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Biomedical subjects

M R Wilson

Publications and source records attributed to M R Wilson.

At least 145 records · Page 8Linked to original sources
PubMed1991

The ocular effects of gases when injected into the anterior chamber of rabbit eyes.

We studied the toxic effects of sulfur hexafluoride and perfluoropropane in comparison with air, balanced salt solution, hyaluronate sodium, and aqueous humor in a rabbit model. Sixty normal pigmented rabbits were studied during a period of 4 weeks. The variables studied were slit-lamp biomicroscopic examination of the anterior segment, intraocular pressure as measured by pneumotonometry, corneal thickness and endothelial cell count as measured by specular microscopy, lens opacity by Scheimpflug photography, and light and transmission electron microscopy. All three gases were more toxic to the cornea and lens than were balanced salt solution, hyaluronate, and aqueous humor. However, 15% perfluoropropane and 50% sulfur hexafluoride were no more toxic to the eye than air was. Therefore, this study suggests that nonexpansile mixtures of perfluoropropane and sulfur hexafluoride may be beneficial and relatively safe in re-forming persistently flat anterior chambers in situations where the use of air is being considered.

Air↗
PubMed1991

Immunofluorescent labeling using covalently linked anti-phycoerythrin antibodies and phycoerythrin polymers.

We have developed methods for covalently attaching anti-phycoerythrin (PE) MAbs to other antibodies, and for using PE or polymers of PE in conjunction with these conjugates to rapidly produce specific, high intensity fluorescent labeling of antigens. The performance of these systems was examined on the surface of microspheres and on the cell surface. The noncovalent means by which PE is incorporated into the label complex in this method makes it possible to use crude algal homogenate successfully as a source of PE in immunofluorescence assays. The intensity of labeling achieved using this method is comparable to, or in some cases better than, that obtained using a direct PE conjugate. With the aim of amplifying the intensity of fluorescence obtained, we produced two types of covalently linked complexes. These were an anti-PE MAb, designated PE6, linked to itself (i.e., PE6-PE6), and PE linked to itself (i.e., PE-PE). When used in a two-stage procedure in place of monomeric PE alone, these complexes increased the intensity of fluorescence obtained on the surface of microspheres by more than fourfold. On the cell surface, the performance of this system varied from one antigen to the next but in most cases was restricted to, at best, a 60% increase in the intensity of fluorescence and in many cases only about a 30% increase.

Antibodies, Monoclonal↗
PubMed1991

Purification and characterization of infectious Marek's disease virus genomes using pulsed field electrophoresis.

Marek's disease virus (MDV) is an acutely oncogenic avian herpesvirus. The tightly cell-associated in vitro growth characteristics of MDV present unique problems when attempting to purify, analyze, and manipulate MDV genomes. To facilitate molecular characterization of MDV, contour-clamped homogeneous electric fields electrophoresis (CHEF) was used to purify infectious MDV genomes. CHEF techniques were optimized for evaluation of total genome size and alterations in structure which occur during in vitro attenuation of oncogenic MDV. Our results indicated that genomes of attenuated serotype 1 MDV strain JM may contain deletions totaling 15 kbp while high-passage serotype 2 nononcogenic MDV strains SB-1 and 281MI/1 were 5 and 3 kbp larger, respectively, than their low-passage counterparts. Using cell-free CHEF-purified MDV genomes as hybridization probes, we identified a 200-bp deletion in attenuated genomes of the very virulent MDV strain MD11. At present, it is unclear if this 200-bp is related to mutations which lead to loss of oncogenicity or pathogenicity in MD11. This study is the first report which describes procedures for purification of infectious herpesvirus genomes from pulsed-field gels. Our results demonstrate that pulsed-field-purified viral DNA will facilitate molecular characterization of MDV and other cell-associated herpesviruses.

Animals↗
PubMed1991

Use of bioerodible polymers impregnated with mitomycin in glaucoma filtration surgery in rabbits.

A prospective, randomized, double-masked, and placebo-controlled study was performed to evaluate the effects of a localized and sustained release of mitomycin on the success of glaucoma filtration surgery in rabbits. A bioerodible polymer was used as the drug carrier. Full-thickness filtration surgeries were performed and data from 22 rabbits were collected. One eye received a polymer impregnated with mitomycin (0.02 mg or 0.06 mg), while the fellow eye received a drug-free polymer. Intraocular pressure, bleb survival, and postoperative complications were investigated. Intraocular pressures remained lower for a longer period of time (P less than 0.004) and filtration blebs lasted longer (P less than 0.05) in experimental eyes than in control eyes. Conjunctivitis and sectorial corneal haze occurred more frequently in eyes treated with the higher dosage mitomycin compared with control eyes. The use of mitomycin-C in a polymer delivery system appeared to promote the success of glaucoma filtration surgery in rabbits. With the lower dosage of mitomycin, clinically significant ocular toxicity was not noted.

Animals↗
PubMed1991

The effects of topical mitomycin on glaucoma filtration surgery in rabbits.

A prospective, randomized, double-masked, and placebo controlled study was performed to examine the effects of topically applied mitomycin on the success of full thickness filtration surgery in 23 rabbits. Both eyes of each rabbit had surgery by the same surgeon. After surgery, the experimental eye received a single subconjunctival injection of mitomycin (0.2 mg), and 50 microliters of a 0.2 mg/cc solution of mitomycin topically four time daily. The fellow control eyes were treated with sterile water. The mean intraocular pressure reduction from baseline exhibited by the experimental eyes was greater than that observed for the control eyes. The difference in intraocular pressure reduction between the two groups was statistically significant from post-operative day three through day 21 (p less than .05). With survival analysis, fewer failures were noted in the experimental eyes compared to control eyes for each time period throughout the study (p less than .005). The experimental eyes also demonstrated a longer time to bleb failure although this difference did not achieve statistical significance (p less than .10). An additional five rabbits were treated with the experimental drop in one eye and sterile water in the fellow eye but underwent no surgery. No differences between eyes were noted with regard to intraocular pressure change or anterior segment pathology. These data demonstrated the efficacy of mitomycin in promoting filtration surgical success in rabbits.

Administration, Topical↗
PubMed1991

Frequency and characteristics of ocular trauma in an urban population.

All patients presenting with ocular trauma to the emergency room of a large inner-city hospital during a 2-month period were prospectively examined and interviewed. Of 3,627 trauma visits, ocular trauma accounted for 126 (3%). There were 514 trauma admissions; 26 (5%) of these were for ocular trauma. Bilateral injuries were encountered in 35 (27.6%) of the 126 patients. Patients in early adulthood (18 to 30 years) sustained the most eye injuries (36.9%) whereas elderly people had the fewest (1.6%). Males sustained ocular injuries more frequently than females (3.5:1) and blacks more frequently than Hispanics (2.4:1). Assault was predominantly the most common circumstance of injury (51.2%). Alcohol or drug use (26.7%) and belonging to a gang (6.2%) were other factors found to be uniquely related to ocular injury in this particular socioeconomic environment.

Adolescent↗
PubMed1990

The immunoglobulin M heavy chain constant region gene of the channel catfish, Ictalurus punctatus: an unusual mRNA splice pattern produces the membrane form of the molecule.

The immunoglobulin (IgM) heavy chain constant region gene of the channel catfish, Ictalurus punctatus, has been cloned and characterized. The gene contains four constant region domain-encoding exons (CH1 to CH4) expressed in the secreted form of the immunoglobulin, and two exons encoding the transmembrane (TM) domain utilized in the lymphocyte membrane receptor form of the immunoglobulin. The sequence of a cDNA clone encoding the 3' region of the message for the membrane receptor form of the mu chain indicates that the TM1 exon is spliced directly to the CH3 exon, and not into a site within the CH4 exon, as occurs in the mammals, a shark and an amphibian. This unusual pattern of splicing, which produces a membrane heavy chain that is characteristically smaller than the secreted heavy chain, may be common to all teleost fish.

Amino Acid Sequence↗
PubMed1990

Characterization of the gene encoding herpesvirus of turkeys gp57-65: comparison to Marek's disease virus gp57-65 and herpes simplex virus glycoprotein C.

A gene encoding herpesvirus of turkeys (HVT) strain FC 126 gp57-65 has been mapped to the viral genome and sequenced. The HVT (FC 126) gp57-65 gene maps to BamHI fragments K1 and M, colinear with the gene from Marek's disease virus (MDV) strain GA. HVT gp57-65 gene sequences were compared to the MDV strain GA gp57-65 gene that we sequenced previously. Overall, the two sequences are 66% identical, with greater similarity in the 3' proximal two thirds of the genes. HVT gp57-65 gene sequences have a slightly higher overall guanosine plus cytosine (G + C) content than MDV gp57-65 gene sequences (46% vs. 41%, respectively). A single, long open reading frame capable of encoding 523 amino acids was identified within the HVT gp57-65 gene region. The predicted precursor polypeptide derived from this open reading frame would have a calculated molecular weight of 58,587. The predicted HVT gp57-65 amino acid sequences contain six potential N-linked glycosylation sites (asn-x-ser/thr). Five of these six potential N-linked glycosylation sites are conserved between the HVT and MDV predicted amino acid sequences. Hydropathic analysis of the predicted HVT gp57-65 amino acid sequences indicate the presence of an amino-terminal hydrophobic sequence, which may function as a signal peptide, and a hydrophobic carboxyl terminal sequence, which may function as a membrane anchor sequence. Overall, MDV gp57-65 and HVT gp57-65 precursor polypeptide sequences are 73% homologous and share many potential antigenic epitopes. Predicted MDV and HVT gp57-65 protein sequences are similar to those of herpes simplex virus glycoprotein C (gC) and gC-like proteins from other herpes-viruses. Similarities are scattered throughout the molecule, with a primary concentration near the carboxyl half of the molecule. One stretch of 60 amino acids (HVT amino acids 378-437 and MDV amino acids 350-410) are relatively well conserved among gC-like proteins from six herpesviruses. The possible implications of these homologies and the potential roles of gC-like proteins in virus infection, growth, and replication are discussed.

Amino Acid Sequence↗
PubMed1990

Fertility of sows mated on different days of the week.

The farrowing rates resulting from matings on different days of the week were determined for a 2800-sow intensive piggery in both 1983 and 1984. The results showed that sows mated early in the week achieved a significantly higher farrowing rate than sows mated late in the week (P less than 0.0001). During the seasonal (summer to autumn) infertility period, Wednesday matings resulted in a poor farrowing rate whereas for the rest of the year farrowing rates following Wednesday matings were similar to those for Sunday Monday and Tuesday matings. Consistent results were obtained for data from both years. It is proposed that the stress of regrouping unmated sows on Wednesday to accommodate newly weaned sows is responsible for this decrease in fertility. This study illustrates how detailed analysis of farrowing rates on a day of mating basis can identify a problem which is otherwise masked by weekly data.

Animals↗
PubMed1990

Long-term follow-up study of mitomycin eye drops as adjunctive treatment of pterygia and its comparison with conjunctival autograft transplantation.

We observed 48 patients for 7-21 months (mean, 18 months) after pterygium excision and 2 weeks of placebo or mitomycin topical therapy to evaluate whether or not the short-term efficacy of mitomycin in preventing pterygium recurrence would be reflected in long-lasting efficacy as well. Placebo-treated pterygia showed a 73% recurrence rate. One of 58 (1.7%) mitomycin-treated pterygia recurred (p less than 0.05). We also performed a pilot study comparing pterygia treated with excision followed by 0.4 mg/ml of mitomycin to pterygia treated with excision coupled with conjunctival autograft transplantation to estimate the number of patients required for a randomized clinical trial comparing these two treatment modalities and thereby to decide whether or not such a study would be justified. Thirteen primary and two recurrent pterygia were treated with mitomycin, while 14 primary and one recurrent pterygia were treated with conjunctival autograft transplantation. With mean follow-up times of 4 and 6 months, respectively, no recurrences were noted in the mitomycin-treated group, while the conjunctival autograft transplantation group had one recurrence (6.6%). We estimate that 400 patients would be required for a properly designed clinical trial comparing these two effective therapies for prevention of recurrent pterygia. We conclude that such a study is unjustified, and further conclude that the vastly less expensive, simple therapy of mitomycin eye drops is the more appropriate treatment.

Administration, Topical↗
PubMed1989

Posterior lip sclerectomy vs trabeculectomy in West Indian blacks.

Surgical treatment in a West Indian black population with primary open angle glaucoma was randomized to full-thickness posterior lip sclerectomies or partial-thickness trabeculectomies. Forty-five posterior lip sclerectomies and 35 trabeculectomies were performed. With a mean follow-up period of 28.3 months, the eyes with posterior lip sclerectomies had lower intraocular pressures, reduced glaucoma medication requirements, and less failures. Decline of visual acuity did not differ significantly between the two groups, but early visual acuity loss due to accelerated cataract formation was noted more frequently with posterior lip sclerectomies. The incidence of flat anterior chambers also did not differ significantly, but shallow anterior chambers were more frequent and persisted for a longer time with posterior lip sclerectomies. Other complications were more frequent with posterior lip sclerectomies.

Adult↗
PubMed1989

The effect of circulating antigen on radioimmunodetection and monoclonal antibody localisation: studies in a normal rat model.

The effect of circulating antigen (human kappa light chains (LC] on radioimmunoscintigraphy was examined in a normal rat model. Rats were implanted subcutaneously with kappa (test) and lambda (control) LC coupled to sepharose beads (500 micrograms LC/ml swollen gel). When 131I-labelled monoclonal antibody, K-1-21 was injected, clear images of specific antibody localisation to the kappa implant were seen 6 days later. The kappa implant: blood ratio (K:B) was 7.69 +/- 0.45, which represented an implant uptake of 2.52 +/- 0.20 percent injected dose per gram (%ID/g). When 131I-K-1-21 was preincubated with 125I-kappa LC at ratios of up to 1:10 antibody: antigen, (w/w) before injection; or if antigen was given daily by bolus injection or continuously infused via an osmotic pump, very clear specific images of antibody localisation to the kappa implant were still obtained. There was, however, a decline in the absolute uptake of label by the kappa implant. The greatest change was observed following continuous antigen infusion, when kappa implant uptake fell to 1.26 +/- 0.1 %ID/g. Nevertheless, the K:B ratio was still maintained at 6.8 +/- 0.2, due to increased clearance of antibody from the blood. Thus, in this case, where antigen and antibody might be expected to form small, soluble immune complexes, there was no major deleterious effect on radioimmunoscintigraphy.

Animals↗
PubMed1989

Computer simulation of liquid crystals.

We review recent progress in the computer simulation of liquid crystals, with special emphasis on hard particle models. Surprisingly, the simplest molecular models, taking account only of molecular size and shape, are sufficient to generate a wide variety of liquid crystalline phases, closely analogous to those observed in real life. Thermodynamic stability of different phases is very sensitive to shape, and presumably will also be sensitive to further details of intermolecular interactions as they are incorporated into the model. Realistic atom-atom potential models of liquid crystals are available, but the associated simulations are quite expensive. Thus, while idealized models may be used to study quite general, fundamental properties of mesophases, the modelling of specific liquid crystal systems in a realistic way remains a great challenge. Progress continues to be made on both these fronts.

Chemical Phenomena↗
PubMed1989

National survey of the prevalence and risk factors of glaucoma in St. Lucia, West Indies. Part I. Prevalence findings.

Although blacks appear to be at higher risk for blindness from glaucoma, there is little information available on the epidemiology of this disease in this population. Using a cluster sampling technique with systematic allocation of clusters, the authors conducted a national survey of black individuals 30 years of age and older, in St. Lucia. A total of 1679 individuals underwent a screening examination that included visual acuity, intraocular pressure (IOP) measurement, and cup/disc (C/D) evaluation. Every third person had a screening field on the Humphrey field analyzer. Individuals with either elevated IOP, abnormal C/D ratio, or an abnormal screening visual field were referred for a definitive examination and threshold visual fields. A total of 520 people were referred. Identified by stringent criteria for the diagnosis of glaucoma, which required reliable threshold visual fields abnormal by the mirror image method, 147 individuals had glaucoma for a prevalence of 8.8% in the 30 years of age and older population.

Adult↗