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Biomedical subjects

M L Lee

Publications and source records attributed to M L Lee.

At least 55 records · Page 3Linked to original sources

Validation of K x-ray fluorescence bone lead measurements by inductively coupled plasma mass spectrometry in cadaver legs.

K x-ray fluorescence (KXRF) systems are being used in a growing number of epidemiologic studies to measure bone lead levels as a biological marker of accumulated lead exposure. Although validation of the KXRF technique in lead-doped phantoms and bare bone specimens has been repeatedly demonstrated, few studies have compared KXRF to chemical measurements of actual intact cadaver limbs (with skin and soft tissues). In this study, lead levels in eight amputated human legs were measured by KXRF; after dissection, levels in the bare bones were again measured by KXRF and then by inductively coupled plasma mass spectrometry (ICP-MS). We observed close agreement between the KXRF and ICP-MS measurements with correlation coefficients for both the tibia and patella greater than 0.9. In this study we provide further support for the validity of KXRF measurements, particularly with respect to the patella.

Aged↗

Vibration perception thresholds in workers with long term exposure to lead.

OBJECTIVES: To evaluate the impact of long term occupational exposure to lead on function of the peripheral nervous system as reflected by vibration perception threshold (VPT), measured with a portable vibrameter. METHODS: 217 Workers in a lead battery factory were required to have an annual blood lead measurement during each of the 5 years preceding this study. All were invited to take the VPT test. A total of 206 workers were studied. The associations were analysed between VPTs and current blood lead concentration, mean concentration of blood lead over the past 5 years, maximum blood lead concentration during the past 5 years, index of cumulative blood lead (ICL), time weighted index of cumulative blood lead (TWICL), and percentage of lifespan spent at work in the plant, as well as the other potential confounders. Ordinary multiple regressions, generalised additive models, and hockey stick regression analyses were used to explore the potential existence of a threshold effect of blood lead variables on VPT. RESULTS: VPT at a frequency of 220 Hz ranged from 6 to 100 (10(-2) g, or 0.098 m/s(2)) with a mean (SD) of 19.8 (14.2) for the feet and from 4 to 43 with a mean (SD) of 10.2 (6.1) for the hands. The five variables of exposure to lead were all significantly correlated with VPT of the feet but not the hands. In multiple linear regression analyses, the mean of the blood lead concentrations and the TWICL were significantly associated with VPT of the feet. The relation between VPT of the feet and mean blood lead was shown to be a J shaped curve with a generalised additive model and local smoothing technique. In the hockey stick regression, evidence was found of a threshold effect at a mean blood lead concentration of 31 microgram/dl. Above this threshold it was estimated that each increase of 1 microgram/dl mean blood lead over 5 years would increase VPT of the feet by 0.29 (10(-2) g) or 0.028 m/s(2) (at a frequency of 220 Hz) with other potential confounders held constant. CONCLUSION: This study suggests that measurement of vibration sensory threshold is a relatively effective tool for detecting lead neuropathy in field studies, and that lead might cause sensory neuropathy with an effect threshold corresponding to a 5 year mean blood lead concentration of 31 microgram/dl.

Adult↗

Duration of survival for disseminated malignant melanoma: results of a meta-analysis.

The aim of this study was to estimate the survival experience of patients with disseminated malignant (stage IV) melanoma regardless of the treatment received. Articles, including abstracts, published in the English language medical literature between 1985 and 1999 were identified through an electronic key word literature search using MEDLINE and PUB-MED together with the reference lists of review articles. Some literature published prior to 1985 was identified through these searches and was also included. Median survivals were calculated across all the data, for the post- and pre-1985 periods, and for the larger studies alone (n > or = 20) using a weighting scheme based on sample size and study characteristics. An attempt was also made to estimate the frequency of long-term survival to 2, 3 and 5 years in this patient population (also stratified according to the study publication time). A total of 83 studies were identified comprising a total of 6322 patients. The overall median survival from diagnosis of stage IV melanoma was estimated to be 8.1 months (approximate 95% confidence interval [CI] 7.3-8.9 months). For the 59 studies published since 1985 (covering 3715 patients), the median survival was 8.9 months (approximate 95% CI 7.9-9.9 months). Prior to 1985, the median survival was 5.8 months (approximate 95% CI 4.5-7.1 months). For the 67 studies with at least 20 patients (a total of 6024 patients), the median survival was 8.1 months (approximate 95% CI 7.2-9.0 months). Long-term survival for the post- and pre-1985 periods over 2, 3 and 5 years was estimated to be 13.6%, 9.7% and 2.3%, respectively, and was consistent across the two time periods. In conclusion, while the survival experience in stage IV melanoma patients has improved since 1985, the use of varied approaches to treat this disease has not produced a favourable long-term prognosis. This meta-analysis will allow the survival results from current and future trials to be compared with the expected survival based on cumulative findings to date.

Humans↗

Treatment of rheumatoid arthritis with a DR4/1 peptide.

OBJECTIVE: To determine the safety and potential clinical efficacy of primary and booster injections of a DR4/1 peptide in patients with active rheumatoid arthritis (RA) despite methotrexate therapy. METHODS. Subjects with active RA were enrolled in a randomized, placebo controlled, double blind, dose-escalating clinical trial of synthetic DR4/1 peptide containing the shared epitope. The primary injection of the DR4/1 peptide in alum adjuvant was administered at one of 3 doses, 1.3, 4.0, and 13 mg, followed by up to 3 or 4 booster injections every 6 or 8 weeks at the same dose. The primary outcomes were the occurrence of adverse effects and changes in measures of immune function. Clinical efficacy was assessed using the American College of Rheumatology 20% criteria for clinical improvement. RESULTS: Fifty-three patients were entered into the trial, including 44 who completed the study. In the absence of any observations of a dose response to the DR4/1 peptide injections, the 3 dosage groups were combined for subsequent analysis into 3 groups: patients receiving DR4/1 peptide injections every 6 weeks, patients receiving DR4/1 peptide injections every 8 weeks, and a placebo group. At all doses and each dosing interval the primary and booster injections of synthetic DR4/1 peptide were well tolerated and did not produce any significant changes in lymphocyte counts or evidence of generalized immunosuppression. Analysis of clinical efficacy showed that the 6 week group had trends toward improvement in disease measures. CONCLUSION: Primary and booster injections of the DR4/1 peptide containing the shared epitope were safe and did not broadly suppress immune function.

Adolescent↗

Increased brain serotonin synthesis in migraine.

OBJECTIVE: To measure brain serotonin synthesis with PET using the tracer alpha-[11C]methyl-L-tryptophan in migraine patients. BACKGROUND: Although the cause of migraine remains poorly understood, there is considerable evidence to support a role of the neurotransmitter serotonin in the pathophysiology of migraine. METHODS: We studied 11 women (aged 33+/-7.7 years) with a diagnosis of migraine according to International Headache Society criteria and 8 healthy women (aged 29+/-9.2 years). Five patients were studied before and after chronic treatment with propranolol or nadolol. RESULTS: Serotonin synthesis capacity (K-complex) values in migraine patients were higher than those measured in controls throughout the brain (p = 0.016); mean K-complex for whole brain was 0.0077 + 0.0020 mL/g/min in patients with migraine and 0.0054+/-0.0003 mL/g/min in controls. The regional pattern did not differ between the two groups. However, the K-complex for whole brain in the subgroup of migraine patients with aura (n = 3) did not differ from that of the control group (p = 0.32). In the five patients studied twice (before and after treatment), we found a trend of increased whole-brain K-complex after drug treatment (p = 0.06). CONCLUSIONS: Our findings indicating increased brain serotonin synthesis capacity in migraine patients are consistent with previous reports of systemic alteration of serotonin metabolism in patients without aura. Our results also suggest that the mechanism of action of beta-adrenergic antagonists for migraine prophylaxis may involve regulation of serotonin synthesis.

Adrenergic beta-Antagonists↗

Transarterial occlusion of patent ductus arteriosus with Gianturco coils in pediatric patients: a preliminary result in central Taiwan.

OBJECTIVE: We wish to present the preliminary result of transarterial occlusion of patent ductus arteriosus (PDA) with Gianturco coils in pediatric patients in central Taiwan. MATERIALS AND METHODS: We attempted occlusion of PDA with Gianturco coils in a total of 26 consecutive patients, 13 infants and 13 children, 23 female and three male, between July 1 1997 to September 30 1998. Median patient age was 2.57 years (from 0.25 to 14.02 years old). Median patient weight was 10.8 kg (4.0 to 36.0 kg). Premature babies with PDA, full-term babies who were less than three months old and patients who had other congenital heart disease were not included in this study. All PDAs were approached transarterially from the femoral artery. Coils were selected to provide a helical diameter that was twice or more the minimum ductus diameter and a length approximating five loops. In five patients who had a PDA diameter > or =3.5 mm, we used a snare technique to assist coil delivery beforehand, and to test coil stability, or to retrieve coil that had migrated to the pulmonary artery afterwards. Physical auscultation, chest radiographs and echocardiography with color Doppler were done in all patients within 24 h, and one, two, three, six and 12 months after coil occlusion. RESULTS: The median ductus minimum diameter was 2.3 mm (range, 1.0 to 4.7 mm). Fifteen patients had the megaphone type (type A), four had the window type (type B), five had the tubular type (type C), one had the aneurysmal type (type D) and one had the elongated conical type (type E). Twenty-one patients underwent single coil occlusion and five had multiple coils occlusion. Twenty-one patients had immediate angiographic closure of the ductus and disappearance of heart murmur at 15 min after the procedure. Dark-brown urine (hemoglobinuria) was found in one patient, 10 h after the first procedure, due to a mild residual ductal shunt. Two more coils were implanted in a second procedure that was performed within 24 h, and the ductus was completely occluded. The dark-brown urine regressed. At one month follow-up, four patients had mild residual ductal shunts, which were completely occluded by one more coil in three patients and by two more coils in the other patient. Malpositioned coils were deployed in five patients immediately after the procedure. In total, the closure rate at 15 min, within 24 h, and at one, two, three, six and 12 months were 81, 85, 85, 100, 100, 100 and 100%, respectively. In one year of follow-up, there was no instance of coil migration, ductus reopening or stenosis of the left pulmonary artery. CONCLUSIONS: Transarterial occlusion of PDA, with a Gianturco coil having approximately five loops, can be effectively achieved in patients with a minimum ductus diameter up to 4.7 mm. In patients with a ductus of more than 3.5 mm, the snare-assisted technique was employed advantageously to control coil delivery with accuracy and stability. Coil malposition or migration can be easily retrieved using a 10-mm Nitnol snare catheter. Hemoglobinuria, due to intravascular hemolysis, may regress within 24 h after the second attempt at coil implantation.

Adolescent↗

Capillary electrophoresis using diol-bonded fused-silica capillaries.

In this paper, 3-glycidoxypropyltrimethoxysilane was used to produce diol-bonded capillaries at room temperature for capillary electrophoresis (CE). A variety of standard reference compounds and authentic biological samples including ribonucleotides, peptides and proteins were used to test the columns. It was found that greatly suppressed electroosmotic flow was measured over a pH range of 3-10. Lower than 1.6% relative standard deviation (> 10 runs) in migration time was observed for the analysis of test proteins. For real samples of ribonucleotides in tumor cell extracts, approximately 1 million theoretical plates and excellent peak shapes were obtained. The high column efficiency and symmetrical peaks allowed the separation of samples with only 0.6% maximum difference in migration times. The diol-bonded fused-silica capillary columns were stable when used in a pH range of 2-8 under typical CE conditions. The column preparation method involved a simple dynamic coating procedure at room temperature, greatly simplifying the more typical static coating methods that require vacuum pumps and ovens.

Amino Acid Sequence↗

Prevalence of TT virus DNA in eastern Taiwan aborigines.

We studied the prevalence of TT virus (TTV) DNA in the general population of the eastern Taiwan aborigine villages, about 11% (34 of 317). There is no association between the presence of HBsAg and TTV DNA or between the presence of HCV RNA and TTV DNA. Therefore, the infection of HBV or HCV and the presence of TTV DNA appear to be independent from each other. The association between the presence of TTV DNA and the elevated alanine aminotransferase (and/or aspartate aminotransferase) activity was also investigated. The presence of TTV DNA was not found to be correlated with abnormal liver function (P = 0.574) when age, gender, and the presence of HBsAg, HCV RNA, and HGV RNA were all considered in the assay. The sequence homology of TTV DNA fragments between different isolates from Taiwan and N22 (the clone obtained from the original prototype strain) from Japan ranged from 84 to 97%. The recombinant protein encoded by the TTV DNA fragment corresponding to the open reading frame of N22 was expressed in E. coli successfully. However, no serum response against the recombinant protein was detected.

Adolescent↗

Relationship of blood lead levels to personal hygiene habits in lead battery workers: Taiwan, 1991-1997.

BACKGROUND: The blood lead concentrations of workers in lead battery factories are more than 4 times higher than those of the general population in Taiwan. Therefore, efforts are needed to reduce lead exposure in this high-risk population. A health promotion program on personal habits that reduce lead exposure has been carried out in a lead battery factory since 1991. This study investigated the longitudinal relationship of workers' blood lead concentrations and personal hygiene habits from 1991 through 1997. METHODS: In each of the 7 years of the study, occupational physicians questioned workers regarding nine personal hygiene items, personal information, and medical history before their annual health examination. The relationship between blood lead concentrations and personal hygiene habits was analyzed by longitudinal multiple regression in a mixed effect model with adjustment for potential confounders. In addition, the risk ratio of a blood lead concentration exceeding 40 micrograms/dL in men and 30 micrograms/dL in women (the action levels set by the Department of Health, Taiwan) was estimated by generalized estimating equations. RESULTS: Blood lead levels decreased significantly in the first 5 years of the study. The personal habits most closely related to blood lead concentrations were smoking at work sites (estimated coefficient = 3.13, P < 0.001), and eating at work sites (estimated coefficient = 1.38, P = 0.069). The risk ratio for workers with both these habits exceeding the action level of blood lead was 2.93 (95% CI 1.27-6.77). Difference in job titles, however, accounted for a major portion of the variance in blood lead. For example, working in "pasting" and "plate-cutting" was associated with blood lead elevations > 20 micrograms/dL in comparison to the "low- or no-exposure jobs." CONCLUSIONS: Health promotion programs can decrease exposure of lead workers; reducing the practices of smoking and eating at work sites should be the core of such programs. However, a major reduction in lead exposure for some jobs (e.g., "pasting" and "plate cutting") in lead battery factories in Taiwan is unlikely to occur without major engineering changes.

Feeding Behavior↗

Design and evaluation of a new capillary electrochromatography system.

A new computer-controlled capillary electrochromatography (CEC) system was built. Up to +/- 60 kV can be used for CEC separation, and buffer vials can be pressurized to prevent bubble formation and to facilitate conditioning and rinsing of columns. This CEC system is compact and flexible. Short columns can be used to achieve fast separations. A fiber optic detection assembly is used to separate the main body of the UV detector from the high potential to prevent potential discharge and disturbance of the UV absorbance signal. This system was evaluated by separating 16 polycyclic aromatic hydrocarbons (PAHs) on different types of octadecyl silane (ODS) particles. Over 200,000 plates/m (k = 4.4) were obtained using 1.5 microm ODS particles. Voltage programming was used to reduce the analysis time by nearly 50%.

Chromatography, Liquid↗

Chronic elbow instability.

Chronic elbow instability without fractures in adults can be broken down into three types: (1) valgus instability, (2) posterolateral rotator instability, and (3) isolated radial head instability. By far the most common is valgus instability, which usually occurs in throwing athletes as a result of repetitive microtrauma to the anterior band of the medial collateral ligament. Surgical treatment is aimed at reconstruction of the anterior band of the medial collateral ligament. Posterolateral rotatory instability is much less common and is diagnosed by the lateral pivot-shift test of the elbow. It is usually the result of an undiagnosed acute injury to the lateral ulnar collateral ligament. Surgical treatment is aimed at its reconstruction. Isolated radial head subluxation in adults is extremely rare. The essential lesion is a disruption of the annular ligament. Surgical treatment is either radial head resection or reconstruction of the annular ligament.

Chronic Disease↗

Evidence of altered energy metabolism in autistic children.

1. In this pilot study, the authors investigated the hypotheses there are increased concentrations of lactate in brain and plasma and reduced brain concentrations of N-acetyl-aspartate (NAA) in autistic children. 2. NAA and lactate levels in the frontal lobe, temporal lobe and the cerebellum of 9 autistic children were compared to 5 sibling controls using MRS. Plasma lactate levels were measured in 15 autistic children compared to 15 children with epilepsy. 3. Preliminary results show lower levels of NAA cerebellum in autistic children (p = 0.043). Lactate was detected in the frontal lobe in one autistic boy, but was not detected any of the other autistic subjects or siblings. 4. Plasma lactate levels were higher in the 15 autistic children compared to 15 children with epilepsy (p = 0.0003). 5. Higher plasma lactate in the autistic group is consistent with metabolic changes in some autistic children. The findings of altered brain NAA and lactate in autistic children suggest that MRS may be useful characterizing regional neurochemical and metabolic abnormalities in autistic children.

Adolescent↗

Relationship of blood pressure to cardiovascular death: the effects of pulse pressure in the elderly.

PURPOSE: To investigate the relationship of systolic and diastolic blood pressure to fatal myocardial infarction, fatal stroke and other death related to cardiovascular diseases (CVD). METHODS: The study was based on a prospective longitudinal study conducted by the Veterans Administration at the Boston Outpatient Clinic. Participants are male volunteers from the greater Boston area. Main outcome measures are fatal myocardial infarction, fatal stroke and other deaths related to cardiovascular diseases. The method of pooled logistic regression was used for statistical analysis. RESULTS: For younger men (age 21-59), after adjusting for effects of other risk factors, when systolic and diastolic blood pressure were considered separately, SBP was predictive of cardiovascular death (SBP: RR = 1.23; 95% CI = (1.05, 1.45) per 10 mmHg of increase), and DBP showed a nonsignificant positive trend in relation to cardiovascular death (DBP: RR = 1.27; 95% CI = (0.95, 1.69) per 10 mmHg of increase). For older men (age 60-85), when SBP and DBP were considered separately, SBP (RR = 1.26; 95% CI = (1.02, 1.55) per 15 mmHg of increase) was directly related, but DBP (RR = 1.05; 95% CI = (0.83, 1.32) per 8 mmHg of increase) was not related to cardiovascular death. However, for the elderly group, when SBP and DBP were considered jointly in the regression model, then the regression coefficient of DBP (beta = -0.018, p = 0.30) was of approximately the same absolute magnitude as that of SBP (beta = 0.021, p = 0.02) but opposite in sign. For younger men, when SBP and DBP were considered jointly, SBP (beta = 0.021, p = 0.049) but not DBP (beta = -0.001, p = 0.953) was positively related to cardiovascular death. CONCLUSIONS: We found that, for the elderly, pulse pressure (SBP-DBP) may be a more accurate predictor of cardiovascular death than either SBP or DBP alone. The relative risk per 35 mmHg of increase of pulse pressure, which equals the approximate interval from the 10th to the 90th percentile in the elderly group, is 2.1 with 95% CI = (1.1, 3.8). In younger subjects, SBP, but not DBP, is an independent predictor of fatal CVD.

Adult↗

Determination of reasons for cessation of participation in serial plasmapheresis programs.

BACKGROUND: An earlier retrospective review of records of over 500 remunerated donors participating in plasmapheresis programs at various levels of frequency for 10 or more years showed that there were no significant differences in mean values for total protein, microhematocrit, body weight, and individual serum proteins, regardless of the number of annualized donations for each of four frequency groups. Although these data demonstrated that donors undergoing serial plasmapheresis for 10 or more years were able to successfully continue in such programs, the review did not include information relative to individuals who had discontinued their participation. The current study investigated reasons that donors drop out of plasmapheresis programs. STUDY DESIGN AND METHODS: Donors who had successfully undergone plasmapheresis at least 20 times within a recent 6-month period but who had failed to appear for at least 30 days subsequent to their last donation were defined as potential subjects for the study. Staff members at the participating center contacted the donors, inviting them to return to the center to participate in a survey. Donors were also asked for a blood sample upon their arrival at the plasma center; samples were tested for total and various serum proteins. RESULTS: A total of 409 eligible subjects appeared at the centers for the survey, and 375 blood samples were analyzed for proteins. Survey responses indicated that the predominant reasons for an end to participation were socioeconomic in nature. Serum protein findings were compared to the most recent results obtained while the donors were active in the plasmapheresis program. Slightly higher mean serum protein findings were seen for samples collected on the survey date. CONCLUSION: A review of the aggregate responses obtained in the survey indicates that the predominant reasons that donors ceased to participate were not health-related: the remuneration was no longer needed, and work schedule conflicts, time constraints, and relocation were frequently cited.

Adult↗