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Biomedical subjects

H C Chen

Publications and source records attributed to H C Chen.

At least 307 records · Page 17Linked to original sources
PubMed1994

Oxygen reactivity in diabetes mellitus: effect of hypertension and hyperglycaemia.

1. Laser Doppler velocimetry and computerized image analysis of retinal photographs were used to define retinal vascular autoregulation to 60% oxygen breathing. This normally causes vasoconstriction in the retinal circulation. Normotensive and hypertensive diabetic subjects were studied under conditions of relative normoglycaemia (< 10 mmol) and hyperglycaemia (> 15 mmol) together with control subjects. 2. Retinal blood flow was significantly higher in diabetic subjects when hypertensive and hyperglycaemic than in the same diabetic subjects when normotensive. 3. In the normotensive non-diabetic subjects the oxygen reactivity was 41.16 +/- 14.09%. It was significantly reduced in normotensive 'hyperglycaemic' diabetic subjects (21.75 +/- 15.56%), hypertensive diabetic subjects with controlled blood pressure and 'normoglycaemia' (30.49 +/- 14.20%), hypertensive diabetic subjects with controlled blood pressure and 'hyperglycaemia' (18.36 +/- 11.42%), hypertensive diabetic subjects with uncontrolled blood pressure and 'normoglycaemia' (26.91 +/- 13.43%) and hypertensive diabetic subjects with uncontrolled blood pressure and 'hyperglycaemia' (17.17 +/- 13.24%) (mean +/- SD, all P values < 0.05). 4. In conclusion, retinal vascular reactivity is impaired in diabetic subjects both when they are normotensive and when they are hypertensive. Hyperglycaemia, to a degree commonly encountered in clinical practice, impairs retinal vascular auto-regulation even further.

Adult↗
PubMed1994

Direct interaction of v-Src with the focal adhesion kinase mediated by the Src SH2 domain.

The recently described focal adhesion kinase (FAK) has been implicated in signal transduction pathways initiated by cell adhesion receptor integrins and by neuropeptide growth factors. To examine the mechanisms by which FAK relays signals from the membrane to the cell interior, we carried out a series of experiments to detect potential FAK interactions with proteins containing Src homology 2 (SH2) domains that are important intracellular signaling molecules. Using v-Src-transformed NIH3T3 cells, we showed that FAK was present in the immune-complex precipitated by anti-Src antibody, suggesting potential interaction of FAK with v-Src in vivo. We also showed potentially direct interaction of FAK with v-Src in vivo using the yeast two-hybrid system. Using recombinant FAK expressed in insect cells and bacterial fusion proteins containing Src SH2 domains, we showed direct binding of FAK to the Src SH2 domain but not to the SH3 domain in vitro. A kinase-defective mutant of FAK, which is not autophosphorylated, did not interact with the Src SH2 domain under the same conditions, suggesting the involvement of the FAK autophosphorylation sites. Treatment of FAK with a protein-tyrosine phosphatase decreased its binding to the Src SH2 domain, whereas autophosphorylation in vitro increased its binding. These results confirm the importance of FAK autophosphorylation sites in its interaction with SH2 domain-containing proteins. Taken together, these results suggest that FAK may mediate signal transduction events initiated on the cell surface by kinase activation and autophosphorylation that result in its binding to other key intracellular signaling molecules.

3T3 Cells↗
PubMed1994

Effects of age and available response time on ability to step over an obstacle.

BACKGROUND: Falls during walking are often triggered when a foot contacts an obstacle in its path. Yet little is known about the ability of individuals of any age to successfully negotiate obstacles, especially under time-critical conditions. METHODS: The gait of 24 young and 24 old healthy adults (mean ages 23 and 73 years) was studied as they approached and tried to avoid stepping on a band of light, not knowing when or where it might appear on an 8 m-long walkway. This virtual obstacle was placed at the predicted location of the next footfall with available response times (ART) before heel strike that were varied randomly in 50 ms increments from 200 to 450 ms. In addition, their gait was observed as they stepped over a fixed virtual obstacle and over an obstacle that appeared with approximately a 1000 ms ART. RESULTS: The old had an increased risk of obstacle contact while negotiating obstacles under time-critical conditions (p = .082). Mean rates-of-success (RS) in obstacle avoidance for the young ranged from .205 at a 200 ms ART to .969 at a .450 ms ART. Corresponding mean RS for the old were .157 and .920. Lower extremity simple reaction time (SRT) test made under static conditions showed that the mean SRT of the old were approximately 80 ms longer than those of the young. Regression analyses suggested that the old in fact would have needed only 30 ms additional ART to achieve RS equal to that of the young for obstacles appearing with ART from 300 to 450 ms. CONCLUSIONS: Reductions in ART significantly decreased RS. Delays as small as 50 or 100 ms in observing or reacting to obstacles in real-life situations may significantly lower the rate of success that subjects of any age have in avoiding them. Age differences in SRT do not always reliably indicate age differences in obstacle avoidance under time-critical situations.

Accidental Falls↗
PubMed1994

Beta A3/A1-crystallin association: role of the N-terminal arm.

The beta- and gamma-crystallins of the lens form a protein superfamily, the beta gamma-crystallins and have highly conserved two-domain core structures. Whereas gamma-crystallins exist as monomers, the beta-crystallins associate into large aggregates. The N-terminal extensions to the core domains of beta-crystallins are postulated to be essential for their aggregation characteristics. To test this hypothesis, we compared the aggregation properties of a recombinant mouse beta A3/A1-crystallin without its N-terminal extension (r beta A3tr) to a normal recombinant mouse beta A3/A1-crystallin (r beta A3). The identity of the baculo-virus system-expressed recombinant crystallins was confirmed by gel electrophoresis, immunoblots and N-terminal sequence analysis. Circular dichroism measurements indicate that the recombinant crystallins have mostly beta-sheet conformation, similar to normal beta-crystallins. The normal r beta A3 migrates on gel filtration chromatography as a homodimer, whereas the r beta A3tr migrates mostly as a monomer. After relocating the recombinant crystallins with mouse lens soluble extract, r beta A3 migrated with the dimeric beta L2 fractions and to a lesser extent with tetrameric beta L1 fractions. The reassociated r beta A3tr migrated with the trailing edge of the beta L 2 fractions (40 kDa). These results suggest that the N-terminal arm of beta A3/A1-crystallin facilitates dimer formation and is necessary for higher-order associations.

Amino Acid Sequence↗
PubMed1994

Miniature plates and screws in acute complex hand injury.

Thirty-six patients with 72 metacarpal and phalangeal fractures with associated injuries to the neurovascular bundle, tendon, soft tissue, or bone following acute complex hand injury were treated with miniature plates and screws and reconstruction of the disrupted and missing structures. The results were judged according to the criteria of the American Society for Surgery of the Hand. The overall results were good in 46.3%, fair in 32.2%, and poor in 21.5%. Although traditional wiring techniques are certainly useful in complex hand injuries, internal osteosynthesis with miniature plates and screws has definite indications in cases requiring stable and rigid internal fixation.

Adult↗
PubMed1994

Microsurgical thumb reconstruction with toe transfer: selection of various techniques.

Microsurgical toe transfer is an established method for reconstruction of missing thumbs. However, there is little agreement on which of the various techniques represents the ideal transfer. Basically, selection of technique requires balancing the patient's functional needs, appearance of the reconstructed thumb, and donor-site cosmesis. Based on our experience with 103 toe-to-thumb transfers performed over the past 9 years, this paper attempts to provide guidelines for appropriate selection among the four most commonly employed toe transfer techniques (e.g., second toe, total great toe, great toe wrap-around, trimmed great toe) so that optimal results and patient's acceptance can both be achieved.

Adolescent↗
PubMed1994

Transposed replantation of fingers at forearm bones in severe segmental injuries across the hand and wrist.

There are situations in which amputated hands or fingers cannot be replanted directly back to their original positions. When there is severe segmental injury across the hand and wrist but one or several fingers are still healthy, the fingers can be selected to be replanted at the forearm bones to restore pinch function. This is different from the toe to antebrachial stump transplantation presented by Dr. Vilkki. From the results in four patients, the following conclusions are drawn: (1) When the fingers are replanted at the forearm bone(s), only pinch function can be obtained. There is no opposition. (2) Grip function is weak because the intrinsics are lost and only a few fingers are replanted. The forearm bones are often shortened, as are the flexors. (3) Of particular importance is the creation of a large web space between the radial digit and ulnar digit(s), because fingers are longer than toes. (4) The sensory recovery is not so good as in ordinary finger replantation. However, this is a salvage procedure. Regardless of these facts, the patients are still satisfied with the results out of such severe injuries. With good pinch function, not only are they independent in daily life, but they also can do a lot of work. It is a worthwhile procedure. A functional prosthesis can be added distally after this replantation.

Adult↗
PubMed1994

Detection of penicillin G in milk using a conductimetric method.

A highly sensitive method was developed that used conductance measurement for the detection of penicillin G in milk. The method is based on the inhibition by the antibiotic on the growth of Bacillus stearothermophilus ATCC 10149. The conductance change in PM indicator agar containing the bacterial spores was continuously monitored at 55 degrees C by a microbiological analyzer, and the detection time was delayed when penicillin G was present in the samples. The detection limit of the method for penicillin G was .00016 IU/ml with a detection time of about 3.4 h, but only a narrow range (.00016 to .00062 IU/ml) of the antibiotic could be quantitatively analyzed. The conductimetric method is about 30 times more sensitive than several methods currently used. In addition, the conductance measurement is fully automatic, and multiple samples, 120 or 240, can be analyzed simultaneously.

Animals↗
PubMed1994

[Analysis of risk factors of postpartum hemorrhage in rural women].

Sixty variables during pregnancy, labor and delivery of 951 rural women were analyzed to identify the risk factors of postpartum hemorrhage. The result showed that uterine atony (RR = 13.30, 95% CI = 8.23-21.50) and its related factors were the major risk factors of postpartum hemorrhage. The related factors included prolonged labor (3.49, 1.98-6.15), prolonged second stage of labor (2.72, 1.54-4.78), pregnancy induced hypertension (mild 2.35, 1.11-4.99; > or = moderate 3.04, 1.38-6.70), neonatal weight > or = 3.500 g (2.55, 1.66-3.91). Another category of postpartum hemorrhage risk factors were placental factors (6.32, 2.35-17.01), the third stage of labor > or = 10 minutes (2.65, 1.74-4.01), parity > or = 2 (2.61, 1.69-4.01) and maternal age > or = 30 (2.19, 1.13-4.24). The authors recommends that the stress should be put on the management of labor and delivery, to prevent and management of postpartum hemorrhage, through training the birth attendants to promote their ability to prevent and manage uterine atony and correct management of labor and delivery.

Adult↗
PubMed1994

Dinucleotide repeat polymorphisms at nine loci in sporadic colorectal cancer.

Genomic instability in the form of microsatellite alterations at nine loci on chromosomes 2p, 8p, 10p, 11p, and nm23-H1 locus on 17q21.3 were studied in sporadic colorectal tumors. Alterations in dinucleotide repeats in tumor DNA as larger allele, smaller allele, or loss of heterozygosity (LOH) were observed. Forty percent of tumor showed an RER+ phenotype. A significantly high number of alterations was detected at loci of chromosome 8p. The markers on chromosomes 2p, 10p, and 11p did not show such significant alteration. LOH was found to be associated with the nm23-H1 locus. No correlation was found between the age, site of tumor occurrence, or metastasis and the microsatellite instability.

Adenocarcinoma↗
PubMed1994

Abdominal wall hernia complicating continuous ambulatory peritoneal dialysis.

Continuous ambulatory peritoneal dialysis (CAPD) is a well-established treatment modality for end-stage renal disease. Abdominal wall hernia is not uncommon in patients on CAPD. Two factors are responsible for the occurrence of these hernias: anatomically weak sites and increased intraperitoneal pressure by the dialysate. Abdominal wall hernia was reviewed in 44 patients on CAPD from 1987 through 1991. Eight abdominal hernias (5 inguinal, 2 incisional and 1 umbilical) were found during CAPD treatment (18.18%). Surgical treatment was applied in 6 symptomatic hernias (5 inguinal and 1 incisional). After surgery, 5 patients returned to CAPD without recurrence and the remaining one died of strangulated incisional hernia. Our series shows that: (1) a detailed examination of the preexisting hernia and repair prior to CAPD treatment are suggested. (2) symptomatic abdominal wall hernia should be evaluated carefully and treated promptly. (3) awareness of the complication of these hernias can reduce the morbidity and mortality.

Adult↗
PubMed1994

[The utilization of health care by the elderly with chronic health problems in Kaohsiung City].

The purpose of this study was (1) to ascertain whether or not the elderly utilized the health care system and did follow-up after the initial free health check-up and screening; (2) to investigate the types of chronic health problems the elderly who utilize health care had and their reasons for using the health care system; and (3) to explore related factors that influence the utilization of health care by the elderly. In this study, 484 elderly individuals were interviewed by home visits. All names were from the 11 public health clinics in Kaohsiung City, and all subjects had been diagnosed with one of the following disorders: heart disease, diabetes mellitus, hypertension, liver and biliary disorder, urinary disorder, or lung disease. Data were statistically analyzed by means of descriptive and analytical methods, %, t-test, Chi-Square test and odds ratio. The major findings of this study were as follows: (1) the utilization rate by chronically ill elderly was 80.2%. (2) elderly with multiple utilization of the health care system comprised 33.8%. (3) the variables influencing the utilization of the health care system included: perceived susceptibility, fixed physician, medical insurance, doctor's attitude, social support, community health nurse follow-up, the number of diseases, perceived severity of the illness, and attitude of health.

Aged↗
PubMed1994

Persistent light reaction with erythroderma caused by musk ambrette: a case report.

Persistent light reaction is an uncommon type of photodermatitis caused mainly by musk ambrette, a synthetic fragrance material commonly used in foods and cosmetics. Erythrodermic persistent light reaction is rare. We report a case of erythroderma with underlying persistent light reaction due to musk ambrette. A 71-year-old man showed a photodermatitis that waxed and waned for five years before it became more persistent and finally evolved into erythroderma. Positive results of a photopatch test to musk ambrette and a low minimal erythema dose to ultraviolet B were noted. A biopsy specimen of the erythrodermic lesion revealed spongiotic dermatitis. The erythroderma and photodermatitis responded to systemic steroids and psoralen/ultraviolet A therapy (total dose: 90 J/cm2). We suggest that persistent light reaction be included in the differential diagnosis of erythroderma.

Aged↗
PubMed1994

[Proximal interphalangeal joint dorsal dislocations without fractures--four cases report].

Four patients with proximal interphalangeal joint (PIP) dorsal dislocation without fracture had been treated at Chang Gung Memorial Branch (Kaohsiung and Keelung) Hospital from June 1987 to Jan. 1989. All four cases were open dislocations, only one patient received immediate diagnosis and treatment, while the other 3 cases were delayed diagnosis and treatment. Open reduction, repair of the ruptured ligaments and joint capsule, reinsertion of the disrupted volar plate were given in these 4 patients. The patient with immediate surgical treatment received rehabilitation program, the other three patients with delay surgical management did not receive rehabilitation program. The rehabilitation program included early active exercises of the PIP joint, started from the second week postoperatively. The rehabilitation period was about three to six months. The prompt diagnosis, reduction, institution of appropriate treatment and rehabilitation might result in better function of the PIP joint after dorsal dislocation.

Adolescent↗
PubMed1994

Intestinal lengthening experience in short-bowel swine.

BACKGROUND: Traditional therapy for short-bowel syndrome is long-term, expensive and inconvenient; it is often associated with high morbidity and mortality. Thus, there has been increasing interest in the surgical management of this syndrome. Intestinal lengthening is attractive not only because of tapering of the dilated intestine, but also for preserving the intestine that is tapered. The purposes of this study were (a) to develop a reproducible surgical technique for intestinal lengthening and (b) to assess the response of the lengthened jejunum to a short-gut situation. METHODS: Fourteen pigs weighing 13-20 kg were chosen for the study. The animals were divided into three groups: Group I: two pigs received a 20 cm jejunum lengthening only; Group II: six pigs received an 80% bowel resection only; Group III: six pigs received an 80% bowel resection, followed by a 20 cm loop lengthening in the residual jejunum four to seven weeks later. All were observed for a period from 4 to 28 weeks. RESULTS: All lengthened loops, of either primary lengthening (Group I) or delayed lengthening (Group III) functioned well and showed no clinical leakage. Three pigs in Group II (bowel resection only) died of malnutrition at the 5th, 10th and 19th postoperative week, respectively. Only one pig in Group III died, 67 days after bowel lengthening, from intestinal obstruction. During sacrificing laparatomy, two pigs in Group III were found to have side to side enteroenteral fistulae between the lengthened loops. The lengthened bowel was found to be normal histologically. CONCLUSIONS: These results proved that intestinal lengthening is technically feasible, and may be useful for patients suffering from surgical short-bowel syndrome and who have not been completely weaned off parenteral feeding.

Animals↗
PubMed1994

The use of field effects to generate calcium alginate microspheres and its application in cell transplantation.

The diameter and sphericity of alginate-poly-L-lysine-alginate microcapsules, which was determined by the size and shape of calcium alginate microspheres, affected durability and biocompatibility of microcapsules and the result of transplantation. The commonly used airjet spray method generated microspheres with wide variation in diameter and sphericity. In order to overcome these drawbacks, we designed a field effect microparticle generator which established a stable electric field. This generated calcium alginate microspheres with an adjustable diameter (range, 50-350 microns). Factors which influenced the diameter and sphericity of microspheres included the percentage of alginate, field strength, speed of extrusion of alginate, needle gauge, field distance, and cell density in sodium alginate. The conditions used for microencapsulation of rat, pig, and human islets were 5500-6500 volts, 22 gauge needle with blunt end, 1-cm field distance, 1.5% sodium alginate, and 0.57 mL/min extrusion speed. These combinations would give most of the islet-containing microcapsules a diameter of 300-450 microns when alginate microspheres were incubated with calcium chloride solution for a total of six minutes. If individual cells (eg, NS-1) were microencapsulated, a larger gauge needle resulted in smaller microcapsules. Field strength of 6500 volts at a distance of 1 cm did not change the doubling time of NS-1 myeloma cells. By using the electric field microparticle generator, encapsulated cells were distributed around the periphery of the microspheres and thus improved the oxygen and nutrient supply of these encapsulated cells.

Alginates↗
PubMed1994

[Family influence on cancer screening participation in seven communities in Taiwan].

Cancer is the leading cause of death in Taiwan. Since there is no definitive method for cancer prevention, early detection play a major role in fighting cancer. Factors that affect people's willingness to participate cancer screening have been discussed widely except for those relating to the family. The family's role in motivation & influencing its members to participate in an invited cancer-screening program was studied in seven Taiwanese communities. 5% of participants in each area for both genders were chosen by stratified random sampling, and matched with teice-informed nonparticipants who were chosen by sex, age, and neighborhood. By means of a home visit and structured questionnaire, 729 of the 987 eligible cases were interviewed (73.9%). The main findings were that the response was higher among people with higher education, nonsmokers, and those who felt the scheduled time and place of attendance was suitable and convenient. Moreover, in the 6 variables related to family (family structure, family life cycle, cancer history in family and friends, family APGAR, family support about health problems, and family's opinion about cancer screening), the last 4 variables were found to be significantly related by chi-square analysis to the attendance. Finally, a logistic regression analysis adjusted by age, sex, education, smoking habits, time available and traffic factors was used to analyze how family factors affect attendance. The result was cancer history in family and friends (odd ratio = 2.42) and family's encouragement (odd ratio = 1.85) had a positive association.

Adult↗