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T Conway

Publications and source records attributed to T Conway.

At least 91 records · Page 5Linked to original sources
PubMed1988

Breast cancer family history as a risk factor for early onset breast cancer.

Since full breast cancer screening is not generally recommended for young women, it is important to identify individuals who are at higher risk for early onset breast cancer. We investigated the relationship between age of onset of breast cancer in 328 probands (consecutively ascertained patients from our oncology clinic) and breast cancer incidence and age of onset in their female relatives. We found that a family history of early onset breast cancer was associated with higher risk of early onset breast cancer. A family history of early onset breast cancer occurred more frequently among young (less than 40) breast cancer probands than among older (greater than or equal to 40) breast cancer probands (p less than 0.001; OR = 23). This relationship was particularly evident when the analysis was restricted to the hereditary breast cancer probands (p less than 0.001; OR = 44). We also observed a positive family history of breast cancer (any age) more frequently in young breast cancer probands than in older breast cancer probands (p less than 0.001; OR = 2.8). These observations have important pragmatic implications for surveillance. We recommend intense surveillance for breast cancer, initiated earlier, for women with close relatives diagnosed with early onset breast cancer.

Adult↗
PubMed1988

Age-of-onset heterogeneity in hereditary breast cancer: minimal clues for diagnosis.

Knowledge of the family history of cancer may significantly influence diagnosis and surgical management. Hereditary breast cancer (HBC) is common and accounts for approximately 9% of the total breast cancer burden. The pattern of HBC's natural history, including age of onset, increased incidence of bilaterality, integral tumor combinations in certain kindreds, and vertical transmission consonant with an autosomal dominantly inherited factor, when observed in context with the family history, enables pattern recognition so that the diagnosis might be facilitated. We describe seven families from our Hereditary Cancer Consultation Center (HCCC) and the Creighton Oncology Clinic which are noteworthy for extraordinarily early age of onset. This appears to be an additional example of heterogeneity in HBC and may represent the first account of this remarkable subset. The manner in which age of onset can be incorporated with other aspects of natural history for expediting diagnosis is discussed.

Age Factors↗
PubMed1988

Breast cancer diagnosis in a putative obligate gene carrier. A family study.

Hereditary breast cancer is common and accounts for about 8% of all breast cancer. It has a distinctive natural history characterized by early age of onset, excess bilaterality, and vertical transmission consonant with an autosomal dominant inheritance pattern. We describe an informative kindred wherein this knowledge was effectively applied, with resultant high yield: early breast cancer diagnosis in a mother who was a putative obligate gene carrier, and a contralateral breast cancer diagnosis in her daughter. A more intensive stance on breast cancer diagnosis must be employed in members of hereditary breast cancer kindreds who are judged to be at inordinately increased risk. Breast cancer control through application of genetic knowledge is readily achievable in the clinical practice setting.

Adult↗
PubMed1988

Expression of Different Levels of Ethanologenic Enzymes from Zymomonas mobilis in Recombinant Strains of Escherichia coli.

The expression of Zymomonas mobilis genes encoding pyruvate decarboxylase and alcohol dehydrogenase II in Escherichia coli converted this organism from the production of organic acids to the production of ethanol. Ethanol was produced during both anaerobic and aerobic growth. The extent to which these ethanologenic enzymes were expressed correlated with the extent of ethanol production. The replacement of organic acids with ethanol as a metabolic product during aerobic and anaerobic growth resulted in dramatic increases in final cell density, indicating that these acids (and the associated decline in pH) are more damaging than the production of ethanol. Of the plasmids examined, the best plasmid for growth and ethanol production expressed pyruvate decarboxylase and alcohol dehydrogenase II at levels of 6.5 and 2.5 IU/mg of total cell protein, respectively.

Journal Article↗
PubMed1988

Phosphoglycerate kinase gene from Zymomonas mobilis: cloning, sequencing, and localization within the gap operon.

The Zymomonas mobilis gene encoding phosphoglycerate kinase (EC 2.7.3.2), pgk, has been cloned into Escherichia coli and sequenced. It consists of 336 amino acids, including the N-terminal methionine, with a molecular weight of 41,384. This promoterless gene is located 225 base pairs downstream from the gap gene and is part of the gap operon. Previous studies have shown that the specific activities of glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate kinase do not change coordinately in Z. mobilis, although the two enzymes appear to be under the control of a common promoter. The translated amino acid sequence for the Z. mobilis phosphoglycerate kinase is less conserved than those of eucaryotic genes. A comparison of known sequences for phosphoglycerate kinase revealed a high degree of conservation of structure with 102 amino acid positions being retained by all. In general, the amino acid positions at the boundaries of beta-sheet and alpha-helical regions and those connecting these regions were more highly conserved than the amino acid positions within regions of secondary structure.

Amino Acid Sequence↗
PubMed1988

Synthesis of "no-carrier-added" carbon-11 SarCNU: the sarcosinamide analog of the chemotherapeutic agent BCNU.

Carbon-11-labeled SarCNU [N-(2-chloroethyl)-N-nitroso-N'-(carboxamidomethylene)-N'-(methyl) - [11C]-urea], a potential chemotherapeutic agent, has been prepared by the nitrosation of the corresponding urea, N-(2-chloroethyl)-N'-(carboxamidomethylene)-N'-(methyl) [11C]urea (SarCU). SarCU was prepared by reacting sarcosinamide with [11C]-2-chloroethylisocyanate, which was itself prepared by reacting [11C]-phosgene with 2-chloroethylamine hydrochloride suspended in dioxane. The synthesis yielded [11C]SarCNU with an average radiochemical purity of 95% in an average overall radiochemical yield of 18% relative to the activity measured at the end of [11C]phosgene introduction.

Antineoplastic Agents↗
PubMed1987

Genetic engineering of ethanol production in Escherichia coli.

The genes encoding essential enzymes of the fermentative pathway for ethanol production in Zymomonas mobilis, an obligately ethanologenic bacterium, were inserted into Escherichia coli under the control of a common promoter. Alcohol dehydrogenase II and pyruvate decarboxylase from Z. mobilis were expressed at high levels in E. coli, resulting in increased cell growth and the production of ethanol as the principal fermentation product from glucose. These results demonstrate that it is possible to change the fermentation products of an organism, such as E. coli, by the addition of genes encoding appropriate enzymes which form an alternative system for the regeneration of NAD+.

Alcohol Dehydrogenase↗
PubMed1987

Expression Vector for Zymomonas mobilis.

This study describes the construction of several useful cloning vectors which can be conjugated from Escherichia coli into Zymomonas mobilis at high frequency, approaching 10 per donor or recipient. These vectors contain a broad-host-range replicon and mob site from RSF1010, a chloramphenicol acyltransferase gene under the control of an enteric consensus promoter, and a second mob site (originally derived from RP4). The addition of this second mob site appears to be responsible for a 2-order-of-magnitude increase in the efficiency of transfer into Z. mobilis. Such vectors may be useful for other gram-negative bacteria in which conjugation efficiencies are low. These vectors are stably maintained in Z. mobilis with no detectable loss of plasmid after 50 generations in the absence of selective pressure. One of these, pLOI193, contains the tetracycline gene from pBR322 and associated cloning sites for insertional inactivation. Another, pLOI204, contains a Z. mobilis promoter immediately upstream from a BamHI site which can be used for cloning. This promoter has been shown to efficiently drive the expression of beta-galactosidase in both Z. mobilis and E. coli. This promoter fragment from Z. mobilis has been sequenced, and the site for transcriptional initiation in E. coli and Z. mobilis has been identified.

Journal Article↗
PubMed1987

Glyceraldehyde-3-phosphate dehydrogenase gene from Zymomonas mobilis: cloning, sequencing, and identification of promoter region.

The gene encoding glyceraldehyde-3-phosphate dehydrogenase was isolated from a library of Zymomonas mobilis DNA fragments by complementing a deficient strain of Escherichia coli. It contained tandem promoters which were recognized by E. coli but appeared to function less efficiently than the enteric lac promoter in E. coli. The open reading frame for this gene encoded 337 amino acids with an aggregate molecular weight of 36,099 (including the N-terminal methionine). The primary amino acid sequence for this gene had considerable functional homology and amino acid identity with other eucaryotic and bacterial genes. Based on this comparison, the gap gene from Z. mobilis appeared to be most closely related to that of the thermophilic bacteria and to the chloroplast isozymes. Comparison of this gene with other glycolytic enzymes from Z. mobilis revealed a conserved pattern of codon bias and several common features of gene structure. A tentative transcriptional consensus sequence is proposed for Z. mobilis based on comparison of the five known promoters for three glycolytic enzymes.

Amino Acid Sequence↗
PubMed1987

Promoter and nucleotide sequences of the Zymomonas mobilis pyruvate decarboxylase.

DNA sequence analysis showed that pyruvate decarboxylase (one of the most abundant proteins in Zymomonas mobilis) contains 559 amino acids. The promoter for the gene encoding pyruvate decarboxylase was not recognized by Escherichia coli, although the cloned gene was expressed at relatively high levels under the control of alternative promoters. The promoter region did not contain sequences which could be identified as being homologous to the generalized promoter structure for E. coli. Hydropathy plots for the amino acid sequence indicated that pyruvate decarboxylase contains a large number of hydrophobic domains which may contribute to the thermal stability of this enzyme.

Amino Acid Sequence↗
PubMed1987

Gene expression in Zymomonas mobilis: promoter structure and identification of membrane anchor sequences forming functional lacZ' fusion proteins.

We have described a procedure for the isolation of lacZ' fusion genes which contain anchor sequences conferring membrane association. This method was used to isolate fragments of DNA from Zymomonas mobilis which contain promoter activity and amino-terminal sequences. The sequences and transcriptional initiation sites of three of these were compared. Both Escherichia coli and Z. mobilis recognized similar regions of DNA for transcriptional initiation. Five to eight consecutive hydrophobic amino acids in the amino terminus served to anchor these hybrid proteins to the membrane in both E. coli and Z. mobilis. General features observed in the Z. mobilis fragments included partial sequence homology with the -35 region sequence of E. coli, repetitive and palindromic A + T-rich regions preceding and adjoining the -10 region, a sequence resembling the consensus sequence of E. coli in the -10 region, and a potential ribosomal-binding site (AGGA) 8 to 12 bases upstream from an in-frame start codon. The level of expression of fusion proteins was generally higher in E. coli than in Z. mobilis. This higher level of expression in E. coli may result from multiple sites of transcriptional initiation and higher plasmid copy number.

Bacterial Proteins↗
PubMed1987

Cloning and sequencing of the alcohol dehydrogenase II gene from Zymomonas mobilis.

The gene which encodes alcohol dehydrogenase II (adhB) from Zymomonas mobilis was cloned in Escherichia coli as a 1.4-kilobase DNA fragment by using a novel indicator plate which directly detects the expression of this activity by recombinant colonies. The DNA sequence for this clone contained an open reading frame encoding a polypeptide of 383 amino acids, with a molecular weight of 40,141. Although this protein exhibited very little homology with other known alcohol dehydrogenases, the predicted amino acid composition was in excellent agreement with that reported for the purified alcohol dehydrogenase II protein from Z. mobilis. In Z. mobilis, the adhB gene was transcribed from tandem promoters which were separated by 100 base pairs and ended with a transcriptional terminator (13-base-pair palindrome). In Escherichia coli, only one of the Z. mobilis promoters was used, despite apparent similarity to the enteric consensus promoter. The adhB gene was transcribed at low levels in E. coli from the P2 promoter of Z. mobilis but was expressed well in E. coli under control of the lac promoter (approximately 0.25% of the total cell protein).

Alcohol Dehydrogenase↗
PubMed1987

Glycolytic flux in Zymomonas mobilis: enzyme and metabolite levels during batch fermentation.

The rate at which Z. mobilis (Entner-Doudoroff pathway) converts high concentrations of glucose (20%) into ethanol plus CO2 changes as ethanol accumulates in the surrounding broth. This decline in glycolytic activity (per milligram of cell protein) does not result from inhibitory effects of ethanol, which can be reversed immediately by ethanol removal. The peak of fermentative activity (58 mumol of CO2 evolved per mg of cell protein per h) occurred after the accumulation of 1.1% ethanol (18 h) and declined to one-half this rate after 30 h (6.2% accumulated ethanol), although the cell number continued to increase. These times corresponded to the end of exponential growth and to the onset of the stationary phase (on the basis of measurement of cell protein), respectively. An examination of many of the requirements for fermentation (nucleotides, magnesium, enzyme levels, intracellular pH, delta pH) revealed three possible reasons for this early decline in activity: decreased abundance of nucleotides, a decrease in internal pH from 6.3 to 5.3, and a decrease in the specific activities of two glycolytic enzymes (pyruvate kinase and glyceraldehyde-3-phosphate dehydrogenase). 31P nuclear magnetic resonance spectra of perchlorate extracts from cells fermenting in broth revealed very low levels of glycolytic intermediates (Entner-Doudoroff pathway) in cells examined at the peak of fermentative activity (18-h cells) in comparison with cells examined at a later stage (30-h cells), consistent with limitation of the fermentation rate by glycolytic enzymes near the end of the pathway. It is likely that cell death (loss of colony-forming ability) and the collapse of delta pH also contribute to the further decline in fermentative activity after 30 h.

Adenosine Diphosphate↗
PubMed1986

Intestinal calcium transport in the spontaneously hypertensive rat: response to calcium depletion.

We previously found intestinal Ca2+ transport to be lower in the spontaneously hypertensive (SH) as compared with the Wistar-Kyoto control (WKY) rat. These animals were fed a relatively high (1%) Ca2+ diet, and the concentration of 1 alpha,25-dihydroxycholecalciferol [1 alpha,25(OH)2D3] in serum was the same in both groups. In the present experiment we tested the possibility that the lower Ca2+ transport in the SH rat was the result of unresponsiveness to 1 alpha,25(OH)2D3. We fed diets high and low in Ca2+ and measured serum 1 alpha,25(OH)2D3 and Ca2+ transport. Serum 1 alpha,25(OH)2D3 increased in response to Ca2+ depletion at both 5 and 12 wk in both the WKY and SH rat. With high-Ca2+ diet, Ca2+ transport was lower in SH than in WKY when studied 1) in vitro in duodenum at 5 wk of age, and 2) in vivo in proximal and distal small intestine at 12 wk of age. Ca2+ transport increased in SH in response to Ca2+ depletion, but not in WKY, except in distal small intestine in vivo at 12 wk. In summary, although Ca2+ transport is lower in the SH as compared with the WKY rat when vitamin D activity is basal through feeding a high-Ca2+ diet, Ca2+ transport increases in the SH rat in response to the increase in 1 alpha,25(OH)2D3 produced by feeding a low-Ca2+ diet. We conclude that 1) the vitamin D-regulated component of mediated Ca2+ transport is intact in the SH rat and is unrelated to hypertension, and 2) mediated Ca2+ transport under basal conditions, i.e., nonvitamin D-regulated, differs in the SH and WKY rats and may be related to hypertension.

Animals↗