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Biomedical subjects

F Y Lin

Publications and source records attributed to F Y Lin.

At least 55 records · Page 3Linked to original sources
PubMed1999

Regional differences in the recovery course of tachycardia-induced changes of atrial electrophysiological properties.

BACKGROUND: Regional differences in recovery of tachycardia-induced changes of atrial electrophysiological properties have not been well studied. METHODS AND RESULTS: In the control group (5 dogs), atrial effective refractory period (AERP) and inducibility of atrial fibrillation (AF) were assessed before and every 4 hours for 48 hours after complete atrioventricular junction (AVJ) ablation with 8-week VVI pacing. In experimental group 1 (15 dogs), AERP and inducibility of AF were assessed before and after complete AVJ ablation with 8-week rapid right atrial (RA) pacing (780 bpm) and VVI pacing. In experimental group 2 (7 dogs), AERP and inducibility of AF were assessed before and after 8-week rapid left atrial (LA) pacing and VVI pacing. AERP and inducibility and duration of AF were obtained from 7 epicardial sites. In the control group, atrial electrophysiological properties obtained immediately and during 48-hour measurements after pacing did not show any change. In the 2 experimental groups, recovery of atrial electrophysiological properties included a progressive recovery of AERP shortening, recovery of AERP maladaptation, and decrease of duration and episodes of reinduced AF. However, recovery of shortening and maladaptation of AERP and inducibility of AF was slower at the LA than at the RA and Bachmann's bundle. CONCLUSIONS: The LA had a slower recovery of tachycardia-induced changes of atrial electrophysiological properties, and this might play a critical role in initiation of AF.

Animals↗
PubMed1999

Oral urografin in postoperative small bowel obstruction.

The aim of our study was to determine whether Urografin has the potential to offer surgeons a way of differentiating complete from partial small bowel obstruction and whether partial small bowel obstruction can be treated nonoperatively. Altogether 116 patients who had postoperative small bowel obstructions without any toxic signs underwent Urografin studies. Urografin (40 ml) mixed with 40 ml of distilled water was administrated either orally or via nasogastric tube to each patient. Serial plain abdominal radiographs were taken 2, 4, and 8 hours later. A total of 74 patients (63.8%) whose contrast medium reached the colon within the first 8 hours were considered to have partial obstruction and were successfully treated with intravenous hydration and nasogastric decompression. The remaining 42 patients (36.2%) in whom the contrast medium failed to reach the colon within the first 8 hours were regarded as having complete obstruction, and 34 of those patients (81.0%) underwent surgery; 8 (19.0%) received conservative treatment. Adhesion bands with complete bowel obstruction were observed in all 34 patients (100.0%) during laparotomy. Regardless of the presence of an air-fluid level on a plain abdominal radiograph or abdominal pain, a liquid diet followed by a soft diet could be given to those patients whose Urografin emptied into the colon. All the patients with partial bowel obstruction were treated successfully with nonoperative methods. The presence of Urografin in the colon within 8 hours of ingestion as an indicator for nonoperative treatment had a sensitivity of 90.2%, a specificity of 100%, and an accuracy of 93. 1%. Urografin, a safe and reliable water-soluble contrast medium, can be used to differentiate partial intestinal obstruction from complete intestinal obstruction. Early oral intake was found to be a major advantage of Urografin use in this study, and the potential of Urografin use to shorten the period of conservative treatment for postoperative small bowel obstruction needs further investigation.

Administration, Oral↗
PubMed1999

Rescue for acute myocarditis with shock by extracorporeal membrane oxygenation.

BACKGROUND: Acute myocarditis (AM) complicated with refractory cardiogenic shock carries a very high mortality. We report our experience in treating these patients, who were rescued by extracorporeal membrane oxygenation (ECMO) and intravenous immunoglobulin. METHODS: Over a 5-year period, 5 patients with AM were rescued with ECMO in our hospital. Femoral venoarterial ECMO was performed in 4 patients, and right atrium-left atrium-aorta ECMO in the other 1 due to ventricular dysfunction. Hemofiltration was applied to 3 patients. Marked elevated creatine kinase, its MB form, and troponin T (TnT) were found before ECMO. RESULTS: All the patients could be weaned off the ECMO after 140.0+/-57.7 hours of ECMO support. One patient died of multiple organ failure 10 days later after removal of ECMO, resulting in a 20% mortality. Renal function returned to normal in all survivors. The 4 survivors were discharged uneventfully in 23.3+/-8.3 days and resumed functional class I status. The TnT level declined to the low level within 3 days (slope -4.94+/-1.18 ng/mL/day), and might be an indicator of good recovery of myocardium. CONCLUSIONS: ECMO can provide an effective and simple treatment for critical AM with a satisfactory result and reduce the possibility of progressive cardiomyopathy.

Acute Disease↗
PubMed1999

Down-regulation of L-type calcium channel and sarcoplasmic reticular Ca(2+)-ATPase mRNA in human atrial fibrillation without significant change in the mRNA of ryanodine receptor, calsequestrin and phospholamban: an insight into the mechanism of atrial electrical remodeling.

OBJECTIVES: We investigated the gene expression of calcium-handling genes including L-type calcium channel, sarcoplasmic reticular calcium adenosine triphosphatase (Ca(2+)-ATPase), ryanodine receptor, calsequestrin and phospholamban in human atrial fibrillation. BACKGROUND: Recent studies have demonstrated that atrial electrical remodeling in atrial fibrillation is associated with intracellular calcium overload. However, the changes of calcium-handling proteins remain unclear. METHODS: A total of 34 patients undergoing open heart surgery were included. Atrial tissue was obtained from the right atrial free wall, right atrial appendage, left atrial free wall and left atrial appendage, respectively. The messenger ribonucleic acid (mRNA) amount of the genes was measured by reverse transcription-polymerase chain reaction and normalized to the mRNA levels of glyceraldehyde 3-phosphate dehydrogenase. RESULTS: The mRNA of L-type calcium channel and of Ca(2+)-ATPase was significantly decreased in patients with persistent atrial fibrillation for more than 3 months (0.36+/-0.26 vs. 0.90+/-0.88 for L-type calcium channel; 0.69+/-0.42 vs. 1.21+/-0.68 for Ca(2+)-ATPase; both p < 0.05, all data in arbitrary unit). We further demonstrated that there was no spatial dispersion of the gene expression among the four atrial tissue sampling sites. Age, gender and underlying cardiac disease had no significant effects on the gene expression. In contrast, the mRNA levels of ryanodine receptor, calsequestrin and phospholamban showed no significant change in atrial fibrillation. CONCLUSIONS: L-type calcium channel and the sarcoplasmic reticular Ca(2+)-ATPase gene were down-regulated in atrial fibrillation. These changes may be a consequence of, as well as a contributory factor for, atrial fibrillation.

Adolescent↗
PubMed1999

Subcutaneous emphysema and pneumomediastinum after dental extraction.

Pneumomediastinum, pneumothorax, and subcutaneous emphysema can occur occasionally after a surgical procedure. Facial swelling is a common complication of dental management. The occurrence of subcutaneous emphysema, pneumothorax, and pneumomediastinum after dental procedures is rare. We present a case with subcutaneous emphysema of the upper chest, neck, chin, and pneumomediastinum after a tooth extraction and discuss the possible mechanism of subcutaneous emphysema. To prevent these complications during dental procedures, dental hand pieces that have air coolant and turbines that exhaust air in the surgical field should not be used.

Adult↗
PubMed1999

Body region prevalence of injury in alcohol- and non-alcohol-related traffic injuries.

OBJECTIVE: To explore the relationship between alcohol use and body region of injury in patients injured in traffic collisions. MATERIALS AND METHODS: A prospective study of 381 patients involved in traffic collisions over the past 4 months. These patients were categorized as either using alcohol or not using alcohol on the day of the accident. Eighty of 381 patients (21%) had detectable blood alcohol concentrations. Age, sex, location of injury, helmet use, clinical diagnosis, Injury Severity Score, Glasgow Coma Scale score, and blood alcohol concentrations were collected for each patient. Blood alcohol concentrations were measured by the radioactive energy attenuation method. RESULTS: The incidence of head, face, chest, abdomen, and extremity injury in patients with alcohol use was 39%, 56%, 13%, 15%, and 55%, respectively, and 26%, 32%, 15%, 12%, and 63% in those without alcohol use, respectively. The differences in the incidence of head and facial injuries were significant between these two groups (p<0.05). Mean blood alcohol concentrations in head, face, chest, abdomen, and extremity injury were 171, 204, 215, 231, and 163 mg/dL, respectively. CONCLUSION: More injuries to the head and facial areas compared with other body parts were found in patients with alcohol use. However, alcohol level did not seem to influence the region of the body injured.

Accidents, Traffic↗
PubMed1999

Impaired cardiac performance relating to delayed left atrial activation after atrial compartment operation for chronic atrial fibrillation.

In the presence of a normal atrial systole and optimal AV delay, atrial kick contributes to a significant fraction of the stroke volume. This atrial contribution may be lost during atrial asystole or mismatch in the timing of atrial and ventricular contraction. A patient received atrial compartment operation for his chronic AF. Although the AF was successfully converted to sinus rhythm, the conduction from the right to left atrium was markedly delayed so that the left atrial and ventricular activations occurred almost simultaneously. This delay in left atrial activation resulted in impaired cardiac performance.

Atrial Fibrillation↗
PubMed1999

Change of atrial refractory period after short duration of rapid atrial pacing: regional differences and possible mechanisms.

It is unknown whether there are regional differences in the change of atrial effective refractory period (ERP) after a short duration of rapid atrial pacing. Furthermore, the effects of calcium channel and potassium channel on this phenomenon have not been extensively investigated. In opened-chest dogs, the endocardial monophasic action potential duration at 90% repolarization (APD90) from the right atrial appendage, and ERP from seven atrial sites were measured before and after rapid atrial pacing at 800 beats/min for 30 minutes. Both atrial ERP and APD90 significantly shortened after rapid atrial pacing. The postpacing atrial ERP and APD90 shortening persisted for 119 +/- 3 and 123 +/- 4 seconds after cessation of pacing, respectively. There was no significant difference in the magnitude or recovery course of atrial ERP shortening after pacing among the seven atrial sites. Pretreatment with nicorandil and d-sotalol had no effects on the magnitude or recovery course of atrial ERP shortening after pacing. However, the degree of ERP and APD90 shortening after pacing was significantly attenuated in the verapamil and ryanodine groups; furthermore, the recovery of ERP and APD90 after cessation of pacing was faster in the two groups. In conclusion, shortening of atrial ERP induced by short-duration rapid atrial pacing was uniform in both atria. Both the adenosine triphosphatase (ATP) dependent potassium current and rapid component of the delayed rectifier did not significantly influence this phenomenon, but both the verapamil and ryanodine could significantly attenuate the degree of atrial ERP and APD90 shortening.

Adenosine Triphosphatases↗
PubMed1999

Measurement of funny current (I(f)) channel mRNA in human atrial tissue: correlation with left atrial filling pressure and atrial fibrillation.

INTRODUCTION: The funny current (I(f)) contributes to phase IV spontaneous depolarization in cardiac pacemaker tissue. Enhanced I(f) activity in myocardial tissue may lead to increased automaticity and therefore tachyarrhythmia. We measured the amount of I(f) activity in the messenger ribonucleic acid (mRNA) in human atrial tissue and correlated the mRNA amount to left atrial filling pressure and atrial fibrillation (AF). METHODS AND RESULTS: A total of 34 patients undergoing open heart surgery were included (15 men and 19 women, aged 55+/-10 years). Atrial tissue was obtained from the right atrial free wall, the right atrial appendage, the left atrial free wall, and the left atrial appendage, respectively. The mRNA amount of the I(f) channel was measured by reverse transcription polymerase chain reaction and was normalized to the mRNA levels of glyceraldehyde 3-phosphate dehydrogenase. We found that the I(f) channel mRNA was present at all the atrial sampling sites. A higher left atrial filling pressure, an indicator of congestive heart failure, was associated with a higher I(f) mRNA level (r2 = 0.446, P < 0.01 by linear regression). We also found that the mRNA amount was significantly higher in patients with AF than in patients without AF (1.68+/-0.49 vs 1.27+/-0.43; P < 0.05). Age, sex, right atrial filling pressure, left atrial dimension, and left ventricular ejection fraction had no significant effect on the mRNA level. CONCLUSION: The mRNA of the I(f) channel is present in the free-wall area and appendage area from both atria. Increased left atrial filling pressure and clinical AF are associated with increased I(f) mRNA level.

Adolescent↗
PubMed1999

Safety and immunogenicity of Vi conjugate vaccines for typhoid fever in adults, teenagers, and 2- to 4-year-old children in Vietnam.

The capsular polysaccharide of Salmonella typhi, Vi, is an essential virulence factor and a protective vaccine for people older than 5 years. The safety and immunogenicity of two investigational Vi conjugate vaccines were evaluated in adults, 5- to 14-year-old children, and 2- to 4-year-old children in Vietnam. The conjugates were prepared with Pseudomonas aeruginosa recombinant exoprotein A (rEPA) as the carrier, using either N-succinimidyl-3-(2-pyridyldithio)-propionate (SPDP; Vi-rEPA(1)) or adipic acid dihydrazide (ADH; Vi-rEPA(2)) as linkers. None of the recipients experienced a temperature of >38.5 degrees C or significant local reactions. One injection of Vi-rEPA(2) into adults elicited a geometric mean (GM) increase in anti-Vi immunoglobulin G (IgG) from 9.62 enzyme-linked immunosorbent assay units/ml (EU) to 465 EU at 6 weeks; this level fell to 119 EU after 26 weeks. In the 5- to 14-year-old children, anti-Vi IgG levels at 6 weeks elicited by Vi-rEPA(2), Vi-rEPA(1), and Vi were 169, 22.8, and 18.9 EU, respectively (P = 0.0001 for Vi-rEPA(1) and Vi with respect to Vi-rEPA(2)). At 26 weeks, the anti-Vi IgG levels for recipients of Vi-rEPA(2), Vi-rEPA(1), and Vi were 30.0, 10.8, and 13.4 EU, respectively (P < 0.001 for Vi-rEPA(1) and Vi with respect to Vi-rEPA(2)); all were higher than the preinjection levels (P = 0. 0001). Vi-rEPA(2) also elicited the highest anti-Vi IgM and IgA levels of the three vaccines. In the 2- to 4-year-old children at 6 weeks following the first injection, Vi-rEPA(2) elicited an anti-Vi IgG level of 69.9 EU compared to 28.9 EU for Vi-rEPA(1) (P = 0.0001). Reinjection increased Vi antibody levels from 69.9 to 95.4 EU for Vi-rEPA(2) and from 28.9 to 83.0 EU for Vi-rEPA(1). At 26 weeks, anti-Vi IgG levels remained higher than those at preinjection (30.6 versus 0.18 for Vi-rEPA(2) and 12.8 versus 0.33 for Vi-rEPA(1); P = 0.0001 for both). Vi vaccine is recommended for individuals of 5 years of age or older. In the present study, the GM level of anti-Vi IgG elicited by two injections of Vi-rEPA(2) in the 2- to 4-year-old children was higher than that elicited by Vi in the 5- to 14-year-old children (30.6 versus 13.4; P = 0.0001). The safety and immunogenicity of the Vi-rEPA(2) conjugate warrant further investigation.

ADP Ribose Transferases↗
PubMed1999

Changes in the mRNA levels of delayed rectifier potassium channels in human atrial fibrillation.

INTRODUCTION: We measured mRNA levels of delayed rectifier potassium channels in human atrial tissue to investigate the mechanism of the shortening of the atrial effective refractory period and the loss of rate-adaptive shortening of the atrial effective refractory period in human atrial fibrillation. METHODS AND RESULTS: A total of 34 patients undergoing open heart surgery were included. Atrial tissue was obtained from the right atrial free wall, right atrial appendage, left atrial free wall and left atrial appendage, respectively. The mRNA amounts of KVLQT1 (IKs), minK (beta-subunit of IKs), HERG (IKr), and KV1.5 (IKur) were measured by reverse transcription-polymerase chain reaction and normalized to the mRNA amount of GAPDH. We found that the mRNA levels of KV1.5, HERG and KVLQT1 were all significantly decreased in patients with persistent atrial fibrillation for more than 3 months. In contrast, the mRNA level of minK was significantly increased in patients with persistent atrial fibrillation for more than 3 months. We further showed that these changes were independent of the underlying cardiac disease, atrial filling pressure, gender and age. We also found that there was no spatial dispersion of mRNA levels among the four atrial sampling sites. CONCLUSIONS: Because the decrease in potassium currents results in a prolonged action potential, the shortening of the atrial effective refractory period in atrial fibrillation should be attributed to other factors. However, the decrease in IKs might contribute, at least in part, to the loss of rate-adaptive shortening of the atrial refractory period.

Adolescent↗
PubMed1999

Postoperative short-term sedation with propofol in cardiac surgery.

We conducted a randomized double-blind study to assess the safety and effectiveness of short-term sedation with propofol in adult patients immediately after cardiac surgery. Sixty hemodynamically stable adult patients who underwent cardiac surgery were randomly assigned to receive propofol postoperatively or no postoperative sedation. The propofol group (n = 30) received propofol infusion (1 mg.kg-1.hr-1) immediately after they awoke postoperatively. The infusion rates were adjusted to maintain a sedation level (Ramsay score) of 3. Nurses assessed the effectiveness of the sedation according to Ramsay scores; the patients also subjectively evaluated sedation. Postoperative pulmonary oxygenation dysfunction (PaO2/FiO2 < 300 mm Hg) was noted in 10 patients receiving propofol and in eight patients in the control group. The dysfunction was greatly improved after overnight ventilator support, and this improvement was not affected by propofol sedation. The propofol group received an average of 13.6 +/- 5.3 hours of propofol infusion, at an average infusion rate of 0.96 +/- 0.16 mg.kg-1.hr-1. Patients receiving propofol remained well sedated (Ramsay score > or = 2) during 99.3% of the study period, while the control patients remained anxious or agitated (Ramsay score, 1) during 12% of the study period. Patients receiving propofol were successfully extubated 9 +/- 4 minutes after cessation of propofol infusion, without complications. The turnover of intensive care unit beds was not delayed by propofol sedation. Subjective evaluations (scored on an analog scale: 0 = nil, 10 = extreme) revealed that patients receiving propofol felt less pain than those in the control group (2.3 +/- 2.7 vs 4.7 +/- 3.1, p < 0.05), had better sleep quality (7.8 +/- 2.9 vs 5.1 +/- 2.9, p < 0.05), and were more satisfied with the care they received (8.3 +/- 2.2 vs 5.8 +/- 3.9, p < 0.05). These findings suggest that propofol infusion is effective for short-term sedation of cardiac surgery patients postoperatively and that an infusion rate adequate to maintain a Ramsay score of 3 may be ideal. Postoperative sedation should be considered for all cardiac surgery patients, not only those with outward signs of anxiety or agitation.

Cardiac Surgical Procedures↗
PubMed1998

Advanced field-measurement method with three orthogonal Hall probes for an elliptically polarizing undulator.

A three-orthogonal-Hall-probe assembly with an 'on the fly' mapping method has been developed to characterize an elliptically polarizing undulator (EPU). The underlying design concept is that it can measure the three real field components without any field correction under a reliable and synchronization measurement method. Therefore, the relative central position shift, orthogonal angle and the planar Hall effect error between the three Hall probes should be calibrated and readjusted. Experimental results demonstrate that this method can yield an r.m.s. reproducibility of 10 G cm for the three field components and 2 G for the peak field strength. Under precision conditions this system can completely measure the three on-axis field components within 2 min for a 4 m-long EPU.

Journal Article↗
PubMed1998

An SRRC elliptically polarizing undulator prototype to examine mechanical design feasibility and magnetic field performance.

In this work, a 1 m long Sasaki-type elliptically polarizing undulator (EPU) prototype with 5.6 cm period length is used to examine the mechanical design feasibility as well as magnetic field performance. The magnetic field characteristics of the EPU5.6 prototype at various phase shifts and gap motion are described. The field errors from mechanical tolerances, magnet block errors, end field effects and phase/gap motion effects are analysed. The procedures related to correcting the field with the block position tuning, iron shimming and the trim blocks at both ends are outlined.

Journal Article↗
PubMed1998

Antibiotic susceptibility profile of group B streptococcus acquired vertically.

OBJECTIVE: To determine the contemporary antibiotic susceptibility profile of vertically acquired group B streptococcal isolates. METHODS: Susceptibility to ampicillin, penicillin G, erythromycin, clindamycin, cefazolin, and gentamicin was assessed by two methods, minimal inhibitory concentration and disc diffusion. RESULTS: The susceptibility profiles of 119 colonizing and eight invasive strains of group B streptococcus isolated from January 1996 to September 1997 at two hospitals in Birmingham, Alabama-University of Alabama at Birmingham and Cooper Green-were studied. Minimal inhibitory concentration determinations indicated that all colonizing strains were susceptible or moderately susceptible to ampicillin and penicillin G. Resistance was noted by at least one strain to each of the other antibiotics; all were resistant to gentamicin, whereas 27 (21%) were resistant to erythromycin, five (4%) to clindamycin, and one (1%) to cefazolin. All of the eight invasive strains were susceptible or moderately susceptible to ampicillin, penicillin G, clindamycin, and cefazolin; one (13%) was resistant to erythromycin, and all were resistant to gentamicin. Disc diffusion results generally were concordant with minimal inhibitory concentration results, although by disc diffusion fewer isolates were classified as susceptible, and more as moderately susceptible, to ampicillin and penicillin G than by minimal inhibitory concentration. CONCLUSION: Universal susceptibility of group B streptococcus to members of the penicillin family supports the continued use of penicillin G or ampicillin for early onset neonatal group B streptococcal disease prevention. For patients allergic to beta-lactam agents, clindamycin (4% resistance) may be a better alternative than erythromycin (21% resistance).

Anti-Bacterial Agents↗
PubMed1998

Water-soluble contrast study predicts the need for early surgery in adhesive small bowel obstruction.

BACKGROUND: The optimal period of conservative treatment for adhesive small bowel obstruction remains controversial. This study sought to determine whether a 24-h abdominal radiograph after oral Urografin is a reliable indicator for operation in patients with adhesive small bowel obstruction. METHODS: One hundred and sixty-one patients who suffered from adhesive intestinal obstruction without clinical evidence of strangulation or gangrene underwent a Urografin study. Some 40 ml Urografin mixed with 40 ml distilled water was administered either orally or via a nasogastric tube to each patient. Serial plain abdominal radiographs were taken 4, 8, 16 and 24 h later. If an earlier plain radiograph showed that contrast medium had reached the ascending colon, subsequent radiographs were not taken. RESULTS: Contrast medium reached the colon within 24 h in 112 patients (70 per cent). These patients were all treated successfully with non-operative methods. Contrast medium was not observed in the colon within the first 24 h in 49 patients (30 per cent). Operation was performed in 47 of these patients and non-operative treatment was given in two. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of Urografin reaching the colon within 24 h as an indicator for non-operative treatment were 98, 100, 99, 100 and 96 per cent respectively. CONCLUSION: All patients with evidence of Urografin reaching the colon within 24 h were treated successfully with non-operative methods. The results of this prospective study suggest that patients with adhesive intestinal obstruction in whom contrast medium fails to reach the colon within 24 h should receive prompt surgical intervention.

Adult↗