Search PubMed⌕ Search

Biomedical subjects

H L Chan

Publications and source records attributed to H L Chan.

At least 73 records · Page 4Linked to original sources
PubMed1997

Time-frequency distribution of heart rate variability below 0.05 Hz by Wigner-Ville spectral analysis in congestive heart failure patients.

The Wigner-Ville spectral analysis was utilized to demonstrate a high-resolution time-frequency distribution of heart rate variability below 0.05 Hz. There are different time-frequency characteristics between the normal subject and the patient with severe congestive heart failure. The former consists of multiple and broad-band spectral peaks, while the latter presents unique spectral peaks. Based on Bayes theory, a classifier for the unique spectral peaks was developed. After the beneficial improvement with low-dose beta-blockers, the unique spectral peaks had disappeared or the time of occurrence was reduced in most patients.

Adrenergic beta-Antagonists↗
PubMed1997

Simultaneous occurrence of papulonecrotic tuberculide and erythema induratum and the identification of Mycobacterium tuberculosis DNA by polymerase chain reaction.

The simultaneous occurrence of two tuberculides in one patient is rare. We report the case of a 32-year-old man presenting with both papulonecrotic tuberculide and erythema induratum. Mycobacterial DNA was identified from both skin lesions by polymerase chain reaction using formalin-fixed and paraffin-embedded tissues, suggesting that tuberculides are related to tuberculosis. New skin lesions developed after the patient discontinued his medication on his own initiative, 2 months after triple antituberculous therapy had been started. It is important to continue therapy for a prolonged period.

Adult↗
PubMed1997

Time-frequency spectral analysis of heart rate variability during induction of general anaesthesia.

We have examined the spectral components of heart rate variability (HRV) during induction of anaesthesia with thiopentone, tracheal intubation and subsequent inhalation of isoflurane-nitrous oxide. Commonly used spectral analysis methods such as fast Fourier transformation or autoregressive modelling require stationary data and are not suitable for the rapidly changing HRV data in this period. An advanced spectral analysis method, time-frequency analysis, which can treat non-stationary data, was used in this study. Multiple spectra were generated to demonstrate the time-related spectral components of HRV. Mid-frequency power (MF, 0.08-0.15 Hz), high-frequency power (HF, 0.15-0.5 Hz) and MF/HF ratio at baseline, after induction (before intubation), immediately after intubation and during maintenance periods were calculated and compared. MF and HF powers decreased after induction and were reduced further in the maintenance period but MF/HF ratio remained unchanged after induction. Immediately after intubation MF and HF powers did not differ significantly from the immediate pre-intubation values, but MF/HF ratio did.

Adult↗
PubMed1997

Cutaneous involvement in polyvinylpyrrolidone storage disease: a clinicopathologic study of five patients, including two patients with severe anemia.

Polyvinylpyrrolidone (PVP), formerly a plasma expander, has continued to be inappropriately used in Taiwan for intravenous injection as a "blood tonic." Five cases of PVP storage disease with cutaneous involvement were studied. Two patients presented with cutaneous eruptions mimicking collagen vascular disease and chronic pigmented purpuric dermatosis. Two other cases were found incidentally: one was with a metastatic tumor and the other in a pemphigus lesion. The fifth case was seen in a blind skin biopsy specimen taken to exclude Niemann-Pick disease after hematologic examination of a bone marrow smear. The latter patient and the patient with a collagen vascularlike disease also had severe anemia and serious orthopedic and neurologic complications due to massive infiltration of PVP-containing cells in the bone marrow with destruction of the bone. Severe irreversible anemia due to PVP storage disease has not been reported before. Three patients admitted having a history of receiving intravenous injection of PVP. The samples obtained from two of them indeed contained 5% PVP as determined by chemical analysis. PVP storage disease can be diagnosed by its histopathologic features. The skin biopsy specimens all showed a variable number of characteristic blue-gray vacuolated cells around blood vessels and adnexal structures with positive tinctorial reactions to mucicarmine, colloidal iron, and alkaline Congo red and negative to periodic acid-Schiff (PAS) and alcian blue. The PVP storage cells were shown to be CD68+ macrophages. The presence of PVP in the skin induced little or no inflammatory reaction. Only the pelvic mass in one patient had a foreign body granuloma formation. Our study showed that systemic parenteral administration of PVP preparation could result in the accumulation of PVP storage cells in the skin, with or without clinical eruptions. The diagnosis of systemic PVP storage disease can be established by performing a skin biopsy for pathologic study. It is important for pathologists and clinicians to be aware of this iatrogenic storage disease to avoid misdiagnosis for hereditary storage disease, osteomyelitis, or signet-ring cell carcinoma. Serious hematologic and orthopedic complications can be caused by repeated massive intravenous injection of PVP. Therefore, PVP preparations should be strictly prohibited for systemic administration.

Adult↗
PubMed1997

Elimination of interference component in Wigner-Ville distribution for the signal with 1/f spectral characteristic.

A new technique for interference-term suppression in Wigner-Ville distribution (WVD) is proposed for the signal with 1/f spectrum shape. The spectral characteristic of the signal is altered by f alpha filtering before time-frequency analysis and compensated after analysis. With the utilization of the proposed technique in smoothed pseudo Wigner-Ville distribution, an excellent suppression of interference component can be achieved.

Heart Rate↗
PubMed1997

The effect of glycolic acid on the treatment of acne in Asian skin.

BACKGROUND: Glycolic acid has become important and popular for treating acne. OBJECTIVE: To evaluate the efficacy and safety of serial glycolic acid peels with glycolic acid home care products on facial acne lesions and other associated skin problems. METHODS: We collected 40 Asian candidates with moderate to moderately severe acne. They were divided into two groups according to the degree of greasiness of their facial skin. The two groups' members were treated with four series of 35% and 50% glycolic acid peels, respectively. They also used 15% glycolic acid home care products during this study period. The improvement of acne as well as other associated problems were assessed by both the physicians and the patient themselves. RESULTS: Significant resolution of comedones, papules, and pustules was found. The skin texture of each candidate was dramatically rejuvenated. Consistent and repetitive treatment with glycolic acid was needed for the apparent improvement of acne scars and cystic lesions. The follicular pores also became comparatively smaller. Furthermore, most of the candidates had much brighter and lighter looking skin. Only small percentage of patients (5.6%) developed side effects. CONCLUSION: Glycolic acid has considerable therapeutic value for acne with minimal side effects even in Asian skin. It may be an ideal adjunctive treatment of acne.

Acne Vulgaris↗
PubMed1996

Sequestration of mitotic (M-phase) chromosomes in autophagosomes: mitotic programmed cell death in human Chang liver cells induced by an OH* burst from vanadyl(4).

BACKGROUND: Fragmentation of genomic DNA in apoptosis/programmed cell death (PCD) is a characteristic hallmark in which both 2N and 4N DNA from G1, S, and G2/M cell cycle phases were seen degraded to the sub-2N Ao level in PCD such as from serum deprivation, glucocorticoid treatment, and gamma-radiation. However M-phase (mitotic) cells are said to perish only via non-programmed or necrotic cell death unless they were allowed to complete cytokinesis and re-enter interphase. The morphological criteria of PCD refer only to interphase cells with intact nuclear membranes, none seems applied to mitotic cells. We show here autophagic sequestration of mitotic chromosomes in a typical PCD response where G1, S, and G2/M DNA were replaced by a sub-2N Ao peak, suggesting that mitotic cells may yet have the option of PCD or suicide. Autophagy is absent in necrosis. METHODS: Mitotic human Chang liver cells in normal monolayer culture were compared with apoptotic counterparts initiated by a burst of hydroxyl free radicals (OH*) generated from vanadium internalized by an NH4Cl prepulse containing vanadyl(4) ions. Total (free and bound) vanadium uptake was quantitated by elemental spectral analysis of single cells using a) Particle-Induced X-ray Emission (PIXE) profiling, and b) Scanning Transmission Ion Microscopy (STIM) in the nuclear microscope. The Coulter EPICS PROFILE II flow cytometer was used for a) the cell cycle analysis using propidium iodide-DNA binding, b) intracellular pH (pHi) evaluation in the acidification-and-recovery cycle, using ratiometric 2',7'-bis(2-carboxyethyl)-5 (and-6)-carboxyfluorescein (BCECF) fluorescence quantitation. Transmission electron microscopy examined the morphological changes. Vanadyl(4)- generated hydroxyl free radicals (OH*) were evaluated by measuring OH*-benzoic adduct fluorescence at 304/413 nm using the SPEX Fluoromax photon counting spectrofluorometer. RESULTS: Nuclear microscopy showed that a 30 min acidification prepulse containing 4mM vanadyl(4) ions, V(4), had increased the total (free and bound) vanadium concentration of human Chang liver cells from normal ultratrace levels to 56,992 ppm of dry wt (1.1174 Eq per kg dry wt). After the prepulse, cells realkalinized in DMEM growth medium, recovering to the physiological pHi level in 30 min. At the physiological pH 7 level, V(4) generated a burst of OH* free radicals in the order of 15,000 folds above the prepulse (pH 4.5) level. In these conditions, spectrofluorometric evaluation showed loss of DNA intercalation with propidium iodide (PI-DNA binding) indicating DNA degradation. Cell-by-cell evaluation of the PI-DNA binding by flow cytometry showed abolition of G1, S, and G2/M phases and their replacement by a sub-2N Ao peak of fragmented DNA, emulating serum deprivation PCD in these cells. Immediately upon initiating an OH* burst ultrastructural profiles showed mitotic chromosomes (M-phase chromatin) being surrounded by rough endoplasmic reticulum (RER) and small vesicles, indicating their sequestration in autophagosomes. Autophagy was also seen to be a prominent feature in serum deprivation PCD. CONCLUSION: Sequestration of mitotic chromosomes by autophagosomes in a typical PCD response showed a well-defined morphological pathway for direct degradation of M-phase chromatin without first completing cytokinesis. Mitotic cells could commit suicide via autophagy directed at its own chromatin. Autophagic sequestration of chromatin in PCD is novel.

Apoptosis↗
PubMed1996

Acquired generalized hypohidrosis/anhidrosis with subclinical Sjögren's syndrome: report of a case with diffuse syringolymphoid hyperplasia and lymphocytic sialadenitis.

The pathogenesis and the underlying pathologic changes of acquired generalized hypohidrosis/anhidrosis (AGHA) are largely unknown. We studied a case of AGHA in a young woman suffering from heat intolerance and progressive loss of sweating. Pathologic study of affected skin revealed unique syringolymphoid hyperplasia with T cell infiltration, suggesting a T cell-mediated autoimmune disease. The patient also had subclinical Sjögren's syndrome and diffuse hair loss. The pathogenesis of the latter two conditions is believed to be related to the patient's AGHA.

Adult↗
PubMed1995

Clear cell papulosis: report of three cases of a newly recognized disease.

BACKGROUND: Clear cell papulosis is a newly described disease. Since the first report in 1987, no other cases have been reported. OBJECTIVE: Our purpose was to describe three more newly identified cases that further characterize this disease. METHODS: Formalin-fixed and paraffin-embedded biopsy specimens were used for histochemical and immunohistochemical studies. RESULTS: The three patients included two boys and, for the first time, a girl. All three had multiple white papules on the lower part of the abdomen, with or without scattered lesions along the milk lines bilaterally. The main histopathologic finding was the presence of clear cells scattered mainly among the basal cells of the acanthotic epidermis. The clear cells were variably stained by mucicarmine, colloidal iron, alcian blue (pH 2.5), periodic acid-Schiff, the anticytokeratin antibody AE1, carcinoembryonic antigen, epithelial membrane antigen, and gross cystic disease fluid protein-15. CONCLUSION: Clear cell papulosis is a unique clinicopathologic entity. The clear cells were confirmed to be sweat gland secretory cells by their positive immunostaining with gross cystic disease fluid protein-15. The latter was also present in eccrine sweat gland coil cells. However, whether the clear cells were eccrine or apocrine secretory cells could not be determined.

Biopsy↗
PubMed1995

Aluminum oxide crystal microdermabrasion. A new technique for treating facial scarring.

BACKGROUND: Aluminum oxide crystal microdermabrasion, a newly developed technique, has the advantages of less bleeding, fewer complications, better compliance, and no need for local anesthesia or high surgical skill in comparison with traditional dermabrasion. OBJECTIVE: To demonstrate the effectiveness of this new technique in the treatment of facial scarring. METHODS: A total of 41 patients were treated by this technique during the past 2 years (July 1992 to June 1994). RESULTS: All patients treated had good to excellent clinical improvement with 9.10 mean treatment sessions. CONCLUSION: From our experience and results, we think aluminum oxide crystal microdermabrasion is a safe surgical procedure and will be a good supplement to traditional dermabrasion especially in this era of HIV infection.

Acne Vulgaris↗
PubMed1994

Cutaneous manifestations of non-01 Vibrio cholerae septicemia with gastroenteritis and meningitis.

A 58-year-old man with diabetes had fever and chills 5 days after ingestion of raw seafood. Nausea, vomiting, watery diarrhea, bilateral calf pain, and neck stiffness subsequently developed. Generalized edema and ecchymotic patches with a vesiculobullous eruption appeared on the extremities. Four blood cultures were positive for Vibrio cholerae non-01. The patient was successfully treated with antibiotics. This is the first documented case of V. cholerae non-01 septicemia with cutaneous lesions and meningitis in Taiwan.

Bacteremia↗
PubMed1994

Ossifying dermatofibroma with osteoclast-like giant cells.

Dermatofibroma or cutaneous fibrous histiocytoma is a common cutaneous tumor. Rare histologic variants have been described. We report another variant of dermatofibroma characterized by osteoclast-like giant cells with metaplastic bone formation. Clinically the lesion was a small, brown, hard papule of several months' duration on the left anterior leg of a 58-year-old woman.

Female↗
PubMed1994

Anticentromere antibodies (ACA): clinical distribution and disease specificity.

Sera from 3528 patients with autoimmune disease, and non-autoimmune disease, and 500 normal individuals were studied for the presence of anticentromere antibodies (ACA) by indirect immunofluorescence on HEP-2 cells. Sixty-seven specimens were identified showing discrete speckled staining: 55 (82.1%), 11 (16.4%), and one (1.5%), were from patients with autoimmune disease, non-autoimmune disease and normal control subjects, respectively. These ACA were present frequently in CREST syndrome (55%), Raynaud's disease (29.6%) and primary biliary cirrhosis (30%). Only 16.4% of the antibody positive patients carried a clinical diagnosis of CREST, which means that ACA are not specific for CREST syndrome. High antibody titre persisted irrespective of whether or not the patients had active disease. The ACA were present infrequently in Sjögren's syndrome, systemic lupus erythematosus, rheumatoid arthritis, immune thrombocytopenic purpura, Graves' disease, immune haemolytic anaemia, and vitiligo. Sera from 107 patients with various other autoimmune diseases were negative for ACA.

Autoantibodies↗