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Biomedical subjects

S Lam

Publications and source records attributed to S Lam.

At least 91 records · Page 5Linked to original sources
PubMed1994

Reduction of macular oedema by acetazolamide in patients with chronic iridocyclitis: a randomised prospective crossover study.

Thirty patients with cystoid macular oedema secondary to chronic iridocyclitis were enrolled in a two period, prospective, randomised, double masked, crossover study that compared sustained release acetazolamide (500 mg twice a day) with a placebo to measure the effects on the reduction of cystoid macular oedema and improvement of visual acuity. All patients were treated for 1 month with either acetazolamide or placebo, received no treatment for 1 month, and were then treated for 1 month with the other medication. Statistically significant improvement in visual acuity was seen at 14 and 28 days in the treated patients. No improvement was seen when patients received placebo. Improved visual acuity was not associated with race or sex. However, younger patients (under age 55 years) were more likely to benefit from treatment. Results of vitreous fluorophotometry, obtained at baseline and 4 weeks, demonstrated an improvement in posterior vitreous penetration ratios and mid vitreous penetration ratios after treatment with acetazolamide but not with placebo.

Acetazolamide↗
PubMed1994

Persistent asthma after repeated exposure to high concentrations of gases in pulpmills.

This is a clinicopathologic study of three subjects with irritant-induced asthma. They were pulpmill workers who had a history of multiple "gassing" episodes that occurred over a period of years. Persistent symptoms of asthma and nonspecific bronchial hyperresponsiveness and/or variable airflow obstruction occurred after at least one episode of "gassing," resulting in symptoms severe enough to require emergency room treatment. One of the three subjects had normal spirometry values before he entered the pulpmill. Bronchial biopsy done on these subjects showed changes compatible with asthma, including thickened basement membrane in two and cellular infiltration with activated eosinophils and mononuclear cells in all three. The results of immunohistology of bronchial mucosal biopsy of these subjects were compared with those of patients with allergic asthma and patients with Western red cedar-induced asthma. Subjects with irritant-induced asthma had a greater density of activated eosinophils and fewer T-lymphocytes, suggesting that cell-mediated immune mechanisms are not involved in the pathogenesis of this condition.

Adult↗
PubMed1994

Photodynamic therapy of lung cancer.

Photodynamic therapy (PDT) has been used investigationally for the treatment of lung cancer since 1980. Following systemic administration of a photosensitizing agent such as porfimer sodium (Photofrin; manufactured by Lederle Parenterals, Carolina, Puerto Rico, under license from Quadra Logic Technologies, Inc, Vancouver, British Columbia, Canada), specialized optical delivery systems are engaged to deliver light of a specific wavelength (630 nm for porfimer sodium) to neoplastic tissue. A promising use of PDT appears to be treatment of early stage lung carcinoma. Phase I-II clinical trials by Hayata's group in Japan showed that for superficial early lung cancer less than 1 cm in surface diameter, complete eradication can be achieved in approximately 90% of cases. Additional phase II-III clinical trials have demonstrated an average of 90% complete response rates for superficial tumors less than 1 cm in diameter. Preoperative PDT may be useful for larger neoplasms to reduce tumor burden and potentially lessen the degree of surgery required. At the British Columbia Cancer Agency, 22 patients with 30 radiologically occult cancers were treated with PDT. In contrast to Hayata's studies, most of these patients had rather extensive tumor burden. Thirty percent of the tumors involved two or more bronchi, and more than half of them were greater than 1 cm in surface diameter. Twenty-three percent of the cases were bronchial stump recurrences. In the group of patients with bronchial stump recurrence, although a complete response was obtained with PDT initially, local recurrences occurred in 75% of cases. These results suggest that recurrent tumor in the bronchial stump should not be treated with PDT because of difficulty in delivering light endobronchially to distal tissues. Photodynamic therapy may have a role in the palliation of advanced, inoperable, obstructive bronchial tumors. Phytodynamic therapy in combination with external radiotherapy may produce better local control than external radiotherapy alone in patients with obstructive bronchial cancers. Photodynamic therapy and conventional Nd:YAG laser therapy appear to be equally effective in relieving intraluminal obstruction by tumor. An advantage of PDT for this purpose is longer time to treatment failure; a disadvantage is photosensitization that usually occurs for up to 4 weeks after treatment. In summary, PDT is a promising curative treatment for patients with small early bronchial cancers.

Airway Obstruction↗
PubMed1993

Is the use of boxed gloves in an intensive care unit safe?

PURPOSE: To identify the type, rate, burden, and pattern of contamination of boxed, clean but nonsterile gloves in our intensive care unit (ICU). MATERIALS AND METHODS: The fingertips of the first, middle, and last two pairs of gloves in 29 boxes in routine service in our ICU were cultured. The first of each of these three sets were removed aseptically, the second in a routine fashion. RESULTS: We found 16 of 29 (55%) first pairs removed aseptically to be contaminated with a mean bioburden of 1.8 colony-forming units (CFU). The percentage contamination and bioburden did not change significantly with position in the box. Use of routine compared with strict aseptic technique increased the rate of contamination by only 11% (95% confidence interval [CI] -0.05 to +0.27 percentage points) and bioburden by only a mean of 3.4 colonies per pair (CI -0.51 to +4.90 CFU). The length of the time the boxes were open and in use was unrelated to whether the final aseptically removed pair was sterile or contaminated. The predominant organisms were coagulase-negative staphylococci. CONCLUSIONS: One half the pairs of latex examination gloves in our ICU were sterile despite repeated barehanded access to the boxes. Those contaminated exhibited a small bioburden of low pathogenic potential. No pattern of contamination or unsafe duration of box use were observed. The use of boxed, clean, nonsterile gloves appears safe for routine use in an ICU.

Bacterial Infections↗
PubMed1993

Immunologic studies of the mechanisms of occupational asthma caused by western red cedar.

BACKGROUND: Occupational asthma caused by western red cedar (Thuja plicata) is a common problem in sawmill industries. The objective of this study was to examine the cellular and immunologic mechanisms of western red cedar asthma (WRCA) more closely. METHODS: Bronchial biopsy specimens, bronchoalveolar lavage (BAL) mast cells and peripheral blood basophils from patients with WRCA, patients with atopic asthma, and nonatopic control subjects were challenged in vitro with plicatic acid (PA), PA-human serum albumin conjugate (PA-HSA), grass pollen, or calcium ionophore. RESULTS: PA (100 micrograms/ml) released histamine from the basophils of 9 of 11 patients with WRCA, 1 of 7 patients with atopic asthma, and 2 of 7 normal subjects. PA triggered histamine release from 10 of 11 bronchial biopsy specimens and 8 of 8 BAL samples from patients with WRCA. Interestingly, PA released histamine from BAL cells and bronchial biopsy specimens from 3 of 7 normal subjects but in none of the patients with atopic asthma. PA-HSA-induced histamine release from basophils and biopsy specimens was confined to patients with WRCA. PA-specific IgE was not detectable in serum from most patients with WRCA, and their serum did not transfer PA sensitivity to human lung fragments or lactate-stripped basophils. After pretreatment with anti-IgE in the absence of calcium, basophils from 14 subjects with WRCA still responded to PA (mean 64% to 67% of pretreatment response), whereas responses to grass pollen or anti-IgE were abolished. CONCLUSIONS: This study confirms that PA releases histamine from bronchial mast cells of most patients with WRCA but not from those of patients with atopic asthma. The PA response of some normal subjects suggests that PA may have both specific and nonspecific actions on mast cells and basophils, whereas the serologic studies indicate histamine release in WRCA cannot simply be attributed to PA-specific IgE.

Adult↗
PubMed1993

Occupational asthma in a technologist exposed to glutaraldehyde.

BACKGROUND: Occupational asthma can be caused by several sterilizing agents, including glutaraldehyde, which has been shown to cause irritation of the eyes and upper respiratory tract and skin rash. We report a case of occupational asthma that was caused by exposure to glutaraldehyde. METHODS: To document the diagnosis of occupational asthma in a respiratory technologist, the following tests were performed: preshift and postshift spirometry, serial measurements of peak expiratory flow rate and nonspecific bronchial hyperresponsiveness, and workplace challenge test. RESULTS: Monitoring of peak expiratory flow rate showed improvement when the subject was away from the workplace. Improvements in forced expiratory volume in 1 second (FEV1) and provocative concentration causing a 20% fall in FEV1 were also observed. A workplace challenge test showed a progressive fall in FEV1 when the subject was exposed to glutaraldehyde in a sterilizing agent used to clean bronchoscopes at her workplace. After the diagnosis of occupational asthma was confirmed, the subject continued to assist with bronchoscopy but no longer cleaned the bronchoscopes. CONCLUSIONS: This case study illustrates the usefulness of a workplace challenge test in confirming the diagnosis of occupational asthma. It also indicates the importance of preventing or reducing exposure to sterilizing agents such as glutaraldehyde by means of effective ventilation and proper storage and enclosure during use.

Adult↗
PubMed1993

Ocular aspergillosis isolated in the anterior chamber.

BACKGROUND: In all cases in which ocular involvement has been reported in endogenous aspergillosis, the posterior segment of the eye was involved. METHODS: The authors examined a patient who had been intubated and treated with corticosteroid therapy for status asthmaticus and in whom a mass later developed in the anterior chamber of the right eye. RESULTS: Computed tomography showed a solitary lesion in the left lower pulmonary lobe and multiple brain lesions that enhanced with contrast. Aspergillus fumigatus was cultured from the endotracheal tube. However, ocular and blood cultures were negative, as were the results of a bone marrow biopsy, lung biopsy, and anterior chamber paracentesis. Disseminated aspergillosis was confirmed when a biopsy of the anterior chamber mass was performed, and results of histopathologic examination showed the presence of hyphae. The patient responded to a regimen of antifungal drugs. CONCLUSION: This is the first known reported case in which the diagnosis of disseminated aspergillosis was confirmed with biopsy of an anterior chamber mass. This case demonstrates that Aspergillus organisms may disseminate to the anterior chamber of the eye without involving the posterior segment.

Adult↗
PubMed1993

Preclinical trial of 4-aminopyridine in patients with chronic spinal cord injury.

4-Aminopyridine (4-AP) is a K+ channel blocking agent that enhances nerve conduction through areas of demyelination by prolonging the duration of the action potential and increasing the safety factor for conduction. We have investigated the effects of 4-AP (24 mg total dose-intravenous) in 6 patients with spinal cord injury (3 complete, 3 incomplete) with the intent of overcoming central conduction block, or slowing, due to demyelination. Vital signs remained stable and only mild side effects were noted. The 3 patients with incomplete injuries all demonstrated enhanced volitional EMG interference patterns and one patient exhibited restored toe movements. The changes were reversed on drug washout. There were no changes in segmental reflex activities. These results are consistent with those obtained from 4-AP trials with animal models of spinal cord injury, showing modest therapeutic benefit attributable to enhanced central conduction.

4-Aminopyridine↗
PubMed1993

Primary actinomycotic endocarditis: case report and review.

Endocarditis due to Actinomyces species for which a portal of entry cannot be identified is extremely rare. We present a case of primary endocarditis due to Actinomyces israelii with an unknown portal of entry and review seven similar cases reported in the literature since 1939. The disease predominantly affects males. Clinical features are similar to those of bacterial endocarditis due to other organisms. Penicillin remains the drug of choice for treatment of this condition. The optimal duration of treatment has not yet been determined; however, with early diagnosis and appropriate antimicrobial therapy, the prognosis is good.

Actinomyces↗
PubMed1993

Enterococcal infectious crystalline keratopathy.

Two patients developed infectious crystalline keratopathy (ICK) 9 and 11 months after penetrating keratoplasty. In both cases, cultures yielded enterococcus sensitive to vancomycin. The first patient developed diffuse loss of corneal and conjunctival epithelia after 24 h of treatment with vancomycin eyedrops, whereas the second patient did not respond after 14 days of topical vancomycin therapy. Both patients eventually required penetrating keratoplasty. Enterococcus is a ubiquitous bacterium resistant to many antibiotics that should be suspected of causing ICK.

Aged↗
PubMed1993

Topical cyclosporin A in the treatment of anterior segment inflammatory disease.

Topical cyclosporin A was used in the management of 43 patients with a variety of anterior segment inflammatory disorders that had failed corticosteroid treatment. Treatment with topical cyclosporin A ranged from 1 week to 43 months, with a mean treatment period of 13 months. Thirty-five patients (81%) with disorders including high-risk keratoplasty, atopic and vernal keratoconjunctivitis, ligneous conjunctivitis, ulcerative keratitis, and Mooren's ulcer had a beneficial result, with resolution, reduction, or prevention of inflammation. Six patients (14%) with scleritis, ocular cicatricial pemphigoid, or endothelitis showed no clinical improvement. Two patients (5%) had significant ocular discomfort, and the drug had to be discontinued in them. None of the other patients developed local side effects. Twenty-seven of these patients were followed with serial cyclosporin A blood levels and serum creatinine. None of these patients developed measurable drug blood levels or renal toxicity.

Administration, Topical↗
PubMed1993

Elevated serum sialic acid in idiopathic acute iridocyclitis.

We measured the serum levels of sialic acid in 12 patients with idiopathic acute iridocyclitis and 18 normal controls. Sialic acid levels were significantly elevated in the patients with idiopathic acute iridocyclitis. Since animal studies have shown that intraocular inflammation alone cannot elevate serum level of sialic acid, the result of our study suggest that idiopathic acute iridocyclitis may be a multiorgan disease with systemic effects.

Acute Disease↗
PubMed1993

Iris crystals in chronic iridocyclitis.

Iris crystals in three patients with idiopathic iridocyclitis, Fuchs' heterochromic iridocyclitis, and iridocyclitis associated with systemic pseudolymphoma are described. Two patients had iris crystals in one eye, and the other patient had bilateral involvement. The number of iris crystals in each eye ranged from one to multiple crystals. Iris crystals were minute and refractile and glistened with light; they have previously been reported to be Russell bodies and to be associated with hypergammaglobulinaemia. However, two of the patients, who underwent serum protein electrophoresis, did not demonstrate hypergammaglobulinaemia.

Adult↗
PubMed1993

Detection and localization of early lung cancer by imaging techniques.

Two new technologic developments may have a significant impact on the detection and localization of early lung cancer. These two developments work together in a complementary way. The first is a solid-state microscope that can be applied in the prescreening of sputum cytology specimens. The finding that malignancy-associated changes (MACs) are present in ostensibly normal bronchial epithelial cells may be used to improve the sensitivity of sputum cytology to detect cancer. Once abnormal or MAC cells are found, a second device, a fluorescence bronchoscope, can be employed to localize the source of the abnormal cells. Fluorescence bronchoscopy is also a potentially useful tool for procuring premalignant tissue for molecular biology studies and for monitoring the progress of patients in chemoprevention studies.

Bronchoscopy↗
PubMed1993

Detection and sequencing of p53 gene mutations in bronchial biopsy samples in patients with lung cancer.

We demonstrated the feasibility of detection of p53 gene mutations in bronchial biopsy samples from patients with lung cancer. Following DNA extraction from two to three pieces of bronchial tissue obtained by fiberoptic bronchoscopy, p53 gene mutations were screened using polymerase chain reaction/single-strand conformation polymorphism technique. We examined four bronchial biopsy specimens from patients with squamous cell carcinoma of the lung and detected one point mutation at codon 130 (C to G, Leu to Val). This technique will be very useful for studies on early detection of lung cancers or for an analysis of a suspected premalignant lesion. Furthermore, this technique enables us to know the status of oncogene or tumor suppressor gene at the time of diagnosis, which may be very useful for a treatment of patients with cancer in the not too distant future.

Aged↗
PubMed1993

Preliminary study of a new intraocular method in the diagnosis and treatment of Propionibacterium acnes endophthalmitis following cataract extraction.

Late endophthalmitis, due to Propionibacterium acnes, developed in three patients following uncomplicated extracapsular cataract extraction and posterior chamber intraocular lens (PC-IOL) insertion. Cultures from the capsular bag yielded P. acnes in all three. With topical anesthesia and through an anterior chamber paracentesis, culture specimens were taken from and clindamycin irrigated into the capsular bag. Filtered 100% oxygen was introduced into the anterior chamber in two; the third also received an injection of gentamicin and dexamethasone into the capsular bag. After treatment, two patients received oral antibiotics; one received hyperbaric oxygen therapy. Visual acuity was improved and inflammation reduced in all three. However, after treatment, ocular toxic effects due to clindamycin were suspected in one. This approach offers several clear advantages, including topical anesthesia, outpatient management, elimination of the need for vitrectomy, and retention of the intraocular lens (IOL).

Aged↗
PubMed1993

Iris cavernous hemangioma in a patient with recurrent hyphema.

A 41-year-old woman presented with a hyphema in her right eye. Clinical examination revealed a vascular lesion of the iris that had enlarged over a 6-month period. The patient had no other evidence of ocular or cutaneous vascular malformations. Subsequently she experienced recurrent episodes of spontaneous hyphema, and there was objective evidence of growth of the lesion. Consequently, the lesion was excised by means of a sector iridectomy. Histopathological examination showed several large vascular compartments separated by thin, fibrous septa and lined by endothelium, consistent with a cavernous hemangioma. A benign iris melanocytic lesion was identified adjacent to the cavernous hemangioma. The intraocular pressure in the affected eye remained normal after the lesion was removed. After 6 months of follow-up no new hyphemas had developed. Iris cavernous hemangioma should be added to the differential diagnosis of recurrent hyphema.

Adult↗