Search PubMed⌕ Search

Biomedical subjects

K C Chang

Publications and source records attributed to K C Chang.

At least 163 records · Page 9Linked to original sources
PubMed1990

The influenza resistance murine Mx1 gene is constitutively expressed in the epithelia of the gastrointestinal, respiratory and uterine tracts.

The murine Mx1 gene confers specific resistance against influenza in the inbred A2G mice and in vitro have been shown to be inducible with type I but not type II interferons. Contrary to expectation, we found by in situ hybridisation widespread Mx1 expression along the epithelia of the gastrointestinal, uterine and respiratory tracts in uninduced A2G mice. Several lines of evidence, including further enhancement of Mx1 expression during organ culture and gnotobiotic mice analyses, indicated that this apparent constitutive epithelial Mx1 expression was a locally induced response to stimuli present in the respective lumina. This phenomenon may be a feature found in other interferon-inducible and interferon genes.

Animals↗
PubMed1990

Neurinoma of the spinal accessory nerve: report of a case.

We report a patient with neurinoma of the spinal accessory nerve, who complained of intermittent occipital headaches, nausea, vomiting, blurred vision and unsteady gait. Neurological examination revealed papilledema, bilateral horizontal nystagmus and right cerebellar signs. Computed tomography revealed mild hydrocephalus, a low-attenuated lesion with a faint capsule after enhancement and partial compression of the 4th ventricle in the right posterior fossa. Vertebral angiography revealed no definite tumor vessels or stains. Under the impression of a posterior fossa tumor, a suboccipital craniectomy with a C1 and C2 laminectomy was performed. A 4 x 4 x 2.5 cm3 dumbbell tumor arising from the left spinal accessory nerve at the C2 level was found 4 x 4 x 2.5 cm3. The tumor extended upward through the foramen magnum with upward displacement of both tonsils to the right jugular foramen with slight adhesion to the right IX, X and XI cranial nerves. The left spinal accessory nerve was severed from the pedicle at the C2 level, and the tumor was totally removed. Diagnosis was made during the operation. The pathological examination showed neurinoma with cystic degeneration. During the following year, atrophy of the left sternocleidomastoid and trapezius muscles were noticed. Up to the time of this writing, there had been no clinical recurrence.

Accessory Nerve↗
PubMed1990

[Fleur-de-lis flap].

An Abbe flap with lateral vermilion extension (Fleur-de-lis flap) was used in four cases of secondary deformity of lip and palate with tightness and thinness of upper lip following primary cleft lip and palate surgery. The Abbe island flap was converted into fleur-de-lis flap with extensive mucosal wings to improve the fullness of the upper lip. The results were considered to be superior to those obtained by using an Abbe flap only. The balance between the lips was also improved. The technique is recommended in patients of secondary deformity of cleft lip with severe shortage and thinness of the lip vermilion.

Adult↗
PubMed1990

Baroreflex adaptation and resetting on the control of arterial pressure.

In anesthetized and vagotomized dogs, the carotid sinuses were vascularly isolated to control and adjust the carotid sinus pressure (CSP). In 10 animals, we first observed the changes in systemic arterial pressure (SAP) during CSP holding at different levels. Thereafter, the CSP was lowered to 40 mmHg and increased to 180 mmHg in a ramp fashion to obtain the CSP-SAP baroreflex function curves. The system was initially stabilized at a sinus holding pressure (HP) of 100 mmHg and an average SAP of 107.5 mmHg. During a 15 min HP at 50 mmHg, the SAP elevated to 119.4 mmHg at the beginning and then adapted downward to a stable level of 107.2 mmHg in 5 min. On the other hand, a change of HP to 150 mmHg caused a SAP decrease to 69.0 mmHg and then adapted upward to a quasi-steady level of 87.5 mmHg in 5 min. The CSP-SAP curves constructed by logistic function analysis from the ramp protocol were also significantly affected by the HPs. When the CSP-SAP curve following a HP of 100 mmHg was used as a control, the curve was shifted to the left and to the right following a HP of 50 and 150 mmHg, respectively. There were significant increases in the threshold, midpoint and saturation pressures as the HP was elevated. The degree of acute resetting (delta threshold pressure/delta HP) was calculated to be 33.0% (16.5/50) and 55.4% (27.7/50) for a change of HP from 100 mmHg to 50 mmHg and to 150 mmHg, respectively. However, the resetting was characterized by a parallel shift of the CSP-SAP curves without significant changes in the baroreflex sensitivity or gain. As the acute adaptation and resetting are correlated using a graphic analysis, we hypothesize that the baroreceptors can recognize a new pressure level within minutes. The inherent ability incurs downward and upward adaptation as well as resetting at lower and higher holding pressure, respectively.

Adaptation, Physiological↗
PubMed1989

[Lateral calcaneal artery flap].

The lateral calcaneal artery flap provides a simple and reliable option for reconstructing the posterior heel defect. In our 10 cases including 3 diabetic patients, there was no flap necrosis, but one had the problem of wound healing. In another case, the skin graft over the flap donor site failed to take. All patients have protective sensation on the flap area, and 7 ambulatory patients can engage in a normal daily activity. Numbness over the lateral foot does not cause any trouble. There are a lot of spoke injuries in our 6-million-motorcycle country. When the conservative treatments do not achieve a satisfactory result, the lateral calcaneal artery flap should be the best surgical intervention for the defect less than 5 cm in diameter with bone or tendon exposure.

Adolescent↗
PubMed1989

Functional voiding disorders in women.

From July 1986 to Dec 1987, 78 women complaining of frequency, urgency, dysuria and suprapubic discomfort were evaluated at our clinic. Their ages ranged from 20 to 68 (mean age: 38.2). The patients who were noted to have evidence of pyuria, neurological or gynecological abnormalities were excluded from the study. Urodynamic examinations including uroflowmetry, cystometry (CMG), urethral pressure profiles (UPP) and electromyography (EMG) of the external urethral sphincter were performed. The results revealed low flow rates in 56 patients (71.8%), non-relaxation of the external sphincter during voiding in 55 patients (70.5%), unstable bladder in 6 patients (7.7%) and a high maximal urethral closure pressure (MUCP) (greater than 80 cmH2O) in 44 patients (56.4%). The average volume of the cystometric capacity (250 +/- 86 ml) was decreased. The association between the low flow rate, non-relaxation of the external sphincter and a high MUCP was statistically significant. Urethral hypersensitivity has been recognized as being the major cause of these symptoms.

Adult↗
PubMed1987

Left ventricular diastolic function in hypertrophic cardiomyopathy: assessment by radionuclide angiography.

Diastolic left ventricular function was studied in 20 patients with obstructive hypertrophic cardiomyopathy, 10 with apical hypertrophic cardiomyopathy, and 20 control subjects. The left ventricular time-activity curve was filtered using Fourier expansion with 4 harmonics. The first and second derivatives of the filtered curve were used to define various parameters of the left ventricle. Isovolumic relaxation period and time to peak filling rate were prolonged in obstructive hypertrophic cardiomyopathy and apical hypertrophic cardiomyopathy (101.56 +/- 44.81 msec, 105.19 +/- 45.27 versus 72.19 +/- 29.36 (CS) P less than 0.05; 169.70 +/- 50.73 msec, 173.83 +/- 50.53 versus 138.02 +/- 29.54 (CS) P less than 0.05, respectively). Rapid filling period, diastasis, atrial contraction period, time to peak filling rate-isovolumic relaxation period, and filling fraction of diastasis were not significantly different in these groups. Fasting filling fraction was 11% lower in hypertrophic groups than in control subjects. The filling fraction of atrial contribution was 12% higher in hypertrophic groups. We conclude: Isovolumic relaxation period, rapid filling phase, and diastasis atrial contraction period can be clearly defined by this technique. Impaired relaxation is an important determinant of decreased left ventricular filling in patients with obstructive hypertrophic cardiomyopathy and apical hypertrophic cardiomyopathy. Prolonged time to peak filling rate is mainly due to increased isovolumic relaxation period in hypertrophic patients. Atrial contraction contributes to more stroke volume in patients with hypertrophic cardiomyopathy.

Adult↗
PubMed1985

Location of intravenously injected kanamycin sulfate in the middle ear mucosa.

Twelve guinea pigs were treated with intravenous kanamycin sulfate (KM) and sacrificed 2, 5, 10, and 30 min later to investigate its location in the middle ear mucosa, especially in the Eustachian tube (ET). Immunological examinations evidenced KM in the epithelial and subepithelial layers of the ET on each occasion of observation. But, it was never recognized in the tubal gland. These observations might indicate that clinically used drugs easily get to the ET except for the tubal gland which might have some barrier mechanism against foreign bodies.

Animals↗
PubMed1985

Age-related changes in deformability of human erythrocytes.

The present study was designed to further the characterization of age-related changes in the deformability of human erythrocytes. The top (approximately young) and bottom (approximately old) 10% fractions of density-separated red cells from ten normal donors were subjected to graded levels of shear stress in a rheoscope. Measurements were made of steady-state elongation (cells tank treading in a state of dynamic equilibrium) and the time course of shape recovery following abrupt cessation of shear. In parallel with the rheologic experiments, several physical and chemical properties were assayed to determine correlates of mechanical properties. These included mean cell volume, mean corpuscular hemoglobin concentration, type A1 hemoglobin, glucosylation of membrane proteins, and membrane phospholipid and protein concentration. The microrheologic observations revealed that only about 90% of the old cells retained their capacity to tank tread. However, the tank-treading cells elongated less than their younger counterparts at corresponding levels of shear stress, thus demonstrating a reduced level of deformability. Further analysis of the data indicates that increases in membrane viscosity and elastic modulus along with a significant loss in excess surface area contribute to the limitation of the ability of the older cells to change shape.

Adult↗
PubMed1984

Respiratory viruses and Mycoplasma pneumoniae infections at the time of the acute exacerbation of chronic otitis media.

The present study was undertaken to ascertain whether or not patients with chronic otitis media are infected with viruses or Mycoplasma at the time of sudden increase in otorrhea. From 26 patients with acute exacerbation of chronic otitis media, sera were collected at the time of sudden increase in otorrhea and three to four weeks later. These paired sera were examined for antibody titer to respiratory viruses (21 species) and Mycoplasma pneumoniae. Of them, influenza B virus and RSV infections were demonstrated in four and two cases, respectively. Examinations showed no infection in 10 control cases without acute exacerbation. In 36 cases of acute exacerbation of chronic otitis media, attempts were made to isolate viruses and Mycoplasma pneumoniae from the pharynx and otorrhea. Consequently, influenza B virus was detected in pharyngeal mucous scrapings in two cases and RSV in one. The probability of respiratory virus infection leading to acute exacerbation of chronic otitis media appears to be lower than that provoking acute otitis media in children and infants. However, the present data suggest that the development of respiratory virus infection in patients with chronic otitis media may cause an increase in the otorrhea, eventually resulting in an acute exacerbation of inflammation.

Antibodies, Bacterial↗
PubMed1984

Behavior of radionuclides in sanitary landfills.

his study was undertaken to evaluate the possibility of disposing low-level radioactive waste in sanitary landfills with leachate containment to prevent environmental releases. To meet this objective, two simulated landfills, each 200 l. in volume and containing 55 kg of municipal refuse, were operated in the laboratory with simulated rainfall additions for a 9-month period to observe the extent to which radio-cobalt, -cesium, -strontium and tritium were leached into the liquid phase. One of the units was operated with leachate recycle, the other as a single pass control. Liquid samples were analyzed weekly for 3H, 58Co, 85Sr and 134Cs tracers. Weekly analyses were also performed for approximately 30 parameters to define the degree of stabilization of the waste. Major parameters included BOD, COD, pH and concentrations of specific organics, metals and gases. Concentrations of stable cobalt, strontium and cesium were also measured periodically. Soluble radioactivity levels in both systems were reduced by factors of 50 for 58Co, 5 for 85Sr and 7 for 134Cs, taking radioactive decay and dilution into account. Some radionuclide removal from the liquid phase was associated with major chemical changes in the landfills that occurred within 80 days for the control system and within 130 days for the recycle unit. Observed acid, sulfide, and CO2 concentrations suggested mechanisms for removing some of the radionuclides from leachate. Detection of 3H in the off-gas indicated that less than 1% of tritiated waste became airborne. The waste in the leachate recycle unit was more completely stabilized than in the control unit.

Environmental Pollution↗
PubMed1984

Diphenylmethane diisocyanate (MDI)-induced asthma: evaluation of the immunologic responses and application of an animal model of isocyanate sensitivity.

A worker developed two episodes of severe asthma 90 min after cutting a polyurethane plate made of diphenylmethane diisocyanate (MDI) using a rapidly turning carbide blade. Intradermal skin testing with MDI-human serum albumin (MDI-HSA) and p-tolyl isocyanate-HSA (p-TMI-HSA) were positive at 0.002 mg/ml. Control subjects showed no reaction at 2 mg/ml. Bronchial provocations of the worker with MDI-HSA and p-TMI-HSA, made 1 year after the occupational asthmatic episode, were negative at 10 mg/ml. Bronchial reactivity to methacholine decreased toward normal during a 2-year follow-up. RAST using MDI-HSA or p-TMI-HSA were strongly positive when compared with binding by sera from atopic controls which contained the same amount of total IgE. RAST titres decreased during a 1-year follow-up. In the MDI-HSA RAST, inhibition studies indicated specificity of antibodies for MDI-HSA. In the p-TMI-HSA RAST, p-TMI-HSA was a very effective inhibitor whereas MDI-HSA was not. These results indicated the formation of at least two distinct groups of IgE antibodies: those reactive with MDI, and those reactive with p-TMI determinants. Guinea pigs immunized with MDI formed antibodies with specificities similar to those of the patient. We conclude that the worker had occupational asthma accompanied by the formation of specific IgE antibodies of the specificities. The causal relationship of the antibodies to the occupational asthma remains uncertain.

Animals↗
PubMed1984

Effects of higenamine on isolated heart adrenoceptor of rabbit.

In the present study, effects of higenamine on various mechanical parameters of rabbit left atria as influenced by propranolol were investigated and compared to those of epinephrine. The following results are obtained: Higenamine, in a dose-dependent manner, increased the rate of tension development and shortened both the time to peak tension and the total duration of contraction. These effects of higenamine were competitively blocked by propranolol. The pA2 values of higenamine and epinephrine against propranolol were 8.58 +/- 0.14, 7.50 +/- 0.82 respectively, and the slopes by Schild plots were 0.97 and 0.99 with higenamine and epinephrine, respectively. The results indicate that the positive inotropic action of higenamine is likely due to stimulation of cardiac adrenoceptors.

Alkaloids↗
PubMed1983

Ototoxic effect of an aminoglycoside drug on an immature inner ear.

In order to investigate to what extent an immature inner ear is injured by external causes, the effect of Kanamycin on an immature cochlea was studied in mice by using scanning and transmission electron microscopes. Our results showed that immature cochleae are more highly susceptible to injury than mature cochleae, especially when the Nuel's space and the Corti tunnel open. It is suggested that in humans, during the stage corresponding to the above period, that is, in about the third gestational month, the inner ear is highly susceptible to injury by external causes.

Animals↗
PubMed1982

Linear growth of chronic asthmatic children: the effects of the disease and various forms of steroid therapy.

The effects of asthma per se and of various oral steroid-treatment schedules on linear growth in 231 children with chronic severe asthma (6.2-16.2 years of age) were evaluated. Asthmatic children who had never received steroids and those who received occasional steroids, had comparable growth retardation, averaging approximately 1 standard deviation (s.d.) below their age- and sex-specific predicted means. Children who had been treated for 2 years or longer with alternate-day or daily steroids also did not differ from each other, with both groups averaging approximately 2 s.d. below their predicted means. Growth stunting, intermediate in severity, was found in children treated with frequent intermittent steroids. For groups with steroid medication-histories of never, occasional, intermittent, alternate-day and daily, the percentage of children with 2 or more s.d. below their predicted heights were 25, 17.4, 28, 50 and 45.5 respectively. The duration and dosage of daily steroid-treatment correlated positively with severity of growth retardation. In addition to norms, the children were also compared with a healthy, same-sex sibling and with predictions from their parents' heights. Regardless of the comparison used, the results were similar. Since genetic and socio-economic factors are controlled by the latter two comparisons, the data indicate that these factors played no role in growth retardation in these children. Growth retardation in asthma appears to be due to the disease itself, and is accelerated by steroid therapy.

Adolescent↗
PubMed1982

Ototoxicity of the anticancer drug cisplatin. An experimental study.

Cisplatin was administered to guinea pigs. Hearing function was tested using ABR, and morphological studies were conducted by scanning and transmission electron microscopy. The following findings were made. (1) The susceptibility to cochlear damage by cisplatin was dose dependent. (2) At the same dose, damage was most severe in the lower turns, particularly in the second turn. This tallies with the high tone loss. (3) Mainly the outer hair cells are the site of the damage and the inner hair cells are rarely damaged. (4) The first row of the outer hair cells tend to be more severely damaged. (5) Variation of the stria vascularis was moderate compared with the damage to the organ of Corti. (6) A tendency of recovery was observed in ABR in some animals after they were given 2 mg/kg/day cisplatin intramuscularly consecutively for 8 days.

Animals↗