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Biomedical subjects

Z Ma

Publications and source records attributed to Z Ma.

At least 109 records · Page 6Linked to original sources
PubMed2000

Computer-aided 3-D reconstruction and measurement of the optic canal and intracanalicular structures.

OBJECTIVE: To reconstruct the human optic canal and its inner structures, and to provide detailed knowledge of this region for optic nerve decompression for further understanding on the pathologic mechanisms of indirect optic nerve injury. METHODS: Six optic canals and their inner structures were reconstructed using a computer-aided 3-dimensional reconstruction system. Quantitative measurement of the canal wall thickness, bony canal transverse area, optic nerve transverse area, dural sheath transverse area, subarachnoid space transverse area, and subarachnoid space volume were done by means of the computer morphometric analysis system. The detailed spatial relationship among intracanalicular structures were also carefully identified on the 3-D models. RESULTS: The thinnest portion of the canal was the middle part of the medial wall (0.45 +/- 0.35 mm) and the narrowest space was in the middle part of the optic canal (the transverse area was 18.21 +/- 2.50 mm2). The volume of subarachnoid space which can be considered the compensatory space for distention incurred by the hemorrhage, optic nerve edema, or hematoma was 21.16 +/- 4.31 mm3. At the cranial opening, the middle part and orbital opening, its transverse area was 4.45 +/- 1.12 mm2, 2.68 +/- 1.32 mm2 and 1.23 +/- 0.83 mm2, respectively. CONCLUSIONS: Since the compensatory space was limited, even a tiny amount of blood or swelling of the nerve may cause optic nerve compression. Because the narrowest space was in the middle part of the optic canal and the compensatory space for distention gradually decreases from cranial end to orbital end, the middle part and the anterior part of the optic canal and dural sheath are critical in optic nerve decompression.

Eye↗
PubMed2000

Hepatocellular adenoma and focal nodular hyperplasia: a series of 24 patients with clinicopathological and radiological correlation.

OBJECTIVE: To investigate two rare benign lesions, hepatocellular adenoma (HCA) and focal nodular hyperplasia (FNH), and evaluate differential diagnosis. METHODS: Twenty-four consecutive patients with presumed HCA and FNH were studied at the Liver Cancer Institute from January 1996 to May 1999. Preoperative assessment included clinical evaluation, symptoms and laboratory tests. New imaging techniques were prospectively appraised in addition to usual techniques. All had hepatic resections and follow-up. Histologic examination of surgical specimens was obtained in all cases. RESULTS: In every instance, FNH was an incidental finding. FNH consists of nodular aggregates of cytologically normal hepatocytes with foci of intranocular bile duct proliferation. In this series, patients with HCA had larger tumors and more often were symptomatic but the occurrence was unrelated to oral contraceptive steroids (OCS) usage. Intralesional hemorrhage or necrosis is common, and was seen in 75% of cases. The best imaging procedure in the diagnosis of FNH was MRI. Color Doppler US was a useful adjunct, but CT lacked specificity, making histological diagnosis mandatory. All patients underwent tumor resected were tumor--free during the follow-up. CONCLUSIONS: FNH is a distinct histopathologic entity, and is distinguishable from HCA. FNH is a hyperplastic response by the liver parenchyma to a pre-existing arterial malformation. HCA is a liver neoplasia and has the potential of malignant transformation to HCC. Based on these findings, we believe that if the clinical suspicion of HCA or FNH is strong, resection is usually the best approach if technically feasible and histologic diagnosis is mandatory.

Adenoma, Liver Cell↗
PubMed2000

[Diagnosis and treatment of bile duct tumor thrombus in patients with hepatocellular carcinoma].

OBJECTIVE: Tumor thrombus in the bile duct (BDT) is very rare in patients with hepatocellular carcinoma (HCC). The prognosis of the patients with BDT is very poor. To improve the prognosis, HCC patients with BDT were retrospectively reviewed. METHODS: Retrospective study was performed in 16 cases of HCC with BDT found in authors' institute from July 1987 to Oct. 1998. Factors affecting prognosis were analyzed. RESULTS: The occurrence rate of BDT as 0.76% (16/2100). Removal of BDT and HCC was performed in all but one patients. Fourteen patients were followed-up for over 1 year after operation. The 1-year survival and recurrence rate was 71.4% (10/14) and 57.1% (8/14), respectively. Three female patients survived over 4, 6, and 12 years, respectively. CONCLUSIONS: Early detection and diagnosis, surgical removal of primary tumors and BDT are the key points to prolong the survival time of patients.

Bile Duct Neoplasms↗
PubMed2000

[Pulmonary embolism due to deep venous thrombosis of extremities].

OBJECTIVE: To study the relationship between pulmonary embolism and deep venous thrombosis of extremities. METHODS: The authors conducted a retrospective analysis of 100 patients with deep venous thrombosis to analyse the occurrence of pulmonary embolism during 1996 to and 1998 in their hospital. RESULTS: In the 100 patients with deep venous thrombosis, the complication of pulmonary embolism was 45%, fatal pulmonary embolism was 4%. CONCLUSION: The complication of pulmonary embolism in the patients with deep venous thrombosis frequently occurred and medical professionals should pay attention to them.

Adult↗
PubMed2000

[Observation of therapeutic effect of Salviae miltiorrhiza and cytosine diphosphate-choline injection on patients with hypertensive cerebral hemorrhage].

OBJECTIVE: To assess the effect of Salviae miltiorrhiza (SM) injection in the treatment of hypertensive cerebral hemorrhage (HCH). METHODS: Fifty-one cases (age 50-78 years, 61.2 years on average) of HCH were randomly divided into three groups (SM + cytosine diphosphate-choline (CDP-C) group and para-aminomethyl benzoic acid (PAMBA) + CDP-C group as treated group, CDP-C group as control group) to observe the outcome of the clinical treatment, hematoma absorbability and changes of ADP-platelet agglutination rate (Pag), prothrombin time(PT) and function of the liver and kidney. RESULTS: The rate of good result (GR) and moderate disability (MD) in SM group was 85.71% with the method of Glasgow outcome score (GOS), others were 47.06% and 61.54% separately, they have significant difference, P < 0.05. Among them, SM group had best result. Compared the rate of hematoma absorbability of SM group with that of PAMBA, CDP-C groups, the difference was significant, P < 0.05. It did not affect the platelet coagulative function in SM group. CONCLUSION: SM injection could effectively improve the condition of patients with HCH, and without any side effect. It is worthwhile to be used in the clinical practice.

Aged↗
PubMed2000

[Pathological changes and protection of hypothalamus in pediatric craniopharyngioma].

OBJECTIVE: To understand the pathological changes of pediatric craniopharyngiomas so as to analyze its diagnosis, operative strategy and to prevent the damage of hypothalamus. METHODS: 189 cases of pediatric craniopharyngiomas treated from 1990 to 1998 were reviewed and analyzed via their CT, MRI, and surgery. RESULTS: 187 cases (98.9%) were cystic tumors, including 176 with calcification (93.1%); two cases were solid tumors (1.1%), and calcification occurred in only one. A gliosis layer between the wall of tumor and the hypothalamus was seen. CONCLUSION: Cystic change and calcification are the pathological features of pediatric craniopharyngiomas. There are some special relations between the tumors and stalk. These are the bases for total removal of pediatric craniopharyngiomas.

Adolescent↗
PubMed2000

[Anatomical basis of autonomic nerve-preserving radical resection for rectal cancer].

OBJECTIVE: To clarify anatomical basis of autonomic nerve-preserving radical resection for rectal cancer. METHOD: Of 10 cadavers, 4 were male and 2 female. Four had hemisected pelvis in the mid-sagittal plane without damaging the retrorectal anatomy. All stages of each dissection were recorded photographically. RESULTS: Hypogastric nerves were identified. The superior hypogastric plexus is the direct extension of the aortic plexus below the aortic bifurcation. It lies immediately behind the peritoneum and descends over the anterior surface of the 5th lumbar vertebra in the retroperitoneal tissue. The superior hypogastric plexus ends by bifurcating into the right and left hypogastric nerves. The two hypogastric nerves diverge from each other at about the level of the sacral promontory and run down and forward along the walls of the pelvis in the lamina of the pelvic fascia closest to the peritoneum. Both of them are strong fibres with white-grey and reticular appearance and well located just below and close to the aortic bifurcation. And after bifurcation each of them also gives rise to several branches. But it is difficult to identify the pelvic splanchnic nerves in complete samples. In mid-sagitted samples they take origin from the second to fourth sacral ventral rami just after the sacral nerves have emerged from the pelvic sacral foramina. They always form plexus at the lateral ligament and are crossed by middle rectal artery. CONCLUSIONS: It is not very difficult to preserve the hypogastric nerves to spare functions in resection for rectal cancer to the anatomical knowledge of the pelvic autonomic nerves. When the pelvic splanchnic nerves are to be preserved, dissection must be cautious at the level of the lateral ligment on the side of nerve-preservation. The operation should be performed near the rectum as close as possible to achieve functional preservation.

Autonomic Pathways↗
PubMed2000

[Study on clinical and molecular biological characteristics of infant acute leukemia].

OBJECTIVE: To study the clinical and molecular biological characteristics of infant acute leukemia (IAL). METHODS: R and/or G banding technique was used for analysis of karyotype. DNA blotting for HRX gene rearrangement, and polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) for fusion gene detection. RESULTS: Twenty cases of IAL were detected. HRX gene rearrangement was found in 10 cases, including HRX/AF-4 fusion gene in 5, HRX/AF-9 fusion in 2, and HRX/ENL fusion in 1, HRX self-fusion mediated by alu-repeat homologous recombination and HRX/EEN fusion each in one (HRX/EEN is a novel fusion gene reported for the first time). CONCLUSION: High frequency of HRX gene rearrangement occurred in IAL, which is characterised by a massive leukemia cell burden and 11q23 translocation, forming fusion genes, especially HRX/AF-4 (about 50%). The results are of important significance in guiding clinical treatment and approaching the etiology of IAL.

Acute Disease↗
PubMed2000

[Cloning of a new catechol 1,2-dioxygenase gene (tfd C) from Plesiomonas and its expression in the E. coli].

A new catechol-1,2-dioxygenase gene (tfd C) was cloned from the Plesiomonas using the PCR method. Primers were designed according to the reported sequence of Catechol-1,2-dioxygenase (C120) gene from Alcaligenes eutroplus. The amplified fragment contained a 765 bp open reading frame (ORF), encoding a protein of 255 amino acids. The new tfd C gene shared a high homology with the one cloned from Alcaligenes eutroplus, showing only one base difference at 693 site (C-->A) and consequently one amino acid difference at 228 site (P-->T). The ORF was cloned to the plasmid pBluescriptII KS, which was transferred to E. coli JM109 and a positive clone, pBt2G, was then selected. A significant activity of C120 was detected in the positive clone. When the ORF was cloned to the plasmid pET-30a, which was transferred to E. coli BL21(DE3) plysS, the expected 33 kD protein was detected from a positive clone, pET30A, by SDS-PAGE. The C120 is a key enzyme in degrading aromatic pollutants in the environment. In order to use plants to degrade aromatic pollutants, the gene will be introduced into the turfgrass. To express the gene properly in plants, its translation initiation codon was modified from GTG to ATG. A similar activity of C120 was obtained following the modification.

Amino Acid Sequence↗
PubMed1999

Synthesis and antimicrobial activity of 4H-4-oxoquinolizine derivatives: consequences of structural modification at the C-8 position.

The antibacterial 4H-4-oxoquinolizines were introduced recently to overcome bacterial resistance to fluoroquinolones. They exhibit potent antibacterial activity against Gram-positive, Gram-negative, and anaerobic organisms and are highly active against some quinolone-resistant bacteria including quinolone-resistant MRSA. Preliminary studies indicated that oxoquinolizines possess distinct activity and toxicity profiles as compared with their parent quinolones. In order to develop a potent antibacterial agent with the desired spectrum of activity, good tolerability, and balanced pharmacokinetic profile, we synthesized and evaluated a series of oxoquinolizines with various substituents at the C-8 position. Most compounds tested in this study demonstrated better activity against Gram-positive bacteria than ciprofloxacin and exhibited good susceptibility against ciprofloxacin- and methicillin-resistant S. aureus. While maintaining potent in vitro activity, several compounds showed improved in vivo efficacy over ABT-719 as indicated by the mouse protection test. As an example, the oral ED(50) values for the cis-3-amino-4-methylpiperidine analogue 3ss against S. aureus NCTC 10649M, S. pneumoniae ATCC 6303, and E. coli JUHL were 0. 8, 2.0, and 1.4 mg/kg, compared to 3.0, 10.0, and 8.3 mg/kg for ABT-719. The current study revealed that the steric and electronic environment, conformation, and absolute stereochemistry of the C-8 group are very important to the antibacterial profiles. Structural modifications of the C-8 group provide a useful means to improve the antibacterial activities, physicochemical properties, and pharmacokinetic profiles. Manipulation of the C-8 group also allows us to generate analogues with the desired spectrum of activity, such as analogues that are selective against respiratory pathogens.

Animals↗
PubMed1999

Optimization of throughput and desorbent consumption in simulated moving-bed chromatography for paclitaxel purification.

In simulated moving-bed (SMB) applications, throughput and desorbent consumption are two key factors that control process cost. For a given adsorbent volume and product purity requirements, throughput and desorbent consumption depend on desorbent composition, column configuration, column length to diameter ratio, and adsorbent particle size. In this study, these design parameters are systematically examined for paclitaxel purification. The results show that if adsorbent particle size, column dimensions and column configuration are fixed, the higher the product purity required, the lower the throughput. If product purity and yield are fixed, the larger the solute migration speed ratio, the higher the throughput, and the lower the desorbent consumption. If total bed volume and product purities are fixed, the longer the separation zones, the higher the throughput, but the higher the desorbent flow-rate. An intermediate configuration gives the minimum desorbent consumption. If there are no limits on pressure drop or zone flow-rate, the larger the column length to diameter ratio, the smaller the adsorbent particle size, the higher the throughput, and the lower the desorbent consumption. If the maximum zone flow-rate is controlled by the pressure drop limit and not by the standing waves requirement, the longer the columns, the lower the zone flow-rates and the lower the throughput. For 150 microns adsorbent particles and a maximum zone flow-rate of 300 ml/min, a design with optimal throughput and desorbent consumption is found for paclitaxel purification.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Studies of the role of group VI phospholipase A2 in fatty acid incorporation, phospholipid remodeling, lysophosphatidylcholine generation, and secretagogue-induced arachidonic acid release in pancreatic islets and insulinoma cells.

An 84-kDa group VI phospholipase A2 (iPLA2) that does not require Ca2+ for catalysis has been cloned from Chinese hamster ovary cells, murine P388D1 cells, and pancreatic islet beta-cells. A housekeeping role for iPLA2 in generating lysophosphatidylcholine (LPC) acceptors for arachidonic acid incorporation into phosphatidylcholine (PC) has been proposed because iPLA2 inhibition reduces LPC levels and suppresses arachidonate incorporation and phospholipid remodeling in P388D1 cells. Because islet beta-cell phospholipids are enriched in arachidonate, we have examined the role of iPLA2 in arachidonate incorporation into islets and INS-1 insulinoma cells. Inhibition of iPLA2 with a bromoenol lactone (BEL) suicide substrate did not suppress and generally enhanced [3H]arachidonate incorporation into these cells in the presence or absence of extracellular calcium at varied time points and BEL concentrations. Arachidonate incorporation into islet phospholipids involved deacylation-reacylation and not de novo synthesis, as indicated by experiments with varied extracellular glucose concentrations and by examining [14C]glucose incorporation into phospholipids. BEL also inhibited islet cytosolic phosphatidate phosphohydrolase (PAPH), but the PAPH inhibitor propranolol did not affect arachidonate incorporation into islet or INS-1 cell phospholipids. Inhibition of islet iPLA2 did not alter the phospholipid head-group classes into which [3H]arachidonate was initially incorporated or its subsequent transfer from PC to other lipids. Electrospray ionization mass spectrometric measurements indicated that inhibition of INS-1 cell iPLA2 accelerated arachidonate incorporation into PC and that inhibition of islet iPLA2 reduced LPC levels by 25%, suggesting that LPC mass does not limit arachidonate incorporation into islet PC. Gas chromatography/mass spectrometry measurements indicated that BEL but not propranolol suppressed insulin secretagogue-induced hydrolysis of arachidonate from islet phospholipids. In islets and INS-1 cells, iPLA2 is thus not required for arachidonate incorporation or phospholipid remodeling and may play other roles in these cells.

Animals↗
PubMed1999

Human pancreatic islets express mRNA species encoding two distinct catalytically active isoforms of group VI phospholipase A2 (iPLA2) that arise from an exon-skipping mechanism of alternative splicing of the transcript from the iPLA2 gene on chromosome 22q13.1.

An 85-kDa Group VI phospholipase A2 enzyme (iPLA2) that does not require Ca2+ for catalysis has recently been cloned from three rodent species. A homologous 88-kDa enzyme has been cloned from human B-lymphocyte lines that contains a 54-amino acid insert not present in the rodent enzymes, but human cells have not previously been observed to express catalytically active iPLA2 isoforms other than the 88-kDa protein. We have cloned cDNA species that encode two distinct iPLA2 isoforms from human pancreatic islet RNA and a human insulinoma cDNA library. One isoform is an 85-kDa protein (short isoform of human iPLA2 (SH-iPLA2)) and the other an 88-kDa protein (long isoform of human iPLA2 (LH-iPLA2)). Transcripts encoding both isoforms are also observed in human promonocytic U937 cells. Recombinant SH-iPLA2 and LH-iPLA2 are both catalytically active in the absence of Ca2+ and inhibited by a bromoenol lactone suicide substrate, but LH-iPLA2 is activated by ATP, whereas SH-iPLA2 is not. The human iPLA2 gene has been found to reside on chromosome 22 in region q13.1 and to contain 16 exons represented in the LH-iPLA2 transcript. Exon 8 is not represented in the SH-iPLA2 transcript, indicating that it arises by an exon-skipping mechanism of alternative splicing. The amino acid sequence encoded by exon 8 of the human iPLA2 gene is proline-rich and shares a consensus motif of PX5PX8HHPX12NX4Q with the proline-rich middle linker domains of the Smad proteins DAF-3 and Smad4. Expression of mRNA species encoding two active iPLA2 isoforms with distinguishable catalytic properties in two different types of human cells demonstrated here may have regulatory or functional implications about the roles of products of the iPLA2 gene in cell biologic processes.

Alternative Splicing↗
PubMed1999

Differential effects of jaundice and cirrhosis on beta-adrenoceptor signaling in three rat models of cirrhotic cardiomyopathy.

BACKGROUND/AIMS: Attenuated cardiac function has been reported in cirrhosis as well as in jaundice, but the mechanisms remain unclear. This study aimed to explore the differential effects of jaundice and cirrhosis on the heart. METHODS: Three rat models of cirrhosis were studied: chronic bile duct ligation, bile duct ligation followed by choledochojejunostomy to relieve jaundice, and a less jaundiced model induced by thioacetamide administration. Controls underwent a sham operation. Cardiac function was assessed by measuring isolated ventricular papillary muscle contractility. Cardiac beta-adrenergic receptor signaling was studied by measuring cAMP production stimulated at the receptor, G-protein, and adenylyl cyclase levels in the signaling pathway, using isoproterenol, aluminum fluoride and forskolin, respectively. RESULTS: Serum bilirubin and bile salt levels were markedly elevated in the bile duct-ligated group, moderately increased in the thioacetamide rats, and normal in the choledochojejunostomy and sham-operated controls. Papillary muscle contractile force after maximal beta-adrenergic receptor stimulation was decreased to a similar extent in all three cirrhotic models. In the bile duct-ligated and thioacetamide-induced cirrhotic rats, production of cAMP by all three drugs was significantly attenuated. However, the cAMP production in the choledochojejunostomy group was blunted only with isoproterenol and fluoride, and remained intact with forskolin stimulation. CONCLUSIONS: These results demonstrate that cirrhosis per se impairs cardiac function by attenuating the portion of the beta-adrenergic receptor signaling pathway upstream of adenylyl cyclase. Furthermore, significant jaundice and/or cholemia can inhibit adenylyl cyclase, which may contribute to blunted cardiac contractility in jaundiced patients.

Animals↗
PubMed1999

Temporary migration and regional development in China.

"A new approach to migration in developing countries is used in this paper, which integrates into the migration process the experiences of moving to cities, working in urban areas, and returning to the countryside. As a result, rural labor migration is directly linked to rural development through remittances, as well as through physical and human capital brought back by return migrants. Migration information is mainly drawn from China's 1995 1% National Population Survey.... It has been found that patterns of temporary migration are mainly shaped by the magnetic force of the growth-pole region. Job opportunities created there in labor-intensive industries have attracted large numbers of migrants, first from the surrounding rural areas and then from the peripheral regions, enhancing migration propensity in both areas."

Asia↗
PubMed1999

Computer-aided three-dimensional reconstruction and measurement of the optic canal and intracanalicular structures.

OBJECTIVE: To reconstruct the human optic canal and its inner structures and to provide detailed knowledge of this region for optic nerve decompression. METHODS: Six optic canals and their inner structures were reconstructed using a computer-aided three-dimensional reconstruction system. Quantitative measurement of the canal wall thickness, bony canal transverse area, optic nerve transverse area, dural sheath transverse area, subarachnoid space transverse area, and subarachnoid space volume was done using the computer morphometric analysis system. The detailed spatial relationship among intracanalicular structures was also carefully identified on the three-dimensional models. RESULTS: The thinnest portion of the canal was the middle part of the medial wall (0.45 +/- 0.14 mm) and the narrowest space was in the middle part of the optic canal (the transverse area was 18.21 +/- 1.20 mm2). The volume of subarachnoid space that can be considered the compensatory space for distention incurred by the hemorrhage, optic nerve edema, or hematoma was 21.16 +/- 4.31 mm3. At the cranial opening, the middle part, and the orbital opening, its transverse area was 4.45 +/- 0.46 mm2, 2.68 +/- 0.54 mm2, and 1.23 +/- 0.34 mm2 respectively. CONCLUSIONS: Because the compensatory space was limited, even a tiny amount of blood or swelling of the nerve may cause optic nerve compression. Because the compensatory space for distention gradually decreases from cranial end to orbital end, the middle part and the anterior part of the optic canal and dural sheath are critical in optic nerve decompression.

Adult↗
PubMed1999

Islet amyloid polypeptide and insulin relationship in a longitudinal study of the genetically obese (ob/ob) mouse.

Obese mice (Umeå ob/ob) and their lean litter-mates were investigated from 7 to 52 weeks of age with respect to the plasma concentration of islet amyloid polypeptide (IAPP) and insulin. Plasma levels of IAPP were highly elevated in the ob/ob mice and remained unchanged until age 33 weeks, after which a sudden significant increase occurred at age 40 weeks. The plasma concentration of insulin gradually increased from start to end and reached extremely high levels. In the lean mice, there were no age-related differences in plasma levels of IAPP and insulin, being of the same magnitude as in normal NMRI mice. The plasma IAPP/insulin molar ratio was similar in lean and obese mice until age 14 weeks. At 21 weeks, the ratio in the ob/ob mice had decreased dramatically and remained markedly (sixfold) lower than in the lean mice until the end of the study. The IAPP concentration in the pancreata of 21-week-old ob/ob mice was 25-fold higher than that in the lean mice. Immunohistochemically, a majority of the ob/ob mice displayed enlarged and more numerous pancreatic islets, compared with the lean mice, and the IAPP- and insulin-labeling intensity was equal for all animals. At the electron-microscopic level, there was an increase in the number of IAPP- and insulin-immunoreactive gold particles per whole granule area as well as per core granule area. We conclude that the dramatically increased IAPP levels in severely hyperinsulinemic ob/ob mice may be of importance for the development of insulin resistance. Further, the disproportionate secretion of IAPP and insulin in the adult obese mouse might indicate a disturbed negative feedback effect of IAPP on insulin secretory mechanisms, resulting in very high plasma insulin levels.

Aging↗