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Biomedical subjects

Y M Chen

Publications and source records attributed to Y M Chen.

At least 91 records · Page 5Linked to original sources

A new classification of molar furcation involvement based on the root trunk and horizontal and vertical bone loss.

This study presents a new classification of molar furcation involvement based on the root trunk and horizontal and vertical attachments, and relates them to guidelines in diagnosis, prognosis, and treatment of molar furcation involvements. The type of root trunk were classified on the basis of the ratio of vertical dimension of root trunk to root length as types A, B, and C. Based on the results of this study, the authors conclude that consideration of the root trunk type as well as the horizontal and vertical attachment loss in the classification of molar furcation involvements may facilitate prognosis, diagnosis, and treatment planning.

Alveolar Bone Loss↗

Randomized, double-blind, placebo-controlled study of transdermal nicotine patch for smoking cessation.

Smoking cessation is an arduous process because nicotine withdrawal syndrome, which occurs following sudden interruption of nicotine use in long-term smokers, frequently prevents them from giving up the habit. Nicotine supplement systems may relieve smokers' nicotine withdrawal symptoms and, thus, help in the process of abstinence from smoking. The purpose of the present study was to investigate the effectiveness and safety of a 30-mg transdermal nicotine patch in a smoking cessation program for Chinese smokers. In this randomized, double-blind, placebo-controlled study, 30 heavy smokers, who had smoked more than 20 cigarettes per day for more than a year, were treated with 30-mg transdermal nicotine patches, and 32 heavy smokers were given placebo patches during a 6-week smoking cessation program. The clinical characteristics of the two groups were similar. After 6 weeks, the use of the transdermal nicotine patch was associated with markedly reduced nicotine dependence and severity of withdrawal symptoms. Nineteen (63%, 95% confidence interval, CI, 46%-80%) of the smokers treated with the transdermal nicotine patch had successfully quit smoking at the end of the program (6 weeks) and nine (30%, 95% CI 14%-46%) remained abstinent 1 year later. In contrast, only 11 (34%, 95% CI 18%-50%) of the smokers in the placebo group had successfully stopped smoking after 6 weeks, and three remained abstinent 1 year later (9%, 95% CI 0%-19%). However, there was no statistically significant difference between the two groups of smokers after 1 year of follow-up (p = 0.08). Side-effects were minimal and did not affect the efficacy of the skin patch. The results indicate that the transdermal nicotine patch is an effective aid in smoking cessation programs.

Administration, Cutaneous↗

Expression of a gene encoding a 16.9-kDa heat-shock protein, Oshsp16.9, in Escherichia coli enhances thermotolerance.

A gene encoding the rice 16.9-kDa class I low-molecular-mass (LMM) heat-shock protein (HSP), Oshsp16.9, was introduced into Escherichia coli using the pGEX-2T expression vector to analyze the possible function of this LMM HSP under heat stress. It is known that E. coli does not normally produce class I LMM HSPs. We compared the survivability of E. coli XL1-Blue cells transformed with a recombinant plasmid containing a glutathione S-transferase (GST)-Oshsp16.9 fusion protein (pGST-FL cells) with the control E. coli cells transformed with the pGEX-2T vector (pGST cells) under heat-shock (HS) after isopropyl beta-D-thiogalactopyranoside induction. The pGST-FL cells demonstrated thermotolerance at 47.5 degrees C, a treatment that was lethal to the pGST cells. When the cell lysates from these two E. coli transformants were heated at 55 degrees C, the amount of protein denatured in the pGST-FL cells was 50% less than that of the pGST cells. Similar results as pGST-FL cells were obtained in pGST-N78 cells (cells produced a fusion protein with only the N-terminal 78 aa in the Oshsp16.9 portion) but not in pGST-C108 cells (cells produced a fusion protein with C-terminal 108 aa in the Oshsp16.9 portion). The acquired thermotolerant pGST-FL cells synthesized three types of HSPs, including the 76-, 73-, and 64-kDa proteins according to their abundance at a lethal temperature of 47.5 degrees C. This finding indicates that a plant class I LMM HSP, when effectively expressed in transformed prokaryotic cells that do not normally synthesize this class of LMM HSPs, may directly or indirectly increase thermotolerance.

Cloning, Molecular↗

Frequent detection of aberrant RNA transcripts of the CDKN2 gene in human gastric adenocarcinoma.

The tumor-suppressor gene CDKN2 (p16/INK4A/MTS1) is frequently altered in human gastric-cancer cell lines. However, mutation of the CDKN2 gene in primary human gastric-carcinoma tissues as seen through genomic DNA analysis has rarely been reported. In this study, a method combining reverse transcription and nested polymerase chain reaction was developed to detect different RNA transcripts of the CDKN2 gene in human gastric cancers. The results showed that, besides the wild-type CDKN2 transcript, 5 of 11 (45.5%) diffuse-type and 3 of 10 (30%) intestinal-type primary gastric adenocarcinoma had aberrant CDKN2 RNA transcripts. Among these 8 tumorous specimens with abnormal CDKN2 RNA transcripts, 6 had intragenic deletions of part of both CDKN2 exons 1 and 2, including 1 case which had an additional inserted sequence from part of CDKN2 intron 2. In addition, 1 case had a deletion of part of CDKN2 exon 1 and 1 case had its entire exon 2 deleted. In contrast, matched normal gastric mucosal tissues from the same patients did not have any aberrant CDKN2 RNA transcript. Furthermore, CDKN2 exon 1 or 2 genomic DNA from all the gastric-carcinoma tissues were PCR-amplified and sequenced and no genetic alteration was detected. Therefore, alteration and heterozygous expression of CDKN2 appears to be involved in the pathogenesis of human gastric cancers.

Adenocarcinoma↗

Antibody reactivities to tumor-suppressor protein p53 and HTLV-I Tof, Rex and Tax in HTLV-I-infected people with differing clinical status.

Since the presence of anti-p53 antibody has been correlated with the mutation and accumulation of p53, the aim of this study was to detect anti-p53 antibody and understand its correlations with anti-Tof, -Rex, or -Tax antibody reactivity in HTLV-I infected people differing in their clinical status. A plasmid (pGEX-Tof) was constructed to express Tof recombinant protein (RP) in Escherichia coli. Serum samples from 50 asymptomatic carriers (ACs), 50 adult T-cell leukemia (ATL) and 50 HTLV-I-associated myelopathyltropical spastic paraparesis (HAM/TSP) patients were assayed for reactivity with different RPs by Western immunoblotting. The results showed that 2% of ACs, 4% of ATL patients and 6% of HAM/TSP patients had anti-p53 antibody. Therefore, anti-p53 antibody is not a useful serological marker for clinical management of HTLV-I infected people. Only 1 HAM/TSP patient had anti-Tof antibody whose specificity was further confirmed by antibody competition enzyme immunoassay. This study demonstrates that Tof protein is immunogenic in vivo, suggesting that it plays a role in the life cycle and pathogenesis of HTLV-I. The rate of anti-Rex antibody among HAM/TSP patients was significantly higher than that of ACs or ATL patients. In addition, 50% of ACs, 42% of ATL and 98% of HAM/TSP patients had anti-Tax antibody. McNemar's test showed that the presence of anti-p53 antibody did not have any correlation with the anti-Tax antibody in HTLV-I-infected people, while the correlation between anti-p53 and anti-Rex antibodies or anti-p53 and anti-Tof antibodies cannot be ruled out in this study.

Animals↗

Leptospirosis: an ignored cause of acute renal failure in Taiwan.

Leptospirosis, caused by a spirochete, is the most common zoonosis in domestic or wild animals. Animals excrete infected urine in soil or water and may cause human infections through abrased wound, mucosa, conjunctiva, or by swallowing contaminated water. Clinical presentations of leptospirosis are mostly subclinical. Five to ten percent of leptospirosis are fatal, causing fever, hemorrhage, jaundice, and acute renal failure (Weil's syndrome). Leptospirosis has been ignored as a cause of acute renal failure in Taiwan. We report two patients with leptospirosis who presented with high fever, abdominal pain, jaundice, and acute renal failure. Patient 1 died on day 12 of admission of multiple organ failure associated with pancytopenia, hypogammaglobulinemia, and reactive hemophagocytosis. Leptospirosis was recognized after death. Patient 2 was admitted with similar presentations 2 weeks later. Penicillin and doxycycline were given early in the course, and azotemia, jaundice, respiratory failure, and aseptic meningitis gradually improved. Renal biopsy showed interstitial nephritis. Several tubular clearance tests showed proximal tubular defect with severe bicarbonate wasting (FeHCO3- 20.9%) and incomplete type II renal tubular acidosis without affecting the distal nephron. After 80 days of treatment, this patient was discharged with recovery of conscious level and renal function. This is the first leptospirosis patient with detailed tubular functional and morphological studies of the kidney. Diagnosis of leptospirosis was made by microscopic agglutination test (MAT) for antibody to leptospira and by polymerase chain reaction (PCR) for leptospira DNA in blood and urine (interrogans serogroup australis in case 1 and Leptospira borgpetersenii serogroup ballum in case 2). Because active surveillance has resulted in 13 cases diagnosed as leptospirosis islandwide thereafter, underestimation and ignorance of leptospirosis as a cause of acute renal failure may occur in Taiwan. Therefore, an area with a low leptospirosis incidence may actually have a very high incidence. Leptospirosis should be suspected in febrile patients with jaundice and renal failure when pathogens cannot be identified by traditional culture for microorganisms.

Abdominal Pain↗

Functional activity of sporamin from sweet potato (Ipomoea batatas Lam.): a tuber storage protein with trypsin inhibitory activity.

Sporamin accounts for about 60% to 80% of total soluble protein in sweet potato tubers, and the predicted protein sequence of sporamin shares significant amino acid sequence identity with some Kunitz-type trypsin inhibitors. We constructed three recombinant plasmids with cDNAs that encode preprosporamin, prosporamin, and sporamin, and these three were expressed in Escherichia coli cells as fusion proteins. All three forms of sporamin expressed in E. coli were shown to have strong inhibitory activity to trypsin in vitro, suggesting that post-translational modifications are not essential for trypsin inhibitory activity. Northern blot analysis showed that sporamin transcripts could be systemically induced in leaf tissue of sweet potato by wounding. Therefore, sporamin may have a defense role as a protease inhibitor, in addition to its role as a storage protein.

Amino Acid Sequence↗

Ethanol-induced cell death by lipid peroxidation in PC12 cells.

Free radical generation is hypothesized to be the cause of alcohol-induced tissue injury. Using fluorescent cis-parinaric acid and TBARS, lipid peroxidation was shown to be increased in the presence of trace amounts of free ferrous ion in PC12 cells. This increase in lipid peroxidation was enhanced by ethanol in a dose dependent manner and also correlated with loss of cell viability, as measured by increased release of lactate dehydrogenase (LDH). Resveratrol, a potent antioxidant, had a protective effect against lipid peroxidation and cell death. These findings strongly suggest that ethanol-induced tissue injury and cell death is a free radical mediated process, and may be important in alcohol-related premature aging and other degenerative diseases.

Animals↗

Cross sectional study of use of alternative medicines in Chinese cancer patients.

The aim of this study was to ascertain the prevalence of alternative medicine consumption in Chinese cancer patients on active conventional treatment. A cross sectional survey of 100 consecutive advanced cancer patients admitted to a cancer clinical trial referral unit were personally interviewed by their assigned oncology research nurse using a specially designed questionnaire. The results showed that 64% of our patients used indigenous Chinese medication. In all age groups except the over-70s (P = 0.043), > 50% took such medication, more female (76%) than male (57.6%) patients (P = 0.323). Patients of all educational levels (P = 0.062) and religious backgrounds (P = 0.08) consumed alternative medicines. Duration of alternative medication consumption was less than three months in 50% of patients, with costs between US$40 and 2000/month for 70% of patients. Reasons cited for alternative medication consumption was hope that it might be of some benefit to their well being or disease control, and maybe even result in a miracle cure. Sources of advice on medication were mostly from strangers (by word of mouth), family, friends, the media, and infrequently from qualified professional Chinese doctors. Reasons for discontinuing such treatment were mostly given as lack of positive effect. In conclusion, Chinese cancer patients, willingly, rampantly and non-selectively seek out and consume alternative medications, with almost total ignorance of the medication consumed, oblivious to any potential side effects, and with little subjective benefit.

Adult↗

Mitomycin-C induced hemolytic uremic syndrome: a case report and literature review.

Hemolytic uremic syndrome spontaneously arises in a few patients with advanced cancer, but it is more commonly related to the use of certain chemotherapeutic agents. Mitomycin-C is, etiologically, the most common causative agent inducing hemolytic uremic syndrome, in a dose dependent manner. We report this syndrome, attributable to mitomycin-C at a cumulative dose of 40 mg/m2, in a gastric cancer patient. A 42-year-old female with stage III gastric cancer underwent radical gastrectomy and was given mitomycin-C at 10 mg/m2 intravenously every four weeks as adjuvant therapy. Hemolytic uremic syndrome was diagnosed three months after the last dose of mitomycin-C administration. The most prominent symptoms included pallor, hypertension and anasarca, with laboratory evidence of microangiopathic hemolytic anemia, azotemia and hyperkalemia. Her disease was progressive, but fortunately stabilized after staphylococcus column A dialysis. Her disease remained in remission for 24 months from the time of diagnosis, and then relapsed in the form of peritoneal carcinomatosis with partial intestinal obstruction.

Adenocarcinoma↗

Temporal relationship between cancers of the lung and upper aerodigestive tract.

We retrospectively reviewed the chart records at the Veterans General Hospital-Taipei for the period between January 1985 and December 1994 to examine the temporal relationship between cancers of the lung and upper aerodigestive tract. A total of 56 patients (54 males, 2 females) with histocytologically proven double primary cancers, with either lung cancer or upper aerodigestive tract cancers appearing first, were found. Squamous cell carcinoma was the most frequent histologic type of lung cancer (squamous 57%, adenocarcinoma 27%, poorly differentiated carcinoma 9%, small cell lung cancer 7%). The incidence of lung cancer patients with upper aerodigestive tract cancer was 0.9% (56/6412). There was no significant difference in the occurrence of upper aerodigestive tract cancer between non-small cell and small cell lung cancer (P > 0.05). However, the incidence of squamous cell lung cancer with upper aerodigestive tract cancer was higher than that of non-squamous cell lung cancer (P < 0.05). With regard to the location of lung cancer, the right lung was more commonly affected than the left (P < 0.001). The locations of upper aerodigestive tract cancers in these lung cancer patients were as follows: larynx 24, nasopharynx 11, esophagus 10, hypopharynx 4, pharyngeal tonsils 2, oral cavity 5. Most upper aerodigestive tract cancers were diagnosed before lung cancer (36/56, 64%), and lung cancer was diagnosed within 3 years in more than half of cases after the diagnosis of upper aerodigestive tract cancer (58.3%). Most lung cancers that preceded upper aerodigestive tract cancer were at an early stage at diagnosis (stage I 4, stage Illa 1), whereas the others, appearing either synchronously or after the diagnosis of upper aerodigestive tract cancer, were mostly at the late stage. There was no difference in survival between lung cancer patients with upper aerodigestive tract cancer and those without (P > 0.05).

Adenocarcinoma↗

Phase II study of ifosfamide and etoposide chemotherapy for extensive-disease small-cell lung cancer.

We conducted a phase II study of ifosfamide and etoposide chemotherapy in patients with untreated extensive-disease small-cell lung cancer to assess response and toxicity. Between January 1994 and December 1995, 16 patients were treated. Ifosfamide and etoposide doses were ifosfamide 2 g/m2, with mesna, i.v. infusion over 30 minutes on days 1-3 and etoposide 80 mg/m2 i.v. over 120 minutes on days 1-3 every 4 weeks for up to six cycles. All patients were evaluable for toxicity profile and treatment response. As expected, the major toxicity was myelosuppression. With one exception, grade 3 or 4 leukopenia occurred in all patients during treatment, and 48.7% of the total courses had grade 3 or 4 leukopenia. Nine of 16 patients (56.3%) experienced episodes of febrile neutropenia. One toxic death due to febrile neutropenia with sepsis was documented. Toxicities other than leukopenia were few and mild in severity. After two cycles of treatment, the overall response rate was 81.3% (95% confidence interval 62.2-100) in this study. The median duration of response was 8 months and median survival was 11 months. In conclusion, ifosfamide and etoposide is an active combination regimen with acceptable toxicity profile in Chinese patients with extensive-disease small-cell lung cancer.

Aged↗

Revisit of primary malignant neoplasms of the trachea: clinical characteristics and survival analysis.

A clinical review with an analysis of prognostic factors, including clinical characteristics, histological classifications, presenting symptoms/signs and treatment modalities, was conducted in 67 patients with primary malignant neoplasms of the trachea who were seen at the Veterans General Hospital-Taipei between 1979 and 1994. The incidence of tracheal cancer was 140 times less than lung cancer during this period. Delayed diagnosis of more than 6 months after onset of symptoms occurred in one-third of the patients owing to lack of specific symptoms/signs indicative of tracheal disease. Epidermoid carcinoma was the most frequent histological type encountered and accounted for half of the cases. Surgical resection was the first choice of treatment for all patients if the disease was locally confined, except for small cell carcinoma and lymphoma. Radiotherapy was given if the patient was not suitable for surgery. Single and multivariate analyses showed that clinical symptoms and signs were not related to prognosis, except for general malaise and acute respiratory failure. Patients suffering from adenoid cystic carcinoma and mucoepidermoid carcinoma had a better prognosis than other histological diagnoses. Whether the patient received radiotherapy or not proved to be a significant prognostic factor in the patients. Patients with tracheal cancers had a poorer prognosis than those with lung cancer.

Adenocarcinoma↗

A phase I feasibility and pharmacokinetic study of intrapleural paclitaxel in patients with malignant pleural effusions.

To evaluate the feasibility and pharmacology of intrapleural (IP(L)) administration of paclitaxel, 18 patients with malignant pleural effusions were entered onto a phase I clinical study, 13 were caused by lung cancer. Following an effusion drainage rate of less than 100 ml/24 h and full expansion of the lung, patients were treated with a single instillation of pacilitaxel administered IP(L) in 500 ml of normal saline and retained for a maximum of 96h when tolerated. No systemic chemotherapy or ipsilateral thoracic irradiation was given for 4 weeks before and after the IP(L) treatment. The starting dose was 82.5 mg/m2 with the dose escalation schedule of 125, 175, 225 and 300 mg/m2. There were minimal local or systemic toxicities, such as local chest pain or myelosuppression, even when the paclitaxel dose reached 225 mg/m2. The pharmacological advantages of the IP(L) administration of paclitaxel were demonstrated by the mean exposure of the pleural cavity (area under the concentration time curve) to paclitaxel after IP(L) delivery exceeding that of the plasma by approximately 370-fold (range 55-684) and by the extraordinarily slow IP(L) clearance of paclitaxel (mean +/- SE 0.49 +/- 0.07 l/m2/day; range 0.08-1.16 l/m2/day) with significant concentrations of paclitaxel persisting within the cavity for more than 48-96 h after a single IP(L) instillation. In patients with detectable plasma paclitaxel levels, the plasma levels achieved exceed the minimal concentrations that are required to induce cytotoxic effects in vitro. Four patients had progressive dyspnea during IP(L) retention of paclitaxel solution because of treatment failure and needed drainage of effusion. One of these patients who was at the dose level of 225 mg/m2 originally had severely chronic obstructive lung disease, developed acute respiratory failure, refused mechanical ventilation support and succumbed to respiratory failure. No further patients were included after this event. Antitumor effect was shown by four of the 15 evaluable patients having no recurrence of effusion on chest radiograph at 1 month. Most of these responders had a good performance status, normal pretreatment pleural pH and/or glucose compared with the non-responders. We conclude that paclitaxel at a dose level of 175 or 225 mg/m2 is feasible for use intrapleurally. It could be considered for incorporation into treatment programs for patients with less advanced thoracic tumors with carcinomatous pleuritis or with IP(L) tumors following surgical debulking.

Adenocarcinoma↗

Restoration of the immunocompetence by IL-2 activation and TCR-CD3 engagement of the in vivo anergized tumor-specific CTL from lung cancer patients.

The present study investigates the nature of the immunosuppressed state of the lymphocytes obtained from the malignant pleural effusion (effusion associated lymphocytes, EAL) of lung cancer patients. The immunocompetence of EAL from 13 patients was assessed by determining their T-helper cell phenotype, proliferative response to alpha CD3-activation, and their cytolytic activity against three tumor targets: the autologous tumor, Daudi, and K562. Flow cytometry analysis showed that the lymphocytes in EAL were predominantly T cells with < 1% natural killer cells. The T-helper cell phenotype was found to be predominantly of Th2 type, but could be readily converted to Th1 type by culturing the EAL in vitro, and this conversion was augmented by interleukin-2 (IL-2) or IL-2 plus alpha CD3. To test the cytolytic activity of EAL, it was found that after 6-day culturing, the EAL remained in an immunosuppressed state so that they failed to kill any of the three tumor targets. Stimulation with IL-2 partially restored the immunocompetence of EAL. Further engagement of TCR-CD3 by alpha CD3 fully restored the cytolytic activity of the EAL to kill the autologous tumor target but not Daudi or K562 tumor cells, and thus seemed to be tumor specific. The specificity was further confirmed by testing the activated EAL and normal donor peripheral blood lymphocytes against a variety of tumor targets and control targets. Furthermore, the killing by EAL against the autologous tumor target seemed to be major histocompatibility complex-restricted and was inhibited by anti-human leukocyte antigen class I antibody. The EAL from lung cancer patients also showed much reduced responsiveness to the alpha CD3 stimulation to induce proliferation, and addition of IL-2 restored the responsiveness. These results suggest that, through close contact with tumor cells, anergy of cytotoxic T lymphocytes (CTLs) was induced in vivo at a localized site. IL-2 stimulation and TCR-CD3 engagement could reverse the anergic state and restored the full competence of CTLs in EAL to mediate the specific anti-tumor killing against the autologous tumor. Proper manipulation of EAL may prove useful as a source of anti-tumor effectors for cancer adoptive immunotherapy.

Aged↗

A logistic regression model for the decision to perform access surgery.

Access surgery may be recommended to about 80% of patients who present with advanced forms of periodontal disease. In this report, a multivariate logistic regression analysis which incorporated several clinical parameters for each tooth examined, i.e., tooth type, furcation involvement, bleeding on probing, attachment level, probing depth, mobility and BANA test score, was conducted using generalized estimating equations (GEE). This approach identified parameters that were significantly associated at p < 0.05 level with the need for access surgery or extraction for periodontal purposes. The estimated probabilities derived from the GEE model were plotted over the complete spectrum of operating conditions to obtain a receiver-operator characteristic (ROC) curve. At a probability cutpoint of 0.8, the decision threshold for surgery/extraction at the pretreatment examination would have a sensitivity of 76.1% and a specificity of 75.3%. We have taken this 0.8 cut point to look at specific clinical decisions made by our examiners after the patients had received scaling and root planing plus 2 weeks unsupervised usage of systemic antimicrobials. The clinicians' decision was taken as the primary reference standard. The model's estimated decision agreed with the clinicians' decision in 226 of the 284 teeth, for an accuracy of 80%. The specificity was 90% and the sensitivity was 43%.

Algorithms↗

Extracellular matrix proteins modulate human peritoneal mesothelial cell behavior.

Human peritoneal mesothelial cells lie on a basement membrane-like material consisting of fibronectin (FN), type I collagen (CI), type III collagen (CIII) and laminin (LA). To understand how these extracellular matrix (ECM) proteins affect mesothelial cell behavior, we investigated their effect on the adhesion and proliferation of mesothelial cells. A modified methyltetrazolium dye method was used to assess cell number. The results showed that FN, CI, CIII and LA, all increased adhesion of mesothelial cells. The adhesive effect was blocked dose-dependently by a synthetic Arg-Gly-Asp-containing (RGD) peptide. When coated as a substratum (immobilized form), FN, CI, CIII and LA, all enhanced serum-stimulated and epidermal-growth-factor-stimulated cellular proliferation as compared with bovine-serum-albumin-blocked plastic surfaces. When added in a soluble form, all matrix proteins except FN inhibited serum-stimulated and epidermal-growth-factor-stimulated cellular proliferation at high concentrations (CI and CIII: 1-10 micrograms/ml, LA: 3-10 micrograms/ml). We conclude that peritoneal mesothelial cells possess an RGD-sensitive receptor and that the ECM can modulate adhesion and proliferation of peritoneal mesothelial cells. The growth-modulating effect depends on the form and concentration of the ECM proteins.

Cell Adhesion↗