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Biomedical subjects

C C Tai

Publications and source records attributed to C C Tai.

32 records · Page 2Linked to original sources
PubMed1997

Hyperdynamic circulation in prehepatic portal hypertension: role of tumor necrosis factor-alpha.

BACKGROUND: Portal hypertension is associated with a hyperdynamic circulation characterized by increased cardiac output and reduced systemic vascular resistance. Tumor necrosis factor-alpha (TNF-alpha) is a peptide mediator released by mononuclear cells on activation by endotoxin, tissue injury and malignancy. This cytokine induces vasodilatation by activating nitric oxide synthesis. The aim of this study is to investigate if TNF-alpha is involved in the pathogenesis of hyperdynamic circulation observed in portal vein-ligated (PVL) rats. METHODS: Systemic and portal hemodynamics were determined in seven PVL and five sham-operated (SHAM) rats using a thermodilution technique. In addition, plasma TNF-alpha concentrations were determined in another 34 PVL and 16 SHAM rats using commercially available enzyme-linked immunosorbent assay. RESULTS: PVL rats had a significantly lower mean arterial pressure (109 +/- 17 mmHg vs. 133 +/- 12 mmHg, p < 0.001) and systemic vascular resistance (2.5 +/- 0.6 mmHg.ml-1.min.100 g BW vs. 4.6 +/- 0.8 mmHg.ml-1.min.100 g BW, p < 0.001) accompanied by a significantly higher portal pressure (14 +/- 1.9 mmHg vs. 9 +/- 2.1 mmHg, p < 0.001) and cardiac index (47.0 +/- 12.1 ml.min-1.100 g BW-1 vs. 29.3 +/- 3.5 ml.min-1.100 g BW-1, p < 0.001) when compared with SHAM rats. Also, PVL rats had significantly higher plasma levels of TNF-alpha as compared with SHAM rats (13.8 +/- 0.9 pg/ ml vs. 11.1 +/- 0.5 pg/ml, p < 0.05). CONCLUSIONS: This study suggests that elevated plasma levels of TNF-alpha observed in PVL rats may participate in the development and/or maintenance of the hyperdynamic circulation occurring in prehepatic portal hypertension.

Animals↗
PubMed1994

Nasal septum lesions caused by chromium exposure among chromium electroplating workers.

A chromium electroplating worker, suffering from epistaxis during work, was found to have nasal septum perforation. To determine the etiology and prevalence of nasal septum lesions, we conducted a survey of seven chromium electroplating factories and examined 79 workers. Forty workers from three aluminum electroplating factories were also enrolled as the reference group. Subjects were thoroughly examined by an otolaryngologist and each of them provided a blood and urine sample. A questionnaire interview regarding symptoms of the upper respiratory tract, past medical history, life style, and work history was also conducted. Air chromium concentrations were measured by taking area samples for 4-6 hours. Based on field observation and chromium measurements, we divided chromium electroplating into three different exposure zones: workers directly dealing with electroplating tanks (n = 31), other process workers (n = 29), and office workers and drivers (n = 19). Among the 79 chromium electroplating workers, there were 16 cases of nasal septum perforation, and 42 with either scar formation or ulceration; 10 chromium electroplating workers developed skin ulcers after performing chrome plating. No workers from aluminum electroplating factories had any nasal septum or skin abnormalities. There was a consistent trend between the degree of chromium exposure and the signs and symptoms related to the nose, throat, and skin. Immediate improvement of occupational hygiene is warranted.

Adult↗
PubMed1994

Prophylactic extraction of third molars in cancer patients.

Most studies on third molar extractions focus on the potential of tooth-associated pathoses when justifying or questioning the extraction. Scant attention is paid to potential medical problems of the patient "attached" to the third molar. This study presents 28 consecutive cancer cases seen by one dentist over a 2-year period in which third molars had a significant impact on the health of the patient and on their course of cancer therapy. In 15 patients on whom extractions were performed, 40% experienced postoperative complications. Prophylactic extraction of partially erupted or impacted third molars in cancer patients before their cancer therapy is recommended on the basis of the following observations: (1) the increased risks and difficulties associated with post-cancer-treatment extraction, (2) the potential for third molars to produce pathoses in immunocompromised patients before, during, or immediately after their anticancer treatment, and (3) the management of third molars may interfere with the patient's cancer treatment.

Adolescent↗
PubMed1994

Digitized slice interposition in forensic dental radiographic identification. An in vitro study.

Traditional methods of comparison involving the presence of missing teeth, dental restorations, and other pathological features may be difficult due to the reduction in dental restorations in today's population. This study demonstrates an alternative method of identification using digitized images. It utilizes anatomical structures such as dental root morphology and spatial relations of teeth roots and their supporting structures on simulated antemortem and postmortem radiographs as the basis for identification. A total of 39 mandibular specimens were used and two radiographs representing the antemortem and postmortem radiographs of each hemimandible were exposed by two operators using different x-ray generators. The radiographs were scanned and digitized. The identities of the antemortem and postmortem radiographs were kept from the operator. Following this, horizontal sections were digitally cut from the antemortem radiographs through the roots approximately halfway between the neck of the tooth and the root apex. This section was manipulated onto the postmortem radiograph by using a computer graphics program and a quantitative comparison of the alignment of normal dental anatomical landmarks was undertaken. The technique enabled perfect matching of all 39 specimens by antemortem and postmortem dental radiographs. The mean number of identifying points was 17.5 and the mean number of nonmatching points was 0.1. The mean concordance was 99.2% between the antemortem and postmortem radiographs.

Forensic Dentistry↗
PubMed1994

The occlusal radiograph revisited.

The purpose of this paper is to demonstrate occlusal radiography as an important projection for diagnostic purposes in general dental practice. There are many instances where bitewing and periapical radiographs are insufficient to demonstrate pathoses adequately. A descriptive and photographic review of the different occlusal projections and a series of illustrative cases demonstrating their diagnostic relevance is provided.

Humans↗
PubMed1993

Dental radiographic identification utilising computerised digital slice interposition: a case report.

A pair of ante- and post-mortem periapical dental radiographs of an individual were digitised on a personal computer with the aid of an X-ray scanner. The radiographs were appropriately prepared and compared using image editing software. In this case, dental restorations, root morphology, periodontal ligaments, pulp spaces, bony trabeculation and a retained root fragment were features used for comparison. The results showed that all the features were consistent in ante-mortem and post-mortem radiographs except for two points. Both discrepancies were related to dimensional differences found in dental restorations and the retained root fragment. Nevertheless, there were acceptable explanations to account for each discrepancy.

Female↗
PubMed1992

A PC-based imaging system for automated platelet identification.

In this communication, a PC-based imaging system was developed for automatically identifying fluorescence-labeled individual platelets adherent to protein-coated surface under flow conditions. It is to eliminate the laborious and time-consuming task, and the subjective error of manual measurements. Based upon the features of adherent platelets, three passes of the image processing were developed for platelet identification. From the results, 90-95% accuracy could be routinely obtained. The platelet distribution and other related parameters could be easily extracted and investigated.

Algorithms↗
PubMed1990

Development and evaluation of a human T-cell leukemia virus type I serologic confirmatory assay incorporating a recombinant envelope polypeptide.

A recombinant protein derived from the gp21 region of the human T-cell leukemia virus type I (HTLV-I) env gene was synthesized in Escherichia coli and purified by reversed-phase high-performance liquid chromatography. The purified protein was free of contaminating bacterial proteins and retained reactivity with human HTLV-I- and HTLV-II-positive sera and a gp21 monoclonal antibody. An immunoblot procedure using the recombinant polypeptide in conjunction with native viral proteins was more sensitive than the conventional immunoblot and radioimmunoprecipitation confirmatory assays for detection of antibodies to HTLV-I and HTLV-II env-encoded gene products. The recombinant protein was equally reactive with sera from polymerase chain reaction-confirmed HTLV-I or HTLV-II infections. Furthermore, on the basis of the differential reactivities of gp21-positive sera with the HTLV-I p19 and p24 gag-encoded proteins, an algorithm was proposed to distinguish exposure to HTLV-I from exposure to HTLV-II. These results establish the utility of a modified immunoblot assay incorporating a recombinant envelope polypeptide as an alternative to existing HTLV-I-confirmatory assays.

Antibodies, Viral↗
PubMed1985

Importance of western blot analysis in predicting infectivity of anti-HTLV-III/LAV positive blood.

Stored donor and recipient sera from prospective studies of post-transfusion hepatitis were analysed for the presence of human T-cell lymphotropic virus type-III/lymphadenopathy associated virus (HTLV-III/LAV) antibodies as determined by enzyme-linked immunosorbent assays (ELISA). Of 3961 donor samples given to 461 patients, only 2 (0.05%) contained specific HTLV-III/LAV antibodies as determined by an avidin-biotin-enhanced western blot tech nique. Anti-HTLV-III/LAV was measured before and 3 and 6 months after transfusion in 295 recipients of anti-HTLV-III-negative blood, 7 recipients of ELISA-positive blood which was western blot negative, and 2 recipients of ELISA-positive blood confirmed as specific by western blot. Only the last 2 recipients became infected with HTLV-III/LAV, as assessed by antibody seroconversion (p less than 0.0001). Serocon version occurred early (6 and 8 weeks after transfusion) and was characterised first by antibody to p24 and later by antibody to p41. AIDS has not developed in either patient, but one has a T4/T8 ratio of 0.4 and impaired mitogen responses; the second patient has no evidence of immune dysfunction 4 years after exposure. This study confirms that HTLV-III/LAV infection can be transmitted by blood transfusion and supports the advisability of anti-HTLV-III/LAV testing of all blood donors. It also confirms the validity of western blot testing for HTLV-III/LAV specificity and suggests that ELISA-positive, western-blot-negative blood may not be infectious.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Progressive systemic sclerosis in a child: case report.

A case of pediatric progressive systemic sclerosis is reported and a literature review concerning medical and dental aspects of this condition is provided. Systemic features include sclerodactyly, Raynaud's phenomenon, telangiectasia, calcinosis, myositis, arthritis, tenosynovitis, renal failure, esophageal hypomotility, pulmonary fibrosis and heart failure. Oral manifestations include reduced interincisal distance, xerostomia, telangiectasia, increased periodontal ligament width, osseous resorption of the mandible, periodontal disease, and increased decayed, missing, and filled teeth (DMFT). The prognosis is difficult to predict because spontaneous remission has been documented, but death may result from extensive visceral involvement (heart, kidney, and lung).

Child↗