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Biomedical subjects

T M Murphy

Publications and source records attributed to T M Murphy.

At least 73 records · Page 4Linked to original sources
PubMed1983

Distribution of mutants in aggregates of cultured cells.

The analysis of the distribution of mutants in an exponentially growing culture of cells that are aggregated into clumps of homogeneous size is described, given the mutation rate and a random process by which clumps divide to produce progeny. The mean and standard deviation of the proportion of clumps with a given number of mutant cells at a particular time are calculated. Since the standard deviation tends to be much smaller than the mean, the following conclusions can be drawn. Aggregation lowers the number of mutant-containing clumps in cultures grown to a standard number of cells, but raises the number of mutant-containing clumps in cultures grown to a standard number of clumps. In the absence of mutation, or at low mutation rates, clumps tend to become pure types (normal or mutant). The probability of finding pure, nonmutant-containing clumps, however, is approximately the initial fraction of nonmutant cells (given realistic forward and back mutation rates). Also, in terms of the given process, it is possible to compute the probability that all the cells in an aggregate descend from a single, common parent cell within a given number of generations, and thus to calculate the probability that all the cells in a clone grown from an aggregate descend from a single cell within a known number of generations.

Cell Aggregation↗
PubMed1983

Trigger point injections vs. jet injection in the treatment of myofascial pain.

Trigger point injections using dilute solutions of local anesthetic agents have proved effective for many patients with myofascial pain. The treatment itself, however, can produce severe pain and may occasionally be associated with complications. It was determined in this study that a local anesthetic solution administered by jet injection in the area of myofascial trigger points was capable of providing short-term pain relief equal to conventional trigger point injections using a hypodermic needle and syringe. The jet injector system produced significantly less pain during treatment than conventional trigger point injections and therefore was preferred by most subjects having the opportunity to compare both forms of treatment.

Adult↗
PubMed1983

Ultraviolet-Stimulated KHCO(3) Efflux from Rose Cells: Regulation of Cytoplasmic pH.

Suspension-cultured cells of Rosa damascena that have been irradiated with ultraviolet light (254 nanometers, 2.1 x 10(4) joules per square meter) rapidly lose K(+) and HCO(3) (-) ions to the medium. If the HCO(3) (-) is derived from respiratory CO(2) inside the cell, then loss of HCO(3) (-) should be accompanied by an acidification of the cytoplasm. Estimates of the pH of control and ultraviolet-irradiated cells by (31)P-nuclear magnetic resonance spectroscopy indicated that, following irradiation, the pH of both cytoplasm and vacuole dropped by 0.2 to 0.3 units. This change was not as great as was predicted from the observed HCO(3) (-) loss. Analysis of nitrogenous compounds in the cell suggested that reduction of nitrate and synthesis of gamma-aminobutyric acid absorbed some of the protons formed by the synthesis and dissociation of bicarbonate.

Journal Article↗
PubMed1982

Dose requirement of local anaesthetic to produce grand mal seizure during stellate ganglion block.

Two case reports illustrate that low doses of local anaesthetics such as bupivacaine 2.5 mg and a mixture of bupivacaine 1.25 mg and lidocaine 5 mg can induce grand mal seizures if injected into the vertebral artery during stellate ganglion block. The effect of the dose of local anaesthetic agent and technique of administration into the stellate ganglion region discussed as is the relationship between vertebral artery blood flow and cerebral intravascular local anaesthetic concentration required to produce seizure activity. Suggestions are made concerning possible modification of the technique of anterior approach to the stellate ganglion, including test dose size, to reduce the incidence of inadvertent injection into the vertebral artery and subsequent central nervous system toxicity.

Adult↗
PubMed1982

UV-Stimulated K Efflux from Rose Cells: Counterion and Inhibitor Studies.

Irradiation of a washed suspension of cultured rose (Rosa damascena var. Gloire de Guilan) cells with about 1,680 joules per square meter of short wave ultraviolet (UV) light (254 nanometers) caused K(+) to appear in the external medium. Short-term tracer ((86)Rb(+)) experiments confirmed the earlier suggestion (Wright, Murphy 1978 Plant Physiol 61: 434-436) that UV increases the efflux of K(+); there was also a small decrease in influx of K(+). There was a partial recovery of fluxes from the effects of UV radiation, but no net accumulation of K(+) within 16 to 18 hours after the irradiation. The K(+) appearing in the medium was matched by an equivalent amount of HCO(3) (-); it was suggested that HCO(3) (-) was the principal counterion for the K(+) flux induced by UV. Inhibitors of ATP synthesis (10(-5) molar carbonyl cyanide m-chlorophenyl hydrazone; 0.05 millimolar KCN plus 0.75 millimolar salicylhydroxamic acid) strongly reduced the UV-stimulated K(+) leakage, suggesting that the leakage was dependent in some way on ATP concentration inside the cells. The UV-induced K(+) leakage was also dependent on temperature and the presence of Ca(2+) in the external medium.

Journal Article↗
PubMed1981

Induction and Characterization of Chlorate-resistant Strains of Rosa damascena Cultured Cells.

The sensitivity of Rosa damascena cultured cells to chlorate was measured by plating samples of suspensions in agar containing NaClO(3). This sensitivity depended on the age of the cultures that were plated. Chlorate-resistant colonies isolated from 5- to 7-day cultures retained their resistance through many generations of growth in medium lacking NaClO(3); they also retained resistance when mixed with sensitive cells. Treating cell aggregates with ultraviolet (UV) light (254 nanometers), or UV light (360 nanometers) in the presence of 4'-methoxymethyltrioxsalen, increased the proportion that was resistant to NaClO(3). However, the amount of increase was low (three times) and required very specific doses of UV light. The UV treatments did not select for chlorate-resistant cells over chlorate-sensitive cells. The data suggested that UV had induced mutations leading to chlorate resistance. Approximately 15% of the resistant strains did not grow on medium containing nitrate as the sole nitrogen source. These strains lacked ability to reduce chlorate to chlorite. This observation supports the current idea that chlorate toxicity depends on the activity of nitrate reductase. Approximately 85% of the resistant strains grew on medium containing nitrate as the sole nitrogen source. These strains lost catalase activity following chlorate treatment, indicating that they took up and reduced chlorate. These strains have a mechanism for tolerating chlorate and its reduction products, rather than avoiding them.

Journal Article↗
PubMed1979

A Strain of Rosa damascena Cultured Cells Resistant to Ultraviolet Light.

A strain of cultured cells of Rosa damascena Mill. which showed unusual resistance to damage by short wave (254 nanometers) ultraviolet radiation was isolated. The resistant cells were 2.2 to 2.8 times larger and had about twice the amount of DNA and more chromosomes than the parental, sensitive cells. The resistant cells also produced larger quantities of polyphenolic compounds, principally flavonoids, during the later phases of culture growth. At 10 days, resistant cells had 4 times more nonflavonoid polyphenolics and 14 times more flavonoids than parental cells. The resistance, which was also observed only in the later phases of culture growth, was best correlated with the production of polyphenolics, which apparently shielded ultraviolet-sensitive target molecules from damage.

Journal Article↗
PubMed1979

Blockade of the pressor response to muscle ischemia by sensory nerve block in man.

Differential nerve block from peridural anesthesia was used to determine a) if the pressor response to muscle ischemia in man is caused by stimulation of small sensory nerve fibers and b) if these fibers contribute to cardiovascular-respiratory responses during dynamic exercise. Four men exercised at 50-100 W for 5 min. Muscle ischemia and a sustained pressor response were produced by total circulatory occlusion of both legs beginning 30 s before the end of exercise and continuing for 3 min postexercise. During regression of full motor and sensory block, motor strength recovered while sensory block continued; the pressor response was blocked as long as sensory anesthesia persisted (two subjects). During blockade of the pressor response, cardiovascular-respiratory responses to exercise gradually returned from augmented to normal (preblock) levels. Sensory blockade was incomplete in two subjects and the pressor response was not fully blocked. We conclude that stimulation of small sensory fibers during ischemia elicits the pressor response, but that these fibers appear not to contribute to cardiovascular-respiratory responses during mild dynamic exercise with adequate blood flow.

Adult↗
PubMed1979

Cardiovascular and subjective central nervous system effects of long-acting local anaesthetics in man.

Intravenous infusions of etiodocaine 50, 75 and 100 mg and bupivacaine 75 mg were carried out over ten minutes in healthy young adult males. Cardiovascular sequelae were generally trivial at all doses. A collection of subjective central nervous system symptoms were described which may be regarded as early warning of impending local anaesthetic toxicity. Plasma concentrations of etidocaine were proportional to dose and ranged from 2 micrograms/ml to 5 micrograms/ml at the termination of the infusion. Plasma concentrations of bupivacaine were similar to those from the same dose of etidocaine but declined more slowly on cessation of infusion.

Acetanilides↗
PubMed1978

Pseudomonas colonization in cystic fibrosis. A study of 160 patients.

We investigated the role of Pseudomonas aeruginosa colonization in the respiratory tracts of cystic fibrosis (CF) patients to relate the effect of this colonization to progression of bronchial airway pathologic conditions and to the patients' clinical progress, and to identify predisposing factors to persistence of P aeruginosa colonization and bronchial tree damage. Half of 160 CF patients studied had persistent P aeruginosa respiratory tract colonization; the other half had none. Pseudomonas aeruginosa seems to have an exclusive propensity for the respiratory tract and may appear at any age. Treatment with antibiotics, including aminoglycosides, failed to eradicate P aeruginosa. The continuous use of antibiotics seemed to contribute to the persistence of P aeruginosa and the appearance of mucoid strains of P aeruginosa.

Adolescent↗
PubMed1978

The parasite fauna of the American alligator (Alligator mississippiensis) in South Carolina.

Twelve American alligators (Alligator mississippiensis) were obtained from three different areas of South Carolina. One species of pentastome (Sebekia oxycephala), two species of nematodes (Dujardinascaris waltoni and Multicaecum tenuicolle), four species of trematodes (Polycotyle ornata, Acanthostomum coronarium, Archaeodiplostomum acetabulatum and Pseudocrocodilicola americaniense) and one species of hemogregarine (Haemogregarina crocodilnorum) were recovered. Polycotyle ornata was observed only in alligators from Par Pond while P. americaniense was found in Par Pond and coastal hosts, A. acetabulatum from Kiawah Island and coastal alligators, and A. coronarium only at Kiawah Island. These patterns suggest disjunct distributions for the trematode species in South Carolina alligators. The other parasites were found in alligators from all three locations. The only parasite observed to initiate damage or lesions in the alligator was the pentastome.

Alligators and Crocodiles↗
PubMed1977

Acupuncture analgesia and anesthesia.

After the war of liberation, Mao Tse Tung encouraged an integration of Western and traditional Chinese medicine. Several schools of therapeutic acupuncture have defined different points of puncture, originally assumed to be on an empiric basis but now rationalized as areas where nerve endings congregate. Results of therapeutic acupuncture in China cannog be evaluated because of inadequate record keeping. At the University of Washington Pain Clinic, immediate results (two to three days) are good but never lasting, nor do they decrease concomitant medication. For anesthesia, acupuncture acts to produce only hypalgesia in most patients, although some experience total analgesia. Patient selection and mental preparation are careful. Hence, the method is used in much less than 10% of the operations in China, and in these the analgesia is satisfactory by Western standards in only approximately 30%. Concepts as to the mode of action of acupuncture analgesia range from an attitudinal change towards sensory input to the release of a neurohumoral analgesic substances.

Acupuncture Therapy↗