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Biomedical subjects

C H Chao

Publications and source records attributed to C H Chao.

16 recordsLinked to original sources
PubMed2001

Phase determination and extension using X-ray multiple diffraction and the maximum-entropy method.

The extension of the phases of the structure factors of the organic crystal C(25)H(25)NO(2) from 77 starting individual phases using the maximum-entropy method is reported. These starting phases were determined from 90 experimental triplet phases calculated from 215 measured psi-scan three-beam and four-beam diffraction profiles obtained with a rotating-anode X-ray source, where the psi scans were around the reciprocal-lattice vectors of the 001, 002 and 003 reflections. The extension of the structure factors with phase values was carried out using the maximum-entropy method for 2040 measured two-beam Bragg diffraction intensities with 77 starting phases and the symmetry of the space group as the constraints. Use of structure-factor triplets as constraints for entropy maximization was also attempted. The minimum chi(2) criteria were applied to the maximum-entropy extrapolation to discern the best phase set to be used as the new constraints for the next step of generating new phases. With this phase-extension procedure, more than 100 phases were determined and an electron-density map at 1.97 A was deduced.

Journal Article↗
PubMed2001

Anomalous dispersion behavior of multiple-wave X-ray diffraction at absorption edges: determination of phase change at resonance.

The effects of anomalous dispersion (resonance) on multiple reflection of x rays and their interference in crystals at atomic absorption edges are studied. Intensity ratios of two inversion-symmetry-related multiple diffractions at or near absorption edges exhibit highly phase-sensitive profiles with strong asymmetric characteristics, unlike those far from the edges. A new resonance perturbation Bethe approach is developed to explain this behavior. This leads to direct determination of the phase change for x-ray reflections at resonance.

Journal Article↗
PubMed2001

Relationship between reproductive performance and immunity in Taiwan country chickens.

Two experiments were conducted to investigate the relationships among reproductive performance, serum gamma-globulin level, carbon clearance ability, and immune responses to phytohemagglutinin and SRBC in the Taiwan Country chicken. In Experiment 1, 480 pullets from 82 sires and 204 dams were used to evaluate the relationship between reproductive performance and immunity. In Experiment 2, 480 pullets, offspring from 55 sires and 173 dams expressing a high or low percentage of serum gamma-globulin and their reciprocal crosses, were used to examine if the level of serum gamma-globulin is associated with reproductive performance and immunity. Results of these experiments indicated that 1) the Taiwan Country chicken had relatively high serum gamma-globulin level compared with those in other reports, 2) serum gamma-globulin level in the Taiwan Country chicken is heritable with an estimate around 0.3 to 0.4, and 3) the high serum gamma-globulin level is genetically associated with low fertility.

Animal Husbandry↗
PubMed2001

Serotonin 6 receptor polymorphism in schizophrenia: frequency, age at onset and cognitive function.

The relative abundance of serotonin 6 receptor (5HT6) in some limbic regions and the high affinity of some antipsychotics for 5HT6 suggest that the 5HT6 gene might play a role in the pathogenesis of schizophrenic disorders. A recent study reported an association between a C267T polymorphism of the 5HT6 gene and schizophrenia. In order to test whether the 5HT6 gene plays a role in the pathogenesis of schizophrenic disorders, patients (n = 148) and control subjects (n = 160) were genotyped for 5HT6. We also investigated the relationship between genotypes and patients' age at onset and cognitive function in schizophrenic patients. Cognitive function in the patients was evaluated by the Mini-Mental State Examination (MMSE). The results demonstrated no significant differences in genotype or allele frequencies between controls and patients. In the patient group, age at onset and MMSE score did not differ significantly among the three 5HT6 genotpyes. The results of this study suggest that the 5HT6 C267T polymorphism plays no major role in susceptibility to the development of schizophrenia and is not related to cognitive impairment or age at onset in schizophrenic patients. Further studies of the relation between 5HT6 polymorphism and the symptoms and the therapeutic response in schizophrenic patients may help to elucidate the role of 5HT6 in the pathogenesis of schizophrenia.

Adult↗
PubMed1999

Identification of victims of the 1998 Taoyuan Airbus crash accident using DNA analysis.

In February 1998 a civilian aeroplane carrying 196 individuals crashed in Taiwan and killed another 6 people on the ground. Although there were dental and medical records, fingerprints, photographic evidence and personal effects to identify some of the victims, DNA analysis was required to further identify severely damaged remains. From the 202 people known to have perished in the plane crash, a total of 685 fragments of human remains were subjected to DNA analysis. The analysis was carried out using nine microsatellite loci, plus amelogenin to cluster the 685 fragments into 202 groups, accounting for all the victims. To establish genetic relatedness of the victims to other victims and living relatives, additional DNA loci were used. In this case the paternity index was increased by using HLA DQA1 plus Polymarker. The same 16 DNA loci were used to test blood samples from 201 relatives to establish parent/child and sibling relationships. With the exception of 19 victims identified by non-genetic evidence, 183 victims were successfully identified by DNA typing with relatively high values of paternity index by the direct or indirect comparison of relatives. The 202 victims were from 37 different families, ranging in size from 2 to 13 members and 74 individuals known to be unrelated to any other victim. The DNA from living relatives was used to identify one member of a family group, from which other victims of the family could be identified. ABO blood group information was further used to confirm genetic relatedness within families. A comparison of the DNA profiling results to the ABO blood group of the victims showed no discrepancies with the exception of two mutations in the FGA locus. In cases of severely damaged victims from a plane crash, DNA analysis proved to be the best choice to identify victims.

Accidents, Aviation↗
PubMed1998

DNA short tandem repeat profiling of Chinese population in Taiwan determined by using an automated sequencer.

We performed a population study on a Taiwan population using a set of nine short tandem repeat (STR) loci and the amelogenin locus. Allele and genotype frequencies of the STR systems D3S1358, vWA, FGA, TH01, TPOX, CSF1PO, D5S818, D13S317 and D7S820 were determined by polymerase chain reaction followed by automated sequencer analysis. A total of 80 alleles could be observed, using all systems, in a population of 500 individuals. No new intermediate fragments were found in these systems. Allele frequencies showed no deviation from the Hardy-Weinberg equilibrium. The mean exclusion power (MEP) ranged from 0.294 for TPOX to 0.711 for FGA (the combined MEP was > 0.999), the discriminating power (DP) ranged from 0.782 for TPOX to 0.964 for FGA, (the combined DP was > 0.99999999949).

Alleles↗
PubMed1995

[Pharmacokinetics and bioavailability of glipizide capsules].

The pharmacokinetics and bioavailability of glipizide were studied in 8 healthy male volunteers after a single oral dose of 5 mg in capsule or in tablet. The plasma levels of glipizide were assayed by high performance liquid chromatography. The concentration--time curves of both preparations were fitted to a one compartment model. The pharmacokinetic parameters of glipizide in capsule and in tablet were shown in tables 2 and 3. The relative bioavailability of the capsule was 109.9% compared with the tablet.

Adult↗
PubMed1992

Mollaret's meningitis: a case report and literature review.

Mollaret's meningitis is a rare syndrome with characteristic features. We present a case with interesting clinical course and cerebrospinal fluid studies. The patient was admitted to Veterans General Hospital-Taipei 6 times between May, 1984 and May, 1991 because of recurrent meningitis (Mollaret's meningitis). No causative etiology was identified although a series of investigations were performed, including studies of the blood and CSF, roentgenogram and nuclear scintinographs. To date, there has been no standard therapeutic modality for this disease. We use aspirin for his symptomatic control with satisfactory result though colchicine has been reported as being effective also.

Humans↗
PubMed1992

Experience of six patients with Vibrio vulnificus septicemia.

Vibrio vulnificus, a halophilic lactose fermenting vibrio, is a virulent pathogen for men and is frequently associated with overwhelming infections of areas other than the gastrointestinal tract. We encountered six cases of Vibrio vulnificus septicemia in Veterans General Hospital-Taipei over the past four years. All were admitted through the emergency room and presented with urgent conditions on arrival. The patients also demonstrated preexisting liver function impairment (either hepatic disease or chronic alcohol consumption). Five subjects had an apparent history of exposure to marine environments: one fisherman with pre-existing wounds and four others with previous consumption of poorly cooked seafood. Characteristic hemorrhagic bullous lesions were found in 5 cases. In all, 4 patients (67%) died with three of the cases within 24 hours of hospitalization. Misdiagnosis and delayed treatment were the most common causes. In conclusion, when patients present with sepsis and/or characteristic cutaneous lesions, particulously those with underlying liver disease and a history of marine exposure, clinicians should be alerted to this potentially fatal infection and should commence appropriate assessment and treatment immediately.

Adult↗
PubMed1991

Tetanus: 20 years of clinical experience.

Tetanus remains a life-threatening disorder and its fulminating course always presents a challenge to the clinician. We retrospectively evaluated 56 patients with tetanus admitted to VGH-Taipei between 1971 and 1990. All of these patients with tetanus on admission showed typical features, with the most common initial complaints being lockjaw and dysphagia (82.6%). They were diagnosed on clinical identification rather than isolation of the causative agent. The laboratory tests were usually nonspecific and of limited value for diagnosis. Overall, 38 patients were seized with tetanus after an identified wound infection. The most common routes were puncture wound (28.3%) and abrasion wound (19.6%). The majority of patients became symptomatic within 10 days (56.5%) and the shorter interval reflected a more overwhelming course (p less than 0.05). Intravenous drug abusers and larger wounds had a poorer prognosis. The average mortality was 39.1% (18 out of 46 patients; male/female 12/6), with lack of statistical difference between sex and mortality (p greater than 0.5). The course of tetanus in the newborn and elderly was also more deadly (mortality rates of 83.3% and 55.6% respectively). Aspiration pneumonia and subsequent respiratory failure accounted for the most common cause (11 cases, 61.1%) of death. The mortality was still high (28.6%) from 1980-90 even with better supportive care and modern therapeutic equipment.

Adolescent↗
PubMed1991

Non-0:1 Vibrio cholerae bacteremia: a case report and literature review.

We reported a case of non-0:1 group Vibrio cholerae septicemia with myelodysplatic syndrome in Taiwan. We also reviewed the other 22 reported cases of non-0:1 Vibrion cholerae septicemia found in the literature regarding its pathogenesis and treatment. The case mortality rate of these 23 cases was 47.8%. Most of them had immunocompromised diseases, particularly liver cirrhosis and hematologic malignancy. Therefore, the most important factor is the host defense. The cholera-like enterotoxin and E1-Tor-like hemolysin also play a major role, but whether the gall bladder plays a role in organ growth is still unclear. The incidence of gastroenteritis is not well understood because of the low incidence of non-0:1 V. cholerae gastroenteritis as compared with other factors such as shell-fish eating. Ampicillin as the sole antibiotic for non-0:1 V. cholerae is not efficacious. Tetracyclines or chloramphenicol is more effective for treatment.

Aged↗
PubMed1991

Overview of viridans streptococcal endocarditis: clinical analysis of 99 cases.

A total of 99 cases of viridans streptococcal endocarditis encountered during the period of 1973 and 1990 at the Veterans General Hospital-Taipei were reviewed to evaluate its prognostic factors. Applying strict clinical and laboratory criteria, 24 cases were categorized as definite, 44 probable, 23 possible and 8 likely. The symptoms were frequently subtle and atypical but initial laboratory tests gave useful indications: 69.1% with leukocytosis, 78% with anemia, 58.5% with elevation of LDH level, 88.9% with elevation of ESR value and 100% with elevation of CRP level. Furthermore, 32.4% of the cases demonstrated proteinuria and 67.4% microscopic hematuria. Seventy-three of the subjects had a history of underlying heart disease, predominantly rheumatic heart disease. Histological examination and echocardiography revealed that 51 patients suffered from vegetative endocarditis, 7 (13.7%) of whom were found to have anatomically confirmed vegetations without initial echocardiographic evidence, Vascular events were seen in 61 cases (61.6%): peripheral stigmata (32 cases), cerebral vascular accidents (17 cases), pulmonary embolism (10 cases) and others (2 cases). The overall mortality rate was 18.2%. Congestive heart failure with embolization was the most common cause of death in this group. The presence of vegetation was not well correlated with embolic events. There was no statistically significant association between the mortality and the following characteristics: age, sex, underlying heart disease, evidence of echocardiographically detected vegetations, major surgical intervention and recurrent cases except for embolic events (p less than 0.01). In conclusion, viridans streptococcal endocarditis complicated embolic events usually presented with a fulminant course and a grave outcome.

Adolescent↗
PubMed1989

[Effect of increasing amounts of clonidine during hyperbaric tetracaine spinal anesthesia].

The effect of adding clonidine to hyperbaric tetracaine spinal anesthesia was investigated in 60 ASA class I-II patients scheduled for orthopedic and lower abdominal surgery. The subjects were randomly allocated into 4 groups. All patients received tetracaine 10 mg in 10% glucose solution 2 mL. Patients in group 1 received above medication and were the control group, patients in the other groups received tetracaine plus increasing dosages of clonidine: 15 microgram (Gr.2), 30 microgram (Gr.3), and 45 microgram (Gr.4). The segmental level of sensory loss was tested by the pinprick method using a 23 G needle. The three clonidine groups had significantly increased in the sensory regression time to L1 level (by 42, 47, 60% respectively), and also had significantly increased motor complete recovery time (by 48, 70, 74% respectively), but the incidence of hypotension and bradycardia was increased in the clonidine 0.045 mg group. It is concluded that addition of 15 or 30 microgram clonidine may be useful as a means of increasing the duration of hyperbaric tetracaine spinal anesthesia.

Adult↗
PubMedDate not supplied

Vaginal lubricants for the infertile couple: effect on sperm activity.

OBJECTIVE: To determine the effects of natural vegetable oils and vaginal lubricants on sperm motion and viability. DESIGN: Four widely used vaginal lubricants (K-Y Jelly, Astroglide, Replens, and Touch) and two vegetable oil products that have been used as vaginal lubricants were purchased through local vendors. Sperm was obtained by masturbation without lubrication from normal, healthy donors. Lubricants were mixed with sperm from individual donors and the effects on sperm motility were determined at 1, 15, 30, and 60 minutes. SETTING: Southwestern Fertility Associates of The University of Texas Southwestern Medical Center at Dallas. MAIN OUTCOME MEASURES: Sperm motility was evaluated by manual motility counts and by computer-assisted semen analysis. Sperm viability was evaluated with Hoechst 33258 dye. The effects of the various lubricants were compared with those of a spermicidal agent, Gynol II (negative control) and Ham's F-10 (positive control). RESULTS: Commercial lubricants inhibited sperm motility by 60-100% after 60 minutes of incubation. Sperm exposed to Replens or Astroglide were nonmotile and nonviable after incubation for 60 minutes, similar to the control, nonoxynol-9 containing product Gynol II. Canola oil had no detrimental effects and was indistinguishable from Ham's F-10 in terms of sperm viability and motility. CONCLUSIONS: For couples with infertility, the use of vaginal lubricants during intercourse is not recommended. In cases where a lubricant is required, careful selection can maximize sperm motility and viability.

Cell Survival↗