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Biomedical subjects

Z L Li

Publications and source records attributed to Z L Li.

At least 55 records · Page 3Linked to original sources
PubMed1995

Bone-bonding behavior under load-bearing conditions of an alumina ceramic implant incorporating beads coated with glass-ceramic containing apatite and wollastonite.

Alumina ceramic with a porous surface coated with glass-ceramic containing apatite and wollastonite (AW-GC) was implanted in a state of press-fit under load-bearing conditions in the femoral condylus of the mongrel dog and compared with a non-glass-ceramic-coated alumina ceramic. A trapezoid alumina ceramic implant (7 x 10 x 5 mm) with a lateral recess (0.9 mm deep) coated with alumina ceramic beads (mean diameter, 750 microns) in a single layer was prepared. The alumina ceramic beads were bonded to the alumina ceramic substratum using an identical alumina binder. The thickness of coating was 10-50 microns (mean, 30 microns). The surface of the beads and the substratum of the alumina implant were coated with AW-GC. A pull-out test and histologic examination were performed at 4, 8, and 24 weeks after implantation. The interfacial shear load was significantly increased from 8 to 24 weeks in both groups. The shear load of the glass-ceramic-coated implant was significantly greater than that of the noncoated implant at every stage. The interface shear load of the noncoated implant was 12.13 +/- 2.76 kg at 4 weeks, 13.92 +/- 4.18 kg at 8 weeks, and 24.17 +/- 5.17 kg at 24 weeks after implantation. The interface shear load of the glass-ceramic-coated implant was 17.96 +/- 2.81 kg at 4 weeks, 24.92 +/- 9.87 kg at 8 weeks, and 34.83 +/- 4.12 kg at 24 weeks after implantation. Histologic examination showed more ingrown bone tissue in the glass-ceramic-coated implants. It is suggested that AW-GC stimulated the bone ingrowth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Bone formation and remodeling around implanted materials under load-bearing conditions.

Bone formation and remodeling around implanted materials are influenced by the load-bearing conditions. In this study, three types of material were implanted into dog femoral condyles and bone formation and remodeling were observed for 24 weeks thereafter. Even thickening of lamellar bone was observed around bead-coated alumina implants, whereas thick fibrous tissue surrounded by corticalized bone formed around those made of smooth alumina. With an implant made of an artificial osteo-chondral composite material, abundant bone ingrowth into the titanium fibers was observed 8 weeks after the operation and this ingrowth resulted in firm attachment of this composite material to the host bone site. The tibial joint surface against the polyvinyl alcohol (PVA)-hydrogel articular surface of this implant remained intact, which suggests this artificial osteochondral composite material is a very promising joint prosthetic material.

Animals↗
PubMed1994

[Pharmacological studies of nin jion pei pa koa].

The results showed that King To Nin Jiom Pei Pa Koa had significant cough relieving and sputum removing effects. It also had an evident effect on relieving asthma in vivo and in vitro. In four acute or sub-acute inflammatory models, the anti-inflammatory effect was marked.

Animals↗
PubMed1994

[Accelerated thrombolysis by liposomal-encapsulated urokinase in a canine model of acute myocardial infarction].

We prepared liposomal-encapsulated urokinases (LEUK) by detergent removal technique. The encapsulated efficiency of urokinase (UK) was 25.6%. The LEUKs were neutral large unilamellar vesicles and its average diameter was 60.4 +/- 13.6 nm under electron microscope. Measurements of UK activity indicated about 7.1% loss of activity or leakage in tris-buffered saline over a 48 hr period at a temperature of 4 degrees C. After the same time incubation of LEUK and UK in human platelet-poor plasma (PPP) at 37 degrees C, the percentage of UK activity in LEUK group was remaining higher than that of UK group (30 min: 84.3 +/- 3.0% to 46 +/- 4%; 60 min: 60 +/- 5% to 14.9 +/- 0.8%, P < 0.01). These results suggest that liposomes preserve the thrombolytic potential of UK and that the half-life of UK in liposomes prolongs more than two times. Canine model of acute myocardial infarction was based on a thrombos obstruction. Thrombolysis tests were compared for LEUK and UK (n = 5). The time for restoring vessel patency reduced more than 50% when compared with that in UK group (28 +/- 7 min to 69 +/- 7 min, P < 0.01). The total dosage of LEUK was correspondingly lower. After one-hour thrombolysis, the fibrinogen of LEUK group (g/L) was considerably higher than that of UK group (2.5 +/- 0.5 to 1.6 +/- 0.4, P < 0.01). These results suggested that LEUK may be of practical significance in accelerating thrombolysis and reduction in bleeding complications.

Animals↗
PubMed1994

Screening of Epstein-Barr virus early antigen expression inducers from Chinese medicinal herbs and plants.

Ether extracts of 1693 Chinese medicinal herbs and plants from 268 families were studied for the induction of Epstein-Barr viral (EBV) early antigen (EA) expression in the Raji cell line. Fifty-two from 18 families were found to have inducing activity. Twenty-five and seven of them were from Euphorbiaceae and Thymelaeaeeae, respectively. Some of them, such as Croton tiglium, Euphorbia kansui, Daphne genkwa, Wikstroemia chamaedaphne, Wikstroemia indica, Prunus mandshurica Koehne and Achyranthes bidentata are commonly used drugs. The significance of these herbs in the activation of EBV in vivo and their relation to the development of nasopharyngeal carcinoma were discussed.

Antigens, Viral↗
PubMed1994

[An experimental study of the mechanism of shock-induced enterogenic infection after long-term standard total parenteral nutrition].

In this study, gnotobiotic rats were subjected to total parenteral nutrition (TPN) and subsequent hemorrhagic shock to study the mechanism of enterogenic infection in these circumstances. (1) Long-term (8-12 days) TPN induced impairment of gut barrier function, evidenced by atrophy of intestinal mucosa, significant decrease in diamine oxidase activity of intestinal mucosa and blood, and marked micro-ecologic imbalance of the intestinal mucosa flora with dominant growth of aerobes and relative decrease in anaerobes. The degree of mucosal damage were proportional to the duration of TPN. (2) In TPN+shock groups, further damage was found in the mucosa, with a large number of invading gram-negative organisms and a significant decrease in DAO activity as compared to that with TPN only groups. These changes were significantly correlated with enhanced bacterial translocation, elevation of LPS and MDA levels in the plasma. These findings suggested that long term TPN impairing gut barrier function, precipitated posttraumatic gut barrier failure. The determination of plasma DAO activity may help in the early diagnosis of gut injury during TPN and after trauma.

Actinomycetales Infections↗
PubMed1994

The effect of Isoptin SR on blood pressure, heart function and hypertrophy of left ventricle of hypertensive patients.

Isoptin SR was used in 65 essential hypertensive patients. 240mg Isoptin SR (German Knoll Pharmaceutical company) per day was used in group A (35 cases) for 6 weeks, and in group B (30 cases) for 24 weeks, BP in group A and B decreased obviously in the first and second week after treatment. Marked effective rate and total effective rate were 65.7% and 74.3% respectively in group A, and 70.0% and 83.3% in group B. There were no significant changes of HR in group A before and after treatment while there was a decrease of HR in group B (P < 0.001). Left atrium (LA) decreased after 6 weeks in group A with an obvious increase of E/A ratio. There was significant decrease in LA, increase in E/A ratio, regression of IVS, LVPW and LVMI, but no changes in SV, CO, LVEF after 24 weeks of treatment of Isoptin SR in group B. E/A ratio was very sensitive and occurred earliest both in group A and group B. Side effects such as headache, dizziness, constipation, insomnia, peripheral oedema, sinus bradycardia occurred mainly in the first week of treatment. These symptoms disappeared gradually in the course of continued administration of Isoptin SR.

Adult↗
PubMed1994

[Postlaminectomy kyphosis of the cervical spine complicating spinal cord tumor in the foramen magnum].

Postlaminectomy kyphosis is rarely encountered as a sequela of decompression of the upper cervical spine, especially in adults. We present a case of disabling cervical kyphosis which developed after laminectomy for excision of a foramen magnum tumor and was treated successfully by occipito-vertebral fusion. A sixty-one-year old female was treated by laminectomy of the first through to the third cervical spine for a foramen magnum meningioma. One year later, the laminectomy was extended downward to include the fourth through to the seventh cervical spine because of neurological deterioration. Seven years after the first laminectomy, she was referred to our spinal service because of severe neck pain, numbness and muscle weakness of both upper extremities. Lateral X-ray of her cervical spine presented a severe kyphosis. Roentgenogram two months after the first laminectomy already showed slight deformity and, timewise, it corresponded with the time when the patient experienced neurological deterioration. Subsequent X-rays showed progression of kyphosis. After we confirmed a lessening of the pain and improvement of the neurological symptoms during an axial traction using a halo-vest, posterior occipito-cervico-thoracic fusion was performed using Luque segmental spinal instrumentation and autogenous bone graft. After surgery the pain decreased and neurological symptoms improved. It is important to be aware of the complication of kyphotic deformity after laminectomy and once it has developed, it is recommended to stabilize the progression by early spinal fusion.

Cervical Vertebrae↗
PubMed1993

The isolation and structural elucidation of four novel triterpene lactones, pseudolarolides A, B, C, and D, from Pseudolarix kaempferi.

Four novel triterpene lactones, pseudolarolides A [1], B [2], C [3], and D [4], were isolated from the seeds of Pseudolarix kaempferi. Their structures and stereochemistry were elucidated from spectral data. Compound 2 shows potent cytotoxicity against three human cancer cell lines, KB (nasopharyngeal), A-549 (lung), and HCT-8 (colon), and against a murine leukemia cell line (P-388) with ED50 values of 0.49, 0.67, 0.73, and 0.79 micrograms/ml, respectively.

Animals↗
PubMed1993

[Effects of processing on special toxicity and pharmacodynamics in semen Armeniacae amarum].

The ethereal extract and decoction from raw Semen Armeniacae Amarum were found to induce EBV-EA activation in Raji cells cultured in vitro. Experiments show that both the extract and decoction have tumor-promoting activities, but the EBV-EA activation can be decreased by three kinds of processing-parching, scalding or parching after scalding, of which parching and parching after scalding are better. Moreover, parching after scalding is the best to enhance the relaxing of bowels, inactivate the amygdalase and increase the decoction rate of amygdalin.

Amygdalin↗
PubMed1993

Preliminary fluorimetric screening of fourteen palladium complexes as potential antitumor agents.

Making use of the fact that the combination of a drug substance with DNA may inhibit the duplication, synthesis and proliferation of DNA and the consistency of the in vivo and in vitro interactions, the authors worked out a preliminary screening method for testing complex agents as potential antitumor drugs using ethidium bromide as a fluorescence probe. In this report, the method was applied for in vitro testing fourteen synthesized palladium(II)/phenanthroline/amino acid/chloride complexes as potential non-platinum antitumor agents. The fluorimetric screening method was compared with methylene blue tube test and trypan blue dye exclusion assay. All three methods gave agreeable results. Among the complexes tested, [Pd(phen)(lys)]Cl, [Pd(phen)(arg)]Cl and [Pd(phen)(pro)]Cl showed antineoplastic ratios for animal tumor S-180 56%, 50% and 48%, respectively, in accordance with the order of their binding constants with DNA, 7.96 x 10(6), 4.52 x 10(6) and 1.0 x 10(6), respectively. The test results show that fluorimetric method is simple, cheap and rapid, suitable for preliminary screening of antitumor complexes.

Animals↗
PubMed1993

Preliminary screening of non-platinum complexes of Schiff bases as antitumour agents using fluorimetry.

Based on the consistency of the in vivo and in vitro interactions of drugs with DNA, a fluorimetric method has been developed as a new in vitro method for preliminary screening of antitumour agents. This method was tested using Schiff bases synthesized from salicylaldehyde with 1-alanine, 1-asparagine and 1-histidine, and complexes of these Schiff bases with Cu(II), Zn(II), Ni(II) and Sn(IV) as potential antitumour agents. The study of the interaction of the complexes with DNA by a fluorescence probe ethidium bromide (EthBr)-DNA system indicated the parallelism between the binding constants and antineoplastic ratios. The relationship between structure and antitumour activity was investigated.

Animals↗
PubMed1992

Dominantly inherited cystoid macular edema. A histopathologic study.

BACKGROUND: Dominantly inherited cystoid macular edema was described as a clinically distinct form of macular dystrophy with an onset at approximately age 30 years with slow progression over the ensuing decades. This is the first report of the light and electron microscopic findings in two donor eyes of one of the patients with this clinical entity. METHODS: Both eyes were obtained after death and fixed within 24 hours in a buffered 4% formaldehyde-1% glutaraldehyde solution. For light microscopy, tissue was embedded in paraffin and stained with hematoxylin-eosin, periodic acid-Schiff, colloidal iron for mucopolysaccharides, and an antibody to glial fibrillar acidic protein. For ultrastructural investigation, several blocks of choroidal/retinal tissues from the posterior pole, including both maculae, were embedded in epoxy resin and processed for transmission electron microscopy. RESULTS: Major findings included large retinal cysts in the macula, atrophy and marked disorganization of the inner nuclear layer, advanced degeneration of Müller cells with nodular aggregates of basement membrane-like material, and a preretinal membrane. The retinal vasculature did not show excessive endothelial alterations but was surrounded by deposits of multilayered basement membrane in the perivascular space. CONCLUSION: The authors believe that the pathologic features of dominantly inherited cystoid macular edema are different from those of macular edema caused by other disease processes. The predominant pathologic changes affected mainly the inner nuclear layer. The possibility of a primary disease of the Müller cell is suggested.

Aged↗
PubMed1992

Expression of a partial synthetic human TNF cDNA in E. coli.

A recombinant human tumour necrosis factor (rhTNF) cDNA was constructed. The TNF gene was isolated from a human genomic gene library. There are four exons in the TNF gene. The fourth exon codes for 140 amino acids of the TNF matured protein which is composed of 157 amino acids. A major portion of the fourth exon was isolated and then ligated to a synthesized DNA fragment coding for the remaining amino acids. The partial synthetic hTNF (rhTNF) cDNA thus generated was subcloned into a vector and successfully expressed in E. coli. 5-1 fermentator was used to produce rhTNF. About 20 g (wet weight) of bacterial pellet per liter medium and 10(6)-10(7) units of cytotoxicity to L929 cells per milliliter medium were obtained. rhTNF was purified by HPLC and dried with a freeze dryer. rhTNF with a purity of about 95% in the form of white powder was obtained. The sequence of ten amino acids at the amino terminus of the rhTNF was determined. The result showed that it was identical with that of the natural human TNF.

Base Sequence↗
PubMed1991

High level desmin expression depends on a muscle-specific enhancer.

Expression of the desmin gene is increased several-fold during myogenesis. To identify the DNA sequences involved in this regulation, a 16-kilobase fragment containing a 4.5-kilobase 5'-flanking region and the complete sequence of the human desmin gene has been isolated. The transcription initiation sites were determined by S1 nuclease mapping and primer extension analysis. A series of constructs have been made by fusing different lengths of human desmin 5'-flanking fragments to the bacterial chloramphenicol acetyl transferase (CAT) gene, these constructs were introduced either into mouse myogenic cells or into nonmyogenic cells. Comparison of the transient expression of CAT between myogenic and nonmyogenic cells demonstrated that the sequence including 228 base pairs upstream of the transcription initiation site is sufficient to confer low level, muscle-specific expression of the desmin gene. A negative region was located between -693 and -228 base pairs relative to the desmin mRNA start site. High level expression of the gene depends on a 280-base pair muscle-specific enhancer located between -693 and -973 base pairs upstream of the transcription initiation site. This enhancer can activate either the desmin promoter or heterologous promoters about 20-70-fold in myogenic cells. The enhancer, which also acts in myoblast, is discussed in the context of early expression of the desmin during skeletal myogenesis in the mammalian embryo.

Animals↗