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Biomedical subjects

C L Lee

Publications and source records attributed to C L Lee.

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

Developmental neuroplasticity: roles in early life seizures and chronic epilepsy.

Both clinical and experimental studies suggest that the immature nervous system is unusually susceptible to seizures during critical periods in postnatal life. A late onset of gamma-aminobutyric acid (GABA)-mediated synaptic inhibition could conceivably play a contributing role in this phenomenon. Numerous studies have shown that neural systems that use GABA in the neonatal brain are different than those of adulthood. GABA is an excitatory neurotransmitter that likely plays a neurotrophic role in neuronal differentiation. Other reports suggest that unique, possibly transient, GABAergic interneuron populations exist in the embryonic and neonatal nervous system. At these early times in development, the immature nervous system is remarkably resistant to seizure generation. However, as the hippocampus and neocortex enter the critical period of enhanced seizure susceptibility, inhibitory GABA systems mature rapidly. At this time, blockade of GABA type A (GABAA) receptors produce unusually severe seizure discharges. In hippocampus, concurrent exuberant outgrowth of recurrent excitatory axon collaterals and synapses appear to play a role in the generation of these seizures. As the hippocampus matures, these axons are morphologically remodeled and nearly 50% of branches within arbors are pruned. This pruning of axon branches corresponds in time with the decrease in seizure susceptibility that characterizes adulthood. Developmental remodeling of neuronal connectivity is a common feature of most areas of the central nervous system. Results from an audiogenic seizure model of early onset epilepsy suggest that prevention of axon arbor remodeling by transient sensory deprivation can lead to a permanent overinnervation of target nuclei and chronic seizure susceptibility. Early life seizures may have a similar effect. Recent results in one model have shown that repeated seizures induced by intrahippocampal injections of tetanus toxin during a critical period results in a chronic epilepsy. Future studies should attempt to determine if the synchronized discharging of early-life seizures prevents the remodeling of neuronal connectivity that normally takes place during postnatal development and results in an overinnervated and chronically hyperexcitable hippocampus.

Aging↗
PubMed1999

[Relatedness of Shigella sonnei isolates from six outbreaks in Tao-Yuan area, Taiwan].

Between November 1995 and January 1996, one larger-scale outbreak of Shigella sonnei infection occurred in the area of Tao-Yuan, Taiwan. Subsequently, five outbreaks of S. sonnei infection occurred in the same area during the period from October 1998 to February 1999. Fifty-five isolates obtained from these six outbreaks were differentiated by antimicrobial susceptibility testing, plasmid profile analysis (PPA) and pulsed-field gel electrophoresis (PFGE). They were classified into two and three types by antimicrobial susceptibility testing and PPA, respectively. However, only one pattern was observed by PFGE. The molecular epidemiology by PFGE in this study indicated that they were closely-related. These data suggest that the clinical isolates obtained during the period of January 1998 to January 1999 were probably derived from the outbreak strain of 1995.

Disease Outbreaks↗
PubMed1999

A huge 6.2 kilogram uterine myoma coinciding with omental leiomyosarcoma: case report.

Surgery for massive abdominal tumors is both interesting and challenging. We present a case involving a multiple uterine myoma weighing 6.2 Kg which coincided with omental leiomyosarcoma. To our knowledge, this is the first report of this type of condition in the English literature. A 44-year-old nulliparous woman had suffered from abdominal pain for a long time. A huge abdominal mass was palpated on physical examination. Computed tomography scanning revealed a huge pelvic-abdominal mass with the possibility of small bowel loops invaded by the mass. A 6-cm omental mass was incidentally found during the subsequent hysterectomy procedure. Perforation of the urinary bladder occurred during the dissection of adhesion. Resection of the omental mass, wide wedge resection of the invaded small bowel, primary repair of the bladder, and hysterectomy were performed. The final pathologic diagnosis was uterine leiomyomata with omental leiomyosarcoma. The patient returned home on postoperative day 14 and was well at the 18-month follow-up examination. The challenge of these tumors lies in their proper diagnosis and surgical management. More case reports and follow-up studies are needed to confirm the efficacy of their management.

Adult↗
PubMed1998

Spine loss and other persistent alterations of hippocampal pyramidal cell dendrites in a model of early-onset epilepsy.

To explore the anatomical substrates for network hyperexcitability in adult rats that become chronically epileptic after recurrent seizures in infancy, the dendritic and axonal arbors of biocytin-filled hippocampal pyramidal cells were reconstructed. On postnatal day 10, tetanus toxin was unilaterally injected into the hippocampus and produced brief but recurrent seizures for 1 week. Later, hippocampal slices taken from these rats exhibited synchronized network bursts in area CA3C. Both the apical and basilar dendritic arbors of CA3C pyramidal cells were markedly abnormal in these epileptic rats. There was a considerable reduction in the density of dendrite spines, although the extent of this loss could vary among dendritic segments. Spine density on terminal segments of the basilar and apical dendrites was reduced on average by 35 and 20%, respectively. In addition, the diameters of these same dendritic segments were markedly reduced. Dendritic spine loss has previously been suggested to indicate a partial deafferentation of epileptic neurons, but this interpretation is difficult to reconcile with the critical role recurrent excitatory synaptic transmission plays in the generation of synchronized network burst. In this study, axonal arbors of CA3C pyramidal cells exhibited normal branching patterns, branching complexity, and varicosity density. This suggests that if deafferentation occurs, synapses other than recurrent excitatory ones are lost. The morphological abnormalities reported here would be expected to significantly alter electrical signaling within dendrites that may contribute importantly to seizures and other behavioral sequelae of early-onset epilepsy.

Action Potentials↗
PubMed1998

Dye incorporation to enhance the laser ablation of standard and reduced-modulus bone cements.

Laser ablation of acrylic bone cement is an alternative method of cement removal that can be used during revision arthroplasty of cemented implants. This study investigated the feasibility of using a continuous-wave Argon ion laser (wavelength = 514 nm) with the addition of methylene blue or red dye no. 13 to enhance the ablation of two types of bone cements: polymethylmethacrylate and polybutylmethylmethacrylate. Six cement/dye combinations were studied while power (0.5, 0.75, and 1.0 W) and exposure times (30, 45, 60, and 90 seconds) were varied. The Argon laser was unable to ablate undyed polymethylmethacrylate or polybutylmethylmethacrylate. However, ablation was shown for both cements with either dye. The red dye had a stronger absorption peak at 514 nm than did the blue dye. Statistically larger ablation areas were seen for red polymethylmethacrylate than for blue polymethylmethacrylate (p < 0.013) at all levels tested. Ablation areas were larger in red than in blue polybutylmethylmethacrylate cement. Blue polybutylmethylmethacrylate cement produced larger ablation areas than did blue polymethylmethacrylate cements at all energy levels tested, with smaller surrounding damage areas. Red polybutylmethylmethacrylate cement also produced larger ablation areas than did red polymethylmethacrylate cement (at 0.75 and 1.0 W), again with smaller damage areas. Damage zones were smallest in red polybutylmethylmethacrylate cements at all test levels. These results suggest that, by using dyes to selectively alter the absorption characteristics of bone cement, laser ablation can be an effective method for cement removal. Changes in the chemical structure of the cement can also influence the response to laser treatment. Furthermore, the absorption spectra of the bone cement can be altered to maximize energy absorption at a wavelength that is not absorbed by bone tissue; this potentially minimizes damage to bone during revision surgery.

Arthroplasty↗
PubMed1998

Survival and distribution pattern of childhood liver cancer in Taiwan.

Studies of survival and distribution of liver cancer in children are scarce. In this study, using data from the cancer registry of Taiwan, from 1979 to 1992, we identified 377 young patients (0-15 years of age) suffering from liver cancer, coded 155 according to the International Classification of Diseases. Among these patients, 122 were histopathologically proven hepatocellular carcinoma (HCC) and 43 hepatoblastoma (HB). For survival analysis, we also searched for cases of liver cancer in 0-16 year old children in the Taiwan cancer registry for the period between 1988 and 1992. We found 109 cases with identification numbers and birth dates which allowed our cases to be linked with the death registry of the National Health Department of Taiwan enabling the calculation of 5-year survival rates using actuarial life tables. Between 1979 and 1992, for 122 HCC cases, there was a peak incidence at the age of 1 year, then a decline to a trough at the age of 4 years, after which the number of cases increased to the age of 15 years. After the age of 4 years boys outnumbered the girls by 2:1. 36 (84%) of 43 HB cases were under the age of 5 years and boys tended to outnumber girls by 2.9:1. Between 1988 and 1992, of the 109 patients, 49 were diagnosed histopathologically and 60 patients clinically. Their overall 5-year survival rate was 19%. The 5-year survival rate of the 28 HCC patients was 17%, whereas that of the 17 HB patients was 47%. In conclusion, our epidemiological findings indicate that the HCC distribution among children is different according to age and to some extent sex. The overall 5-year survival rate of children suffering from liver cancer was still unfavourable.

Adolescent↗
PubMed1998

Local circuit abnormalities in chronically epileptic rats after intrahippocampal tetanus toxin injection in infancy.

In vitro slice experiments were undertaken in adult rats to investigate the physiological origins of a chronic epileptic condition that was initiated in infancy. A unilateral injection of a minute quantity of tetanus toxin into hippocampus on postnatal day 10 produced a severe convulsive syndrome characterized by brief but repeated seizures that lasted for 5-7 days. Hippocampal slices were then taken from these rats in adulthood because at this time previous studies have shown the occurrence of electrographic and behavioral seizures. Dramatic alterations in local circuit functioning were observed. In normal artificial cerebrospinal fluid (ACSF), spontaneous epileptiform network bursts were recorded in a majority (73%) of experimental rats. Network bursts occurred in area CA3 of both the injected and contralateral hippocampus. These consisted of intracellular depolarization shifts that were coincident with extracellularly recorded network bursts. Often they occurred at frequencies of 0.05-0.1 Hz and although variable in amplitude and duration, had all-or-none-like qualities. These events appeared to arise largely from local circuits in the CA3C subfield. Network bursts were rarely recorded in area CA1 and were never observed in the dentate gyrus. However in 31% of rats, a novel, higher frequency (2-8 Hz) field potential was recorded in area CA1. This was coincident with rhythmic, intracellularly recorded, inhibitory postsynaptic potentials (IPSPs). These summated IPSPs blocked action potential firing and reversed polarity near -75 mV. To understand the origins of network bursting in area CA3C, comparisons were made of the fundamental neurophysiological properties of pyramidal cells in epileptic and control rats. Of the passive and active membrane properties examined, all appeared normal. Unusually prolonged bursts of action potentials were observed in a small subset of pyramidal cells. However on average the duration of intrinsic bursts were unaltered in the CA3 neurons analyzed from experimental rats. To explore the role that alterations in CA3 recurrent excitatory network excitability may play in epileptiform discharges, picrotoxin was bath applied. On blockade of gamma-aminobutyric acid (GABAA) receptors, slices from experimental rats underwent prolonged electrographic seizures that were up to 10 s in duration. In contrast, slices from control rats produced only brief 100-ms network bursts. These results suggest that a change in excitability within CA3C recurrent excitatory networks likely contributes to seizures in chronically epileptic rats. However, at the same time, this hyperexcitability is controlled to an important degree by functional GABAA-mediated synaptic inhibition.

Action Potentials↗
PubMed1998

The relationship between low back discomfort ratings and the NIOSH lifting index.

An epidemiological study was performed to evaluate the relation between low-back discomfort ratings and use of the revised NIOSH lifting guide to assess the risk of manual material handling (MMH) tasks. We surveyed 97 MMH workers on site in 15 factories and designed a questionnaire to systematically collect job-related information. Approximately 90% of the workers had suffered various degrees of lower back discomfort, and 80% had sought medical treatment. The survey showed that 42 of the 97 jobs analyzed had a recommended weight limit of 0, which was attributed to either a horizontal distance or a lifting frequency that exceeded the bounds of the NIOSH lifting index. Apparently, the limits for horizontal distance and maximum allowable frequency are too stringent to accommodate many existing MMH jobs. For the remaining 55 jobs, the significant positive correlation obtained between the lifting index and the severity of low-back discomfort suggests that the lifting index is reliable in assessing the potential risk of low-back injury in MMH. These findings provide useful information on the application of the NIOSH lifting guide to the assessment of low-back pain.

Adolescent↗
PubMed1998

Management of major complications in laparoscopically assisted vaginal hysterectomy.

We reviewed 722 laparoscopically assisted vaginal hysterectomies performed between March 1991 and March 1996 at our institute, looking at the management of major complications. The indications for hysterectomy included adenomyosis, myoma uteri, intractable menorrhagia, endometriosis, and severe pelvic adhesion. During 1 to 6 years' follow-up, there were 12 (1.7%) major complications, comprising six bladder injuries, one iliac artery perforation, two bowel injuries, two cases of partial intestinal obstruction, and one pelvic abscess. Four complications were repaired successfully by laparotomy, six were repaired laparoscopically or vaginally, and two were treated conservatively. All the cases with visceral injuries were detected intraoperatively, therefore, adequate repair operations could be performed uneventfully. Early detection and treatment allow complications to be resolved more easily.

Adult↗
PubMed1998

Pregnancy in a previous cesarean section scar: case report.

An ectopic pregnancy developing in a previous cesarean section scar is an extreme rarity among all ectopic pregnancies. Due to the difficulty of making an accurate diagnosis, this kind of ectopic pregnancy is the most dangerous and life-threatening type. A 30-year-old woman, who was gravida 4, para 3, was admitted to our emergency room with massive vaginal bleeding. She had undergone a cesarean section due to a breech birth 3 months prior to this admission. Ultrasound examination showed a pregnancy located in the low corpus uterus. The possibility of a spontaneous abortion in progress or a cervico-isthmic pregnancy were considered. Due to the massive vaginal bleeding and unstable vital signs of the patient, surgical intervention was decided upon to save the woman's life. We first performed dilatation and curettage. There was no gestational villi and severe vaginal bleeding was noted during this procedure. An emergent exploratory laparotomy was then performed, followed finally by a hysterectomy. Pathologic findings confirmed the diagnosis of a pregnancy in the previous cesarean section scar. Diagnosis, prevention, clinical evaluation and management of these conditions are discussed.

Adult↗
PubMed1998

One-week low-dose triple therapy is effective in treating Helicobacter pylori-infected patients with bleeding peptic ulcers.

Proton pump inhibitor (PPI)-based triple therapy, which combines a PPI and two antibiotics, is highly effective in eradicating Helicobacter pylori infection in peptic ulcer patients, even if given for only 1 week. However, the application of this regimen in patients with bleeding ulcers has not been adequately investigated. We studied the effectiveness of triple therapy in treating 122 patients with proven H. pylori infection, and bleeding stigmata on endoscopy; 97 had duodenal ulcer (DU), 15 had gastric ulcer (GU), and 10 had both types of ulcers. A regimen of omeprazole (20 mg), metronidazole (500 mg), and clarithromycin (250 mg) twice daily was administered for 1 week as soon as the patient could eat normally after bleeding, followed by omeprazole (20 mg) daily for 3 additional weeks. Follow-up endoscopy and 13C-urea breath tests (UBTs) were performed at least 4 weeks after triple therapy. A total of 104 patients completed the study, 83 with DU, 12 with GU, and nine with both. The overall ulcer healing rate was 97.1% and the eradication rate was 91.3%. Patients with and without H. pylori eradication did not differ significantly in terms of age, gender, UBT titer, units of blood transfused, or interval between endoscopy and the beginning of triple therapy. We conclude that 1-week low-dose PPI-based triple therapy is effective in eradicating H. pylori infection in patients with bleeding peptic ulcers. When followed by 3 weeks of additional PPI treatment, a satisfactory ulcer healing rate can also be achieved.

Adult↗
PubMed1997

Localized sampling of cytoplasm from Xenopus oocytes for capillary electrophoresis.

Continued progress in cellular physiology requires new measurement strategies which can be applied to solitary cells. Since many cellular signaling pathways act on time scales of a few seconds, there is a critical need for single-cell techniques with subsecond time resolution. Capillary electrophoresis shows great promise as a tool for the analysis of individual cells. In the present work, we describe a technique to load a capillary with picoliter to nanoliter volumes of cytoplasm and initiate electrophoresis in less than 500 ms. When cytoplasm was sampled from a Xenopus laevis oocyte previously loaded with fluorescein, calcium green, or a mixture of the two fluorophores, their fluorescent peaks were readily identifiable on the electropherogram. Since the volume of cytoplasm (< or = 30 nL) loaded into the capillary was much smaller than the 1 microL oocyte volume, spatially localized biochemical measurements were also possible. To demonstrate the utility of this new technique, the activity of the enzyme beta-galactosidase was measured in small regions of the Xenopus oocyte. Subcellular, subsecond sampling of oocyte cytoplasm will enable biochemical measurements with the resolution required to understand many cellular signal transduction pathways.

Animals↗
PubMed1997

Establishment and characterization of a renal cell carcinoma line from a patient with von Hippel-Lindau syndrome.

It is not known how the von Hippel-Lindau (VHL) gene and the, as yet unidentified, renal cell carcinoma (RCC) gene(s) interact to result in RCC; nor is it known if mutations in both, or all genes are necessary for this progression. The availability of a RCC cell line from a VHL patient would be useful in studies comparing sporadic RCC with RCC resulting from VHL syndrome; and for determining the relationship or interaction of the RCC gene with the VHL gene to produce a common tumor type. This paper describes the isolation and characterization of a renal cell carcinoma cell line derived from a patient with von Hippel-Lindau disease. The line is epithelial in origin and the genome contains a familial mutation in the VHL gene. Tissue culture studies indicate that this cell line, although immortalized, is not fully transformed. Chromosomal analysis performed on cells derived from disseminated primary tumor cells revealed no detectable chromosomal abnormalities. However, analysis performed on cells at passages 9, 19, 41, and 79 showed both numerical and structural chromosomal changes. The cytogenetic profile of this cell line demonstrated a number of abnormalities known to be associated with RCC from patients with and without VHL syndrome.

Adult↗
PubMed1997

Laser ablation of dyed acrylic bone cement.

Revision surgery of cemented implants is indicated when mechanical failure causes severe pain and/or loss of function for the patient. Successful revision arthroplasty of cemented implants requires complete removal of the existing cement. Removal of old cement is an arduous task often causing damage to the surrounding bone tissue. In this study, the authors investigate the use of an Argon laser and the addition of dyes to enhance the laser ablation of bone cement. Methylene blue and red dye #13 were each added separately to polymethylmethacrylate (PMMA) bone cement powder. A continuous wave Argon ion laser (lambda = 514 nm) was used for cement ablation. Cement samples were ablated at different power levels (1.5, 2.3, and 3.0 W) and exposure times (30, 60, 90, 120 sec). The results show that the Argon laser was unable to ablate undyed PMMA. However, the addition of either methylene blue or red dye #13 greatly improved cement ablation by altering the cements' absorption characteristics. Results of Student's t-tests show a statistical difference between red and blue dyed PMMA mean ablation areas at all energy levels tested (P < .0002). As expected, all red ablation areas were greater than blue ablation areas at each energy level tested since red dye absorbs more energy at 514 nm than methylene blue dye. The results of this study suggest that by selectively altering the absorption characteristics of PMMA, laser removal of bone cement can be achieved. In addition, this study also shows that bone tissue does not absorb visible light energy at 514 nm, suggesting that bone cement may be removed with minimal damage to the surrounding bone tissue.

Bone Cements↗
PubMed1997

The outcome of in vitro fertilization and embryo transfer therapy in women with endometriosis failing to conceive after laparoscopic conservative surgery.

STUDY OBJECTIVE: To compare the outcome of in vitro fertilization and embryo transfer (IVF-ET) after laparoscopic surgery in women with endometriosis with that of patients with tubal factor infertility. DESIGN: Retrospective survey of hospital and office charts using a computerized worksheet. SETTING: Lin-Kou medical center of Chang Gung Memorial Hospital. PATIENTS: Sixty-seven women with minimal to mild or moderate to severe endometriosis. Women with tubal factor infertility without other associated disorders (60 cycles) made up the control group. INTERVENTIONS: Seventy-five consecutive cycles of IVF-ET were performed in these patients who failed to conceive after laparoscopic conservative surgery. MEASUREMENTS AND MAIN RESULTS: The concentration of serum estradiol on the day of human chorionic gonadotropin (hCG) injection, the day of hCG injection, clinical pregnancy rates per transfer, number of follicles larger than 14 mm, number of embryos transferred, and implantation rate were not significantly different between women with endometriosis and those with tubal factor infertility. The number of oocytes retrieved and number fertilized were decreased, and the basal level of follicle-stimulating hormone on cycle day 3 was higher in women with both degrees of endometriosis. Women in both endometriosis groups received more follicle-stimulating hormone and human menopausal gonadotropin than those with tubal factor infertility. CONCLUSIONS: The outcome of IVF-ET in patients with endometriosis after laparoscopic surgery did not differ from that in the group with tubal factor infertility, but the former required more ampules of gonadotropin to achieve the same response. The advantages of laparoscopic surgery in women with endometriosis should be probably correlated with success of IVF-ET.

Adult↗
PubMed1997

Efficacy of isotopic 13CO2 laser laparoscopic evaporation in the treatment of infertile patients with minimal and mild endometriosis: a life table cumulative pregnancy rates study.

STUDY OBJECTIVE: To assess the efficacy of 13CO2 laser laparoscopy in treating infertile women with minimal to mild endometriosis according the American Fertility Society classification in terms of pregnancy rates. DESIGN: Prospective study. SETTING: Medical school-affiliated hospital. PATIENTS: One hundred seventy-six women whose infertility was associated with minimal or mild endometriosis diagnosed by laparoscopy. INTERVENTIONS: The patients were treated with one of four methods: 49 underwent operative laparoscopy with newly developed 13CO2 laser vaporization and/or resection; 45 were treated by operative laparoscopy with simple monopolar electrocoagulation; 43 who had undergone only diagnostic laparoscopy did not receive any treatment; and 39 received danazol 800 mg/day for 3 months after diagnostic laparoscopy. MEASUREMENTS AND MAIN RESULTS: Estimated cumulative pregnancy rates using life table analyses were indicators of treatment of success and compared among the treatments. A subgroup of 111 patients considered to have endometriosis as the only major infertility factor were also evaluated and compared among treatment options. Pregnancy rates in the CO2 laser laparoscopy group were significantly higher than in the other three groups and in endometriosis-only subset. CONCLUSIONS: Advanced laparoscopic surgery with the CO2 laser can be more efficient than other modalities in treating infertile women with minimal to mild endometriosis in terms of pregnancy rates. It appears that in experienced hands, laser laparoscopy has more favorable results than the other treatments.

Adult↗