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Biomedical subjects

J H Taylor

Publications and source records attributed to J H Taylor.

At least 37 records · Page 2Linked to original sources
PubMed1992

Tiletamine hydrochloride in combination with zolazepam hydrochloride as an anaesthetic agent in sheep.

The anaesthetic effects of Zoletil, a 1:1 combination of tiletamine and zolazepam, was evaluated in 10 sheep. The optimum dose of this preparation was found to be 12 mg kg-1. It produced rapid induction, cataleptoid anaesthesia and smooth recovery with a minimal effect on blood pressure. Individual sheep, however, displayed variable reactions to the anaesthetic. Atropine premedication at 0.04 mg kg-1 did not have any significant effect on either heart rate or blood pressure when compared to Zoletil alone.

Anesthetics↗
PubMed1991

Experimental brain hyperthermia: techniques for heat delivery and thermometry.

An experimental canine brain model was developed to assess the effects of hyperthermia for a range of time and temperature endpoints, delivered within a specified distance of an interstitial microwave antenna in normal brain. The target temperature location was defined radially at 5.0 or 7.5 mm from the microwave source at the longitudinal location of maximum heating along the antenna in the left cerebral cortex. Temperatures were measured with fiberoptic probes in a coronal plane at this location in an orthogonal catheter at 1.0 mm intervals. Six antennas were evaluated, including dipole, modified dipole, and four shorted helical antennas with coil lengths from 0.5 to 3.9 cm. Antenna performance evaluated in tissue equivalent phantom by adjusting frequency at a fixed insertion depth of 7.8 cm or adjusting insertion depth at 915 MHz showed dipoles to be much more sensitive to insertion depth and frequency change than helical antennas. Specific absorption rate (SAR) was measured in a brain/skull phantom and isoSAR contours were plotted. In vivo temperature studies were also used to evaluate antenna performance in large and small canine brain tissues. A helical antenna with a 2.0 cm coil length driven at 915 MHz was chosen for the beagle experiments because of tip heating characteristics, well-localized heating along the coil length, and heating pattern appropriate to the smaller beagle cranial vault. Verification of lesion dimensions in 3-D was obtained by orthogonal MRI scans and histology to document the desired heat effect, which was to obtain an imagable lesion with well-defined blood-brain-barrier breakdown and necrotic zones. The desired lesion size was between 1.5 to 2.5 cm diameter radially, in the coronal plane with the greatest diameter.

Animals↗
PubMed1991

The effect of endogenously produced carbon monoxide on the oxygen status of dogs infected with Babesia canis.

Carboxyhaemoglobin fractions were found to be significantly higher (P less than 0.05) in dogs (n = 5) with severe babesiosis than in control subjects (n = 5). The enzymatic conversion of haem to biliverdin by haem oxygenase is the only known source of endogenous carbon monoxide. We propose that the increased production of endogenous carbon monoxide following the haemolysis associated with babesiosis, results in the carboxyhaemoglobinaemia observed in this study. The superimposition of carboxyhaemoglobinaemia on severe anaemia results in further compromise of the oxygen status of dogs with severe babesiosis, and probably plays a role in the pathogenesis of the hypoxic tissue damage associated with this condition.

Animals↗
PubMed1990

Chromosome reproduction: units of DNA for segregation.

Evidence is summarized which indicates that the DNA loop anchoring proteins in chromosomes are effectively heterodimers that stack and are fastened into a bilaterally symmetrical array along the chromonemal axis. The evidence consists primarily of the observations made twenty five to thirty years ago on the pattern of sister chromatid exchanges and the way the DNA chains are sorted in the formation of diplochromosomes in cells that have undergone endoreduplication. The evidence indicates that each chain of DNA in the single duplex, which is assumed to run the length of a chromosome, is anchored to a bilaterally symmetrical axis of heterodimers that sort the two original chains among the four derived chromatids of each diplochromosome in a very precise way. These observations are considered in the context of investigations on the nature of scaffold proteins and the loop anchorage sequences, as well as the advances being made on the nature of DNA binding proteins and the roles of topoisomerase II.

Animals↗
PubMed1988

Property taxation of a not-for-profit hospital: a case study.

The city of Burlington, Vermont assessed a $2.83 million property tax against the Medical Center Hospital of Vermont, a not-for-profit teaching hospital. The hospital responded by challenging the action in a civil court suit. The city argued that the hospital had ceased to be a charitable institution as the term was used in state statutes. The Vermont Superior Court found for the hospital, over-turning the assessment by the city and prohibiting collection of the tax. The court held that the hospital retained its charitable nature in spite of changes in the organization and the health care environment. The holding in the case provides one more view in the continuing national debate over the function and future of charitable hospitals.

Charities↗
PubMed1987

Sequence organization and developmentally regulated transcription of a family of repetitive DNA sequences of Xenopus laevis.

Members of a family of DNA sequences of Xenopus laevis have been cloned and sequenced. Molecular analyses revealed that these sequences are moderately repetitive and dispersed throughout the genome. The sequences of seven clones were compared. Two of the clones lie in the globin gene cluster; one 5' to the adult alpha 1 gene, and the other in the first intron of the tadpole alpha 1 gene. In all clones, the homologous region begins at the same site, but the lengths of the common regions vary from 123 bp to over 320 bp due to heterogeneous 3' ends. Some of the repeats are bracketed by direct and/or inverted repeats, and relatively large palindromes were found 5' to the common region in some clones. These characteristics, and the presence of a repeat 5' to one of a pair of duplicated alpha genes suggests that some family members may be capable of transposition. A number of interesting features were found in the sequences, including multiple elements similar to the yeast autonomously replicating sequence, and a sequence which is about 80% homologous to the first 30 bases of the SV40 enhancer. Transcription studies revealed that homologous transcripts are detectable beginning at neurulation, increase in concentration up to stage 45, and disappear by metamorphosis. Implications of these data are discussed.

Aging↗
PubMed1986

Late postpoliomyelitis muscular atrophy: a case report and clinical discussion.

Late postpoliomyelitis muscular atrophy (PPMA), a condition afflicting those who contracted poliomyelitis before the discovery of the vaccines in the 1950s, is a pathology that has only recently been described. A brief case report of a late PPMA patient is followed by a discussion of the etiology of the condition. Diagnostic and differential diagnostic considerations are presented, along with treatment goals and treatment paradigms.

Adult↗
PubMed1985

One role for DNA methylation in vertebrate cells is strand discrimination in mismatch repair.

Although the occurrence of 5-methylcytosine (m5C) in DNA is widespread, the function of this modified base remains unclear. At some specific sites it apparently has an effect in controlling gene expression, but many sites do not appear to be involved in this regulation. Balanced against its regulatory usefulness at some sites is the mutational risk it imposes upon the cell. Deamination of m5C can lead to its replacement by thymine (T). One possible role for excess methylation is strand discrimination in the repair of mismatches. We constructed the complementary hemimethylated single-base-pair mismatches, G T and A C, at a CG site in simian virus 40 DNA, transfected these into the host African green monkey kidney cells (CV-1), and examined DNA of the progeny for repair at this site. Hemimethylation at two Hha I sites (Gm5CGC) bracketing the mismatch directed repair to occur only on the unmethylated strand. Methylation at the multiple Cm5CATGG and Gm6ATC sites, a pattern normally seen in bacteria, also instructed repair to proceed on the unmethylated strand, although less efficiently. Hemimethylation at only one site, adjacent to the mispaired bases (Hpa II, Cm5CGG) produced repaired molecules in a ratio that may represent random repair of the A C mismatch and strand-directed repair in the complementary G T mismatch. The -mCG- -GT- mismatch could result from deamination of m5C in the most commonly methylated dinucleotide in vertebrates, CpG. Methylation may be able to compensate for the errors it causes by serving as a mechanism for strand discrimination in correcting those errors. In addition, single-strand nicks were also shown to direct repair.

5-Methylcytosine↗