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Biomedical subjects

S N Chang

Publications and source records attributed to S N Chang.

35 records · Page 2Linked to original sources
PubMed1996

Minocycline treatment for confluent and reticulated papillomatosis.

We report six cases of confluent and reticulated papillomatosis in which the skin lesions cleared almost completely after treatment with minocycline. Patients with confluent and reticulated papillomatosis often do not respond well to a variety of therapeutic agents. The response of confluent and reticulated papillomatosis to minocycline was first described in 1965. Although the pharmacologic mechanisms of minocycline in confluent and reticulated papillomatosis are unknown, we suggest that it should be considered as a first-choice therapeutic agent because of its marked effectiveness.

Adolescent↗
PubMed1995

Focal acantholytic dyskeratosis on the lip.

A case of focal acantholytic dyskeratosis (FAD) in a 55-year-old woman is reported. The lesion was located on the lip and manifested as a painful, oozing, crusted patch lasting for 20 years. Although FAD has been recently reported in the mucosa of the anal canal without cutaneous lesion, we report a case of FAD that appeared on the lip with clinical manifestation.

Acantholysis↗
PubMed1995

Seroreversion of the serological tests for syphilis in the newborns born to treated syphilitic mothers.

BACKGROUND: IgG antibodies from mothers adequately treated for syphilis can cross the placenta and appear in the sera of healthy newborns without infection. In such infants, a false diagnosis of congenital syphilis is often made. We have designed a retrospective survey to determine the time of seroreversion of the serological tests for syphilis (STS) in uninfected newborns born to mothers who were adequately treated for syphilis. MATERIALS AND METHODS: Fifty two seropositive, untreated newborns born to 51 mothers treated for syphilis were studied. The newborns were followed at 1, 3, 6, 9, and 12 months of age until seroreversion was detected. The VDRL test was followed until 12 months in 12 of the 22 newborns who were positive at birth, the TPHA in 21 of the 46 newborns, and the FTA-ABS test in 22 of the 48 newborns. RESULTS: In the first serological tests done within 1 month after birth, the VDRL was positive in 22 newborns (42%), the TPHA in 46 (88%), and FTA-ABS in 48 (92%). The VDRL seroreverted within 6 months after birth in 84%, and within 1 year in 100%. The TPHA test seroreverted in 95% within 1 year after birth. The FTA-ABS test seroreverted in 100% within 1 year after birth. CONCLUSIONS: In most seropositive, untreated newborns born to treated mothers the VDRL became negative within 6 months after birth and the TPHA and FTA-ABS within 1 year. This result is consistent with current Centers for Disease Control (CDC) guidelines. However, although the CDC guidelines are adequate in general, we think that some revision is desirable concerning the IgM test and combination of the test results in order to rule out congenital syphilis in seropositive, nonsymptomatic newborns born to the treated mothers.

Female↗
PubMed1994

Cutaneous mesenchymal hamartoma.

A case of a cutaneous mesenchymal hamartoma occurring on the thigh of a newborn infant is reported. Microscopically, the solitary tumorous lesion consisted of an intimate mixture of fibrocollagenous bundles, islands of mature fat cells, distorted blood vessels, and eccrine sweat glands. Many mast cells were scattered throughout the fibrocollagenous bundles. Ultrastructurally, most tumor cells were suggestive of undifferentiated mesenchymal cells.

Hamartoma↗
PubMed1994

Clinical analysis of 40 cases of childhood-onset Behçet's disease.

Behçet's disease is a chronic, relapsing, idiopathic, multi-system condition characterized by mucocutaneous, ocular, gastrointestinal, articular, vascular, urogenital, and neurologic involvement. Usually the onset occurs between 20 and 30 years of age; it is very uncommon in children. We analyzed 40 cases of childhood-onset Behçet's disease. The male:female ratio was 0.67. The most frequent major sign was oral ulceration, appearing in all patients. Other major signs were genital ulcers (33 patients), skin lesions (29), and ocular lesions (11). The average time interval between the initial oral ulceration and the second major manifestation was 8.8 years. After the second major manifestation, the third and fourth features rapidly developed within one to two years. The most frequent minor sign was arthritis, occurring in 11 of 40 patients. Intestinal, neurologic, and renal involvement was also present. From our results, we concluded that oral ulceration, which is the most common initial manifestation, should not be neglected in children, since it may signal Behçet's disease.

Age of Onset↗
PubMed1989

A diffusive sampler for personal monitoring of toluene diisocyanate (TDI) exposure; Part I: Design of the dosimeter.

A passive dosimeter for monitoring occupational exposure to toluene diisocyanate (TDI) was developed. The device is constructed from a 37-mm aerosol cassette. The collection medium used in the dosimeter is 0.5% sulfuric acid (H2SO4). Membranes of both the permeation and diffusion types were evaluated for use in the dosimeter. Microporous Teflon diffusion membranes exhibited superior performance in terms of surface effects and residual TDI and were chosen for use. Collected TDI is determined as toluenediamine by either colorimetry using a modification of the Marcali technique or fluorometry using fluorescamine reagent. A significant dependence on wind speed was minimized by use of a second microporous membrane as a wind screen. The mass transfer rate of TDI was found to be approximately 0.0152 micrograms/ppb.hr and was equivalent for the 2,4 and 2,6 isomers of TDI.

Air Pollutants, Occupational↗
PubMed1989

A diffusive sampler for personal monitoring of toluene diisocyanate (TDI) exposure; Part II: Laboratory and field evaluation of the dosimeter.

A passive monitor for TDI which utilizes microporous Teflon diffusion membranes and a 0.5% sulfuric acid (H2SO4) absorbing medium was evaluated. The collection rate of TDI is proportional to exposure dose from 10 to at least 300 ppb.hr, and response is equivalent for 2,4- and 2,6-TDI. Collection rate is independent of humidity and normal atmospheric pressure variations, while temperature causes a decrease of 1.0% per degree centigrade. Negative interference caused by ambient nitrogen dioxide (NO2) is eliminated by addition of sulfamic acid (HSO3 NH2) to the collecting medium. N-ethylmorpholine is a positive interferent. Field testing of the sampler against a reference impinger technique indicated a positive bias when TDI is aerosolized.

Air Pollutants, Occupational↗
PubMed1987

Inactivated Saccharomyces cerevisiae as virulence-enhancing agent in the toxicity test of Salmonella typhi and the immunity assay of typhoid vaccine in mice.

Mucin has been used as virulence-enhancing (VE) agent in estimation of the toxicity of bacteria to mice and the potency of bacterial vaccines such as typhoid vaccine. Discontinuance of the acceptable brand of mucin made it necessary to search for an effective alternative. Five percent inactivated Saccharomyces cerevisiae (IY) showed a significant higher VE effect on S. typhi in mice (132 colony forming units/LD50) with lower viscosity when compared to 5% mucin (740 colony forming units/LD50), and either one could promote bacterial lethal toxicity in mice more than 10(4) times. The strong correlation (r2 = 0.9765) between the immune dose and the ratio of mouse death was found by using 5% IY as VE agent in the active mouse protection test for typhoid vaccine. The relative potencies of a typhoid vaccine to the reference vaccine obtained by using 5% mucin or 5% IY as VE agent were not significant difference. Therefore, IY was a suitable substitute for mucin as a VE agent in the toxicity test of bacteria and in the immunity assay of typhoid vaccines.

Animals↗
PubMed1986

[Comparison of plaque reduction and active mouse protection tests for estimating the potency of Japanese encephalitis vaccine].

The plaque reduction test for assaying the potency of Japanese encephalitis vaccine was evaluated by comparing with the active mouse protection test. The relative potency of tested vaccine to the standard vaccine were 1.40 +/- 0.250 by the plaque reduction test with coefficient variation of 0.179 and 2.54 +/- 1.152 by the active mouse protection test with coefficient variation of 0.454. There was no significant difference between the plaque reduction and the active mouse protection test in term of relative potency, but the plaque reduction method had a better reproducibility. Furthermore, the plaque reduction method showed a higher sensitivity and time saving.

Animals↗
PubMed1982

Determination of airborne 2,4-toluenediisocyanate vapors.

An accurate and convenient sampling and analytical method was developed for airborne 2,4-toluenediisocyanate (TDI). A chromophoric derivatizing reagent was used to convert the TDI to a stable urea derivative during collection for subsequent quantification by liquid chromatography. The overall accuracy (at the 95% confidence level) and precision of the method are +/- 7.9% and +/- 10.0% respectively under laboratory conditions. Long term stability was observed for both the reagent coated sorbent tube and the TDI urea derivative. A TDI concentration of 1 ppb can be detected by taking a 15-1 sample volume.

Air↗
PubMedDate not supplied

Health effects from indoor air pollution: case studies.

In recent years there has been a growing awareness of the health effects associated with the presence of contaminants in indoor air. Numerous agents can accumulate in public buildings, homes and automobiles as a result of ongoing activities that normally occur in these closed spaces. Ventilation is a major factor in the control of indoor air pollutants since proper movement of air can prevent or minimize the build up of compounds in buildings. The recent emphasis on energy conservation has lead to measures which economize on energy for heating and air conditioning, but which also trap pollutants within a building. Three cases of indoor air pollution were investigated. A typical investigation of indoor air pollutant problems includes the following: interviews with building occupants; history of the building with regard to maintenance, pesticide treatment, etc.; a survey of the building and ventilation; and when warranted, sampling and analysis of air. Each case presented is unique in that atypical situations caused agents to accumulate in a building or section of a building. The indoor air problems in these cases were solved by identifying and removing the source of the offending agent and/or improving the ventilation in the building.

Adhesives↗
PubMedDate not supplied

Assessing asbestos exposure potential in nonindustrial settings.

The presence of asbestos containing materials (ACM) in office and commercial buildings is a significant environmental problem. Asbestosis, mesothelioma and lung cancer have been linked with industrial exposure to airborne asbestos. The extensive use of asbestos products in buildings has raised concerns about the widespread exposure of the general public to asbestos in nonoccupational settings. The presence of asbestos in a building does not necessarily mean that significant exposure of the occupants of the building has occurred, but it is important that the asbestos be monitored regularly to ensure that fibers do not become airborne. If ACM are contained within a matrix and not disturbed, exposure is unlikely. However, if the asbestos becomes friable (crumbling) or if building maintenance, repair, renovation or other activities disturb ACM, airborne asbestos fibers may be a source of exposure to the occupants of the building. Currently, asbestos exposure assessment is conducted by a phase contrast light microscope (PCM) technique. Due to its inherent limitation in resolution and the generic counting rules used, analysis by the PCM method underestimates the airborne asbestos fiber concentration as compared to analysis by transmission electron microscopy (TEM). It is important that the air monitoring results analyzed by PCM be interpreted carefully in conjunction with a survey by a professional to judge the physical condition of the ACM in buildings. Exposure levels to airborne asbestos fibers vary from day to day and depend on the physical condition of the material involved and the type of operating and maintenance program in place.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollution↗
PubMedDate not supplied

Generalized eruptive histiocytoma: a pediatric case.

Generalized eruptive histiocytoma (GEH) is a rare, benign, papular, self-healing histiocytosis characterized by recurrent crops of small, firm, tan to reddish papules that appear in a symmetrical fashion on the face, trunk and arms, affecting mainly adults. Approximately 31 cases have been described, of which 8 were in children. A new concept unifying the confusing potpourri of non-Langerhans cell histiocytosis has recently been described in which GEH has been considered to represent an early undifferentiated stage of various histiocytic disorders. We describe a 9-year-old boy who had all the features of GEH and emphasize the importance of clinical, histologic, immunohistochemical, and ultrastructural examination in the diagnosis of histiocytic disorders. On the basis of the increasing numbers of similar reported cases showing overlap in clinical and histologic features and in accordance with the new unifying concept of non-Langerhans cell histiocytosis, we presume that this group of disorders may represent a continuous spectrum of a single disease rather than a collection of separate disorders.

Antigens, CD↗