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Biomedical subjects

J C Lin

Publications and source records attributed to J C Lin.

At least 73 records · Page 4Linked to original sources
PubMed1999

Trabecular bone architecture in the distal radius using magnetic resonance imaging in subjects with fractures of the proximal femur. Magnetic Resonance Science Center and Osteoporosis and Arthritis Research Group.

To determine whether magnetic resonance (MR)-derived measures of trabecular bone architecture in the distal radius are predictive for prevalent hip fractures, 20 subjects with hip fractures and 19 age-matched postmenopausal controls were studied. Bone mineral density (BMD) measures at the hip (dual-energy X-ray absorptiometry, DXA) and the distal radius (peripheral quantitative computed tomography, pQCT) were also obtained. We compared the MR-based structural measures derived in the radius with those in the calcaneus of the same patients. In the radius, images were acquired at an in-plane resolution of 156 microm and a slice thickness of 0.5 mm. Stereologic measures such as the apparent trabecular thickness (app. Tb.Th), fractional trabecular bone volume (app. BV/TV), trabecular spacing (app. Tb.Sp) and trabecular number (app. Tb.N) were derived from the images. Measures of app. Tb.Sp and app. Tb.N in the distal radius showed significant (p<0.05) differences between the two groups, as did hip BMD measures. However, radial trabecular BMD measures showed only a marginal difference (p = 0.05). Receiver operating curve analysis was used to determine the diagnostic efficacy of BMD, structural measures and a combination of the two. The area under the curve (AUC) for total hip BMD was 0.73, and for radial trabecular BMD was 0.69. AUC for most of the measures of trabecular bone structure at the distal radius was lower than for hip BMD measures; however, AUC for app. Tb.N at the radius was 0.69, comparable to trabecular BMD using pQCT. The AUC for combined BMD (hip) and structure measures was higher (0.87) when radius and calcaneus structure was included. Measures of trabecular architecture derived from MR images combined with BMD measures improve the discrimination between subjects with hip fractures and normal age-matched controls.

Aged↗
PubMed1999

Cardiac pheochromocytoma: resection after diagnosis by 111-indium octreotide scan.

Cardiac pheochromocytoma is an exceedingly rare and unusual clinical entity. Only 37 previous surgically treated adult patients were found in review of the surgical literature. We report the case of a 13-year-old boy who had a cardiac pheochromocytoma that was localized by the 111-indium diethylenetriamine pentaacetic acid octreotide scintigraphy scan and confirmed by magnetic resonance imaging after computed tomographic and B1-iodine-metaiodobenzylguanidine scans had failed. At operation, a 6-cm pheochromocytoma of the left atrium was found and successfully resected with reconstruction of the left atrium using autologous pericardium.

Adult↗
PubMed1999

Finding the LAD during MIDCAB operations.

Minimally invasive direct coronary artery bypass (MIDCAB) is a new surgical procedure that revascularizes the left anterior descending coronary artery (LAD) without the need for a median sternotomy or cardiopulmonary bypass. This operation is performed through a small left anterior thoracotomy. With this exposure, it can be difficult to locate the left anterior descending coronary artery. We have identified anatomic features on the surface of the pericardium that can serve as a landmark for finding the left anterior descending coronary artery.

Coronary Artery Bypass↗
PubMed1999

Surface properties and hemocompatibility of alkyl-siloxane monolayers supported on silicone rubber: effect of alkyl chain length and ionic functionality.

Self-assembled monolayers of alkylsiloxanes supported on poly(dimethylsiloxane) (PDMS) rubber were used as model systems to study the relation between blood compatibility and surface composition. The inner lumen of PDMS tubes were first treated with an oxygen plasma. The resultant oxidized surfaces were post-derivatized by reaction with alkyltrichlorosilanes to form the monolayer films. The alkyl chain lengths used were slightly longer than in a previous study, and this may alter the phase-state of the monolayer from liquid-like to crystalline. The chemical properties of the monolayer were controlled by varying the chemical composition of the alkyltrichlorosilanes used. Terminal functionalities included -CH3, -CF3, -COOH, -SO3H and -(CH2CH2O)4OH. Surface derivatization was verified with static contact angle measurements and X-ray photoelectron spectroscopy. Blood compatibility was evaluated using a canine ex vivo arterio-venous series shunt model. Surfaces grafted with hydrophobic head groups such as -CH3 and -CF3 were significantly less thrombogenic than the surfaces composed of ionic head groups such as -COOH and -SO3H. Surfaces enriched in -(CH2CH2O)4OH had an intermediate thrombogenicity. Silastic pump grade tubing and polyethylene tubing, used as controls, were found to be the least thrombogenic of all the surfaces tested.

Animals↗
PubMed1999

Surface characterization and platelet adhesion studies of plasma polymerized phosphite and its copolymers with dimethylsulfate.

Due to its capability for using a wide variety of organic and inorganic compounds as the monomer source, including those which are not polymerizable by conventional methods, plasma polymerization has been used to incorporate various functional groups onto the substrates of interest. Plasma polymerization of trimethylphosphite and triisopropylphosphite was attempted with an aim to deposit a thin film with phosphorous-containing functional groups such as phosphate or phosphite onto the glass substrate. Sulfur-containing functional groups, such as sulfonate, were incorporated as well with the addition of dimethylsulfate to the phosphite monomer inlet. These plasma polymers and plasma copolymers were very hydrophilic. Incomplete surface coverage was noticed under the processing conditions of low phosphite flow rate, low RF input power and shorter deposition time. Extended deposition duration and higher power input resulted in the formation of voids and pits on the plasma polymer surface. In addition, the surface coverage of the plasma copolymers becomes discontinuous if the flow rate ratio of dimethylsulfate to triisopropylphosphite is too high. In vitro platelet adhesion studies indicated the plasma polymers and plasma copolymers with continuous surface coverage are less platelet activating than the glass control. Moreover, the addition of dimethylsulfate into the phosphite monomer flow led to a further reduction in platelet adhesion and activation than the comparable one. This may be attributed to the effect of the sulfur-containing functionalities, such as sulfonate or sulfate, found on the plasma copolymers.

Alkylating Agents↗
PubMed1999

Surface characterization and platelet adhesion studies on polyurethane surface immobilized with C60.

Due to its distinctive molecular configuration, C60 and its derivatives have been the research focus in exploring its electrical, mechanical, optical, and even biological applications during the past decades. In this investigation, C60 molecules are grafted onto the polyurethane surface, which is pretreated with oxygen plasma activation, through amine-terminated silane coupling agents. ESCA analysis indicates that the C60 molecules spontaneously grafted onto the amine-terminated PU substrate through nucleophilic additions to the fullerene double bonds which fuse two six-membered rings. More amine functional groups are formed on the PU surface if 4-aminobutyldimethylmethoxysilane is used as the coupling agent. In vitro platelet adhesion assay shows the C60 grafted PU are more platelets activating than the nontreated PU control. This might be attributed to the synergistic effect of the grafted C60 molecules and the few residual amine functional groups which are left after the C60 grafting reaction. Further applications using these C60 grafted polyurethane surfaces as the cell adhesion and cell growth substrates are currently under exploration.

Amines↗
PubMed1999

Measurement of intraspecimen variations in vertebral cancellous bone architecture.

A three-dimensional technique was developed for the quantification of the number and cross-sectional geometry of individual trabeculae oriented along a given direction. As an example application, the number of vertical and horizontal trabeculae and their respective cross-sectional geometry were determined for a set of six vertebral cancellous bone specimens (L3-L4 female vertebral bodies; age range 39-63 years). Three-dimensional optical images at a spatial resolution of 20 microm were obtained using an automated serial milling technique. The thickness distributions were generally right skewed. The mean true thickness for both the vertically and horizontally oriented trabeculae showed a strong relationship with volume fraction (vertical: r2 = 0.86; p < 0.05; horizontal: r2 = 0.80; p < 0.05), and mean trabecular thickness (Tb.Th.) (vertical: r2 = 0.81; p < 0.05; horizontal: r2 = 0.72; p < 0.05). The horizontal trabeculae were greater in number and were thinner than the vertical trabeculae. The coefficient of variation of the intraspecimen vertical trabecular thicknesses ranged from 25% to 42%, and showed a weak, albeit insignificant, positive correlation with volume fraction (r2 = 0.46). The findings demonstrated substantial intraspecimen variations exist in trabecular thickness that are not related to volume fraction. Further studies are recommended to determine the potential role of such intraspecimen variations in architecture on biomechanical properties.

Adult↗
PubMed1999

Recent clinical experience with left heart bypass using a centrifugal pump for repair of traumatic aortic transection.

OBJECTIVE: To analyze the indications, results, and limitations of using left atrial to femoral artery (LA-FA) bypass to provide distal perfusion during repair of traumatic aortic injuries. SUMMARY BACKGROUND DATA: There is no consensus about the best method for repair of traumatic aortic transection. Distal aortic perfusion with LA-FA bypass and a centrifugal pump has been the authors' preferred technique for injuries to the aortic isthmus and descending thoracic aorta. METHODS: From 1988 to 1998, the authors operated on 30 patients with traumatic aortic transection using LA-FA bypass. The mean age of the group was 36+/-2 years. The mechanism of injury was from a motor vehicle accident in 97% of the cases. Distal aortic perfusion was maintained at 50 to 75 mm Hg with flow rates of 1.5 and 3 L/min. The mean aortic cross-clamp time was 38+/-2 minutes, and the mean bypass time was 49+/-2 minutes. RESULTS: No complications related to cannulation, arterial thromboembolism, renal failure, mesenteric ischemia, or hepatic insufficiency occurred. There were no cases of postoperative paraplegia and no deaths. CONCLUSION: Left atrial to femoral artery bypass is a safe, simple, and effective adjunct to the repair of traumatic injuries to the thoracic aorta. Active distal aortic perfusion preserves spinal cord, mesenteric, and renal blood flow and eliminates the potential catastrophic consequence of spinal cord ischemia from an unexpectedly prolonged aortic cross-clamp time.

Adolescent↗
PubMed1999

Multicenter comparison of PCR assays for detection of human herpesvirus 8 DNA in semen.

Reported prevalences of human herpesvirus 8 (HHV-8) (Kaposi's sarcoma-associated herpesvirus) in semen have ranged widely. This is possibly due to differences in assay sensitivity, geographic or population-based differences in the true presence of the virus in semen, and PCR contamination. This study assessed interlaboratory sensitivity and reproducibility in the analysis of blinded experimental panels, each consisting of 48 specimens and being composed of semen specimens from different healthy artificial-insemination donors (n = 30) and human immunodeficiency virus (HIV)-infected patients (n = 7) plus positive (n = 4) and negative (n = 7) controls. The experimental panels analyzed in each laboratory were identical except for being independently coded. Of 10 experiments done in five laboratories, 5 experiments from three laboratories had evidence of PCR contamination; all instances of contamination were in the context of nested PCR procedures. In the experiments with no false-positive results, HHV-8 DNA was detected in three (8%) of the 37 semen specimens (two from artificial-insemination donors and one from an HIV-positive patient) but in only 3 (1.6%) of the 184 PCRs in which these specimens were analyzed. This suggests that HHV-8 DNA is present in semen at concentrations that can be too low to allow its consistent detection. This study emphasizes the importance of performing blinded, multi-institution experiments to provide a coherent basis for comparing results and to motivate standardization of methods.

DNA, Viral↗
PubMed1999

Locally advanced nasopharyngeal cancer: long-term outcomes of radiation therapy.

PURPOSE: To investigate the clinical manifestations and treatment outcomes in patients with stage T4M0 nasopharyngeal carcinoma. MATERIALS AND METHODS: Findings in 179 patients (age range, 13-78 years) with American Joint Committee on Cancer stage T4M0 nasopharyngeal carcinoma treated from January 1983 to February 1992 with a minimum follow-up of at least 5 years were reviewed. Of the 179 patients, 166 (92.7%) had World Health Organization type II or III disease. Forty-one patients (22.9%) had no lymph nodal involvement; 138 patients (77.1%) had metastatic nodal involvement in the neck. All patients underwent radiation therapy; 39 patients also received different forms of chemotherapy. The radiation therapy doses were usually 70-74 Gy administered to the primary tumor over 7 or 8 weeks, 70-74 Gy to the neck region in patients with nodal involvement, or 50-60 Gy administered to the neck region over 5 or 6 weeks in patients without neck nodal involvement. RESULTS: In 100 patients, radiation therapy failed in the primary tumor alone (n = 28), neck nodes alone (n = 5), and distant metastases alone (n = 43) or at a combination of sites (n = 24). The cumulative failure rates for the primary tumor, neck metastases, and distant metastases were 25.1% (n = 45), 14.0% (n = 25), and 33.0% (n = 59), respectively. The 5-year primary disease-free, distant disease-free, and overall survival rates were 68.7%, 56.5%, and 28.6%, respectively. Results of salvage treatment for relapse were unsatisfactory. CONCLUSION: In about three-tenths of patients, T4M0 nasopharyngeal carcinoma can be cured with conventional high-dose radiation therapy.

Adolescent↗
PubMed1999

The effect of converting from pravastatin to simvastatin on the pharmacodynamics of warfarin.

Forty-six adult patients maintained on warfarin therapy were converted from pravastatin to simvastatin. Mean international normalized ratio (INR) significantly increased from 2.42 to 2.74, p = 0.002. Although warfarin doses were reduced in 7 patients and increased in 4 patients following the post-conversion INR measurements, the pre- and postconversion median weekly warfarin dose of all 46 patients did not differ significantly. The number of patients with an INR > 3.0 increased significantly from 6 to 16 following the conversion. There was no report of unusual episodes of bleeding. The results indicate that antihyperlipidemic therapy can be changed safely from pravastatin to simvastatin in patients who are taking warfarin concomitantly. Additional anticoagulation monitoring is not necessary in institutions where patients are followed in formal anticoagulation clinics.

Aged↗
PubMed1999

Chronic creatine kinase elevation not associated with HMG-CoA reductase inhibitor treatment.

OBJECTIVE: To report a case of chronically elevated creatine kinase (CK) concentration that is possibly associated with renal insufficiency and prostatic carcinoma. The goal is to raise awareness among clinicians who monitor CK concentrations in patients receiving hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors. CASE SUMMARY: Because of an elevated CK concentration, a 64-year-old African-American man with a history of chronic heart disease and renal insufficiency was assessed for possible myositis relating to his treatment with HMG-CoA reductase inhibitors. However, an association between the elevated enzyme concentration and drug treatment could not be clearly established. The patient was subsequently diagnosed with prostatic cancer and underwent a radical retropubic prostatectomy. The CK enzyme concentration declined following the surgery despite continuation of the drug therapy. DISCUSSION: CK is relatively nonspecific because of its wide distribution in human tissues. Although several findings of elevated CK concentrations, particularly the CK-BB isoenzyme, in patients with carcinoma or chronic renal insufficiency have been documented, these may not be common knowledge among clinicians. This case report provides an example of an unusually high CK enzyme concentration that may be linked to prostatic carcinoma and renal insufficiency. CONCLUSIONS: It is important to be aware of different causes for CK enzyme concentration elevation, especially when it is used as a monitoring parameter during HMG-CoA reductase inhibitor treatment. In a case of persistent elevated CK enzyme concentration without evidence of myositis, renal insufficiency may be a contributing factor and malignancy must be ruled out.

Biomarkers, Tumor↗
PubMed1999

The experience to use a modified en bloc excision technique in vitrectomy for diabetic traction retinal detachment.

Modified en bloc excision is a technique in which all posterior hyaloid is excised except the portions essential for membrane dissection. Then, bimanual dissection techniques allow excision of retained fibrovascular membrane "en bloc" with hyaloid. In a consecutive series of 16 eyes with diabetic traction retinal detachment treated with this technique, visual acuity of 5/200 or better was obtained in 11 (69%) of the cases, and complete macula reattachment was noted in 14 (87%) of 16 eyes. The final visual acuity was improved in 12 (75%) cases. While this surgical technique allows a higher rate of anatomic success and less postoperative morbidity, visual results remain limited by irreversible alteration in retinal function.

Adult↗
PubMed1999

Diagnostic and therapeutic video-assisted thoracic surgery resection of pulmonary metastases.

BACKGROUND: Appropriateness of video-assisted thoracic surgery (VATS) pulmonary metastasectomy for curative intent has been a controversial topic. We reviewed our experience with VATS wedge resection for peripheral lung metastases to determine the efficacy and potential adverse consequences of this approach for pulmonary metastasectomy. METHODS: One hundred seventy-seven patients underwent VATS resection of pulmonary metastases. Diagnostic resection (VATS-dx) was performed for 78 patients when percutaneous biopsy was unsuccessful or not feasible. Potentially curative resections (VATS-rx) were performed for 99 patients. The histologic findings in this group included colorectal (68), renal (7), sarcoma (6), breast (4), melanoma (3), head/neck (3), lymphoma (2), uterine (1), and "other" (5). The average number of lesions resected was 1.4 (range, 1-7). RESULTS: VATS resection was successfully performed for all VATS-dx and VATS-rx patients. There were no perioperative deaths. Longitudinal follow-up demonstrated a mean survival of 18 months in the VATS-dx group and 28 months in the VATS-rx group. In the VATS-rx group, 37 (37%) of 99 were free of disease, at a mean follow-up interval of 37 months. Of the 57 recurrences, 5% were local, 26% were regional, and 69% were distant. CONCLUSIONS: Results with VATS resection of peripheral pulmonary metastases for diagnostic and potentially curative intentions appear comparable with historical results by "open" thoracotomy. Careful patient selection based on high-resolution helical CT scanning is important to avoid compromise of therapeutic intent. Conversion to thoracotomy is indicated when lesions identified preoperatively are not found or when technical problems encountered may compromise surgical margins when resecting lung metastases for potential cure.

Adult↗
PubMed1999

Failure of screening to detect HIV in a foreign laborer who died of toxoplasmosis of the central nervous system.

The most common neurologic complication in patients with acquired immunodeficiency syndrome (AIDS) is cerebral toxoplasmosis. Patients with cerebral toxoplasmosis have characteristic findings on clinical examination and neuroimaging. They require prolonged treatment and have a considerable mortality rate. We report a case of cerebral toxoplasmosis in a foreign laborer with AIDS, in whom a human immunodeficiency virus (HIV) screening test failed to detect-HIV infection. The patient, a 23-year-old man from Thailand, presented in a confused state 2 weeks after his arrival in Taiwan. Computed tomography showed a mass effect, and magnetic resonance imaging showed multiple ring-enhanced lesions in the cerebrum. Serologic tests were positive for anti-HIV antibody and also showed high anti-Toxoplasma immunoglobulin G titers. Although symptomatic treatment was initiated, the patient's condition deteriorated rapidly and he died of multiple organ failure due to brain stem herniation a few days after admission. As the number of foreign laborers working in Taiwan has increased dramatically in recent years, the issues raised by this case are the efficacy of our screening protocols for foreign laborers and the increased occupational hazards encountered by medical personnel in Taiwan.

AIDS Serodiagnosis↗
PubMed1999

Non steroidal anti-inflammatory drug-based pain control for minimally invasive direct coronary artery bypass surgery.

Minimally invasive direct coronary artery bypass (MIDCAB) surgery has become an attractive alternative technique to treat coronary artery insufficiency. Changes in surgical and anesthesia techniques have led to reduced pulmonary morbidity associated with the operation. Early extubation is typically expected. However, postoperative pain management becomes even more important with early extubation. We describe our technique of a NSAID-based protocol with indomethicin and Torodal that has been safe and effective in over 175 patients following MIDCAB.

Anti-Inflammatory Agents, Non-Steroidal↗