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Biomedical subjects

M He

Publications and source records attributed to M He.

At least 163 records · Page 9Linked to original sources
PubMed1993

Differential polymerase chain reaction in the analysis of gene dosage.

Abnormalities of gene dosage are important in human disease. We have developed the differential polymerase chain reaction (PCR) to detect gene amplification and deletion in small amounts of tissues whose DNA may be degraded. The current utility of differential PCR required optimization of DNA isolation procedures, of primer selection approaches, and of PCR conditions. From this experience, we have formulated a theoretical framework for the technique, and describe appropriate applications and potential improvements based on emerging PCR technologies. Special emphasis is placed on the analysis of formalin fixed and paraffin embedded, archived specimens.

Base Sequence↗
PubMed1993

Genetic alterations in the p53 gene in the blast crisis of chronic myelogenous leukemia: analysis by polymerase chain reaction based techniques.

Rearrangements of the c-abl protooncogene and the bcr-gene are found in > 90% of patients in chronic phase of chronic myelogenous leukemia (CML). The molecular events leading to blast crisis, however, have not been well characterized. Gross alterations of the p53 gene have been detected in 30% of patients with blast crisis. Since point mutations in the p53 gene appear to be important in the process of transformation in many epithelial tumors, we looked for these mutations in the critical regions of the p53 gene (exons 4, 5, 6, 7, and 8). We used the polymerase chain reaction (PCR), direct sequencing, differential PCR, and single strand conformation polymorphism (SSCP) analysis to detect mutations of the p53 gene in samples from 21 patients with CML blast crisis. Two of 21 patients exhibited an intragenic deletion or rearrangement in p53. In addition, these patients were homozygous for the mutant p53 allele. No mutations were found in the p53 gene of the remaining 19 patients. However, sequencing of the CML blast crisis cell line, K562, revealed an insertion of a C at base position 956 within the fifth exon, causing a frame shift mutation and an early translational stop at codon 148. We conclude that, in contrast to solid tumors, mutations in exons 4-8 of p53 are not frequently seen in primary samples from CML blast crisis. However, deletions and/or rearrangements within the p53 gene do occur and may contribute to the progression from chronic phase to blast crisis in a limited number of patients with CML.

Base Sequence↗
PubMed1992

Optimized centrifugation for rapid elution of DNA from agarose gels.

A simple method has been developed for the isolation of DNA from agarose gels. Centrifugation in a low-cost device for 45 s at low speed provides a high yield of DNA suitable for further manipulation by restriction enzymes, T4 DNA ligase, Taq polymerase, Klenow fragment, and T4 polynucleotide kinase, and also for sequencing. In contrast, centrifugation for greater than 1 min leads to coelution of substances that inhibit DNA ligase.

Blotting, Southern↗
PubMed1992

A pink bacterium as a reporter system signaling expression of a recombinant protein.

We describe a set of expression vectors, pEX-PINK/0-3, for high-level production of (un)fused target proteins. The vectors incorporate a 'pink' reporter element, which signals in vivo the expression status of a target gene. A target sequence is cloned between the lambda PL promoter and the downstream mammalian cytochrome b5 gene. Thermo-induction drives transcription of a dicistronic mRNA from which the target protein and cytochrome b5 are independently and concurrently synthesized. Positive expression is indicated by visual transformation of bacteria from a grey/translucent to a bright pink color derived from tandemly expressed holocytochrome b5. The signal can be monitored in vivo spectrophotometrically.

Base Sequence↗
PubMed1992

A muscle-specific actin gene from the Mediterranean fruit fly, Ceratitis capitata.

A characterization of an actin gene isolated from the genome of the Mediterranean fruit fly, Ceratitis capitata, including the complete sequencing of the coding, 3' and 5' flanking regions of this gene and a partial cDNA was carried out. The partial cDNA was derived from the 3' untranslated region of the actin gene described here, and has been used to identify this gene uniquely. The DNA sequence data presented here, together with the pattern of expression exhibited by this gene during development, strongly support the interpretation that this is a muscle-specific actin gene. Peaks of expression are seen in tissues and during temporal phases of development where muscle differentiation is occurring. The derived protein sequence of the Medfly acting gene shows the highest degrees of similarity, 98.4 and 96.6% respectively, with the two muscle-specific actin genes 79B and 88F from D. melanogaster. The Medfly actin gene also has a single intervening sequence, and an intron is found at the same position in the 79B and 88F actin genes. In the coding region at the DNA level, 17.2 and 16.4% nucleotide differences, respectively, are observed between the Medfly actin gene and these same two D. melanogaster actin genes. The disparity between the amino acid and nucleotide comparisons can be explained, in part, by a high level of synonymous changes in the DNA sequence. In addition, despite the many similarities, codon usage appears to be very different between the actin genes of these species.

Actins↗
PubMed1992

[Experimental studies on growing seedlings of Morinda officinalis How].

By using the techniques of growing seedlings in bowshaped shed covered with plastic sheeting plus treatment with plant growth regulator, vegetative and generative propagation tests have been made of Morinda officinalis. Scientific evidences have thus been provided for growing seedlings of Morinda officinalis.

Indoleacetic Acids↗
PubMed1992

Analysis of gene amplification in archival tissue by differential polymerase chain reaction.

Oncogene amplification is found in many human tumors, and its detection may have important prognostic value. However, analysis of gene amplification may be hampered by inadequate tissue or poor DNA quality. We have previously described a polymerase chain reaction (PCR)-based procedure called differential PCR that can detect variations in gene dosage using miniscule amounts of tumor DNA [Frye, R.A., Benz, C.C. & Liu, E. (1989). Oncogene, 4, 1153-1157]. We now report the optimization of this technique for the analysis of oncogene amplification in paraffin-embedded archival tissues. We find that differential PCR is able to detect amplification of the HER2 (c-erbB-2) and the epidermal growth factor receptor (EGFR) genes and can be used to arrive at a semiquantitative estimate of gene dosage. Furthermore, our approach can determine gene amplification in samples in which the DNA is significantly degraded. Using differential PCR on paraffin-embedded tissues from cases previously investigated by standard DNA extraction and dot-blot procedures, good correlation between the two methods was found. Approaches are described to overcome technical problems posed by factors that affect the differential PCR, including the method of DNA extraction and extreme fragmentation of the DNA (less than 200 base pairs). Furthermore, the resulting analytical algorithm reported herein has proved effective in detecting oncogene amplification in archival breast cancer specimens from standard pathology laboratories. Thus, differential PCR will be particularly helpful in the analysis of tumor specimens that are archived, small in size or rare in occurrence.

Algorithms↗
PubMed1992

The HER2 (c-erbB-2) oncogene is frequently amplified in in situ carcinomas of the breast.

Amplification and overexpression of the HER2 (c-erbB-2) oncogene was assessed in paraffin-embedded specimens from 27 in situ carcinomas of the breast and from 122 stage II breast cancers. Gene amplification detected in these archival tissues by differential polymerase chain reaction (PCR) was found in 48% of in situ carcinomas and in 21% of stage II lesions (chi 2 = 7.62, p less than or equal to 0.01). In addition, the level of gene amplification correlated with the level of HER2 oncoprotein expression as measured by immunohistochemistry for both in situ cancers (p less than or equal to 0.025) and stage II cancers (p less than or equal to 0.0005). This high incidence of HER2 gene amplification with accompanying overexpression in non-invasive breast tumors suggests that perturbations of the HER2 oncogene are among the earliest and most common genetic lesions in human breast cancer.

Breast Neoplasms↗
PubMed1991

An improved and rapid procedure for isolating RNA-free Escherichia coli plasmid DNA.

We describe a simple, rapid, and inexpensive procedure for the isolation of plasmid DNA in high yields from Escherichia coli cultures. The procedure entails two main steps, which involve treating intact bacterial cells with phenol/chloroform in the presence of Triton X-100 and LiCl followed by polyethylene glycol precipitation. Plasmid DNA preparations isolated by this method are highly pure and virtually devoid of RNA. The DNA is suitable substrate for restriction mapping, DNA-modifying enzymes, and in vitro transcription with SP6 and T7 RNA polymerases.

Chemical Precipitation↗
PubMed1991

[Study on relationship between human ABO blood groups and type A behavior pattern].

Investigation of the relationship between ABO blood groups (ABO BG) and Type A behavior pattern (TABP) was performed. No significant correlation was found between human ABO BG and TABP (P less than 0.05). However, CH and TH + CH scores in individuals with blood type A and type A personality were significantly lower (P less than 0.05). The values of TH-CH scores among tested people were of no statistical significance (P greater than 0.05). Moreover, nearly half of the examinees (41.32%) had higher CH score and the distribution of the individuals was obviously different in statistics (P less than 0.005). In addition, L score of examinees with blood type A and type B personality was relatively lower.

ABO Blood-Group System↗
PubMed1991

[A prospective controlled study of psychosomatic and immunologic change in recently bereaved people].

This research was carried out in 45 bereaved people who were the close relatives of a bus accident victims. Their mental and physical conditions, IgA, IgG, IgM, C3 and C4 levels were measured. It reveals that mental and physical conditions of the investigated group declined and the incidence of infectious diseases increased in comparison with the control group. Subjects antibody and complement functions were inhibited after bereavement. The social support they perceived functions in the way of buffering the stress as well as improving the immunity.

Adolescent↗
PubMed1990

[The treatment of lower leg fractures with Meng He's external fixator].

Within the antagonism existing between the functional intention of treatment methods of the traditional Chinese medicine and the anatomic view of "occidental" medicine, an external fixation device has been developed which is most likely to become the method of choice in fractures of the leg and other bones under the medical conditions of China.

Accidents, Occupational↗
PubMed1990

Actin genes in the Mediterranean fruit fly, Ceratitis capitata.

We have undertaken the study of actin gene organization and expression in the genome of the Mediterranean fruit fly (medfly), Ceratitis capitata. Actin genes have been extensively characterized previously in a wide range of eukaryotic organisms, and they have valuable properties for comparative studies. These genes are typically highly conserved in coding regions, represented in multiple copies per genome and regulated in expression during development. We have isolated a gene in the medfly using the cloned Drosophila melanogaster 5C actin gene as a probe. This medfly gene detects abundant messages present during late larval and late pupal development as well as in thoracic and leg tissue preparations from newly emerged adults. This pattern of expression is consistent with what has been seen for actin genes in other organisms. Using either the D. melanogaster 5C actin gene or the medfly gene as a probe identifies five common cross reacting EcoRI fragments in genomic DNA, but only under less than fully stringent hybridization conditions.

Actins↗