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Biomedical subjects

C C Chu

Publications and source records attributed to C C Chu.

At least 163 records · Page 9Linked to original sources
PubMed1982

Racial and geographic differences in the psychopathology of schizophrenia.

The authors compared the psychopathology of black and white and of rural and urban schizophrenic patients. Using a structured interview, psychiatrists rated 273 schizophrenic patients consecutively admitted to seven hospitals and mental health centers over 3 1/2 years. Results indicate that important symptoms were more severe in black than in white schizophrenic patients: black patients were more angry, impulsive, hallucinating, dysphoric, and asocial. A greater number of important symptoms were found to be more intense in rural than in urban schizophrenic patients: rural patients were more angry, aggressive, silly, negativistic, and uncooperative, but urban patients were more anxious, rigid, ambivalent, and asocial.

Adolescent↗
PubMed1982

Symptomatology differentials between urban and rural schizophrenics.

The frequency of symptoms between urban and rural schizophrenic patients was compared in 275 consecutive admissions of schizophrenics, who were rated on two rating scales by psychiatrists, using a structured interview. There were significant differences between urban and rural schizophrenics; rural patients were more frequently apathetic, blunted, labile, angry, aggressive, negativistic and uncooperative, while urban schizophrenics were more often anxious, rigid, ambivalent, disoriented, conceptually disorganised and asocial. Significant symptom differences were also found for only older or younger schizophrenics.

Adolescent↗
PubMed1981

An in-vitro study of the effect of buffer on the degradation of poly(glycolic acid) sutures.

The tensile strengths of poly(glycolic acid) (PGA) sutures immersed in buffered and unbuffered aqueous media were compared. The media used were an unbuffered physiological saline solution (pH = 5.0) and a phosphate-buffered physiological saline solution (pH = 7.4). PGA samples were immersed for various periods in each medium, and kept at 37 +/- 1 degree C in a constant temperature oven. The tensile strengths of the specimens were tested immediately after removal from the medium. Stress-strain curves of the specimens were expressed in terms of the stress unit "tenacity," commonly used in the study of fibrous polymers; it is an appropriate unit for materials of fibrous nature. These stress-strain curves were investigated as functions of buffering and duration of immersion. Degradation reduced the tensile strength of PGA more in the buffered saline solution than in the unbuffered. This higher rate of degradation in the buffered solution might be due to the presence of Na2HPO4, which removed the degradation products, shifted the reaction toward increased hydrolosis, and accelerated the loss of tensile strength in the PGA. A continuous decrease in the pH of the unbuffered solution supports this explanation. Tied-chain segments of macromolecules, a theory widely used in the study of mechanical strength of fibrous polymer may be the key to a comprehensive description of the degradation phenomenon of PGA.

Biodegradation, Environmental↗
PubMed1981

The in-vitro degradation of poly(glycolic acid) sutures--effect of pH.

Tensile strength of poly(glycolic acid) suture (PGA) of size 2-0 was examined as a function of three pH levels, 5.25, 7.44, and 10.09 of the buffer. Cord and yarn grip was used to eliminate grip-induced failure of breaking strength tests. It was found that Dexon sutures degraded significantly faster in pH = 10.09 buffer than the other two lower pH buffers. There was no significant difference in degradation rate at pH = 5.25 and 7.44. At 7 days, PGA sutures lost almost half of its original tensile strength at pH = 10.09, while the same sutures still remained more than 95% of their original breaking strength at buffers of pH = 5.25 and 7.44. After 21 days, no trace of sutures could be detected in the buffer of pH = 10.09 while about 20% strength still remained in the buffers of pH = 7.44 and 5.25. Cage effect in the crystalline phase and pH dependent hydrogen bonding were introduced to explain the difference in degradation phenomenon of PGA at buffers of various pH.

Buffers↗
PubMed1981

Mechanical properties of suture materials: an important characterization.

A comprehensive and systematic study of the stress-strain behavior of seven synthetic absorbable and nonabsorbable sutures was conducted. The purpose of the study was to provide detailed mechanical information on suture materials in order to assist surgeons in their selection of adequate sutures for specific surgical applications. The use of a yarn grip, newly designed specifically for fibrous materials, eliminated several difficulties imposed by conventional grips, and resulted in more dependable mechanical properties. A wide range of stress-strain characteristics was observed in the tested sutures. Suture materials of similar nominal properties may behave quite differently in their stress-strain relationship. This was true of sutures of the same chemical nature as well as of different geometric construction, such as Ethilon vs. Nurolon. Larger differences in stress-strain curves were observed after the yield point with yarn grips than with conventional grips. The unique shape of the stress-strain curves, and the associated data derived from them, provide better information in the discrimination between suture materials.

Elasticity↗
PubMed1979

Evaluation of sunlight stability of polyurethane elastomers for maxillofacial use. II.

The effect of selected UV stabilizers on the stability of mechanical properties of a polyurethane material, Calthane ND2300, was evaluated. The addition of UV stabilizers prolonged the service life of the systems studied but did not achieve completely satisfactory results. The tensile strength and modulus of elasticity decreased after extended exposure to UV. The rate of decrease, however, was much less for the specimens with UV stabilizers. The polyurethane system that contains a mixture of a UV stabilizer and an antioxidant is considered to be the best of the groups tested, in terms of the percentage of retention of tensile strength and modulus of elasticity. It was also found that elongation at break was increased when the duration of UV aging was increased. This phenomenon occurred in all the systems, with or without UV stabilizers, and can be understood in terms of the concepts of the fragmentation of macromolecules that resulted from UV aging. The physical appearance in conjunction with mechanical property tests are needed to ensure the successful performance of any UV stabilizer.

Chemical Phenomena↗
PubMed1978

Evaluation of sunlight stability of polyurethane elastomers for maxillofacial use. I.

The evaluation of the efficiency of polymer additives with special emphasis on uv absorbers and antioxidants in polyurethane elastomers has been completed. Aliphatic polyurethanes were chosen for this study because their properties closely relate to the requirements of maxillofacial prosthesis. The polyurethane elastomers were either synthesized by ourselves or formulated according to the manufacturer's recommendation. Eleven different types of uv absorbes, coupled with one antioxidant, were incorporated into the polyurethane systems. The Atlas twin-lamp carbon arc Weatherometer was used as the source of uv. The samples were periodically withdrawn for examination of yellowing and tackiness. It was found that, although the incorporation of uv stabilizers enhanced the uv resistance of polyurethanes, the problem of tackiness resulting from uv aging was not solved satisfactorily. The phenomenon of yellowing, however, was significantly improved, mainly due to the aliphatic structure of polyurethanes. The most promising uv absorbers are Tinuvin 770 and the combination of Tinuvin 328, ZnO, and an antioxidant. Their effectiveness in other polyurethane systems is not known and further research is underway to explore this field. Hopefully, these findings will greatly assist the successful application polyurethane elastomers in maxillofacial prosthesis.

Biocompatible Materials↗
PubMed1974

Atmospheric corrosion.

A model of electrolytic corrosion is developed. It is shown that electrically conducting channels threading through the oxide layer and connecting anodic and cathodic areas, obey the equation for a reactant being catalyzed by its product. The resulting autocatalytic equation is compared with available experimental data and found to be widely applicable and capable of unifying many experimental observations.

Journal Article↗
PubMedDate not supplied

The effect of annealing treatments on the tensile properties and hydrolytic degradative properties of polyglycolic acid sutures.

The purpose of this research was to examine the effect of annealing treatments on the mechanical properties of polyglycolic acid sutures, and their subsequent influence on PGA degradation properties. An attempt was made to develop a better understanding of the degradation mechanism of synthetic absorbable sutures, including the relationship of their structure, morphology, and mechanical properties. PGA sutures were annealed under selected axial strain (freely hung, 0%, 1%, 10%), at four temperatures (150 degrees C, 170 degrees C, 180 degrees C, 190 degrees C), and two times (5 and 20 min). The annealed PGA specimens were then subjected to hydrolysis in phosphate-buffer solutions (pH = 7.4) for up to 28 days at 37 degrees C. Tensile properties were used to evaluate the effect of annealing treatments. The data were subjected to statistical analysis using the SAS system. All of the one-, and many of the two- and three-factor interactions were found to be statistically significant. Annealing treatments did alter the mechanical properties of PGA sutures, as well as their degradation properties. Except for the increase in tenacity of samples with increasing percent extension, all other respects of the annealing treatments resulted in lower tenacity and breaking elongation when compared with the control samples. Sutures that have been exposed to any level of axial tension during annealing, however, exhibited a lower rate of hydrolytic degradation than the freely hung suture samples. The reduction of the characteristics of fiber structure due to the tendency of the tie-chain molecules to acquire the less constrained conformations and thus to bring the crystal blocks they connect back to the original arrangement before drawing is believed to be responsible for the freely hung specimens to behave quite differently from the clamped and stressed PGA samples.

Hydrolysis↗
PubMedDate not supplied

The autonomic-related cortex: pathology in Alzheimer's disease.

Alzheimer's disease (AD) causes progressive deterioration of cognition and behavior. Memory dysfunction is the hallmark, but there are also changes in behavior, emotion and autonomic functions, which cannot be explained simply as a consequence of memory impairment. These observations suggest that the natural disease process of AD involves not only memory-related neural structures, but also specific neural systems related to other behaviors, emotion and autonomic functions. Since recent evidence has indicated a primary role for ventromedial frontal (VMF) cortex in such functions, we examined laminar distribution of neurofibrillary tangles and Alz 50 immunoreactive neurons in subdivisions of VMF cortex in 20 AD patients and seven age-matched controls. The densities of pathological changes were: (i) highest in the posteromedial mesocortical regions, particularly Brodmann's area 25 (A25), posterior orbitofrontal cortex (POF) and anterior insula (AI); (ii) of comparable severity between posteromedial mesocortical regions and most temporal cortices, excluding only the entorhinal cortex and temporal pole; and (iii) located predominantly in layer III and especially layer V. Further analysis demonstrated selective pathology in layer V of A25, POF and AI that would disrupt direct cortico-autonomic projections. This is the first study to detail severe AD pathology in these autonomic-related cortices, which could contribute to the behavioral changes, emotional disturbance and autonomic dysregulation that often accompany AD.

Aged↗
PubMedDate not supplied

Bicomponent vascular grafts consisting of synthetic absorbable fibers: Part II: In vivo healing response.

The objectives of this research were (1) to determine whether the use of partially absorbable vascular grafts would improve their nonthrombogenic performance and whether they are more prone to aneurysmal dilation and subsequent failure in vivo, and (2) to find out the relationships, if any, between these in vivo and the previously reported in vitro data with an emphasis on how the in vitro changes in fabric structure and properties related to these in vivo data. Bicomponent vascular fabrics were made from Dacron and polyglycolic acid (PGA) yarns with a range of composition ratios of the PGA to Dacron. Both woven and single Jersey knit fabrics were made, and implanted in dogs for 4 months. The following findings and relationships were obtained. (1) The bicomponent vascular fabrics resulted in a full-wall healing in the thoracic aorta of dogs. All bicomponent vascular grafts in survived dogs exhibited 100% patency, no thrombus or aneurysmal formation, no hematoma or seroma around the grafts, and no fibrin coagula in the inner capsules. The gross morphology of the regenerated tissues was very similar visually to the adjacent original arterial tissue. Histologically, the luminal surface was lined with a layer of endothelial cells with myofibroblasts, fibroblasts, and collagens underneath. (2) The extent of the full-wall healing depended on the type of fabric structure, the concentration of absorbable yarns, the location of absorbable yarns (for the woven group only), and initial water permeability. It is believed that the concentration effect was related to the level of macrophage activation from the degradation products of the absorbable yarns, while the location effect was attributed to the various types of fabric structure change on the degradation of the absorbable yarns. (3) In general, the knitted group (K), was better than the woven group (W). K3 showed the best in vivo performance in the knitted group. (4) In the woven group, W3 was the best. The incorporation of absorbable yarns in the weft direction of the bicomponent fabrics (W3) resulted in a velourlike, loose and porous fabric surface for facilitating tissue ingrowth. The placement of absorbable yarns in the warp direction (W1), however, did not show this unique surface morphology. Calcification was, however, occasionally observed in the woven samples with low initial water permeability. These observed in vivo performances correlated well with our previously reported in vitro study.

Absorption↗
PubMedDate not supplied

[Neonatal chylous ascites: report of two cases].

Chylous ascites in neonates is an unusual and etiologically poor understood entity. Our first case was a female newborn who suffered from abdominal distension and recurrent vomiting after birth. The history, physical, laboratory, and radiologic evaluations were not diagnostic except the evidence of obvious ascites. Paracentesis was performed and ascitic fluid was obtained. She was later discharged on a strict low-fat medium-chain triglycerides formula. She was found to have continue increase in abdominal girth, poor growth and development, and respiratory distress in which led her to readmission at 8 months of age. Exploratory laparotomy was done in order to rule out an anatomical lesion in which may be obstructing the lymphatic flow; but no such lesion could be found. She expired at 1 year of age with chylothorax, chylopericardium and lobar pneumonia. The second case, a 37-day-old male baby, who was admitted because of right inguinal hernia. Milky ascitic fluid in the abdomen was incidentally found during herniorrhaphy. Analysis of the fluid revealed protein 1,616 mg/dl, glucose 487 mg/dl, and triglyceride 796 mg/dl. Culture of peritoneal fluid grew no bacteria. Other laboratory findings were: serum protein 4.8 mg/dl, and BUN 14 mg/dl. A plain film of abdomen and sonogram showed massive ascites. The infant was then put on Pregestimil with the hope that the medium-chain triglyceride formula would improve his condition. Since then the child's abdominal girth did not increase and he continued to growth and develop normally at 4 months follow up.

Chylous Ascites↗
PubMedDate not supplied

[Multiple intestinal hemangioma: report of two cases].

Hemangioma of the small intestine is a rare disease which is sometimes very difficult to diagnose because of its anatomical location. This report concerns two cases of multiple intestinal hemangiomas treated surgically. The first case was a four-year-old boy who suffered from recurrent abdominal pain and progressive hemorrhage from the gastrointestinal tract for four months. The character of his abdominal pain was non-specific. On physical examination, whole abdominal tenderness was evident. Serial laboratory and radiological examinations, including abdominal sonogram, barium enema, Tc-99m pertechnetate scan, upper gastrointestinal series failed to reveal abnormality. Multiple intestinal hemangiomas were found at exploratory laparotomy. The second case was a new-born suffering from fetal ascites. Abdominal sonogram, barium enema, voiding cystourethrography were performed without significant findings, and the diagnose of multiple intestinal hemangiomas was proved by laparotomy. In both, symptoms improved after segmental resection of the bowels. The purpose of this paper is to draw attention to the possibility of intestinal hemangioma as a source of recurrent abdominal pain, tarry stool or ascites in children.

Child, Preschool↗
PubMedDate not supplied

[Solitary diverticulum of ascending colon induced internal intestinal herniation: report of one case].

Colonic diverticula are generally multiple and occur most commonly in the descending and sigmoid colon. Solitary ascending colonic diverticulum is a rare pathology and presents several features which separate it from colonic diverticulosis. It is a true diverticulum. It is a congenital dysplasia that generally runs an asymptomatic course and becomes clinically important only when inflammatory, perforating, or hemorrhagic complications occurs and presents a difficult problem in diagnosis and management. An unusual case of 4 year old girl with solitary ascending colonic diverticulum was reported here. It caused internal intestinal herniation by forming an adhesion band with mesentery and the clinical course manifested as an acute intestinal obstruction.

Child, Preschool↗
PubMedDate not supplied

Epididymo-orchitis in an infant resulting from Escherichia coli urinary tract infection.

Epididymo-orchitis (EO) is said to be extremely rare in infants and children. It is usually diagnosed after scrotal exploration for symptoms which mimic manifestations between EO and torsion of the cord and its appendage. The pathophysiologic mechanisms for the development of EO are not well known. Although some causative agents of EO have been reported, in most cases there was no clear etiology. We report a 3-month-old male infant who had been well until the day prior to admission when irritability, left testicular swelling, scrotal erythema with a hot sensation were noted by his mother. He was treated medically after excluding the possibility of an emergent surgical condition (such as torsion of the cord and its appendage, or incarcerated hernia) by means of physical examinations, abdominal and inguino-scrotal sonography, laboratory studies, and testicular radionuclide scintigraphy. A catheterized sample of urine for culture yielded Escherichia coli. There was the possibility that the EO was caused by hematogenous rather than local spread from an infection of the urinary tract. He was treated with a 10-day course of intravenous cefazolin and amikacin. Following this, he improved clinically and a repeat catheterized urine sample remained sterile on culture. In addition, a bilateral inguinal hernia and hydrocele were detected by inguino-scrotal sonography and were operated on the 11th hospital day. He was discharged on the 16th day of hospitalization and remained well 11 months after discharge.

Diagnostic Imaging↗