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Biomedical subjects

B Zhao

Publications and source records attributed to B Zhao.

250 records · Page 14Linked to original sources
PubMed1989

MR angiography and dynamic flow evaluation of the portal venous system.

We studied the value of MR angiographic techniques in imaging the portal venous system. Projection angiograms were created by postprocessing a series of two-dimensional, flow-compensated gradient-echo images. Flow velocity was determined by a bolus-tracking method with radiofrequency tagging and multiple data readout periods. Each image was acquired during a breath-hold. MR angiography was applied to six normal subjects and four patients with abnormal hemodynamics in the portal venous system. Flow velocity determined by MR was correlated with the results of duplex sonography. The main portal vein and intrahepatic branches were shown in all cases. Portosystemic collaterals were identified in all patients with portal hypertension. In normal subjects, peak flow velocities (17.9 +/- 2.8 cm/sec) on MR correlated well with values determined by duplex sonography (17.5 +/- 2.2 cm/sec) (r = .846, p less than .04). Reversed portal blood flow was shown in two patients. One patient with portal vein thrombosis had no evidence of flow by MR angiography. Our results indicate that MR angiography can provide a three-dimensional display of normal and abnormal vascular anatomy as well as functional information in the portal venous system.

Blood Flow Velocity↗
PubMed1986

Cloning full-length dengue type 4 viral DNA sequences: analysis of genes coding for structural proteins.

DNA sequences (approximately 11,000 nucleotides) representing the full-length genome of the dengue virus type 4 were cloned. The sequence of the first 2,429 nucleotides at the 5' terminus which includes the coding region for the structural proteins is presented. The virion structural proteins are encoded in one long open reading frame specifying a polyprotein precursor which is apparently proteolytically cleaved by a mechanism resembling that proposed for expression of structural proteins of other flaviviruses such as yellow fever (YF) and West Nile (WN) viruses. The N terminus for each of the dengue virus structural proteins was tentatively assigned by homology alignment to the corresponding sequence of YF or WN virus. Comparison of sequence homology of structural proteins suggests that dengue virus is more closely related to WN virus than to YF virus or Murray Valley encephalitis virus. Finally, analysis of the extreme 5'- and 3'-terminal nucleotides of the dengue virus genome revealed sequences that may be involved in transcription, replication, and packaging of viral RNA.

Amino Acid Sequence↗
PubMed1985

Cytochemical and ultrastructural studies of the Langerhans' cells. Sequential observations in experimental contact allergic reaction.

In the guinea pig, experimental allergic contact dermatitis (ACD) and primary irritant contact dermatitis (PICD) were induced with different concentrations of dinitrochlorobenzene (DNCB). The epidermal Langerhans' cells (LCs) were observed sequentially by both adenosine triphosphatase (ATPase) and electron microscopy. Light microscopically, in ACD, the density and dendritic processes of LC decreased markedly within 12 h after antigen challenge. Almost no recognization LCs could be seen within 2 to 5 days. Later, LCs began to repopulate in the epidermis. Within 14 days, the density and shape of the LCs returned to normal. On the contrary, LCs changed more rapidly in PICD. The dendritic processes of LC decreased within 2 h and cell density decreased dramatically within 6 h after DNCB application. LCs also repopulated more rapidly in the epidermis. Electron microscopically, in ACD, we observed that lymphocyte-like cells apposed to LCs; LCs were activated and damaged; however, in PICD, we found neither the apposition of lymphocyte-like cells to LCs, nor the activation of LCs. LCs play an important role in the convalescence phase as well as in the early and later phases of contact allergic reaction.

Adenosine Triphosphatases↗
PubMedDate not supplied

Neurodegeneration in Alzheimer disease. Is apoptosis involved?

Alzheimer disease (AD), the most common dementia of the elderly, results from a significant loss of neuronal cells in brain regions important in memory and cognition. Several lines of evidence suggest that the A beta peptide is directly responsible for some of this neuronal cell death. We review recent evidence from in vitro toxicity and immunohistochemical studies that suggest some of the cell loss in AD is the result of apoptosis.

Aged↗
PubMedDate not supplied

Human nails as a biomarker of arsenic exposure from well water in Inner Mongolia: comparing atomic fluorescence spectrometry and neutron activation analysis.

Arsenic (As) is found naturally in the geological strata within the Ba Men Region of Inner Mongolia, China. A study was conducted to compare the total As measurements from two analytical techniques: instrumental neutron activation analysis (INAA) and atomic fluorescence spectrometry (AFS), and to verify nails as an exposure biomarker in this population. In 1999, nail and water samples were collected in a pilot study. Fingernails and toenails were pooled from 32 participants and analysed for total As by both INAA and AFS. Mean nail As values were 14.8+/-2.4 and 19.4+/-2.8 microg g-1 (+/-SEM) for INAA and AFS, respectively. Results from these two methods were significantly correlated (r=0.93, p<0.0001). In 2000, a second study was conducted and INAA was used to measure total As in toenails from 314 Ba Men residents. Well water samples were collected from 121 households and analysed by AFS. A significant correlation was observed between toenail and well water As (r=0.84, p<0.0001). Based on the results, INAA was significantly correlated with AFS and proved to be a reliable measure of nail As levels. In this population, toenail samples are a useful internal As exposure biomarker from drinking water sources.

Adult↗
PubMedDate not supplied

Platelet activating factor-acetylhydrolase activity following chorionic villus sampling and amniocentesis.

OBJECTIVE: Platelet activating factor (PAF) is essential for embryonic development and is a potent vasodilator. It increases vascular permeability and stimulates prostaglandin E2 (PGE2) production. Platelet activating factor-acetylhydrolase (PAF-AH), the enzyme that degrades PAF, is synthesized by decidual macrophages. The aim of this study was to test the hypothesis that chorionic villus sampling (CVS) and/or amniocentesis might cause an increase in maternal PAF-AH activity. METHODS: Maternal plasma PAF-AH activity was evaluated before and after genetic amniocentesis (N = 13) and transcervical CVS (N = 29). A control group (N = 9) was evaluated to study the effects of venipuncture. RESULTS: Chorionic villus sampling caused a significant elevation in PAF-AH activity (P < .0005). No changes were noted in PAF-AH activity in the amniocentesis or the control group. CONCLUSIONS: Chorionic villus sampling causes subclinical release of PAF-AH, possibly from the decidual macrophages. Increased PAF-AH activity might result in decreased PAF levels, which might lead to vasoconstriction in the placental circulation due to lack of the vasodilator effects of PAF and possibly PGE2. This mechanism might explain the increased risk for fetal limb reduction noted with CVS performed at very early gestational ages.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMedDate not supplied

Significance of K-ras codon 12 point mutation in pancreatic juice in the diagnosis of carcinoma of the pancreas.

The significance of K-ras codon 12 point mutation in pancreatic juice in the diagnosis of carcinoma of the pancreas is still unclear. The aim of this study was to evaluate the significance of K-ras codon 12 point mutation in pancreatic juice in the diagnosis of carcinoma of the pancreas. All of the 78 reports written from 1988 to 1996 on K-ras point mutation of carcinoma, mucin-producing tumors, and hyperplastic epithelia of the pancreas in both surgical or autopsy specimens and pancreatic juice are reviewed. As results, in surgical or autopsy specimens, K-ras mutation was found in 81% of ordinary duct cell carcinoma and in 53% of mucin-producing tumor of the pancreas; this mutation was also found in hyperplastic epithelia in chronic pancreatitis (7%) and in autopsy cases without pancreatic diseases. In pancreatic juice, K-ras mutation was found in 72% of ordinary pancreatic carcinoma and in 53% of mucin-producing tumor, respectively. In conclusion, most previous reports have indicated that K-ras mutation in pancreatic juice is useful for a diagnosis of pancreatic carcinoma. However, since K-ras gene mutation was also detected in non-tumorous lesions, the diagnosis of pancreatic carcinomas is not necessarily correct if it is based solely on the detection of K-ras mutation in pancreatic juice. Future studies should focus on analyzing the amino acid sequence of K-ras mutation or the combination of this mutation with other parameters such as tumor markers in pancreatic juice, to enhance its specificity and accuracy.

Carcinoma↗
PubMedDate not supplied

A case report of cribriform carcinoma of the pancreas with long time survival.

A 62-year-old man had complained of left abdominal pain and tenderness and a body weight loss. Abdominal ultrasonography and computed tomography revealed homogeneous tumor with clear margin, and an irregular shape (3.5 x 2.0 cm) in the body of the pancreas. Endoscopic retrograde cholangiopancreatography showed a shadow defect in the main pancreatic duct adjacent to the tumor, which suggested intraductal tumor spread. Distal pancreatectomy with splenectomy and left paraaortic lymph node dissection was performed. Microscopically, the tumor showed microtubular carcinoma, which was characterized by a cribriform pattern, medullary growth, and little interstitium. The tumor was encapsulated by a relatively thick fibrous capsule. The patient was discharged uneventfully, and he is alive 33 months after operation without a distinct sign of recurrence. In conclusion, cribriform carcinoma of the pancreas has specific characteristics, such as good prognosis, expansive growth with little invasion, intraductal growth and spread without mucin production and histological marked cribriform pattern. This type of carcinoma should be classified as a new disease entity of carcinoma of the pancreas.

Carcinoma↗
PubMedDate not supplied

Study on Chinese common allergens of contact dermatitis.

Patch tests were performed according to the European Standard Allergens (ESA) in 204 cases suspected of contact dermatitis. The reaction was positive in 58.33% of the cases. The common allergens were nickel (15.7%), fragrance mix (11.8%) p-phenylenediamine (8.8%), colophony (6.9%), benzocaine (6.4%), formaldehyde (5.9%), black rubber mix (4.9%), cobalt (4.4%), balsam of Peru (3.9%), potassium dichromate (3.4%), thiuram mix (2.9%) and mercapto mix (2.9%). In 85 cases of negative reaction to the European Standard Allergens, 36 were patch tested to suspected agents based on the individual case histories, of which 21 positively reacted. The common sensitizing agents were ampicillin and thiomersal. Of 204 cases, 107 were cases of facial contact dermatitis. Patch tests showed that the most common allergens were p-phenylenediamine (15.9%), nickel (13.1%) and fragrance mix (14.95%).

Adolescent↗
PubMedDate not supplied

Appleby operation for carcinoma of the body and tail of the pancreas.

Long-term survival of carcinomas in the body and tail of the pancreas after surgery is still rare. One of the major reasons for unresectability is cancerous invasion to major vessels, such as the common hepatic and splenic arteries. Resection of the involved arteries can increase resectability and thus might increase post-operative survival. The aim of this study was to clarify the importance of the Appleby operation for carcinoma of the body and tail of the pancreas. A Case Report was carried out with a 54 year-old man, had suffered back pain and loss of body weight for six months. Imaging procedures such as US, CT or angiography showed a carcinoma in the body of the pancreas, about 3 cm in size, and both the common hepatic and splenic arteries were invaded by the tumor. The Appleby operation was used for this patient, since firstly there was no invasion to the head of the pancreas, secondly neither the proper hepatic artery nor the SMA was involved, thirdly the root of the CA was free of carcinoma, and finally because clear pulsation of the proper hepatic artery could be felt one or two minutes after occlusion of the CHA, which indicated that resection of the CHA would not lead to hepatic ischemia. The postoperative course was uneventful. His appetite recovered well and his body weight increased to the level before the disease. The patient was relieved from back pain and has returned to work 18 months after the operation, although he had a local recurrence eight months after the operation. In addition, eleven cases with carcinoma of the body and tail of the pancreas were used for a literature review. The average survival time after the Appleby operation is 6.6 months, and four patients are still alive. One patient has survived 13 years after the operation. It was concluded that although the prognosis after Appleby procedure is still not satisfactory that this operation can at least offer patients a better quality of life.

Back Pain↗