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Biomedical subjects

C Liu

Publications and source records attributed to C Liu.

At least 451 records · Page 25Linked to original sources
PubMed1998

Left to right extracardial shunt to control hemorrhage of ascending aorta and left ventricle: a report of 3 cases.

Presented in this paper are 3 cases of hemorrhage of ascending aorta and left ventricle after open heart surgery treated by extracardial bypass in our hospital from Oct. 1994 to Dec. 1995. Remained aneurysmal wall enclosing conduit graft was used as a sac bypassed to right atrium to form a extracardial left-to-right shunt in order to control bleeding and the results turned out to be satisfactory. The bypass and hemodynamically ignorable shunt can close spontaneously without complications with recovery of coagulation system. The technique may find wide application in clinical practice.

Adult↗
PubMed1998

Long-term expression and secretion of human glucocerebrosidase by primary murine and human myoblasts and differentiated myotubes.

Gaucher disease (GD) is caused by a deficiency in glucocerebrosidase (GC). Enzyme replacement for GD disease is effective but expensive and requires life-long treatment. Development of alternative therapeutic strategies is therefore important. One approach is an enzyme delivery system which could supply GC into the circulation continuously. We have previously reported that human GC cDNA in a retroviral vector (MFG-GC) efficiently transduced a murine myoblast line (C2C12) and expressed GC intracellularly and extracellularly. Now we have demonstrated that primary murine and human myoblasts are transduced at very high efficiency by MFG-GC (five to ten copies of human GC gene per cell at a multiplicity of infection of 5-10), 100% of MFG-GC transduced cells expressed human GC. The transduced primary murine and human myoblasts had an intracellular GC activities about five to ten times above nontransduced controls. Furthermore, transduced primary myoblasts secreted human GC extracellularly for up to 35 weeks in vitro. The secreted human GC is specifically taken up by bone marrow derived macrophages, the cell type most important to the pathogenesis of GD. These data suggest that transduced primary myoblasts may be useful in supplying GC as an alternative approach to the treatment of GD.

Animals↗
PubMed1998

Subtyping and characterization of D1S80 alleles in a Japanese population using PCR-RFLP.

In a Japanese population study of the D1S80 locus 24 alleles ranging from allele 16 to allele43 were analysed using PCR-RFLP. As two repeat units were found to contain the restriction cleavage site (CCAGG) for EcoRII, we digested the alleles with EcoRII, separated the digested fragments on polyacrylamide gels and stained with ethidium bromide. Of the 24 alleles 11 band patterns were identified and tentatively labeled E1 to E11. A total of 42 subtypes were detected in a population group of 111 unrelated individuals. All samples of allele 18 were of the E3 type, while about 60% of the allele24 samples were of the E4 type and about 40% were of the E8 type. The third most frequent allele (allele30) contained four types, E4, E8, E5 and E6. No deviations from Hardy-Weinberg equilibrium were observed. Since this method could differentiate those samples which had the same length but different sequences, it is quite useful for paternity testing and individual identification.

Alleles↗
PubMed1998

Surgical treatment of vesicoureteral reflux in infants under 3 months of age.

PURPOSE: Surgical treatment for vesicoureteral reflux (VUR) is controversial in infants, especially small infants because of technical difficulty and higher rate of spontaneous resolution. However, in some conditions, such as high-grade reflux, breakthrough infection, or severe renal scarring, early operation may be justified. This study is to evaluate the results of ureteral reimplantation in infants with VUR under 3 months of age. METHODS: From January 1993 to July 1997, 13 boys and five girls (24 ureters) under 3 months of age (range, 18 days to 3 months; mean age, 2 months) received ureteral reimplantation for VUR. The initial symptoms were urinary tract infection (UTI) in 16 infants, hydronephrosis found by prenatal ultrasound scan in one, and early postnatal screening ultrasound scan in one. The indications for 24 ureter reimplantations were high-grade reflux (grade V, n = 7), breakthrough infection under medical treatment (n = 5), and severe renal scarring (n = 8) and contralateral low-grade refluxing ureters (n = 4). All patients had Glenn-Anderson's or Cohen's ureteral reimplantation. Ureteral stents were required in six ureters. All patients had renal sonogram 1 month after operation to rule out ureteral obstruction. Fifteen patients had voiding cystourethrogram (VCUG) after operation. Renal growth was evaluated in 15 patients (20 reflux renal units) using serial ultrasound or differential perfusion renal scan. The operative time, use of ureteral stent, complication rate, hospital stay, and time needed for clearing urine, were compared with those of 115 counterpart patients at age over 3 months. Data were analyzed using X(2) test or t test. RESULTS: All patients, except one, were free of UTI during the follow-up of 6 months to 5 years. In fifteen infants who had postoperative VCUG, 14 were free of reflux, and one had persistent lower-grade VUR. One patient had transient ureteral obstruction that resolved spontaneously. One patient had postoperative ileus for 2 weeks. Renal growth of 20 reflux renal units was similar to that of the contralateral nonreflux kidneys. The only significant difference when compared with the patients over 3 months of age, was the higher incidence of ureteral stenting (25% v 4.2%, P<.01). CONCLUSIONS: Ureteral reimplantation should be performed in infants under 3 months of age when it is indicated.

Age Factors↗
PubMed1998

Involvement of protein kinase and G proteins in the signal transduction of benzophenanthridine alkaloid biosynthesis.

We have previously reported that elicitor-induced benzophenanthridine alkaloid biosynthesis in suspension-cell cultures of Sanguinaria canadensis L. (SCP-GM) is mediated by a signal transduction system that involves calcium and possibly protein kinase(s). In this work, a number of exogenous agents were employed to further investigate the components of the signal transduction pathway involved in the induction of alkaloid biosynthesis by a fungal elicitor and abscisic acid (ABA). SCP-GM suspension-cells were treated with compounds that modify protein kinase activity, including phorbol esters, and 1-oleoyl-2-acetyl-rac-glycerol (OAG), a synthetic diacylglycerol analogue. Phorbol-12-myristate-13-acetate induced alkaloid accumulation by as much as 65-fold over control values, while the negative control, phorbol-13-monoacetate, had no effect. OAG also increased alkaloid production by approximately 25-fold as compared to controls. Likewise, pretreatment of the suspension-cell cultures with H-7 or staurosporine, significantly suppressed ABA- or fungal-induction of benzophenanthridine alkaloid biosynthesis. Modulators of GTP-binding protein activity were also active in this system. Treatment of the suspension-cells with cholera toxin (CHX) induced alkaloid accumulation by 25-fold, which increased to 34-fold when CHX was combined with a fungal elicitor derived from Penicillium expansum (PE), and 32-fold when CHX was combined with ABA. Treatment of SCP-GM cells with CHX also enhanced the activities of two N-methyltransferases in the benzophenanthridine biosynthetic pathway namely, tetrahydroberberine-N-methyltransferase and tetrahydrocoptisine-N-methyltransferase, by six and seven fold, respectively. Furthermore, benzophenanthridine alkaloid biosynthesis was induced by treating the suspension-cells with the G-protein activators, mastoparan, mas-7 or melittin, while the inactive homologue, mas-17, did not. Suppression of alkaloid accumulation occurred when the suspension-cells were treated with GDP beta S or pertussis toxin prior to treatment of the SCP-GM cells with either PE or ABA. The results support the hypothesis that one or more protein kinases, and putative G proteins are involved in the signal transduction pathway that mediates ABA and fungal-induced benzophenanthridine alkaloid biosynthesis.

Abscisic Acid↗
PubMed1998

Interaction of the copper(II) macrocyclic complexes with DNA studied by fluorescence quenching of ethidium.

The fluorescence quenching of DNA bound ethidium ion by copper(II) macrocyclic complexes has been investigated. The binding constant indicates that the stable assembly can be formed between the DNA and the metal complex. The replacement of the fluorophore by the metal complexes results in a decrease of the ethidium moles intercalating to the molar DNA base pair and the binding constant of the ethidium to the DNA. The quenching of the ethidium excited state by the Cu(II) complex follows linear Stern-Volmer behavior. The quenching constant decreases regularly with an increase of the ratio of the concentration of the bound ethidium to that of DNA base pair. The dependence of the quenching constant on the ratio can be used to estimate binding constants for the fluorescent molecule and metal complexes to DNA. This method does not depend strongly on the type and the extent of interaction of metal complexes with DNA, allowing for the determination of binding constants for metal complexes that exhibit small changes in absorption spectra upon binding. The precision of this method will ultimately be governed by outstanding agreement between the quenching constant measured and that calculated by using a correlation function of the ratio or the DNA bound concentration of ethidium with quenching constant.

Animals↗
PubMed1998

Current trends in the management of head injury.

The importance of cerebral perfusion pressure (CPP) optimization has been recognized in the neurosurgical community in the United States as part of the recently published Guidelines for Management of Severe Head Injury. Although further basic and clinical research is needed before a CPP-directed head injury management standard of care is formulated, optimization of CPP is practical with present personnel and equipment resources in many emergency departments. Emergency Department physicians should be familiar with CPP management principles to facilitate interactions with neurosurgical colleagues and improve patient outcomes.

Cerebrovascular Circulation↗
PubMed1998

Postnatal changes of nicotinic acetylcholine receptor alpha 2, alpha 3, alpha 4, alpha 7 and beta 2 subunits genes expression in rat brain.

Postnatal changes of nicotinic acetylcholine receptor (nAChR) alpha 2, alpha 3, alpha 4, alpha 7 and beta 2 subunits mRNAs were investigated in rat brain using ribonuclease protection assay. Multiple developmental patterns were observed: (1) transient expression during the first few postnatal weeks; alpha 2 in the hippocampus and brain stem, alpha 3 in the striatum, cerebellum and cortex, alpha 4 in the hippocampus, striatum and cerebellum, alpha 7 in the cerebellum and beta 2 in the striatum. (2) Constant expression across development; alpha 2 and alpha 3 in the thalamus, alpha 4 in the cortex, thalamus and brain stem, alpha 7 in the thalamus and brain stem and beta 2 in all brain regions except striatum. (3) Non-detection across development; alpha 2 in the cortex, striatum and cerebellum. (4) Increase with age; alpha 7 in the cortex and hippocampus. (5) Bell-shaped development; alpha 7 in the striatum. Postnatal changes of nAChR isoforms in different brain regions of rat were investigated by receptor binding assays. The developmental patterns of [3H]epibatidine and (-)-[3H]nicotine binding sites were similar to each other in each brain region, but different from that of [3H] alpha-bungarotoxin binding sites. No obvious correlation was observed between the developmental patterns of [3H] alpha-bungarotoxin, [3H]epibatidine and (-)-[3H]nicotine binding sites and corresponding subunits mRNAs. These results indicate that multiple mechanisms are involved in changes of gene expression of nAChRs subunits in the brain of developing rats.

Animals↗
PubMed1998

Multiple gene expression analysis reveals distinct differences between G2 and G3 stage breast cancers, and correlations of PKC eta with MDR1, MRP and LRP gene expression.

A possible link between protein kinase C (PKC) and P-glycoprotein (P-gp)-mediated-multidrug resistance (MDR) was assumed from studies on MDR cell lines selected in vitro. The functional relevance of PKC for the MDR phenotype remains unclear, and the involvement of a particular PKC isozyme in clinically occurring drug resistance is not known. Recently, we have demonstrated significant correlations between the expression levels of the PKC eta isozyme and the MDR1 or MRP (multidrug resistance-associated protein) genes in blasts from patients with acute myelogenous leukaemia (AML) and in ascites cell aspirates from ovarian cancer patients. To extend these findings to further types of human tumours we analysed specimens from 64 patients with primary breast cancer for their individual expression levels of several MDR-associated genes (MDR1, MRP, LRP (lung cancer resistance-related protein), topoisomerase (Topo) II alpha/IIbeta, cyclin A and the PKC isozyme genes (alpha, beta1, beta2, eta, theta, and mu) by a cDNA-PCR approach. We found significantly enhanced mean values for MRP, LRP and PKC eta gene expression, but significantly decreased Topo II alpha and cyclin A gene expression levels in G2 tumours compared with G3. Remarkably, significant positive correlations between the MDR1, MRP or LRP gene expression levels and PKC eta were determined: MDR1/PKC eta (rs = +0.6451, P < 0.0001) n = 62; MRP/PKC eta (rs = +0.5454, P < 0.0001) n = 63; LRP/PKC eta (rs = +0.5436, P < 0.0001) n = 62; MRP/LRP (rs = +0.7703, P < 0.0001) and n = 62, MDR1/MRP (rs = +0.5042, P < 0.0001) n = 62. Our findings point to the occurrence of a multifactorial MDR in the clinics and to PKC eta as a possible key regulatory factor for up-regulation of a series of MDR-associated genes in different types of tumours.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

Nicotine exposure during a critical period of development leads to persistent changes in nicotinic acetylcholine receptors of adult rat brain.

Effects of neonatal nicotine exposure on the development of nicotinic acetylcholine receptor (nAChR) alpha2, alpha3, alpha4, alpha7, and beta2 subunit mRNAs and the number of nAChR isoforms in rat brain were studied. The mRNA levels for nAChR subunits were measured by ribonuclease protection assay, and the number of nAChR isoforms was measured with (-)-[3H]nicotine, [3H]epibatidine, and alpha-[3H]bungarotoxin ([3H]alpha-Bgt). Pups were divided into two groups: One group received (-)-nicotine treatment (0.1 mg/kg s.c. free base twice per day) during postnatal day (P)1 to P21 and the other during P8 to P16. The period from P8 to P16 was chosen due to persistent changes that occur in brain nAChRs and in the behavior of adult mice that received (-)-nicotine treatment during P10 to P16. (-)-Nicotine exposure from P1 to P21 significantly up-regulated the number of [3H]epibatidine and high-affinity (-)-[3H]nicotine binding sites in most of the brain regions studied but did not influence the number of [3H]alpha-Bgt binding sites. This effect was a transient one: The up-regulated binding sites returned to control level 1 week after withdrawal from nicotine. (-)-Nicotine exposure during P8 to P16 resulted in a significant and long-lasting increase in the number of nAChR isoforms labeled by (-)-[3H]nicotine, but not by [3H]epibatidine, in the cortex, hippocampus, and striatum of adult rat. This treatment converted the low-affinity binding sites of (-)-nicotine into a high-affinity state revealed by the competition studies of (-)-[3H]nicotine/(-)-nicotine. No changes in the mRNA levels of the subunits studied were observed following nicotine treatment during these two periods. These results suggest that the second postnatal week is a critical period during which nicotine treatment can induce permanent effects on the nAChRs in rat brain. The underlying mechanisms involved in the up-regulation of the number of nAChRs observed in this study are posttranscriptional.

Aging↗
PubMed1998

Interleukin (IL)-10, IL-12, and interferon-gamma production in primary and memory immune responses to varicella-zoster virus.

Varicella immunization provided the opportunity to examine the kinetics of interleukin (IL)-10, IL-12 and interferon (IFN)-gamma production elicited during primary in vivo sensitization with proteins of varicella-zoster virus (VZV), a common human herpesvirus. VZV-specific IFN-gamma release and T cell proliferation were elicited by immunization and persisted through 15 months of follow-up. The induction of VZV-specific T cells and IgG antibodies was accompanied by transient increases in IL-10 and IL-12 production. T cell proliferation to VZV was significantly lower in adults at 15 months than in vaccinated children or naturally immune subjects and correlated with lower IFN-gamma responses in individual vaccinees. After primary immunity was induced, continued IL-12 production was not necessary to maintain the predominant Th1-type response elicited by VZV. Cytokine profiles observed during primary in vivo sensitization to VZV suggest that parallel increases in IFN-gamma and IL-10 may be important in the induction of immunity to some viral pathogens.

Adolescent↗
PubMed1998

Clinical experience with orbicularis oculi myocutaneous flaps in the temporal area.

There are many methods to repair facial skin defects in clinical practice. The desired outcome for the surgeon and the patient is the restoration of facial appearance and function. The temporal region is one of the ideal donor sites for the repair of a facial skin defect, because this area is relatively inconspicuous and the skin quality is similar to that of the face. In the past, the temporal region was always used as the donor site of the local flap for repairing the facial skin defect. Because the blood supply of the skin comes from the subjacent tissue mainly rather than from the contiguous tissue, the pedicles of the local flaps are short, limiting the use of this area as a donor site. From 1993 to 1996, the anatomy of the orbicularis oculi myocutaneous flap in five cadavers was studied; what was learned allowed for the use of this flap to repair skin defects of the face in 13 patients. In this paper, the clinical experiences using the orbicularis oculi myocutaneous flaps to repair skin defects of the face and the surgical anatomy of this myocutaneous flap are discussed.

Adolescent↗
PubMed1998

A new principle for unilateral complete cleft lip repair, the lateral columellar flap method.

This article presents a different method for unilateral complete cleft lip repair. The tissue deficiency of the medial lip segment is filled with a flap from the lateral surface of the columella, which is in continuity with the lip segment. The lateral columellar flap and the medial lip segment are lowered in one piece vertically downward to such a position that the height of the arch of the Cupid's bow is equal on both sides. No lateral advancement is done. The suture line of the medial and lateral lip segments is an uninterrupted straight line, which imitates the natural line of the philtral column. The repaired lip has more fullness than the lips repaired with the conventional methods. The procedure is described in detail.

Cleft Lip↗
PubMed1998

Tomato phosphate transporter genes are differentially regulated in plant tissues by phosphorus.

Phosphorus is a major nutrient acquired by roots via high-affinity inorganic phosphate (Pi) transporters. In this paper, we describe the tissue-specific regulation of tomato (Lycopersicon esculentum L.) Pi-transporter genes by Pi. The encoded peptides of the LePT1 and LePT2 genes belong to a family of 12 membrane-spanning domain proteins and show a high degree of sequence identity to known high-affinity Pi transporters. Both genes are highly expressed in roots, although there is some expression of LePT1 in leaves. Their expression is markedly induced by Pi starvation but not by starvation of nitrogen, potassium, or iron. The transcripts are primarily localized in root epidermis under Pi starvation. Accumulation of LePT1 message was also observed in palisade parenchyma cells of Pi-starved leaves. Our data suggest that the epidermally localized Pi transporters may play a significant role in acquiring the nutrient under natural conditions. Divided root-system studies support the hypothesis that signal(s) for the Pi-starvation response may arise internally because of the changes in cellular concentration of phosphorus.

Amino Acid Sequence↗
PubMed1998

Characterizing output for the Varian enhanced dynamic wedge field.

The output factor for an enhanced dynamic wedge (EDW) field, like that for a dynamic wedge field, is a complex function of the field dimension in the wedge direction. The large change in output for different field sizes (varying more than 40% for a 60 degrees wedge angle) is due to rescaling of the golden segmented treatment table (GSTT), which specifies the cumulative monitor unit weighting as a function of moving jaw position. The rescaling of the GSTT results in increased output on the central axis with a decrease in the value of the final moving jaw position in the wedge plane. The output factor (in air or in water) on the central axis of an EDW field can be predicted to within 1% by multiplying the output factor (in air or in water) of an open field of the same size with the ratio of the normalized GSTT (NGSTT) value at 4.5 cm, which corresponds to a 10 cm x 10 cm square field, to the NGSTT value at the final moving jaw position for the EDW field. Once the NGSTT factor is separated from the output for EDW fields, the field-size-dependent wedge factor varies less than 1%. This approach allows a simple and accurate determination of the output factor for rectangular and asymmetric EDW fields. The equivalent square method for determining output for rectangular fields applies to EDW fields with the same precision as it does to open fields. The output for EDW fields strongly depends on the final moving jaw position. Every 5-mm change in the final moving jaw position causes 3.5-5.4% error in monitor unit calculation.

Calibration↗
PubMed1998

A quality assurance test tool for high dose-rate remote afterloading brachytherapy units.

A QA test tool is designed to quantitatively measure the HDR source positioning error, and to facilitate quick and dependable HDR timer linearity test and daily output constancy check. The test tool consists of two concentric disks. The lower disk has a cutout for inserting an HDR catheter, and the upper disk accepts a diode or miniature ionization chamber and can rotate relative to the lower disk. Ionization readings from the source (transferred to the center of the disks) are obtained at two rotational positions of the upper disk which houses the detector. The ratio of the readings is used to determine the source-positioning error of the HDR unit relative to the nominal source position by a simple triangulation principle. Experimental measurements confirm that the QA test tool is sensitive to approximately 0.2 mm variance in source positioning errors. In addition, the QA test tool is suitable for other common HDR QA tests such as the source travel step size test, the daily HDR unit output constancy check, and the timer linearity test. Its simple and robust design permits routine clinical use and provides a high confidence level in the accurate operation of HDR units.

Biophysical Phenomena↗