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Biomedical subjects

W Fan

Publications and source records attributed to W Fan.

At least 145 records · Page 8Linked to original sources
PubMed1992

Clinical manifestations and prevalence of different types of supraventricular tachycardia among Chinese.

Sixty-nine cases of paroxysmal supraventricular tachycardia (PSVT) were submitted to electrophysiological studies. The prevalence of different types of PSVT is as follows: 49% of the cases had atrioventricular reentry tachycardia (AV-RT), 14.5% atrioventricular nodal reentry tachycardia (AVN-RT), 28% AV + AVN - RT, and 8.5% other types. Altogether 77% in this group had atrioventricular accessory pathway, of which half are concealed pathway. Electrocardiographic characteristics during tachycardia give hints to diagnosis: (1) AV - RT has the fastest heart rate, with 62% 200 BPM or more, and 82% more than 188 BPM; (2) retrograde P waves can be detected in 64% of cases with AV bypass; (3) 50% of AV - RT shows QRS of bundle branch block pattern. Since accessory pathways are present in the majority of PSVT patients in China, the importance of treatment is stressed.

China↗
PubMed1991

Eosin Y staining of proteins in polyacrylamide gels.

A staining method is described in which various proteins in polyacrylamide gels can be stained by using eosin Y. After a brief incubation of a polyacrylamide gel in an acidic solution of 1% eosin Y, various proteins, including human erythrocyte membrane sialoglycoproteins which are not detectable by Coomassie blue R-250 (CB), can be detected with a sensitivity of 10 ng protein. This is far more sensitive than CB staining and is comparable to the sensitivity of silver staining. In a Western blot, the antigenicity of an eosin Y stained protein is retained. In addition, proteins on an immunoblot sheet can be detected by eosin Y staining. The method described is rapid, sensitive, and reproducible with various proteins in polyacrylamide gels and has the added advantage of also staining sialoglycoproteins.

Acrylic Resins↗
PubMed1991

Age-related changes in the clinical and electrophysiologic characteristics of patients with Wolff-Parkinson-White syndrome: comparative study between young and elderly patients.

The natural history of patients with Wolff-Parkinson-White (WPW) syndrome remains an intriguing question with respect to clinical decision-making, since serial electrophysiologic data spread over several decades in the same patient are not available in the literature. To study the age-related changes in WPW syndrome, we compared two separate groups of patients referred to this Medical Center for electrophysiologic studies because of a clinical presentation with significant arrhythmias. An elderly group of 42 patients aged 50 years or more were compared with a younger group of 51 patients aged 15 to 30 years. The groups were comparable in terms of clinical presentation, including the number of patients who had reported syncopal episodes and those requiring cardioversion of their tachyarrhythmias. Baseline electrophysiologic variables such as sinus rate; sinoatrial conduction time; corrected sinus node recovery time; AH interval; and effective refractory periods of the right atrium, atrioventricular (AV) node, and right ventricular muscle, were significantly greater in the elderly group. Similarly, the anterograde effective refractory period of the bypass tract, the shortest atrial pacing cycle length with 1:1 anterograde conduction via the bypass tract, retrograde effective refractory period of the bypass tract, the shortest ventricular pacing cycle length with 1:1 retrograde conduction via the bypass tract, the shortest consecutive preexcited R-R interval during atrial fibrillation, and the cycle length of orthodromic atrial ventricular reciprocating tachycardia were significantly greater in the elderly group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Immunolocalization of transforming growth factor beta in rat molars.

A prominent cellular event in tooth eruption is the influx of mononuclear cells (monocytes?) into the dental follicle at the onset of eruption. In the mandibular first molar of the rat, this influx of cells reaches its peak at three days postnatally. Because transforming growth factor-beta 1 (TGF-beta 1) is chemotactic for monocytes, we used immunocytochemical methods to determine its localization in the rat molar during postnatal days 1-4 and day 7. The results indicate that TGF-beta 1 displays both a spatial and temporal localization in the rat molar. It is present in the stellate reticulum (SR) on days 1 and 2 postnatally but is absent in all the subsequent days examined. None of the other soft tissue layers-ameloblasts, stratum intermedium or dental follicle--immunostain for TGF-beta 1. This localization of TGF-beta 1 in the SR at a time that just precedes that influx of monocytes into the dental follicle, coupled with the fact that fenestrated capillaries are abundant in the follicle adjacent to the SR, suggests that TGF-beta 1 could play a role in attracting monocytes from the peripheral blood into the follicle.

Animals↗
PubMed1990

Ultrastructural and immunocytochemical characterization of cultured cells from rat molar stellate reticulum.

By scanning electron microscopy, the cultured cells were stellate and had numerous filipodia--characteristics of stellate reticulum cells in vivo. By transmission electron microscopy, they contained bundles of intermediate filaments, numerous mitochondria, large electron-dense granules and desmosomes--all features of the stellate reticulum in vivo. Moreover, the stellate reticulum was the only region of the enamel organ in vivo that contained large, electron-dense granules. By immunocytochemistry, the cultured cells contained cytokeratins, confirming their epithelial nature, and stellate reticulum cells in vivo and in vitro did not have an EGF receptor. Thus, these combined ultrastructural and immunocytochemical findings suggest that the cell culture was of stellate reticulum.

Alkaline Phosphatase↗
PubMed1990

Mold contamination of automobile air conditioner systems.

Eight cars belonging to patients who were found to have exacerbation of allergic rhinitis and bronchial asthma after turning on the air conditioner in their cars were examined. Mold concentrations inside the passenger compartment with the a/c turned off and at different climate control settings were lower than concentrations in the outside air. After turning on the air conditioner to "Max", cultures obtained at various intervals revealed that mold concentrations decreased significantly with time. Furthermore, placement of a filter at the portal of entry of outside air significantly reduced the mold concentration in the passenger compartment.

Air Conditioning↗
PubMed1989

Multiple thermolabile and temperature-sensitive lesions in mutant tl17 of vesicular stomatitis virus.

The vesicular stomatitis virus thermolabile mutant tl17 contains multiple lesions. The RNA-dependent RNA polymerase is temperature sensitive during primary transcription. The glycoprotein develops Endo H sensitivity more slowly at the nonpermissive temperature. Maturation or incorporation of the glycoprotein into progeny virions is also reduced. When virions of tl17 made at the permissive temperature are incubated in buffered medium at 39 degrees, their glycoprotein is cleaved, resulting in a product that resembles soluble glycoprotein. Compared to another glycoprotein mutant, ts 045, the glycoprotein of tl17 is only partially degraded to soluble G intracellularly and is more thermolabile. These properties of tl17 make it potentially useful for studies on glycoprotein synthesis, processing, and transport as well as for studies on pseudotype formation and viral maturation.

Animals↗
PubMed1989

Changes in the tartrate-resistant acid phosphatase cell population in dental follicles and bony crypts of rat molars during tooth eruption.

It was the aim of this study to determine the cellular changes that occur in the enamel organ, dental follicle, and surrounding bony crypt of the rat molar prior to and during tooth eruption. By use of light microscope histochemistry to detect cells containing tartrate-resistant acid phosphatase (TRAP), it was seen that TRAP-positive mononuclear cells were present in the dental follicle prior to the onset of eruption (e.g., three days postnatal age) and then declined in number during eruption. Concurrently, TRAP-positive osteoclasts were initially present in large numbers on the surface of the bony crypts surrounding the molars (three days postnatal age) and then declined in number as eruption progressed. Electron microscopy confirmed that these were mononuclear cells and osteoclasts. The results suggest that the mononuclear cells are either precursors of the osteoclasts or perhaps release cytokines that affect osteoclast formation or activity. Staining for alkaline phosphatase (ALP) activity indicated that at an early postnatal age (secretory stage of amelogenesis), ALP was detected only in the stratum intermedium of the enamel organ, whereas at a later age (maturation phase of amelogenesis), it was present only in the ameloblasts. These results, combined with a survey of the literature, strongly suggest that ALP moves from the base of the enamel organ to the enamel itself over a period of time ranging from pre- to post-eruption. Rat molars are teeth of limited eruption, and the cellular events that occur in eruption appear comparable with what is seen in dog and human dentition, especially in terms of the cellular events seen in the dental follicle prior to and during eruption.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1986

Imipenem-cilastatin in the treatment of methicillin-sensitive and methicillin-resistant Staphylococcus aureus infections.

Imipenem-cilastatin was evaluated for efficacy and toxicity as an antistaphylococcal agent in 23 patients; 11 of these patients were infected with methicillin-resistant Staphylococcus aureus (MRSA), and 12 were infected with methicillin-susceptible S. aureus (MSSA). There were 15 soft tissue, 5 endovascular, and 3 skeletal infections and a total of nine patients with bacteremia. As determined by in vitro susceptibility testing, the MICs for 90% of the MRSA and MSSA isolates tested were 6.25 and 0.39 micrograms/ml, respectively. Two MRSA isolates were resistant to a concentration of greater than 16 micrograms/ml. When 11 MRSA isolates and 7 MSSA isolates were incubated for 48 h the MICs for 90% of the isolates increased to greater than 50 micrograms/ml for the MRSA isolates and 6.25 micrograms/ml for the MSSA isolates. Three S. aureus isolates emerged resistant. Ten of 11 (91%) MRSA infections and 11 of 12 (92%) MSSA infections were clinically cured. Adverse reactions occurred in 25% of the imipenemcilastatin-treated patients. These reactions included gastrointestinal intolerance (7% of the patients), rash or pruritus (6%), eosinophilia (6%), thrombocytosis (4%), and a positive, direct Coomb test without hemolysis (3%). One of the two patients for whom therapy was discontinued because of gastrointestinal intolerance had antibiotic-associated colitis. Imipenem appears to be an effective antistaphylococcal agent against both MRSA and MSSA infections.

Adult↗
PubMedDate not supplied

Suppressive effects on allergic contact dermatitis by short-term fasting.

Fasting alters various hormonal and immune conditions. It has been reported that delayed type immune response to the injection of keyhole limpet hemocyanin was depressed by short-term fasting. In this study, we adopted the computer-assisted image analyzer for histopathological analysis and evaluated the influence of short-term fasting on allergic contact dermatitis induced by 2,4-dinitrofluorobenzene (DNFB). Mice were sensitized by painting of DNFB to the abdomen. After the sensitization, mice were challenged by DNFB painting to the ear. Fasting started 24 hour before (48-hour fasted group) or immediately after (24-hour fasted group) the challenging. Fasting without DNFB treatment did not induce remarkable change of ear thickness, ear tissue, serum albumin, serum total protein, serum glutamic oxaloacetic transaminase, serum glutamic pyruvic transaminase. or serum creatine phosphokinase. In contrast, lasting suppressed the increment of ear thickness in the DNFB-treated group in this study. We could also demonstrate, using the computerized image analyzer, that both lymphocyte infiltration and the edema in the dermis were suppressed in fasted mice treated with DNFB. Further, edema in the dermis was inhibited more strongly in 48-hour fasted mice than in 24-hour lasted mice. These findings indicate that short-term fasting induce histopathological changes in the state of contact dermatitis.

Alanine Transaminase↗
PubMedDate not supplied

In vitro evaluation of combination chemotherapy against human tumor cells (Review).

Combination therapy with multiple drugs or with multiple modalities is common practice in the treatment of cancer. The purpose of using drugs in combinations is to increase the therapeutic efficacy, decrease toxicity toward the host and minimize or delay the development of drug resistance. Presently used clinical protocols for cancer combination therapy are mainly obtained empirically or from clinical trials. Accumulation of experience from clinical trials is invaluable but is a slow and expensive process. Also, due to heterogeneous patient populations exposed to different environments, human clinical data frequently cannot be used for quantitative synergy determinations. Therefore, in vitro quantitative drug combination studies with cultured tumor cells are becoming imperative either as prospective studies or as adjuvant assessment for combination therapy. In recent years, a variety of in vitro assays have been developed to examine cytotoxicity or biochemical effects of drugs on cultured tumor cells. These methods can, not only quickly predict the potential therapeutic effects of the combined agents, but also provide the information or clues to the possible mechanisms of drug interactions. In addition, with the better understanding of various antineoplastic drugs and the development of new technologies to characterize actions of the drugs, the in vitro study of combination therapy is no longer limited to the measurement of cytotoxic effects. Instead, many other studies, such as cell cycle analyses, detection of apoptosis and biochemical analyses of drug interactions have also become common methods for the in vitro evaluation of combination drug therapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

Screening and discovery of novel MDR modifiers from naturally occurring bisbenzylisoquinoline alkaloids.

BACKGROUND: The failure of conventional cancer chemotherapy has been linked to overexpression of a membrane associated P-glycoprotein (P-gp) that acts as an energy-dependent drug efflux pump. A promising strategy to conquer multidrug resistance (MDR) is to develop functional MDR modifiers that can inhibit the activity of P-gp. MATERIALS AND METHODS: We used MTT in combination with other in vitro drug evaluation assays to screen potential MDR modifiers from a series of naturally occurring Bisbenzylisoquinoline Alkaloids (BBIs) that were isolated from natural plants. RESULTS: Our in vitro screening assays indicated that at least six of these natural compounds (FF0019, FF0018, FF0015, FF0014, FF0011 and FF0012) showed potent activities to restore sensitivity of resistant tumor cells, such as MCF-7/adr and KBv200 cells, to many antitumor drugs including doxorubicin and vincristine. Further analyses by measurement of radioactive [3H]-Vincristine indicated that these BBIs increased intracellular drug accumulation in MDR cells, but had little effect on drug-sensitive cells. CONCLUSIONS: These results suggested that the mechanism of these compounds to reverse MDR was associated with the increase in the intracellular drug accumulation through inhibiting the activity of P-gp. Another important feature is that the in vitro cytotoxic effect of these naturally occurring BBIs themselves on tumor cells was very low. Thus, these compounds may possess great promise in being developed into novel MDR modifiers.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

Multiple types of cytokines constitutively produced by an established murine thymic epithelial cell line.

An untransformed murine thymic epithelial cell line (MTEC1) has been established. Without exogenous stimulation, the MTEC1 cells constitutively produced multiple types of cytokines, including IL-1, IL-6, IL-7, GM-CSF and chemotactic factor(s). Of which, IL-6, GM-CSF and chemotactic factor(s) were abundant; IL-1, moderate; and IL-7 at low level. MTEC1 cells neither produced detectable IL-3 nor TNF alpha. Thus, the MTEC1 cells may be useful not only in the evaluation of the signals required for thymic selection in vitro, but also useful in the analysis of the endogenous regulation of the autocrine cytokine production cascade.

Animals↗