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Biomedical subjects

P Olson

Publications and source records attributed to P Olson.

At least 19 recordsLinked to original sources
PubMed1995

Highly efficient eukaryotic gene expression vectors for peptide secretion.

Recently, we constructed a series of highly efficient universal eukaryotic gene expression vectors (Sheay et al., BioTechniques 15:856-862, 1993). Such vectors contain a viral promoter and enhancer followed by the adenovirus tripartite leader sequence, a multiple cloning site for the insertion of the gene of interest and a polyadenylation sequence. To enable expression of peptides to be secreted into the tissue culture medium or to be incorporated into the cell membrane, several modifications have been introduced into such vectors: stop codons in all three reading frames were inserted at the end of the multiple cloning site and a DNA sequence coding for a signal peptide for transport through the endoplasmatic reticulum (ER) was introduced downstream of the adenovirus tripartite leader sequence followed by two unique restriction enzyme recognition sites. A protocol is described that allows fast and easy cloning of peptide-coding regions, i.e., PCR products, for expression and secretion. The transport of a genetically engineered chimeric transmembrane protein connected to this ER leader sequence was as efficient as that of the original protein from which the ER sequence has been derived. These universal vectors can also be used for the easy construction of any chimeric transmembrane or secretion proteins.

Amino Acid Sequence↗
PubMed1994

Improved self-inactivating retroviral vectors derived from spleen necrosis virus.

Self-inactivating (SIN) retroviral vectors contain a deletion spanning most of the right long terminal repeat's (LTR's) U3 region. Reverse transcription copies this deletion to both LTRs. As a result, there is no transcription from the 5' LTR, preventing further replication. Many previously developed SIN vectors, however, had reduced titers or were genetically unstable. Earlier, we reported that certain SIN vectors derived from spleen necrosis virus (SNV) experienced reconstitution of the U3-deleted LTR at high frequencies. This reconstitution occurred on the DNA level and appeared to be dependent on defined vector sequences. To study this phenomenon in more detail, we developed an almost completely U3-free retroviral vector. The promoter and enhancer of the left LTR were replaced with those of the cytomegalovirus immediate-early genes. This promoter swap did not impair the level of transcription or alter its start site. Our data indicate that SNV contains a strong initiator which resembles that of human immunodeficiency virus. We show that the vectors replicate with efficiencies similar to those of vectors possessing two wild-type LTRs. U3-deleted vectors carrying the hygromycin B phosphotransferase gene did not observably undergo LTR reconstitution, even when replicated in helper cells containing SNV-LTR sequences. However, vectors carrying the neomycin resistance gene did undergo LTR reconstitution with the use of homologous helper cell LTR sequences as template. This supports our earlier finding that sequences within the neomycin resistance gene can trigger recombination.

Base Sequence↗
PubMed1993

Radiologic case study. Macrodystrophia lipomatosa.

Macrodystrophia lipomatosa is a rare form of gigantism involving an extremity consisting of predominately fibroadipose tissue. Radiographically, it appears as hypertrophy of soft tissues and bone. CT and MR scanning delineate the tissues involved and are virtually diagnostic, demonstrating the predominantly adipose component as well as the overgrowth of the bones, nerves, and vessels also involved.

Adult↗
PubMed1992

Unusually high frequency of reconstitution of long terminal repeats in U3-minus retrovirus vectors by DNA recombination or gene conversion.

Recently, we described a retrovirus vector system with which to study formation of cDNA genes (R. Dornburg and H. M. Temin, Mol. Cell. Biol. 6:2328-2334, 1988; Mol. Cell. Biol. 8:64-72, 1990; J. Virol. 64:886-889, 1990). For these studies, retrovirus vectors were constructed in which the U3 region of the 3' long terminal repeat (LTR) was deleted. After one round of retrovirus replication, such vectors formed a provirus with two U3-minus LTRs. However, the insertion of some additional sequences into such vectors promoted vector rearrangements with an efficiency greater than 95%. Such rearranged vectors behaved like vectors with two wild-type LTRs. Proviruses derived from such vectors were investigated by Southern blot analysis, polymerase chain reaction, and DNA sequencing. We found that the U3 region was reconstituted, resulting in vectors with LTRs like wild-type virus. The sequences that reconstituted the U3 region of the vector LTR were derived from LTR sequences present in the helper cell. Since no retroviral protein coding sequences were detected in infected target cells, recombination of vector sequences with coencapsidated helper cell sequences during reverse transcription seems very unlikely. Thus, it appears that the recombination (or gene conversion) events leading to a vector with reconstituted LTRs occurred at the DNA level. The high frequency of this recombination (or gene conversion) was dependent on internal vector sequences.

Animals↗
PubMed1991

Iatrogenic renal disease.

We studied iatrogenic problems in nephrology by classifying all patients for nephrology consultation into nine presenting syndromes and seven etiologic groups. One hundred (2.2%) of all admissions were seen in nephrology consultation. Acute renal failure was the most common presenting syndrome, accounting for 59% of the consultations. Forty-one of the 100 consultations (1% of all admissions) had a renewal syndrome of iatrogenic origin. Of these 41 patients, 38 had acute renal failure and three had fluid and electrolyte problems. Twenty of the 41 patients had drug-induced problems. Eighteen of these patients were dehydrated, and in three patients, acute renal failure occurred after surgery. Of the 20 patients with iatrogenic renal problems caused by drugs, seven problems were antibiotic related, five were due to diuretics, four were due to nonsteroidal anti-inflammatory drugs, three were due to angiotensin-converting enzyme inhibitors, and one was from the use of contrast medium. The 41 patients with iatrogenic-related renal disease were older than the other 59 patients (61.8 vs 49.3 years). Iatrogenic renal disease developed in 1% of all patients admitted to a tertiary care hospital, and 12% of these patients died. The most common renal syndrome is acute renal failure, most often caused by nephrotoxic drugs. The incidence can probably be decreased by better monitoring of body weight and fluid balance to prevent dehydration and by the avoidance of nephrotoxic drugs.

Acute Kidney Injury↗
PubMed1989

Encephalomyelitis and myositis in a boxer puppy due to a Neospora-like infection.

A 10-week-old Boxer dog from Uppsala, Sweden, was killed because of hind limb paralysis. The hind limb muscles were grossly atrophied and encephalomyelitis and myositis were the predominant microscopic lesions. Neospora caninum-like tachyzoites were found in the brain and skeletal muscles, and tissue cysts were found in the brain. The organism was not Toxoplasma gondii, as T. gondii antibody was not found in the indirect fluorescent antibody test in serum samples from the puppy and the dam, and the organism in the dog's brain did not react with T. gondii antibody in the immunoperoxidase test.

Animals↗
PubMed1988

Serum antibody response to canine parvovirus, canine adenovirus-1, and canine distemper virus in dogs with known status of immunization: study of dogs in Sweden.

Serum antibody titers to canine parvovirus (CPV), canine adenovirus-1 (CAV-1), and canine distemper virus (CDV) were measured in dogs with known immunization status. The dogs represented 3 groups: nonvaccinated dogs less than 12 months old; vaccinated dogs less than 12 months old; and adult dogs greater than 12 months old. For practical reasons, the population from which the specimens were obtained could be considered as free from natural infection with CAV-1 and CDV. In nonvaccinated dogs less than 12 months old, antibodies against all 3 viruses were measured at the time the dogs were given their first vaccination. Altogether, 50.7% of the dogs had titer greater than or equal to 1:10 to CPV, and 26.1 and 46.2% had titer greater than or equal to 1:8 to CAV-1 and CDV, respectively. The concentration of maternal antibody seemed to be of major importance for failure of immunization with use of inactivated CPV vaccine, but not with CAV-1 and CDV vaccination. In dogs less than 12 months old and vaccinated against CPV infection with inactivated virus, only 11.5% had titer greater than or equal to 1:80. In dogs vaccinated against infectious canine hepatitis and canine distemper, 63.2 and 78.3%, respectively, had titer greater than or equal to 1:16. In adult dogs greater than 2 months old and vaccinated against CPV infection, less than 50% had titer greater than or equal to 1:80, regardless of time after vaccination. There was no significant difference in titer between vaccinated and nonvaccinated dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoviridae↗
PubMed1987

Campylobacter in the dog: a clinical and experimental study.

Faecal samples from 54 dogs with diarrhoea and 54 control dogs were cultured for Campylobacter, Salmonella and Yersinia species and controlled for enteric viruses. The campylobacter were identified as either C jejuni/coli or C upsaliensis. In the diarrhoeic group 16 dogs (29.6 per cent) were positive for campylobacter, 10 C upsaliensis and six C jejuni/coli. Concomitant infection with parvovirus was evident in six of the dogs with diarrhoea and campylobacter-positive faecal cultures. In the control group 13 dogs (24.1 per cent) were positive for campylobacter; three of the isolates were C upsaliensis and six C jejuni/coli. Four isolates could not be identified. The most prominent clinical findings in naturally occurring cases were an acute onset of vomiting (12 of 16), diarrhoea (16 of 16) which was often haemorrhagic (nine of 16) and a raised rectal temperature. Dogs were infected experimentally with both C jejuni (three dogs) and C upsaliensis (three dogs). The challenge strains could be identified in faecal samples from all the dogs, but clinical signs of diarrhoea were seen in only one dog infected with C jejuni. Soft faeces was passed by one dog infected with C upsaliensis. It is concluded that C jejuni/coli or C upsaliensis are either primary pathogens or, after predisposing factors such as virus infections, act as secondary pathogens. It also seems probable that Campylobacter species are present in the intestinal flora of the normal dog.

Animals↗
PubMed1986

Transformations of arylpropane lignin model compounds by a lignin peroxidase of the white-rot fungus Phanerochaete chrysosporium.

Various lignin model compounds of the O-arylpropane type were oxidized with purified lignin peroxidase from the white-rot fungus Phanerochaete chrysosporium, and oxidation products were identified by gas-chromatography/mass-spectroscopy procedures. Our results are in accord with the theory that lignin peroxidase catalyzes one-electron oxidations of its substrates with formation of cation radicals, and that these radicals undergo degradative reactions that are predictable from a knowledge of cation radical and oxygen chemistry. Cation radicals formed from O-arylpropane model compounds appeared to undergo the following types of degradative transformations: addition of water to ring-centered radicals, followed by proton loss yielding quinones and alcohols; nucleophilic attack by hydroxy functions on propanoid moieties giving cyclic ketals as intermediates which decompose to yield side chain migration products; transfer of the charge of a radical from a ring to the associated alkyl moiety through an ether bond, with loss of a proton from the latter, forming a new carbon-centered radical. The new alkyl-centered radicals apparently were able to abduct dioxygen to form peroxyl radicals which decomposed giving a variety of oxidation products and probably superoxide anion. Specific examples of the above transformations are presented, and their relevance to lignin degradation is discussed.

Basidiomycota↗
PubMed1985

Enterotoxigenic Escherichia coli (ETEC) and Klebsiella pneumoniae isolated from dogs with diarrhoea.

Faecal samples from 148 dogs with diarrhoea and from 15 healthy dogs were cultured for bacterial pathogens with enterotoxigenic properties. The aim of the study was to define the toxin profile (production of heat-labile [LT] and heat-stable [ST] toxins) and possible surface fimbrial antigens. Enterotoxigenic bacteria were isolated from 6 (4.1%) dogs with diarrhoea, four of these were Escherichia coli and two were Klebsiella pneumoniae. The E. coli strains and K. pneumoniae strains were producing both LT and ST toxins. The LT toxin from these strains was not neutralized by human anti-LT serum or anti-choleragen and did not cause coagglutination with Staphylococcus aureus coated with anti-human-LT. This suggests that the LT toxin produced by these canine isolates is non-identical to LT toxin from human strains. Three of the ETEC strains were haemagglutinating and showed surface hydrophobic properties. Electron microscopy showed that canine ETEC isolates possessed fimbriae of two different types: thick (5-5.5 nm) and thin (2-3 nm).

Animals↗
PubMed1982

Evaluation of a killed feline panleukopenia virus vaccine against canine parvoviral enteritis in dogs.

Immunogenic potency of a killed feline panleukopenia virus vaccine against canine parvoviral enteritis in dogs was examined. The vaccine elicited hemagglutination-inhibition antibodies to canine parvovirus (CPV) in all of the 72 dogs which were vaccinated. The vaccine was protective in dogs against both experimentally induced and naturally occurring CPV-induced disease. By statistical analysis, 4 weeks was found to be the optimal spacing between 2 vaccinal doses resulting in hemagglutination-inhibition antibody titers up to 1:5,120. Adverse reactions to the vaccine were not observed. Atypical lymphocytes were found consistently in the CPV-infected control dogs.

Animals↗