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Biomedical subjects

Y Pan

Publications and source records attributed to Y Pan.

At least 199 records · Page 11Linked to original sources
PubMed1995

Anti-idiotypic antibodies: biological function and structural studies.

Under a variety of circumstances antibodies can be elicited against the variable region of other antibody molecules (anti-idotypic antibodies, anti-ids). Some of the antibodies are directed against the binding sites of the eliciting antibodies. Of particular interest are the antibodies that recognize epitopes of the original antibody that are in contact with antigen. Antibodies of this kind have been produced and used in a variety of situations including attempts at using them as therapeutic agents. In recent years structural data at the atomic level have emerged for anti-idiotypic antibodies from X-ray diffraction studies. These studies provided structural basis for molecular mimicry of anti-ids. For a large globular antigen (lysozyme), where epitope is noncontinuguous, molecular mimicry is not present at the atomic level. In this case, idiotopes are largely composed of CDR residues, but framework residues are also used. For an epitope that is sequence-specific (anti-FIPV system), molecular mimicry appears to be present as evidenced by the sequence homology between the CDR loops of the anti-id and the epitope of the original antigen. In the case of a small hormone antigen (angiotensin II), an internal image of the eliciting antigen appears to be represented in a single CDR loop of the antiiodiotypic antibody.

Amino Acid Sequence↗
PubMed1995

Transcription patterns of sequences on human chromosome 21.

The polymerase chain reaction (PCR) was used to screen embryonic, fetal and adult human cDNA libraries for transcription on chromosome 21q22.1-->q22.3. Seventy-three pairs of oligonucleotide primers on chromosome 21, used previously to screen a fetal brain cDNA library, were applied to analyze 41 different cDNA libraries. Only phage eluate (and therefore no DNA isolation) was required for this sensitive screening. Sixty primer pairs were positive with at least one cDNA library, indicating that the majority of primers were derived from transcribed sequences. Even with our most complex human fetal brain cDNA library, we detected only 57% (34/60) of transcribed sequences, illustrating the need to screen multiple human cDNA libraries to determine if transcription occurred. Since only 3/73 clones were present in only one cDNA library, the vast majority of transcribed sequences are present in more than one tissue.

Chromosomes, Human, Pair 21↗
PubMed1995

Quantitative analysis of repeat adenovirus-mediated gene transfer into injured canine femoral arteries.

We quantitatively evaluated the effectiveness of a repeat administration of a recombinant adenoviral vector expressing bacterial Escherichia coli lacZ into the same arterial site of a relatively large animal, the dog. The replication-defective adenoviral vector was introduced percutaneously into balloon-injured femoral arteries through a double-balloon catheter. After a single dose of adenoviral vector, up to 90% of surface (73 +/- 16%, n = 7) and smooth muscle cells in multiple layers of the media showed transgene expression as evaluated by 5-bromo-4-chloro-3-indoyl beta-D-galactopyranoside histostaining without extralocal expression, as assessed by polymerase chain reaction. High-level expression (measured as beta-galactosidase activity) peaked 7 days after transfer and was transient, although it was retained for a month. Second does of the same adenovirus to the same arterial site were given 1, 2, 5, or 8 weeks after the first administration. At 1 week the second dose significantly enhanced lacZ expression. At 2, 5, or 8 weeks the second dose reinduced lacZ expression at 25% to 30% of the full expression. lacZ expression was also detected in preimmuned dogs, although the expression levels correlated inversely to the titer of neutralizing antibodies in their serum. These results demonstrate that arterial gene expression can be enhanced by a second administration of the same adenovirus after a short interval and that a repeat dose after a long interval partially but significantly reinduces gene expression despite the presence of an immune response. These data may provide an additional scientific foundation for the use of adenovirus-mediated arterial gene transfer in future clinical practice.

Adenoviridae↗
PubMed1995

[Influence of fluoride varnish of different concentration on microhardness of enamel surface]

Varnish is a new type oral material which develops rapidly in recently years,It have had extensive study abroad.It is one of the topical application of fluoride,among them,fluoride-sodium varnish have more significant effect on prevention of dental caries.This study observed the changes of microhardness of cramels after applying fluorid-sodium varnish of different concentration to enamel surfaces.Enamels were randomly parted into three groups,A.B and C.Before fluoride application,the microhardness of enamels were detected,and no significant difference were found among three groups,After that,0.5%,1.5%,2.7% fluoride-sodium varnish were daubed respectively on the three groups enamel surfaces for 24h.The microhardness of enamels were detected again.The results showed all the microhardness of enamels have significant increase statistically after applying fluoride-sodium varnish of different concentration.But,for 0.5% fluorid-Sodium varnish,the increase of microhardness of enamels was only one half of the other two group,which suggested in some concentration range,the fluoride concentration increased one time,the microhardness of enamels increased about one time, but the increase of microhardness of enamels was not synchronized with the increase of fluoride concentration.The increase of microhardness of enamels is almost the same between the two high concentration fluoride-sodium varnish groups,and there in no significant difference statistically.That is when some fluoride concentration were reached,the microhardness of enamels won't increase any more.By the experiment,the writer suggests 1.5% fluorid-sodium varnish is the best on prevention of dental caries.

Journal Article↗
PubMed1995

[The change of platelet number in patient with acute myocardial infarction and its clinical significance].

Platelet number and alpha-granule membrane protein (GMP-140) level on platelet surface were determined in 20 patients with acute myocardial infarction (AMI) and 20 normal subjects. The results showed that platelet number decreased significantly after AMI, especially on the second day after onset and that the level of GMP-140 increased rapidly after AMI and reached a peak on the second after the attack. Both returned to the normal on the 5-7th day after the heart attack. Correlative analysis between increase of serum CK-MB and platelet number was negative (r = -0.6123, P < 0.005), and positive between that and GMP-140 level (r = 0.5895, P < 0.01). Platelet number decreased markedly in cases with heart failure and cardiac death. The results indicate that platelets are involved in the pathological process of AMI.

Adult↗
PubMed1995

Percutaneous transluminal gene transfer into canine myocardium in vivo by replication-defective adenovirus.

OBJECTIVE: The aim was to examine the feasibility, efficiency and safety of adenovirus-mediated in vivo gene transfer into the canine myocardium by a percutaneous transluminal method using a needle-catheter. METHODS: Either a replication-defective adenovirus (Adex1SRLacZL) or a plasmid (pSRLacZ), both expressing E. coli lacZ coding beta-galactosidase (beta-gal), was directly injected into the left ventricle of dogs through a needle-catheter inserted via a femoral artery. Expression of lacZ was examined by histochemical staining and quantified by measuring beta-gal activity. RESULTS: Injections with Adex1SRLacZL induced lacZ expression as a result of 40 out of 41 injections; the expression level was 10 times higher than that obtained with pSRLacZ. Induced beta-gal activity was detected within 24 h, peaked at 7 days and retained for 2 weeks after gene transfer. A repetitive administration of the same adenovirus at 14 days after the first injection also evoked a reduced but significant level of expression despite neutralizing antibodies to adenovirus in serum. Although injection induced an inflammatory response that peaked at 3 days after injection and gradually subsided without a second peak, the temporal change and the extent of inflammation induced by adenovirus injection was not significantly different from those induced by injection with either saline or plasmid. Neither leakage of enzymes such as CPK or LDH nor alteration in the ECG was detected in the 30 days following gene transfer. CONCLUSIONS: Our findings demonstrate that a catheter-mediated direct injection with an adenovirus can induce gene expression in the ventricle more efficiently without additional myocardial damage and inflammation compared with injection with a plasmid. A repeat dose of the same adenovirus elicited gene expression at an attenuated but significant level. This method may potentially have clinical applications: in modifying myocardial phenotype and/or improving general circulation under certain circumstances.

Adenoviridae↗
PubMed1995

[Analysis of 29 maternal deaths caused by amniotic fluid embolism].

Twenty nine maternal deaths caused by amniotic fluid embolism (AFE) during 1989-1993 in Beijing area were reviewed. The results show that the average maternal mortality ratio due to AFE was 5.9/100,000 live births responsible for 15.5% of total maternal deaths. In 13 of the 29 patients presented the clinical signs were of postpartum hemorrhage and coagulation disorders. Oxytocics had been used in 12 of the 29 cases during labor. In more than half of the patients there was delay in diagnosis. This was that the percentage of AFE which may present with the signs of coagulation disorder was higher than previously thought, and unreasonable use of oxytocics during labor may be associated with AFE. This kind of AFE is easy to misdiagnose.

Adult↗
PubMed1995

[Study on animal conservation-selection index].

The concept of "conservation-selection index" was put forward based on the idea of Systematic Conservation that the conservation and selection must be combined in practice. Its calculation formula was also derived, which suits to various data and various aims of conservation and selection.

Animals↗
PubMed1995

[A study on behavioural characteristics of staying on the mountain and its relationship with malaria infection in Li and Miao minorities in Hainan Province].

A study of sociology combined with epidemiology was conducted in Li Minority's two villages and Miao Minority's two villages nearby the foot of mountain in a historically malaria hyperendemic area, Nanqiao Township of Wanning County in August, 1993. The results showed that malaria infection was closely correlated to the behaviour of staying overnight on the mountain of Li and Miao Minorities during farming seasons. Most of Li people stayed overnight on the mountain for planting areca were adults, accounting for 21.6% of the whole population, the duration of stay was about half a year; Miao people stayed overnight on the mountain planting and harvesting upland rice, always with their family member, so the percentage of people who had stayed on the mountain was as high as 82.1%, the duration of stay was about one and half a month. Blood smear examination showed that the malaria parasite rates in both Li and Miao villages were 11.1% and 24.1%, respectively, the positive rate of P. falciparum was 1.0% and 9.1%, respectively, the positive rate of IFA (titer >or= 1 : 40) was 31.2% and 46.5%, respectively. It is indicated that both the rate of parasitaemia and the P. falciparum infection were much higher in Miao Minority than those in Li Minority (P < 0.001). A cohort analysis showed that the malaria parasite rate of population who having not stayed, having ever stayed and being stayed on the mountain was 6.5%, 27.4% and 42.1%, respectively, of them the rate of P. falciparum infection was 0.5%, 8.8% and 18.4%, respectively. The results suggest that malaria acquired from mountainous forest referring to "up-mountain infection" is a major source of malaria infection and a significant risk factor in determining the prevalence of malaria (especially falciparum malaria) in Hainan Province. This behavioural risk factor has become the main obstacle for malaria control in Hainan Province. Therefore, controlling "up-mountain infection" and adopting appropriate anti-malaria measures to protect the risk population who have to work and stay on the mountain should be strengthened in the malaria control program.

China↗
PubMed1994

The effect of eight V2 vasopressin receptor mutations on stimulation of adenylyl cyclase and binding to vasopressin.

We previously identified six V2 vasopressin receptor mutations in five unrelated nephrogenic diabetes insipidus (NDI) families. In order to elucidate the effect of these mutations on the function of the V2 vasopressin receptor, we introduced these six and two additional, naturally occurring mutations into the V2 vasopressin receptor gene by in vitro mutagenesis. Five of the mutants (two frameshift, one nonsense, and two missense) failed to stimulate adenylyl cyclase due to their inability to bind vasopressin under the experimental conditions. In contrast, ligand binding and cAMP accumulation were normal for two other mutations, a A61V missense mutation and an in-frame deletion of four amino acids (Arg-247 to Gly-250), suggesting that they are not the cause of NDI in these families. The deletion mutation was found in a family in conjunction with a second mutation, R181C, which yielded a much reduced ligand-binding capacity. The KD of R181C was at least 26 times higher than that of the wild type. Further characterization by an immunofluorescent assay showed that the R181C mutant receptor is expressed and distributed on the cell surface in a manner similar to that of the wild type. This finding indicates that the inability of this mutant to stimulate adenylyl cyclase is caused by the reduced capacity for vasopressin binding and that the R181C mutation is responsible for NDI in this family.

Adenylyl Cyclases↗
PubMed1994

p53 deletion as a genetic marker in urothelial tumor by fluorescence in situ hybridization.

In order to investigate the significance of p53 deletion, 42 specimens of transitional cell carcinoma were analyzed by interphase cytogenetics with a fluorescence in situ hybridization technique and compared with clinicopathological and cytochemical parameters. In total, 27 (64%) and 16 (38%) specimens demonstrated p53 deletion and overexpression, respectively. The p53 deletion was significantly correlated with grade (P < 0.01), stage (P < 0.05), S-phase fraction (P < 0.05), and DNA ploidy (P < 0.01), while p53 overexpression correlated only with grade (P < 0.05). The close correlation of p53 deletion with clinicopathological parameters suggests p53 deletion to be of clinical importance to indicate the malignant potential of human urothelial tumors.

Adult↗
PubMed1994

Nonrandom numerical aberrations of chromosomes 7, 9, and 10 in DNA-diploid bladder cancer.

Double-target in situ hybridization technique (ISH) was applied to 37 cases of bladder cancer to detect numerical aberrations of chromosomes 7, 9, 10, and 11 by centromeric DNA probes. Of 33 evaluable cases, 29 (88%) demonstrated chromosome aberrations. In 17 cases with diploid pattern as measured by flow-cytometric DNA analysis (FCM), 15 (88%) demonstrated chromosome aberrations. Of these, trisomy 7, monosomy 9, and trisomy 10 were detected in three, three, and one case, respectively, as a single chromosome aberration. In 14 (88%) of 16 cases with an aneuploid DNA pattern, chromosome aberrations for two or more chromosomes were demonstrated. A significant correlation was observed between grade of chromosome aberrations and tumor grade (p < 0.01, Fisher's test), between number of spots for chromosome 7 and peak value in FCM (p = 0.015, by Spearman rank order test). In eight cases, chromosome aberrations in the tumor were compared with the corresponding pattern in the grossly normal and histologically benign mucosa. Trisomy 10 and monosomy 9 were detected as chromosome numerical aberrations in the histologically normal mucosa, consistent with aberrations in the corresponding patients. We conclude that trisomy 7, monosomy 9, and trisomy 10 may be early events in the evolution of bladder cancer.

Carcinoma, Transitional Cell↗
PubMed1994

Blood-brain barrier disruption in experimental focal ischemia: comparison between in vivo MRI and immunocytochemistry.

The definition of blood-brain barrier (BBB) damage in cerebral ischemia using contrast-enhanced MRI has not been clearly correlated to the spread of edema or other histological measures of barrier disruption. In this study, we used a rabbit model of focal cerebral ischemia to compare GdDTPA-enhanced MRI with spin-echo images of brain injury and immunocytochemical detection of BBB damage and vasogenic edema. After 4 h of transient ischemia followed by 6 h of reperfusion, in vivo T2W and T1W images were obtained in a 1.5 T magnet using a 3-inch surface coil. After MRI, the animals were sacrificed and anti-serum protein (IgG) monoclonal antibodies were used to detect regions of increased BBB permeability to serum proteins. Ischemic neuronal damage was confirmed with cresyl-violet histology. T2W scans showed focal regions of increased signal intensity in the ischemic hemisphere (17.0 +/- 4.1%) that primarily involved the cortex and striatum. T1W scans showed corresponding regions of hypointensity but demonstrated, in general, smaller lesion sizes (10.1 +/- 2.9%). GdDTPA-enhanced images showed variable areas of BBB disruption that included regions of intense leakage as well as lesions that only showed subtle enhancement along the periphery of damaged tissue. It appeared that large and more severe lesions corresponded to peripheral enhancement whereas smaller lesions showed central parenchymal enhancement. The extent of MR contrast enhancement did not correlate well with immunocytochemical images of serum protein leakage. Anti-IgG stains demonstrated widespread regions of BBB damage corresponding with areas of damaged neurons that appeared pyknotic on cresyl-violet sections.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The effects of naloxone on the post-asphyxic cerebral pathophysiology of newborn lambs.

Both early post-ischaemic blood-brain barrier disruption and enhanced brain endogenous opioid system activity have been implicated in the pathogeneses of ischaemic neuronal damage; however, their roles in neonatal asphyxia have not been evaluated. Under alpha-Chloralose anaesthesia, 17 newborn lambs were asphyxiated until their mean arterial pressures were < or = 25 mmHg. They were then immediately resuscitated, and assigned to two groups. Group I, but not group II lambs received IV bolus of 10 mg kg-1 Naloxone within 5 min of resuscitation. The infusion was continued at the same dose hourly until sacrificed 24 h post-asphyxia. Arterial pH/gases, intracranial/arterial pressures, and rectal temperature were monitored. Neurological examinations were performed on both groups prior to sacrifice, and the blood-brain barrier integrity was assessed by Evans blue. Despite aggressive resuscitation, 5 lambs died during asphyxia, but 12 survived and were assigned according to the protocol. There were no significant group differences in the magnitude of asphyxia, arterial and intracranial pressures. However, blood-brain barrier disruption was observed in 5 out of 6 untreated, and in only 1 of the 6 lambs treated with Naloxone (p < 0.05). Severe neurological abnormalities were observed in 75% of lambs with disrupted, but in none of the animals with intact blood-brain barrier (p < 0.05). Our study suggests that post-asphyxia blood-brain barrier disruption is causally related to poor neurological outcome, and that Naloxone prevents both the disruption, and the neurological dysfunction among those survivors with intact blood-brain barrier.

Animals↗
PubMed1994

Destructive processes of salivary gland parenchyma and development of epimyoepithelial islands assessed by immunohistochemistry.

Thirteen salivary gland lesions showing destructive features and development of epimyoepithelial islands were studied using a panel of monoclonal antibodies to B cell (Dako, CD20 L26), T cell (UCHL1), macrophage histiocyte MH cell (Dako, MAC387), cytokeratin PKK1, KL1, K8.12, actin, vimentin and Von Willebrand factor (v WF). B cells were distributed closely in some limited areas and T cells were scattered throughout the lesion. MH cells were located particularly in the periductal tissue as well as in ducts and acini. Actin staining was positive in myoepithelium around acini but was negative or weak around degenerative acini. Endothelial cells of blood vessels stained strongly with v WF. Cytokeratin KL1 and K8.12 were positive in duct cells of the unaffected area while in the degenerative region they were negative or weak. K8.12 was positive in epimyoepithelial islands, indicating that the epimyoepithelial cells in lymphoepithelial lesions may originate from duct basal cells.

Adult↗