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Biomedical subjects

W Chu

Publications and source records attributed to W Chu.

At least 127 records · Page 7Linked to original sources
PubMed1990

Keratoconjunctivitis sicca and corneal ulcers.

We reviewed the records of 56 patients (109 eyes) who satisfied our criteria for keratoconjunctivitis sicca (KCS) to determine factors associated with the development of sterile corneal ulcers. The patient's age, sex, and associated local ocular surface and/or systemic disease were studied. We found a statistically significant association between the development of corneal ulceration and the presence of an underlying condition or disease state, especially chronic rheumatoid arthritis. Patient sex and age were not significantly associated with the development of corneal ulceration. We present three case histories that illustrate the complications that arise in managing KCS plus an associated disease and methods of management.

Adult↗
PubMed1989

Serum albumin and its acid hydrolysis peptides dominate preparations of mineral-bound enamel proteins.

Serum albumin is a major noncollagenous protein component of bone, dentine, and, according to our results, enamel. Preparations of mineral-bound proteins from porcine developing enamel contain a single 67 kD protein at neutral pH or three proteins (67, 63, and 53 kD) at low pH that were assumed to be enamelins, a minor class of enamel proteins. A more complete analysis of these proteins in this study showed that they were derived from porcine serum albumin (PSA). This was demonstrated by amino acid analysis, by N-terminal sequence analysis, by immunoblot studies using an anti-PSA antibody, and by SDS-PAGE analysis of the acid hydrolysis, cyanogen bromide, and tryptic peptides. Examination of enamel at different developmental stages showed that PSA deposited in enamel from the enamel organ and from the dentine during development, not during the dissection process. These results indicate that true enamelins must represent a very small fraction of the total mineral-bound protein matrix in porcine developing teeth, and this has important implications on the role of mineral-bound proteins during mineralization of enamel.

Amino Acid Sequence↗
PubMed1986

Histologic changes and arrhythmogenicity after discharge through transseptal catheter electrode.

Ventricular tachycardia commonly arises within the intraventricular septum and successful catheter ablation of septal tachycardia might be enhanced by transseptal electrode placement. We have evaluated the safety of a transseptal ablation procedure. Arrhythmogenicity and histology were examined after high-energy capacitor discharges were delivered to an intracavitary cathode-anode pair placed on opposite sides of the interventricular septum in pentobarbital-anesthetized dogs. After two discharges of 200 or 100 J proved lethal, paired discharges of 30 or 50 J (10 dogs) or a single discharge of 100 J (four dogs) was used to induce 28 lesions. Acute rhythm changes and risk of induction of ventricular tachycardia by programmed stimulation were measures of arrhythmogenicity. Gross and histologic examination of the hearts after 20 min to 28 days allowed characterization of the evolution of lesions. The conduction system in nearby and remote locations was extensively examined in four dogs. Refractory ventricular fibrillation developed with paired shocks at 200 or 100 J. At lower energy levels, acute ventricular fibrillation occurred with 12 of 20 shocks (60%), but defibrillation was consistently achieved. After ablation, no dog had ventricular tachycardia or fibrillation induced with programmed stimulation. Matching anodal and cathodal lesions spanned the septum without perforation in 10 of 16 dogs, and the lesions were of similar histology. Each contained central areas of hemorrhage surrounded by a region of coagulation necrosis merging with normal myocytes peripherally. There was necrosis and edema without inflammation at 20 min, acute inflammatory cell infiltration at 1 to 2 days, and myocyte replacement by granulation tissue after 6 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Marker chromosomes: cytogenetic characterization and implications for prenatal diagnosis.

Satellited marker chromosomes were identified in four individuals from unrelated families; one was first encountered in cultured amniotic fluid cells obtained for prenatal diagnostic studies. We present cytogenetic characterization of these marker chromosomes and clinical findings in the individuals carrying them. Identification of a marker chromosome in amniotic fluid cell cultures presents problems in genetic counseling, as it is often difficult to determine the clinical significance of such a finding. Chromosome-banding techniques now allow the precise identification of satellited marker chromosomes originating from chromosome 15. Presence of a supernumerary bisatellited der(15) marker chromosome containing the proximal long arm of 15 has been associated with mental and developmental retardation. Application of chromosome-banding techniques was useful in characterization of the marker chromosomes and providing prenatal genetic counseling.

Adult↗
PubMed1980

Duration of the hypotensive action of nitroglycerin ointment in ambulatory subjects utilizing an automatic blood pressure recording device.

Nitroglycerin ointment (GTNO) is widely used in the treatment of angina pectoris. In order to use this agent effectively, its duration of action must be known. This study was designed to determine how long GTNO acts in the ambulatory subject. A portable blood pressure measuring device was used for this purpose. 10 normal subjects were studied on 3 consecutive days: day 1, control (c); day 2, placebo (P); day 3, GTNO. The dose of GTNO used was the amount required to produce a greater than 10-mm Hg fall in systolic blood pressure (BP). There was no signifiant difference in BP, heart rate (HR) or BP X HR product between C and P. On day 3 (GTNO), a fall in BP (p less than 0.001) occurred when compared with C and P, and this change remained significantly different form C and P over a period of 7 h. Since these data suggest that the action of GTNO is maintained for at least 7 h, we conclude that its administration at this interval should be effective in the relief of angina pectoris.

Adult↗
PubMed1979

Ocular surface manifestations of the major viruses.

The ocular surface is often the first site of involvement by viral infections. Background information, clinical presentations, and current treatment of three major viruses--herpes simplex, varicella-zoster, and adenovirus, have been presented in detail in this chapter. The effects of adenoviruses are usually transient and may be regarded as a nuisance. Infection with herpes simplex or varicella-zoster may lead to prolonged activity of the disease and life-long treatment with occasional loss of useful vision. It is apparent that our understanding of the clinical behavior of the major viruses has increased in recent years. Therapeutic criteria and modalities have also improved for some of the complications of the viruses. Much work needs to be done for some of the other manifestations, i.e., failure of reepithelialization, stromal melting, scarring, vascularization, and inflammation.

Adenovirus Infections, Human↗
PubMed1978

Oncocytoma of the parotid gland with malignant change.

We report on a patient with preinvasive malignant change in an oncocytoma of the right parotid gland. Histologic transition from benign morphology to malignant cellular atypia, to our knowledge described only once previously in the literature, was present. Satisfactory results from wide surgical resection and postoperative radiotherapy in our patient serve as additional experience in the treatment of this rare malignancy.

Adenoma↗
PubMed1978

Restoration of pharyngoesophageal continuity with a replaceable prosthetic conduit: a new method.

Treatment of carcinomas of the upper aerodigestive tract by high dose radiation and wide surgical resection result in large tissue defects. When the inferior pharyngeal constrictor and the cricopharyngeus muscles are removed, a replaceable prosthetic conduit can be used effectively to reestablish pharyngoesophageal continuity. This prosthesis can be readily fabricated and obviates the need for extensive reconstructive operations in suitable candidates.

Esophageal Neoplasms↗
PubMed1978

Results in suprahyoid, modified radical, and standard radical neck dissections for metastatic squamous cell carcinoma: recurrence and survival.

Two hundred sixty-one patients who underwent three types of neck dissection for cervical lymphadenopathy in association with squamous cell cancer of the head and neck are analyzed retrospectively. Patients were grouped into those with histologically negative nodes and those with histologically positive nodes. Statistical analyses for neck recurrence and survival rates were made using the sampled permutation method. The results show that suprahyoid neck dissection is associated with an unusually high recurrence rate in the neck in patients with histologically negative nodes. Modified radical neck dissection and standard radical neck dissection are equivalent with regard to recurrences in the neck and five year survival rates when the disease is above the juguloomohyoid lymph node group. The study suggests that simple upper neck dissection is contraindicated in patients with negative or positive nodes and that modified radical neck dissection can be used in selected patients instead of the formal radical neck operation.

Adult↗
PubMed1978

A clinical study of slow-releasing artificial tears.

The slow-releasing artificial tear (SR-AT) is a soluble polymer in solid form. Placed in the inferior cul-de-sac and allowed to dissolve, it is used to treat dry-eye patients. The SR-AT was studied in two phases. The short-term cross-over study of 40 patients was completed in October 1976. The long-term open study is still in progress. Of 37 patients who started the long-term study, 18 are still using the inserts-a study retention of 49%.

Cellulose↗
PubMed1978

Hemodynamic correlates of echocardiographic aortic root motion. Observations on normal subjects and patients with idiopathic hypertrophic subaortic stenosis.

In ten normal subjects, we observed an initial hump in the aortic root echocardiogram after the onset of the QRS complex, following which a sharp anterior motion was noted. The onset of the anterior motion of the aortic root coincided with the onset of the upstroke of the aortic root pressure pulse and the onset of the velocity signal in five of seven patients with coronary arterial disease; in the other two, the anterior aortic motion followed the onset of the pressure and velocity signal by 10 msec. The aortic root echocardiogram was abnormal in patients with idiopathic hypertrophic subaortic stenosis; the slope (normalized for the scales of time and depth) in early systole was steeper and in the latter part of systole was flatter than normal in these patients. The slope in early diastole was flatter and the slope due to atrial contraction was steeper in the patients with idiopathic hypertrophic subaortic stenosis than in the normal subjects. These features were consistent with rapid ejection in early systole and slow filling in the early phase of ventricular diastole in idiopathic hypertrophic subaortic stenosis. Fourier analysis of the wave form of the aortic root allowed separation between patients with idiopathic hypertrophic subaortic stenosis and normal subjects.

Adult↗
PubMed1977

Parapharyngeal growth of parotid tumors: report of two cases.

Two patients with parapharyngeal pleomorphic adenomas of the parotid gland, one malignant and one benign lesion, were successfully treated operatively. Deep lobe parotid tumors may occasionally grow along the stylomandibular tunnel into the parapharyngeal region. Since the opening of the tunnel is narrower and less distensible than the parapharyngeal region, the tumor assumes a dumbbell shape. The patients have an intraoral mass or asymmetry of the palate, with difficulties in swallowing or phonation. The diagnosis is suspected on bimanual examination, and puncture biopsies should be done to establish a histologic diagnosis. Operative removal of the parotid gland with facial nerve preservation is recommended. External, transoral, and combined approaches can be employed. Enlargement of the opening of the stylomandibular tunnel by cutting the styloid process of the mandible is necessary for complete tumor removal. Rupture of the capsule should be avoided. Results are rewarding with proper management.

Adenocarcinoma↗