Search PubMed⌕ Search

Biomedical subjects

L A Wilson

Publications and source records attributed to L A Wilson.

At least 91 records · Page 5Linked to original sources
PubMed1990

Spontaneous bleeding from a normal-appearing iris: an unusual cause of atypical amaurosis fugax.

Amaurosis fugax, or fleeting loss of vision, is often attributed to embolic retinovascular disease. In this setting, there is appropriate concern for associated cerebrovascular complications. Extensive and expensive vascular evaluation may be indicated. Less often, local ocular abnormalities may mimic embolic visual loss. We describe a case of sudden, transient, monocular visual loss in a 67-year-old woman caused by Valsalva-induced intraocular bleeding from a seemingly normal iris.

Aged↗
PubMed1990

Antibacterial effects of previously infected or inflamed vitreous.

The authors investigated the ability of vitreous harvested from eyes previously infected with Staphylococcus epidermidis or inflamed with heat-killed cells of the same organism to support subsequent in vitro bacterial growth. Growth of S. epidermidis and S. aureus was not supported by previously inflamed or previously infected vitreous, but Pseudomonas aerugnosa grew in all samples. These findings suggest induction of an antistaphylococcal substance by infection or inflammation of rabbit vitreous by S. epidermidis.

Animals↗
PubMed1990

Spontaneous sterilization in experimental Staphylococcus epidermidis endophthalmitis.

We created a standardized model of endophthalmitis in the aphakic rabbit eye using a laboratory strain of Staphylococcus epidermidis of known characteristics (ATCC 155). Eyes were injected with the following number of organisms: 170, 3760, 8750, 170,000 and 460,000. Serial quantitative cultures, clinical grading of infection and histopathologic studies were performed on days 1, 2, 3, 7 and 14. Bacteria appeared to multiply rapidly during the first 24 hr with peak recovery at 8 to 24 hr. Fewer bacteria were cultured on the third day after injection, and positive cultures were rare after the third day. Inflammatory scores were initially higher with each increased number of injected bacteria and tended to increase for the first 3 to 5 days.

Animals↗
PubMed1989

Mass spectrometric approaches to the confirmation of maduramicin alpha in chicken fat.

Because of the structural information it provides, mass spectrometry has gained widespread acceptance as the preferred analytical technique for drug residue confirmatory procedures. For the confirmation of the polyether ionophore antibiotic, maduramicin alpha, in chicken fat, the techniques of desorption chemical ionization (DCI), thermospray liquid chromatography/mass spectrometry (TSP LC/MS), and thermospray liquid chromatography/tandem mass spectrometry (TSP LC/MS/MS) were investigated as potential approaches. Sample clean-up was found to be totally inadequate for DCI and only marginally acceptable for TSP LC/MS. Only TSP LC/MS/MS adequately resolved the analyte from the tissue coextractives and generated satisfactorily reproducible mass spectrometric data for a confirmatory method. The techniques developed here should be applicable to other commonly used polyether ionophores.

Animals↗
PubMed1989

Compartmentalization of intraalveolar and systemic lipopolysaccharide-induced tumor necrosis factor and the pulmonary inflammatory response.

Tumor necrosis factor-alpha (TNF), a monokine produced by lipopolysaccharide (LPS)-stimulated macrophages, is an activator of phagocytic functions and may modulate host responses during infection. To determine the effects of LPS on TNF activity and the pulmonary inflammatory response in vivo, we challenged rats systemically or intratracheally with LPS. Intravenous LPS significantly increased serum TNF content from nondetectable levels in control specimens to peak levels at 90 min, which declined to baseline by 3 h. In response to intratracheal LPS, levels of TNF both in bronchoalveolar lavage fluid and associated with alveolar macrophages increased significantly from near nondetectable levels in control animals. Increases in TNF levels were confined to the LPS-challenged compartment. Intravenous LPS resulted in a decrease in the number of peripheral blood neutrophils and in sequestration of these cells within the pulmonary vasculature. In contrast, intratracheal LPS elicited a marked intraalveolar inflammatory response.

Animals↗
PubMed1989

Temporal response of lipoprotein lipase-suppressing mediator and tumor necrosis factor in lipopolysaccharide -injected and -infused rats.

This study was initiated to compare the temporal response of serum lipoprotein lipase-suppressing mediator (LSM) and tumor necrosis factor (TNF) in lipopolysaccharide (LPS) -infused or -injected rats. Serial blood samples were obtained over a 5-day period from rats implanted with vascular catheters. Control rats infused with saline exhibited no detectable LSM activity during the 5-day observation period. LPS administered either by injection or infusion (6 h or 5 d) resulted in detection of serum LSM and TNF activities during the early period of observation with the LSM temporal response (8 h) outlasting the TNF response (3 h). The LSM response lasted a little longer in LPS-infused rats than it did in injected rats, but in each case LSM activity was not detected in serum samples collected at or after 12 h post-LPS. Neither the duration nor the magnitude of the TNF response differed between LPS-infused vs. -injected rats. Despite similarities in the LSM and TNF pattern in all rats receiving LPS, lethality was greater in LPS-infused animals than it was in LPS-injected rats. The results indicate that differences in lethality between LPS-injected and -infused rats cannot be explained solely by a differential response of serum TNF.

Animals↗
PubMed1988

Late bacterial and fungal keratitis after corneal transplantation. Spectrum of pathogens, graft survival, and visual prognosis.

The authors reviewed 108 bacterial and fungal corneal ulcers that developed 1 to 72 months after penetrating keratoplasty in 79 eyes of 78 patients. Graft hypesthesia, topical corticosteroid and antibiotic treatment, exposed sutures, epithelial defects, and poor visual acuity commonly predated infectious keratitis. There were 69 bacterial, 34 fungal, and 5 combined infections. Candida albicans and Staphylococcus epidermidis were the most common pathogens. Follow-up after infection averaged 23 months (range, 1-80 months). Despite hospitalization and fortified topical antibiotic treatment, complications such as wound dehiscence and corneal perforation necessitated emergency regraft in 38 (35%) cases. Of 73 previously clear grafts, only 29 (40%) retained clarity. Median visual acuity, 20/200 before infection, fell to counting fingers at last follow-up; 12 eyes lost light perception.

Adolescent↗
PubMed1988

Effects of continuous and interval training on the parameters of the power-endurance time relationship for high-intensity exercise.

The purpose of this study was to evaluate the effects of 6 weeks of low-intensity continuous exercise training (CE; 40 min at 50% VO2peak, 3 days/week) and high-intensity interval exercise training (IE: 10 x 2 min at VO2peak, 3 days/week) on the parameters of the power-endurance time relationship for cycle ergometry. The hyperbolic relationship between power and endurance time was linearized by expressing the power against the inverse of time, as described by Whipp et al. (22). This model consists of two parameters: theta f, a fatigue threshold reflecting the capability for sustained aerobic power, and W', a constant postulated to reflect a finite energy store (i.e., those factors comprising the O2 deficit: Phosphagen stores, anaerobic glycogenolysis, myoglobin O2 stores). Prior to training, test-retest reliability coefficients (r2) for theta f and W' were 0.92 and 0.62, respectively (P less than 0.01). Training resulted in significant (P less than 0.01) increases in theta f for both CE [27 +/- 3 W (13.4%) increase] and IE [33 +/- 5 W (15.0%) increase], with no difference between groups. Increases in theta f were not dependent upon improvements in VO2peak. W' was not changed significantly in either group after training. However, a significant negative correlation between the training-induced changes in theta f and W' (R = 0.76; P less than 0.01) was obtained. The minimum intensity threshold for exercise training necessary to elicit increases in theta f has yet to be identified, but is at least as low as 50% of VO2peak.

Adult↗
PubMed1988

Effects of protein, mucin, and human tears on adherence of Pseudomonas aeruginosa to hydrophilic contact lenses.

Pseudomonas aeruginosa isolated from a corneal ulcer was examined for its ability to adhere to hydrophilic contact lenses with adsorbed organic films. Generally, adherence was enhanced by mucin, lactoferrin, lysozyme, immunoglobulin A, bovine serum albumin, and a mixture of these macromolecules. The water content of the lenses also influenced bacterial adherence and protein adsorption. Adherence to lenses coated with human tear films was more complex; both enhanced and inhibited adherence were observed on lenses obtained from different individuals.

Bacterial Adhesion↗
PubMed1988

Role of vitrectomy in Staphylococcus epidermidis endophthalmitis.

Seventeen patients with endophthalmitis due to coagulase-negative staphylococcus were treated over a nine-year period with vitrectomy, intraocular antibiotics, and systemic steroids and antibiotics. Fifteen patients presented with moderate to severe disease and visual acuities from counting fingers to light perception, while two had acuities of 20/60 and 20/200. A final visual outcome of 20/70 or better was achieved in 13 of 17 eyes (76%). Only one eye lost perception of light secondary to retinal detachment. Therapy including vitrectomy is an effective means of controlling moderate to severe coagulase-negative staphylococcal endophthalmitis and restoring vision.

Anti-Bacterial Agents↗
PubMed1988

Glucose kinetics in rats infused with endotoxin-induced monokines or tumor necrosis factor.

This study was conducted to determine if macrophage elaborated monokines in general, and human recombinant tumor necrosis factor (hrTNF alpha) in particular alter glucose metabolism in a manner analogous to that observed in endotoxin-treated animals. Endotoxin-tolerant rats were infused for 3 hr with saline, E. coli endotoxin (100 micrograms/l weight) or monokines contained in conditioned media from endotoxin-stimulated RAW 264.7 cells (1 microgram/ml). Compared to saline- and endotoxin-infused rats, animals receiving the monokine mixture had no change in mean arterial blood pressure or heart rate but exhibited overt signs of morbidity including stupor and diarrhea. Monokine-infused rats remained euglycemic but had elevated lactate concentrations and a 15-30% increase in glucose rate of appearance (Ra). Nontolerant rats received a 3 hr infusion of saline, hrTNF alpha (15 micrograms/100 g), or heat-treated hrTNF alpha. HrTNF alpha infusion increased glucose Ra about 25% compared to the two control groups but did so without producing signs of morbidity seen in the monokine infused animals. Serum TNF levels were 6-fold higher in rats infused with the monokine mixture compared to animals infused with hrTNF alpha, and this reflected the different levels of TNF contained in the monokine mixture and hrTNF alpha infusates. Plasma insulin, glucagon, and catecholamine concentrations were increased in rats infused with either the monokine mixture or hrTNF alpha, but the increases were more pronounced in rats receiving the monokine mixture. The results demonstrate that monokines and hrTNF alpha increase glucose production in vivo, and that the effect may be mediated by endocrine changes known to influence glucose homeostasis.

Animals↗
PubMed1987

Chronic bacterial endophthalmitis.

We studied a specific syndrome of uveitis secondary to intraocular bacterial pathogens of low virulence after extracapsular cataract extraction and intraocular lens implantation in three eyes. The onset of photophobia, visual impairment, conjunctival redness, and uveitis was delayed for four days to 12 weeks after surgery. Chronic inflammation persisted for five weeks to 16 months before a definitive diagnosis was made. Signs and symptoms were suppressed by administration of topical and systemic corticosteroids. Intraocular biopsy and antibiotic injection both established the cause as bacterial endophthalmitis and resulted in resolution of signs and symptoms. Staphylococcus epidermidis was cultured in two eyes and Achromobacter was cultured in one.

Adrenal Cortex Hormones↗
PubMed1987

Penetrating keratoplasty for herpes simplex keratitis and keratoconus. Allograft rejection and survival.

To determine the relationship between corneal allograft rejection and failure, we studied patients who underwent penetrating keratoplasty for herpes simplex keratitis (n = 82) and keratoconus (n = 345), two frequent indications for keratoplasty in young patients, using survival analysis. For first grafts for herpes, the probability of survival was significantly less than it was for keratoconus (P less than 0.0001). For second grafts, this difference was less pronounced, and for three or more grafts, the difference in survival was not significant. The incidence of rejection episodes was similar in first grafts for herpes (16.6%) and keratoconus (18.5%) (P greater than 0.05). However, the incidence of rejection episodes in regrafts for herpes was significantly greater than in keratoconus (23.7 versus 17%, P less than 0.01). The incidence of failure after rejection episodes (first grafts and regrafts combined) was significantly greater in grafts for herpes (52.4 versus 16.2%, P less than 0.001). Because survival after multiple regrafts in both groups is poor, additional measures, such as tissue matching, may be necessary to improve the likelihood of success in these high-risk cases.

Adolescent↗
PubMed1987

Survival of corneal grafts from donors supported by mechanical ventilation.

Eighty-five patients undergoing penetrating keratoplasty with tissue from donors supported by mechanical ventilation (Ventilator group) were compared to a surgeon- and diagnosis-matched group (Control group). Age at surgery, duration of follow-up, and sex of recipient patients were similar in the two groups. The mean donor age in the Ventilator group (26.4 years) was significantly less than in the Control group (45.8 years, P less than 0.0001). Mean time on the ventilator was 99.4 hours (range, 4 hours to 21 days). Overall graft survival rates in the Ventilator and Control groups were similar (P greater than or equal to 0.72). Time on the ventilator did not affect graft survival. Cultures of corneoscleral donor rims were positive more often in the Ventilator group than in Controls (39.7 versus 23.1%), but the difference was not significant (P = 0.09). Prolonged ventilator time was not associated with a higher rate of positive corneoscleral rim cultures, nor did positive cultures affect graft survival. The most common cause of graft failure in both groups was allograft rejection. In no case could postoperative bacterial infection be attributed to contamination of the donor material. One case of primary donor failure occurred in the Ventilator group, but the incidence (1.2%) is similar to that of previously reported studies. The data indicate that corneal tissue from ventilator-supported donors should be considered for use in penetrating keratoplasty.

Adolescent↗