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Y Lin

Publications and source records attributed to Y Lin.

727 records · Page 41Linked to original sources
PubMedDate not supplied

Development of an integrated microanalytical system for analysis of lead in saliva and linkage to a physiologically based pharmacokinetic model describing lead saliva secretion.

There is a need to develop reliable portable analytical systems for biomonitoring lead (Pb) in noninvasively collected saliva samples. In addition, appropriate pharmacokinetic analyses are used to quantitate systemic dosimetry based on the saliva Pb concentrations. A portable microfluidics/electrochemical device was developed for the rapid analysis of Pb based on square wave anodic stripping voltammetry, in which a saliva sample flows over an electrode surface, Pb2+ is chemically reduced and accumulated, and the electric potential of the electrode scanned. The system demonstrates a good linear response over a broad Pb concentration range (1-2000 ppb). To evaluate the relationship between saliva and blood Pb, rats were treated with single oral doses ranging from 20 to 500 mg Pb/kg of body weight, and 24 hours later were administered pilocarpine, a muscarinic agonist to induce salivation. To correlate saliva levels with internal dose, blood and saliva were collected and quantitated for Pb by inductively coupled plasma-mass spectrometry (ICP-MS) and by the microanalytical system. The quantitation with the microanalytical system was slightly less (approximately 75-85%) than with ICP-MS; however, the response was linear, with concentration suggesting that it can be used for the quantitation of salivary Pb. To facilitate modeling, a physiologically based pharmacokinetic (PBPK) model for Pb was modified to incorporate a salivary gland compartment. The model was capable of predicting blood and saliva Pb concentration based on a limited data set. These results are encouraging, suggesting that once fully developed the microanalytical system coupled with PBPK modeling can be used as important tools for real-time biomonitoring of Pb for both occupational and environmental exposures.

Animals↗
PubMedDate not supplied

synthesis and biological testing of nonionic iodinated x-ray contrast media.

A series of nonionic x-ray contrast media containing novel linkages between the triiodobenzene and polyhydroxy moieties have been prepared and screened against established criteria. Of the coupler groups examined (amide including dipeptide, carbamate, ureido, and ester), amide showed the greatest overall utility in terms of safety, solubility, stability, and ease of synthesis. Acute toxicity, solubility and stability data are summarized for each series. In the CNS, certain compounds were well tolerated and some were devoid of any excitatory effects. Intrathecal tissue irritant effects were also unremarkable. Most agents exhibited relatively high osmolalities, raising questions as to the influence of this factor on the safety of myelographic agents. Intravascularly, nonionic media appear also to offer advantages over classical ionic media. However, nonionic media can exert positive inotropic effects and exhibit high viscosity at higher iodine concentrations. Nevertheless, overall results continue to demonstrate the radiographic potential of nonionic contrast media.

Animals↗
PubMedDate not supplied

Normal canals at the fundus of the internal auditory canal: CT evaluation.

PURPOSE: Knowledge of the normal anatomy of the four bony canals located at the fundus of the internal auditory canal (IAC) is necessary during evaluation of temporal bone trauma, congenital anomalies affecting the individual nerves, and some neuro-otologic surgeries. The purpose of this work was therefore to characterize the normal appearance of the four bony canals and to measure their dimensions. METHOD: A retrospective study was performed using CT studies of the temporal bones in 50 patients to identify and characterize the bony canals for the labyrinthine segment of the facial nerve (BCFN), superior vestibular nerve (BCSVN), cochlear nerve (BCNC), and the inferior vestibular nerve (singular canal; SC) located at the fundus of the IAC. All the patients underwent high resolution temporal bone CT for evaluation of uncomplicated inflammatory (n = 49) and neoplastic (n = 1) diseases involving the temporal bone. CT studies were done using 1-mm-thick contiguous sections in axial and coronal planes. Measurements of the canals were performed by one radiologist. No patient had a prior history of trauma, vertigo, and sensorineural hearing loss or facial nerve paralysis. RESULTS: The BCFN, BCSVN, and BCNC were identified in all studies, whereas the SC was seen in 93% of studies. The BCFN, BCSVN, and BCNC arise from the fundus of the IAC, whereas the SC arises medial to the fundus. Mean +/- SD measurements (in mm) of the length and width were as follows: BCFN = 2.92+/-0.48 and 0.91+/-0.28; BCSVN = 2.36+/-0.53 and 0.89+/-0.28; BCNC = 0.93+/-0.21 and 2.13+/-0.44; and SC = 3.22+/-0.73 and 0.50+/-0.14. CONCLUSION: These small canals are routinely visualized on thin section (1 mm) CT of the temporal bone and should not be confused with fractures. This study provides baseline measurements that may be used to evaluate congenital anomalies of these canals. These data may also be helpful in the presurgical evaluation of patients undergoing singular neurectomies for benign positional vertigo.

Adolescent↗
PubMedDate not supplied

Characterization of p53 gene mutations in colorectal carcinomas from an Asian population.

A series of colorectal carcinomas from an Asian population in Singapore were analyzed for mutations in the tumor suppressor gene p53. Based on single-strand conformation polymorphism (PCR-SSCP) analysis and direct DNA sequencing, 15 of 38 tumors (39%) were found to contain mutations in exons 5-8 of the p53 gene. The point mutations were predominantly base transitions. Among the 10 transitions, 5 were at CpG dinucleotide sites. One-third (5/15) of the mutations were found at previously identified hotspot codons 175, 248 and 282. In one case, an insertion of a 6-base pair sequence was found. p53 mutations did not correlate with tumor histological grade, Dukes' stage, or metastases. However, tumors at the distal site showed a higher proportion of mutations than the proximal site. Further, no mutation was found in the normal mucosa adjacent to tumor site, suggesting that no germ-line mutations were present. The results were compared with those from other studies and are discussed in connection to possible etiological factors that are specific to the local population.

Amino Acid Sequence↗
PubMedDate not supplied

A nonsaponification method for the determination of carotenoids, retinoids, and tocopherols in solid human tissues.

There has been an increasing interest in the measurement of carotenoids, retinoids, and tocopherols in human tissues because some of these micronutrients have been shown to have chemopreventive activity. Since clinical tissue samples obtained for analysis are usually small in quantity, a sensitive analytical procedure that can simultaneously measure all the micronutrients of interest in one small piece of human tissue is necessary. Moreover, some solid tissues, such as skin, are very difficult to homogenize unless they are first saponified in alcoholic KOH, but the saponification often causes substantial destruction of some micronutrients. Thus, a nonsaponification procedure using collagenase to facilitate homogenization was developed. Solid tissues are first incubated in a collagenase solution, homogenized, then incubated in a protease solution, followed by precipitation of tissue proteins and extraction with hexane. Collagenase digestion facilitates homogenization, and protease digestion increases the extractable amounts of the micronutrients from certain tissue samples. In this study, the recovery and precision (coefficient of variation) of the new procedure was determined. In addition, the extracted amounts of seven carotenoids, two retinoids, and two tocopherols from human skin, cervical/ovarian tissue, as well as sarcoma and kidney tumors using the new procedure and a commonly applied saponification procedure were compared.

Adult↗
PubMedDate not supplied

Micronutrient concentrations in paired skin and plasma of patients with actinic keratoses: effect of prolonged retinol supplementation.

Much of our knowledge about the relationship between micronutrients and cancer comes from studies in which plasma (serum) micronutrient levels have been correlated with cancer incidence; however, the relationship between the concentrations of micronutrients in the plasma and in the target tissues has not been established. Ninety-three subjects (62 males and 31 females ages 42-86, median age 69) with actinic keratoses were recruited for investigation of this relationship. The subjects were randomly assigned and received placebo or retinol (25,000 IU/day) intervention for 48 to 65 months as part of a skin cancer chemoprevention trial. Shortly before the end of the trial, three fasting plasma samples and one skin biopsy were obtained from each subject. The concentrations of lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, beta-carotene, cis-beta-carotene, retinol, retinyl palmitate, alpha-tocopherol and gamma-tocopherol in the plasma and skin were simultaneously measured using HPLC. The profiles of the eleven micronutrients in the plasma and skin were similar. Lycopene, beta-carotene and alpha-tocopherol were the predominant micronutrients in both plasma and skin, but the ratio of retinyl palmitate to retinol was much greater in the skin than plasma. The three fasting plasma concentrations from the same subject during a one-month period were very consistent; however, the between-person variations were very large. The retinol supplementation caused a significant increase in the plasma concentrations of retinol, retinyl palmitate, lutein and alpha-tocopherol, especially retinyl palmitate as well as the skin concentrations of retinol and retinyl palmitate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗