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Biomedical subjects

P Cao

Publications and source records attributed to P Cao.

At least 19 recordsLinked to original sources
PubMed2006

A modified method of activity-based costing for objectively reducing cost drivers in hospitals.

OBJECTIVES: Activity-based costing (ABC) is widely used to precisely allocate indirect costs to medical services. In the ABC method, the indirect cost is divided among the medical services in proportion to the volume of "cost drivers", for example, labor hours and the number of hours of surgery. However, the workload of data collection of cost drivers can be time-consuming and a considerable burden if there are many cost drivers. The authors aim to develop a method for objectively reducing the cost drivers used in the ABC method. METHODS: In the ABC method, the cost driver is assigned for each activity. We assume that these activities and cost drivers are the best combination. Our method, that is cost driver reduction (CDR), can objectively select surrogates of the cost drivers for each activity in ABC from candidate cost drivers. Concretely, the total indirect cost of an activity is temporarily allocated to the medical services using each candidate of cost drivers. The difference between the costs calculated by each candidate and the proper cost driver used in ABC is calculated to evaluate the similarity by the evaluation function. RESULTS: We estimated the cost of laboratory tests using our method and revealed that the number of cost drivers could be reduced from seven in the ABC to four. Similarly, the results of cost estimation obtained by our method were as accurate as those calculated using the ABC. CONCLUSIONS: Our method provides two advantages compared to the ABC method: 1) it provides results that are as accurate as those of the ABC method, and 2) it is simpler to perform complicated estimation of hospital costs.

Accounting↗
PubMed2005

Conversion to open repair after endografting for abdominal aortic aneurysm: causes, incidence and results.

OBJECTIVE: To evaluate frequency, causes and results of conversion to Open repair (OR) after endovascular repair (EVAR) in a single centre during an 8-year period. DESIGN: Six hundred and forty-nine consecutive patients undergoing EVAR were followed up prospectively for endograft-related complications. OUTCOMES: Early conversion was any OR during or within 30 days from the primary EVAR. Late conversion was any OR with removal of the endograft after 30 days since a completed EVAR procedure. RESULTS: Median patient follow-up was 38 months (1-93 months). Conversion to OR was performed in 38 patients; nine early and 29 late. Most (7/9) early conversions were due to extensive vessel calcification. Peri-operative mortality was 22% (2/9). Late conversions occurred at a median of 33 months after primary EVAR: 29 were elective and 4 urgent. During the same interval, 79 secondary endovascular interventions were performed, 7 of which failed. The risk of conversion to OR was 9% at 6 years. At multivariate logistic regression analysis, no single factor (short, large or angulated neck, suprarenal fixation, large pre-operative diameter, iliac aneurysms, ASA score risk) was associated with the risk of late failure requiring conversion to OR. CONCLUSION: The risk of death after early conversion should be recognized, to avoid forcing morphological indications for primary EVAR. Occurrence of late conversion after EVAR is not negligible, affecting almost 1 out of 10 patients after 6 years. In the presence of an expanding aneurysm after EVAR, especially after a failed secondary endovascular correction, an aggressive attitude in fit patients allows outcomes at similar to those of primary OR.

Aged↗
PubMed2005

Comparison of surveillance vs Aortic Endografting for Small Aneurysm Repair (CAESAR) trial: study design and progress.

OBJECTIVE: The CAESAR Trial aims to assess the outcome of endovascular repair (EVAR) vs surveillance of small abdominal aortic aneurysms (AAA) with maximum diameter of 4.1-5.4 cm on computerised tomography (CT) scan. DESIGN: Patients between 50 and 80 years of age, with small AAA, anatomically suitable for EVAR, are randomly allocated to early EVAR or surveillance. The primary outcome measure is survival. Secondary endpoints include: aneurysm-related deaths (defined as any death caused directly or indirectly by rupture or endovascular/open aneurysm repair), AAA rupture, peri-operative or late complications, conversion to open repair, complications associated with delayed treatment including loss of treatment options, AAA growth rates and quality of life. Target recruitment is 740 patients to show that early EVAR is associated with a 15% survival benefit at 54 months. PROGRESS: Randomization started in September 2004. By the end of April 2005, 86 patients had been enrolled by 10 active European centres. Completion of recruitment is expected for September 2006 and publication of the results in mid 2007.

Aged↗
PubMed2003

Does gender influence outcome of AAA endoluminal repair?

BACKGROUND: It has been suggested that female patients have a less favourable outcome of endoluminal repair of abdominal aortic aneurysms. Yet, data on stratified per gender are lacking. METHODS: We reviewed our prospective database of 402 endografts over a 4-year period and the peri- and postoperative course in the 25 (6%) female patients was compared with the 377 (94%) male patients. Median follow-up was 24 months (range 1-56 months). Logistic regression analysis was performed to test the effect of five confounding variables (gender, age, ASA grade IV, EUROSTAR class D or E, AAA diameter) on failure of AAA exclusion. RESULTS: There were no perioperative deaths in the female group and 5 (1.3%) in the male group (p = 0.8). Major perioperative morbidity occurred in 17% versus 6% (OR 3.7; 95% CI 1.2-10.6; p = 0.026). There were 1 (4%) and 5 (1%) conversions to open repair in the female and male groups, respectively (p = 0.3). Late failure of AAA exclusion occurred in 5 (21%) and 26 (7%) patients, respectively (p = 0.03). Of the five variables examined for their influence on failure of AAA exclusion, female gender (hazard ratio 4.42; 95% CI 1.4-13.4; p = 0.009) and AAA diameter (hazard ratio 1.05; 95% CI 1.009-1.09; p = 0.017), were positive independent predictors of late failure of AAA exclusion on multivariate analysis. CONCLUSION: Endoluminal AAA repair in female patients appear associated with a less favorable outcome when compared to their male counterparts. These data may be taken into consideration when endoluminal AAA repair is suggested to a female patient.

Aged↗
PubMed2002

Eversion vs conventional carotid endarterectomy: a systematic review.

OBJECTIVE: to determine whether eversion carotid endarterectomy (CEA) was safe and more effective than conventional CEA. METHODS: controlled trials comparing eversion vs conventional technique for CEA were identified from the Cochrane Stroke Review Group database plus additional hand searching. Researchers were contacted to identify additional published and unpublished studies. Randomised and pseudorandomised trials comparing eversion to conventional techniques in patients undergoing CEA were examined. Outcomes included stroke and death, carotid restenosis/occlusion, and local complications. RESULTS: five trials were included comprising 2465 patients and 2590 arteries. There were no significant differences in the rate of perioperative stroke or death (1.7% vs 2.6%, odds ratio [OR] 0.44, 95% confidence interval [CI] 0.10-1.82) and stroke during follow-up (1.4% vs 1.7%; OR: 0.84; 95% CI: 0.43-1.64) between eversion and conventional CEA techniques. Eversion CEA was associated with a significantly lower rate of restenosis >50% during follow-up (2.5% vs 5.2%, OR: 0.48, 95% CI: 0.32-0.72). There were no statistically significant differences in local complications between the eversion and conventional group. When eversion procedures were compared with patch procedures only, non-significant differences were found in primary outcomes. CONCLUSIONS: eversion CEA may be associated with low risk of arterial occlusion and restenosis. However, numbers are too small to definitively assess the benefits and disadvantages of eversion CEA. Reduced restenosis rates did not appear to be associated with clinical benefit in terms of reduced stroke risk, either perioperatively or later. Until further evidence is available, the choice of the CEA technique should be based on the experience and familiarity of the individual surgeon.

Adult↗
PubMed2002

Does the presence of an iliac aneurysm affect outcome of endoluminal AAA repair? An analysis of 336 cases.

OBJECTIVE: To determine whether the presence of an iliac aneurysm compromises outcome of endovascular exclusion of AAA and to ascertain the fate of the iliac aneurysmal sac. PATIENTS AND METHODS: Between April 1997 and March 2001, data on 336 consecutive patients undergoing endovascular repair for AAA were entered in a prospective database. Suitability for endovascular repair was assessed by preoperative contrast-enhanced computed tomography. A maximum common iliac artery (CIA) diameter > or = 20 mm was defined as iliac aneurysm. Patients with and without iliac aneurysms were compared to early (immediate conversion or perioperative death) and late failure (increase in aneurysm diameter or persisting graft-related endoleak, or late AAA rupture or conversion). RESULTS: Fifty-nine patients (18%) had iliac aneurysms, 19 were bilateral, for a total of 78 aneurysmal iliac arteries (median diameter 23 mm; range 20-50 mm). A distal seal was achieved by landing in 33 external iliac arteries, in 20 ectatic CIAs, and in 25 normal CIAs. Operating time differed significantly between patients with and without CIA aneurysms (153 +/- 71 vs 123 +/- 55 min, p = 0.0001), whereas no statistically significant differences were found with respect to early and late failure (2% vs 3%, p = 0.5 and 14% vs 8%, p = 0.11, respectively). There were no cases of buttock or colon necrosis. At a median follow-up of 14 months (range 0-46; i.q.r. 7-27 months) common iliac diameter decreased > or = 2 mm in 49 cases, remained stable in 25, and increased > or = 2 mm in 3. CONCLUSION: The presence of iliac aneurysm rendered endoluminal AAA repair more complex but did not affect feasibility and long-term outcome of the procedure. In our experience internal iliac exclusion was never associated with significant morbidity. These data may be useful when considering endovascular repair in high-risk patients with challenging anatomy.

Aged↗
PubMed2001

Parameters influencing membrane CD14 expression and soluble CD14 levels in sepsis.

INTRODUCTION: Membrane (mCD14) and soluble (sCD14) CD14 are pattern recognition receptors for bacterial cell wall fragments. They play an important role in the generation of the innate immune response against bacterial pathogens. Differential expression of these receptors may be relevant for the clinical course of patients with sepsis. PATIENTS AND METHODS: 32 patients with an early onset of sepsis (duration of symptoms < 24h) were examined repeatedly by flow cytometry for expression of mCD14, and by ELISA for levels of sCD14, leukocyte elastase and C-reactive Protein (CRP). RESULTS: At study entry, mCD14 expression was reduced in all patients with sepsis, but returned to normal levels during the course of the disease in survivors only. mCD14 was found to be inversely correlated with severity of disease, leukocyte elastase, and C-reactive protein. Among patients with severe disease and Apache II scores >or= 20, sCD14 levels at study entry were significantly higher in those who survived by day 28, as compared to non-survivors (p = 0.02). CONCLUSION: The data presented are compatible with a recently published hypothesis derived from in vitro experiments suggesting that leukocyte elastase may be responsible for cleavage of mCD14 from the monocyte surface. The data also suggest that higher sCD14 levels may be beneficial in sepsis. Persistently reduced mCD14 expression seems to be a marker for severity of disease in patients with sepsis.

APACHE↗
PubMed2001

Endovascular abdominal aortic aneurysm repair in high-risk patients: a single centre experience.

OBJECTIVES: to evaluate the role of endovascular repair (ER) of abdominal aortic aneurysm (AAA) repair in American Society for Anaesthesiology [ASA] class IV patients. PATIENTS AND METHODS: between April 1997 and March 2000, 266 consecutive patients underwent ER for AAA. There were 26 patients (10%) with ASA grade IV. The remaining 240 patients, ASA grade between I and III (ASA<IV group), were compared with the ASA IV group. Mean follow-up was 11.6 months (range 1-32 months). Increase in AAA diameter after ER or persisting graft-related endoleak were defined as failure of AAA exclusion. Regression analysis was performed to test the effect of five confounding variables on failure of AAA exclusion and perioperative mortality. RESULTS: patients in the ASA IV group were significantly older than patients in ASA <IV group (mean age: 74 years vs 70 years p=0.005). AAA were larger (mean diameter: 56 mm vs 50 mm p =0.002) and more extensive (class E of EUROSTAR classification: 27% vs 5.8% p =0.002). There were two perioperative deaths in the ASA IV group and one in the ASA<IV group (8% vs 0.4%; RR 19; 95% CI 1.8-202 p=0.01). Major perioperative morbidity occurred in 8% of patients in the ASA IV group and in 3.3% in the ASA<IV group (n.s.). There were no conversions to open repair in the ASA IV group while six were performed in the ASA<IV group (n.s.). Length of hospitalisation was significantly longer for patients in the ASA IV group: 7.8 days vs 3.2 days (p =0.001). Operative times and blood loss were similar. Failure of AAA exclusion occurred in two patients (8%) in the ASA IV group and in four patients (1.6%) in the ASA<IV group (n.s.). On life table analysis, survival rates at 26 months were 76% in the ASA IV group and 89% in the ASA<IV group (p =0.004). Five variables were examined by regression analysis and no independent predictors of failure of AAA exclusion and operative mortality were found. CONCLUSIONS: ER in ASA IV patients is feasible and effective with acceptable actuarial survival rates. However, the endovascular procedure in these patients is associated with higher major systemic morbidity, mortality, and prolonged hospitalisation rates.

Aged↗
PubMed2001

Amino-terminal hydrophobic region of Helicobacter pylori vacuolating cytotoxin (VacA) mediates transmembrane protein dimerization.

Helicobacter pylori VacA is a secreted protein toxin that forms channels in lipid bilayers and induces multiple structural and functional alterations in eukaryotic cells. A unique hydrophobic segment at the amino terminus of VacA contains three tandem repeats of a GxxxG motif that is characteristic of transmembrane dimerization sequences. To examine functional properties of this region, we expressed and analyzed ToxR-VacA-maltose binding protein fusions using the TOXCAT system, which was recently developed by W. P. Russ and D. M. Engelman (Proc. Natl. Acad. Sci. USA 96:863-868, 1999) to study transmembrane helix-helix associations in a natural membrane environment. A wild-type VacA hydrophobic region mediated insertion of the fusion protein into the inner membrane of Escherichia coli and mediated protein dimerization. A fusion protein containing a mutant VacA hydrophobic region (in which glycine 14 of VacA was replaced by alanine) also inserted into the inner membrane but dimerized significantly less efficiently than the fusion protein containing the wild-type VacA sequence. Based on these results, we speculate that the wild-type VacA amino-terminal hydrophobic region contributes to oligomerization of the toxin within membranes of eukaryotic cells.

Amino Acid Sequence↗
PubMed2001

Antigenic diversity among Helicobacter pylori vacuolating toxins.

Helicobacter pylori vacuolating cytotoxin (VacA) is a secreted protein that induces vacuolation of epithelial cells. To study VacA structure and function, we immunized mice with purified type s1-m1 VacA from H. pylori strain 60190 and generated a panel of 10 immunoglobulin G1kappa anti-VacA monoclonal antibodies. All of the antibodies reacted with purified native VacA but not with denatured VacA, suggesting that these antibodies react with conformational epitopes. Seven of the antibodies reacted with both native and acid-treated VacA, which suggests that epitopes present on both oligomeric and monomeric forms of the toxin were recognized. Two monoclonal antibodies, both reactive with epitopes formed by amino acids in the carboxy-terminal portion of VacA (amino acids 685 to 821), neutralized the cytotoxic activity of type s1-m1 VacA when toxin and antibody were mixed prior to cell contact but failed to neutralize the cytotoxic activity of type s1-m2 VacA. Only 3 of the 10 antibodies consistently recognized type s1-m1 VacA toxins from multiple H. pylori strains, and none of the antibodies recognized type s2-m2 VacA toxins. These results indicate that there is considerable antigenic diversity among VacA toxins produced by different H. pylori strains.

Animals↗
PubMed2001

A 12-amino-acid segment, present in type s2 but not type s1 Helicobacter pylori VacA proteins, abolishes cytotoxin activity and alters membrane channel formation.

Helicobacter pylori, a gram-negative bacterium associated with gastritis, peptic ulceration, and gastric adenocarcinoma in humans, secretes a protein toxin, VacA, that causes vacuolar degeneration of epithelial cells. Several different families of H. pylori vacA alleles can be distinguished based on sequence diversity in the "middle" region (i.e., m1 and m2) and in the 5' end of the gene (i.e., s1 and s2). Type s2 VacA toxins contain a 12-amino-acid amino-terminal hydrophilic segment, which is absent from type s1 toxins. To examine the functional properties of VacA toxins containing this 12-amino-acid segment, we analyzed a wild-type s1/m1 VacA and a chimeric s2/m1 VacA protein. Purified s1/m1 VacA from H. pylori strain 60190 induced vacuolation in HeLa and Vero cells, whereas the chimeric s2/m1 toxin (in which the s1 sequence of VacA from strain 60190 was replaced with the s2 sequence from strain Tx30a) lacked detectable cytotoxic activity. Type s1/m1 VacA from strain 60190 formed membrane channels in a planar lipid bilayer assay at a significantly higher rate than did s2/m1 VacA. However, membrane channels formed by type s1 VacA and type s2 VacA proteins exhibited similar anion selectivities (permeability ratio, P(Cl)/P(Na) = 5). When an equimolar mixture of the chimeric s2/m1 toxin and the wild-type s1/m1 toxin was added to HeLa cells, the chimeric toxin completely inhibited the activity of the s1/m1 toxin. Thus, the s2/m1 toxin exhibited a dominant-negative phenotype similar to that of a previously described mutant toxin, VacA-(Delta6-27). Immunoprecipitation experiments indicated that both s2/m1 VacA and VacA-(Delta6-27) could physically interact with a c-myc epitope-tagged s1/m1 VacA, which suggests that the dominant-negative phenotype results from the formation of heterooligomeric VacA complexes with defective functional activity. Despite detectable differences in the channel-forming activities and cytotoxic properties of type s1 and type s2 VacA proteins, the conservation of type s2 sequences in many H. pylori isolates suggests that type s2 VacA proteins retain an important biological activity.

Animals↗
PubMed2001

Visual responses of neurons in the pretectal nucleus lentiformis mesencephali to moving patterns within and beyond receptive fields in pigeons.

Large-field patterns are effective stimuli for eliciting visual responses from neurons in the pretectal nucleus lentiformis mesencephali of nonmammals. The present study shows that stimulation beyond the receptive field does not contribute to the visual responses of neurons in the nucleus lentiformis mesencephali in two respects. First, changes in the direction and velocity of motion beyond the receptive field did not affect the visual responses of the pretectal cells to motion within the receptive field. Second, time differences in the onset of stimulation within and outside the receptive field did not influence the visual responses of the pretectal cells to motion in the receptive field, implying that there may be no long-range interaction between the receptive field and its surrounding field. The present study also indicates that the pretectal cells are not only sensitive to the direction and velocity of motion, but also to the size and density of dots in a random-dot pattern moving through the receptive field. Taken together with previous studies, these results suggest that the receptive field of the pretectal cells within the nucleus lentiformis mesencephali is large in size but well defined in boundaries, and that the pretectal cells respond to motion of visual stimuli within but not beyond their receptive fields.

Animals↗
PubMed2001

[The quantitative analysis of voice disease based on fractal method].

The fractal method is employed to check the voice diseases. The severity of pathological changes of human voice can be analyzed objectively and quantitatively with different fractal dimensions. With this method we can end up the history of judging the voice with subjective hearing and it is of great importance to the development of laryngology.

Fractals↗
PubMed2001

[The language healing system of deaf children based on wavelet transform].

In the language healing system of deaf children, the wavelet transform method is employed to describe the time-varying characteristics of speech signals, improve the resolution of speech spectrum and make the speech characteristics more obvious. The speech spectrum information shown in this system is easier for deaf children to observe and understand and it is of great importance to the language healing of deaf children.

Child↗
PubMed2001

[New progress of surface enhanced Raman spectroscopic studies on a gold electrode in a nonaqueous system].

Based on a highly sensitive new generation confocal microprobe Raman system, the adsorption behavior of thiocyanate (SCN-) on a gold electrode in methanol solution was investigated by SERS for the first time. Preliminary results demonstrated that the interaction between SCN- and the electrode is so strong that its SERS signal can be detected in the whole research potential region (-0.1 V(-)-1.4 V). The orientation change may occur in the potential range -0.6 V-0.7 V. From -0.1 V to -0.6 V SCN- is adsorbed mainly through S end onto Au surface while in the potential range of -0.7 V to -1.2 V it is oriented mainly through N end. The potential dependence of the Raman frequency of nu CN resulted in two different values of electrochemical Stark effect, suggesting the existence of molecular orientation change.

Electrochemistry↗
PubMed2000

[The relationship between clinical prognosis and classification of the isoforms of fuse gene in acute promyelocytic leukemia].

To check the anti-apoptosis gene bcl-2 protein/mRNA expression in 28 acute promyelocytic leukemia (APL), by immunohistochemistry and in situ hybridization, and to analyse the relationship among the bcl-2 gene expressions, clinical prognosis and classification of the isoforms of fuse gene in APL. The result shows the two types of isoforms of PML-RAR alpha have no significance in bcl-2 protein/mRNA expression, indexes of clinical prognosis. This shows that the classification of PML-RAR alpha isoform has no influence on clinical prognosis.

Adolescent↗