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Biomedical subjects

T Sun

Publications and source records attributed to T Sun.

At least 109 records · Page 6Linked to original sources
PubMed1997

Reinterpretation of the RACTK1 K+ channel.

The RACTK1 cDNA cloned from rabbit kidney cortical collecting duct cells was associated with inwardly rectifying pH-regulated K+ channel activity (M. Suzuki, K. Takahashi, M. [keda, H Hayakawa, A. Ogawa, Y. Kawaguchi, and O. Sakai. Nature Lond. 367: 642-645, 1994). The deduced amino acid sequence of the encoded novel polypeptide lacked the signature sequence of a K(+)-selective pore region but predicted a topography suggestive of the inward rectifier K+ channel family. In subsequent articles a RACTK1 epitope was immunolocalized to the apical surface of kidney collecting duct and to arteriolar smooth muscle [M. Suzuki, T. Takigawa, K. Kimura, C. Koseki, and M. Imai. Am. J. Physiol. 269 (Cell Physiol, 38): C496-C503, 1995], and apamin-sensitive K+ currents displaying Ca(2+)-dependent and voltage-independent activation accompanied stable heterologous overexpression of RACTK1 [M. Suzuki, M. Murata, M. Ikeda, T. Miyoshi, and M. Imai. Am. J. Physiol. 270 (Cell Physiol, 39): C964-C968, 1996]. We now report that the "RACTK1" open reading frame is a frame-shifted translation of the antisense strand of an Escherichia coli gene member of a coenzyme A transferase gene family. "RACTK1" mRNA was absent from tissues free of E. coli contamination, and the "RACTK1" gene was undetectable in Southern blots of human and rabbit genomic DNA. We conclude that the immunostaining patterns and Ca(2+)-activated K+ channel activity heretofore attributed to RACTK1 must be otherwise explained.

Animals↗
PubMed1997

[High-methylprednisolone treatment in acute cervical spinal cord injury without fracture and dislocation].

We compared methylprednisolone (MP), surgical decompression and both in acute cervical spinal cord injury without fracture and dislocation. The study involved 32 acute cervical spinal cord injury without fracture and dislocation. MP was given to 8 cases (high-MP group) within 8 hours after injury. 12 cases (surgical group) underwent surgical decompression (anterior or posterior approach) within 48 hours after injury. 12 cases (combined group) were treated with MP within 8 hour of their injury and surgical decompression within 48 hours after injury. Neurological function was assessed using scores according to international standards for neurological and functional classification of spinal cord injury. The results showed that combined group were more effective than high-MP or surgical group, in the complete or incomplete spinal cord injury, and in motor and sensory. The risk of such complication as gastrointestinal bleeding or delayed wound healing is not significant with using high-MP.

Aged↗
PubMed1997

[Water vapor permeability measurement of the materials used as a wound covering].

This paper introduces a new apparatus and method that suits to measuring the water vapor transmission rate (WVTR) of wound covering materials. WVTR of synthetic materials, amniotic membrane, porcine and cadaveric skin was measured under different conditions of four temperatures, three mediums, and "water cup" or "inverted water cup". The temperature was in close relationship with the WVTR except Omiderm, amniotic membrane, and cadaveric skin between 30 degrees C and 37 degrees C groups. The medium did not affect the WVTR (P > 0.05). There was significant difference between the "water cup" and "inverted water cup" groups(P < 0.01). This study suggests that the apparatus is easy-to-operate, reliable and suitable for the measurement of WVTR of burn wound coverings and other membranous materials.

Bandages↗
PubMed1997

[Human dynamic equations and analysis of opening the hatch door under weightlessness].

The general human dynamic equations under weightlessness were derived using Kane-Huston's Method. According to manned spaceflight circumstances, specific equations for models of floating in space and having a single point support were derived from the above general equations. The action that the astronaut opens the hatch door was analyzed, the "float" evolution was calculated, and the evolutionary curves were drawn.

Anthropometry↗
PubMed1997

Aromatase expression in health and disease.

Family 19 of the P450 superfamily is responsible for the conversion of C19 androgenic steroids to the corresponding estrogens, a reaction known as aromatization, since it involves conversion of the delta 4-3-one A-ring of the androgens to the corresponding phenolic A-ring characteristic of estrogens. Its members occur throughout the entire vertebrate phylum. The reaction mechanism of aromatase is very interesting from a chemical point of view and has been studied extensively; however, a detailed examination of structure-function relationships has not been possible due to lack of a crystal structure. Recent attempts to model the three-dimensional structure of aromatase have permitted a model that accounts for the reaction mechanism and predicts the location of aromatase inhibitors. The gene encoding human aromatase has been cloned and characterized and shown to be unusual compared to genes encoding other P450 enzymes, since there are a number of untranslated first exons that occur in aromatase transcripts in a tissue-specific fashion, due to differential splicing as a consequence of the use of tissue-specific promoters. Thus, expression in ovary utilizes a proximal promoter that is regulated primarily by cAMP. On the other hand, expression in placenta utilizes a distal promoter that is located at least 40 kb upstream of the start of transcription and that is regulated by retinoids. Other promoters are employed in brain and adipose tissue. In the latter case, class I cytokines such as IL-6 and IL-11 as well as TNF alpha are important regulatory factors. PGE2 is also an important regulator of aromatase expression in adipose mesenchymal cells via cAMP and PGE2 appears to be a major factor produced by breast tumors that stimulates estrogen biosynthesis in local mesenchymal sites. In all of the splicing events involved in the use of these various promoters, a common 3'-splice junction is employed that is located upstream of the start of translation; thus, the coding regions of the transcripts- and hence the protein-are identical regardless of the tissue site of expression; what differ in a tissue-specific fashion are the 5'-ends of the transcripts. This pattern of expression has great significance both from a phylogenetic and ontogenetic standpoint as well as for the physiology and pathophysiology of estrogen formation. Recently, a number of mutations of the aromatase gene have been described, which give rise to complete estrogen deficiency. In females this results in virilization in utero and primary amenorrhea with hypergonadotropic hypogonadism at the time of puberty. In men the most striking feature is continued linear bone growth beyond the time of puberty, delayed bone age, and failure of epiphyseal closure, thus indicating an important role of estrogens in bone metabolism in men. In both sexes the symptoms can be alleviated by estrogen administration.

Amino Acid Sequence↗
PubMed1997

Regulation of aromatase expression in the ovary and placenta: a comparison between two species.

The conversion of C19 steroids to estrogens is catalysed by aromatase P450 (P450arom; product of the CYP19 gene). Tissue sites of expression include the gonads and brain; however, in a small subset of mammals, P450arom is also expressed in the placenta. In humans, gonadal expression employs a promoter proximal to the start site of translation, whereas expression in the placenta relies on a promoter which is distal to this site. We characterized the bovine CYP19 gene in both the ovary (OV) and placenta (PL), to determine if this method of regulation of tissue-specific expression is employed in other species. Both bovine and human species express P450arom in these tissues, however, the pattern of expression is very different. In both humans and cattle, P450arom is expressed in the granulosa cells of the ovary, however, after ovulation only the luteinized granulosa cells of the human continue to express P450arom. There is a high degree of sequence identity (>70%) shared between humans and cattle in the OV-specific 5'-flanking DNA, whereas little identity (<40%) was found between humans and cattle in the PL-specific DNA. Promoters and 5'-flanking regions of human and bovine CYP19 genes were subcloned into a luciferase (LUC) vector. Bovine PL-specific constructs transfected into JEG-3 human choriocarcinoma cells failed to express LUC activity. When OV-specific constructs were transfected into luteinized bovine granulosa cells, there was no change in LUC activity in cells transfected with the bovine constructs after treatment with forskolin, whereas all of the corresponding human constructs expressed LUC activity. The bovine 5'-flanking DNA lacks a cAMP-responsive element-like sequence (CLS) critical for cAMP-stimulated transcription of P450arom in the human ovary. With the absence of this CLS sequence in the bovine gene, there appears to be little enhancement of transcription by cAMP in the portion of the 5'-flanking region studied so far. When the analogous region of the bovine promoter was mutated to the human CLS, only a partial restoration of LUC activity was observed. An additional element therefore appears to be important in preventing the full expression of the bovine CYP19 gene in luteinized granulosa cells.

Animals↗
PubMed1997

[Effects of bFGF on succinate dehydrogenase level and oxygen consumption of skin flap in rats].

To investigate the effects of basic fibroblast growth factor (bFGF) on necrosis rate, succinate dehydrogenase level and oxygen consumption of the skin flap, 18 Wistar rats were divided into 2 groups. Caudally based skin flap was raised on the back of each rat. Nine micrograms bFGF or normal saline with heparin was instilled under the flaps respectively after closure of the wounds. After 7 days, the necrosis rate of each wound was measured. The result showed that in bFGF group, the average necrosis rate of skin flap was 18.2%, less than that of the control group (37.14%). Succinate dehydrogenase content and oxygen consumption in bFGF group were higher than those of the corresponding sites in the control group (P < 0.05). It was suggested that the use of bFGF resulted in the decrease rate of necrosis of skin flap, and it maintained higher succinale dehydrogenase level and oxygen consumption. It was concluded that bFGF would probably be valuable for clinical use.

Animals↗
PubMed1996

Relationship between hairy cell leukemia variant and splenic lymphoma with villous lymphocytes: presentation of a new concept.

An unusual case of low-grade B-cell lymphoproliferative disorder with peripheral lymphocytosis and splenomegaly followed for 4 1/2 years is reported. During this period, the phenotype of the tumor cells in the blood changed from that of hairy cell leukemia (HCL)/chronic lymphocyte leukemia (CLL) to HCL/prolymphocytic leukemia (PLL), to PLL. The lymphoid population in the blood showed a mixture of hairy cells, villous lymphocytes, small lymphocytes, and prolymphocytes, corresponding to the phenotypes at various stages. Although relatively specific markers for CLL, HCL, and PLL, such as CD5, CD11c, CD22, CD25, and FMC-7, were positive at various stages, all these markers have also been demonstrated in a large study series of splenic lymphoma with villous lymphocytes (SLVL). In addition, the histologic pattern of the bone marrow biopsy and splenectomy specimen were not typical for HCL. This case can therefore be classified either as HCL variant or as SLVL. As SLVL assumes various cytologic and histologic patterns, which overlap with different lymphoproliferative disorders, especially HCL variants, this entity appears to represent a heterogeneous group of lymphomas/leukemias that may evolve into each other. The absence of activation of c-myc and bc1-2 oncogenes as well as mutation of p53 tumor suppressor gene, together with the presence of only one single rearranged band for both heavy chain and kappa light chain genes in our case suggest that these morphologically different lymphoid tumors may belong to the same family.

Antigens, CD↗
PubMed1996

Melanoma awareness and self-examination practices: results of a United States survey.

BACKGROUND: Skin cancers are common and there has been a dramatic increase in their incidence, particularly melanoma. However, little is known about awareness of melanoma and early detection practices in the general U.S. population. OBJECTIVE: In 1995, the American Academy of Dermatology increased their efforts to promote awareness of melanoma. This study was conducted to document current knowledge of melanoma and self-examination practices. METHODS: In February 1995, a telephone survey was conducted in a nationally representative sample of 1001 persons at least 18 years of age (3% margin of error) that included questions on knowledge, attitudes, and practices regarding early detection of melanoma. RESULTS: Almost 42% of those surveyed were unaware of melanoma, and only 26% of those who were aware could identify its specific signs. Most recognized at least one common risk factor for melanoma (e.g., sun exposure, fair skin). However, many did not distinguish melanoma from other skin cancers in terms of risk factors, signs of early disease, and body site distribution. The lowest measures of melanoma knowledge and attitudes were found among those who are male, nonwhite, and parents, and those with the lowest level of education and income. More than half (54%) did not conduct a self-examination. This practice was most frequently reported by women, white persons, and the elderly, as well as those with a greater knowledge of melanoma. CONCLUSION: Our research documents deficiencies in knowledge and practices related to early detection of melanoma in the general U.S. population and supports the need for public education about melanoma.

Adult↗
PubMed1996

Evaluation of the American Academy of Dermatology's National Skin Cancer Early Detection and Screening Program.

BACKGROUND: Increasing incidence and mortality rates from cutaneous melanoma are a major public health concern. As part of a national effort to enhance early detection of melanoma/skin cancer, the American Academy of Dermatology (AAD) has sponsored an annual education and early detection program that couples provision of skin cancer information to the general public with almost 750,000 free skin cancer examinations (1985-1994). OBJECTIVE: To begin to evaluate the impact of this effort, we determined the final pathology diagnosis of persons attending the 1992-1994 programs who had a suspected melanoma at the time of examination. METHODS: We directly contacted all such persons by telephone or mail and received pathology reports from those who had a subsequent biopsy. RESULTS: We contacted 96% of the 4458 persons with such lesions among the 282,555 screenings in the 1992-1994 programs. We obtained a final diagnosis for 72%, and the positive predictive value for melanoma was 17%. Three hundred seventy-one melanomas were found in 364 persons. More than 98% had localized disease. More than 90% of the confirmed melanomas with known histology were in situ or "thin" lesions (< or = 1.50 mm thick). The median thickness of all melanomas was 0.30 mm. The 8.3% of AAD cases with advanced melanoma (metastatic disease, regional disease, or lesions > or = 1.51 mm) is a lower proportion than that reported by the 1990 Surveillance, Epidemiology and End Result Registry. The rate of thickest lesions (> or = 4 mm) and late-stage melanomas among all participants was 2.83 per 100,000 population. Of persons with a confirmed melanoma, 39% indicated (before their examination) that without the free program, they would not have considered having a physician examine their skin. CONCLUSION: The 1992-1994 free AAD programs disseminated broad skin cancer educational messages, enabled thousands to obtain a free expert skin cancer examination, and found mostly thin, localized stage 1 melanomas (usually associated with a high projected 5-year survival rate). Because biases impose possible limitations, future studies with long-term follow-up and formal control groups should determine the impact of early detection programs on melanoma mortality.

Adult↗
PubMed1996

Light and electron microscopic identification of Cyclospora species in the small intestine. Evidence of the presence of asexual life cycle in human host.

This is the first case of cyclosporiasis in which the parasite was clearly demonstrated in a duodenal biopsy by light microscopy. Electron microscopy identified the stages of sporozoite, trophozoite, schizont, and merozoite. Although only asexual forms were identified in our case, the sexual cycle must have taken place in the human host, because oocysts were detected in stools of the patients. Therefore, it appears that Cyclospora species require only a single host to complete its entire life cycle. Despite the heavy infection, only enterocytes were invaded. The lamina propria and submucosa were not involved. The morphology of Cyclospora in the intestine is similar to that of Isospora, but differs from that of Cryptosporidium. The morphology of the oocyst of Cyclospora resembles that of Cryptosporidium, but differs from that of Isospora. Thus, a combined study of both stool and intestinal biopsy should readily distinguish Cyclospora from Cryptosporidium and Isospora.

AIDS-Related Opportunistic Infections↗
PubMed1996

Analysis of impact of rigid projectiles on compound targets.

We developed a model to simulate a person, with and without protective armor, being subjected to an impact of a high speed, rigid projectile. The complex nature of the head and chest are simulated in our layered, spaced, various thickness targets made of different materials. A rigid projectile-target interaction model is described. Target resistance force was obtained from a generalized Poncelet equation. Good agreement between observed and computed penetration phenomena was obtained.

Computer Simulation↗
PubMed1996

[Studies on peptide. XIX: Hepatitis C virus (HCV) immune selection].

HCV has characteristics of rapid variability. The amino terminus of E2/NS1 of HCV (amino acids sequence 384-414), which is hypervariable with respect to both nucleotide and amino acid sequence, has been termed the E2 HV domain or HVR1. The E2 HV domain appears to be a rapidly evolving region of the HCV genomes which may contain linear neutralizing epitopes and the E2 HV are under immune selection. For further studies of the immunogenicity on E2 HV of HCV, we selected three peptide fragments from the full length of E2 HV region sequence and synthesized them with SPPS method. The amino acid sequences are shown as following: P2: VDGDTHVTGGAQAKTTNR (381-398); P9: STHVTGAVQGHSIRGTTSLFTSGPAQKIQ (384-412); P10: RTYTSGGTAGHTTSGITSLFSPGASQKIQ (384-412). From the results of ELISA and anti-peptide Abs of rabbit sera, we conclude that there are anti-E2 HV Abs in immune host but they could not neutralize HCV, so these Abs were not reactive with all E2 HV epitopes that resulted in immune selection of escape mutants; the anti-E2 HV Abs, probably from the same genotype, contained some common structure in which E2 HV epitopes react with other anti-E2 HV Abs at 30%: the C-terminus of E2 HV region (398-412) caused the immune response to rabbits.

Amino Acid Sequence↗
PubMed1996

[Effect of recombinant human epidermal growth factor on the expansion of human skin in vitro].

We investigated the effect of the different concentrations of recombinant human epidermal growth factor (rhEGF) on the expansion of human skin in vitro. Pieces of skin about 2 mm2 in area were placed in 24-cell wells and rhEGF in different concentrations was added. The wells were incubated at 37 degrees C in 5% CO2 for 4 d. The expanded area of each piece of skin was measured. The results indicated that rhEGF possessed a regulating effect on the expansion of skin pieces, and the expanded area was parabolically related with the concentrations of rhEGF. When the rhEGF concentration reached 5 micrograms/L, the maximal area expansion (7.08 +/- 2.40 mm2) was found, which was as twice as the area in control group (3.63 +/- 1.98 mm2). It was suggested that rhEGF had a potential therapeutic effect in wound healing.

Cell Division↗
PubMed1996

[Clinical pathological study on 23 pulmonary embolism proved by autopsy].

OBJECTIVE: To improve the early diagnosis of pulmonary embolism. METHODS: The clinical and pathological data of 23 cases of autopsy-proved pulmonary embolism in Beijing hospital from 1951 to 1994 were reviewed. RESULTS: 23 patients: male 18, female 5, age ranged from 34 to 82 years. Misdiagnosis rate was 87%. The unexplained dyspnea, chest pain, sudden onset dyspnea and sudden death were the most frequent symptoms. Arterial blood gas data frequently demonstrated hypoxia and hypocapnia. The most important causes of an incorrect diagnosis could be the failure of suspecting pulmonary embolism, because of the variability of clinical manifestation and the presence of other concomitant diseases. CONCLUSION: All patients with otherwise severe unexplained dyspnea or chest pain have to be sent for perfusion lung scintigraphy, accordingly, underdetection of pulmonary embolism and mortality of pulmonary embolism could be reduced.

Adult↗
PubMed1995

Acute agranular CD4-positive natural killer cell leukemia. Comprehensive clinicopathologic studies including virologic and in vitro culture with inducing agents.

BACKGROUND: A 63-year-old male presented with fever, a subcutaneous nodule, gingival hypertrophy, lacrimal gland enlargement, and no lymphadenopathy or hepatosplenomegaly, but had anemia, thrombocytopenia, and peripheral blood (PB) plus bone marrow (BM) involvement by leukemic cells. There was minimal response to multiagent chemotherapy and local radiotherapy, with a survival of 6.5 months from disease diagnosis. METHODS: The PB and/or BM leukemic cells were evaluated using electron microscopy (EM), immunohistochemistry, flow-cytometric immunophenotyping, cytochemistry, cytogenetics, Southern blot analysis for gene rearrangement and Epstein-Barr virus (EBV), polymerase chain reaction for EBV and human herpes virus-6 (HHV-6), and in vitro culturing with inducing agents. RESULTS: The leukemic cells were agranular and monocytoid, with a hairy cell-like bone marrow biopsy infiltrate. Myeloperoxidase (MPO) and alpha-naphthyl butyrate esterase staining was negative, and periodic acid-Schiff staining was positive by light microscopy. Electron microscopy showed MPO negativity and a lack of parallel tubular arrays. The immunophenotype was CD3-, CD56+, CD4+, CD8-, CD15+, TCR1-, and TCR2-, with germline immunoglobulin and T-cell receptor genes and an abnormal karyotype (44XY, 5q-, -13, 13q+, -15). No genomic material for EBV or HHV-6 was detected. Cell cultures with butyrate and N,N-hexamethylene bis-acetamide suggested the possible induction of tumor cells to express a T-cell immunophenotype. CONCLUSION: A case of clonal acute natural killer (NK) cell leukemia with an unusual morphology (agranular) and unique phenotype (CD3-, CD56+, CD4+, CD15+) is presented. Unlike as in other acute NK leukemias, EBV was negative; there was no evidence of HHV-6. The tumor cell, after culturing with differentiating agents, may have been induced to express a T-cell immunophenotype.

Acetamides↗
PubMed1995

Frog cytochrome P-450 (11 beta,aldo), a single enzyme involved in the final steps of glucocorticoid and mineralocorticoid biosynthesis.

A cDNA for cytochrome P-450(11 beta,aldo) was cloned from a library of bullfrog interrenal tissue (tissue corresponding to the mammalian adrenal gland). The 1919-bp cDNA encoded a protein of 517 amino acids. Its amino acid sequence was highly similar to the sequences of bovine P-450(11 beta) and rat P-450(11 beta,aldo) when P-450(11 beta) family enzymes reported to date were examined. The enzyme expressed in COS7 cells had the 11 beta-hydroxylation, 18-hydroxylation activities and aldosterone synthetic activity. Northern-blot and immunoblot analyses suggested that a single P-450(11 beta) enzyme was expressed in bullfrog interrenal tissue. These results suggest that a single enzyme catalyzes the final steps of glucocorticoid and mineralocorticoid biosynthesis in bullfrog interrenal tissue as in bovine adrenal gland. A phylogenetic tree of CYP11B genes suggests that the frog enzyme diverged at an earlier evolutionary time from other vertebrate enzymes. Immunohistochemical and in situ hybridization studies indicated that steroidogenic cells existed in the outer region of interrenal tissue more densely than in the inner region, whereas some medullary cells made clusters like islets. Most of the cells were diffusely distributed in the tissue.

Amino Acid Sequence↗