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Biomedical subjects

S Y Lu

Publications and source records attributed to S Y Lu.

At least 19 recordsLinked to original sources
PubMed1992

Magnetic resonance imaging of neural transplants in rat brain using a superparamagnetic contrast agent.

Rat fetal brain tissue was incubated in vitro with superparamagnetic ferrite particles covalently coupled to the lectin wheat germ agglutinin (WGA) and transplanted into the adult rat striatum. At 6 days and at 3 weeks post-surgery the transplants were observed on T1 weighted magnetic resonance (MR) images of the rat head as an area of relatively low signal intensity which could be clearly differentiated from the higher signal intensity produced by the host brain. Histological analysis revealed that the ferrite particles were largely restricted to the transplant in a patchy distribution. The ferrite particles were associated with cells having an apparent normal morphology. Superparamagnetic ferrite particles act as potent MR contrast agents and can be used to label transplanted cells. The labeled cells are apparently not adversely affected by the WGA-ferrite particles and can be monitored for at least three weeks in vivo using noninvasive MR imaging.

Animals↗
PubMed1992

Adaptation of gastric mucosa to chronic alcohol administration is associated with increased mucosal expression of growth factors and their receptor.

In our previous study we found that chronic, intragastric administration of ethanol to rats produces adaptation of the gastric mucosa to subsequent challenge with an acute dose of 50% ethanol. The mechanism of this mucosal tolerance remains unexplained. Epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) stimulate cells growth and proliferation in the gastric mucosa with noted trophic effect, protect the gastric mucosa against acute injury and accelerate healing of injured mucosa. Many of these effects are exerted through EGF and TGF alpha action on their common receptor (EGFR). The aim of the present study was to determine the effect of chronic alcohol administration on cell proliferation and gastric mucosal expression and distribution of EGF, TGF alpha and EGFR. Chronic administration of ethanol (1 ml, 50% ethanol, twice daily) significantly increased the extent of gastric mucosal mucous and proliferative cell zones, the number of proliferating (DNA synthesizing) cells and mucosal expression of EGF, TGF alpha and EGFR by 13, 6, and 20-fold, respectively. Thus, adaptation of gastric mucosa to chronic alcohol administration is associated with increased cell proliferation and increased expression of mucosal EGF, TGF alpha and EGFR.

Adaptation, Physiological↗
PubMed1991

Striatal, ventral mesencephalic and cortical transplants into the intact rat striatum: a neuroanatomical study.

Intrastriatal transplantation of fetal striatal (STR), cortical (CTX), or ventral mesencephalic (VM) tissue into the normal striatum has been shown to produce behavioral deficits (38). Here, we have examined the cellular elements of the transplants and their connectivity with the host using histochemistry for cytochrome oxidase (CO) and acetylcholinesterase (AChE), immunocytochemistry for glial fibrillary acidic protein (GFAP), OX42, tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), serotonin (5-HT), and cholecystokinin (CCK). Autoradiography for dopamine D1 and D2, muscarinic cholinergic, and serotonin 5-HT1 and 5-HT2 receptors at 5-15 months after transplantation was also investigated. CO staining showed that all transplants were metabolically active. The STR and VM transplants contained AChE-positive neurons and fibers. The CTX transplants exhibited AChE terminals with an appearance similar to that of the host cortex. AChE staining within the STR transplants was patchy. 5-HT-, TH-, and DBH-immunoreactive (IR) fibers were found in the STR and CTX transplants. In two of six CTX transplants, many TH-IR neurons were present. The VM transplants contained many TH-IR, 5-HT-IR, and DBH-IR cell bodies and fibers. CCK-IR stain was found in the VM transplant and was coextensive with regions containing TH-IR cell bodies. Fibers stained by all markers crossed the transplant and host border. Receptor autoradiography revealed that muscarinic cholinergic and 5-HT2 receptors were present in the STR, CTX, and VM transplants. In addition, dopamine D1 and D2 receptors were present in the STR transplants. Intermittent heavy staining for GFAP and OX42 were observed along the border of most transplants and the hosts. It was noted that high densities and hypertrophy of GFAP- or OX42-stained astrocytes or microglia, respectively, were present in the transplants and adjacent host. OX42-stained macrophages were found in many transplants. The present results indicate that intrastriatal transplants into the intact normal brain express numerous histochemical, immunocytochemical, and receptor features characteristic of the appropriate adult tissues. The afferents from the host extend into the STR and CTX transplants, and neural fibers from the VM transplants grew into surrounding host tissue, suggesting possible anatomical connection. Ultrastructural evidence is needed to determine if these fibers form synaptic connections. The results from GFAP and OX42 immunocytochemical staining support the possibility suggested by behavioral studies that damage to the host brain is induced by neural transplantation.

Acetylcholinesterase↗
PubMed1991

A G-string positive cis-regulatory element in the LpS1 promoter binds two distinct nuclear factors distributed non-uniformly in Lytechinus pictus embryos.

The LpS1 alpha and beta genes of Lytechinus pictus are activated at the late cleavage stage of embryogenesis, with LpS1 mRNAs accumulating only in lineages contributing to aboral ectoderm. We had shown previously that 762 bp of 5' flanking DNA from the LpS1 beta gene was sufficient for proper temporal and aboral ectoderm specific expression. In the present study, we identified a strong positive cis-regulatory element at -70 bp to -75 bp in the LpS1 beta promoter with the sequence (G)6 and a similar, more distal cis-element at -721 bp to -726 bp. The proximal 'G-string' element interacted with two nuclear factors, one specific to ectoderm and one to endoderm/mesoderm nuclear extracts, whereas the distal G-string element interacted only with the ectoderm factor. The ectoderm and endoderm/mesoderm G-string factors were distinct based on their migratory behavior in electrophoretic mobility shift assays, binding site specificities, salt optima and EDTA sensitivity. The proximal G-string element shared homology with a binding site for the mammalian transcription factor IF1, a protein that binds to negative cis-regulatory elements in the mouse alpha 1(I) and alpha 2(I) collagen gene promoters. Competition experiments using wild-type and mutant oligonucleotides indicated that the ectoderm G-string factor and IF1 have similar recognition sites. Partially purified IF1 specifically bound to an oligonucleotide containing the proximal G-string of LpS1 beta. From our results, we suggest that the ectoderm G-string factor, a member of the G-rich DNA-binding protein family, activates the LpS1 gene in aboral ectoderm cells by binding to the LpS1 promoter at the proximal G-string site.

Animals↗
PubMed1991

[Studies of mtDNA of Ustilago maydis. I. Cloning and gene mapping].

This paper covers the following studies of mtDNA of Ustilago maydis. (1) By inserting the Bam HI and Pst I fragments of the mtDNA into the corresponding sites of pBR322, we cloned a unique sequence of 49.6 kb, accounting for 89.3% of the mitochondrial genome (60.7 kb). (2) With heterogenous genes from plants or fungi as probes, we identified seven genes, and mapped them onto the restriction map of the mt DNA. The genes were arranged in such an order: -UmCOB-UmOXII-S-rR NA-UmOXIII-L-rRNA-UmATPase6-UmOXI-. (3) We tried to express the three cloned genes, UmOXII, UmOXIII, and Um-ATPase 6, in E. coli maxcel expression system, but no specific protein was observed.

Chromosome Mapping↗
PubMed1991

[Studies on mtDNA of Ustilago maydis. II. Restriction mapping].

A restriction map was constructed for mtDNA of Ustilago maydis. The fragment order for each restriction enzyme was determined by DNA hybridization and fragment overlapping. The restriction sites were located by analysing the secondary digestions of the cloned mtDNA fragments. It was also found that the mtDNA of U. maydis was a circle molecule (60.7 kb), without recognizable repeat sequence.

DNA, Mitochondrial↗
PubMed1991

Mandible metastasis as the initial manifestation of breast carcinoma--report of a case.

A case is presented in which the only positive subjective and clinical findings were numbness of the lower lip and chin, generalized tooth mobility with dull pain, and swelling of the right lower jaw. After an appropriate and careful workup, in conjunction with other medical colleagues, a definitive diagnosis of adenocarcinoma of breast metastasis to the mandible was made, which was confirmed by a histopathologic examination. Radiographs disclosed radiolucent change with an irregular and a moth-eaten appearance in the mandibular trabeculation and loss of the lamina dura of several teeth. As this case demonstrates, the diagnosis of metastatic disease of the jaws requires a high degree of diagnostic astuteness, because of the many possible clinical signs and symptoms which can be nonspecific and can resemble diseases of an inflammatory origin. Accordingly, a histologic evaluation is essential in establishing a definitive diagnosis. The case report emphasizes the need for consideration of metastatic disease in the differential diagnosis of unknown oral lesions, especially in the mandible.

Adenocarcinoma↗
PubMed1990

Behavioral effects of neural transplants into the intact striatum.

The behavioral effects of fetal brain tissue and adrenal medulla transplants into the intact striatum of rats were investigated. Following a bilateral injection of 1.5, 3 or 6 microliters of fetal striatal tissue, a volume-related weight loss was found in all transplanted groups, including the SHAM group, during the first 7 days after the surgery. Rearing behavior was changed in a transplant volume-related manner. Histological analysis suggested that the locomotor effects of transplants into the intact striatum are related to the volume of the transplants. Following bilateral transplantation of fetal cortex (CTX), substantia nigra (SN), striatum (STR), or adrenal medulla (AM) into the striatum, the different behavioral deficits were observed among these transplant groups. The SN group showed a decrease in spontaneous locomotion, significantly increased rearing activity in response to administration of amphetamine, reduction of food intake and water intake and a reduction in body weight. The CTX and AM groups showed a marked increase in spontaneous rearing activities. Hyporesponsiveness to the administration of apomorphine (1 mg/kg) and amphetamine (1 mg/kg) was evident in the CTX, STR, AM groups and SHAM groups. In contrast, the haloperidol-induced catalepsy scores of the CTX, STR, SN and AM were significantly higher than those of a normal control group. In addition, the CTX group showed a deficit in the delayed reward alternation test. These results indicated that the behavioral deficits produced by transplants into normal striatum may be related to both mechanical destruction due to transplant expansion and specific neurochemical interactions of each tissue type between the host and the transplant. Therefore, potential negative consequences of neural transplantation therapy should be considered as well as the beneficial effects.

Animals↗
PubMed1990

Bilateral Warthin's tumors in a Chinese--literature review and case report.

Warthin's tumor is an unusual benign salivary gland tumor. It is predominantly found in Caucasians and is rare in non-Caucasians. The chief affected area of the tumor is the parotid gland. Of all salivary gland neoplasms, Warthin's tumor is the only lesion which is truly multicentric so it may have a second primary lesion, not a recurrence. The peak incidence is in the sixth decade of life. In sexual distribution, there is a male predominance but the incidence of female is progressively increasing. According to Lemelas's study, the increase in female incidence may relate to the increasing population of cigarette smoking of women. Bilateral parotid gland involvement is uncommon. The chief treatment of the tumor is surgical excision. The surgical methods include enucleation, superficial parotidectomy, total parotidectomy. It is very important to protect the facial nerves from injury during surgery. In this paper, we report a case of bilateral metachronous Warthin's tumors with cystic degeneration of parotid glands in a Chinese. Other than literature review and case report, four different methods to protect facial nerves from injury were briefly described.

Adenolymphoma↗
PubMed1989

Multilocus linkage analysis with the human argininosuccinate synthetase gene.

We have identified three restriction fragment length polymorphisms (RFLPs) from within the argininosuccinate synthetase (ASS) gene which maps to human chromosome 9q34-qter. Although RFLPs at pseudogene loci are detected by the cDNA, these are the first polymorphisms reported at the ASS locus. The three RFLPs are in linkage equilibrium with each other, and haplotypes for the ASS locus are highly informative. Two-locus recombination estimates between ASS and seven other 9q markers indicated that ASS is closest to the ABO blood group with a recombination fraction of 0.04 (0.005-0.11). A multilocus lod score analysis with these seven 9q markers indicated that ASS maps between ABL and MCT136 close to ABO, but it is uncertain if ASS is centromeric or telomeric to ABO.

Alleles↗
PubMed1989

The rehabilitation of pressure sores after myocutaneous flap surgery.

Fourteen myocutaneous flap operations for the treatment of pressure sores were performed from June 1984 to May 1986. After surgery, the patient was immobilized in a prone position in order to avoid direct pressure on the flap and to minimize motion of the hips. When the daily drainage from the wound was less than 10ml, the drain was removed. Hip flexion and body turning every 2 hours (except direct pressure on the flap) were started the day after the removal of the drain. In the meanwhile, a 2-5kg sandbag was placed on the flap until the flap showed mild redness which disappeared within 10 minutes. Under close observation, the duration increased step by step till the flap could tolerate compression for 2 hours continuously. Then the patient was allowed to assume a position with the body weight directly on the flap. Each session of pressure training lasted only until the flap showed mild redness and faded away quickly. The pressure training was finished when the flap was able to tolerate the patient's body weight for approximately 2 hours. The results showed that the myocutaneous flap could bear weight as normal skin 18.5 +/- 5.3 days after the operation; the average duration of hospitalization for treating one sore with a myocutaneous flap was 28.2 +/- 8.7 days. The time involved in pressure training after a myocutaneous flap operation may progress more quickly than that after a conventional skin flap operation.

Adult↗
PubMed1985

Identification of lactate dehydrogenase-M polypeptide translated in vitro from human and mouse tumor cell poly(A)-containing messenger RNA.

Rabbit anti-human lactate dehydrogenase-5(M4) antisera were raised which cross-reacted with mouse lactate dehydrogenase M polypeptide. The antisera were used for identification of human and mouse LDH-M polypeptides synthesized using an in vitro system directed by the mRNAs. The in vitro translation products directed by both mRNAs were similar in size and immunologically identical to the authentic LDH-M polypeptides. The sizes of the mRNAs encoding for both human and mouse LDH-M polypeptides were similar, about 15S (1445 nucleotides) and were shorter than the corresponding rat mRNA which is about 18S (1765 nucleotides).

Animals↗