Biomedical subjects

L R Guo

Publications and source records attributed to L R Guo.

6 recordsLinked to original sources

PubMed2001

Incidental malignancy in internal thoracic artery lymph nodes.

The incidental finding of malignant internal thoracic lymph nodes while mobilizing the internal thoracic artery (ITA) for coronary bypass grafting has not to our knowledge been previously reported. The cases of 3 male patients who underwent surgery between January 1990 and January 1993 and in whom malignant lymph nodes were found in the ITA pedicle are reviewed. One individual was found to have metastatic carcinoma of the breast, whereas the other 2 were discovered to have previously undiagnosed lymphomas. After undergoing further relevant investigation and treatment, all 3 patients remain free of recurrent disease 6.8 to 9.8 years after their original cardiac surgery. Primary or metastatic malignancy may be encountered in the course of ITA mobilization for grafting. Abnormally enlarged internal thoracic lymph nodes should be sent for pathologic examination.

Aged↗

PubMed2001

Effect of distal graft anastomosis site on retrograde perfusion and flow patterns of native coronary vasculature.

BACKGROUND: To select the site of a target vessel for distal anastomosis surgeons use different approaches. Some try to place the graft as close to the stenosis as possible, whereas others routinely anastomose the graft onto the distal portion. In this latter case the proximal portion and its tributaries are perfused from the graft in a retrograde rather than an antegrade fashion. The aim of this study was to investigate the effect of local hemodynamics associated with the different location of distal anastomoses on flow patterns in the proximal native artery and its branches. METHODS: Computational fluid dynamic and in vitro model studies were carried out in a control model composed of a straight tube (host) with a 45E side branch and models in which the proximal end of the host had various degrees of stenosis; a 45E end-to-side "graft" anastomosis was introduced either proximal (upstream) or distal (downstream) to the branch. RESULTS: Placing the graft proximal to the branch largely preserved the flow patterns that were seen in the control model. Placing the graft distal to the branch, however, introduced an extensive region of relatively stagnant flow in the native vessel near the branch. Such regions are known to promote thrombus formation that could ultimately lead to occlusion of the retrograde portion of the host vessel. CONCLUSIONS: This study suggests that, although often less convenient surgically, long-term outcome of coronary artery bypass grafting may be improved by placing grafts in the most proximal portion of the native vessel, as close to the occlusion or stenosis as possible for better preservation of a proximal artery and its branches.

Blood Flow Velocity↗

PubMed1996

Single and double infections with Wolbachia in the parasitic wasp Nasonia vitripennis: effects on compatibility.

Wolbachia are cytoplasmically inherited bacteria responsible for reproductive incompatibility in a wide range of insects. There has been little exploration, however, of within species Wolbachia polymorphisms and their effects on compatibility. Here we show that some strains of the parasitic wasp Nasonia vitripennis are infected with two distinct bacterial strains (A and B) whereas others are singly infected (A or B). Double and single infections are confirmed by both PCR amplification and Southern analysis of genomic DNA. Furthermore, it is shown that prolonged larval diapause (the overwintering stage of the wasp) of a double-infected strain can lead to stochastic loss of one or both bacterial strains. After diapause of a double-infected line, sublines were produced with AB, A only, B only or no Wolbachia. A and B sublines are bidirectionally incompatible, whereas males from AB lines are unidirectionally incompatible with females of A and B sublines. Results therefore show rapid development of bidirectional incompatibility within a species due to segregation of associated symbiotic bacteria.

Animals↗

PubMed1995

Evolution and phylogeny of Wolbachia: reproductive parasites of arthropods.

Wolbachia are cytoplasmically inherited bacteria found in reproductive tissues of many arthropod species. These bacteria are associated with reproductive alterations in their hosts, including parthenogenesis, reproductive incompatibility and feminization. A fine-scale phylogenetic analysis was done using DNA sequences from ftsZ, a rapidly evolving bacterial cell-cycle gene. ftsZ sequences were determined for 38 different Wolbachia strains from 31 different species of insects and one isopod. The following results were found: (i) there are two major division of Wolbachia (A and B) which diverged 58-67 millions years before present based upon synonymous substitution rates; (ii) a general concordance is found between the ftsZ and 16S rDNA phylogenies, indicating that these represent bacterial strain (rather than simply gene) phylogenies; however, a possible example of recombination between A and B division bacteria may have occurred in the feminizing Wolbachia present in an isopod; (iii) extensive horizontal transmission of Wolbachia has occurred between insect taxa, including different insect orders; one strain in particular (designated Adm) shows extensive recent horizontal transmission; (iv) there is an association between the Wolbachia found in a parasitic wasp (Nasonia) and its fly host (Protocalliphora), suggesting exchange of bacteria between these species; (v) parthenogenesis induction has evolved several times among the Wolbachia; and (vi) some insects harbour infections with more than one Wolbachia strain, even within individual insects.

Animals↗

PubMed1994

Cardiac storage with UW solution and glucose.

Previous investigations from our institution using an isolated human cardiomyocyte model concluded that glucose supplementation of University of Wisconsin solution (UWS) was beneficial with respect to adenine nucleotide and protein recovery. We wished to confirm these results using an isolated heart model. Rodent hearts were frozen in liquid nitrogen (control) or flushed and stored in UWS for 8 hours at 0 degrees C or UWS supplemented with 10, 20, or 30 mmol/L glucose. Experimental hearts were assessed at end-storage or after 45 minutes of reperfusion on a Langendorff apparatus. Adenine nucleotides were assessed by high performance liquid chromatography. In parallel experiments, ventricular function was assessed before and after storage in Langendorff-perfused hearts instrumented with a left ventricular balloon. Glucose supplementation was associated with greater poststorage (20 and 30 mmol/L glucose) and postreperfusion (10, 20, and 30 mmol/L glucose) adenosine triphosphate levels than unmodified UWS. Developed pressure (expressed as a percentage of control values) was increased with 10 mmol/L glucose (75.2% +/- 7.9%, mean +/- standard deviation) compared with unmodified UWS (64.6% +/- 6.6%; p < 0.05). Coronary flow was greater with 10 (72.6% +/- 10.7%) or 20 mmol/L (71.2% +/- 12.5%) versus 0 mmol/L glucose (58.6% +/- 12.1%, p < 0.05). The data support previous in vitro findings and suggest that the addition of 10 mmol/L glucose to UWS is associated with enhanced recovery after prolonged hypothermic storage.

Adenine Nucleotides↗

PubMed1990

[G-banding and high resolution chromosome study of a human lung adenocarcinoma cell line LGC-7910].

G-banding and high resolution chromosome banding techniques were used in studying a human lung adenocarcinoma cell line LGC-7910. One hundred cells were counted at Passage 150. Ten, twelve and ten cells were analyzed at Passages 150, 173 and 183, respectively. The model number of chromosome in this cell line was 67-69. A number of marker chromosomes related to complex chromosomal rearrangement was observed. The analysis of chromosomes at the different passages showed a stability during subculture of the cell line. It was found that the cell line had partial deletion of the short arm on chromosome 7 (with breakpoint at 7p15.3-p13), rearrangement of the arm on chromosome 1 (with breakpoint at 1p13.1) and increase in chromosome 7 number. The results suggested that such chromosome alteration be related to the expression of activated oncogenes during carcinogenesis.

Adenocarcinoma↗