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Biomedical subjects

I McLean

Publications and source records attributed to I McLean.

At least 19 recordsLinked to original sources
PubMed1995

Development of multiple-antibiotic-resistant (Mar) mutants of Pseudomonas aeruginosa after serial exposure to fluoroquinolones.

Laboratory-derived fluoroquinolone-resistant mutants were created by serially passaging wild-type Pseudomonas aeruginosa on fluoroquinolone-containing agar to obtain high-level fluoroquinolone resistance (e.g., ciprofloxacin MIC of 1,024 micrograms/ml). With increases of 4- to 32-fold in MICs of fluoroquinolones, these organisms demonstrated (relative to wild-type) normal morphology, resistance to fluoroquinolones only, no change in fluoroquinolone uptake, and no change in lipopolysaccharide profiles or outer membrane protein profiles. Complementation with wild-type Escherichia coli gyrA restored fluoroquinolone susceptibility, suggesting that these were gyrA mutants. After 4- to 32-fold increases in fluoroquinolone MICs (with continued passage on fluoroquinolone-containing agar) isolates demonstrated altered morphology, a multiple-antibiotic-resistant (Mar) phenotype (including cross-resistance to beta-lactams, chloramphenicol, and tetracycline), reduced fluoroquinolone uptake and altered outer membrane proteins (reductions in the 25- and 38-kDa bands as well as several bands in the 43- to 66-kDa region). Complementation with wild-type E. coli gyrA partially reduced the level of fluoroquinolone resistance by approximately 8- to 32-fold, suggesting that these mutants displayed both gyrA and non-gyrA mutations.

Anti-Infective Agents↗
PubMed1995

Actinic keratosis and dysplasia of the conjunctiva: a clinicopathological study of 45 cases.

OBJECTIVE: To characterize precancerous conjunctival intraepithelial tumours on file at the Armed Forces Institute of Pathology (AFIP). DESIGN: Chart review. SETTING: Registry of Ophthalmic Pathology of the AFIP. NUMBERS: Forty-five patients with intraepithelial neoplastic lesions of the conjunctiva followed for at least 2 years. MAIN OUTCOME MEASURES: Extent; papillomatous pattern; degree of parakeratosis, hyperkeratosis and atypia; and amount of solar elastosis. RESULTS: Based on their histologic appearance, 24 cases were classified as actinic keratosis and 21 cases as dysplasia. Clinically, lesions classified as actinic keratosis tended to be focal and leukoplakic, whereas those classified as dysplasia tended to be diffuse and gelatinous. Two of the lesions classified as actinic keratosis recurred, compared with 13 of the lesions classified as dysplasia. In one patient with dysplasia locally invasive squamous cell carcinoma developed after numerous recurrences, requiring orbital exenteration. The degree of atypia was not correlated with recurrence in either group. CONCLUSIONS: Most intraepithelial neoplastic lesions of the conjunctiva can be readily diagnosed by the ophthalmic pathologist as either actinic keratosis or dysplasia.

Carcinoma in Situ↗
PubMed1994

A comparison of radiographic signs of degeneration to corresponding MRI signal intensities in the lumbar spine.

OBJECTIVES: To evaluate plain film radiographic findings of lumbar intervertebral disk degeneration. DESIGN: A cross-sectional observational design was employed. Contingency tables were constructed to evaluate the relationships between radiographic findings of degeneration and the corresponding MRI signal intensities of the inner intervertebral disk. SETTING: Twenty-four consecutive cases were retrospectively selected from an MRI imaging center. PATIENTS: No exclusion was made on the basis of age or sex. MAIN OUTCOME MEASURES: Radiographic findings of IVD degeneration include: Narrowed disk space, osteophyte formation, end-plate sclerosis, vacuum phenomenon, end-plate irregularity and Schmorl's node formation. The inner IVD signal intensity of the sagittal T2-weighted MRI image was visually categorized by three radiologists. The signal intensities were divided into low, medium and high categories. MAIN RESULTS: Visually reduced disk height, osteophytes and eburnation all demonstrate significant relationships with MRI signal intensity. Due to their infrequency, no significant relationships could be found with vacuum phenomena, end-plate irregularity, and Schmorl's nodes when compared to MRI signal intensity. CONCLUSIONS: In conclusion, visually reduced disk height is frequently associated with decreased signal intensity and, therefore, significantly indicates internal disk derangement. Osteophytes are more commonly present when the signal intensity is low. However, high signal intensity is associated with osteophytic change as well. Therefore, osteophytic change is less sensitive and accurate to early inner disk degenerative change. When osteophytes and reduced disk height are present together, a stronger prediction of degeneration is possible then when either finding is present alone. Due to their infrequency, eburnation, vacuum phenomena, end-plate irregularity and Schmorl's nodes are less helpful indicators of degeneration.

Adult↗
PubMed1993

Immunohistochemical analysis of lattice corneal dystrophies types I and II.

Corneal buttons from four patients with lattice corneal dystrophy (LD) type I, thought to be an isolated corneal amyloidosis, and from six patients with LD type II, part of systemic familial amyloidosis, Finnish type (FAF; Meretoja's syndrome), were studied by immunohistochemistry to determine the differential distribution in the amyloid deposits of amyloid P component (AP), mutated gelsolin specific for FAF, and native gelsolin. In both types of LD, antibodies to AP labelled lattice lines and a discontinuous layer of amyloid deposits under Bowman's layer. In LD type II, particularly, they also reacted with streak-like amyloid deposits between corneal almellae, especially in the limbal region. While the anti-FAF antiserum strongly labelled all amyloid deposits in LD type II, it failed to react unequivocally with them in LD type I. Both in LD type I and in two control specimens representing granular dystrophy, the monoclonal antibody (MAb) GS-2C4 to gelsolin faintly labelled some deposits, while in LD type II it reacted non-homogeneously with most amyloid deposits. In all specimens, MAb GS-2C4 labelled corneal epithelial cells and occasional stromal keratocytes and endothelial cells. The results suggest that Meretoja's syndrome, a systemic disease, can be diagnosed even retrospectively from corneal buttons subjected to histopathological study.

Adult↗
PubMed1991

A simple, efficient, and reproducible method for estimating the malignant potential of uveal melanoma from routine H & E slides.

The malignant potential of 100 intraocular melanomas was assessed by determining the mean of the ten largest nucleoli (MTLN) using a modification of previously described techniques. For each microslide, a five millimeter path through the central portion of the tumor was traversed on a manually controlled mechanical stage. Selected nucleoli in this area were measured at 2000x power using a digital filar micrometer. In their reproducibility and correlation with malignant potential, these measurements proved comparable to standard deviation of nucleolar area (SDNA), which has been well documented as an objective histologic predictor of mortality from intraocular melanoma. This new method for measuring MTLN requires less than 11 minutes per case, compared to an average of 28 minutes for the original method. The measurements of SDNA required approximately 40 minutes per case and a much more elaborate system than that needed for MTLN.

Cell Nucleolus↗
PubMed1989

A simple cytologic method for predicting the malignant potential of intraocular melanoma.

The malignant potential of 100 intraocular uveal melanomas was assessed by determining the mean of the ten largest nucleoli (MTLN). On a single standard microslide from each tumor, the maximum diameter of the ten largest nucleoli was measured using a manually operated micrometer. For comparison, three additional histopathologic parameters were determined for each case: Standard deviation of nucleolar area (SDNA), Callender cell type (CT), and largest tumor dimension (LTD). Of these four parameters, MTLN and SDNA were most highly correlated with death from ocular tumor. Furthermore, repeat measurement of all 100 cases revealed a level of reproducibility for MTLN similar to that for SDNA. Of greatest importance, the micrometer technique employed in this study has substantial cost and labor advantage over the computer-controlled system required to measure SDNA.

Cell Nucleolus↗
PubMed1986

Netball injury.

Explore the source record for details and available documents.

Adult↗
PubMed1985

Objective assessment of the malignant potential of intraocular melanomas with standard microslides stained with hematoxylin-eosin.

A method for extracting prognostic information from the cytologic details of intraocular melanomas was developed. With computer assistance, a technician measures the nucleolar area of 200 tumor cells randomly selected from a standard paraffin-embedded microsection stained with hematoxylin-eosin, a procedure that requires approximately 40 minutes with an apparatus that costs less than +30,000. Standard deviation of nucleolar area (SDNA), computed from these measurements, provides an objective assessment of nucleolar pleomorphism. Previous studies showed that second measurements of the same microsection or of the same tumor at different levels yield SDNA values that closely approximate the original measurements. The application of this method to 540 cases from three independent laboratories yielded a correlation of SDNA with death from tumor that was high (P much less than 0.001) and consistent among cases from all three sources. Thus, SDNA provides a clinically useful cytologic measure of the malignancy of intraocular melanomas and may ultimately prove valuable in the assessment of other types of tumors.

Cell Nucleolus↗
PubMed1984

The persisting pseudomelanoma problem.

We reviewed 6,169 cases in which whole eyes were submitted to the Armed Forces Institute of Pathology (AFIP), Washington, DC, between January 1970 and December 1980. We sought to determine whether there had been any change in the frequency of incorrect diagnoses of malignant melanoma since two previous studies had been conducted at the AFIP. Of 744 eyes with clear media submitted with the clinical diagnosis of malignant melanoma, the rate of incorrect diagnosis was 6.4% (48 of 744 cases). During the 11-year study, the rate of incorrect diagnoses declined from 12.5% to 1.4%. Despite that overall decrease, the locations and frequency of simulating lesions were comparable with those found in the two previous studies. We believe our current findings reflect a significant increase in diagnostic accuracy among clinicians practicing outside of major academic centers.

Choroid Neoplasms↗
PubMed1984

Flurbiprofen interaction with single doses of atenolol and propranolol.

In patients with mild hypertension, flurbiprofen in a dose of 100 mg daily for 7 days attenuated the hypotensive effect of a single dose of propranolol 80 mg but not of atenolol 100 mg. The attenuation was not due to an effect on the pharmacokinetic profile of either propranolol or atenolol. An alternative explanation is required.

Adult↗
PubMed1984

Assessment of the acute knee injury.

Knee injuries are the main reason for premature retirement from contact and rotational sports in the young healthy individual. They cause significant interference with employment, particularly tradesmen or persons with labouring jobs. These injuries may cause persisting disability and predisposition to early degenerative changes, if not recognised and appropriate treatment commenced early.

Humans↗
PubMed1981

Redox potential and survival of virulent Treponema pallidum under microaerophilic conditions.

A strongly reduced culture medium, capable of maintaining the virulence of Treponema pallidum (Nichols) for several days, was exposed to an atmosphere of 3% oxygen in nitrogen for 2-3 days before inoculation with T pallidum. By using various volumes of medium in uniform tubes a range of redox potentials (Ecal) from -94 mV to -325 mV was produced depending on the surface area-to-volume ratios of the medium. The anaerobic medium had an Ecal value of -387 mV. The medium was inoculated with T pallidum and incubated in an atmosphere of 3% oxygen. The survival of treponemes at different redox potentials was monitored by observing the retention of motility and by measuring the latent period of infection after inoculation of the cultures into the shaved backs of rabbits. Under these conditions T pallidum survived longest at low (electronegative) redox potential. An inverse linear relationship was observed between the redox potential of the culture medium and the survival of T pallidum, as measured by the time required for a 90% reduction of virulent organisms. No optimum redox potential was detected, the most electronegative medium (-325 mV, Ecal) giving the best survival.

Bacteriological Techniques↗
PubMed1979

Clinicopathologic characteristics of orbital lymphoid hyperplasia.

The clinical characteristics and microscopic features of the biopsy specimens of 66 patients with orbital lymphoid tumors were analyzed with respect to clinical outcome (disease remaining localized to the orbit or developing associated extraorbital lesions). The patients' average age was 63 years, and their tumors had a marked tendency to arise in the anterosuperior orbit. No clinical or radiographic findings helped to distinguish the cases of localized disease from disseminated disease. The lesions were divided microscopically into three categories: reactive lymphoid hyperplasia (16), atypical lymphoid hyperplasia (38), and malignant lymphoma (12). Extraorbital lesions developed in 25%, 50%, and 75% of cases, respectively. The five-year mortality rates were also significantly different for each type of lesion: 6%, 19%, and 58%, respectively.

Adult↗