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Biomedical subjects

D Lin

Publications and source records attributed to D Lin.

At least 91 records · Page 5Linked to original sources
PubMed1999

Computed tomographic evaluation of the internal structure of the lateral sacral mass in the upper sacra.

Because dimensions of the upper sacral cortexes vary greatly among individuals, preoperative computed tomographic (CT) evaluation of individual sacrum may help surgeons choose sacral screw insertion techniques. Axial CT scans were performed on 40 dry sacrum specimens to quantitatively evaluate the internal structure of the lateral sacral mass in the first and second segments. The results showed that the greatest cortical thickness in the S1 vertebra was found in the anterior cortex (3.4+/-0.9 mm), followed by the anterolateral (3.2+/-1.2 mm), and anteromedial (2.9+/-1 mm). The greatest cortical thickness in the S2 region was noted in the anteromedial cortex (2.4+/-0.5 mm), followed by the anterior and anterolateral (2.2+/-0.9 mm). The mean percentage of the anterior cortex thickness versus the lateral sacral mass depth was 12.8+/-3.7 for S1 and 11.1+/-2.8 for S2. Bicortical screw placement is recommended to achieve stronger fixation, but care should be taken not to violate the vital structures anterior to the sacrum.

Aged↗
PubMed1999

Evaluation of the upper sacrum by three-dimensional computed tomography.

Axial and sagittal computed tomographic (CT) scans of 40 sacrum specimens were obtained. The measurements of the upper sacral canal and S1-2 and S2-3 anterior sacral foramina were performed on axial scans, and the evaluation of the upper sacral pedicle was based on sagittal scans. The results showed that there were statistically significant differences between male and female specimens in 3 of 29 measurements. In general, the measurements of male specimens were slightly larger than those of the female specimens, and the linear dimensions of the sacral canal, anterior foramina, and pedicle decreased from the S1 to S3. This study indicated that the critical area of the sacral pedicle for screw insertion lies in the junction between the pedicle and vertebral body. CT scans provide more accurate information about the essential sacral anatomy.

Female↗
PubMed1999

[Clinico-pathologic characteristics of malignant thymoma].

OBJECTIVE: To assess the histopathology, clinical staging and treatment of malignant thymoma in relation to prognosis. METHODS: Sixty four cases with malignant epithelial thymic tumors treated in the period of 1958-1995 were retrospectively studied. Archived specimens were categorized according to Levine and Rosai into type I malignant thymoma(MT) and type II thymic carcinoma (TC). MT was histologically classified according to Müller-Hermelink(M-H). Clinical staging was ascertained according to Masaoka's criteria. RESULTS: There were 41 cases of MT and 23 cases of TC. No medullary or mixed thymoma was observed in this series of MT. The 5-year survival rate of patients with MT of predominantly cortical, cortical, and well-differentiated thymic carcinoma (MDTC) subtypes was 75.3%, 44.7% and 43.3%, respectively. That of patients with TC of squamous-cell carcinoma and lympho-epithelioid subtypes was 27.5% and 60.0%, respectively. The 10-year survival rate of these 5 subtypes was 25.3%, 10.0%, 0, 0, 20.0%, respectively(P < 0.05). The 5-year and 10-year survival rates decreased with increase in staging. In 22 patients in stage III and IV who received thoracotomy with biopsy only, their survival rate was significantly lower than that in patients with their tumor resected. CONCLUSION: Histomorphology of the tumor, heterogeneity in cell types, clinical staging and the extent of tumor resection are factors affecting survival.

Adolescent↗
PubMed1999

[The role of mediastinoscopy for the diagnosis of mediastinal tuberculous lymphadenopathy and sarcoidosis].

OBJECTIVE: To find a effective method for diagnosing tuberculous lymphadenopathy and sarcoidosis of mediastinum. METHODS: Mediastinoscopy was conducted in patients who had enlarged mediastinal lymph nodes on chest CT or MRI and were clinically suspected of either tuberculosis or sarcoidosis. Biopsy was done to obtain pathological diagnosis, and make therapeutic program. RESULTS: Of this series of 25 patients, 16 cases were pathologically diagnosed as tuberculous lymphadenopathy, representing 64% (hyperplastic tuberculosis 14 cases; caseous tuberculosis 2 cases); 8 cases were sarcoidosis, representing 32%; one case was difficult to tell tuberculosis from sarcoidosis microscopically, representing 4%. Tuberculosis and sarcoidosis were causes of benign enlargement of mediastinal lymph nodes. They were hard to be differentiated from roentgnologically, sometimes even microscopically; and they might be confused with other malignant diseases, which can also cause the enlargement of mediastinal lymph nodes, such as lymphoma, metastatic malignancies, etc. Thus they were easily resulted in misdiagnosis. Of this series, the initial diagnosis of 21 cases were malignancies, representing 84%, two cases has even undergone chemotherapy at local hospitals. CONCLUSIONS: For patients with enlargement of mediastinal lymph nodes, mediastinoscopy is of great value. It was emphasized to make every effort to obtain definite pathological diagnosis before standard treatment.

Adolescent↗
PubMed1999

[A study of anterior segment structures in primary infantile glaucoma eyes by ultrasound biomicroscopy].

OBJECTIVE: To investigate anterior segment structures in primary infantile glaucoma (PIG) eyes by ultrasound biomicroscopy (UBM) in vivo. METHODS: UBM high frequency transducer (50 mHz) was used to measure and observe the anterior segment of 38 PIG cases (58 eyes). RESULTS: No matter the severity of the disease or the age at onset, the most significant characteristics of the diseased eyes are relative positional changes between scleral spur and angle apex. In three forth of the eyes, the scleral spur lay in the lateral or posterior-lateral site of the angle apex and in one forth of the eyes the site of the tip of scleral spur was parallel with the iris root insertion. The thickness and length of ciliary processes in the eyes of PIG were greater than that of the normal infantile eyes. The ciliary processes were anteriorly displaced, pulled towards the lens, and part of them got into contact with the iris. CONCLUSIONS: The relative positional changes between scleral spur and angle apex in diseased eyes indicate that the poor development of scleral spur and the iris anterior insertion are the basic pathogenesis in PIG.

Anterior Eye Segment↗
PubMed1999

[Expression of P53 protein in premalignant lesion and carcinoma of larynx].

To investigate the expression of P53 protein in the premalignant lesion and carcinoma of laryngeal epithelium, the authors used DO-7, an antibody to wild and mutant type P53 protein. Eleven cases of simple hyperplasia of epithelium (SHE), 32 cases of atypical hyperplasia of epithelium (AHE) and 42 cases of laryngeal squamous cell carcinoma (LSCC) were examined by ABC technique. The results showed that the overexpression of P53 protein were 0%, 31.25% and 52.38% in SHE, AHE and LSCC, respectively. The positive rate of P53 protein were 0%, 33.33% and 75.00% in mild, moderate and severe AHE, respectively. In well, moderately and poorly differentiated carcinomas of larynx, the positive rates were 62.50%, 76.92% and 15.39%, respectively. There were highly significant differences (P < 0.01). No correlation was found between the P53 protein overexpression and the clinical stages, neck lymph node metastasis, local recurrence and, survival of LSCC. The results suggest that the overexpression of P53 protein may play a role in the pathogenesis and development of LSCC.

Carcinoma, Squamous Cell↗
PubMed1999

[Study on family aggregation of cases of advanced schistosomiasis japonica].

AIM: To explore the family aggregation of advanced schistosomiasis japonica. METHODS: Eighty-one cases of advanced schistosomiasis(AS) and 67 cases of non-advanced schistosomiasis with history of infections in Yushan County, Jiangxi Province were chosen as proband groups and control groups respectively, then grades 1 and 2 relatives of them were investigated on AS. Family aggregation of AS was analyzed through comparing the prevalence rate between the close and distant relatives of probands and controls and fitting the observed distribution of AS cases among the population by zero-truncated Poisson distribution and zero-truncated negative binomial distribution. RESULTS: The prevalence rate was higher in the close relatives (Group I relatives) of the probands than in the distant relatives(Group II relatives) of the probands and in the controls' relatives. The observed distribution of AS was beyond the probability of the zero-truncated Poisson distribution, but consistent with the zero-truncated negative binomial distribution. CONCLUSION: Family aggregation of advanced schistosomiasis does exist.

Adult↗
PubMed1999

Pilot study of schistosomiasis control in Poyang lake region.

AIM: To perform a longitudinal survey of the control of schistosomiasis in Fanhu Village hyperendemic for schistosomiasis, Poyang Lake region of Jiangxi Province from 1992 to 1996. METHODS: Annual mass chemotherapy and health education were implemented in all investigated individuals, in 1996, artesunate was used in high risk population in transmission season as a prophylactic measure. RESULTS: The prevalence of S. japonicum infection reduced from 26.0% in 1992 to 10.7% in 1994, the intensity of infection (geometric mean of EPG of feces) in residents decreased from 1.92 in 1992 to 0.55 in 1994, and the morbidity indicators such as hepatomegaly and splenomegaly in the cases also have been improved significantly after chemotherapy. In 1995, both the infection rate and intensity of infection of schistosomiasis were recurred from 10.7% and 0.55 in 1994 to 18.4% and 1.04 respectively due to the floods. In 1996, the infection rate reduced to 5.0% and the intensity of infection also decreased to 0.25 due to the additional measure. CONCLUSION: A mass chemotherapy in conjunction with health education and oral artesunate for preventing reinfection in transmission season is effective for the control of schistosomiasis in lake regions.

Adolescent↗
PubMed1998

Statistical issues for HIV surrogate endpoints: point/counterpoint. An NIAID workshop.

This paper summarizes the proceedings of an NIAID-sponsored workshop on statistical issues for HIV surrogate endpoints. The workshop brought together statisticians and clinicians in an attempt to shed light on some unresolved issues in the use of HIV laboratory markers (such as HIV RNA and CD4+ cell counts) in the design and analysis of clinical studies and in patient management. Utilizing a debate format, the workshop explored a series of specific questions dealing with the relationship between markers and clinical endpoints, and the choice of endpoints and methods of analysis in clinical studies. This paper provides the position statements from the two debaters on each issue. Consensus conclusions, based on the presentations and discussion, are outlined. While not providing final answers, we hope that these discussions have helped clarify a number of issues, and will stimulate further consideration of some of the highlighted problems. These issues will be critical in the proper assessment and use of future therapies for HIV disease.

Biomarkers↗
PubMed1998

Protein Data Bank (PDB): database of three-dimensional structural information of biological macromolecules.

The Protein Data Bank (PDB) at Brookhaven National Laboratory, is a database containing experimentally determined three-dimensional structures of proteins, nucleic acids and other biological macromolecules, with approximately 8000 entries. Data are easily submitted via PDB's WWW-based tool AutoDep, in either mmCIF or PDB format, and are most conveniently examined via PDB's WWW-based tool 3DB Browser.

Database Management Systems↗
PubMed1998

Crystal structure of a human low molecular weight phosphotyrosyl phosphatase. Implications for substrate specificity.

The low molecular weight phosphotyrosine phosphatases (PTPases) constitute a distinctive class of phosphotyrosine phosphatases that is widely distributed among vertebrate and invertebrate organisms. In vertebrates, two isoenzymes of these low molecular weight PTPases are commonly expressed. The two human isoenzymes, HCPTPA and HCPTPB, differ in an alternatively spliced sequence (residues 40-73) referred to as the variable loop, resulting in isoenzymes that have different substrate specificities and inhibitor/activator responses. We present here the x-ray crystallographic structure of a human low molecular weight PTPase solved by molecular replacement to 2.2 A. The structure of human low molecular weight PTPase is compared with a structure representing the other isoenzyme in this PTPase class, in each case with a sulfonate inhibitor bound to the active site. Possible aromatic residue interactions with the phosphotyrosine substrate are proposed from an examination of the binding site of the inhibitors. Differences are observed in the variable loop region, which forms one wall and the floor of a long crevice leading from the active-site loop. A set of residues lying along this crevice (amino acids 49, 50, and 53) is suggested to be responsible for differences in substrate specificity in these two enzymes.

Alternative Splicing↗
PubMed1998

Mutagenesis associated with nitric oxide production in macrophages.

To better understand the mechanisms through which persistent infections/inflammation increase cancer risks, we assessed the potential genotoxic properties of NO produced by macrophages. We recently showed that mouse macrophage RAW264.7 cells were capable of resuming exponential growth after stimulation for NO production by interferon-gamma (IFN-gamma) and/or lipopolysaccharide. Here, we report that increases in mutant fraction (MF) in the endogenous, X-linked, hprt gene of the cells are associated with NO exposure. Cells stimulated with 100 units/ml IFN-gamma continuously for 14 and 23 days produced a total of 9.8 and 14 micromol of NO per 10(7) cells, respectively. MFs in the hprt gene of NO-producing cells were 16.6 and 31.3 x 10(-5), respectively, compared with 2.2 and 2.5 x 10(-5) in untreated cells. Addition of an NO synthase inhibitor, N-monomethyl-L-arginine, to the culture medium decreased NO production and MF by 90% and 85%, respectively. Reverse transcription-PCR and DNA sequencing revealed that NO-associated hprt mutations did not differ significantly from those arising spontaneously, with the exception that certain small deletions/insertions and multiple exon deletions were observed only in the former. MF also increased significantly in cells stimulated for only 4 days with lipopolysaccharide plus IFN-gamma for higher rates of NO production. The types and proportion of hprt mutations induced under these conditions were strikingly similar to those associated with long-term NO exposure. These results indicate that NO exposure results in gene mutations in RAW264.7 cells through mechanisms yet to be identified and may also contribute to spontaneous mutagenesis.

Animals↗
PubMed1998

Electrical cardioversion of atrial fibrillation or flutter with conscious sedation in the age of cost containment.

BACKGROUND: The purpose of this study was to compare the safety, efficacy, and cost of conscious sedation administered by electrophysiologists certified in the use of conscious sedation with sedation administered by anesthesiologists during cardioversion of atrial fibrillation or atrial flutter to sinus rhythm. METHODS AND RESULTS: Patients with hemodynamically stable persistent atrial fibrillation and flutter were included in this study. Group 1 patients (n = 33) were sedated by an anesthesiologist and group 2 patients (n = 26) were sedated by an electrophysiologist. Anesthesiologists used propofol and electrophysiologists used midazolam and morphine for sedation. A cost analysis based on professional charges and cost of medications was performed for both groups and compared. Hospital charges were similar for both groups and were excluded from the cost analysis. Although time to sedation in group 1 was shorter than that in group 2, sedation was adequate in both groups such that no patient in group 1 and only 1 patient in group 2 recalled being shocked. There were no complications in either group. The cost incurred in group 2 was less than that in group 1. CONCLUSIONS: Sedation administered by electrophysiologists for cardioversion of atrial arrhythmias is safe and cost effective. Midazolam and morphine, the sedative agents administered by electrophysiologists, were effective and well tolerated by patients.

Aged↗
PubMed1998

Immunologic response to tetanus toxoid in the elderly: one-year follow-up.

STUDY OBJECTIVE: To determine whether elderly patients documented to have nonprotective titers of anti-tetanus antibodies (ATA) are able to achieve and maintain protective ATA titers for at least 1 year after tetanus immunization. METHODS: Thirty-five outpatients aged 65 or older with documented inadequate ATA titers were given 1 tetanus immunization. Repeat titers were obtained 2 months and 12 months after immunization. Titers were measured with an enzyme-linked immunoassay kit (Bindazyme kit). ATA titers in excess of .17 IU were considered protective. The study was conducted at a large urban geriatric center. RESULTS: The mean age of participants was 78.7 years; 86% (24/28) were women. Repeat ATA titers were obtained an average of 122 days and 493 days after immunization. The mean preimmunization ATA titer was .1 IU, (range .04 to .16 IU). After immunization, the 2-month ATA titer rose a mean of .61 (95% confidence interval [CI] .35 to .87) IU, with 86% (30/35) achieving protective titers. After 1 year only 28 of 35 patients were available for follow-up. Protective titers had been present in all 7 patients lost to follow-up. After 1 year, 82% (23/28) patients had protective titers. The mean ATA titer for the 28 patients was .54 (95% CI -.78 to 1.86) IU, a significant increase from preimmunization levels (P=.002). However, ATA titers changed -.18 (95% CI -.98 to .62) IU between 2 months and 1 year (P=.02). There was no correlation between gender, country of birth, and medical history with development or maintenance of protective titers. CONCLUSION: Administration of 1 tetanus toxoid affords protective immunization to a large portion of the elderly population after 1 year.

Aged↗
PubMed1998

Mutations in the human sterol delta7-reductase gene at 11q12-13 cause Smith-Lemli-Opitz syndrome.

The Smith-Lemli-Opitz syndrome (SLOS; also known as "RSH syndrome" [MIM 270400]) is an autosomal recessive multiple malformation syndrome due to a defect in cholesterol biosynthesis. Children with SLOS have elevated serum 7-dehydrocholesterol (7-DHC) levels and typically have low serum cholesterol levels. On the basis of this biochemical abnormality, it has been proposed that mutations in the human sterol Delta7-reductase (7-DHC reductase; E.C.1.3.1.21) gene cause SLOS. However, one could also propose a defect in a gene that encodes a protein necessary for either the expression or normal function of sterol Delta7-reductase. We cloned cDNA encoding a human sterol Delta7-reductase (DHCR7) on the basis of its homology with the sterol Delta7-reductase from Arabidopsis thaliana, and we confirmed the enzymatic function of the human gene product by expression in SLOS fibroblasts. SLOS fibroblasts transfected with human sterol Delta7-reductase cDNA showed a significant reduction in 7-DHC levels, compared with those in SLOS fibroblasts transfected with the vector alone. Using radiation-hybrid mapping, we show that the DHCR7 gene is encoded at chromosome 11q12-13. To establish that defects in this gene cause SLOS, we sequenced cDNA clones from SLOS patients. In three unrelated patients we have identified four different mutant alleles. Our results demonstrate both that the cDNA that we have identified encodes the human sterol Delta7-reductase and that mutations in DHCR7 are responsible for at least some cases of SLOS.

Alleles↗
PubMed1998

[Glutathione S-transferase M1, T1 genotypes and the risk of esophageal cancer: a case-control study].

To examine the association between genetic polymorphisms of glutathione S-transferase (GST) M1 and T1 and susceptibility to esophageal cancer, a multiplex polymerase chain reaction method was used to detect the presence or absence of the GSTM1 and GSTT1 genes in genomic DNA isolated from surgically removed esophageal tissues or scraped esophageal cells from cases with cancer (n = 45), cases with severe hyperplasia (n = 45), and sex/age matched normal controls (n = 45) from a high risk area, Linxian, China. Results showed that the frequency of the GSTM1-null genotype in cancer cases (44.4%) or hyperplasia cases (44.4%) was not significantly different from that in controls (46.7%). Similarly, no statistically significant differences were observed in the frequency of GSTT1-null genotype in cancer cases (40.0%) or hyperplasia cases (37.8%) when compared with the controlled population (51.1%). However, the frequency of combined GSTM1-nonnull and GSTT1-nonnull genotypes in cases with cancer (40.0%) and cases with hyperplasia (37.8%) showed a significant increase compared to that in controls (22.2%). Persons with both GSTM1 and GSTT1 positive genotypes had 4-fold risk in developing esophageal cancer (odds ratio, OR = 4.20; 95% confidence interval, CI = 1.23-14.36) and 2.6-fold risk for hyperplasia (OR = 2.64; 95% CI = 0.84-8.30), respectively. These results suggest that combined GSTM1-nonnull and GSTT1-nonnull genotypes may act as risk factor in the development of esophageal cancer in Linxian population.

Adult↗
PubMed1998

[Chemoprotection by green tea against the formation of food-borne carcinogen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP)-DNA adducts in rats].

OBJECTIVE: The food-borne mutagen 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) induces colon and mammary gland tumors in rats and has been implicated in the etiology of human cancer, particularly colorectal cancer. This study was conducted to examine the potential chemopreventive effect of Chinese green tea against PhIP-DNA adduct formation in rats and its possible mechanisms. METHODS: Sprague-Dawley rats were maintained on freshly prepared aqueous extract of Chinese green tea (3%) or tap water as the sole source of drinking fluid for 10 days prior to administration with a single dose of PhIP (10 mg/kg body wt) by oral gavage. Rats were sacrificed at 20 h after PhIP treatment and PhIP-DNA adducts in the colon, heart, lung, and liver were analyzed using 32P-postlabeling technique. The activity of cytosolic glutathione S-transferases (GSTs) in the liver, lung and colon mucosa was also determined using CDNB as substrate. RESULTS: The levels of PhIP-DNA adducts in the four tissues of rats treated with PhIP alone were highest in the colon (53 +/- 9 adducts/10(8) nucleotides), followed by heart (41 +/- 14 adducts/10(8) nucleotides) and lung (22 +/- 5 adducts/10(8) nucleotides), but much lower in the liver (5 +/- 3 adducts/10(8) nucleotides). Rats pre-treated with green tea had significantly reduced levels of PhIP-DNA adducts, with the inhibition rates being 59%-80%, respectively. While the organ distribution profile of the adducts was not altered by tea treatment as compared with controls given PhIP alone. The GST activity towards CDNB in hepatic, colonic and lung cytosols appear not to be modified by drinking green tea. CONCLUSION: These results support a protective role for green tea against PhIP-initiated carcinogenesis in rats and suggest that consumption of green tea may have significant impact in chemoprevontion against human cancer presumably related to PhIP and other heterocyclie amines.

Animals↗