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Biomedical subjects

S F Chang

Publications and source records attributed to S F Chang.

At least 55 records · Page 3Linked to original sources

Control of the dehydration process in production of intermediate-moisture meat products: a review.

IM meat products are produced by lowering the aw to 0.90 to 0.60. Such products are stable at ambient temperature and humidity and are produced in nearly every country in the world, especially in developing areas where refrigeration is limited or unavailable. Traditionally IM meats use low cost sources of energy for drying, such as sun drying, addition of salt, or fermentation. Products produced by different processes are of interest since they do not require refrigeration during distribution and storage. Many different IM meat products can be produced by utilizing modern processing equipment and methods. Production can be achieved in a relatively short period of time and their advantages during marketing and distribution can be utilized. Nevertheless, a better understanding of the principles involved in heat transfer and efficiency of production are still needed to increase efficiency of processing. A basic understanding of the influence of water vapor pressure and sorption phenomena on water activity can materially improve the efficiency of drying of IM meats. Predrying treatments, such as fermentation and humidity control, can also be taken advantage of during the dehydration process. Such information can lead to process optimization and reduction of energy costs during production of IM meats. The development of sound science-based methods to assure the production of high-quality and nutritious IM meats is needed. Finally, such products also must be free of pathogenic microorganisms to assure their success in production and marketing.

Absorption↗

Diagnosis of Castleman's disease by identification of an immunophenotypically aberrant population of mantle zone B lymphocytes in paraffin-embedded lymph node biopsies.

Castleman's disease (CD) is characterized by lymph node enlargement due to hyperplasia of abnormal lymphoid follicles and paracortical lymphocytic hyaline vascular (HV) stroma or plasmacytosis (PC). The lymphoid follicles in CD show involuted germinal centers and prominent mantle zone lymphocytes. Ninety-seven cases clinically suspected to be CD were analyzed according to conventional histologic criteria established by Castleman and Keller for diagnosis. Twenty-two cases were excluded as nonspecific hyperplasia (12); Hodgkin's and non-Hodgkin's lymphoma (9); and multiple myeloma involving lymph node paracortex (1). The 75 remaining cases, consisting of 51 cases of CD and 24 with altered follicles or paracortex suggestive of CD, were further analyzed immunohistologically for changes in follicular dendritic reticulum cells (FDRC) using the monoclonal antibody Ki-M4p, for germinal center proliferation with Ki-S5, for mantle zone immunophenotype with Ki-B3 and Ki-B5, for paracortical plasmacytoid monocytes with Ki-M1p, and for plasma cell clonality by applying antibodies to kappa and lambda immunoglobulin light chains. Lymph nodes showing nonspecific follicular and paracortical hyperplasia were included as controls. Hyaline vascular CD and plasma cell CD showed enlarged, polyploid FDRC with prominent nucleoli, decreased germinal center proliferation, and mantle zone populations of immunophenotypically aberrant, Ki-B3-negative B lymphocytes. Thirty-seven percent of hyaline vascular CD and plasma cell CD contained plasmacytoid monocytes, and 15% showed interstitial areas of lambda predominant plasma cells. Plasmacytoid monocytes were common in hyaline vascular CD but rare in plasma cell CD. Cases suspected to be CD that demonstrated a mantle zone population of Ki-B3-negative B lymphocytes had clinical finding of POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal paraprotein, and skin changes or sclerotic bone lesions) syndrome and were reclassified as hyaline vascular CD, plasma cell CD, and mantle zone CD with an aberrant mantle zone immunophenotype only (lacking follicular center and paracortical histologic or immunohistologic abnormalities). Immunohistochemistry was valuable for identification of dysplastic FDRC, decreased germinal center proliferation, and plasmacytoid monocytes. In addition, immunohistochemistry was essential for detection of plasma cell clonality, an aberrant mantle zone immunophenotype, and mantle-zone-restricted CD that was devoid of diagnostic alterations of germinal center or paracortex.

Antibodies, Monoclonal↗

Systemic concentrations of salbutamol and HFA-134a after inhalation of salbutamol sulfate in a chlorofluorocarbon-free system.

The objective of this study was to determine if salbutamol was absorbed from a new salbutamol sulfate chlorofluorocarbon (CFC)-free metered-dose inhaler (MDI). Measurement of HFA-134a, the CFC-free propellant, was included to provide proof of delivery of this MDI. Eight healthy men received two inhalations (90 micrograms salbutamol base equivalents per inhalation ex adapter) from the CFC-free inhaler (MDI A) in period 1 and from a reference CFC inhaler (MDI V) in period 2. Eight postdose samples were collected for the determination of salbutamol serum levels over a 4-h period. Salbutamol levels were not quantifiable in most samples. Four subjects given MDI A and two given MDI V had a few transient salbutamol levels, which occurred in the first hour after dosing, within a narrow range of 1-2 ng/ml and close to the lower limit of detection (1 ng/ml). No pharmacokinetic analyses were possible. Blood samples were also collected after MDI A for propellant quantitation. HFA-134a levels were seen in all subjects, verifying absorption. We conclude that the transient salbutamol serum levels can be attributed to the two-inhalation dose and not to either propellant system.

Administration, Inhalation↗

Determination of the chlorofluorocarbon substitute 1,1,1,2-tetrafluoroethane (HFA-134a) in human and animal blood using gas chromatography with headspace analysis.

A gas chromatographic procedure with headspace analysis and flame-ionization detection is described for the determination of the chlorofluorocarbon substitute 1,1,1,2-tetrafluoroethane (HFA-134a). A 0.5-2 ml sample of heparinized whole blood from a laboratory animal or human is added directly into a presealed headspace vial from which an equivalent volume of air has been removed. The internal standard 1,1,2,2-tetrafluoroethane is added and the sample frozen until analysis. Chromatographic separation is achieved using a PoraPlot Q porous-layer capillary column. The analytical range is 5.8-3298 ng/ml when 2-ml human blood samples are used. The concentration range of the calibration curve can be easily adapted to accommodate the concentrations expected in either pharmacokinetic or toxicokinetic studies. Automation of the assay permits the maximum number of samples to be processed in a day.

Adult↗

Cytomegalovirus infection and viral shedding in the genital tract of infertile couples.

The prevalence of cytomegalovirus (CMV) infection and viral shedding in infertile couples in Taiwan and its role in infertility were studied. Two hundred fifty couples were enrolled in this study. Anti-CMV IgG was measured in serum samples from these infertile couples. Viral shedding examined by DNA hybridization was detected in semen from the husband and cervical mucus from the wife. Anti-CMV IgG was detected in 249 (99.6%) of the 250 male serum samples and in 247 (98.9%) of the 250 female serum samples. Viral shedding was detectable in 83 (33.5%) of 248 semen samples and 83 (33.7%) of 246 cervical mucus samples by dot-blot DNA hybridization assay. Semen quality was not apparently affected by the existence of viral shedding. The co-shedding rate in semen and cervical mucus was high (15.9%). It is concluded that the seroprevalence and genital tract viral shedding were relatively high in infertile couples in Taiwan. Viral shedding did not affect the semen quality. Nevertheless, screening of donor semen is recommended.

Adolescent↗

Evolution of the feline-subgroup parvoviruses and the control of canine host range in vivo.

A related group of parvoviruses infects members of many different carnivore families. Some of those viruses differ in host range or antigenic properties, but the true relationships are poorly understood. We examined 24 VP1/VP2 and 8 NS1 gene sequences from various parvovirus isolates to determine the phylogenetic relationships between viruses isolated from cats, dogs, Asiatic raccoon dogs, mink, raccoons, and foxes. There were about 1.3% pairwise sequence differences between the VP1/VP2 genes of viruses collected up to four decades apart. Viruses from cats, mink, foxes, and raccoons were not distinguished from each other phylogenetically, but the canine or Asiatic raccoon dog isolates formed a distinct clade. Characteristic antigenic, tissue culture host range, and other properties of the canine isolates have previously been shown to be determined by differences in the VP1/VP2 gene, and we show here that there are at least 10 nucleotide sequence differences which distinguish all canine isolates from any other virus. The VP1/VP2 gene sequences grouped roughly according to the time of virus isolation, and there were similar rates of sequence divergence among the canine isolates and those from the other species. A smaller number of differences were present in the NS1 gene sequences, but a similar phylogeny was revealed. Inoculation of mutants of a feline virus isolate into dogs showed that three or four CPV-specific differences in the VP1/VP2 gene controlled the in vivo canine host range.

Amino Acid Sequence↗

Weather and stroke in a subtropical area: Ilan, Taiwan.

BACKGROUND AND PURPOSE: The aim of this study was to clarify the association of weather and stroke occurrence in a subtropical area in Ilan, Taiwan. METHODS: We studied 517 patients with stroke (date of onset, January 1 to December 31, 1991) in Poh-Ai Hospital and St Mary's Hospital: 316 patients (61.1%) with cerebral infarction, 170 (32.9%) with intracerebral hemorrhage, and 31 (6.0%) with other types of stroke. The daily occurrence of cerebral infarction and intracerebral hemorrhage was analyzed and correlated with three major meteorologic factors: air temperature, air pressure, and relative humidity. RESULTS: The occurrence of cerebral infarction was rather uniform in all kinds of weather. The occurrence of intracerebral hemorrhage was approximately twice as great on cold days (0.71 case per day) and high-pressure days (0.73) as on warm days (0.31) and low-pressure days (0.39) (P < .005 by chi 2 test). When a linear regression model was used to test whether air temperature or air pressure had more influence on intracerebral hemorrhage, only air temperature showed a significant effect. Regarding intracerebral hemorrhage, the relative risks of cooler and median temperature days versus warmer days were 18.5 and 5.1, respectively. CONCLUSIONS: Intracerebral hemorrhage but not cerebral infarction occurs more frequently on cooler days, with a dose-response relationship, in Ilan, Taiwan.

Aged↗

Difference in transcriptional activity of two homologous CYP21A genes.

Steroid 21-hydroxylase (CYP21) deficiency is the major cause of congenital adrenal hyperplasia, a common genetic disease due to steroid imbalance. The main cause for the mutation of the CYP21A2 (c21B) gene is conversion of its nucleotide sequence to the neighboring homologous but nonfunctional c21A gene. In this report the transcriptional activities of the c21A and c21B genes have been analyzed. Transient transfection assays showed that transcription derived from the c21A gene was about 5-fold lower in strength than that of the c21B gene, although both sequences responded to cAMP normally in two adrenocortical cell lines. The normal response to cAMP could probably be attributed to equal activation of both genes by a transcription factor Nur77. The lower transcriptional activity of the c21A gene was attributed to sequence changes within 167 base pairs of the 5'-flanking region, which differs from the c21B gene by only four nucleotides at positions around -100. These four nucleotide changes render the c21A sequence to bind proteins less tightly than the -100 region of the c21B sequence, which binds proteins such as transcription factor Sp1 in electrophoretic mobility shift assays. The reduced transcription due to nucleotide changes at the regulatory region of the c21A gene, in combination with other mutations in the coding region, could play important roles in 21-hydroxylase deficiency.

Base Sequence↗

Comparison of the genetic variation in type 1 dengue virus isolates in Taiwan, 1987-1992.

In this study, the genetic variation of eight dengue-1 strains isolated in Taiwan from 1987 to 1992 (including two imported strains) were studied. A fragment of 490 nucleotides from the E/NS1 junction was amplified and studied by reverse transcription-polymerase chain reaction (RT-PCR) and vector cloning. By comparing the nucleotide sequences of these strains, it was found that local strains in Taiwan shared geographic similarity. The nucleotide differences among local strains were less (0.61% to 2.24%) than the differences between imported strains and other strains (2.04% to 4.29%). The differences of nucleotide sequences between local strains and the prototype remain constant (5.10%-5.29%). However, the differences in nucleotide sequences between imported strains and the prototype ranged from 3.89% to 7.14%. Since the point mutations occurred in the wobble position of the codon, only conserved changes resulted in the amino acid among the isolates.

Amino Acids↗

Cervical cytomegalovirus infection in prostitutes and in women attending a sexually transmitted disease clinic.

This study aimed to determine the frequency of, and to define factors associated with, cervical shedding of cytomegalovirus (CMV) in highly sexually active women (licensed prostitutes) and in women attending a sexually transmitted disease (STD) clinic. Cervical specimens obtained from 195 licensed prostitutes and 187 STD patients aged 17-50 years were compared for the presence of cervical CMV with specimens from 70 women of the same ages attending a gynecologic clinic. Cervical CMV was identified by the presence of a CMV-specific immediate-early gene sequence amplified by the polymerase chain reaction. Cervical CMV prevalences of 38.9% and 34.8% were found for licensed prostitutes and STD patients, respectively. These rates were significantly higher than the 24.3% cervical CMV prevalence for women attending the gynecologic clinic. The data suggest that frequent sexual contact with many sexual partners is responsible for the high frequency of cervical CMV observed in licensed prostitutes. The interaction between CMV and urogenital bacterial infections is a plausible explanation for the high cervical CMV prevalence in STD patients.

Adolescent↗

Humoral immune responses and cytomegalovirus excretion in children with asymptomatic infection.

Forty-two seropositive children aged 3 to 5 years attending a kindergarten were followed up for 1 year in order to examine the relationship between humoral immunity and cytomegalovirus (CMV) excretion status. Anti-CMV antibodies were measured at the beginning and end of the study by enzyme-linked immunosorbent assay, neutralizing antibody test, and immunoblot techniques. Among these children, 32 persistently shed virus in urine, 2 intermittently shed CMV, and 4 experienced reactivation during the study. Virus was never isolated from 4 seropositive children. The level of anti-CMV IgG antibody in seropositive children who remained nonshedders was significantly higher than in children who shed virus during follow-up. On immunoblots, all seropositive nonshedders reacted to a CMV-specific 65 kD antigen, whereas most shedders (80%) did not. These findings suggest that humoral immunity plays a role in controlling persistent CMV infection in children with asymptomatic infection. However, the humoral immunity measured by the neutralizing test and the presence of antibodies against CMV-specific envelope antigens (116 kD/55 kD) apparently play a limited role in modifying persistent excretion and regulating reactivation of latent CMV. Immune evasion by CMV to block these antigens may explain these results.

Antibodies, Viral↗

Comparative pharmacokinetics of morning and evening doses of once-a-day theophylline capsules.

The objective of this study was to determine if the theophylline diurnal variation that has been observed primarily between morning and evening doses of twice-a-day products could be overcome by a once-a-day formulation. Eighteen healthy, nonsmoking, adult male subjects were given 900-mg theophylline doses as three 300-mg once-a-day theophylline capsules in the morning or evening for 5 days in a single-blind fashion. Matching placebo capsules were administered midway between each dose of active drug. Predose theophylline serum levels on day 3-6 were statistically equivalent within each treatment, indicating that approximate steady-state conditions were achieved by day 3. Mean serum level profiles over the 24-h interval following the active dose on day 5 were almost superimposable for the morning and evening treatments. All pharmacokinetic parameters were equivalent between the treatments, except for the time to peak serum level (Tmax), which was significantly shorter for the morning dose. Given the flatness of the serum level curves for both treatments, the Tmax difference was judged to be clinically unimportant. A small peak-trough level fluctuation of about 50% was seen with each treatment. We conclude that by designing a dose form in which drug release was the rate-limiting step in drug absorption, the diurnal variation commonly associated with theophylline formulations may be eliminated.

Adolescent↗

The altered expression of cytokeratin polypeptides in carcinomas of human bladder.

After extraction in high salt buffers and Triton X-100, cytokeratin polypeptides could be isolated from normal epithelium and transitional cell carcinoma of the human bladder in the southwestern coast of Taiwan. The polypeptides were solubilized via lysis buffer, separated by two-dimensional gel electrophoresis, and identified by immunoblot. Five cases of normal epithelium expressed cytokeratin No. 5 (58 kd), 7 (54 kd), 18 (45 kd) and one case further expressed cytokeratin No. 19 (40 kd) in addition to the above cytokeratins. Combined patterns of cytokeratin polypeptides were observed among various Grades of transitional cell carcinoma of bladder. Comparing the patterns between the normal epithelium and the transitional cell carcinoma of bladder, 88% (14/16) of carcinomas expressed cytokeratin No. 8 (52.5 kd) and 63% (10/16) expressed No. 17 (46 kd), which were not seen in the normal epithelium. Some other cytokeratin polypeptides particular to carcinomas were No. 4 (59 kd), No. 10 (56.5 kd), No. 13 (54 kd) and No. 14 (50 kd) and were only present in less than 50% (ranging from 31-56%) of the examined specimens. Thus cytokeratin No. 8 and 17 could be helpful markers for diagnosis of bladder carcinoma.

Carcinoma, Transitional Cell↗

[Drug resistance and plasmid analysis in Pseudomonas aeruginosa].

One hundred and ninety seven strains of Pseudomonas aeruginosa were isolated from urine (59 strains), wound pus (60 strains), sputum (30 strains), stool (30 strains) and eye discharge (18 strains) at Kaohsiung medical College Hospital. These strains were serotyped with antisera against O antigens and tested with twelve different antimicrobial agents. The results showed that the most frequently isolated strains were serotype E (41.1%), followed by serotype B (20.3%), serotype F (10.7%) and serotype L (9.1%). In in vitro susceptibility testing, all isolated strains were resistant to chloramphenicol and tetracycline. Otherwise, these isolates were highly susceptible to ceftazidime (95.4%), enoxacin (89.3%) and piperacillin (87.8%). The isolates from urine exhibited more multiple drug resistance patterns than those of other specimens. When plasmid content was analysed from pseudomonas aeruginosa, only 15.2% (30/197) of isolates carried plasmids. By conjugation, transformation and mobilization experiments, it was shown that 13.3% (4/30) of plasmid carrying strains contained R plasmids.

Chloramphenicol↗