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Biomedical subjects

R P Wilson

Publications and source records attributed to R P Wilson.

At least 19 recordsLinked to original sources
PubMed1992

Antinociceptive properties of tiletamine-zolazepam improved by addition of xylazine or butorphanol.

A combination of tiletamine HCl and zolazepam HCl is frequently used as an anesthetic, but little is known about the antinociceptive properties of tiletamine-zolazepam. The antinociceptive properties of tiletamine-zolazepam alone or combined with xylazine or butorphanol were determined in the adult male rate using the tail-flick test. Changes in tail-flick latency were determined at 15, 45, and 75 min after IP drug administration of sterile water, sodium pentobarbital, morphine, tiletamine-zolazepam, xylazine, butorphanol, and tiletamine-zolazepam plus xylazine or butorphanol. Tail-flick latency approximated 100% maximum possible effect (MPE) at 15-75 min postinjection in morphine-treated rats. Tiletamine-zolazepam, xylazine, and butorphanol alone, at any dose utilized, produced less than 50% MPE. However, the combination of tiletamine-zolazepam with butorphanol or xylazine increased tail-flick latency approximately three times greater than tiletamine-zolazepam alone. These results demonstrate that: a) consonant with earlier findings, analgesia and anesthesia are independent states; b) tiletamine-zolazepam is not an effective combination with respect to analgesia; but c) in concert with appropriate drugs, it can exhibit potent antinociceptive properties.

Analgesics↗
PubMed1992

Aqueous shunts. Molteno versus Schocket.

The authors conducted a multicenter, randomized, controlled trial to test whether the Schocket shunt with a larger shunt reservoir surface area would provide a lower final intraocular pressure than the double-plate Molteno implant. However, the Molteno implant produced a statistically lower intraocular pressure at 6 months compared with the Schocket shunt. Postoperative visual acuity, glaucoma medications, and complications were not statistically different.

Aqueous Humor↗
PubMed1992

Anterior chamber tube shunt to an encircling band (Schocket procedure) in the treatment of refractory glaucoma.

We reviewed a series of 42 eyes in patients with refractory glaucoma who had undergone a Schocket procedure. The mean follow up was 17.5 months; the minimal follow up, 8 months. The success rate was 81%, with "success" defined as either (1) an intraocular pressure less than 21 and greater than 5 mm Hg, with a pressure reduction of at least 10%, and less or no medication; or (2) a pressure reduction of at least 30%, with no change of medication. When eyes with a loss of more then one Snellen line of visual acuity were interpreted as failures, the success rate dropped to 61%. Forty percent of all cases required revision. In four cases, the shunt had to be removed (three cases due to hypotony and one secondary to conjunctival erosion). These results are in the range of those obtained by other investigators using this technique or other tube-shunt procedures.

Adolescent↗
PubMed1992

Surgical and medical management of patients with narrow anterior chamber angles: comparative results.

We retrospectively reviewed case records of 70 patients (114 eyes) to assess long-term outcome of surgical and medical treatment of narrow anterior chamber angles. Fifty eyes had undergone a peripheral iridectomy, incisional or laser; 64 had been treated medically, without surgery. The two groups were not strictly comparable. (It is assumed but not proven that, since iridectomy was considered necessary in one group and not in the other, the surgically-treated patients were more seriously diseased.) Comparing clinical data obtained at the first visit with data obtained at the last visit, the eyes receiving iridectomies, as compared with those receiving medical treatment alone, showed a greater number of improved anterior chamber configurations (74% vs 28%), had a lower incidence of peripheral anterior synechiae (2% vs 10%), and required fewer glaucoma medications (30% fewer vs 10% fewer). The percentage of eyes with increased intraocular pressure was similar in both groups (36% vs 28%), as was the percentage of those with decreased visual field (17% vs 21%) and decreased visual acuity (66% vs 60%). No significant complications occurred in the eyes receiving laser iridectomies; however, one of the incisionally-treated eyes lost nine Snellen lines of vision.

Anterior Chamber↗
PubMed1991

The cost of a hot meal: facultative specific dynamic action may ensure temperature homeostasis in post-ingestive endotherms.

1. Resting metabolic rate was determined in Adelie penguins (Pygoscelis adeliae) that had been fed warm and cold ingesta. 2. Post-ingestion metabolic rate was found to be related to food temperature rather than to specific dynamic action. 3. Calorimetric calculations indicate that up to 13% of Adelie penguin daily energy expenditure may be used heating ingested food to body temperature. 4. Heating food costs are predicted to be higher in endotherms living in cold regions and in species with low assimilation efficiencies, but may be minimized by appropriate foraging behaviour.

Animals↗
PubMed1991

Use of trabeculectomy with postoperative 5-fluorouracil in patients requiring extremely low intraocular pressure levels to limit further glaucoma progression.

The authors conducted a randomized, controlled clinical trial to quantify the effect of 5-fluorouracil (5-FU) on filtration surgery. Both eyes of 17 patients with either bilateral low-tension glaucoma or advanced chronic open-angle glaucoma that would be expected to progress at intraocular pressures in the normal range were included. One eye received a full-thickness filtering procedure with a modified shell tamponade technique, and the other received a trabeculectomy with postoperative 5-FU. Follow-up was equal for both eyes and averaged 9.2 months. In eyes in the shell group, the average postoperative pressure was 10.94 mmHg, and in the 5-FU group it was 6.94 mmHg, (P = 0.0001). However, the postoperative visual acuity decrease was significantly greater in the 5-FU group (P less than 0.05). Choroidal detachments also were more frequent in the 5-FU group, but this was not statistically significant.

Aged↗
PubMed1990

Ab interno laser sclerostomy in aphakic patients with glaucoma and chronic inflammation.

Five patients with aphakia, glaucoma, and chronic inflammation were treated with ab interno sclerostomy by using the continuous wave Nd:YAG laser focused through a sapphire probe. After a follow-up period of 24 to 28 months, three of five patients had good intraocular pressure control. The sclerostomy failed in one patient when it was occluded by vitreous. The second failure was attributed to closure of the sclerostomy because of chronic intraocular inflammation.

Aged↗
PubMed1990

Energy requirements of Adélie penguin (Pygoscelis adeliae) chicks.

The energy requirements of Adélie penguin (Pygoscelis adeliae) chicks were analysed with respect to body mass (W, 0.145-3.35 kg, n = 36) and various forms of activity (lying, standing, minor activity, locomotion, walking on a treadmill). Direct respirometry was used to measure O2 consumption (VO2, l.h-1) and CO2 production. Heart rate (HR, bpm) was recorded from the ECG obtained by both externally attached electrodes and implantable HR-transmitters. The parameters measured were not affected by hand-rearing of the chicks or by implanting transmitters. HR measured in the laboratory and in the field were comparable. Oxygen uptake ranged from VO2 = 1.50.W0.921 in lying chicks to VO2 = 2.25.W1.024 at maximal activity, RQ = 0.76. Metabolic rate in small wild chicks (0.14-0.38 kg) was not affected by time of day, nor was their feeding frequency in the colony (Dec 20-21). Regressions of HR on VO2 were highly significant (p less than 0.0001) in transmitter implanted chicks (n = 4), and two relationships are proposed for the pooled data, one for minor activities (VO2 = -7.23 + 1.82.W + 0.03 HR), and one for walking (VO2 = -11.89 + 1.117.W + 0.058.HR). Oxygen consumption, mass of the chick (2-3 kg), and duration of walking (T, s) were related as VO2 = -0.746 + 1.87.W + 0.076.T, whereas mass-specific O2 consumption was related to walking speed (S, m.s-1) as VO2.W-1 = 1.60 + 7.39.S.

Animals↗
PubMed1990

The chamber-retaining suture revisited.

In 1977, C. William Simcoe developed the anterior chamber-retaining suture as a means of preventing intraocular lens-cornea touch during intraocular lens manipulation, penetrating keratoplasty, and following filtration surgery. Though seldom remembered today, Simcoe's innovation safely and effectively insures corneal well-being following increasingly complex modern filtration and shunt procedures. The use of a combination of double-armed 9-0 nylon suture and anterior chamber-bridging straight needles simplifies placement.

Anterior Chamber↗
PubMed1989

Sharing food in the stomachs of seabirds between adults and chicks--a case for delayed gastric emptying.

1. Retention times of food in stomachs of breeding and non-breeding African pengiuns (Spheniscus demersus) were examined. 2. Rates of gastric emptying in non-breeding birds were linearly related to the mass of food in the stomach. 3. Breeding birds returned to the nest with more food in their stomachs when chicks were larger. The rate of regurgitation of food was linearly related to chick mass. 4. Retention times of food in the stomachs of breeding penguins can only be explain by cognisance of observed regurgitation rates and by assuming that there is no gastric emptying through the pyloric sphincter.

Animals↗
PubMed1989

Risk factors for the development of Tenon's capsule cysts after trabeculectomy.

Tenon's capsule cysts (TCCs) are a complication of glaucoma filtering surgery. They are frequently associated with substantial elevations in intraocular pressure (IOP) beginning 2 to 8 weeks postoperatively. To determine the incidence and possible risk factors for the development of TCCs, case records of all patients who received trabeculectomy over a 4-year period at the Wills Eye Hospital were reviewed. The incidence of TCCs was 28% in those who underwent trabeculectomy. Characteristics of patients after trabeculectomy in whom TCCs developed were compared with patients after trabeculectomy in whom TCCs did not develop. Both univariate and multivariate techniques were used to assess the association of characteristics associated with the development of TCCs. Factors associated with increased risk (P less than 0.05) were: history of prior TCCs, argon laser trabeculoplasty, male gender, and the use of preoperative sympathomimetics. The use of a compression shell was associated with decreased risk (P less than 0.05).

Adult↗
PubMed1989

Effect of dietary n-3 fatty acids on weight gain and liver polar lipid fatty acid composition of fingerling channel catfish.

A 10-wk experiment was conducted to determine the effect of supplementing a 5% tristearin basal diet with linoleic acid [18:2(n-6)], linolenic acid [18:3(n-3)], an n-3 highly unsaturated fatty acid (n-3 HUFA) mixture, cod liver oil, corn oil or linseed oil on growth and fatty acid composition of the liver polar lipid fraction of fingerling channel catfish (Ictalurus punctatus). The lowest weight gain was observed in fish fed the basal diet. Weight gain was improved by certain levels of supplemental n-3 fatty acids. Fish fed a diet containing 2% 18:3(n-3) grew at the same rate as fish fed a diet containing 2.5% cod liver oil plus 2.5% corn oil. The best growth rate was observed in fish fed diets containing either 5% cod liver oil or 5% linseed oil. Growth rate was depressed by supplementation with 4% 18:3(n-3) or 1.25% n-3 HUFA mix. No improvement in growth rate was observed with dietary 18:2(n-6). Dietary linolenate was converted to docosahexaenoic acid [22:6(n-3)]. The ratio of 20:3(n-9) to 22:6(n-3) of the fish showing good growth was less than 0.4. The data obtained in this experiment indicate that n-3 fatty acids are essential for channel catfish and that the 18:3(n-3) or n-3 HUFA dietary requirement is 1.0-2.0% or 0.5-0.75%, respectively.

Animals↗
PubMed1989

Neodymium: YAG laser transscleral cyclophotocoagulation for glaucoma after penetrating keratoplasty.

Nd:YAG laser cyclophotocoagulation (CPC) of the ciliary body is a promising cyclodestructive treatment for the management of refractory glaucoma following penetrating keratoplasty. Twenty-eight eyes (27 patients) were treated between August 1985 and September 1987 and followed 6 to 24 months (median, 18 months). The mean intraocular pressure (IOP) was initially 39 mm Hg (range, 30 to 70 mm Hg) on maximally tolerated medications. The Lasag Microrupter 2 was used in the free-running thermal mode with a mean pulse energy of 4.13 J. The laser was retrofocused 3.6 mm from the conjunctival surface and 30 to 50 applications per treatment (mean, 37.5) were given 2 to 3 mm from the limbus for 360 degrees (71%) or 180 degrees (29%). Multiple treatments were necessary in 13 eyes (46%). After CPC, IOP fell to 22 mm Hg or below in 18 eyes (64%) at 3 months, in 20 of 27 eyes (74%) at 6 months, and in 16 to 24 eyes (67%) at 1 year. Inadequate IOP control in four of 28 eyes necessitated cyclocryotherapy in three patients and a Schocket procedure in one other. Of the 14 clear pre-CPC grafts six (43%) became edematous during follow-up. All of the failed grafts had undergone multiple CPCs.

Follow-Up Studies↗
PubMed1989

Laser sclerostomy ab interno using a continuous wave Nd:YAG laser.

We report the use of a continuous wave Nd:YAG (CW-YAG) laser focused through a sapphire crystal to create a filtering bleb by ab-interno sclerostomy. A 2-mm clear corneal incision was made in each eye of five anesthetized Dutch Belted rabbits, and the 30-mm-long sapphire crystal with a 0.2-mm focal tip was passed across the anterior chamber until it came in contact with the opposite angle. Between two and three pulses of 0.8 J were required to produce a filtering bleb in each of the 10 eyes. The overlying conjunctiva was not damaged; the procedure time was under five minutes. Histological examination revealed a surrounding area of scleral melting that extended an average of 0.06 mm from the sclerostomy. These data suggest that the CW-YAG laser may be useful in performing glaucoma filtering surgery with minimal damage to surrounding ocular tissues.

Animals↗
PubMed1988

Variability in digital analysis of optic disc topography.

We determined the magnitude of variability in optic disc topographical parameters on digital analysis of the optic disc using the IS 2000. The variability introduced by the system, the observer, the observer and patient, and by clinically different types of discs was assessed in the measurement of the vertical cup-to-disc ratio, horizontal cup-to-disc ratio, cup area-to-disc area, cup volume, neuroretinal rim area, and neuroretinal rim area-to-disc area. The system itself accounted for no variability. The variability introduced by one observer for the parameters ranged from 1% to 7%, and by one observer and patient from 1% to 28%. The variation among five observers ranged from 1% to 55%. Direct image acquisition (using video cameras) gave results that were no different from those obtained by digitizing the slides. Contrast-enhancement techniques did not decrease observer variability. A change in the flash intensity level at which optic disc images were acquired from 94.5 to 15.0 Watt-seconds introduced a variability of 3% to 21%. These results are less variable than those obtained on clinical observation and comparable to those of the Rodenstock image analyzer in evaluating these aspects of optic disc topography.

Adult↗
PubMed1988

Surgical therapy of chronic glaucoma in aphakia and pseudophakia.

Most glaucoma surgical procedures are less successful in aphakic or pseudophakic eyes. The authors reviewed 91 consecutive initial glaucoma procedures in aphakic patients from 1979 to 1986 to determine successful outcomes and complications. Success was defined as an intraocular pressure (IOP) of at least 30% below the preoperative value and less than 21 mmHg, less than 2 lines of Snellen acuity loss, and no further surgical intervention. At 9 months, success rates were: trabeculectomy, 4 of 15 patients; cyclodialysis, 3 of 20 patients; neodymium:YAG (Nd:YAG) cyclophotocoagulation, 1 of 8 patients; cyclocryotherapy, 9 of 22 patients; anterior chamber tube shunt (Schocket procedure), 3 of 6 patients; and argon laser trabeculoplasty, 2 of 20 patients. Severe complications included phthisis bulbi in 11% of cyclocryotherapy and severe visual loss in 20% with cyclodialysis and 14% with cyclocryotherapy. Results confirm the difficulty of surgical therapy in these patients.

Aged↗
PubMed1987

Cysts of Tenon's capsule following filtration surgery. Medical management.

Cysts of Tenon's capsule (encapsulated blebs) developed postoperatively in 77 (13%) of 607 eyes that underwent filtration surgery between 1980 and mid-1985. The annual incidence was not uniform, increasing markedly throughout the period. Seventy-four eyes were treated with medical therapy only. At a mean follow-up of 19 months, the success rate for these eyes, defined as an intraocular pressure (IOP) of 21 mm Hg or less, was 92%. The three eyes that underwent surgical revision subsequently failed clinically by the study criteria. Those patients in whom cysts of Tenon's capsule developed were compared with an age-matched control group to assess for possible differences in long-term outcome. There was a significantly higher IOP in the Tenon's cyst group at one and three months after surgery, and an increased proportion of IOPs above 30 and 40 mm Hg. At a six-month and later follow-up, there was no significant difference in the mean IOP or in progression of visual field loss. Causative factors were sought for the development of these cysts of Tenon's capsule. Prior conjunctival surgery, or previous cyst formation in the other eye, were the significant risk factors noted.

Adolescent↗