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Biomedical subjects

R R Pfister

Publications and source records attributed to R R Pfister.

At least 19 recordsLinked to original sources
PubMed1992

Endopyelotomy associated ureteral necrosis: complete ureteral replacement using the Boari flap.

A case of an adolescent who sustained necrosis of the entire ureter after attempted endopyelotomy for congenital ureteropelvic junction obstruction is presented. Successful reconstruction of a neoureter was performed easily with the Boari bladder flap coupled with nephropexy and a psoas hitch. Although repair of upper ureteral injuries with the Boari flap has been described in the literature, to our knowledge its use in the pediatric population has not. Our case exemplifies how the Boari flap repair is particularly suitable in children for bridging significant segments of injured ureters, not just the lower third.

Adolescent↗
PubMed1992

Serious complications of topical mitomycin-C after pterygium surgery.

BACKGROUND: The use of topical mitomycin (mitomycin-C) as a medical adjunct to pterygium and glaucoma surgery is increasing. METHODS: The authors report on a series of 10 patients who experienced serious, vision-threatening complications associated with the use of this drug after pterygium surgery. RESULTS: Complications included severe secondary glaucoma (4 patients), corneal edema (3 patients), corneal perforation (1 patient), corectopia (2 patients), iritis (8 patients), sudden onset mature cataract (2 patients), scleral calcification (1 patient) and incapacitating photophobia and pain (8 patients). Two patients required penetrating keratoplasties and a third required three lamellar keratoplasties. Another patient underwent four additional surgeries including a conjunctival Z-plasty, scleral patch grafting, and conjunctival autografting before his intractable pain and photophobia resolved 15 months after the original surgery. Because of these complications, 6 patients required a total of 20 return visits to the operating room after their original pterygium surgery. In 5 eyes, visual acuity remained at 20/200 or less. Three of the six patients with the most severe complications had concomitant chronic external diseases (rosacea [3 patients], ichthyosis [1 patient], keratitis sicca [1 patient]). CONCLUSION: The authors urge extreme caution in the use of mitomycin. If mitomycin is used, the lowest possible concentration should be applied for the shortest time period in an effort to avoid these complications. A prospective multicenter study of the ophthalmic use of this medication is needed.

Adult↗
PubMed1992

Subconjunctival injection of purified blood mononuclear cells into alkali-injured rabbit eyes.

Monocytes transform into tissue macrophages that scavenge necrotic debris from wounds but also release substances stimulatory to fibroblasts. In an effort to encourage the healing process, monocytes, purified from rabbit blood, were injected subconjunctivally 1 or 2 days and 6 or 7 days after alkali injury to the rabbit eye. The injected monocytes failed to alter the course of the alkali-injured eyes. Specifically, the incidence of corneal ulceration in the experimental group was not statistically different from that of the control group. A byproduct of this study was a presentation of the technique to purify platelet-free mononuclear leukocytes from rabbit peripheral blood.

Animals↗
PubMed1992

Clinical measures to promote corneal epithelial healing.

It is necessary to know the specific pathobiology of a persistent epithelial defect to determine the strategy to be employed to assist in its repair. Lid position and function must be normal and any deficiency in the quantity and quality of the tears enhanced by tear preparations and closure of the lacrimal canaliculi. Adverse drug effects must be eliminated. Multiple corneal punctures and excision of reduplicated basal lamina have virtually eliminated the problem of recurrent corneal erosions. Control of any inflammatory process also speeds healing. Vitamin supplements, especially A, reverse defects associated with xerophthalmia. In any of these diseases, mechanical treatments consisting of soft contact lenses for persistent epithelial defects and collagen shields for the delivery of antibiotics or steroids to the eye may be employed. Tarsorrhaphy relieves the problem of persistent epithelial defects in neurotrophic keratitis and a variety of other conditions characterized by persistent surface breakdown. Preliminary data from open label studies of epidermal growth factors and fibronectin are encouraging but not yet conclusive.

Animals↗
PubMed1991

A visual assay for quantitating neutrophil chemotaxis in a collagen gel matrix. A novel chemotactic chamber.

The chemotactic behavior of polymorphonuclear leukocytes (PMNs) suspended in a three-dimensional gel of native collagen fibers was analyzed using a new visual assay aided by computer assisted tracking. Cell behavior was observed in a 7 microliters chamber closed at either end with capillary tubes tipped with dialysis membrane. The chemoattractant, LTB4, was placed in one capillary tube and the control substance in the opposite tube. Under microscopic observation neutrophils were videotaped, their images digitized, and the x and y coordinates of the cell centroids captured at 30 s intervals for 15 min and subsequently analyzed. The data generate a global perspective of neutrophil behavior in a medium simulating a collagenous tissue. The results show that when leukotriene B4 was substituted for HBSS the PMN population underwent chemotactic displacement. PMN chemotaxis was increased greatly when the concentration of LTB4 was increased from 10 nM to 1 microM in separate experiments. This result was partly achieved by movement of an increasing percentage of the PMN population, less frequent stops, and longer durations of motility for individual cells. The most dramatic effect of LTB4 on neutrophil behavior was a large increase in directional movement toward the chemotactic source. The effects of LTB4 fell dramatically when the gradient source concentration was increased to 10 microM. The visual assay described here provides clear evidence that LTB4 induces true neutrophil chemotaxis in a collagenous matrix.

Chemotaxis, Leukocyte↗
PubMed1991

The intraocular changes of anterior segment necrosis.

Anterior segment necrosis is an acute or chronic process occasioned by embarrassment of the blood supply of the anterior segment of the eye. In the acute form this vascular obstruction leads to severe corneal oedema, necrosis of anterior uvea, hypotony and cataract formation. Depression of aqueous humour formation accounts for severe reduction of glucose levels in corneal stroma and aqueous humour lasting for two days after cautery of the long posterior ciliary arteries (LPCA) in rabbits. Lactate levels are initially significantly elevated but return to normal after one week. Stromal hydration was elevated for one week but then returned to normal. Corneal epithelial glycogen was diminished at one and two days after surgery but then returned to normal. Although unproven, oxygen deprivation probably plays a major role in endothelial ischaemia and therefore corneal oedema. It is concluded that the abnormalities seen in anterior segment necrosis stem from changes in aqueous metabolic components resulting from severely reduced aqueous turnover. Hyperbaric oxygen and intracameral metabolite substitution are unproven treatments but merit further experimental study.

Animals↗
PubMed1991

The combined effect of citrate/ascorbate treatment in alkali-injured rabbit eyes.

The incidence of ulceration and perforation in the cornea of alkali-injured eyes is significantly reduced by treatment with trisodium citrate or sodium ascorbate. Topical citrate reduces the inflammatory response in the cornea by inhibiting polymorphonuclear leukocytes. Topical ascorbate elevates the depressed level of this vitamin in the alkali-injured cornea, reversing a scorbutic condition. The purpose of the current study was to determine whether combined treatment with topical citrate and ascorbate has an additional therapeutic value when compared with citrate alone. Adsorbotear without EDTA was used as the vehicle for both medications. Rabbit eyes were injured with 1N NaOH for 35 s using a 12-mm well and were rinsed. Group I (47 eyes) received two drops of 10% citrate every hour on the hour and Adsorbotear on the half-hour for 14 h/day. Group II (48 eyes) received two drops of 10% citrate every hour on the hour and 10% ascorbate every hour on the half-hour for 14 h/day. The citrate/ascorbate group had significantly fewer ulcerations during the experiment than did the group receiving citrate alone (2 of 48 versus 10 of 47, 0.01 less than p less than 0.02). Both anterior ulcers in the citrate/ascorbate group and five ulcers in the citrate group healed to no ulcer by the end of the experiment (0 of 48 versus 5 of 47, 0.02 less than p less than 0.05). The average depth of ulceration was significantly less for the citrate/ascorbate group (p less than 0.001). No descemetoceles or perforations were observed in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkalies↗
PubMed1991

Amino acid composition of a neutrophil respiratory burst stimulant. Evidence for a protein, noncollagenous source.

Activation of the neutrophil respiratory burst by the supernatant fraction from an alkali-treated collagen preparations (SAC) was enhanced by longer durations of exposure to alkali (1 N NaOH for 0.5-24 hr). The concentrate obtained from ultrafiltration (greater than 30,000 molecular weight) of SAC (1 N NaOH for 24 hr) retained the stimulatory factor. Fractionation of this ultraconcentrate by high-performance liquid chromatography showed that the stimulatory activity resided in the void volume (highest molecular weight). The amino acid composition of this active fraction revealed that this proteinaceous stimulant was not derived from the collagen molecule. Treatment of the SAC with ultrapure bacterial collagenase increased its stimulatory capacity, confirming its noncollagenous nature. Alkali treatment of whole cornea also released a similar large molecular weight, noncollagenous protein that stimulated the respiratory burst of polymorphonuclear leukocytes. Enhanced stimulation after prolonged NaOH treatment of the collagen preparation or collagenase treatment of SAC suggests that the stimulant might reside between collagen fibrils and then be released as the matrix is degraded.

Amino Acids↗
PubMed1991

Sorption of sodium hydroxide by type I collagen and bovine corneas.

There are no quantitative studies on the uptake of alkali into corneal tissues. To study this phenomenon, both type I collagen and bovine corneas were incubated in sodium hydroxide (NaOH) under varying conditions for periods up to 27.5 h. The sorption (absorption or adsorption) of the alkali to protein and tissue was measured as the quantity of NaOH no longer available for titration to neutrality with hydrochloric acid. Sorption was found to be dependent on the concentration of NaOH (0.01-1 N) but independent of the incubation temperature (4-35 degrees C). In whole cornea, sorption of 1 N NaOH began immediately and increased with time up to 6 h. After 6 h, sorption decreased, together with the observed degradation and solubilization of the tissue. Stripping of the corneal endothelium alone or of the endothelium and epithelium increased sorption in a similar manner when compared to whole corneas for periods up to 4 h. These observations are compatible with ionic and nonionic bonding of hydroxide ions to collagen (including that of the cornea) and the subsequent release of hydroxide ions during hydrolysis of the protein itself. Indirect evidence also suggests the inclusion of quantities of unbound hydroxide ions in hydrated gels of glycosaminoglycans. It is proposed that in a chemical burn of the cornea, alkali is both stored in the tissue (by sorption) and reacted with it (by hydrolysis), without any net consumption of alkali taking place.

Absorption↗
PubMed1990

Topical citrate inhibits the adherence of neutrophils to postcapillary venules.

The high incidence of corneal ulceration in the alkali-injured rabbit eye can be reduced by topical citrate drops. Citrate interferes with polymorphonuclear leukocyte (PMN) accumulation in the corneal stroma after alkali injury. It inhibits the adherence, locomotion, respiratory burst, phagocytosis, and degranulation of human PMNs in vitro. The objective of this research was to determine if PMN adherence to the vascular endothelium could be inhibited by superfused citrate in vivo. PMN adherence to the endothelium of postcapillary venules in the hamster cheek pouch was greatly enhanced and maintained by addition of leukotriene B4 (LTB4) to the superfusate. Superfusion of the pouch with 24 mM citrate for 5 min, before addition of LTB4, inhibited PMN adherence to the endothelium. The free calcium level in the superfusate was reduced from approximately 650 to 33 microM in the presence of 24 mM citrate. When LTB4-augmented PMN adherence was allowed to occur, followed by citrate treatment (24 mM), it was reversed. Simultaneous addition of CaCl2 and MgCl2 to the superfusate raised the free Ca2+ level to 786 microM and reversed the citrate-induced inhibition of LTB4-augmented adherence. From this and other research, we conclude that citrate probably inhibits adherence of PMNs to pericorneal and conjunctival vessels in the eye, preventing their accumulation in the corneal stroma.

Administration, Topical↗
PubMed1989

Degradation of bovine corneal collagen by alkali.

This study was undertaken to demonstrate the effect of alkali on the molecular size of collagen. Type I and V collagen from bovine cornea were incubated with different concentrations of NaOH at room temperature and 37 degrees C for various times. The samples were then neutralized and analyzed by high-pressure liquid chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Degradation of collagen molecules to a heterogeneous mixture of peptides with molecular weights less than 20,000 daltons occurred at concentrations greater than 0.25N, and the effect of alkali was much faster at 37 degrees C than at room temperature. In contrast, the molecular size of collagen was not affected by similar concentrations of HCl under similar conditions of time and temperature.

Alkalies↗
PubMed1989

The efficacy of topical citrate after alkali injury is dependent on the period of time it is administered.

The neutrophilic response in the alkali-injured rabbit cornea can be separated into two peaks: the first from 12-24 hr and the second at 21 days. In the experiments detailed here, alkali-injured rabbit eyes were treated for 0-7 days (early peak), 6-35 days (late peak), or 0-35 days (both peaks) with 6.5% or 10% topical citrate. Clinical evaluation of these eyes showed that treatment with 10% citrate (0-35 days) significantly reduced the incidence and severity of corneal ulceration from the control level. When 10% citrate was administered to block the early neutrophilic peak, the incidence of corneal ulceration was also significantly reduced (33.3% from 72.2%). The average ulcer depth increased gradually, reaching an intermediate level well below the control group by day 35. In contrast, 10% citrate treatment of the late peak had no significant effect on the incidence of ulceration; however, these ulcers were less severe than those in the control. When 6.5% topical citrate (0-35 days) was used, there was a significant reduction in the severity but not the incidence of ulceration. In addition, the beneficial effects obtained from separate treatment of the early and late PMN peaks were mostly lost. These experiments suggest that both the early and late peak of the PMN response after alkali injury are important to the development of corneal ulcers. We hypothesize that the early use of 10% citrate diminishes the initial peak of PMNs, interfering with the release of self-perpetuating inflammatory mediators, thereby decreasing the later accumulation of PMNs that cause ulceration.

Administration, Topical↗
PubMed1988

The effects of citrate on the adherence of neutrophils to nylon fibers in vitro.

The therapeutic effect of citrate on alkali-burned eyes is thought to be the result of inhibition of PMN activities while ascorbate apparently stimulates the production of new collagen by scorbutic fibroblasts. Attachment of PMNs to the vascular endothelium is the initial PMN response to mediators and must occur before diapedesis and chemotaxis can produce a tissue infiltrate. The present study was undertaken to test the effects of citrate or ascorbate on the in vitro adherence of resting and leukotriene B4 (LTB4)-treated PMNs. Citrate preincubation of resting or LTB4-treated PMNs inhibited adherence in a dose-dependent manner. Inhibition of LTB4 augmented adherence by 12 mM citrate was effectively reversed by the addition of Ca2+ and Mg2+ (6 mM each). Ascorbate had no significant effect on the adherence of resting or LTB4 treated PMNs. In addition we wished to test the effectiveness of the breakdown product(s) from alkali burned collagen (Type 1) as an augmentor of adherence because of its effectiveness as a locomotory and respiratory burst stimulant. These break-down product(s) had no effect on the adherence of resting or LTB4-treated PMNs unless bovine serum albumin (BSA) was omitted from the incubation mixture. In the absence of BSA, these breakdown products inhibited both types of adherence in a dose-dependent manner with dilutions from 1:10 to 1:1000. This inhibition is probably not clinically meaningful since PMN adherence takes place in the vasculature where BSA would always be present. As a consequence of citrate inhibition of adherence in vivo, PMNs would be denied access to the injury site, trapping them in a resting state within the circulatory system.

Ascorbic Acid↗
PubMed1988

The effects of oral or intravenous citrate on the activation of neutrophils in vitro.

Topical citrate has been shown to significantly reduce the severity and incidence of corneal ulceration in alkali-burned rabbit eyes. Subcutaneous injection of citrate significantly reduced the severity of ulceration. This study was performed to determine the plasma citrate and ionized calcium levels after systemic administration of citrate. Repeated ingestion of citric acid capsules showed a small increase in the plasma citrate level, but no significant change in the level of ionized serum calcium 30 min after the last ingestion. A single dose of Polycitra-LC (6.672 g of citrate) more than doubled the baseline citrate concentration but only induced a 5% decrease in the level of ionized serum calcium 30 min after ingestion. Neither regimen of orally administered citrate produced any significant effect on the respiratory burst or adherence of in vitro polymorphonuclear leukocytes (PMNs) resuspended in their respective plasma. In comparison studies, higher levels of plasma citrate and lower levels of ionized serum calcium were achieved through plateletpheresis. The respiratory burst and adherence of PMNs were not statistically different from baseline PMNs. However, there was an inverse correlation between the micromolar increase in citrate or the micromolar decrease in calcium and the respiratory burst. These results suggest that the use of oral citrate alone may not be practical, but does not preclude the use of oral citrate as a supplement to topical citrate.

Administration, Oral↗
PubMed1988

Preliminary characterization of a polymorphonuclear leukocyte stimulant isolated from alkali-treated collagen.

This study reports the preliminary characterization of a stimulant released from alkali-treated collagen which activates the respiratory burst of PMNs. The supernatant fraction from alkali-treated collagen (SATC) was precipitated with ammonium sulfate, resuspended, and centrifuged through a sucrose gradient (10-30%, W/V). Proteins were detected throughout the gradient but PMN stimulatory activity was found mainly in fractions 1 and 2 (bottom of gradient), indicating a very high molecular weight. When SATC was layered on a denser sucrose gradient (20-85%, W/V), protein was spread over the upper half of the gradient. The peak of PMN stimulatory activity was found in the middle of the gradient (fractions 8 and 9), indicating a molecular weight similar to the 200,000 dalton standard. High pressure liquid chromatography (HPLC) of fractions from this heavier sucrose gradient showed a small peak, followed by a much higher main peak. The small peak, with the highest molecular weight peptide, is responsible for stimulation of the respiratory burst of PMNs (fraction 8 and 9). The source of this stimulant is yet to be determined.

Alkalies↗
PubMed1988

Citrate or ascorbate/citrate treatment of established corneal ulcers in the alkali-injured rabbit eye.

Immediate treatment of alkali-injured eyes with citrate or ascorbate has previously been shown to prevent corneal ulceration and perforation in the rabbit. Other experiments showed that while ascorbate treatment of established ulcers did not appear to lead to significant healing it did reduce perforations by prolonging the presence of descemetoceles. In the present experiment with established ulcers, alkali injuries were created with 1 N NaOH in a 12 mm corneal well for 35 seconds. Eyes were entered into the study with anterior, middle or posterior ulcers. When compared to controls, 10% citrate (q1/2 hr) significantly reduced the deepening of anterior stromal ulcers while 10% ascorbate/10% citrate (q1 hr/q1 hr-30 min apart) showed only a trend toward reduction of these ulcers (14 hr of dropping). The demonstration of healing (total vascularization or no ulcer) is significant when comparing the control group (8.3%) to the citrate treated group (58.3%, 0.01 less than P less than 0.009), but not the ascorbate/citrate group (18.2%). Sixty-seven percent of anterior stromal ulcers in the control group progressed to descemetocele or perforation, compared to 8.3% in the citrate treated (0.003 less than P less than 0.004), and 45.5% in the ascorbate/citrate treated group (not significant). While the numbers of ulcers entered as middle stromal were too few to analyze statistically, the reduced numbers of perforations and increased stability prior to perforation in both treatment groups suggest a positive effect by both citrate and ascorbate/citrate. Treatment of posterior stromal ulcers did not prevent the development of descemetoceles and perforations in either treatment group; however, the numbers in this category were too few to analyze.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Urethral duplication and complete bladder exstrophy.

Urethral duplication is a rare anomaly that has been classified into epispadiac, hypospadiac, spindle, Y-duplications and collateral varieties. We report a case of an accessory urethra associated with complete bladder exstrophy in which the accessory urethra was integrated into the epispadias repair. To our knowledge this is the first case reported of urethral duplication associated with bladder exstrophy.

Abnormalities, Multiple↗