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Biomedical subjects

J L Olsen

Publications and source records attributed to J L Olsen.

11 recordsLinked to original sources
PubMed1995

Evolution of nuclear rDNA ITS sequences in the Cladophora albida/sericea clade (Chlorophyta).

Ribosomal DNA ITS sequences were compared among 13 different species and biogeographic isolates from the monophyletic "albida/sericea clade" in the green algal genus Cladophora. Six distinct ITS sequence types were found, characterized by multiple insertions and deletions and high levels of nucleotide substitution. Conserved domains within the ITS regions indicate the presence of ITS secondary structure. Low transition/transversion ratios among the six types and nearly symmetrical tree-length frequency distributions indicate some saturation, and low phylogenetic signal. Although branching order among five of the six ITS sequence types could not be resolved, estimates of ITS sequence divergence as compared with 18S divergence in a subset of the taxa suggests that the origin of the different ITS types is probably in the mid-Miocene (12 Ma ago) but that biogeographic isolates within a single ITS type (including both Pacific and Atlantic representatives) have probably dispersed on a time scale of thousands rather than millions of years.

Base Sequence↗
PubMed1994

The Cladophora complex (Chlorophyta): new views based on 18S rRNA gene sequences.

Evolutionary relationships among species traditionally ascribed to the Siphonocladales/Cladophorales have remained unclear due to a lack of phylogenetically informative characters and extensive morphological plasticity resulting in morphological convergence. This study explores some of the diversity within the generic complex Cladophora and its siphonocladalaen allies. Twelve species of Cladophora representing 6 of the 11 morphological sections recognized by van den Hoek were analyzed along with 8 siphonocladalaen species using 18S rRNA gene sequences. The final alignment consisted of 1460 positions containing 92 phylogenetically informative substitutions. Weighting schemes (EOR weighting, combinatorial weighting) were applied in maximum parsimony analysis to correct for substitution bias. Stem characters were weighted 0.66 relative to single-stranded characters to correct for secondary structural constraints. Both weighting approaches resulted in greater phylogenetic resolution. Results confirm that there is no basis for the independent recognition of the Cladophorales and Siphonocladales. The Siphonocladales is polyphyletic, and Cladophora is paraphyletic. All analyses support two principal lineages, of which one contains predominantly tropical members including almost all siphonocladalean taxa, while the other lineage consists of mostly warm- to cold-temperate species of Cladophora.

Base Sequence↗
PubMed1984

The effects of high fat feeding during one cycle of reproduction consisting of pregnancy, lactation and recovery on body composition and fat pad cellularity in the rat.

The changes in adipose depot weight, cell size, cell number and body composition during pregnancy, lactation and recovery were studied in Osborne-Mendel rats fed standard or high fat diets. Rats were killed on day 21 of pregnancy, after 21 days of lactation, and after 21 or 22 days of a postlactational recovery period. Nonpregnant control groups were killed at the beginning and at the conclusion of the experimental period. The high fat-fed, mated group was always fatter than similarly treated animals fed standard diets throughout pregnancy and lactation. However, by the end of the recovery period, carcass composition of the animals fed high fat or standard diets and the nonpregnant groups were not statistically different. The weight of the parametrial, retroperitoneal and subscapular depots was higher in the high fat-fed animals at the end of the recovery period, and in the latter two pads, this increase was statistically significant. Thus, despite the extensive lipid mobilization that occurs during lactation, the high fat-fed animals appear to be predisposed to postpartum obesity.

Adipose Tissue↗
PubMed1981

A review of parenteral sustained-release naltrexone systems.

The ideal naltrexone sustained-release delivery system should be easy to inject or implant, not cause adverse tissue reaction, release the drug at a relatively constant rate for at least 30 days, and biodegrade within a short time afterwards. Mechanisms which can be used for sustaining drug release include reducing solubility and surface area, coating, encapsulation and microencapsulation, complexation, binding and hydrophilic gelation. Drug release from such systems is controlled by diffusion through a barrier/film, diffusion from a monolithic device, erosion of the surface, hydrolysis, ion exchange, biodegradation, or a combination of these. Injectable systems would seem to be ultimately preferred because of the ease of administration and handling, while the implantable devices may find first use in man since they are easily removable, should that be necessary. Maintaining particulate-free products and sterilization methods are two problems with all parenteral dosage forms. Production must be particularly well controlled and validated.

Biodegradation, Environmental↗
PubMed1981

Solid solutions as long-acting naltrexone delivery systems.

Solid solutions and solid dispersions have been used both to increase and to decrease solubility. Solid solutions may extend the release of naltrexone depending upon composition and production methods. Several combinations of naltrexone and cholesterol esters were prepared and evaluated. These combinations did prolong release of the drug in some cases, but none acceptably long enough. Preparation of these solutions and dispersions involved compression and heat as well as solvent mixing. Drug release from particles is dependent upon surface area, composition, and method of preparation. Suspendable, injectable particles can be produced which will give acceptable release rates. The preparation and evaluation are complex and will require much more research effort.

Analgesics↗
PubMed1977

Efficacy of dichlorvos administered orally in single and repeated doses for removal of canine whipworms.

A single dose of dichlorvos (2,2-dichlorovinyl dimethyl phosphate) was administered orally at a dosage of 30 mg/kg to 19 dogs naturally infected with Trichuris vulpis and to 13 dogs experimentally infected with T vulpis. Based on the presence or absence of whipworm eggs in the feces, 10 to 14 days after treatment, dogs were either killed and the number of remaining worms counted, or the dogs were given a 2nd treatment. After the initial treatment, 18 dogs had a mean of 0.5 worms (SD +/- 0.5) remaining, and 14 dogs had a mean of 55 worms (SD +/- 85) remaining. After these 14 dogs were given a 2nd treatment, the number of womrs remaining decreased to a mean of 14 (SD +/- 28). Although a high degree of efficacy was attained in 56% of the dogs after the 1st dose, the data suggested that additional treatment may often be necessary.

Animals↗
PubMed1977

Bronchial effects of aerosolized delta 9-tetrahydrocannabinol in healthy and asthmatic subjects.

Effects on airway dynamics, heart rate, and the central nervous system of various doses of delta9-tetrahydrocannabinol administered in a random, double blind fashion using a Freon-propelled, metered-dose nebulizer were evaluated in 11 healthy men and 5 asthmatic subjects. Effects of aerosolized delta9-tetrahydrocannabinol were compared with aerosolized placebo and isoproterenol and with 20 mg of oral and smoked delta9-tetrahydrocannabinol. In the normal subjects, after 5 to 20 mg of aerosolized delta9-tetrahydrocannabinol, specific airway conductance increased immediately, reached a maximum (33 to 41 per cent increase) after 1 to 2 hours, and remained significantly greater than placebo values for 2 to 3 hours. The bronchodilator effect of aerosolized delta9-tetrahydrocannabinol was less than that of isoproterenol after 5 min, but significantly greater than that of isoproterenol after 1 to 3 hours. The magnitude of bronchodilatation after all doses of aerosolized delta9-tetrahydrocannabinol was comparable, but 5 mg of delta9-tetrahydrocannabinol caused a significantly smaller increase in heart rate and level of intoxication than the 20-mg dose. Smoked delta9-tetrahydrocannabinol produced greater cardiac and intoxicating effects than either aerosolized or oral delta9-tetrahydrocannabinol. Side effects of aerosolized delta9-tetrahydrocannabinol included slight cough and/or chest discomfort in 3 of the 11 normal subjects. Aerosolized delta9-tetrahydrocannabinol caused significant bronchodilatation in 3 of 5 asthmatic subjects, but caused moderate to severe bronchoconstriction associated with cough and chest discomfort in the other 2. These findings indicate that aerosolized delat9-tetrahydrocannabinol, although capable of causing significant bronchodilatation with minimal systemic side effects, has a local irritating effect on the airways, which may make it unsuitable for therapeutic use.

Adult↗