Biomedical subjects

W L Hanson

Publications and source records attributed to W L Hanson.

At least 37 records · Page 2Linked to original sources

PubMed1991

Neutrophil kinetics in the pulmonary microcirculation during acute inflammation.

The site of neutrophil interaction with the vasculature during acute lung inflammation is controversial, but has been suggested to occur in the alveolar capillaries, in contrast with its location in postcapillary venules in nonpulmonary tissues. We studied the kinetics of neutrophil accumulation and the site of neutrophil-vascular interaction in the lung by examining directly the behavior of fluorescein isothiocyanate-labeled canine neutrophils utilizing in vivo fluorescence videomicroscopy through a window inserted into the chest wall of anesthetized dogs. The administration of fragments of the fifth component of complement (C5f) into either the airway or pulmonary artery resulted in neutrophil sequestration almost exclusively in pulmonary capillaries. Kinetically, there was a shift in the distribution of neutrophil transit times resulting in a marked prolongation of median transit time. This response occurred within seconds after intravascular C5f and within 5 minutes after airway C5f and was maintained for at least 30 minutes. Ultrastructural studies after airway C5f showed neutrophils in various stages of migration through the alveolar-capillary membrane and more than 90% of these neutrophils were seen to migrate from capillary rather than from venular sites. These data indicate that pulmonary inflammation differs from inflammation in other vascular beds primarily in the site of neutrophil localization and migration. This fundamental difference in the inflammatory response may serve to localize the inflammatory response to the alveolus, and (since cells were retained singly), indicates the inability of leukoaggregation adequately to explain the findings. Leukocyte accumulation in the lung may thus occur through alterations in the balance between delivery of neutrophils to the lung and the transit time of these cells across the capillary bed.

Acute Disease↗

PubMed1991

Development of Leishmania (Viannia) panamensis lesions and relationship of numbers of amastigotes to lesion area on antimony-treated and untreated hamsters.

Young adult (60-70-g) male golden hamsters (Mesocricetus auratus) each were injected intradermally at the dorsal base of the tail with 15 x 10(6) promastigotes of Leishmania (Viannia) panamensis (MHOM/PA/83/WR539), and progression and regression of subsequent lesions were evaluated for up to 17 wk postinfection (PI) as to area, weight, and number of amastigotes within lesions in untreated hamsters and in hamsters treated with meglumine antimoniate (Glucantime). In untreated hamsters total area of lesion, weight, and numbers of amastigotes generally increased rapidly and concomitantly up to 3-4 wk PI. Amastigote numbers tended to decrease from 4 to 11 wk PI and subsequently the numbers of amastigotes within the lesions decreased rapidly, whereas relatively little change occurred in the area and weight of the lesions. Meglumine antimoniate treatment of cutaneous hamster lesions resulted in marked concomitant decrease in size of the lesions and numbers of amastigotes within the lesions examined 1 wk after treatment. Measurement of the area of cutaneous leishmanial lesions thus would appear to be a valid method of evaluating the efficacy of promising compounds against L. panamensis in hamsters when measurements are taken 3-5 wk after experimental infection and reflects the number of amastigotes present in the lesion.

Animals↗

PubMed1990

Suppression of both antimony-susceptible and antimony-resistant Leishmania donovani by a bis(benzyl)polyamine analog.

It was recently demonstrated that a bis(benzyl)polyamine analog (MDL 27695; N,N'-bis(3-[(phenylmethyl)amino]propyl)-1,7-diaminoheptane) possessed potent antimalarial activity in vitro and in vivo (A. J. Bitonti, J. A. Dumont, T. L. Bush, M. L. Edwards, D. M. Stemerick, P. P. McCann, and A. Sjoerdsma, Proc. Natl. Acad. Sci. USA 86:651-655, 1989). We now report that MDL 27695 also has potent antileishmanial activity, eliminating 77 to 100% of Leishmania donovani amastigotes from mouse peritoneal macrophages in vitro at 1 microM. Administration of 15 mg of MDL 27695 per kg three times per day for 5 days to L. donovani-infected mice suppressed parasite burdens in liver, spleen, and bone marrow by 83 to 96, 90, and 87%, respectively, and by 99.9% in livers of mice given the same dose two times per day for 10 days. Liver parasites were suppressed 74% in L. donovani-infected hamsters treated three times per day for 4 days with 5 mg of MDL 27695 per kg. The 50% effective doses for MDL 27695 were 2.5 mg/kg in mice and about 1 mg/kg in hamsters. In hamsters, MDL 27695 was equally effective against both antimony-susceptible and antimony-resistant L. donovani, suggesting a different mechanism of action for the two types of drugs. Coadministration of N1,N4-bis(butadienyl)-butanediamine (MDL 72527) to mice to inhibit host polyamine oxidase, and hence the formation of oxidative metabolites of MDL 27695, did not affect the antileishmanial activity of MDL 27695. Thus, the mechanism of action of MDL 27695 does not appear to be related to its oxidation to toxic metabolites but may involve interference with DNA and RNA syntheses as found previously in Plasmodium falciparum (Bitonti et al., Proc. Natl. Acad. Sci. USA 86:651-655, 1989).

Animals↗

PubMed1990

Berberine derivatives as antileishmanial drugs.

Berberine, a quaternary alkaloid, and several of its derivatives were tested for efficacy against Leishmania donovani and Leishmania braziliensis panamensis in golden hamsters. Tetrahydroberberine was less toxic and more potent than berberine against L. donovani but was not as potent as meglumine antimonate (Glucantime), a standard drug for the treatment of leishmaniasis. Only berberine and 8-cyanodihydroberberine showed significant activity (greater than 50% suppression of lesion size) against L. braziliensis panamensis.

Animals↗

PubMed1990

Pulmonary microcirculatory kinetics of neutrophils deficient in leukocyte adhesion-promoting glycoproteins.

The mechanism that causes neutrophils to sequester in the pulmonary circulation is unknown. Because the CD11/CD18 glycoprotein family on the surface membrane of neutrophils participates in many adhesive interactions with the endothelium, we investigated the role of these proteins in the intravascular sequestration of pulmonary neutrophils. Neutrophils were isolated from normal dogs and from the only living dog known to have leukocyte adhesion deficiency disease, an inherited deficiency of the CD11/CD18 adhesion family. The neutrophils were labeled with fluorescein dye, injected into normal recipient dogs, and their passage through the pulmonary microcirculation was recorded by in vivo videofluorescence microscopy through a transparent thoracic window. Transit times for normal and deficient neutrophils were similar over a wide range of hemo-dynamic conditions. Activation by zymosan-activated plasma, which increases the surface membrane expression of CD11/CD18, prolonged the transit of normal neutrophils but did not alter the transit time of the deficient neutrophils. These results indicate that neutrophil CD11/CD18 adhesion-promoting glycoproteins are not involved in the normal pulmonary sequestration of neutrophils but have a significant role in the arrest of activated neutrophils in the pulmonary capillaries.

Animals↗

PubMed1990

Distribution of pulmonary capillary transit times in recruited networks.

When pulmonary blood flow is elevated, hypoxemia can occur in the fastest-moving erythrocytes if their transit times through the capillaries fall below the minimum time for complete oxygenation. This desaturation is more likely to occur if the distribution of capillary transit times about the mean is large. Increasing cardiac output is known to decrease mean pulmonary capillary transit time, but the effect on the distribution of transit times has not been reported. We measured the mean and variance of transit times in single pulmonary capillary networks in the dependent lung of anesthetized dogs by in vivo videofluorescence microscopy of a fluorescein dye bolus passing from an arteriole to a venule. When cardiac output increased from 2.9 to 9.9 l/min, mean capillary transit time decreased from 2.0 to 0.8 s. Because transit time variance decreased proportionately (relative dispersion remained constant), increasing cardiac output did not alter the heterogeneity of local capillary transit times in the lower lung where the capillary bed was nearly fully recruited.

Animals↗

PubMed1990

Neutrophil kinetics in the pulmonary microcirculation. Effects of pressure and flow in the dependent lung.

Increases in pulmonary arterial pressure or blood flow raise peripheral white cell count by releasing sequestered leukocytes from the lung. The effects of altered hemodynamics, however, on the leukocyte sequestration site and on the distribution of leukocyte transit times through the pulmonary microcirculation are unknown. We used in vivo fluorescence videomicroscopy to study the passage of individual, fluorescein-isothiocyanate-labeled neutrophils through the pulmonary microcirculation of anesthetized dogs. Pulmonary hemodynamics were altered over a wide range. Regardless of the hemodynamic conditions, the only place that any of the 2,919 observed neutrophils stopped was in the capillaries. The periods of immobility had a wide range, from less than 1 to greater than 1,200 s. Because the cells remained motionless once they stopped and then accelerated suddenly as they regained the free-flowing stream, the obstructions must have been discrete. About a quarter of the capillary pathways had one site of high resistance. Another quarter offered two or more obstructions. In the remaining half, the neutrophils passed rapidly and without pause from arteriole to venule. Increases in pressure and flow decreased the number of times that individual cells stopped. These changes altered the median transit time by shifting the distribution of transit times between the slowest and fastest groups. We conclude that most of the total pathlength of perfused capillaries offers little resistance even to neutrophils. There are, however, focal areas in individual capillaries that offer high resistance to neutrophil passage.

Animals↗

PubMed1990

Leishmania braziliensis in the squirrel monkey: development of primary and satellite lesions and lack of cross-immunity with Leishmania donovani.

Three female and 2 male adult laboratory-reared squirrel monkeys (Saimiri sciureus) that previously had been inoculated with Leishmania (Leishmania) donovani and had recovered from experimental visceral leishmaniasis were each inoculated intradermally at the dorsal base of the tail with 2.2 x 10(7) culture-derived promastigotes of Leishmania (Viannia) panamensis. The progression and regression of subsequent lesions were examined for 36 wk in all 5 monkeys after which 3 of the monkeys were killed (1 with a primary lesion and all with satellite lesions) and the 2 surviving monkeys (1 with primary lesion and both with satellite lesions) were treated with 104 mg/kg/day of meglumine antimoniate for 10 days. All of the monkeys developed a primary lesions at the site of injection of the parasite and later developed satellite lesions peripheral to the primary nodule. The primary lesions had disappeared from 3 of the 5 monkeys by 36 wk, whereas satellite lesions persisted on all at this time. Satellite lesions were present at 52 wk after treatment and persisted for 169 wk in the 2 surviving monkeys. The histopathologic appearance of the lesions was characterized as granulomatous inflammation. Our results indicated that squirrel monkeys that had recovered from visceral leishmaniasis remained susceptible to infection with L. (V). panamensis.

Animals↗

PubMed1989

Prostacyclin contributes to inhibition of hypoxic pulmonary vasoconstriction by alkalosis.

The mechanism by which extracellular alkalosis inhibits hypoxic pulmonary vasoconstriction is unknown. We investigated whether the inhibition was due to intrapulmonary production of a vasodilator prostaglandin such as prostacyclin (PGI2). Hypoxic vasoconstriction in isolated salt-solution-perfused rat lungs was blunted by both hypocapnic and NaHCO3-induced alkalosis (perfusate pH increased from 7.3 to 7.7). The NaHCO3-induced alkalosis was accompanied by a significant increase in the perfusate level of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), an hydrolysis product of PGI2. Meclofenamate, an inhibitor of cyclooxygenase, counteracted both the blunting of hypoxic vasoconstriction and the increased level of 6-keto-PGF1 alpha. In intact anesthetized dogs, hypocapnic alkalosis (blood pH increased from 7.4 to 7.5) blunted hypoxic pulmonary vasoconstriction before but not after administration of meclofenamate. In separate cultures of bovine pulmonary artery endothelial and smooth muscle cells stimulated by bradykinin, the incubation medium levels of 6-keto-PGF1 alpha were increased by both hypocapnic and NaHCO3-induced alkalosis (medium pH increased from 7.4 to 7.7). These results suggest that inhibition of hypoxic pulmonary vasoconstriction by alkalosis is mediated at least partly by PGI2.

6-Ketoprostaglandin F1 alpha↗

PubMed1989

Site of recruitment in the pulmonary microcirculation.

Increasing the total surface area of the pulmonary blood-gas interface by capillary recruitment is an important factor in maintaining adequate oxygenation when metabolic demands increase. Capillaries are known to be recruited during conditions that raise pulmonary blood flow and pressure. To determine whether pulmonary arterioles and venules are part of the recruitment process, we made in vivo microscopic observations of the subpleural microcirculation (all vessels less than 100 microns) in the upper lung where blood flow is low (zone 2). To evoke recruitment, pulmonary arterial pressure was elevated either by an intravascular fluid load or by airway hypoxia. Of 209 arteriolar segments compared during low and high pulmonary arterial pressures, none recruited or derecruited. Elevated arterial pressure, however, did increase the number of perfused capillary segments by 96% with hypoxia and 165% with fluid load. Recruitment was essentially absent in venules (4 cases of recruitment in 289 segments as pressure was raised). These data support the concept that recruitment in the pulmonary circulation is exclusively a capillary event.

Animals↗

PubMed1989

Experimental visceral leishmaniasis in the opossum.

Adult wild-trapped opossums were infected with Leishmania donovani (Khartoum strain, WR 378) and evaluated as an animal model of visceral leishmaniasis. All infected opossums died within 32 days. Loss of body fat, hepatomegaly, and petechiae of skin and abdominal musculature were seen at necropsy. Microscopically, numerous amastigote-laden macrophages were seen in histologic sections of liver, spleen, and lymph nodes; fewer parasite-laden macrophages were in the bronchial-associated lymphoid tissues and renal glomeruli. Hematological findings included thrombocytopenia (terminal), neutropenia, and lymphopenia. Blood lymphocyte blastogenesis in response to concanavalin A and phytohemagglutinin was decreased markedly at day 24 post-infection (PI). Serum antibodies (1:40 dilution) to promastigotes of L. donovani were detected in five of eight infected opossums tested on days 10 and 24 PI. Total bilirubin concentrations and alanine aminotransferase and aspartate aminotransferase activities were increased after day 25 PI. Activated partial thromboplastin times and one-stage prothrombin times were prolonged before death. Concurrently, factors V, VIII, and XII activities were decreased.

Animals↗

PubMed1989

Chemotherapy of experimental visceral leishmaniasis in the opossum.

Visceral leishmaniasis is a severe chronic disease of people and animals. The disease is caused by several subspecies of a protozoal organism, Leishmania donovani. If not treated, visceral leishmaniasis is often fatal. The most commonly used chemotherapeutic agents to treat the disease are pentavalent antimonials, which can be toxic, must be administered by parenteral routes, and are sometimes ineffective. In this study, meglumine antimoniate, a pentavalent antimony, was compared with WR 6026, an 8-aminoquinoline derivative, as to antileishmanial efficacy. The results indicate that either of these 2 drugs are effective in the suppression of amastigotes in the liver and spleen of the opossum. Despite the marked parasite suppression in the liver and spleen of the infected opossums, the experimental disease was fatal in all of the infected opossums, regardless of the therapy.

Aminoquinolines↗

PubMed1989

A comparison of experimental visceral leishmaniasis in the opossum, armadillo and ferret.

Visceral leishmaniasis is a severe, chronic protozoal disease of humans and animals. Although chemotherapeutic agents are available for the treatment of this disease, problems such as drug toxicity, drug ineffectiveness and drug resistance of the parasite are responsible for treatment failures. To determine whether a drug is a potential antileishmanial agent, screening tests are performed using in vitro and in vivo models. Subsequently, a study using an appropriate animal model is performed to clearly determine the efficacy of a drug against Leishmania. Due to current public concerns regarding the use of companion animals in addition to the high costs of obtaining and maintaining these animals for research use, conventional animal models used in these chemotherapy studies, notably the dog and monkey, are becoming less acceptable. Therefore, new, less expensive and more accessible animal models are needed for the study of antileishmanial compounds. In this study, the armadillo, ferret and opossum were evaluated as possible new animal models for visceral leishmaniasis. The marked body weight loss, hepatomegaly, splenomegaly, large amastigote densities and the microscopic lesions observed in the infected opossums indicated that the opossum was more susceptible to visceral leishmaniasis than the armadillo or ferret.

Animals↗

PubMed1988

Partial purification and characterization of acid phosphatase from sporulated oocysts of Eimeria tenella.

Acid phosphatase of Eimeria tenella oocysts (Peak II) was purified 77-fold with a recovery of 26% using protamine sulfate precipitation, DEAE-cellulose chromatography and Sephadex G-200 gel filtration. This enzyme occurs in multiple forms as indicated by two peaks which can be separated by DEAE-cellulose chromatography and polyacrylamide gel electrophoresis. The partially purified enzyme has optimal activity at pH 4.5. With p-nitrophenyl phosphate the Km and Vmax values for (Peak II) were 25 mM and 1.57 mumol/min/mg protein, respectively. The enzyme (Peak II) is strongly inhibited by Hg++, Cu++, iodoacetamide, fluoride and molybdate. Tartrate and other divalent metal ions have no effect on enzyme activity. The partially purified Peak II phosphatase is not a glycoprotein as it is not absorbed on concanavalin-A Sepharose and its treatment with bacterial neuraminidase does not alter its elution profile through DEAE cellulose.

Acid Phosphatase↗

PubMed1987

Comparison of arylsulphatases from Eimeria tenella (parasite) and chicken caecum (host).

Chicken caecal arylsulphatase was purified 700-fold by (NH4)2SO4 fractionation, concanavalin A-Sepharose and cyclic AMP-Sepharose chromatographies. The purified enzyme was a glycoprotein of Mr 97,000. It hydrolysed p-nitrocatechol sulphate, cerebroside 3-sulphate and ascorbic acid 2-sulphate and was strongly inhibited by Na2SO4 (Ki = 50 microM) and Na3PO4 (Ki = 20 microM). Arylsulphatase from Eimeria tenella sporozoites was purified 28-fold by (NH4)2SO4 fractionation. Arylsulphatase of E. tenella sporozoites was not a glycoprotein. It had an Mr of 49,000. It was inhibited by Na2SO4 (Ki = 300 microM), sodium phosphate (Ki = 90 microM) and heparin. It hydrolysed ascorbic acid 2-sulphate, but cerebroside 3-sulphate was not desulphated. The kinetic parameters of chicken caecal arylsulphatase were different from those of the E. tenella enzyme.

Animals↗

PubMed1987

Activity of purine analogs against Leishmania donovani in vivo.

The dose of orally administered 9-deazainosine calculated to suppress 50% of Leishmania donovani amastigotes in hamster livers was 19 mg/kg (body weight) per day; 96 to 99% of Leishmania organisms were eliminated from the liver and spleen of squirrel monkeys by 50 mg/kg per day. Because these activities were greater than that of the experimental clinical agent allopurinol and comparable to that of the classical agent parenteral pentavalent antimony, 9-deazainosine should be considered for clinical development for visceral leishmaniasis.

Administration, Oral↗

PubMed1987

Physiological neutrophil sequestration in the lung: visual evidence for localization in capillaries.

Although the lung is known to be a major site of neutrophil margination, the anatomic location of these sequestered cells within the lung is controversial. To determine the site of margination and the kinetics of neutrophil transit through the pulmonary microvasculature, we infused fluorescein isothiocyanate-labeled canine neutrophils into the pulmonary arteries of 10 anesthetized normal dogs and made fluorescence videomicroscopic observations of the subpleural pulmonary microcirculation through a window inserted into the chest wall. The site of fluorescent neutrophil sequestration was exclusively in the pulmonary capillaries with a total of 951 labeled cells impeded in the capillary bed for a minimum of 2 s. No cells were delayed in the arterioles or venules. Transit times of individual neutrophils varied over a wide range from less than 2 s to greater than 20 min with an exponential distribution skewed toward rapid transit times. These observations indicate that neutrophil margination occurs in the pulmonary capillaries with neutrophils impeded for variable periods of time on each pass through the lung. The resulting wide distribution of transit times may determine the dynamic equilibrium between circulating and marginated neutrophils.

Animals↗

PubMed1987

Pulmonary arterial transit times.

To begin to characterize the pulmonary arterial transport function we rapidly injected a bolus containing a radiopaque dye and a fluorescence dye into the right atrium of anesthetized dogs. The concentrations of the dye indicators were measured in the main pulmonary artery (fluoroscopically) and in a subpleural pulmonary arteriole (by fluorescence microscopy). The resulting concentration vs. time curves were subjected to numerical deconvolution and moment analysis to determine how the bolus was dispersed as it traveled through the arteriole stream tube from the main pulmonary artery to the arteriole. The mean transit time and standard deviation of the transport function from the main pulmonary artery to the arterioles studied averaged 1.94 and 1.23 s, respectively, and the relative dispersion (ratio of standard deviation to mean transit time) was approximately 64%. This relative dispersion is at least as large as those reported for the whole dog lung, indicating that relative to their respective mean transit times the dispersion upstream from the arterioles is comparable to that taking place in capillaries and/or veins. The standard deviations of the transport functions were proportional to their mean transit times. Thus the relative dispersion from the main pulmonary artery to the various arterioles studied was fairly consistent. However, there were variations in mean transit time even between closely adjacent arterioles, suggesting that variations in mean transit times between arteriole stream tubes also contribute to the dispersion in the pulmonary arterial tree.

Animals↗