PubMed Health⌕ Search

Biomedical subjects

A C Lin

Publications and source records attributed to A C Lin.

At least 19 recordsLinked to original sources
PubMed2002

A novel sample holder allowing atomic force microscopy on transmission electron microscopy specimen grids: repetitive, direct correlation between AFM and TEM images.

A novel sample holder that allows atomic force microscopy (AFM) to be performed on transmission electron microscope (TEM) grids is described. Consequently, AFM and TEM images were repeatedly obtained on exactly the same sample area. For both techniques, a thin carbon film was used as the imaging substrate. Although these techniques have been previously used in conjunction, AFM and TEM images on exactly the same area have not been repeatedly obtained for any system. Correlation of AFM and TEM images is useful for work where the three-dimensional topographical information provided by the AFM could be used to better interpret the two-dimensional images provided by the TEM and vice versa. To demonstrate the applicability of such correlation, new results pertaining to a fibrillar collagen system are summarized.

Fibrillar Collagens↗
PubMed2001

Successful external cardioversion of atrial fibrillation in patients referred to an electrophysiologist for internal cardioversion.

BACKGROUND: Internal cardioversion of atrial fibrillation with direct current energy has become an increasingly employed technique for patients who fail external cardioversion. HYPOTHESIS: The purpose of this study was to determine whether internal cardioversion could be avoided by careful attention to cardioversion technique in a group of patients referred specifically for internal cardioversion after failed external cardioversion by community cardiologists. METHODS: We performed external cardioversion utilizing two operators applying significant pressure to the thorax with up to 360 J prior to the planned internal cardioversion in 20 patients referred for internal cardioversion after failed attempts at external cardioversion. RESULTS: Sixteen patients (80%) were successfully cardioverted and avoided the risk, inconvenience, and cost of internal cardioversion. CONCLUSION: External cardioversion with significant anterior paddle pressure by two operators can decrease the need for internal cardioversion in a significant portion of patients referred to electrophysiologists for internal cardioversion and should be considered prior to an invasive procedure.

Atrial Fibrillation↗
PubMed2001

Arthroscopic suture tying: A comparison of knot types and suture materials.

PURPOSE: The purpose of this study was to determine the structural properties of 3 arthroscopically tied knots using 2 different suture materials: the French knot, the Duncan loop knot, and the original Revo knot. TYPE OF STUDY: Cohort analytic study. METHODS: The sutures used were No. 1 PDS II, an absorbent monofilament, and No. 1 Ethibond (Ethicon, Somerville, NJ), a braided nonabsorbent material. The resulting 6 suture-knot combinations were individually tested to failure in both open- and closed-loop configurations. RESULTS: The French knot showed the greatest strength compared with the Duncan loop and the Revo knot with both No. 1 Ethibond and No. 1 PDS II sutures (P <.05). The No. 1 Ethibond exhibited higher initial stiffness than the No. 1 PDS II for all 3 knot types (P <.05). Results were similar for both open and closed-loop configurations. Also, the French knot failed predominantly by suture breakage instead of knot slippage for both suture materials. CONCLUSIONS: The results of this study suggest that, among the suture and knot combinations investigated in this study, the arthroscopic repair of musculoskeletal injuries should be performed using the French knot and No. 1 Ethibond suture.

Arthroscopy↗
PubMed2001

Effect of radiofrequency current on previously implanted pacemaker and defibrillator ventricular lead systems.

We compared the response of endocardial lead systems to radiofrequency (RF) current delivered during atrio-ventricular junction ablation (AVJA) for atrial fibrillation with uncontrolled ventricular rate in 107 patients. The mean age was 67 +/- 11 years and the mean ejection fraction 42 +/- 15%. Patients were divided into 3 groups based on the type of ventricular lead present at the time of ablation: a previously implanted defibrillator lead (group 3, n = 13), a previously implanted pacemaker lead (group 2, n = 46) or a temporary lead (group 1, n = 48), which was subsequently followed by a permanent lead implantation. During AVJA, a median of 5 RF applications (44 +/- 8 W) were given via 4-5-mm electrodes. All but 1 patient had right-sided lesions, while 6 patients also had left sided lesions. Ventricular pacing thresholds were evaluated immediately pre- and post-ablation at 24 hours and at 1 to 3 months. Increases in ventricular pacing voltage thresholds were noted in all 3 groups over time, with the greatest mean increase in group 3 patients: [table: see text]. A greater than 2-fold increase in pacing thresholds was observed only with previously implanted leads, usually within the first 48 hours. It occurred significantly more often in patients with group 3 (6/13 [46%]) compared to group 2 (6/46 [13%], odds ratio 7.6, P = 0.006). A progressive rise in pacing threshold required lead revision in 2/13 group 3 patients (15%) and 2/46 group 2 patients (4%). While RF current has only minor effects on pacing threshold in most patients with previously implanted ventricular lead systems, clinically important alterations requiring device reprogramming or lead revision may occur. Group 3 are significantly more vulnerable to RF current, though the mechanisms are unclear. Group 1 during AVJA, followed by permanent lead implantation appears advisable. Pts with a previously implanted group 3 who require AVJA should be monitored closely.

Aged↗
PubMed2000

Atypical atrial flutter originating in the right atrial free wall.

BACKGROUND: Data from experimental models of atrial flutter indicate that macro-reentrant circuits may be confined by anatomic and functional barriers remote from the tricuspid annulus-eustachian ridge atrial isthmus. Data characterizing the various forms of atypical atrial flutter in humans are limited. METHODS AND RESULTS: In 6 of 160 consecutive patients referred for ablation of counterclockwise and/or clockwise typical atrial flutter, an additional atypical atrial flutter was mapped to the right atrial free wall. Five patients had no prior cardiac surgery. Incisional atrial tachycardia was excluded in the remaining patient. High-density electroanatomic maps of the reentrant circuit were obtained in 3 patients. Radiofrequency energy application from a discrete midlateral right atrial central line of conduction block to the inferior vena cava terminated and prevented the reinduction of atypical atrial flutter in each patient. Atrial flutter has not recurred in any patient (follow-up, 18+/-17 months; range, 3 to 40 months). CONCLUSIONS: Atrial flutter can arise in the right atrial free wall. This form of atypical atrial flutter could account for spontaneous or inducible atrial flutter observed in patients referred for ablation and is eliminated with linear ablation directed at the inferolateral right atrium.

Aged↗
PubMed1999

Retrograde fast pathway ablation for atrioventricular nodal reentry associated with markedly prolonged PR intervals.

Three patients with typical atrioventricular nodal reentrant tachycardia (AVNRT) and markedly prolonged PR intervals (>300 ms) without dual pathway physiology at baseline or during isoproterenol infusion underwent successful fast pathway ablation and remained asymptomatic without recurrent AVNRT, atrioventricular block, or symptomatic bradycardia for a mean of 19 months. In patients with recurrent AVNRT and markedly prolonged PR intervals, selective ablation of the retrograde fast pathway can eliminate AVNRT without further impairment of anterograde atrioventricular nodal function.

Adrenergic beta-Agonists↗
PubMed1997

Endemic blastomycosis in Mississippi: epidemiological and clinical studies.

In order to clarify the epidemiology and clinical spectrum of endemic blastomycosis, we reviewed the charts of 326 culture and/or histologically proven cases of blastomycosis in Mississippi from 1979 to 1988. Cases were dispersed throughout the state, but counties in central and south-central Mississippi reported 63% of all blastomycosis cases. The average annual incidence rate was 1.3 cases per 100,000 population. The majority of cases were in men (male to female ratio 1.7:1), and most patients were aged in their third through seventh decades (82%). Outdoor occupations were noted for only 28.9% of cases. Cases occurred throughout the year with no significant seasonal peak. Although 55% saw a physician within 7 days of onset of illness, 29% presented after 1 month. Despite early presentation, diagnosis was often delayed for more than 1 month (43.3%). Single organs were involved in 82.8% of cases. For all cases, organ systems involved included lungs (91.4%), skin (18.1%), bone (4.3%), genitourinary system (1.8%), and central nervous system (1.2%). The presence of skin or bone disease was associated with multiorgan involvement. Thirty-three patients died (11.5%), 6 of whom received no therapy. Patients who died were significantly older than those who survived. A successful outcome without relapse was noted in 86.5% of amphotericin B-treated patients and in 81.7% of ketoconazole-treated patients. The relapse rate for ketoconazole-treated patients was higher than for amphotericin B-treated patients (14% and 3.9% respectively).

Adolescent↗
PubMed1996

Re-engineering a pharmacy work system and layout to facilitate patient counseling.

The development and evaluation of a new work system and facility design for a chain of community pharmacies are described. A new work system was developed to optimize utilization of pharmacist and technician time and allow the pharmacy to increase patient counseling without adding personnel. In the new system, pharmacists would review prescriptions, check technicians' work, and dispense prescriptions, counseling patients as needed; technicians would enter prescriptions into the pharmacy computer and fill them. The existing work system and design were evaluated in June and July of 1992 by observing, classifying, and recording activities of pharmacy personnel three days per week at six pharmacies in the chain. Pharmacy designs that would work with the new work system were created by a university design class after consultation with representatives of the pharmacy chain and the university's college of pharmacy. The pharmacy chain selected one design, and a detailed floor plan and specifications were created. To test how the new design and system would work at each of the six test pharmacies, a computer simulation program was developed and verified by using the data collected on the existing pharmacy operations. Computer simulation showed that, with the new design and system, increasing patient counseling would increase patient waiting time slightly but would not require additional personnel. The layout and work system in a chain of community pharmacies were redesigned to facilitate patient counseling and make the best use of employee time.

Community Pharmacy Services↗
PubMed1994

A modified free gracilis flap in the rat.

We present in this paper the use of a combined neurovascularized flap of gracilis muscle and inguinal skin in the rat with the femoral vessels and obturator nerve serving as the pedicles. The epigastric, saphenous, and muscular branch vessels arising from the femoral vessels were preserved, and a portion of adductor magnus muscle was included in the flap to protect the delicate muscle vessels at their origins. The inguinal skin and muscle flap both had independent blood supplies, thus separate assessment of muscle and skin rejection was possible in the single transplanted "packet." The muscle flap with the reconnected motor nerve regained contractile ability upon nerve stimulation within 30 days after the iso-transplantation. The results suggest that the modified gracilis myocutaneous flap provides an ideal model for transplantation research.

Animals↗
PubMed1992

Initiation of transcription by T7 RNA polymerase as its natural promoters.

A kinetic assay has been developed to measure the strength of natural T7 promoters. By determining the rate of appearance of initiation products in the presence of constant concentrations of T7 RNA polymerase, an incomplete mixture of ribonucleoside triphosphates, and increasing promoter concentrations, a maximum rate of product formation (Vmax) and a promoter concentration giving half of the maximal activity ([P]Vmax/2) can be determined for any cloned T7 promoter. On supercoiled plasmids, it was found that the [P]Vmax/2 measured for the six promoters phi 1.1B, phi 1.3, phi 3.8, phi 6.5, phi 10, and phi 13 ranged from 3.4 +/- 1.1 to 12.0 +/- 2.4 nM while the Vmax values showed no significant trends. On plasmids that had been linearized by cleavage at a single site with a restriction endonuclease, the cloned T7 promoters assayed fell into two broad classes that appear to be characterized by the T7 class II and III promoters. Generally, the class II promoters required higher promoter concentrations to produce half of the maximum rates of initiation ([P]Vmax/2 values) than the class III promoters. The [P]Vmax/2 values for the class II promoters ranged from 20 +/- 2.7 to 23 +/- 3.6 nM, while the [P]Vmax/2 values for the class III promoters phi 10 and phi 13 were 13 +/- 1.6 nM and 7.8 +/- 1.4 nM. The one exception is the class III promoter phi 6.5 whose [P] Vmax/2 (17 +/- 5 nM) falls between the [P]Vmax/2 values of the class II promoters and the strong class III promoters. The Vmax values measured on linear templates are variable, but it appears that phi 10 is more active than the other five promoters.

Adenosine Triphosphate↗
PubMed1992

Development of self-recognition in chimpanzees (Pan troglodytes).

Chimpanzees (Pan troglodytes) demonstrate the ability to recognize themselves in mirrors, yet investigations of the development of self-recognition in chimpanzees are sparse. Twelve young chimpanzees, grouped by age, were given mirror exposure and tested for self-recognition and contingent movement. All 6 juveniles, 4 and 5 years old, exhibited mirror-guided, mark-directed behavior and clear evidence of self-recognition. In contrast, among the infants, only the oldest group of 2 1/2-year-olds exhibited clear evidence of self-recognition. All chimpanzees exhibited both self-directed behaviors and contingent movements. These results suggest that self-recognition occurs at a slightly older age in chimpanzees than in human infants. In humans, self-recognition is linked with other cognitive abilities. The results conform to the general pattern that great apes exhibit many cognitive skills comparable to those of 2-year-old humans.

Affect↗
PubMed1992

Listerial infections in patients with systemic lupus erythematosus.

Infection with Listeria monocytogenes is known to occur more frequently in immunosuppressed patients, including those receiving high-dose prednisone or cytotoxic therapy for collagen vascular disease. We reviewed three cases of listeriosis and systemic lupus erythematosus (SLE) seen at our institution, in addition to five cases reported in the English literature. Seven of the eight patients had non-CNS listerial infections. All patients but one had associated risk factors of either renal failure or pregnancy. From our review, we found that listeriosis is uncommon in SLE, and patients without renal failure or pregnancy do not seem to be at increased risk for listeriosis. Although most patients were treated with high-dose prednisone, with or without cytotoxic drugs, the role of immunosuppression by these drugs as a risk factor for listeriosis remained unclear.

Adult↗
PubMed1992

[Preliminary study of cartilage repair with autologous periosteum and fibrin adhesive system].

The potential surgical transplantation with autogenous periosteal grafts and Fibrin Adhesive System (FAS) was attempted in a rabbit model. The grafts were taken from the tibia, transplanted and fixed with FAS to artificial full-thickness (0.4 x 0.3 cm) defect on the femoral condyle. Histologic and ultrastructural findings revealed chondrocyte regeneration in the control, grafted, and graft/FAS treated group at week 6; however, chondrogenesis of the reparative tissue was best demonstrated in the graft/FAS group. At week 12, the interface between the reparative tissue and the surrounding tissue was invisible in the FAS/graft group, as compared with the well-defined interface in the grafted group and the control. The results strongly suggest that FAS-treated periosteal transplant is a potential model for the repair of articular cartilage defects. Although the results are preliminary, all seem promising in the clinical aspects.

Animals↗
PubMed1991

Vascularized autogenous canine coccygeal bone transfer.

Based on cadaver studies in dogs, the 8th, 9th, or 10th canine coccygeal vertebra with overlying skin was designed for free vascularized bone transfer. In six dogs the coccygeal osteocutaneous flap was transferred to fill a defect of the tibia, anastomosing the median caudal artery and one of the two caudal veins to the tibial vessels. The overlying skin provided a reliable monitoring system for the transferred tissue. The behavior of the vascularized coccygeal vertebrae was then evaluated with radiographic and histologic examination and compared with control vertebrae transferred without reconnection of the blood vessels. The results revealed that the canine coccygeal bone graft is a reliable vascularized osteocutaneous flap, which can be applied either in clinical veterinary surgery or in orthopedic microsurgical research.

Anastomosis, Surgical↗
PubMed1990

Amphotericin B blunts erythropoietin response to anemia.

Amphotericin B causes a normochromic, normocytic anemia thought to be mediated by direct marrow toxicity or suppression of erythropoietin production. Serial hemoglobin, hematocrit, amphotericin B, and erythropoietin levels were determined before, during, and after completion of amphotericin B therapy for three patients without significant renal disease or active hematologic malignancy. Patients with systemic fungal diseases treated with itraconazole served as controls. Serum erythropoietin levels were determined by radioimmunoassay and amphotericin B by high-performance liquid chromatography. Despite anemia in all amphotericin B-treated patients, erythropoietin levels declined or remained relatively constant during therapy while erythropoietin levels in controls were appropriate for the degree of anemia. Within 2 weeks of completion of amphotericin B treatment, two patients had increasing erythropoietin levels in response to anemia. Amphotericin B appears to suppress but not abolish the erythropoietin response to anemia; this effect disappears quickly after discontinuation of the drug.

Amphotericin B↗
PubMed1988

Effects of simulated facility-design changes on outpatient pharmacy efficiency.

The potential effects of using the Baker drug counter or the Systamodule pharmacy fixture, or both, on the efficiency of the current outpatient pharmacy system at the National Institutes of Health were evaluated by computer simulation. It was hypothesized that the use of these two devices would reduce (1) the prescription-filling time (RxFT) and (2) the distance traveled (DT) by pharmacists in filling individual prescriptions. The sample used was 20% of two weeks' prescriptions, randomly selected. All theoretical estimations of RxFT were done by a computer program; DT was calculated based on measurements from the architect's schematic drawings. The effect of the application of the Baker drug counter alone, the Systamodule pharmacy fixture alone, and the Baker drug counter in combination with the Systamodule pharmacy fixture was to reduce the prescription-filling time by 0.123, 0.159, and 0.280 minutes per prescription, respectively. The average DT per prescription, 102 feet, was identical in the current NIH pharmacy and with use of the Baker counter. It was reduced by 86.3% (to 14 feet) with use of the Systamodule feature, both alone and in combination with the Baker counter. The use of the Baker drug counter and the Systamodule together promises improved efficiency of the prescription dispensing operation.

Computer Simulation↗
PubMed1987

Clonorchiasis: an update.

The ability of Clonorchis sinensis to cause severe hepatobiliary disease is illustrated by the case we have reported, in which biliary obstruction and hepatic fibrosis resulted from the pathologic process associated with chronic clonorchiasis. Immunodiagnostic tests are currently limited, and diagnosis, as illustrated by our case, relies on identification of the fluke, usually as the adult or egg stage in clinical specimens. Praziquantel has revolutionized therapy of this disease, but surgical drainage may be necessary to relieve biliary obstruction. Physicians caring for emigrants or travelers from the Clonorchis endemic belt need to be aware of the manifestations of clonorchiasis to enhance diagnosis and therapy.

Aged↗