Biomedical subjects

L Jin

Publications and source records attributed to L Jin.

At least 433 records · Page 24Linked to original sources

PubMed1991

Analysis of pituitary hormones and chromogranin A mRNAs in null cell adenomas, oncocytomas, and gonadotroph adenomas by in situ hybridization.

To study the relationship between null cell adenomas, oncocytomas and gonadotroph adenomas, we analyzed 32 surgically removed formalin-fixed paraffin-embedded pituitary tumors for the expression of pituitary hormone messenger RNAs (mRNAs) by in situ hybridization (ISH). Most tumors were also analyzed for chromogranin A mRNA. To identify the cell type constituting the tumors and to assess hormone content, all tumors were investigated by histology, transmission electron microscopy and immunohistochemistry. Most null cell adenomas (6/11) and gonadotroph adenomas (9/10) expressed the mRNAs for alpha-subunit of glycoprotein hormones whereas only 2/11 oncocytomas expressed alpha-subunit mRNA. FSH beta and/or LH beta mRNA were present in most null cell and gonadotroph adenomas but only in a few oncocytomas. Prolactin (PRL) mRNA was detected in two null cell tumors and in one gonadotroph adenoma, whereas GH and POMC mRNA were present in one null cell adenoma. Chromogranin A mRNA, which codes for the major secretory granule protein, was present in 25/26 tumors including all tumors that were negative for pituitary hormone mRNAs, indicating adequate preservation of specific mRNA transcripts in the paraffin-embedded sections of tumor cells. These results indicate that null cell adenomas and gonadotroph adenomas are closely related neoplasms and that oncocytomas may represent a functionally defective form of null cell adenoma characterized by mitochondrial abundance, which has retained the capacity to synthesize the major secretory granule protein chromogranin A. Although the cytogenesis of null cell adenomas and oncocytomas is not clear, it can be suggested that these two tumor types are derived from a pluripotential precursor cell that is capable of undergoing multidirectional differentiation and synthesizing various hormones, mainly glycoproteins.

Adenoma↗

PubMed1991

[Dynamic changes in fibrinolytic system in patients with acute myocardial infarction].

Dynamic change of serum tissue-type plasminogen, activator (t-PA) and PAI activity was studied in 22 cases with acute myocardial infarction (AMI) 11 cases with unstable angina (UA) and 24 healthy persons. The group of AMI was divided into two subgroups, one with severe complications, AMI-A subgroup and the other without complication, AMI-B subgroup. The results revealed: t-PA activity was decreased in AMI group, especially in AMI-A subgroup; PAI activity was markedly increased in AMI-A subgroup in first three days after onset; there was a marked decrease of active type in AMI-A subgroup. The study confirms that the function of fibrinolytic system is abnormal in patients with AMI and UA. The change of activity of t-PA and PAI is closely related with the severity of AMI. It is important to augment the activity of the fibrinolytic system in the treatment of AMI.

Adult↗

PubMed1991

Subcloning and expression of midecamycin polyketide synthase genes from Streptomyces mycarofaciens 1748.

A 2.4 kb fragment containing the midecamycin polyketide synthase genes (mps) was subcloned from the preliminary clone pCN8B12 out of the genomic library of midecamycin-producing strain S. mycarofaciens 1748, by using the homologous DNA of the actinorhodin polyketide synthase gene (act I) as hybridization probe. This DNA fragment was subcloned onto Streptomyces/E. coli shuttle vector pMHM3. A recombinant plasmid pCG2 was obtained. The transformation of the polyketide synthase deficient mutant of actinorhodin-producing strain, S. colicolor TK17, with pCG2 DNA resulted in the production of an antibacterial compound which was similar neither to actinorhodin nor to midecamycin. The transformation of spiramycin-producing strain S. ambofaciens with pCG2 DNA increased spiramycin production in the fermentation broth. The transformation of the regulatory mutant of daunorubicin-producing strain with pCG2 DNA resulted in the production of epsilon-rhodomycinone verified by TLC and HPLC analyses. The pCG2 DNA also could be functionally expressed in tetracenomycin C-producing strain S. glaucescens. However, it could not be expressed in the blocked mutants of erythromycin-producing strain Saccharopolyspora erythrarea WMH 15,261. These suggest that the pCG2 DNA may complement polyketide synthase gene deficiency or have some regulatory function in certain polyketide antibiotic-producing strains.

Cloning, Molecular↗

PubMed1991

Expression of neural cell adhesion molecule in normal and neoplastic human neuroendocrine tissues.

The neural cell adhesion molecule (N-CAM) is a group of cell surface glycoproteins involved in direct cell--cell adhesion. N-CAM expression in normal and neoplastic tissues was examined with specific antibodies and oligonucleotide probes by immunohistochemistry and in situ hybridization. Most neuroendocrine cells and tumors with secretory granules expressed N-CAM protein and mRNA. Parathyroid adenomas (4) were somewhat unusual, because N-CAM mRNA, but not protein, was detected in some of these benign neoplasms. Most non-neuroendocrine cells and tumors did not express N-CAM, although uterine smooth muscle and an adrenal cortical carcinoma were both positive. Western blots disclosed proteins of 180, 140, and 120 kd in normal adult brain, whereas two pheochromocytomas, a null cell adenoma, and a gastrinoma had proteins of approximately 180 and 140 kd. These results indicate that N-CAM protein and mRNA are widely expressed in neuroendocrine cells and neoplasms. N-CAM oligonucleotide probes as well as antibodies against N-CAM can be used as broad-spectrum neuroendocrine markers. In addition, these molecular probes can be used to examine the role of N-CAM in the development and regulation of neuroendocrine tissues.

Cell Adhesion Molecules, Neuronal↗

PubMed1990

Immunochemical localization of heparanase in mouse and human melanomas.

Heparanase, an endo-beta-D-glucuronidase, has been associated with melanoma metastasis. Polyclonal antibodies directed against the murine N-terminal heparanase peptide detected a Mr approximately 97,000 protein on SDS-PAGE of mouse melanoma and human melanoma cell lysates. In an indirect immunocytochemical study, human A375-SM and mouse B 16-BL6 melanoma cells were stained with the anti-heparanase antibodies. Heparanase antigen was localized in the cytoplasm of permeabilized melanoma cells as well as at the cell surface of unpermeabilized cells. Immunohistochemical staining of frozen sections from syngeneic mouse lungs containing micrometastases of B16-BL6 melanoma demonstrated heparanase localized in metastatic melanoma cells. Similar studies using frozen sections of malignant melanomas resected from patients indicated that heparanase is localized in invading melanoma cells. Our studies suggest that (a) the N-terminus of the heparanase molecule in mouse and human is antigenically related; (b) heparanase antigens are localized at the cell surface and in the cytoplasm of metastatic human and mouse melanoma cells; and (c) heparanase antigens are enriched in invasive and metastatic murine and human melanomas in vivo.

Animals↗

PubMed1990

Limitations of the evolutionary parsimony method of phylogenetic analysis.

Lake's evolutionary parsimony (EP) method of constructing a phylogenetic tree is primarily applied to four DNA sequences. In this method, three quantities--X, Y, and Z--that correspond to three possible unrooted trees are computed, and an invariance property of these quantities is used for choosing the best tree. However, Lake's method depends on a number of unrealistic assumptions. We therefore examined the theoretical basis of his method and reached the following conclusions: (1) When the rates of two transversional changes from a nucleotide are unequal, his invariance property breaks down. (2) Even if the rates of two transversional changes are equal, the invariance property requires some additional conditions. (3) When Kimura's two-parameter model of nucleotide substitution applies and the rate of nucleotide substitution varies greatly with branch, the EP method is generally better than the standard maximum-parsimony (MP) method in recovering the correct tree but is inferior to the neighbor-joining (NJ) and a few other distance matrix methods. (4) When the rate of nucleotide substitution is the same or nearly the same for all branches, the EP method is inferior to the MP method even if the proportion of transitional changes is high. (5) When Lake's assumptions fail, his chi2 test may identify an erroneous tree as the correct tree. This happens because the test is not for comparing different trees. (6) As long as a proper distance measure is used, the NJ method is better than the EP and MP methods whether there is a transition/transversion bias or whether there is variation in substitution rate among different nucleotide sites.

Base Sequence↗

PubMed1990

Detection of chromogranins A and B in endocrine tissues with radioactive and biotinylated oligonucleotide probes.

We analyzed the distribution of chromogranins A and B in normal and neoplastic endocrine tissues with secretory granules using 35S-labeled and biotin-labeled oligonucleotide probes by in situ hybridization (ISH). Both radioactive and nonradioactive probes detected messenger RNAs (mRNAs) in frozen and paraffin tissue sections. Endocrine tissues with variable immunoreactivities for chromogranin A protein, such as small-cell lung carcinomas, neuroblastomas, insulinomas, and parathyroid adenomas, expressed the mRNA for chromogranins A and B in most cells. Some technical problems with the biotinylated probes included nonspecific nuclear staining and endogenous alkaline phosphatase, which was not completely abolished by levamisole pretreatment. A differential distribution of chromogranins A and B was seen in pituitary prolactinomas, which expressed abundant chromogranin B but not chromogranin A mRNAs, and in parathyroid adenomas, which expressed abundant chromogranin A but only small amounts of chromogranin B mRNAs. These results indicate that ISH can be used to detect chromogranins A and B in endocrine tissues with radioactive and biotinylated oligonucleotide probes and that the mRNAs for chromogranin A and B are demonstrable in some tumors even when the chromogranin proteins cannot be detected by immunohistochemistry.

Biotin↗

PubMed1990

Gestational ethanol consumption on tissue amino acid levels: decreased free histidine and tryptophan in fetal tissues with concomitant increase in urinary histamine excretion.

The effects of ethanol consumption during pregnancy on maternal, placental, and fetal tissue amino acid levels and metabolism were investigated. Pregnant Sprague-Dawley rats were given 35% ethanol-calorie liquid diet, ad libitum, from gestation day 7 to 21. Control rats were pair-fed with isocaloric sucrose substituted for ethanol. Ethanol consumption decreased fetal body weight and increased placental weight. Twenty-four amino acids were determined in six tissues (maternal plasma and liver, placenta, fetal plasma, liver, and brain) by HPLC with orthophthalaldehyde derivatization. The effects of ethanol on free amino acid levels differed from tissue to tissue. In general, ethanol affected more amino acids in maternal plasma, fetal plasma, and liver. Maternal liver, placenta, and fetal brain amino acids were more resistant to ethanol effect. Two essential amino acids, histidine and tryptophan, were consistently decreased in fetal tissues by maternal ethanol consumption. The values (ethanol vs. control, nmole/ml or g, mean +/- SEM, N = 20) of fetal plasma, liver, and brain for histidine were 51.8 +/- 6.0 vs. 85.3 +/- 4.5 (p = 0.001), 269.0 +/- 26.4 vs. 503.7 +/- 47.3 (p = 0.0004), and 117.9 +/- 7.7 vs. 154.6 +/- 8.7 (p = 0.0055), respectively; and for tryptophan were 105.7 +/- 3.1 vs. 132.2 +/- 4.1 (p = 0.0001), 128.8 +/- 3.7 vs. 144.3 +/- 6.0 (p = 0.0407), and 83.4 +/- 7.2 vs. 103.6 +/- 3.2 (p = 0.0198), respectively. Histidine was also decreased in placenta by ethanol (138.1 +/- 6.6 vs. 189.1 +/- 11.8 nmole/g, p = 0.0014).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗

PubMed1990

Gonadotropin-releasing hormone regulates gonadotropin beta-subunit and chromogranin-B messenger ribonucleic acids in cultured chromogranin-A-positive pituitary adenomas.

Chromogranin-A-positive pituitary adenomas include glycoprotein hormone-producing adenomas, null cell adenomas, and a few other pituitary adenomas. We studied the effects of GnRH, CRF, dexamethasone, and phorbol 12-myristate 13-acetate on FSH and LH secretion and on FSH beta and chromogranin-A and -B mRNA expression in 10 chromogranin-A-positive adenomas in vitro to analyze the regulation of FSH and chromogranin-A and -B expression in these neoplasms. Most adenomas responded to GnRH stimulation during 7 days in culture with a 2- to 10-fold increase in FSH and LH secretion and a 2- to 7-fold increase in FSH beta mRNA compared to control values. CRF and phorbol 12-myristate 13-acetate also stimulated FSH and LH secretion 2- to 5-fold in five of seven and three of three cases, respectively, during 7 days in culture. Dexamethasone stimulated both FSH and LH secretion in two of three cases as well as FSH beta mRNA in vitro in the one case examined. GnRH treatment consistently produced a 2-fold increase in chromogranin-B mRNA, but not in chromogranin-A mRNA, after 7 days of culture. These results indicate that many chromogranin-A-positive adenomas respond to GnRH and CRF in vitro by increased hormone secretion and that GnRH stimulation leads to increased amounts of FSH beta and chromogranin-B mRNAs. The differential response of chromogranin-A and -B mRNAs after GnRH stimulation indicates that the chromogranin genes are highly regulated in these tumors.

Adenoma↗

PubMed1990

Penetration and stainability of modified Sato's lead staining solution.

The penetration and stainability of modified Sato's lead staining solution containing calcined lead citrate were studied. Modified Sato's lead solution was preserved for 1 week and for 2 years, each at room temperature and at 4 degrees C. Specimens were stained with these solutions to measure the stainability. After 2-min staining, specimens were stained to the depth of 1.0-1.2 microns even when there had been 2-year preservation of the staining solution. This modified solution could be preserved for a long time and good penetration and stainability could still be obtained. This solution is also suitable for the observation of semithin sections.

Animals↗

PubMed1990

[Detection of HBxAg in liver specimens of patients with hepatocellular carcinoma].

Detection of HBxAg was done by the immunogold-silver staining technique in 22 liver cancer specimens from patients with hepatocellular carcinoma and positive markers of hepatitis B were found to express HBxAg of hepatitis B virus, which was distributed in the perinuclear cytoplasm. The result suggests that HBxAg can be detected practically in all the liver specimens of the patients with hepatocellular carcinoma, who had been infected by hepatitis B virus. The relationship between X gene and its translation product and hepatocellular carcinoma is discussed.

Carcinoma, Hepatocellular↗

PubMed1990

Regulation of prolactin gene expression in a DMBA-estrogen-induced transplantable rat pituitary tumor.

A new transplantable rat pituitary tumor was induced in F344 female rats with dimethylbenz(a)anthracene and estrogen (MtT/F-DMBA) and studied for 20 serial transplant generations. The tumor grew without estrogen supplements in female rats by the second transplant generation. Sensitivity to estrogens, as indicated by a prolonged latency period for tumor development, was seen at the 20th, but not the 5th transplant generation. MtT/F-DMBA tumors expressed prolactin (PRL), growth hormone (GH), and adrenocorticotropin (ACTH) mRNAs. A decrease in the percentage of cells expressing PRL mRNA, PRL protein, and in the number of secretory granules per cell occurred with serial transplantation. S-100 protein-positive folliculostellate cells were present in the hyperplastic pituitary but not in the transplantable tumors. Estrogen treatment at the 20th transplant generation prolonged the tumor latency period, increased the number of cells expressing PRL mRNA greater than 5-fold by in situ hybridization analysis (14 +/- 2% versus 77 +/- 5%), increased PRL secretion (132 +/- 40 ng/ml versus 3762 +/- 890 ng/ml), and increased the number of cytoplasmic secretory granules per cell. These results indicate that hyperplastic pituitary and true pituitary neoplasms differ in their ability to grow readily after transplantation. The presence of S-100 protein-positive folliculostellate cells, which are present in hyperplastic but not in neoplastic pituitary tissues, may serve as a morphologic marker to separate hyperplastic and neoplastic rat pituitary tissues. Transplantable tumors remained responsive to estrogen with expression of a more differentiated phenotype, including an increased number of cells expressing PRL mRNA and increased numbers of PRL secretory granules.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1990

Analysis of endocrine active and clinically silent corticotropic adenomas by in situ hybridization.

The distribution of pro-opiomelanocortin (POMC) messenger RNA (mRNA) in 7 functional and 17 clinically silent corticotropic adenomas was analyzed by in situ hybridization (ISH) with 35S-labeled oligonucleotide probes using formalin-fixed paraffin-embedded tissue sections cut from blocks that were in storage between 1 to 14 years. All 7 functional adenomas and 4 subtype 1 tumors had detectable POMC mRNA, while 3 of 6 subtype 2 and 1 of 7 subtype 3 silent adenomas contained detectable POMC mRNA. In situ hybridization analysis with an 35S-labeled beta-actin probe showed a positive hybridization signal in 22 of 22 cases, indicating that the absence of detectable POMC mRNA in some adenomas was not due to loss of the mRNAs during processing of the tissues or because of the age of the embedded tissue blocks. Northern hybridization analysis with the oligonucleotide probes in 2 normal pituitaries and an adenoma causing Cushing's disease detected a 1.2-Kb mRNA in all three tissues, indicating that the oligonucleotide probes were very specific. These results indicate that subtype 1 silent adenomas and clinically active adenomas associated with Cushing's disease contain POMC mRNA that is readily detectable by ISH in routinely processed tissue specimens, while only a few of the subtypes 2 and 3 adenomas have POMC mRNA that can be detected in paraffin blocks with the oligonucleotide probes used in this study.

Adenoma↗

PubMed1990

[Membrane component of Shigella flexneri and their relationship to bacteria antigenicity and virulence].

Our previous works have shown that membrane proteins of S. flexneri can elicit protection against the bacteria in vivo. In this study, we further, using human convalescent sera (HCS) from adult patients infected with S. flexneri, investigated the relationship between membrane components of S. flexneri and their antigenicities and virulences. It was shown in immunoblotting that 5 virulent strains of S. flexneri and avirulent strain T32 derived from S. flexneri 2a by Istrati in Romania and used as a live vaccine, had three common proteins bands formed by the components of MW 67 kD, 63 kD and 60 kD with either HCS from patients infected with S. flexneri 2a and 3a or HCS absorbed by an avirulent variant strain 24570 of S. flexneri 2a, while virulent strains M90T and M25-8A (pWR110)minI shown another two bands of Mw 78 kD and 35 kD respectively. In contrast, no band was found with strain 24570. HCS from patients infected with S. flexneri 1a, 2a and 3a as well as those HCS absorbed by 24570 had blocking effect on the invasiveness of virulent strain of S. flexneri to the kerato conjunctiva of guinea pigs; nevertheless, HCS absorbed by T32 lost the blocking effect accompanied by disappearance of 67 kD, 63 kD and 60 kD components when T32 was used as antigen indicating that 67 kD, 63 kD and 60 kD membrane components of S. flexneri may account for the antigen of S. flexneri eliciting protection antibodies in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

[The diagnosable rate of beta-thalassemia in Chinese population and the strategy for selecting genetic markers in prenatal diagnosis of the disease].

It is possible to use some beta-thalassemia gene linkage markers for prenatal diagnosis of the disease currently. But there are some limitations due to incomplete linkage between these genetic markers and beta-thalassemia gene in population. The diagnosable rate of the genetic markers and their combinations have been calculated according to the polymorphism distribution data of the seven genetic markers in Chinese population. Then according to the diagnosable rate of each genetic marker and their combinations, the following is deduced: (1) Precedent estimation to the diagnosable rate of prenatal diagnosis; (2) Select the optimum strategy for prenatal diagnosis of beta-thalassemia suitable for Chinese population. In this paper, an optimum line is presented, regarding to select genetic markers for prenatal diagnosis of beta-thalassemia in Chinese population. Meanwhile, the method of gene linkage analysis and that of using oligonucleotide probe are compared.

Asian People↗

PubMed1990

Effects of propylthiouracil on growth hormone and prolactin messenger ribonucleic acids in the rat pituitary.

The effects of hypothyroidism induced by propylthiouracil (PTU) treatment on growth hormone (GH) and prolactin (PRL) messenger ribonucleic acid (mRNA) levels were analyzed in adult female rat adenohypophyses by in situ hybridization histochemistry and Northern hybridization analyses. Twenty-eight days of PTU treatment produced a significant decrease in GH mRNA levels and a smaller decrease in PRL mRNA determined by both in situ hybridization histochemistry and Northern hybridization analyses. A combined procedure of in situ hybridization histochemistry followed by immunochemistry on the same sections revealed mammosomatotropic cells expressing GH mRNA and PRL protein in the same pituitary cells from all treatment groups. Cells expressing GH mRNA and thyroid-stimulating hormone protein were not detected by this method. Immunochemical staining revealed a decrease in GH cells and an increase in thyroid-stimulating hormone cells in hypothyroid rats. Cells expressing both GH and thyroid-stimulating hormone protein were not detected by immunostaining. These results indicate that hypothyroidism produces significant decreases in GH mRNA and also decreases PRL mRNA and that mammosomatotropic cells can be detected in pituitaries from normal and hypothyroid rats.

Animals↗

PubMed1990

Ultrastructural localization of prolactin and chromogranin B messenger ribonucleic acids with biotinylated oligonucleotide probes in cultured pituitary cells.

A technique for the subcellular localization of prolactin and chromogranin B messenger RNAs (mRNA) in pituitary adenomas by in situ hybridization with biotinylated oligonucleotide probes is described. Ultrastructural examination revealed clusters and individual gold particles in the cytoplasm with this pre-embedding in situ hybridization method. Prolactinomas expressed both prolactin and chromogranin B mRNA, whereas the null cell adenoma expressed only chromogranin B mRNA. Sections of positively labeled cells contained up to 30 gold particles/cell. Treatment of cells with RNAse before hybridization reduced the number of gold particles to less than 1/cell. These results indicate that biotinylated oligonucleotide probes can be used to localize different mRNAs in cultured pituitary cells at the ultrastructural level to study the processing of these molecules within specific cells and for more precise correlation of molecular function with ultrastructural morphology.

Adenoma↗

PubMed1989

Effects of estradiol on prolactin and growth hormone messenger RNAs in cultured normal and neoplastic (MtT/W15 and GH3) rat pituitary cells.

The effects of 17 beta-estradiol (E17 beta) on prolactin (PRL) cell proliferation and on the expression of PRL and growth hormone (GH) proteins and mRNAs were analyzed in cultured pituitary cells by immunocytochemistry, in situ hybridization, and Northern blot hybridization studies. Three different cell cultures were used: (a) normal pituitary cells; (b) GH3 tumor cell line; and (c) MtT/W15, a transplantable PRL and GH-producing pituitary tumor. E17 beta (10(-7) M) caused a significant increase in PRL cell proliferation in normal pituitary [3.9 +/- 0.4 versus 7.7 +/- 0.9% (SEM) of immunostained PRL cells with thymidine incorporation] [P less than 0.01] but produced a significant decrease in PRL cell proliferation in MtT/W15 primary cell cultures [6.7 +/- 1.0 versus 3.7 +/- 0.8%] [P less than 0.05]. PRL mRNA was significantly increased in normal pituitary and in GH3 tumor cells by E17 beta treatment. There was a significant decrease in PRL mRNA and an increase in GH mRNA expression in cultured MtT/W15 tumor cells by immunocytochemistry and in situ hybridization analyses. The percentage of cells producing both PRL and GH or mammosomatotropic cells analyzed by two different techniques declined after one week in culture in normal pituitary cells and in cultured MtT/W15 tumor cells after E17 beta treatment. These results show that E17 beta has a direct stimulatory effect on normal pituitary and GH3 cells and a direct inhibitory effect on MtT/W15 tumor cells with respect to cell proliferation and PRL hormone and mRNA expression.

Animals↗