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Biomedical subjects

D Liu

Publications and source records attributed to D Liu.

At least 235 records · Page 13Linked to original sources
PubMed2000

Conjunctival incision for primary conjunctivodacryocystorhinostomy with Jones tube.

PURPOSE: To study a conjunctival incision approach for primary conjunctivodacryocystorhinostomy with Jones tube insertion. METHODS: This technique was applied throughout an 8-year period on 13 adult patients; each presented with complete lacrimal obstruction at the common canaliculus and excessive tearing. RESULTS: Surgical outcome was successful, with no external facial scarring. Follow-up ranged from 9 months to 7 years (median, 4.5 years). Complications included a tube exchange in one patient and occasional tearing in another. CONCLUSION: A conjunctival incision approach to conjunctivodacryocystorhinostomy (CDCR) with Jones tube insertion is an alternative technique for adult patients, especially those known (or potential) keloid-former cases, or those preferring not to undergo laser treatment and wanting to avoid an external facial scar.

Adult↗
PubMed2000

Bilateral orbital hemorrhage in a newborn.

PURPOSE: To report a case of severe bilateral proptosis resulting from orbital hemorrhage in a newborn and to discuss the differential diagnoses and management. METHOD: Case report of a 13-day-old male infant with bilateral proptosis since birth. The proptosis was monitored with clinical examinations and computed tomography as well as magnetic resonance imaging (MRI) scans, and it was managed with antibiotic ointment and patching. The MRI scans demonstrated bilateral subperiosteal orbital hemorrhage. RESULTS: Proptosis decreased, and there was successful, complete recovery without untoward sequelae in 14 days; follow-up indicated no late complications at age 1 year. CONCLUSION: Spontaneous orbital hemorrhage, unilateral or bilateral, is uncommon in an otherwise healthy newborn without apparent history of birth trauma. Magnetic resonance imaging scans are helpful in making the diagnosis of subperiosteal hemorrhage, and conservative management is advised.

Exophthalmos↗
PubMed2000

Isolated lung perfusion for patients with unresectable metastases from sarcoma: a phase I trial.

BACKGROUND: In patients with unresectable pulmonary metastases from sarcoma, systemic chemotherapy has had limited efficacy possibly because of dose-limiting toxicities. Isolated lung perfusion is an alternative method of delivering high-dose chemotherapy to the lungs while minimizing systemic toxicities. We present the results of our Phase I trial of isolated lung perfusion with doxorubicin hydrochloride in such a group of patients. METHODS: From May 1995 to June 1997, 8 patients with unresectable metastases from sarcoma limited to the lungs underwent isolated lung perfusion with doxorubicin. A dose-escalation schedule starting at 40 mg/m2 was used. Seven patients were treated with a dose of 40 mg/m2 or less, and 1 patient received 80 mg/m2. Blood, tumor, and normal lung samples were obtained at various time points during the operation. Patients were evaluated for cardiac, pulmonary, and other toxicities. RESULTS: The doxorubicin concentrations in both normal lung and tumor correlated directly with the amount of doxorubicin in the perfusate. The tumors took up less doxorubicin than the lung. All patients had minimal or undetectable systemic levels of doxorubicin at the conclusion of the perfusion. There were no cardiac or other systemic toxicities. In the 7 patients perfused with 40 mg/m2 or less of doxorubicin, there was a significant decrease in the forced expiratory volume in 1 second and a trend toward a significant decrease in diffusing capacity. The patient who received 80 mg/m2 underwent lung scanning postoperatively, and scans showed no ventilation or perfusion in the perfused lung. There were no perioperative deaths. Two patients are alive with disease, and 6 patients died of disease. The median follow-up is 11 months and the longest, 31 months. There were no partial or complete responses. One patient had stabilization of disease in the perfused lung, whereas the lesions in the untreated lung progressed markedly. CONCLUSION: Isolated lung perfusion is well tolerated by patients and effectively delivers high doses of doxorubicin to the lung and tumor tissues while minimizing systemic toxicities. A single dose of 80 mg/m2 resulted in substantial injury to the lung. There were no partial or complete responses in patients perfused with doxorubicin at the maximum tolerated dose of 40 mg/m2. Isolated lung perfusion remains a model for testing new and innovative therapies for metastatic sarcoma.

Adult↗
PubMed2000

Pulmonary artery perfusion with protective solution reduces lung injury after cardiopulmonary bypass.

BACKGROUND: The inflammatory response and higher temperature of lung tissue during cardiopulmonary bypass can result in lung injury. This study was to evaluate the protective effect of pulmonary perfusion with hypothermic antiinflammatory solution on lung function after cardiopulmonary bypass. METHODS: Twelve adult mongrel dogs were randomly divided into two groups. The procedure was carried out through a midline sternotomy, cardiopulmonary bypass was established using cannulas placed in the ascending aorta, superior vena cava, and right atrium near the entrance of the inferior vena cava. After the ascending aorta was clamped and cardioplegic solution infused, the right lung was perfused through a cannula placed in the right pulmonary artery with 4 degrees C lactated Ringer's solution in the control group (n = 6) and with 4 degrees C protective solution in the antiinflammation group (n = 6). Antiinflammatory solution consisted of anisodamine, L-arginine, aprotinin, glucose-insulin-potassium, and phosphate buffer. Plasma malondialdehyde, white blood cell counts, and lung function were measured at different time point before and after cardiopulmonary bypass; lung biopsies were also taken. RESULTS: Peak airway pressure increased dramatically in the control group after cardiopulmonary bypass when compared with the antiinflammation group at four different time points (24 +/- 1, 25 +/- 2, 26 +/- 2, 27 +/- 2 cm H2O versus 17 +/- 2, 18 +/- 1, 17 +/- 1, 18 +/- 1 cm H2O; all p < 0.01). Pulmonary vascular resistance increased significantly in the control group than in the antiinflammation group at 5 and 60 minutes after cardiopulmonary bypass (1,282 +/- 62 dynes x s x cm(-5) versus 845 +/- 86 dynes x s x cm(-5) and 1,269 +/- 124 dynes x s x cm(-5) versus 852 +/- 149 dynes x s x cm(-5), p < 0.05). Right pulmonary venous oxygen tension (PvO2) in the antiinflammation group was higher than in the control group at 60 minutes after cardiopulmonary bypass (628 +/- 33.3 mm Hg versus 393 +/- 85.9 mm Hg, p < 0.05). The ratio of white blood cells in the right atrial and the right pulmonary venous blood was lower in the antiinflammation group than in the control group at 5 minutes after the clamp was removed (p < 0.05). Malondialdehyde were lower in the antiinflammation group at 5 and 90 minutes after the clamp was removed (p < 0.01 and p < 0.05, respectively). Histologic examination revealed that the left lung from both groups had marked intraalveolar edema and abundant intraalveolar neutrophils, whereas the right lung in the control group showed moderate injury and the antiinflammation group had normal pulmonary parenchyma. CONCLUSIONS: Pulmonary artery perfusion using hypothermic protective solution can reduce lung injury after cardiopulmonary bypass.

Animals↗
PubMed2000

Hyperlipidemia.

Coronary heart disease (CHD) is prevalent and often related to an unhealthy diet and hyperlipidemia. The diagnosis of hyperlipidemia should be carefully made, using more than one measurement in the manner described. An assessment of risks allows one to decide whom to treat. Patients with CHD should be treated aggressively but it is less clear how aggressive to be with patients without CHD. Diet and exercise recommendations are appropriate for almost all patients. For those for whom the benefit is greater than the potential risks, statins are first-line drug therapy and they appear to have beneficial effects aside from their lipid-lowering properties.

Adult↗
PubMed2000

Supermotif peptide binding and degeneracy of MHC: peptide recognition in an EBV peptide-specific CTL response with highly restricted TCR usage.

We have investigated the presentation and CTL recognition of an HLA A*1101-restricted CTL peptide epitope AVFDRKSDAK (AVF)(3), derived from the EBV nuclear antigen (EBNA) 4, in the context of alleles belonging to the A3-supertype, A*0101, 0301, 1101, 3101, 3301, and 6801. The peptide binds to a A*6801 molecule as efficiently as to A*1101. The A*6801:AVF complex is recognized by some A*1101-restricted AVF- specific CTL clones. However, A*6801-positive (A*6801+) EBV-transformed lymphoblastoid cell lines (LCLs) are not killed by the same effectors. Furthermore, two A*6801+ donors did not mount an AVF-specific CTL response in vitro and lacked detectable AVF-specific effectors. Thus, this epitope is either subdominant, or non-immunogenic in the context of A*6801. These characteristics correlate with low stability of this MHC:peptide complex in living cells. We also demonstrate that a highly conserved AVF-specific TCR that dominates the AVF-specific CTL response in the majority of A*1101+ individuals recognizes the A*6801 molecule as a crossreactive alloantigen. Therefore, deletion of AVF-specific T cells may contribute to the non-immunogenicity or subdominance of the peptide in A*6801+ individuals.

Alleles↗
PubMed2000

Activity-regulated, cytoskeleton-associated protein (Arc) is essential for visceral endoderm organization during early embryogenesis.

Activity-regulated, cytoskeleton-associated protein (Arc) was first identified as an immediate-early gene regulated by synaptic activity. We have studied its functional role in vivo using a gene-targeting approach. We found that Arc is encoded by a single exon, and Arc mRNA is ubiquitously expressed in early mouse embryos. Homozygous Arc mutants are severely growth-retarded, fail to gastrulate and subsequently die before day 8.5 of embryogenesis. Further analysis revealed severe disorganization of visceral endoderm formation, and total separation and ectopic location of embryonic and extraembryonic structure. These findings demonstrate that Arc function is essential for early embryo development and patterning in mice, and support the hypothesis that signaling from visceral endoderm is essential for normal patterning of the extraembryonic and embryonic structure.

Animals↗
PubMed2000

Bending and fracture of compact circumferential and osteonal lamellar bone of the baboon tibia.

Lamellar bone is common among primates, either in the form of extended planar circumferential arrays, or as cylindrically shaped osteons. Osteonal bone generally replaces circumferential lamellar bone with time, and it is therefore of much interest to compare the mechanical properties and fracture behavior of these two forms of lamellar bone. This is, however, difficult as natural specimens of circumferential lamellar bone large enough for standard mechanical tests are not available. We found that as a result of treatment with large doses of alendronate, the lateral sides of the diaphyses of baboon tibia contained fairly extensive regions of circumferential lamellar bone, the structure of which appears to be indistinguishable from untreated lamellar bone. Three-point bending tests were used to determine the elastic and ultimate properties of almost pure circumferential lamellar bone and osteonal bone in four different orientations relative to the tibia long axis. After taking into account the differences in porosity and extent of mineralization of the two bone types, the flexural modulus, bending strength, fracture strain and nominal work-to-fracture properties were similar for the same orientations, with some exceptions. This implies that it is the lamellar structure itself that is mainly responsible for these mechanical properties. The fracture behavior and morphologies of the fracture surfaces varied significantly with orientation in both types of bone. This is related to the microstructure of lamellar bone. Osteonal bone exhibited quite different damage-related behavior during fracture as compared to circumferential lamellar bone. Following fracture the two halves of osteonal bone remained attached whereas in circumferential lamellar bone they separated. These differences could well provide significant adaptive advantages to osteonal bone function.

Journal Article↗
PubMed2000

Maternal care, hippocampal synaptogenesis and cognitive development in rats.

We report that variations in maternal care in the rat promote hippocampal synaptogenesis and spatial learning and memory through systems known to mediate experience-dependent neural development. Thus, the offspring of mothers that show high levels of pup licking and grooming and arched-back nursing showed increased expression of NMDA receptor subunit and brain-derived neurotrophic factor (BDNF) mRNA, increased cholinergic innervation of the hippocampus and enhanced spatial learning and memory. A cross-fostering study provided evidence for a direct relationship between maternal behavior and hippocampal development, although not all neonates were equally sensitive to variations in maternal care.

Animals↗
PubMed2000

Structural basis of DOTMA for its high intravenous transfection activity in mouse.

Eleven structural analogues of two known cationic lipids, N-[1-(2, 3-dioleyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTMA) and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride (DOTAP) were synthesized and utilized to evaluate the structural characteristics of DOTMA for its high intravenous transfection activity. Using a CMV-driven expression system and luciferase gene as a reporter, the transfection activity of these analogues was evaluated in mice using tail vein injection. Results concerning the structure-activity relationship with regard to the influence of the backbone, relative position between head group and the hydrophobic chains on the backbone, linkage bonds, as well as the composition of the aliphatic chains revealed that cationic lipids which give a higher in vivo transfection activity share the following structural characteristics: (1) cationic head group and its neighboring aliphatic chain being in a 1,2-relationship on the backbone; (2) ether bond for bridging the aliphatic chains to the backbone; and (3) paired oleyl chains as the hydrophobic anchor. Cationic lipids without these structural features had lower in vivo transfection activity. These structural characteristics, however, did not significantly influence their in vitro transfection activity. The contribution that cationic lipids make to the overall in vivo transfection activity is likely to be determined by the structure of DNA/lipid complexes and by the outcome of the interaction between the DNA/lipid complexes and blood components upon intravenous administration.

Animals↗
PubMed2000

Long-term expression of human alpha1-antitrypsin gene in mouse liver achieved by intravenous administration of plasmid DNA using a hydrodynamics-based procedure.

The liver is an important target organ for gene transfer due to its large capacity for synthesizing serum proteins and its involvement in numerous genetic and acquired diseases. Previously, we and others have shown that an efficient gene transfer to liver cells in vivo can be achieved by an intravenous injection of plasmid DNA using a hydrodynamics-based procedure. In this study, we systematically characterized the expression of transgene encoding a secretory protein in mouse. Using human alpha1-antitrypsin (hAAT) gene as a reporter, we demonstrate that the serum level of hAAT can reach as high as 0.5 mg/ml by a simple tail vein injection of 10-50 microg plasmid DNA into a mouse. The serum hAAT reaches the peak level 1 day after DNA injection and then declines during the following 2 to 4 weeks to 2-5 microg/ml, a level which persists for at least 6 months. Southern analysis of extracted DNA and RT-PCR analysis of RNA from the liver reveal that hAAT gene is active and present as episomal form after 6 months. These results suggest that the hydrodynamics-based transfection procedure provides a valuable tool for screening genes for therapeutic purposes in whole animals.

Animals↗