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Biomedical subjects

C Mann

Publications and source records attributed to C Mann.

At least 109 records · Page 6Linked to original sources
PubMed1989

Laryngospasm-induced pulmonary edema.

Laryngospasm is one of the more common forms of airway obstruction encountered by an anesthetist. Therapy usually is straightforward, with resolution of the obstruction normally occurring within minutes. In some cases, however, the patient's vigorous inspiratory efforts may lead to a rapidly deteriorating form of pulmonary edema. Two cases are presented that are quite typical of the development of this complication. The etiology, recognition and management of this form of non-cardiac pulmonary edema is discussed.

Adult↗
PubMed1988

The value of indices in the central and peripheral visual fields for the detection of glaucoma.

We assessed 81 patients in four groups (normal, low- and high-risk ocular hypertension, and early glaucoma) with the standard Octopus G1 central visual field program in addition to two quantitative programs, PFN (peripheral field-nasal) and PFT (peripheral field-temporal), designed for this study to test the nasal and temporal periphery, respectively. Indices were calculated for each program for each subject in all groups. We then examined the behavior of the indices across the separate visual field areas within each group as well as the behavior of the indices of each field area among the different groups. We found that quantitative testing of the peripheral nasal visual field provided valuable information in the detection of glaucomatous visual dysfunction additional to that provided by quantitative testing of the central visual field. Quantitative testing of the temporal periphery was less valuable.

Adult↗
PubMed1987

RPC40, a unique gene for a subunit shared between yeast RNA polymerases A and C.

Yeast RNA polymerases A and C share an approximately equal to 40 kd subunit. We have identified, sequenced, and mutagenized in vitro the AC40 subunit gene. The RPC40 gene is unique in the yeast genome and is required for cell viability. This gene contains an open reading frame encoding a 37.6 kd protein having no significant homology with bacterial RNA polymerase subunits. The promoter region contains a 19 bp sequence also present in the largest subunit of RNA polymerase C. It also contains a well-conserved RPG box, a sequence found in the promoter region of many genes encoding the translational apparatus. A novel, plasmid-shuffling method was developed to isolate a large number of RPC40 ts mutants. One of these, ts4, was shown to be defective in the synthesis of RNA polymerases A and C at the restrictive temperature. In contrast, RNA polymerase B was made normally.

Amino Acid Sequence↗
PubMed1986

Meiotic disjunction of circular minichromosomes in yeast does not require DNA homology.

Circular plasmids containing an autonomously replicating sequence (ARS) and a centromeric DNA sequence (CEN) segregate as independent linkage groups during meiosis in Saccharomyces cerevisiae. If two genetically marked plasmids are present in the same diploid cell, their segregation during meiosis may be determined relative to each other. It has been observed that for centromere plasmids containing some DNA sequences in common, these plasmids tend to segregate away from each other at the first meiotic division [Clarke, L. & Carbon, J. (1980) Nature (London) 287, 504-509; Clarke, L., Fitzgerald-Hayes, M., Buhler, J.-M. & Carbon, J. (1981) Stadler Genet. Symp. 13, 9-23]. Here we show that nonhomologous plasmids, having no detectable DNA sequence cross-hybridization, also tend to disjoin from each other at the first meiotic division. Therefore, this nonrandom segregation to opposite poles can occur by mechanisms that do not involve DNA sequence homology. This process may be an active nonhomologous pairing system or it may reflect unknown physical restraints on the meiotic segregation of the two plasmids. In either case, this process cannot be used as a possible assay for homologous meiotic pairing.

Centromere↗
PubMed1986

Structure and sequence of the centromeric DNA of chromosome 4 in Saccharomyces cerevisiae.

The CEN4 sequences from chromosome 4 that impart mitotic stability to autonomously replicating (ARS) plasmids in yeast cells have been localized to a 1,755-base-pair (bp) fragment. This fragment could be cut in half to give two adjacent, nonoverlapping fragments, that each contained some mitotic stabilization sequences. One of the half-fragments worked as efficiently as the larger fragment from which it was derived, while the other half provided a much poorer degree of mitotic stabilization. Sequencing of 2,095 bp of DNA including this region revealed the presence of a centromere consensus sequence, elements I, II, and III (M. Fitzgerald-Hayes, L. Clarke, and J. Carbon, Cell 29:235-244, 1982), in the half-fragment providing high levels of mitotic stability. The poorly stabilizing half-fragment did not contain any obvious sequence homologies to other centromere sequences. Deletion analysis of the 1,755-bp fragment indicated that removal of the 14-bp element I plus 16 of the 82 bp of element II impaired mitotic stability. Removal of elements I and II eliminated the mitotic stability provided by the consensus sequence.

Amino Acid Sequence↗
PubMed1985

Mitotic stability of yeast chromosomes: a colony color assay that measures nondisjunction and chromosome loss.

A colony color assay that measures chromosome stability is described and is used to study several parameters affecting the mitotic maintenance of yeast chromosomes, including ARS function, CEN function, and chromosome size. A cloned ochre-suppressing form of a tRNA gene, SUP11, serves as a marker on natural and in vitro-constructed chromosomes. In diploid strains homozygous for an ochre mutation in ade2, cells carrying no copies of the SUP11 gene are red, those carrying one copy are pink, and those carrying two or more copies are white. Thus, the degree of red sectoring in colonies reflects the frequency of mitotic chromosome loss. The assay also distinguishes between chromosome loss (1:0 segregation) and nondisjunction (2:0 segregation). The most dramatic effect on improving mitotic stability is caused by increasing chromosome size. Circular chromosomes increase in stability through a size range up to approximately 100 kb, but do not continue to be stabilized above this value. However, linear chromosomes continue to increase in mitotic stability throughout the size range tested (up to 137 kb). It is possible that the mitotic stability of linear chromosomes is proportional to chromosome length, up to a plateau value that has not yet been reached in our synthetic constructions.

Chromosomes↗
PubMed1985

Stimulation of ovine placental lactogen secretion by arachidonic acid.

To determine whether arachidonic acid stimulates the secretion of ovine placental lactogen (oPL), arachidonic acid was infused as an intravenous bolus into pregnant ewes and fetuses. Plasma oPL concentrations were determined in mothers and fetuses before and for 5 h after infusion. The administration of 12.5 mg arachidonic acid (0.15-0.2 mg/kg, n = 11 experiments) to the pregnant ewes caused an increase in maternal plasma oPL concentrations of 73.9 +/- 15.6% (S.E.M.) and 60.8 +/- 18.1% above the pretreatment concentrations at 4 and 5 h respectively (P less than 0.01 in each instance). The infusion of 25 mg arachidonic acid (n = 8) caused increases of 96.0 +/- 19.1% and 100.3 +/- 26.4% (P less than 0.005), and the stimulation was not inhibited by the cyclo-oxygenase inhibitors indomethacin and ibuprofen. In contrast to arachidonic acid, vehicle alone or palmitic acid had no effects on plasma oPL concentrations. Despite the increase in maternal plasma oPL concentrations, plasma oPL concentrations in the fetus remained unchanged after the maternal infusions. The infusion of arachidonic acid (0.5-1.5 mg/kg) directly into six fetuses had no effects on either fetal or maternal oPL concentrations. These studies indicate that arachidonic acid stimulates maternal plasma oPL concentrations but has no effect on fetal oPL concentrations and the stimulation of oPL secretion is not due to the conversion of arachidonic acid to prostaglandins or other cyclo-oxygenase products.

Animals↗
PubMed1984

Deletion of plasmid sequences during Saccharomyces cerevisiae transformation.

Saccharomyces cerevisiae was transformed with DNA by the lithium acetate method. Mutation of nonselected markers on the transforming vector was observed at a frequency several orders of magnitude higher than spontaneous mutation frequencies. These mutations were shown to be deletions. Linearization of the vector before transformation stimulated deletion formation.

Base Sequence↗
PubMed1983

Instability of dicentric plasmids in yeast.

Dicentric plasmids containing either two copies of centromere 4 or one copy of centromere 4 and one copy of centromere 3 in the yeast plasmid vector YRp17 were constructed in vitro and introduced into yeast cells by DNA transformation. The resulting colonies were heterogeneous for a mixed population of rearranged plasmids. The rearrangements always involved deletion of one or both centromere sequences originally present on the plasmid. Heterogeneity was due to the continued production of deleted plasmids from a pool of unrearranged dicentric plasmids maintained within some of the yeast cells in the colony. The RAD52 gene product is known to be required for the repair of DNA double-strand breaks in yeast. Transformation of rad52 mutant yeast cells with dicentric plasmids gave rearranged plasmids similar to those observed with RAD+ yeast cells, but the transformation frequency was only 5-10% compared to transformation with monocentric plasmids. Also, the ratio of unrearranged dicentric plasmid to deleted plasmids was greatly reduced in the rad52-transformed cells. These observations are consistent with a model in which centromeric DNA sequences can interact independently with the yeast cell spindle apparatus. Occasional movement of centromeres to opposite poles may result in mechanical breakage of plasmid sequences. Plasmids deleted for one or both centromere sequences can be obtained from these broken molecules and are resistant to further rearrangement.

Centromere↗
PubMed1982

Reversion of a promoter deletion in yeast.

Promoter function in yeast has been examined by obtaining revertants of a his3 promoter deletion in vivo. Events which provide a new promoter for the his3 gene include insertion of the transposable element Ty1, rearrangements of the plasmid vector, and chromosomal mutations. A role for dicentric chromosomes as a source of the plasmid rearrangements is discussed.

Base Sequence↗
PubMed1982

[Post-operative respiratory function after subcutaneous and epidural morphine analgesia (author's transl)].

In 20 elderly patients who underwent cholecystectomy post-operative analgesia was obtained with morphine given either subcutaneously (n = 10) or epidurally (n = 10). Both groups were comparable as to age and pre-operative respiratory function values. On the first post-operative day, vital capacity, forced expiratory volume in one second and and paO2 were significantly higher in the epidural morphine group (respectively 70 +/- 6 p. cent and 68 +/- 6 p. cent of pre-operative values, and 74 +/- 3 mmHg) (mean +/- s.e.m.) than in the subcutaneous morphine group, where the corresponding figures were 52 +/- 4 p. cent, 48 +/- 5 p. cent and 63 +/- 2 mmHg respectively. PaCO2 was unchanged in both groups. These data indicate that epidural morphine analgesia to some extent reduces the post-operative respiratory dysfunction observed after abdominal surgery.

Aged↗
PubMed1977

Colostomy.

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Aftercare↗