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Biomedical subjects

Y Lee

Publications and source records attributed to Y Lee.

557 records · Page 31Linked to original sources
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Enrichment and identification of fetal trophoblast cells from first trimester maternal cervical lavage and uterine blood specimens.

First trimester prenatal diagnosis of fetal aneuploidies is an active area of research despite years of disappointing data employing maternal peripheral blood samples. To remedy this situation we have investigated other first trimester maternal specimens attempting to find a consistent fetal cell source. Using our previously established positive enrichment procedure along with a commercially available depletion method, fetal trophoblast cells were identified employing immunocytochemistry using an antibody cocktail or by using mRNA in-situ hybridization employing a cocktail of trophoblast specific probes. Fetal origin of positively identified cells was verified using interphase fluorescent in-situ hybridization (FISH) for X and Y-chromosomes. Artificial model systems were established that indicated yields of trophoblast cells and allowed the enrichment procedure to be optimized for minimal losses from maternal specimens. We demonstrate herein that blood drawn from maternal vessels near the placental implantation site to be the most consistent source of fetal cells from any first trimester maternal specimen described to date. In addition, a high yield of multinucleated syncytiotrophoblast cells was obtained using a cell depletion strategy to enrich the target cells. The safety of the procedure or even the clinical utility of blood drawn from maternal vessels near the placental implantation site is yet to be demonstrated.

Cell Separation↗
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In vitro and in vivo susceptibility of atypical mycobacteria to various drugs.

In vitro sensitivities to various drugs of a total of 106 strains of atypical mycobacteria were studied in modified Dubos Tween albumin liquid medium. Eight triple-drug combinations of antituberculous drugs were also evaluated in vitro for their potentiated activities. Minimal to moderate potentiation was demonstrated in the majority of the combination. From the results, the triple-drug combination--including rifampin, one of three aminoglycosides (streptomycin, kanamycin, viomycin), and either ethionamide or ethambutol--might be recommended for Mycobacterium kansasii infections. Against Mycobacterium avium-intracellulare infections, rifampin-kanamycin-ethionamide or rifampin-kanamycin-ethambutol might be the choice if we were to select any triple-drug regimen. None of the triple-drug regimens thus far tested on M. avium-intracellulare were active enough to recommend fully for clinical use. In vivo experimental chemotherapy of murine infection with Mycobacterium intracellulare (TMC 1469) on a five-drug regimen, kanamycin-rifampin-cycloserine-ethambutol-ethionamide, showed a moderate therapeutic effect but the infection was not eradicated.

Animals↗
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Cervical tuberculous lymphadenitis: CT findings.

OBJECTIVE: Cervical tuberculous lymphadenitis (CTBL) is still an important cause of neck mass in many countries. The purpose of this study is to analyze the CT findings of CTBL and compare them with those of malignant lymphadenopathies and pyogenic abscesses in the neck. MATERIALS AND METHODS: We retrospectively reviewed the CT scans of 32 CTBLs, 25 malignant lymphadenopathies, and 12 pyogenic abscesses in the neck. Attenuation value, enhancement pattern, and surrounding fat plane were evaluated. RESULTS: The CT findings of CTBL were classified into four types: type 1, homogeneous soft tissue density; type 2, central low density and peripheral rim enhancement with relative preservation of surrounding fat planes; type 3, multilocular central low densities and peripheral rim enhancement with obliteration of surrounding fat planes; and type 4, large confluent low density with peripheral rim enhancement and loss of lymph node architecture. Among the 32 cases of CTBL, type 3 was most frequently noted (59.4%) followed by type 2 (21.9%), type 4 (15.6%), and type 1 (12.5%). The enhancing rim of CTBL was usually thick and irregular in contrast to some malignant lymph nodes showing thin and regular rim enhancement. The degree of surrounding fat plane obliteration was less in type 4 CTBL than in pyogenic cervical abscess. CONCLUSION: Cervical tuberculous lymphadenitis usually shows a central low density and peripheral rim enhancement that tends to be thick and irregular compared with a malignant lymphadenopathy. Multilocular low densities with peripheral enhancement and a large confluent low density with less degree of fat plane obliteration than a pyogenic abscess are suggestive features of advanced CTBL.

Abscess↗
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Tuberculous abscess in retromammary region: CT findings.

PURPOSE: Our goal was to evaluate CT findings of tuberculous abscess in the retromammary region of the breast. METHOD: Four patients with tuberculosis extending from the retromammary region to the pleura were examined by CT and the findings were evaluated. All cases were also examined with mammography and two cases were evaluated with sonography. Diagnosis was confirmed by acid-fast bacillus stain, culture, and histologic examination. RESULTS: Mammography showed relatively smoothly marginated, round mass density in two cases, nodular density in one, and focal bulging of the pectoral wall in one. A sonogram demonstrated in two cases a fistulous connection from the heterogeneous, fluid-containing lesion with floating internal debris in the retromammary region to the thoracic cavity. In all four cases, CT showed relatively smoothly marginated, inhomogeneous, hypodense lesions with surrounding rims of the cold abscess type. A direct fistulous connection from the retromammary lesion through the thoracic wall into the pleura was seen in two cases. Destroyed rib fragments within the abscess were noted in two cases. CONCLUSION: A tuberculous abscess in the retromammary region usually showed on CT a focal, smoothly marginated, inhomogeneous, hypodense lesion with a surrounding enhancing rim. A direct fistulous connection with the pleura or a destroyed rib fragment in the abscess as revealed by CT can be helpful in the differential diagnosis of other infectious types of retromammary abscess.

Abscess↗
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Investigations on the near surface dose for three 10-MV x-ray beam accelerators with emphasis on the reduction of electron contamination.

A study of three 10-MV x-ray clinical accelerators with emphasis on the reduction of electron contamination was conducted. This study, which was performed with different types of trays and filters, suggests that, at 100-cm source-surface distance (SSD), Pb can be used as an effective filter material up to 30 X 30 cm2; however, due to its transparency, a Clear-Pb tray is useful for field sizes up to a 20 X 20 cm2. Percent depth doses for a few selected depths and field sizes at this nominal SSD were examined. No significant differences, with the exception of the location of Dmax, amongst the three accelerators were noticed.

Electrons↗
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Lead shielding thickness for dose reduction of 6-MeV electrons for different square fields.

The relative percent dose reduction by lead (Pb) of 6-MeV electrons produced by Clinac 1800 for 6 X 6, 10 X 10, 15 X 15, 20 X 20, and 25 X 25 cm2 cones both with and without buildup is measured. The thickness of Pb required to attenuate the intensity of the primary electron beam to 95% and 98% depends upon the cone size and upon the depth in phantom at which transmission measurements are made.

Electrons↗
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Investigation on the reduction of electron contamination with a 6-MV x-ray beam.

Experimental investigations have been carried out on the reduction of electron contamination of a 6-MV x-ray beam of Clinac model 1800 for square field sizes 5 X 5 to 30 X 30 cm2 in steps of 5 cm and for rectangular field sizes 19 X 7 and 7 X 19 cm2. The electron contamination of both the open beam and the beam with the tray can be effectively reduced by placing a lead foil filter immediately below the blocking tray. Measurements at 100-cm source-skin distance with filter in place showed a reduction in dose in the buildup region and also a displacement of the location of Dmax to greater depths, even for small field sizes such as 10 X 10 cm2.

Electrons↗
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Lead shielding thickness for dose reduction of 5 MeV electrons.

The relative percent intensity reduction by lead (Pb) of 5 MeV electrons produced by Siemens Mevatron 77/74 for 5 cm diameter, 10 X 10, 15 X 15, and 20 X 20 cm2 cones both with and without buildup is measured. The thickness of lead (Pb) required to attenuate the intensity of the primary electron beam to 95% and 98% depends upon the cone size and upon the depth in phantom at which transmission measurements are made.

Electrons↗
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Characterization of endothelial cell locomotion using a Markov chain model.

A Markov chain model was developed to characterize the two-dimensional locomotion of bovine pulmonary artery endothelial (BPAE) cells cultured with or without basic fibroblast growth factor (bFGF). This model provides a detailed description of the migration process by computing the following locomotory parameters: (i) the speed of cell locomotion; (ii) the expected duration of cell movement in any given direction; (iii) the probability distribution of turn angles that will decide the next direction of cell movement; (iv) the frequency of cell stops; and (v) the duration of cell stops. Eight directional states and a stationary state were used in our Markov analysis. From cell trajectory data, the transition probabilities among the various states and the waiting times for the directional and the stationary states were computed. The steady-state probabilities were also calculated to obtain the ultimate direction of cell motion and, thus, determine whether cell motion was random. Our results showed how the addition of bFGF enhanced the locomotory capability of BPAE cells. Cells cultured with 30 ng/mL bFGF had lower probability of moving to the stationary state than those cultured without bFGF. In addition, cells cultured with 30 ng/mL bFGF remained in the stationary state for shorter periods of time than cells cultured without bFGF. In both these cases, however, the transition probabilities from the stationary state to any directional state were uniformly distributed and were not affected by the presence of bFGF.

Algorithms↗
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Association of comorbidity with depressive symptoms in community-dwelling older persons.

BACKGROUND: Depression in later life poses a serious threat to mental health and well-being of older persons burdened with medical illnesses. Comorbid medical conditions independently, as well as through interactions, may influence the degree of depressive symptoms manifested by the elderly. Insight into the role medical comorbidity plays in the manifestation of depression may help to better address both physical and mental health care needs of the depressed elderly. OBJECTIVE: To examine independent and synergistic effects of comorbid medical conditions in the presentation of depressive symptoms among older adults living in the community. METHODS: Data from a national survey of community-dwelling older persons aged 60 years and over (n = 2,058) in Korea were used. The levels of depression were assessed using an eleven-item Center for Epidemiological Studies Depression Scale. Comorbidity was defined as the number of chronic medical conditions and the combination of disease pairs. Sociodemographic characteristics, self-rated health, physical functioning, history of hospital admission in the past year, frequency of contact with friends or neighbors, and emotional support were used as covariates. RESULTS: Overall, persons with a medical condition compared to those without tended to show a higher depressive symptom score. Comorbidity, in terms of the number of medical conditions, tended to show a significant linear association with depression, controlling for confounders. More important, independent effects of medical conditions as well as a tendency to synergy among specific medical conditions were found, with notable gender differences. CONCLUSION: Given the significant but complex association of comorbid medical conditions with depressive symptoms in aged persons, clinicians should exercise care to address their physical and mental health needs within a common therapeutic context.

Aged↗
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Corticosteroid-induced psychotic and mood disorders: diagnosis defined by DSM-IV and clinical pictures.

The authors investigated long-term outcome and treatment strategy of corticosteroid-induced psychotic and mood disorders as defined by DSM-IV. Review of medical records of 2,069 referral patients revealed 18 applicable patients. Their clinical characteristics, longitudinal courses, and treatments were studied. The authors identified 15 patients with mood disorder and 3 patients with psychotic disorder. Increasing doses or resumption of corticosteroids had the strongest influence on the psychiatric course. These two corticosteroid-induced psychiatric disorders may have different pathophysiological substrates closely related to patient vulnerability. Effective psychopharmacological treatment options were indicated with consideration being given to the underlying diseases.

Adult↗
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Two cases of fetal akinesia/hypokinesia sequence.

Two cases of fetal akinesia sequence are described. Both showed facial anomalies, arthrogryposis multiplex, bilateral camptodactyly, and pulmonary hypoplasia. One child had degeneration of large motor neurons of the thoracolumbosacral spinal cord and irregular atrophy of diaphragm; the other had left microphthalmia, hemiatrophy of the left temporal lobe with calcification of degenerated neurons, and hypoplasia of the cervothoracic spinal cord with decrease and degeneration of neurons. The iliopsoas and intercostal muscles showed focal myofiber atrophy. These findings suggested that some instances of this fetal akinesia syndrome might be due to neuromuscular dysfunction that occurred in utero and may have various causes.

Abnormalities, Multiple↗
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MR imaging of shaken baby syndrome manifested as chronic subdural hematoma.

Shaken baby syndrome (SBS) is a form of child abuse that can cause significant head injuries, of which subdural hematoma (SDH) is the most common manifestation. We report the MRI findings of chronic SDH in three cases of SBS, involving two-, three- and eight-month-old babies. The SDH signal was mostly low on T1-weighted images and high on T2-weighted images, suggesting chronic SDH. In chronic SDH, a focal high signal on T1-weighted images was also noted, suggesting rebleeding. Contrast-enhanced MRI revealed diffuse dural enhancement.

Brain↗
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Changes of host natural killer cell activity in F344 rats during gastric carcinogenesis induced by N-methylnitrosourea.

To evaluate the role of NK cells during gastric carcinogenesis, especially in early stage of tumorigenesis, the changes of NK activity was examined. Rats were given N-methylnitrosourea (MNU) at a concentration of 100 ppm in their drinking water for 15 weeks. Rats were sacrificed sequentially on week 15, 18, 20, and 40 of the experimental period. Histological changes such as mild erosion, regenerative changes, focal or severe atypical lesions and invasive adenocarcinoma were observed sequentially in the pyloric region. Adenomatous hyperplasia was induced in majority of the rat stomach in MNU-treated group and incidence of adenocarcinoma was 20% in 40 weeks of MNU-treated group. There was no difference in NK activity until week 20, however, it was increased in MNU-treated rats at 40 week, when compared to that of untreated control group. From week 15, the ratio of pepsinogen altered pyloric gland (PAPG) between untreated control and MNU-treated rats was progressively increased, but there was no significant increment in the number of PAPG in MNU-treated rats after 20 weeks. NK activity was increased in MNU-treated rats, when compared to that of untreated control group. These results suggest that PAPG is a relatively good marker for the evaluation of progression of gastric carcinogenesis and increased NK activity is shown, especially in early stage of gastric carcinogenesis.

Animals↗
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Semisynthesis of human growth hormone-releasing factors by alpha-amidating enzyme catalyzed oxidation of glycine-extended precursors.

Recombinant alpha-amidating enzyme was used in the semisynthesis (1-5 mg scale) of human growth hormone-releasing factor, GRF(1-44)-NH2, by in vitro enzymatic oxidation of the glycine-extended precursor, GRF(1-44)-Gly-OH, prepared by solid-phase synthesis. The equipotent analog, GRF(1-29)-NH2, and the superactive analog, [Ala15]-GRF(1-29)-NH2, were also prepared by this route and were fully characterized. Isolated yields of about 75% were obtained, and the products each possessed full potency in an in vitro rat pituitary bioassay and full receptor-binding affinity. Methods to monitor the amidation of polypeptide substrates and analyze the final products are described, including the use of capillary zone electrophoresis. A transient alpha-hydroxyglycine intermediate, [Ala15]-GRF(1-29)-Gly(alpha-OH)-OH, was isolated and characterized. Kinetic studies with this intermediate demonstrate that the rat alpha-amidating enzyme from recombinant mouse C127 cells possesses both the monooxygenase and lyase activities needed to catalyze both steps of the amidation process.

Amino Acid Sequence↗