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Biomedical subjects

J M Kelly

Publications and source records attributed to J M Kelly.

At least 163 records · Page 9Linked to original sources
PubMed1985

A comparative study of the interaction of 5,10,15,20-tetrakis (N-methylpyridinium-4-yl)porphyrin and its zinc complex with DNA using fluorescence spectroscopy and topoisomerisation.

Binding of 5,10,15,20-tetrakis (N-methylpyridinium-4-yl)porphyrin (H2TMPyP4+) and its zinc complex (ZnTMPyP4+) to DNA is demonstrated by their coelectrophoresis and by absorption and fluorescence spectroscopic methods. Topoisomerisation of pBR322 DNA shows that H2TMPyP4+ unwinds DNA as efficiently as ethidium bromide showing that it intercalates at many sites. ZnTMPyP4+ may cause limited unwinding. Marked changes in the fluorescence spectra of the porphyrins are found in the presence of DNA. The fluorescence intensity of either H2TMPyP4+ or ZnTMPyP4+ is enhanced in the presence of poly (d(A-T)), whereas in the presence of poly (d(G-C] the fluorescence intensity of ZnTMPyP4+ is only slightly affected and that of H2TMPyP4+ markedly reduced. Both the porphyrins photosensitize the cleavage of DNA in aerated solution upon visible light irradiation.

Animals↗
PubMed1985

Transformation of Aspergillus niger by the amdS gene of Aspergillus nidulans.

Aspergillus niger grows poorly on acetamide as a nitrogen or carbon source and lacks sequences detectably homologous to the amdS gene encoding the acetamidase of Aspergillus nidulans. We have taken advantage of these observations to develop a transformation system for A. niger using the amdS gene as a dominant heterologous marker for selecting transformants on the basis of acetamide utilization. Transformants varied in their ability to grow on amide media and the number of integrated copies of the amdS plasmid ranged from 1 or 2 to greater than 100. Southern analysis of transformants revealed that the multiple copies were integrated into the chromosome in tandem arrays. This result indicates that transformation of A. niger is more similar to mammalian cells than to yeast. Analysis of enzyme activity levels and RNA levels showed that most of the copies of amdS were expressed. Mitotic stabilities of transformants were found to be high. A transformant containing greater than 100 copies of the amdS gene was impaired in omega-amino acid utilization, a result that has also been found in A. nidulans. Since, in A. nidulans, omega-amino acids induce acetamidase via a characterizied regulatory gene (amdR/intA) this observation implies that titration of an analogous A. niger regulatory gene product by multiple amdS copies has occurred. Additional evidence suggested that the amdS gene is regulated in A. niger. It has also been shown that an unselected plasmid can be co-transformed with the amdS plasmid into A. niger.

Amidohydrolases↗
PubMed1984

Induction of human mRNAs by interferon.

We have cloned a set of seven cDNAs corresponding to mRNAs induced by type I interferon in human cells, and are using these probes to characterize the response to interferon in detail. We have studied the kinetics of induction of each mRNA in three different human cell lines, the sensitivity of induction to cycloheximide, the effect of withdrawing interferon and the response of a receptor-positive interferon-resistant cell line.

Cell Line↗
PubMed1983

Structure-function studies on phytochrome. Preliminary characterization of highly purified phytochrome from Avena sativa enriched in the 124-kilodalton species.

A new protocol for the purification of phytochrome from etiolated Avena sativa L. seedlings in 15-25% yield is described. This preparation exhibits molecular properties dissimilar to those previously reported from oats. Phytochrome prepared by this method contains a dominant species having a Mr = 124,000 (70% of total) on sodium dodecyl sulfate-polyacrylamide gels, in addition to a chromoprotein species with Mr = 118,000 (30%). A blocked NH2 terminus is indicated by amino acid sequencing of the purified chromoprotein preparation. By ultraviolet-visible spectroscopy, this preparation displays a 730-nm absorption maximum for Pfr, an enhanced APfr730/APfr668 ratio under saturating red light illumination, and a reduced amount of dark reversion. Circular dichroism reveals a new absorption band for Pfr in the blue spectral region. These spectral properties and electrophoretic behavior are consistent with available information on phytochrome in vivo or in rapidly prepared extracts from oat seedlings. Thus, the molecular properties described here may more accurately reflect those of phytochrome in vivo in etiolated A. sativa shoots than those of phytochrome species isolated by previous methodologies.

Edible Grain↗
PubMed1983

Incidence of lameness in dairy cows.

A survey of the number of treatments for lameness in 21,000 dairy cows from 185 herds in the University of Edinburgh/Dalgety Spillers dairy herd health and productivity service in England and Wales showed an average incidence of cases of 25 per cent. Veterinary surgeons treated 6.3 per cent and farmers 18.7 per cent and 1.4 per cent of cows were culled because of lameness. Monthly and regional variations were recorded. An assessment of the economic effects suggested that the average annual cost in a 100 cow herd was 1175 pounds with an overall cost to British farmers of more than 35 million pounds. The economic importance is such that research into specific factors affecting foot health should be carried out. Meanwhile, a broad approach to prevention and control of lameness on farms is recommended under the general headings of management/environment, nutrition and breeding.

Animal Nutritional Physiological Phenomena↗
PubMed1983

A study of combined arm and leg exercise with application to nordic skiing.

A laboratory test was developed to study the metabolic and gas exchange effects of arm, leg and combined arm and leg work. The test incorporated movement patterns similar to those used in cross-country skiing. The work rate for the arm test at maximal effort was 33% (125 watts) and the leg test was 81% (302 watts) of that for the combined test (375 watts). The maximum oxygen uptake (VO2 max) was not significantly different when comparing the leg test to the combined test, but VO2 at submaximal work levels was significantly less during the combined test. The anaerobic threshold (AT) occurred at 68, 73 and 76% of VO2 max for the arm, leg, and combined test, respectively. Although there were no significant differences in VO2 and percent of VO2 max, at the AT between the leg test and the combined test, AT was significantly delayed with respect to time and work rate in the latter condition. Application of these results to cross-country skiing supports the proposal for greater upper body involvement in skiing.

Arm↗
PubMed1982

The nucleotide sequence at the 3'-end of Neurospora crassa 18S-rRNA and studies on the interaction with 5S-rRNA.

The sequence of more than 100 nucleotides at the 3'-end of Neurospora crassa 18S-rRNA was determined by chemical sequencing techniques. Extensive homologies with 18S-rRNA from other eukaryotes were found. Inspection of the nucleotide sequence at the 3'-end of N. crassa 5S-rRNA revealed the presence of sequences complementary to a region near the 3'-terminus of 18S-rRNA. Under the appropriate conditions a complex was formed between 18S-rRNA and 5S-rRNA (Tm 53 degrees C). Interaction was detected between 5S-rRNA and a specific 3'-terminal fragment from 18S-rRNA and between 18S-rRNA and a specific 3'-terminal fragment from 5S-rRNA. These findings are consistent with the idea that intermolecular base-pairing between nucleotides at the 3'-ends of 18S-rRNA and 5S-rRNA may be functionally important within the ribosome. Further investigation revealed that this intermolecular base-pairing is not essential for ribosome stability.

Animals↗
PubMed1982

Periodicity in the length of 3'-poly(A) tails from native globin mRNA of rabbit.

Globin mRNA from rabbit reticulocytes was labelled at the 3'-end with [5'-32P]pCp by T4 RNA ligase. The 3'-poly(A) tail was released by digestion of mRNA with T1 ribonuclease and its size distribution determined by gel electrophoresis and autoradiography. The length of the 3'-poly(A) tails varied from about 15-150 residues, but the size distribution exhibited peaks in the abundance of poly(A) species at intervals of approx. 25 residues. This periodicity appears to reflect the manner in which proteins bind to the 3'-poly(A) tail. The function of such regular interactions may be to control mRNA breakdown in the cytoplasm.

Animals↗
PubMed1982

Local recurrence after low anterior resection using the staple gun.

Eleven early anastomotic recurrences have occurred after 34 low anterior resections for carcinoma of the rectum performed during the past 2 years using the EEA staple gun. These recurrences all occurred after resection of locally advanced tumours and caused distressing symptoms, and it is suggested that this technique might be best reserved for more favourable growths.

Aged↗
PubMed1982

The regulation of NADP-linked isocitrate dehydrogenase in Aspergillus nidulans.

The regulation of NADP-linked isocitrate dehydrogenase (NADP-IDH) has been studied in wild-type and mutant strains of Aspergillus nidulans. In the wild-type strain studied, the levels of NADP-IDH vary in a similar way to those of acetamidase, acetyl-CoA synthase, isocitrate lyase and malate synthase under all growth conditions used. Similarly, fac mutants, which are altered in the regulation of these enzymes of acetate utilization, are affected in NADP-IDH levels in a parallel fashion, as are cre mutants, which show altered carbon catabolite repression of this group of enzymes. Possible functions of the NADP-IDH enzyme are considered.

Acetate-CoA Ligase↗