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Biomedical subjects

T Kavanagh

Publications and source records attributed to T Kavanagh.

At least 19 recordsLinked to original sources
PubMed1992

Molecular analysis of a resistance-breaking strain of potato virus X.

Full-length cDNA clones of potato virus X (PVX) strains PVXUK3 and PVXHB have been constructed in plasmid vectors to allow in vitro transcription of infectious PVX RNA. In both instances the transcript-derived virus infected tobacco and potato identically to the respective progenitor strains: in tobacco and susceptible potato cultivars both strains infected systemically, producing symptomless or mild mosaic symptoms. In potato carrying the Rx or Nx resistance genes, the virus derived from the PVXHB cDNA infected systemically, whereas the virus derived from the PVXUK3 cDNA failed to infect the Rx plants or induced apical necrosis, characteristic of a hypersensitive response of the Nx gene. Three hybrid viral genomes were constructed at the cDNA level to localize the resistance breaking determinants of PVXHB. Transcripts of all three hybrids were infectious on tobacco. On potato cultivars with either the Rx or Nx resistance genes, the hybrid viruses infected in the same way as PVXHB, rather than PVXUK3. The common feature of these hybrid viruses, the coat protein gene, is therefore the determinant of Nx and Rx resistance breaking of PVXHB.

Amino Acid Sequence↗
PubMed1992

Potato virus X as a vector for gene expression in plants.

The suitability of potato virus X (PVX) as a gene vector in plants was tested by analysis of two viral constructs. In the first, the GUS gene of Escherichia coli was substituted for the viral coat protein gene. In the second, GUS was added into the viral genome coupled to a duplicated copy of the viral promoter for the coat protein mRNA. The viral construct with the substituted coat protein gene accumulated poorly in inoculated protoplasts and failed to spread from the site of infection in plants. These results suggest a role for the viral coat protein in key stages of the viral infection cycle and show that gene replacement constructs are not suitable for the production of PVX-based gene vector. The construct with GUS coupled to the duplicated promoter for coat protein mRNA also accumulated less well in protoplasts than the unmodified PVX, but did infect systemically and directed high level synthesis of GUS in inoculated and systemically infected tissue. Although there was some genome instability in the PVX construct, much of the viral RNA in the systemically infected tissue had retained the foreign gene insertion, especially in infected Nicotiana clevelandii plants. These data point to a general utility of PVX as a vector for unregulated gene expression in plants.

Base Sequence↗
PubMed1992

Exercise training in patients after heart transplantation.

The post-cardiac transplantation patient is frequently debilitated as a result of "end-stage" heart disease and typically demonstrates muscle wasting, with a reduced work capacity, maximum heart rate and peak oxygen uptake. At submaximal effort, perceived exertion and ventilation are higher, and the absolute ventilatory threshold lower, than in normals. A number of published studies have now shown that an exercise rehabilitation programme can induce a good training effect, although possibly not complete restoration of physiological function. The prescription of exercise must take into account the denervated heart's peculiar response to effort, and rely more on perceived exertion and metabolic measurements for defining intensity of training rather than target training heart rates. Changes in mood and personality have also been noted in these patients, and while these may improve spontaneously with the passage of time, there is some evidence that a rehabilitation programme can help in this regard.

Adult↗
PubMed1991

Exercise training in patients after heart transplantation.

The post-cardiac transplantation patient is frequently debilitated as a result of "end-stage" heart disease and typically demonstrates muscle wasting, with a reduced work capacity, maximum heart rate and peak oxygen uptake. At submaximal effort perceived exertion and ventilation are higher, and the absolute ventilatory threshold lower, than in normals. A number of published studies have now shown that an exercise rehabilitation programme can induce a good training effect, although possibly not complete restoration of physiological function. The prescription of exercise must take into account the denervated heart's peculiar response to effort, and rely more on perceived exertion and metabolic measurements for defining intensity of training rather than target training heart rates. Changes in mood and personality have also been noted in these patients, and while these may improve spontaneously with the passage of time, there is some evidence that a rehabilitation programme can help in this regard.

Affect↗
PubMed1988

Assessment of work capacity in patients with ischaemic heart disease: methods and practices.

Analysis of 1150 post-infarct and post-aorto-coronary bypass graft patients referred to the Toronto Rehabilitation Centre revealed that approximately 10% have not returned to work six months after the acute event. White-collar workers are more successful than blue-collar workers in resuming work, as are those medically treated as compared with the surgically treated. The reasons for prolonged unemployment were more frequently non-medical than medical. Detailed assessment is required where there is doubt about the patient's work capacity, or where legislation and/or trade practices demand it. The simplest procedure is an exercise test with energy cost matching. Telemetry during simulated work tasks or while on work stations in the Centre allows more flexibility, with actual observation and telemetry on the job site the only recourse in certain situations.

Canada↗
PubMed1988

Cardiorespiratory responses to exercise training after orthotopic cardiac transplantation.

We have tested the feasibility and effectiveness of a 2 year (average 16 +/- 7 months) walk/jog exercise program on 36 male orthotopic cardiac transplant patients (21 to 57 years old) seen initially 2 to 23 months after surgery. Comparison of initial exercise test results with those in 45 age-matched normal men showed the patients to have a lesser lean body mass (56 +/- 7 vs 63 +/- 8 kg, p less than .001), with a higher resting heart rate (104 +/- 12 vs 77 +/- 14 beats/min, p less than .001) and systolic (138 +/- 16 vs 129 +/- 17 mm Hg, p less than .001) and diastolic (95 +/- 14 vs 84 +/- 10 mm Hg, p less than .001) blood pressures. Peak power output was less than normal (101 +/- 27 vs 219 +/- 41 W, p less than .001), as was peak heart rate (136 +/- 15 vs 176 +/- 13 beats/min, p less than .001), peak oxygen intake (VO2max) (22 +/- 5 vs 34 +/- 6 ml.kg.min-1, p less than .001), and absolute anaerobic threshold (1.18 +/- 0.40 vs 2.04 +/- 0.40 liters.min-1, p less than .001). Peak ventilatory equivalent was higher (48 +/- 9 vs 37 +/- 61.1-1, p less than .001). Cardiac output (Q), as estimated by the CO2 rebreathing method, was slightly above normal at rest (p less than .01), but below normal at two submaximal work rates. The group's average weekly training distance was 24 km, with eight highly compliant patients progressing to 32 km or more weekly. After training, lean tissue increased (+2.4 +/- 3.1 kg, p less than .001), and resting values were reduced for heart rate (-4 +/- 11 beats/min, p less than .05), systolic (-13 +/- 20 mm Hg, p less than .001), and diastolic (-9 +/- 17 mm Hg, p less than .001) blood pressures. There were significant reductions in submaximal values for minute ventilation (VE), ratings of perceived exertion, and diastolic blood pressure at equivalent workloads. Peak values increased for power output (+49 +/- 34 W, p less than .001), VO2max (+4.0 +/- 6.0 ml.kg.min-1, p less than .001), VE (+20 +/- 20 l.min-1, p less than .001), and heart rate (+13 +/- 17 beats/min, p less than .001), and decreased for diastolic blood pressure (-8 +/- 15 mm Hg, p less than .001).(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1986

The structure and transcription start site of a major potato tuber protein gene.

We have isolated recombinant lambda clones containing intact major tuber protein (patatin) genes and flanking sequences from the commercial tetraploid variety Maris Piper. The gene is composed of seven exons and six introns, spread over 4 kb of DNA. Nuclease mapping defined the 5' end of the mRNA approximately 45 bp upstream of the initiation codon. The 5' end of the gene is preceeded by a canonical TATA box sequence. The three known patatin genes encode proteins of nearly identical Mr but very different isoelectric points. The sequence of the gene does not indicate a role for patatin as one of the globulin class of plant storage proteins.

Amino Acid Sequence↗
PubMed1986

Inhibition of gap junctional intercellular communication in human teratocarcinoma cells by organochlorine pesticides.

Inhibition of intercellular communication, as measured by metabolic cooperation between 6-thioguanine-sensitive and 6-thioguanine-resistant Chinese hamster V79 cells, has been previously shown to be correlated with a large variety of known tumor promoters, including some of the organochlorine pesticides. Since further evidence concerning the effects of those known or suspected animal tumor promoters on human cells is needed, three organochlorine pesticides, dieldrin, aldrin, and 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), were tested for their ability to inhibit metabolic cooperation between 6-thioguanine-sensitive (6TGs, HTP3-4) and 6-thioguanine-resistant (6TGr, HTXTG-1) human teratocarcinoma cells. Similar to the effect of the known mouse skin tumor promoter 12-tetradecanoyl phorbol-13-acetate (TPA), all three pesticides inhibited gap junctional intercellular communication within a noncytotoxic dose range. The dose-response curves of these chemicals were similar to those of other known tumor promoters on Chinese hamster V79 cells. In addition, the transfer of [3H]uridine between teratocarcinoma cells in contact was reduced after pesticide treatment.

Aldrin↗
PubMed1977

Sexual activity after myocardial infarction.

Questionnaires on sexual activity were completed by 161 patients attending an exercise-centred rehabilitation program an average of some 3 years after a myocardial infarction. In almost half the group, sexual activity was unchanged or increased compared with the period before the infarction. In the remainder it was reduced; this group included 29 men who had adopted a more passive sexual role and 26 who were now having angina or ventricular premature beats during intercourse. Although the patients with diminished activity could not be distinguished by means of formal personality test, questionnaires completed by their wives suggested that they were less willing to assume responsibility, had increased difficulty in adjusting to life at home and at work and were more neurotic and depressed than those with normal or increased activity. Furthermore, those with decreased sexual activity had a poorer response to training in terms of attendance, final average jogging distance and gains in physiologic status. Since the frequency of angina and ventricular premature beats was less during intercourse than during standard laboratory exercise, it was concluded that normal sexual relations carry no special risk for the average postcoronary patient; indeed, by enhancing self-esteem and encouraging effective participation in an exercise programm, acceptance of normal sexual activity may improve the prognosis.

Blood Pressure↗