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Biomedical subjects

P Cao

Publications and source records attributed to P Cao.

At least 55 records · Page 3Linked to original sources
PubMed1999

Abdominal aortic aneurysms: current management.

Optimal management of abdominal aortic aneurysm (AAA) remains a challenging surgical problem. Over the last decade surgical and anesthetic improvements have provided perioperative mortality in the 2% range, when elective AAA repair was performed in single Institutions with large vascular experience. However, community- or national-based mortality rates for elective AAA surgery may be as high as 11% or more. Mortality rates associated with ruptured aneurysms remain as high as 90%. AAA prophylactic resection should be indicated when the risk of rupture exceeds the surgical risk. Although the risk of rupture correlates strongly with the diameter of the AAA, there is evidence that other factors can increase the rupture risk: hypertension, chronic pulmonary disease, aneurysm morphology, etc. Establishing a single threshold diameter for AAA repair appears naive. Moreover, AAA primarily affects older patients with other comorbidities that shorten life expectancy and increase perioperative risks: coronary artery disease, renal and pulmonary insufficiency, peripheral artery disease, etc. So that, proper management of individual AAA is based on balancing the perioperative risk, the risk of rupture, and life expectancy. In the subgroup of young healthy patients with additional risk factors for AAA rupture, elective repair at a smaller size (4 to 5.5 cm) may be beneficial if low surgical risk can be assured. In the last decade endovascular repair for AAA treatment has emerged. These less invasive endovascular techniques for AAA repair offer some advantages in terms of reduced patient stress, analgesic requirement, respiratory dysfunction, blood loss, need for intensive care and reduced hospitalization with an early technical success similar to that of open surgical treatment. However, there are no prospective, randomized studies evaluating endovascular treatment of AAA. Moreover, long-term results on the durability of these new techniques are needed to assess endovascular repair as an alternative treatment to prevent the risk of AAA rupture.

Aorta, Abdominal↗
PubMed1999

[Study of calcitonin gene methylation in chronic myeloid leukemia by using Hpa II-PCR].

To investigate the role of calcitonin(CT) gene hypermethylation in the transformation from the initial chronic phase to blast crisis of chronic myeloid leukemia, 31 CML patients were studied by using Hpa II-PCR. The results showed that the 10.52%(2/19) chronic phase, 71.4%(5/7) accelerated phase and 80.0%(4/5) blast crisis of patients had CT gene hypermethylation and that the increased methylation of the CT gene were related with the disease progression. The reports indicated that the hypermethylation of CT gene might be a useful marker for predicting the evolution of CML and selecting chronic phase patients for BMT.

Adolescent↗
PubMed1999

[Limited diffraction beams and its application].

Limited diffraction beams have a large depth of field and thus have many applications such as medical imaging, tissue characterization, material flaw detection and blood flow detection by Doppler method. Nondiffraction beams colud be produced only by transducer with an infinity large aperture in theory. The experimental results show that limited diffraction beams produced by a limited aperture have desirable large depth of field also. The theory of this kind of beams and their applications in field of medical imaging and blood flow estimation are introduced.

Acoustics↗
PubMed1999

[Omega-mercaptohexanoic acid self-assemble-modified gold electrode and its catalytic property for redox reaction of chlorophylls].

Omega-mercaptohexanoic acid (6-MHA) self-assemble-modified gold electrode has been made by the authors. The SERS spectrum and the variations of double-layer capacitance (Cd) which occurred in the formation of 6-MHA self-assembled monolayers (SAM) on gold electrode surface were studied. The structure model of this SAM was deduced. The results show that 6-MHA can form stable SAM on gold electrode, and this 6-MHA SAM electrode has obvious catalysis for the redox reaction of chlorophylls.

Caproates↗
PubMed1999

[Progress of surface enhanced Raman spectroscopic studies in nonaqueous systems].

In this report, we describe the applications and theoretical aspects of SERS phenomenon in nonaqueous systems, which mainly involves the structure of solid/nonaqueous system, the adsorption of some neutral and organic molecules, inorganic ions and other complex compound molecules, the process and mechanism of some electrochemical oxidation reduction reactions in organic solvents etc.. In this review, we also depict the similarities and differences in SER spectra of aqueous and non-aqueous systems.

English Abstract↗
PubMed1998

Capillary electrophoresis/electrospray ionization high mass accuracy time-of-flight mass spectrometry for protein identification using peptide mapping.

Capillary electrophoresis/electrospray ionization (CE/ESI) high mass accuracy time-of-flight mass spectrometry was used for the first time to characterize small proteins using peptide mapping. To identify small proteins, the intact proteins were first analyzed to obtain their average molecular weights with errors less than 1 Da. On-line capillary electrophoresis mass spectrometry of the tryptic digests of these small proteins was then performed to obtain the accurate molecular weights of the peptides with accuracies of approximately 10 ppm. Next, this information was used for the identification of the proteins using a protein database. It was found that high mass accuracy is an effective tool in reducing the list of most-likely proteins generated by the database. In addition, on-line collision-induced dissociation of the completely or partially resolved capillary electrophoresis peaks of the protein digests was used to unambiguously identify the sequences of these peptides. Each CE/ESI-MS analysis used only 5 nL of sample containing approximately 120 fmol of each peptide in protein digests. The results indicate that the combination of capillary electrophoresis and high resolution, high mass accuracy time-of-flight mass spectrometry is a viable option for the identification of small proteins using peptide mapping.

Calibration↗
PubMed1998

Pressure-assisted and pressure-programmed capillary electrophoresis/electrospray ionization time of flight-mass spectrometry for the analysis of peptide mixtures.

Pressure assisting and pressure programming the inlet of the capillary electrophoresis instrument were used for the analysis of peptide mixtures and protein digests using capillary electrophoresis/electrospray ionization-mass spectrometry (CE/ESI-MS). CE/ESI-MS of peptide mixtures and tryptic digests of proteins was studied using three different types of capillary columns: (i) a freshly aminopropylsilane (APS)-treated column, (ii) an untreated column, and (iii) a degraded APS-treated column. To maintain a constant and adequate buffer flow toward the CE capillary outlet for stable CE and ESI operation, low pressure was applied to the inlet of the CE when an untreated or degraded APS capillary was used. By programming the inlet pressure, CE/ESI-MS analysis time was reduced to 1/3 of its original time. The utility of this technique is demonstrated by CE/ESI-MS analysis of a hemoglobin variant (hemoglobin-S) and its tryptic digests. Identification of the mutant peptide in the tryptic digest of hemoglobin-S was achieved by collision-induced dissociation (CID) of the protein digests using CE/ESI time of flight-mass spectrometry (TOF-MS).

Amino Acid Sequence↗
PubMed1998

A randomized study on eversion versus standard carotid endarterectomy: study design and preliminary results: the Everest Trial.

PURPOSE: The EVEREST Trial was designed to determine whether the surgical technique influences the durability and complications of carotid endarterectomy (CEA). The current report focuses on the study design and preliminary results. METHODS: EVEREST is a randomized multicenter trial. A total of 1353 patients with carotid stenosis requiring surgical treatment were randomly assigned to received standard (n = 675) or eversion (n = 678) CEA. Primary end points included carotid occlusion, major stroke, death, and restenosis rate. RESULTS: The rate of perioperative major stroke and death (1.3 for each study group) and the incidence of early carotid occlusion (0.6% for eversion vs 0.4% for standard) were similar. No significant differences were found between eversion and standard CEA with respect to incidence of perioperative transient ischemic accident, minor stroke, cranial nerve injuries, neck hematoma, myocardial infarction, or surgical defects as detected with intraoperative quality controls. Clamping time was significantly shorter for eversion CEA compared with patch standard procedures (31.7 +/- 15.9 vs 34.5 +/- 14.4 minutes, p = 0.02). A shunt was inserted in 11% of patients undergoing eversion CEAs and in 16% of patients undergoing standard procedures. Overall 30-day events occurred in 13.3% of the eversion group and in 11.4% of the standard group (p = 0.3). At a mean follow-up of 14.9 months (range, 1 to 38 months), 16 (2.4%) restenoses occurred in the eversion group and 28 (4.1%) occurred in the standard group (odds ratio, 0.56; 95% confidence interval, 0.3 to 1.1; p = 0.08). CONCLUSION: The preliminary results of the EVEREST Trial suggest that eversion CEA is a safe and rapid procedure with low major complication rates. No significant differences in restenosis rates were observed between eversion and standard CEA at the available follow-up. Longer-term results are necessary to assess whether the eversion technique influences the durability of CEA.

Adult↗
PubMed1998

Analysis of peptides, proteins, protein digests, and whole human blood by capillary electrophoresis/electrospray ionization-mass spectrometry using an in-capillary electrode sheathless interface.

An in-capillary electrode sheathless interface was applied to the capillary electrophoresis/electrospray ionization-mass spectrometry (CE/ESI-MS) analysis of mixtures of small peptides, proteins, and tryptic digests of proteins. The effects of different experimental parameters on the performance of this CE/ESI-MS interface were studied. The distance of the in-capillary electrode from the CE outlet and the length of the electrode inside the capillary had no significant effects on the CE separation and ESI behavior under the experimental conditions used. However, significant enhancement of the sensitivity resulted from the use of narrower CE capillaries. Using a quadrupole mass spectrometer, an aminopropylsilane-coated capillary, and a wide scan mass-to-charge ratio range of 500-1400, detection limits of approximately 4, 1, and 0.6 fmol for cytochrome c and myoglobin were achieved for 75-, 50-, and 30-micron inner diameter capillaries, respectively. Approximately one order of magnitude lower detection limits were achieved under the multiple-ion monitoring mode. The application of the in-capillary electrode sheathless interface to real-world samples was demonstrated by CE/ESI-MS analysis of a human blood sample.

Amino Acid Sequence↗
PubMed1998

Role of surgical techniques and operative findings in cranial and cervical nerve injuries during carotid endarterectomy.

OBJECTIVE: To establish the incidence of cranial and cervical nerve injuries during CEA and their relationship to different surgical techniques and operative findings. DESIGN: A prospective study. PATIENTS AND METHODS: From January 1994 to April 1995, 187 consecutive patients undergoing 190 CEAs were evaluated. Pre- and postoperative cranial and cervical nerve assessments were carried out by a single otolaryngologist, blinded to the operative technique and findings. Deficits lasting more than 12 months were defined as permanent. Logistic regression analysis was performed to evaluate the influence of surgical technique, type of anaesthesia, neck haematoma, and plaque extension on the onset of nerve injuries. RESULTS: Postoperatively, nerve lesions were identified in 51 CEAs (27%) and non-neurological injuries (hemilaryngeal ecchymosis or oedema) causing postoperative dysphonia were present in 80 CEAs (42%). All non-neurological injuries were transient and 98% disappeared within 1 month of surgery. Thirteen (7%) nerve lesions were permanent, but none were disabling. Vagus nerve lesions were significantly associated with long (> 2 cm) carotid plaque (OR = 3.5; CI 1.09-12.37; p = 0.03). Cervical branch lesions were associated with the presence of neck haematoma (OR = 1.9; CI 0.7-4.7; p = 0.05). The incidence of single cranial nerve injuries was higher in patch (OR = 2.7) and eversion (OR = 1.9) procedures than in primary closure. Multiple deficits (2 or more) were most frequent in eversion CEAs (OR = 2.8) and in cases complicated by neck haematoma (OR = 3.8). CONCLUSIONS: Cranial and cervical nerve lesions during CEA are common. However, our data showed that the majority of local complications are related to transient hemilaryngeal ecchymosis or oedema and, when permanent, are neither clinically relevant nor disabling at 1 year of follow up. Carotid plaque extension and neck haematoma appear to increase the incidence of cranial and cervical nerve lesions during CEA.

Adult↗
PubMed1998

Extracellular release of antigenic proteins by Helicobacter pylori.

Screening a Helicobacter pylori genomic library with antisera raised against H. pylori broth culture supernatant resulted in the identification of six antigens: urease, HspB, Lpp20, DnaK, MsrA, and a cysteine-rich 28-kDa protein (designated HcpA). H. pylori antigens may be released into the extracellular space by multiple mechanisms, including specific secretion pathways, autolysis, and membrane vesicle formation.

Amino Acid Sequence↗
PubMed1998

[An experimental study of the formation of osteoclast-like cell in rat bone marrow culture].

OBJECTIVES: To set up a culture method of osteoclast-like cell (OLC) formation in rat bone marrow and to investigate the effects of 1,25(OH)2D3 and osteoblasts on the formation of OLC. METHODS: The culture of bone marrow from 4-week old rats were studied for the formation of OLC. The culture was divided into four groups: group A, only bone marrow culture as control; group B, bone marrow and osteoblast (from the crania of newborn rats) coculture; group C, bone marrow culture with 1,25(OH)2D3(final concentration 10(-8) mol/L); group D, bone marrow and osteoblast coculture with 1,25(OH)2D3. After 7 days of culture, the number of OLC which was recognized as tartrate resistant acid phosphatase (TRACP) (+) multinucleated cell, the cellular TRACP and the resorption pits on bone slice were examined. RESULTS: No OLC was present at the beginning of the bone marrow culture in any groups. OLC still failed to be detected in group A by the end of culture, and a few of OLCs could be found out in group B and C. The number of OLC in group D was more than that in the other groups (P < 0.01). The cellular TRACP in group A was lower than that in the other groups, and the cellular TRACP activity in group B and C was lower than that in group D (P < 0.01). In group D, several smaller resorption pits on The bone slice were observed. CONCLUSION: The formation of OLC requires 1,25(OH)2D3 and coculture with osteoblasts favors the formation of OLC in bone marrow culture.

Animals↗
PubMed1998

[The changes of electrogastrogram and gastrointestinal pressure following cholecystectomy].

OBJECTIVE: To investigate the mechanism and pathophysiological changes after abdominal surgery. METHOD: Twenty-two patients after cholecystectomy were selected to perform cutaneous electrogastrography (EGG) at least one hour before operation, and the first, the second and the third day after operation respectively. On the operative and postoperative days, gastroduodenojejunal manometry was performed in 17 of the 2 patients. RESULT: The percentage of EGG normal frequency on the operative day was obviously lower than that on the preoperative day (P < 0.001), and the percentage of bradygastria on the operative day was obviously higher than that on the preoperative day (P < 0.01). The postoperative EGG amplitude was obviously lower than the preoperative one (P < 0.001), and did not recover after three days. The phase III of the migrating motor complex (MMC) appeared within 24 hours after operation, and first appeared at the duodenum. MMC III was most vigorous at the duodenum in recording period, and was less at the antrum. The contractile power and the area of MMC III at antrum after operation were obviously lower than at duodenum and upper jejunum (P < 0.01). On the third day after operation, the contractile power was lower than normal (P < 0.01). CONCLUSION: Gastrointestinal motility dysfunction after cholecystectomy is related to EGG amplitude, and not to EGG frequency. The recovery of antrum MMC III is later than that of small bowl, resulting in delayed gastric emptying. The MMC III of small bowl resums in early period after abdominal surgery. Postoperative ileum is due the decrease of MMC III contractile power and the area after abdominal surgery, which represent the ability of gastrointestinal contraction.

Adult↗
PubMed1997

Identification of nonprotein amino acids from cycad seeds as N-ethoxycarbonyl ethyl ester derivatives by positive chemical-ionization gas chromatography-mass spectrometry.

Nonprotein amino acids from nine species of cycad seeds were analyzed as N-ethoxycarbonyl ethyl ester (ECEE) derivatives by positive chemical-ionization gas chromatography-mass spectrometry. Based on the retention times and mass spectrometry analyses, 12 nonprotein amino acids were identified in these seeds. In addition to the excitatory and putative neurotoxin beta-N-methylamino-L-alanine (BMAA), the known neurotoxin beta-N-oxalylamino-L-alanine (BOAA) was detected from the seeds of Macrozamia moorei and M. communis, and delta-N-oxalyl-ornithine was obtained from the Cycas revoluta seeds. A novel nonprotein amino acid named cycasindene, previously reported from C. revoluta, was also found in the seeds of members of the C. angulata and C. rumphii complex. Eight additional known nonprotein amino acids were also identified. This is the first report of the neurotoxin BOAA from cycad seeds.

Amino Acids↗