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Biomedical subjects

S C Lin

Publications and source records attributed to S C Lin.

At least 19 recordsLinked to original sources
PubMed1992

Morphologic characterization and quantitative assessment of mitral regurgitation with ruptured chordae tendineae by transesophageal echocardiography.

To compare the accuracy of transesophageal echocardiography (TEE) with that of transthoracic echocardiography (TTE) in the detection of morphologic characteristics and in the quantitative assessment of the severity of mitral regurgitation with ruptured chordae tendineae, 40 patients with ruptured chordae tendineae (group 1) and 20 patients with moderate or severe mitral regurgitation due to other causes (group 2) were studied. All echocardiograms were recorded before cardiac surgery. Cardiac catheterization was performed in 55 patients (92%). TEE showed greater sensitivity and negative predictive value than TTE (100 vs 65%, and 100 vs 56%, respectively; p < 0.005) in the diagnosis of ruptured chordae tendineae. Visualization of the ruptured chordae (termed snake-tongue sign) was highly sensitive and specific (93 and 95%, respectively) for establishing the diagnosis of ruptured chordae tendineae. The severity of mitral regurgitation in group 1 patients evaluated by TTE color flow mapping was underestimated by 2 grades in 1 patient and by 1 grade in 6 patients, and overestimated by 1 grade in 1 patient, compared with left ventriculography. In contrast, by TEE color flow mapping it was underestimated by 1 grade in 1 and overestimated by 1 grade in 1 patient. TEE color flow mapping showed better correlation with angiography than did TTE color flow mapping (r = 0.82 vs r = 0.49).

Adult↗
PubMed1992

Reappraisal by transesophageal echocardiography of the significance of left atrial thrombi in the prediction of systemic arterial embolization in rheumatic mitral valve disease.

Systemic arterial embolization imparts a significant risk of serious complications throughout the lives of patients with rheumatic heart disease. Left atrial (LA) thrombi have been thought to be the major source of emboli. A transesophageal echocardiography (TEE) study of 260 consecutive patients with rheumatic mitral valve disease was performed during a period of 24 months, with particular reference to understanding the association between LA thrombi and embolic complications. Of these patients, 155 had predominant mitral stenosis, 24 had significant mitral regurgitation, and the remaining 81 with xenograft mitral valve replacement developed valvular dysfunction (25 resulted in predominant mitral stenosis and 56 in significant mitral regurgitation). LA thrombi were detected in 38 patients (group A) and absent in 222 (group B). Group A patients had a higher frequency of recent (less than or equal to 1 week before TEE study) and remote (greater than 1 week before) embolization than did group B patients (recent: 26.3 vs 5.4% [p less than 0.001]; remote: 18.4 vs 5.0% [p less than 0.01]). The frequency of atrial fibrillation was also greater in group A patients (100 vs 74.3%; p less than 0.001). The exclusion of patients with significant mitral regurgitation and sinus rhythm had no effect on the association between LA thrombi and evidence of previous embolization. It is concluded that TEE is a convenient diagnostic modality that can be used to identify a subset of patients with rheumatic mitral valve disease at high risk for systemic embolization. Consequently, preventive anticoagulation for possible embolic complications should be more vigorously adhered to in patients with rheumatic mitral valve disease and LA thrombi.

Echocardiography↗
PubMed1992

Prospective study of blood culture during transesophageal echocardiography.

To ascertain the incidence and significance of bacteremia associated with transesophageal echocardiography (TEE), 132 consecutive patients (aged 17 to 73 years) free of apparent infection who were undergoing 135 transesophageal echocardiographic procedures from October 1990 to August 1991, were prospectively studied. For each procedure, two sets of blood cultures were obtained for culture 30 to 60 minutes before TEE, immediately after, and 180 to 240 minutes after the procedure. For each blood culture, 10 ml of venous blood was evenly inoculated into aerobic and anaerobic culture bottles and inoculated for 7 days using a radiometric system. A throat swab was obtained immediately before each procedure. Three of 270 preprocedure blood cultures were positive for Bacillus cereus, Staphylococcus simulans, and Peptostreptococcus species, respectively. No blood culture was positive in the immediate postprocedure period. Two of 270 late blood samples grew Staphylococcus epidermidis in the same patient. Nevertheless, the microorganisms isolated from blood cultures were different from those isolated from the throat swab. No patients had fever or evidence of infective endocarditis after TEE during the follow-up period. It is concluded that the incidence of TEE-related bacteremia is extremely low, and a general recommendation for antibiotic prophylaxis during TEE is not warranted.

Adolescent↗
PubMed1992

Presence of anti-basal cell antibodies in oral lichen planus.

BACKGROUND: An autoimmune hypothesis for oral lichen planus (OLP) has been proposed, but no anti-basal cell antibodies (anti-BCA) have been found in the sera of patients with OLP. OBJECTIVE: Our purpose was to test whether the negative results of anti-BCA assays in sera have been due to the insensitivity of the substrates. Rat esophagus, monkey esophagus, as well as human oral mucosa and skin were used to detect anti-BCA in sera of OLP patients. METHODS: By indirect immunofluorescence technique, the rat esophagus was found to be the most sensitive substrate. Therefore it was used as the only substrate to test the presence of anti-epithelial cell antibodies (anti-ECA) in a large group of patients with OLP and other oral mucosal diseases or normal control subjects. RESULTS: The results showed that anti-ECA were detected in 54% (34 of 63) of patients with OLP, 71% (15 of 21) of patients with aphthous ulcers, 29% (6 of 21) of patients with oral carcinoma, 20% (2 of 10) of patients with traumatic ulcer, and 7% (1 of 15) of patients with periodontitis but none of the healthy control subjects (n = 41). The presence of anti-BCA in OLP patients' sera was persistent and lasted for a few months or years. There was a decrease in the serum anti-BCA titers in six of eight anti-BCA-positive OLP patients after topical application of triamcinolone. CONCLUSION: These anti-BCA that persist longer in OLP patients' sera may be autoantibodies that are raised against altered basal cell-specific antigens.

Adult↗
PubMed1992

Surface-active compounds from microorganisms.

Microbial surfactants are a structurally diverse group of compounds consisting of hydrophilic and hydrophobic domains and which partition preferentially at interfaces. Biosurfactants are of increasing interest commercially as substitutes for synthetic surfactants particularly for environmental applications. This article discusses recent progress in the genetic and biochemical analysis of biosurfactant synthesis as well as the current status of fermentation technologies.

Bacteria↗
PubMed1992

Effects of glucocorticoids on expression of the fos protooncogene in AtT-20 cells.

Glucocorticoid regulation of expression of the protooncogene fos has been examined in AtT-20 cells at both the RNA and protein levels. When cells were incubated continuously in the presence of dexamethasone, an early (30 min) rise in the expression of fos mRNA was observed, which declined by 1 h, but rose again after 2 h of hormone treatment. Six hours after hormone treatment, fos mRNA levels had returned to control levels in spite of the continued presence of dexamethasone. Serum treatment resulted in a sustained increase in fos mRNA levels; however, the glucocorticoid and serum effects were additive. Dexamethasone and/or serum both increased the steady state levels of fos protein. Glucocorticoid treatment of AtT-20 cells results in complex changes in fos expression, but does not affect their viability or growth rate; these results suggest that fos may play a role in mediation or modulation of glucocorticoid effects other than growth.

Animals↗
PubMed1991

Cloning and characterization of a testis-specific thymosin beta 10 cDNA. Expression in post-meiotic male germ cells.

Thymosin beta 10 is one of a small family of proteins closely related in sequence to thymosin beta 4, recently identified as an actin-sequestering protein. A single molecular weight species of thymosin beta 10 mRNA is present in a number of rat tissues. In adult rat testis, an additional thymosin beta 10 mRNA of higher molecular weight was identified. Nucleotide sequencing of cDNA clones complementary to the testis-specific thymosin mRNA indicated that this mRNA differed from the ubiquitous thymosin beta 10 mRNA only in its 5'-untranslated region, beginning 14 nucleotides upstream of the translation initiation codon. These results, together with primer extension experiments, suggest that the two thymosin beta 10 mRNAs are transcribed from the same gene through a combination of differential promoter utilization and alternative splicing. The novel thymosin beta 10 mRNA could be detected only in RNA isolated from sexually mature rat testis. Both mRNAs were present in pachytene spermatocytes; only the testis-specific mRNA was detected in postmeiotic haploid spermatids. Immunoblot analysis using specific antibodies showed that the thymosin beta 10 protein synthesized in adult testis was identical in size to that synthesized in brain. Immunohistochemical analysis showed that the protein was present in differentiating spermatids, suggesting that the testis-specific thymosin beta 10 mRNA is translated in haploid male germ cells.

Amino Acid Sequence↗
PubMed1990

Rapid high-performance liquid chromatography of nucleic acids with polystyrene-based micropellicular anion exchangers.

Nucleic acids were separated by ion-exchange chromatography on 30 x 4.6 and 100 x 4.6 mm columns packed with a micropellicular anion exchanger made of 3-microns rigid polystyrene-based non-porous microspheres with a covalently bound hydrophilic layer and DEAE functional groups at the surface. The stationary phase particles showed negligible swelling in methanol according to permeability measurements with water and methanol. Nucleic acids and their fragments including synthetic single-stranded oligonucleotides, linear, nicked and supercoiled DNAs as well as DNA restriction fragments were separated in less than 5 min, a time scale that is much smaller than that of conventional high-performance liquid chromatographic analysis for such samples. When only buffer and sodium chloride were used in the eluent for the separation of double-stranded DNA restriction fragments pGEM-3Z/Taq I, electrophoretic analysis of the effluent revealed the presence of smaller fragments in the bands of the larger ones. Upon addition of ethylenediaminetetraacetic (EDTA) salt to the eluent, however, such contamination by shorter fragments was no longer observed. In the absence of EDTA, magnesium chloride in the eluent at a concentration of 1 mM precluded the separation of the restriction fragments under otherwise identical chromatographic conditions.

Anion Exchange Resins↗
PubMed1990

Developmental expression of mRNAs encoding thymosins beta 4 and beta 10 in rat brain and other tissues.

In the course of screening a fetal rat cerebellum cDNA library for developmentally regulated sequences, we have identified a cDNA clone identical in sequence to that encoding a protein originally isolated from thymus, thymosin beta 10. Based on northern hybridization analyses with gene-specific oligonucleotide probes derived from the 3'-untranslated regions of thymosin beta 10 mRNA and the closely related beta 4 mRNA, we showed that both thymosin mRNAs were present at highest levels in fetal cortex and cerebellum but also were present at varying levels in all other fetal tissues examined (thymus, spleen, lung, kidney, adrenal, heart, and liver). Steady-state levels of thymosin beta 10 mRNA in cerebellum declined to negligible levels after day 14 of postnatal development. Its levels exhibited a similar pattern in developing cortex, although the adult cortex had slightly higher thymosin beta 10 mRNA levels. These results suggest that thymosin beta 10 mRNA is subject to strong developmental regulation in the rat central nervous system. Reduction of thymosin beta 10 mRNA levels also was seen during development of kidney, heart, and liver. Levels of both thymosin beta 10 and beta 4 mRNAs remained relatively constant during development of thymus, spleen, and lung. Thymosin beta 4 mRNA levels dropped much less sharply during brain development than did levels of the beta 10 mRNA. Testis and ovary contained the highest relative levels of thymosin beta 10 mRNA among adult tissues, but little thymosin beta 4 mRNA. A novel thymosin beta 10 mRNA species unique to adult testis was detected. These results indicate that both thymosins must function in the development of brain and many other organs, as well as in different subsets of organs in the adult.

Animals↗
PubMed1990

Sleep disorders in psychiatric practice.

Sleep disorders medicine and psychiatry interface in numerous ways. Most psychiatric patients have a complaint about sleep, and regardless of the theoretical orientation of a psychiatrist, understanding of a patient's sleep function is an important part of assessment. The success or failure of treatment will be strongly influenced by the effect of that treatment on the patient's sleep disorder. The psychiatrist can provide expertise in treating patients with primary sleep disorders, offering pharmacologic consultations, and recommending psychotherapy or behavioral management. Conversely, a knowledge of primary sleep disorders should make the psychiatrist a more effective practitioner.

Humans↗
PubMed1990

Narcolepsy update.

Narcolepsy, a disorder of excessive daytime sleepiness that affects more than 125,000 people in the United States, is technically defined as a daytime mean sleep latency (time elapsed before falling asleep) of less than 5 minutes in conjunction with verification of rapid eye movement sleep in at least two of five daytime nap periods. Cataplexy, hypnagogic hallucinations, and sleep paralysis are frequently associated with narcolepsy. Currently, overnight polysomnography and multiple sleep latency testing in a sleep disorders laboratory are used to diagnose narcolepsy. Standard pharmacologic therapy consists of the judicious use of stimulants to improve alertness and the administration of tricyclic and other antidepressant drugs to suppress cataplexy. In addition, good sleep hygiene (a regular sleep-wake schedule, an adequate amount of sleep at night, and scheduled daytime naps) is essential for optimal management of this disorder. Patient and family education about narcolepsy and its treatment is also important. Even with use of the best available treatment regimens, many patients with narcolepsy have substantial vocational and social impairments.

Animals↗
PubMed1990

HLA-DR and DQ antigens in Chinese patients with oral lichen planus.

A study of HLA-DR and DQ typing in 44 patients with oral lichen planus (OLP) (28 women and 16 men) and in 107 normal controls of both sexes was performed by using Terasaki's oriental tray. Twenty-eight patients had erosive forms of lichen planus (OLPe). Serologic typing revealed a highly significant increase of HLA-DR 9 and Te 22 antigens in the patient group. Considering our findings and those in other autoimmune diseases, it is hypothesized that OLP is a localized autoimmune disease and the HLA-DR9 in Chinese takes the place of HLA-DR3 in Caucasians in carrying the genes which predispose to the development of autoimmune disease.

Epitopes↗
PubMed1990

Staphylococcus aureus endocarditis in drug addicts: report of 2 cases.

Two young men presented with prolonged hectic fever and chills followed by chest pain, dyspnea and hemoptysis. The chest films revealed multiple lung infiltrates, and blood cultures yielded Staphylococcus aureus. Echocardiographic examination confirmed the diagnosis of tricuspid valve endocarditis. Multiple punctate lesions in the bilateral inguinal areas and dragon tattoos over the forechest gave rise to the suspicion of drug abuse. After prolonged antimicrobial therapy, bacteremia was eliminated, and elective vegetectomy and valvuloplasty were performed on one of the patients. The other one suffered recurrent episodes of pulmonary embolism. Disappearance of the large vegetation was disclosed by echocardiography. Both of them eventually regained their health with the abstinence of drugs. This report illustrates two typical cases of infective endocarditis in drug addicts.

Adult↗
PubMed1990

[Effects of subgingival antimicrobial irrigation in chronic periodontitis--clinical observation].

One week prior to the establishment of baseline records, 144 sites with a probing pocket depth of 5-7 mm in 13 periodontitis patients were treated with plaque control and root planning. Sites with periodontitis involvement in each patient were divided, by split mouth design, into 4 quadrants. Each quadrant was irrigated subgingivally with either 0.05% metronidazole or 0.05% ornidazole, or 0.2% chorhexidine, or 0.9% normal saline (control) once every 2-3 days for 4 weeks. The plaque index, sulcus bleeding index, probable pocket depth and gingival index were assessed at the baseline and at 4 weeks, 8 weeks and 12 weeks following initial preparation. All 4 clinical parameters in the ornidazole treated group showed significant improvement as compared with baseline values, but the improvements were not maintained to the end of the study. Except for improvement in the sulcus bleeding index and the gingival index in the ornidazole group, which was superior to that of the metronidazole group at the 4th week, there were no significant differences in other parameters between the ornidazole, metronidazole and chlorhexidine groups at the irrigation sites. From these data we can tentatively conclude that subgingival irrigation with ornidazole in deep pockets is more effective than metronidazole or chlorhexidine in nonsurgical periodontal therapy.

Adult↗
PubMed1990

Extracorporeal shock wave lithotripsy. Experience in treating 245 patients with gallbladder stones.

An EDAP LT-01 lithotripter was used to treat 245 patients with functioning gallbladders containing one to three radiolucent stones of less than 20 mm in diameter. Ursodeoxycholic acid was administrated as adjuvant litholytic therapy. The gallbladder stones disintegrated in 98.8% of patients and disappeared completely in 21.2% within 1 month after lithotripsy, in 26.5% within 2 months, in 33.9, 40, 46.5, 48.6 and 53.9% within 3, 4, 6, 9, and 12 months, respectively. Adverse effects after lithotripsy were dull abdominal pain (49.4%), biliary colic (13.1%), jaundice (1.2%), and pancreatitis (0.4%). Extracorporeal shock wave lithotripsy combined with litholytic therapy is a non-invasive, painless, safe, and effective treatment in selected patients. Patients with solitary radiolucent stone less than 20 mm in diameter are considered candidates for extracorporeal shock wave lithotripsy (ESWL). The key to success of ESWL lies in the strict selection of patients, careful monitoring throughout the lithotriptic procedure, and enough litholytic therapy. The disadvantages of this method include strict selection of patients and high costs, poor curative effect, and recurrence of stones (11.4% of patients).

Adult↗