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Biomedical subjects

R C Yu

Publications and source records attributed to R C Yu.

At least 37 records · Page 2Linked to original sources
PubMed1997

A lung retention model based on Michaelis-Menten-like kinetics.

A Michaelis-Menten (MM)-like kinetic model for pulmonary clearance and retention of insoluble dusts was developed and validated by comparing our predictions with experimental data from F344 rats. Published data from inhalation studies involving accumulation and elimination of photocopy test toner, antimony trioxide, carbon black, and diesel exhaust particles were investigated. Numerical integration techniques were used to solve mass balance relationships based upon dust retention in a single lung compartment and clearance via an MM-like kinetic process. The model fit most of the experimental data well. The parameters of MM-like clearance kinetics, which had been derived strictly from the elimination phase, accurately predicted dust retention during the elimination as well as accumulation phases. Furthermore, parameters estimated from one study could accurately predict retention of the same dust in other studies. Particle density and gender of the animals had no effect on the goodness of fit of model predictions. This study suggests that MM-like kinetics offer a reasonable description of particle clearance from the pulmonary region of the rat lung that is more parsimonious than existing particle-clearance models and therefore more suitable for use with small amounts of data.

Air Pollutants↗
PubMed1996

The relationships between urinary elimination, airborne concentration, and radioactive hand contamination for workers exposed to uranium.

The purposes of this study were to estimate the proportional contribution of uranium dust exposure to urinary excretion of the metal, and to examine the influence of hand contamination on the elimination of uranium from the urine of workers who performed different jobs. The study was based on records taken from a gaseous diffusion plant in 1956. Regression techniques were used to investigate the relationship between uranium concentration in urine and exposure variables, including the concentration of uranium dust and the incidence of hand contamination. The proportional contribution of airborne to urinary uranium was estimated by the slope of this relationship. It is concluded that the workers eliminated uranium at relatively constant rates per unit air concentration (0.67 to 1.27 micrograms/L per micrograms/m3). In addition to airborne uranium, hand contamination significantly contributed to the elimination among maintenance crew, but not among production workers. Furthermore, the production index was shown to be a useful surrogate for airborne and urinary uranium.

Air Pollutants, Occupational↗
PubMed1996

A rapid polymerase chain reaction-based technique for detecting clonal T-cell receptor gene rearrangements in cutaneous T-cell lymphomas of both the alpha beta and gamma delta varieties.

T-cell receptor-gamma gene rearrangements provide specific clonal markers for a variety of lymphoid malignancies. T-cell receptor gene rearrangements in patients with cutaneous T-cell lymphoma were examined using conventional Southern blot analysis and a newly developed polymerase chain reaction (PCR)-based technique. The oligoprimers amplified a rearranged V gamma and J gamma segment (including the N region) of the T-cell receptor-gamma gene, and products were resolved using high-resolution nondenaturing polyacrylamide gel electrophoresis. Our results demonstrated concordance between the two techniques in 10 patients with cutaneous T-cell lymphomas (including nine cases of C beta and one case of delta 2 TCR gene rearrangements) and 10 negative controls. In the present study, we have shown that this PCR-based method provides a highly sensitive, specific technique for the detection of T-cell clones of both the alpha beta and gamma delta varieties and could be used in both fresh and formalin-fixed, paraffin-embedded tissues. It is estimated that this PCR-based technique is 10 to 50 times more sensitive than conventional Southern blot analysis in the detection of small T-cell clones.

Base Sequence↗
PubMed1996

Relation between pulmonary clearance and particle burden: a Michaelis-Menten-like kinetic model.

OBJECTIVES: To test the validity of a Michaelis-Menten-like kinetic model of pulmonary clearance of insoluble dusts. METHODS: Data were investigated from studies of pulmonary clearance in F344 rats exposed to antimony trioxide (Sb2O3), photocopy test toner, polyvinyl chloride powder (PVC), and diesel exhaust particles. The Michaelis-Menten-like model was used to develop a relation in which the pulmonary clearance half time was a linear function of lung burden. After combining all data, linear regression techniques were applied to investigate the underlying relations. With the estimated intercepts and slopes, the Michaelis-Menten-like kinetic parameters kmax (maximal clearance rate) and m1/2 (a characteristic lung burden at which kmax is reduced by 50%) were derived for the four dusts. RESULTS: The experimental data fit the linear regression very well (R2 = 0.989), suggesting that pulmonary clearance for the four dusts followed Michaelis-Menten-like kinetics. Values of the intercept terms were not significantly different among the four dusts (P = 0.294), indicating that the intrinsic clearance rates of F344 rats were the same among the four experiments. The intrinsic clearance half time was estimated to be 77.8 days, leading to an estimated kmax of 0.0089 day-1. However, the slopes of the linear relations were significantly different among the four dusts (P < 0.001). Values of m1/2 were ranked in the order of: Sb2O3 (0.69 mg) < photocopy test toner (0.97 mg) < diesel exhaust (2.49 mg) congruent to PVC (2.90 mg). CONCLUSION: This study suggests that the Michaelis-Menten-like kinetic model reasonably describes the kinetic behavior of pulmonary clearance in F344 rats. The parameters m1/2 can be used to differentiate the potency of a particular dust for impairing pulmonary clearance.

Air Pollutants↗
PubMed1996

Tumour progression in a patient with granulomatous mycosis fungoides.

We report a patient with granulomatous mycosis fungoides whose disease transformed into a high grade blast lymphoma with angiocentric features within 12 months of the initial diagnosis. This repudiates previous claims that granulomatous inflammation is protective in cutaneous T-cell lymphoma.

Disease Progression↗
PubMed1996

Strict anatomical coexistence of vitiligo and psoriasis vulgaris--a Koebner phenomenon?

We describe a patient who developed typical psoriatic plaques covering completely or partly the vitiliginous areas of her skin. Her psoriasis was strictly limited to the vitiliginous patches with no involvement of the normal skin. Strict anatomical coexistence of both diseases is extremely rare and suggests a causal mechanism, possibly due to a Koebner phenomenon, but genetic and environmental factors may also be involved.

Aged↗
PubMed1996

Langerhans cell histiocytosis--clinicopathological reappraisal and human leucocyte antigen association.

We have examined the clinicopathological correlates of 74 patients with histologically confirmed Langerhans cell histiocytosis. Factors that influenced disease outcome included, three or more organ/systems being involved, a disease onset before the age of 2 years, the involvement of certain vital organs/systems such as liver/spleen, bone marrow and lungs, and male gender. The total number of involved organs/systems was the single most important determinant of disease outcome. Mortality rate in patients with three or more organs/systems involved, was 26%, as compared with 0% in the group with one or two organs/systems involved (chi 2 = 11.2, P = 0.008). There were no familial cases in our series, but we looked for a possible immunogenetic association by tissue typing 46 Caucasian sufferers and comparing the results with 117 controls. We used normal peripheral blood lymphocytes in 39 cases, Epstein-Barr virus-transformed lymphoblastoid cell lines in 12 cases, and both peripheral blood and Epstein-Barr virus-transformed lymphocytes in five cases. The HLA-B7 antigen was significantly increased Langerhans cell histiocytosis patients (19 of 46 = 41.3%) compared with 19 of 117 (16.2%) in the control group chi 2 = 11.2, relative risk = 3.6, P value after correction = 0.013). Attempt to stratify the disease into single-system or multisystem disease did not result in any significant association.

Adolescent↗
PubMed1995

Lack of T-cell receptor gene rearrangements in cells involved in Langerhans cell histiocytosis.

BACKGROUND: Studies using X-chromosome inactivation assays have recently provided evidence in support of a clonal origin of cells affected by Langerhans cell histiocytosis (LCH). A search for more specific clonal markers has led to the investigation for T-cell receptor (TCR) gene rearrangements in cells affected by LCH. METHODS: Conventional southern blot analysis was used to investigate the possibility of clonal TCR gene rearrangements in tissues affected by LCH wherever possible, otherwise, a polymerase chain reaction (PCR)-based technique was employed for amplification of rearranged joint (J) and variable (V) segments of the TCR-gamma gene including the N-region. 32P-labeled PCR products were then resolved using nondenaturing polyacrylamide gel electrophoresis. RESULTS: The results using the PCR-based technique showed a lack of clonal rearrangement of the TCR-gamma gene in affected tissues of eight patients with different stages of LCH. Southern blot analyses performed on two of these samples confirmed germline configurations at both the TCR-C-beta and delta-2 gene loci. CONCLUSIONS: There is no evidence of clonal TCR gene rearrangement in cells involved by LCH. The search for a more specific clonal marker to address whether "'LCH cells" represent a neoplastic clonal transformation of cells with differentiation toward Langerhans cell phenotype continues.

Base Sequence↗
PubMed1995

Functional defect in cells involved in Langerhans cell histiocytosis.

The characteristic cell type involved in Langerhans cell histiocytosis, 'LCH cells', express most of the enzyme histochemical and immunocytochemical markers of normal epidermal Langerhans cells. It is not known, however, whether these LCH cells express the functional characteristics of normal epidermal Langerhans cells. We studied the alloantigen-presenting activity of LCH cells derived from lesional sites of three patients with the disease. Lesional cells expressing the CD1a molecule were enriched using either fluorescein-activated cell sorting or negative selection with indirect immunomagnetic beads, and functional activity was assessed using the 6-day primary allogeneic mixed-cell reaction. Compared to epidermal Langerhans cells from healthy controls, LCH cells showed minimal alloantigen-presenting activity on a per-cell basis. The diminished activity was not reversed by exogenous prostaglandin synthetase inhibitor or recombinant human IL-1 beta. This study confirms our previous report of a child, with fatal multisystem Langerhans cell histiocytosis suggesting that this disease represents a condition in which functionally defective cells of Langerhans cell phenotype accumulate and/or proliferate in various tissues. We postulate that the functional defect is a primary defect of these LCH cells that have acquired an as-yet-undetermined biological insult(s).

Adult↗
PubMed1995

Cold urticaria, raised IgE and HIV infection.

We present a patient with cold urticaria as an unusual and late cutaneous manifestation of acquired immunodeficiency syndrome. The severe CD4 cell depletion and markedly elevated serum IgE levels in our patient provide some insights into certain aspects of immune regulatory mechanisms.

Adult↗
PubMed1994

Angioimmunoblastic lymphadenopathy with dysproteinemia and dermal T-cell lymphoma.

BACKGROUND: T-cell receptor (TCR)-gamma gene rearrangements provide a specific clonal marker for T-cell malignancies of both the alpha beta and gamma delta varieties. A polymerase chain reaction (PCR)-based method was used in this study for investigation of clonal TCR-gamma gene rearrangements in a patient with a classical presentation of angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) that subsequently progressed into an indolent form of dermal T-cell lymphoma. METHODS: TCR gene rearrangements in patients with cutaneous T-cell lymphoma (CTCL) were examined using conventional Southern blot analysis and a newly developed PCR-based technique for clonal TCR gene rearrangements. The oligoprimers amplified rearranged V gamma and J gamma segments (including the N region) of the TCR-gamma gene, and PCR products were resolved using high resolution nondenaturing polyacrylamide gel electrophoresis. RESULTS: The authors' results demonstrated good correlation between the two techniques in 10 patients with CTCL (9 patients with C beta and 1 patient with delta 2 rearrangements) and 10 control subjects. The PCR-based technique allowed the authors to detect the presence of an identical T-cell clone in all skin nodules, but not in the original lymph node affected by AILD. CONCLUSIONS: This PCR-based method for detecting clonal TCR rearrangements is a highly sensitive and specific technique for detecting T-cell clones in fresh and paraffin embedded tissues. The presence of a T-cell clone in all skin nodules of this patient, but not in the original lymph node affected by AILD, confirms previous findings that in some cases of AILD, clonal T-cell expansion may not be detectable until a later stage of the disease.

Adult↗
PubMed1994

Clonal proliferation of Langerhans cells in Langerhans cell histiocytosis.

X-chromosome-inactivation assays can be used to assess clonality. We used such an assay at the human androgen-receptor gene locus in three female patients with histologically proven Langerhans cell histiocytosis. All patients were heterozygous for this locus. Cells bearing the Langerhans cell phenotype were purified from involved tissue after fluorescence-activated cell sorting with monoclonal antibodies against the CD1a complex. After HhaI digestion of DNA, these CD1a positive cells demonstrated a non-random X-chromosome-inactivation pattern, whereas CD1a negative cells in the same tissue showed a random pattern. Our data suggest that Langerhans cell histiocytosis represents a clonal proliferation of cells bearing the Langerhans cell phenotype.

Antibodies, Monoclonal↗
PubMed1994

Morphological and quantitative analyses of normal epidermal Langerhans cells using confocal scanning laser microscopy.

Confocal scanning laser microscopy (CSLM), when used in conjunction with computerized image processing systems, provides a powerful tool for morphological and quantitative analyses of biological tissues. In this study, normal human epidermal sheets were stained by an indirect immunofluorescence method using anti-CD1a monoclonal antibody. Positively stained epidermal Langerhans cells (LCs) were visualized using the Bio-Rad MRC-600 Confocal Imaging System. Images obtained from the confocal microscope were volumetrically rendered and quantitatively analysed using ANALYZE (Version 4.0) running on a Sun SPARC 2 Workstation. Normal epidermal LCs were shown to be large disc-like structures with five to nine long dendritic processes per cell, orientated with their flat surfaces parallel to the skin surface. LCs form a monolayer network of cells distributed evenly throughout the suprabasal layers of the epidermis, with no direct physical contact between dendritic processes. Mean LC density was estimated to be 582 per mm2 (95% confidence intervals, CI = 233-940), and mean cell volume was 612 microns3 (95% CI = 257-1020). LCs in sun-exposed sites were significantly lower in mean cell density, but larger in mean cell volume, than in covered sites. Mean surface area projected by LCs was estimated to be 26.8% (95% CI = 18.9-34.2), and this value did not show significant regional or individual variation. Our data support the notion that epidermal LCs are organized in such a way as to maximize their surface area for efficient trapping of antigens, and a reduction in LC density per unit area in sun-exposed sites is compensated for by an increase in the mean cell volume.

Cell Count↗
PubMed1994

[Study on advanced non-small cell lung cancer patients with Qi deficiency and blood stasis syndrome].

108 cases of advanced non-small cell lung cancer (NSCLC) with Qi deficiency and blood stasis syndrome (QDBS) had been studied in this paper. It has been found that: (1) QDBS existed commonly in 60.2% of NSCLC patients. (2) QDBS patients had lowered immune function and blood hypercoagulating function, as compared with healthy persons. (3) The abnormal change of immunological indexes such as TC subgroup. TXB2, 6-keto-PGF1 alpha, fibrinogen and plasmin activity as well as hemorheological indices are important pathophysiological manifestation of QDBS. Thus, the principle of supplementing Qi and activating blood circulation combined with reducing phlegm and resolving masses should be emphasized in future research.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

[Studies of guben quyu No I combined with chemotherapy in treating cancer].

UNLABELLED: Cancer patients with Qi-Deficiency and Blood Stasis (QDBS) syndrome were studied, and stress was put on the observation of the Guben Quyu No. I, which was used in combining with chemotherapy for synergistic effect and attenuation of toxicity. THE RESULTS: QDBS syndrome often existed in cancer patients, and chemotherapy exacerbate the occurrence rate of QDBS syndrome. QDBS syndrome is somehow related to immuno-deficiency and blood hypercoagulability, the method of Yiqi Huoxue (YQHX) which used to be combined with chemotherapy could not only reduce the toxic-side effects of chemotherapy, but also improve the cellular immune function and hemorheology. Since the cellular immuno-deficiency and blood hypercoagulability were associated with recurrence and metastasis of cancer. It is considered that the Guben Quyu No I possibly is to reduce the occurring of the above-mentioned consequences.

Adult↗
PubMed1993

Allopurinol-induced toxic pustuloderma.

We report the case of a 67-year-old man who developed a pustular eruption, fever, neutrophilia and eosinophilia, following a short course of allopurinol. Toxic pustuloderma is an uncommon form of generalized pustular eruption with several characteristic clinical and pathological features. A number of drugs have been incriminated, but to our knowledge this is the first reported case of toxic pustuloderma occurring after the administration of allopurinol.

Aged↗
PubMed1993

Molecular analysis of the gamma delta T-cell receptor repertoire in normal human skin and in Oriental cutaneous leishmaniasis.

The extent of diversity of the gamma delta T-cell receptor (TCR) in normal human skin and Oriental Cutaneous Leishmaniasis (OCL) was examined by molecular analysis of the variable (V) delta gene segment, junctional (J) delta gene segment and junctional regions. To examine the expression of TCR delta genes, segments of gamma delta T lymphocytes, DNA isolated from normal human skin and from OCL were subjected to enzymatic gene amplification by the polymerase chain reaction (PCR) method using TCR V delta- and J delta-specific oligonucleotides as primers. PCR amplification using these primers indicated that the V delta 2 gene segment was predominantly used by gamma delta T lymphocytes in both normal human skin and OCL. To determine the extent of junctional diversity in the delta gene of gamma delta T cells in normal human skin and OCL, we sequenced the nucleic acid sequences corresponding to the V delta 2/J delta 1 junctional regions. Sequence analysis of junctional regions demonstrated broad junctional diversity in normal skin but only limited diversity in OCL. Our findings support the hypothesis that skin gamma delta T lymphocytes may derive from a fetal subset of gamma delta T lymphocytes that leaves the thymus early and colonizes the periphery. The limited junctional diversity demonstrated in OCL lesions indicates that gamma delta T cells can undergo oligoclonal expansion following recognition of a specific ligand and supports the idea that junctional regions are important in the recognition of antigenic determinant.

Amino Acid Sequence↗