Biomedical subjects
Publications and source records attributed to S Lam.
A 52-year-old woman developed persistent epiphora in her left eye after undergoing occlusion of the left puncta. Two attempts to reopen the puncta with a one-snip procedure and placement of punctal silicone plugs failed. The epiphora resolved and the puncta remained patent after the patient underwent a third one-snip procedure, supplemented with topical mitomycin during and after surgery.
The clinical records of 14 patients with posterior scleritis were reviewed to compare the diagnostic potential of computed tomography (CT) and magnetic resonance imaging (MRI) in this condition. None of these patients had evidence of collagen vascular or other systemic diseases. Done 13 times on 11 patients, CT was diagnostic for posterior scleritis in six patients on seven occasions. We used MRI six times in five patients, and it was not diagnostic for posterior scleritis in any patient. Thus, CT appeared to be more sensitive than MRI in the diagnosis of posterior scleritis. The CT results appeared comparable to ultrasonographic findings (obtained eight times in six patients) in the diagnosis of posterior scleritis. Both CT and MRI, however, detected signs of orbital pseudotumor in six and three patients, respectively. These findings support the concept that posterior scleritis and orbital pseudotumor may represent a continuum of the same disease process.
The performance of a novel bronchoscopic fluorescence imaging system was compared with conventional white light bronchoscopy with a data base of 328 biopsy-confirmed sites from 53 patients and 41 volunteers. The two methods were found to have the same specificity (94%); however, the sensitivity of the fluorescence system (72.5%) was found to be 50% greater than that of the white light bronchoscopy (48.4%) in detecting dysplasia and carcinoma in situ. The fluorescence system uses a nonlinear discriminant function combining the red and green image intensity values to form a pseudoimage that, when displayed on an RGB monitor, allows the detection and delineation of abnormal areas. In 15% of the patients with lung cancer, synchronous carcinoma in situ was found in addition to the large invasive cancer. Of the current smokers in this study, 40% had moderate dysplasia and 12% had severe dysplasia. For the ex-smokers 25% had moderate dysplasia, 6% had severe dysplasia, and 13% had carcinoma in situ. Fluorescence imaging may become an important adjunct to conventional bronchoscopic examination to improve our ability to diagnose and stage lung cancer more accurately.
Between Dec. 1, 1973, and May 30, 1989, 36 patients (37 eyes) with ocular toxoplasmosis seen at a uveitis clinic received quadruple therapy (pyrimethamine, trisulfapyrimidines, clindamycin and prednisone). The criteria for quadruple therapy were active lesions involving or threatening the macula or the optic disc, or a visual acuity of 20/70 or worse due to vitreous opacification caused by active inflammation. All but four of the cases showed improved vision. A total of 54% of the cases responded favourably within 2 weeks after the start of treatment, and 81% responded within 3 weeks. Patients took pyrimethamine for 1 to 2 weeks and received trisulfapyrimidines and clindamycin for 3 weeks, with a tapering course of orally given prednisone. The only complication was skin rash secondary to trisulfapyrimidine therapy, in four cases. None of the patients manifested diarrhea, pseudomembranous colitis or bone marrow suppression. The length of follow-up ranged from 1 month to 15.5 years. There were seven recurrences in five patients, five of which responded to a second course of quadruple therapy.
Eleven patients with Angelman syndrome (AS) and their parents from 5 families have been studied with high resolution chromosome analysis and molecular probes from region 15q11-13 in an attempt to elucidate the mode of inheritance in familial AS. No deletions were detected. All families were informative with a combination of different short arm cytogenetic markers. All sets of sibs inherited the same maternal chromosome 15, but in 3 families sibs inherited different paternal 15s. Analysis of 6 polymorphic DNA markers supported the conclusion that AS sibs inherit the same maternal 15, but often different paternal 15s. These data make autosomal recessive inheritance at a 15q11-13 locus very unlikely and support the hypothesis that familial AS is due to maternal transmission of a mutation within 15q11-13.
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Early detection of invasive and pre-invasive neoplasms of the aerodigestive tract will ultimately improve the management of patients with these lesions. This paper describes the use of quantitative fluorescence imaging of early squamous cell carcinomas in an animal model. Dysplasia, carcinoma in situ and invasive cancers were imaged exploiting tumour autofluorescence. Mapped biopsies were obtained from areas imaged determining a sensitivity of 100% and specificity of 80%. Autofluorescence imaging is an excellent method of detecting neoplasms of the aerodigestive tract.
BACKGROUND: Two cases of sympathetic ophthalmia occurring after noncontact neodymium:YAG (Nd:YAG) cyclotherapy have previously been reported. In each case, the patient had undergone filtering surgery in the exciting eye. Although in each case Nd:YAG cyclotherapy was the last surgery performed, the inciting event of sympathetic ophthalmia was unclear. METHODS: The authors studied three additional patients who developed sympathetic ophthalmia after Nd:YAG cyclotherapy for glaucoma. RESULTS: Two patients developed sympathetic ophthalmia 4 months after noncontact Nd:YAG cyclotherapy, and 1 patient developed sympathetic ophthalmia 18 months after contact Nd:YAG cyclotherapy. All patients had previous cataract extractions but no filtering surgery in the exciting eye. Clinical features included chronic iridocyclitis, choroidal folds, Dalen-Fuchs nodules, and optic disc edema. Combining these cases with the two previously reported cases, the incidence of sympathetic ophthalmia at our institution thus far is 5.8% (4 of 69) and 0.67% (1 of 150) after noncontact and contact Nd:YAG cyclotherapy, respectively. CONCLUSIONS: The incidence of sympathetic ophthalmia after Nd:YAG cyclotherapy is high compared with other ocular procedures. The clinician should vigilantly monitor patients after Nd:YAG cyclotherapy and report additional cases that may have occurred at other institutions.
A 77-year-old man with chronic conjunctivitis, acanthosis nigricans with pachydermatoglyphy, and pemphigus-like mucocutaneous lesions was found to have a well-differentiated bronchogenic squamous cell carcinoma. Histopathologic and immunofluorescence studies confirmed the diagnosis of paraneoplastic pemphigus. Skin lesions resolved with oral prednisone and azathioprine therapy, but the conjunctivitis and mucous membrane erosions persisted. The conjunctiva later became scarred with foreshortening of the fornices and development of symblepharon. External beam irradiation arrested the growth of the tumor but did not have any effect on the diseased conjunctiva and other mucous membranes. This case demonstrates that cicatrizing conjunctivitis with bullous mucocutaneous lesions may be a clinical sign associated with an occult neoplasm.
Fluorescence bronchoscopy was performed in 82 volunteers recruited from occupational groups at risk of exposure to asbestos and/or diesel fumes to determine whether differences in tissue autofluorescence between normal and malignant bronchial tissues can be used to improve the sensitivity of standard fiberoptic bronchoscopy in detecting dysplasic and carcinoma in situ (CIS). This study consisted of 25 nonsmokers, 40 exsmokers, and 17 current smokers with mean ages of 52, 55, and 49 yr, respectively. Tissue autofluorescence was induced by a blue light from an He-Cd laser coupled to the illumination channel of the bronchoscope and analyzed by a ratiofluorometer. One or more sites of moderate or severe dysplasia were found in 12% of the exsmokers and current smokers but in none of the nonsmoker volunteers. CIS was found in two of the exsmokers. The sensitivity of fluorescence bronchoscopy (86%) was found to be 50% better than that of conventional white-light bronchoscopy (52%) in detecting dysplasia and CIS. Pre- and post-bronchoscopy sputum cytology failed to detect these precancerous lesions. Our results suggest that fluorescence bronchoscopy may be an important new method that can improve the ability to detect and localize precancerous and/or CIS lesions.
A 61-year-old woman developed acute bilateral dacryocystitis secondary to Staphylococcus aureus 3 weeks after undergoing punctal occlusion with thermal cautery for keratoconjunctivitis sicca. The dacryocystitis resolved with intravenous antibiotics, aspiration of the lacrimal sacs, injection of sulfacetamide into the lacrimal sacs, and bilateral dacryocystorhinostomy. Preexisting bilateral nasolacrimal duct obstruction was postulated as the underlying cause. In these cases, irrigation of the lacrimal system is recommended before proceeding with punctal occlusion.
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A 33-year-old woman who was a chronic alcohol abuser and had bilateral visual loss was found to have megaloblastic anemia with thrombocytopenia. Both fundi showed retinal venular dilatation and tortuosity, superficial and deep intraretinal hemorrhages, white-centered retinal hemorrhages, and optic disc edema. Her megaloblastic anemia was caused by vitamin B12 and folate deficiencies, resulting from an inadequate diet and alcohol abuse. The retinal changes were believed to be the result of the severe anemia and thrombocytopenia. Both the megaloblastic anemia and retinal changes resolved promptly after she received vitamin B12 and folate supplements. This case shows that megaloblastic anemia should be suspected as a cause of bilateral retinal hemorrhages.
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In vivo autofluorescence spectra were obtained in 5 patients with carcinoma in situ, 26 patients with invasive tumors, and 1 patient with severe dysplasia. Significant spectral differences were observed between pre-cancerous, cancerous, and normal bronchial tissues. This difference may afford a method to image and/or detect early lung cancer by using tissue autofluorescence alone.
To determine why patients with allergic rhinitis alone differ in their airway response to inhaled allergen compared to patients with allergic asthma, bronchial lavage was performed in 10 subjects with allergic asthma and in five subjects with allergic rhinitis, before and after inhalation challenge with antigen to produce an immediate asthmatic reaction. Before antigen challenge, the subjects with asthma had higher absolute neutrophil counts in the lavage fluid. After antigen challenge, the subjects with asthma released significant amounts of bronchoconstrictive mediators, such as histamine and thromboxane B2 into the lavage fluid, whereas subjects with rhinitis alone did not. There was also a significant increase in prostaglandin E2 in the subjects with asthma after antigen challenge. Nonimmunologic bronchoconstriction with methacholine inhalation challenge in six other subjects with asthma did not demonstrate an increase in any of the lavage fluid mediator levels that were measured. A positive correlation was found between methacholine provocative concentration causing a 20% drop in FEV1 and the concentration of prostaglandin E2 in the lavage fluid before challenge. The significance of this observation has yet to be determined. The results suggest that subjects with allergic asthma differ from subjects with rhinitis alone in their capacity to release more mediators into the airways on antigen challenge. It is not known whether this increase in mediators is due to increase in the number of mast cells in the airways or due to increase in mediator releasability from the mast cells of subjects with asthma.
Plasma histamine and platelet-activating factor (PAF) were measured in six subjects with mild seasonal asthma before and after allergen-induced bronchoconstriction, and in six other patients with asthma before and after methacholine-induced bronchoconstriction. A significant increase in plasma histamine and PAF levels was found in patients with mild seasonal asthma after allergen-induced bronchoconstriction but not in patients with asthma after bronchoconstriction induced by methacholine. There was a significant correlation between the baseline plasma PAF levels and the degree of bronchial hyperresponsiveness to methacholine. These findings suggests that PAF may be an important mediator in the pathogenesis of asthma and bronchial hyperresponsiveness.