
PubMed1985

Fluorogenic substrate detection of viable intracellular and extracellular pathogenic protozoa.

Viable Leishmania promastigotes and amastigotes were detected by epifluorescence microscopy with fluorescein diacetate being used to mark living parasites and the nucleic acid-binding compound ethidium bromide to stain dead cells. This procedure is superior to other assays because it is faster and detects viable intracellular as well as extracellular Leishmania. Furthermore, destruction of intracellular pathogens by macrophages is more accurately determined with fluorescein diacetate than with other stains. The procedure may have applications in programs to develop drugs and vaccines against protozoa responsible for human and animal disease.

Animals↗
PubMed1984

Leishmania mexicana: purine metabolism in promastigotes, axenic amastigotes, and amastigotes derived from Vero cells.

Leishmania mexicana mexicana promastigotes, axenic amastigotes, and amastigotes derived from Vero cells were examined for de novo purine synthesis and mechanisms of purine salvage. Both promastigotes and axenic amastigotes were incapable of de novo purine synthesis, as shown by the lack of [14C]formate and [14C]glycine incorporation into purine nucleotide pools. However, the ready incorporation of [14C]hypoxanthine, [14C]adenine, and [14C]guanine suggested that purine salvage pathways were operating. In addition, a significant percentage (greater than or equal to 60%) of the total label from these purine precursors was associated with adenylate nucleotides. Nucleotide pool levels of axenic amastigotes were consistently greater but the specific activities were less than those of promastigotes, suggesting a slower rate of purine metabolism in the axenic amastigote form. Similar results were obtained from amastigotes isolated from infected Vero cells.

Adenine↗
PubMed1982

The specificity of purine base and nucleoside uptake in promastigotes of Leishmania braziliensis panamensis.

Promastigotes of Leishmania braziliensis panamensis absorbed the purines adenine, hypoxanthine, adenosine and inosine by a combination of diffusion and mediated components. When the uptake rates for these substrates were corrected for diffusion and compared, the purine bases adenine and hypoxanthine were transported at a significantly slower rate than the purine nucleosides adenosine and inosine. Competitive interactions among those purines tested confirmed the presence of mediated and diffusion components and suggested that three transport loci may be operating (Fig. 6). The first transport locus, designated Locus 1, transported inosine, Locus 2, the purine bases hypoxanthine and adenine and Locus 3, adenosine. In addition, adenine and hypoxanthine inhibited the uptake of one another competitively. A comparison of Ki values derived from double reciprocal plots of labelled hypoxanthine and adenine uptake in the presence of the unlabelled substrates as inhibitors suggested that adenine has a greater affinity for the transport locus.

Adenine↗
PubMed1980

Purine base and nucleoside uptake in Plasmodium berghei and host erythrocytes.

The absorption of 3H-labeled adenine, adenosine, hypoxanthine, and 14C-labeled inosine by normal rat erythrocytes, Plasmodium bergheri-infected erythrocytes and saponin released "free parasites" was measured. The uptake of these labeled substrates by normal rat erythrocytes occurs both by diffusion and mediated transport systems. Similar absorptive mechanisms for these substrates also were observed for both Plasmodium berghei-infected erythrocytes and "free parasites." Data from inhibition studies using purine base and nucleoside analogues indicate the presence of three distinct transport loci in the normal erythrocyte for adenosine-inosine, hypoxanthine, and adenine and two loci in the infected erythrocyte and "free parasite" for adenosine-inosine-hypoxanthine and adenine. The initial metabolism of 3H-adenosine by the "free parasite" also was examined. A double isotope technique was used to follow the separate metabolic fates of the purine base and ribose moieties of adenosine. The data suggest a possible conversion of adenosine to the purine base and ribose moiety and subsequent uptake of the purine base by the parasite. In addition, a powerful adenosine deaminase inhibitor (2-deoxcoformycin) significantly reduced the uptake of 3H-adenosine by the "free parasites." Chromatographs of aliquots from postincubation media show the tritium label to be associated predominately with adenosine in the presence of 2-deoxycoformycin and with isoine and hypoxanthine in the absence of the inhibitor.

Adenine↗