Search PubMed⌕ Search

Biomedical subjects

H W Thompson

Publications and source records attributed to H W Thompson.

At least 37 records · Page 2Linked to original sources
PubMed1998

Trifluridine, cidofovir, and penciclovir in the treatment of experimental herpetic keratitis.

OBJECTIVE: To compare trifluridine eyedrops, cidofovir eyedrops, and penciclovir ophthalmic ointment for the treatment of herpes simplex virus type 1 keratitis. METHODS: New Zealand white rabbits were infected with the McKrae strain of herpes simplex virus type 1. Three days after viral inoculation, the rabbits were randomly assigned to treatment with 1% trifluridine, 0.2% cidofovir, 3% penciclovir ointment, or phosphate-buffered saline (for control) on various schedules. The severity of keratitis was graded in a masked manner. RESULTS: Treatment with any of the antiviral drugs resulted in significantly less severe keratitis than treatment with phosphate-buffered saline. There was no statistically significant difference between eyes given trifluridine 2, 4, or 7 times a day and eyes given cidofovir 2 times a day (P=.06, P=.43, and P=.19, respectively, using the F test of the analysis of variance). Cidofovir given twice a day was significantly more effective than penciclovir given either 2 or 4 times a day (P<.001 and P=.002, respectively). Even with once-a-day dosage, all 3 drugs were significantly more effective than phosphate-buffered saline (P<.001 for all). There was no significant difference between once-a-day trifluridine and cidofovir treatments (P=.17). Trifluridine administered 5 times a day was as effective as 1% cidofovir. A similar degree of punctate keratitis was seen after 4 to 5 days in eyes treated with trifluridine at the highest frequency, 1% cidofovir, or penciclovir ointment. CONCLUSION: Trifluridine treatment was highly effective in this rabbit model, even when given only once a day. Treatment with cidofovir was as effective as that with trifluridine. CLINICAL RELEVANCE: Cidofovir and penciclovir treatments may prove to be effective against epithelial keratitis. Clinical trials of trifluridine, cidofovir, and penciclovir with lower treatment frequencies appear to be warranted.

Acyclovir↗
PubMed1998

Treatment of congenital afibrinogenemia with cryoprecipitate collected through a plasmapheresis program using dedicated donors.

A child with afibrinogenemia was evaluated for prophylactic cryoprecipitate transfusion due to recurrent episodes of traumatic bleeding. The parents would only consider ongoing transfusion therapy if a limited donor program could be established. Automated plasmapheresis was performed on a regular basis on the patient's parents and a limited number of selected donors. Studies on the initial units collected demonstrated that a single 500 mL plasmapheresis yielded a mean of 606 mg fibrinogen in the cryoprecipitate, which was stored in two bags. A total of 166 U of cryoprecipitate from 84 individual plasmapheresis donations were transfused prophylactically every 2-3 weeks over a 16-month period. Compared to transfusions from random donors, the use of a limited number of apheresis donors resulted in a donor exposure reduction of 87%. Clinically, the patient has had minimal bleeding during this period.

Afibrinogenemia↗
PubMed1998

Expression of c-Fos protein in the spinal cord after brachial plexus injury: comparison of root avulsion and distal nerve transection.

OBJECTIVE: Clinical reports indicate poor outcomes for avulsion injuries, compared with more peripheral nerve damage. These two different injuries may both affect gene expression in spinal neurons, and the changes in gene expression may be related to the types of injuries. METHODS: The brachial plexus of 48 adult male rats was lesioned by either root avulsion close to the spinal cord or distal nerve transection. The rats were quickly revived and remained awake until death at 30, 60, or 120 min after surgery. In rats with avulsive injuries, traumatic sites on the dorsal and ventral horns of the spinal cord were microscopically detected. Immunocytochemical analysis of the c-fos product was performed for the two experimental groups and for sham-treated control animals at the same survival times. RESULTS: An increase in Fos-like immunoreactivity (FLI) in cells of the spinal cord, at levels C4-T1, was detected at 30 min after nerve transection or root avulsion. The number of FLI-positive cells continued to increase at 60 and 120 min after the nerve injury (P=0.001). FLI-positive cells were compared at the C7 level, in laminae 1 and 2, 3 and 4, and 5 to 10, after the two injuries and were found to be more abundant after the avulsive injury (P=0.0001); furthermore, the number of FLI-positive cells increased with time (P=0.001). In a comparison of all levels, both experimental groups demonstrated significantly greater numbers of FLI-positive cells than did controls, and the group with nerve root avulsion showed significantly (P=0.0001) more FLI-positive cells than did the group with distal nerve transection. CONCLUSION: These results suggest that nerve root avulsion from the spinal cord leads to increased and prolonged expression of c-fos and, potentially, greatly increased transcription of new messages for recovery, survival, or cell death.

Animals↗
PubMed1997

PMMA model of steep central islands induced by excimer laser photorefractive keratectomy.

We designed a polymethyl methacrylate (PMMA) model of refractive steep central islands (CIs) induced by PRK. A standardized photorefractive ablation procedure was performed using seven different excimer lasers on test PMMA specimens including 70 flat plates and 98 convex contact lenses. The resulting surface was analyzed by high-resolution confocal microscopy and computerized videokeratoscopy using both TMS-1 and CAS-2000 systems. A total of 50 (54.9%) CIs were observed using computerized videokeratoscopy. The rate of occurrence of CIs was significantly reduced by shock wave absorption (P = 0.0001), aspiration of fumes (P = 0.0044), and smaller diameter ablation (P = 0.0296). The diameter of the CIIs was significantly increased for broad-beam mode ablation (P = 0.016) and for larger ablation zones, (P = 0.042). The refractive power of CIs was significantly increased in the absence of a shock wave absorption system (P = 0.001). Only 20 (40%) of the CIs detected by the TMS-1 device were identified on CAS-2000 at a 0.5 diopter (D) scale resolution level. Shock wave induced deformation and subsequent dynamic alteration of convection forces applied to emitted particles may be the primary mechanism underlying the formation of CIs after PRK, regardless of any biological response of the ablated tissue. Reported rates and characteristics of CIs may largely depend upon the specific design of videokeratoscopes.

Astigmatism↗
PubMed1997

Corneal thickness measurements with the Orbscan Topography System and ultrasonic pachymetry.

PURPOSE: To compare corneal thickness measurements obtained with a new instrument, the Orbscan Topography System, with those obtained with the DGH ultrasonic pachymeter and to assess the agreement and repeatability of the two devices. SETTING: LSU Eye Center, New Orleans, Louisiana, USA. METHODS: Measurement agreement was assessed in 51 eyes of 26 normal volunteers using both Orbscan and ultrasonic pachymetry. Repeatability for the instruments was measured in 10 eyes of 5 additional volunteers. Corneal thicknesses were compared using the analysis of variance (ANOVA). The relationship between the devices was assessed by analysis of regression (ANOR). RESULTS: In the measurement agreement experiment, the mean corneal thickness was 571.3 microm +/- 6.21 SEM with the Orbscan system and 543.3 +/- 7.49 microm with ultrasonic pachymetry; these values were significantly different (F test, ANOVA, P = .0048). In the repeatability experiment, the mean thickness was 561.1 +/- 8.42 microm with the Orbscan system and 537.4 +/- 5.84 microm with ultrasound pachymetry; these values were also significantly different (F test, ANOVA, P = .0003). Analysis of regression showed a significant linear regression between the values obtained with the devices (P = .0001, F test, ANOR). CONCLUSIONS: In both studies, the Orbscan system obtained statistically significantly different and higher values for corneal thickness. Regression analysis suggests that over the range of values in this study, the two devices differ by a constant amount (intercept and slope). The nonzero intercept of this regression shows that the values from the devices differ and cannot be directly substituted for each other. We therefore conclude that in this study, Orbscan system measurements of corneal thickness were 23 to 28 microm greater than ultrasonic pachymeter measurements. Linear regression equations may be developed for the results of measurements from the two devices and used as a precise transformation factor for the values obtained with the two devices.

Adult↗
PubMed1997

A 437-base-pair deletion at the beginning of the latency-associated transcript promoter significantly reduced adrenergically induced herpes simplex virus type 1 ocular reactivation in latently infected rabbits.

In this study we used a herpes simplex virus type 1 (HSV-1) deletion mutant to identify a segment of the genome necessary for epinephrine-induced reactivation in the rabbit eye model of herpetic recurrent disease. In HSV-1 latently infected neural tissue, the only abundant viral products are the latency-associated transcripts (LATs). At least one promoter of LAT has been identified, and mutations in the LAT domain have been used to investigate HSV-1 reactivation. We used an ocular rabbit model of epinephrine-induced HSV-1 reactivation to study the effects of deleting a 437-bp region beginning 796 bp upstream of the LAT CAP site. Specifically, the 437-bp deletion is located between genomic positions 118006 and 118443 of the parent 17Syn+, and the construct is designated 17 delta S/N. This region also controls a portion of the genome encoding two transcripts (1.1 and 1.8 kb) from the LAT domain. A rescuant, 17 delta S/N-Res, was constructed from 17 delta S/N. Following ocular infection, all three viruses produced similar acute dendritic lesions in rabbits. Five weeks after infection, rabbits received transcorneal iontophoresis of epinephrine. The parent, 17Syn+, and the rescuant, 17 delta S/N-Res, underwent a high frequency of HSV-1 ocular reactivation as determined by recovery of infectious virus in the tear film. Rabbits infected with 17 delta S/N had a significantly lower frequency of ocular reactivation. Analysis of the trigeminal ganglia from all three groups of latently infected rabbits revealed (i) similar amounts of HSV DNA (genomic equivalents), (ii) accumulation of 2.0- and 1.45-kb LATs, and (iii) explant reactivation at the same high frequency. Therefore, these studies indicate that the 437-bp deleted region in 17 delta S/N is essential for epinephrine-induced reactivation and could implicate the 1.1- and 1.8-kb transcripts in the mechanisms controlling HSV-1 reactivation.

Adrenergic Agonists↗
PubMed1997

Nerve growth factor antibody stimulates reactivation of ocular herpes simplex virus type 1 in latently infected rabbits.

Anti-nerve growth factor (anti-NGF) antibody has been shown to induce reactivation of latent herpes simplex virus type 1 (HSV-1) in vitro. We found that systemically administered anti-NGF induces ocular shedding of HSV-1 in vivo in rabbits harboring latent virus. Rabbits in which HSV-1 latency had been established were given intravenous injections of goat anti-NGF serum daily for 10 days beginning 42 days after primary viral infection. Tears were assayed for virus for 12 days beginning on the day of the first injection. All eight rabbits given high titer anti-NGF had infectious virus in their tears at least once during the 12-day period. Fifteen of 16 eyes were positive and the average duration of viral shedding for these eyes was 4.0 days. Latently infected rabbits receiving daily injections of nonimmune goat serum or saline for 10 consecutive days were controls. Only six of the 16 (38%) eyes from rabbits receiving nonimmune goat serum shed virus. Only one of 12 eyes from untreated rabbits shed virus. Sera from control rabbits had no detectable anti-NGF activity; titers in anti-NGF-treated rabbits ranged between 1:1000 and 1:10,000. NGF deprivation may act as a neuronal stressor and may share a common second messenger pathway with heat- or cold-stress induced reactivation of latent HSV-1.

Animals↗
PubMed1997

Growth factor and neurotrophic factor mRNA in human lacrimal gland.

PURPOSE: This study examined the expression of important growth factor and receptor messenger RNA (mRNA) in human lacrimal gland. METHOD: Lacrimal gland tissue was obtained from six women, aged 31-85 years, who were undergoing surgery. The specimens were frozen immediately in liquid nitrogen. Total cellular RNA was collected by cesium chloride centrifugation, and the integrity of the RNA was analyzed by gel electrophoresis and spectrophotometry. For the reverse-transcription polymerase chain reaction (RT-PCR) procedure, 1 microgram of total cellular RNA was used for the first strand synthesis and amplified in separate reactions for 34 cycles by using primers specific for transforming growth factor-beta 1, -beta 2, and -beta 3 (TGF beta 1, TGF beta 2, TGF beta 3), TGF beta 3 receptor (TGF beta 3R), basic fibroblast growth factor (bFGF), fibroblast growth factor receptor-1 (FGF-R1), nerve growth factor (beta-NGF), low-affinity NGF receptor (p75NGF-R), and platelet-derived growth factor-AA (PDGF-AA; two of the six cases) and -BB (PDGF-BB; three of the six cases). Product identity was confirmed by restriction endonuclease digestion, by the "hot blot" technique, by DNA sequencing, or by a combination of these. RESULTS: All the lacrimal gland specimens were positive for all growth factors, neurotrophic factors, and receptors except for two specimens that were negative for bFGF. The patients from whom the bFGF-negative specimens were obtained were 68 and 74 years old, and both were identified as having dry eyes-one severe and the other moderate, respectively. These specimens were also analyzed for PDGF-AA and PDGF-BB mRNA, and both were positive. CONCLUSIONS: This study demonstrates that RT-PCR is a rapid and sensitive method for analyzing rare mRNA transcripts in small amounts of tissue. The results suggest that these growth and neurotrophic factors may have autocrine and paracrine roles in modulating the lacrimal gland, and their absence may play a role in pathologic states such as fibrosis and dry eyes.

Adult↗
PubMed1996

Effect of 9-(4-hydroxybutyl)-N2-phenylguanine (HBPG), a thymidine kinase inhibitor, on clinical recurrences of ocular herpetic keratitis in squirrel monkeys.

9-(4-Hydroxybutyl)-N2-phenylguanine (HBPG) is a new viral thymidine kinase inhibitor that we tested for the ability to prevent recurrences of herpetic keratitis. Eighteen squirrel monkeys (Saimiri scuireus) were infected in both corneas with the Rodanus strain of herpes simplex virus type 1 (HSV-1). All corneas showed typical dendritic keratitis 3 days after infection, followed by spontaneous healing. On day 21, the monkeys were randomized into two coded groups and ocular examinations were begun. One group received intraperitoneal (i.p.) injections of HBPG, 150 mg/kg, in a corn oil suspension every 8 h, and the other group received i.p. injections of the corn oil vehicle only. On day 22, recurrences were induced by reducing the temperature of the room in the late afternoon so that a low of 18 degrees C was achieved during the night. After the morning treatment, room temperature was raised to the normal ambient temperature (24-27 degrees C), and treatment was discontinued. Treatment was reinstituted on day 27, the room temperature was lowered again on day 28, and treatment was again discontinued as before. Third and fourth cycles of treatment and cold stress were begun on days 34 and 69. Ocular examinations were continued until day 73, at which point the code was broken. We found that the HBPG treatment significantly reduced the number of corneas with recurrences during the treatment periods, compared with recurrences in untreated, cold-stressed animals (P = 0.01).

Animals↗
PubMed1996

Quantitation of herpes simplex virus type 1 DNA and latency-associated transcripts in rabbit trigeminal ganglia demonstrates a stable reservoir of viral nucleic acids during latency.

In this investigation we determined the dynamics of herpes simplex virus type 1 (HSV-1) DNA and latency-associated transcripts (LAT) in the latently infected rabbit trigeminal ganglion. Rabbit eyes were infected with either the McKrae strain or the l7Syn+ strain of HSV-1. Rabbits were sacrificed between 5 and 360 days after infection and their trigeminal ganglia were analyzed for the number of HSV DNA genomes and the number of neuronal cells expressing LAT. There was no statistically significant change in the number of HSV genomes or the number of neuronal cells expressing LAT in these ganglia between 20 and 360 days after infection. For both strains, the amount of HSV DNA averaged 16.8 genomes per 100 cells, and 9.2% of the neurons expressed LAT. There were 17 to 34 HSV genomes per LAT-expressing neuronal cell. The number of LAT-expressing neurons did not change over the 360 days. Spontaneous reactivation (HSV-1 recovery in tear film) and recurrence (HSV-1-specific epithelial lesions) occurred during the period of this study; however, these events did not alter the quantity of HSV-1 DNA or the number of LAT-expressing cells. These results suggest that after the latent infection is established, the viral DNA in the ganglia does not replicate to any measurable extent over long periods of latency, since no significant change in the number of HSV genomes occurs. The results also suggest that only a very small number of latently infected neuronal cells are needed to produce infectious HSV-1 during reactivation.

Actins↗
PubMed1996

Propranolol suppression of ocular HSV-1 recurrence and associated corneal lesions following spontaneous reactivation in the rabbit.

PURPOSE: Hyperthermia has been shown to induce HSV-1 ocular shedding in mice. Systemic administration of propranolol significantly reduced the recovery of infectious virus in the tears, cornea, and trigeminal ganglia of mice subjected to hyperthermia. The present study was performed to determine the effects of systemic propranolol on ocular shedding and recurrent corneal epithelial lesions in the rabbit model. METHODS: New Zealand white rabbits were infected with HSV-1 strain McKrae or 17Syn+. After latency was established, the animals were treated with systemic propranolol or saline (control) and examined by slit lamp biomicroscopy for corneal lesion. Tear film swabs were cultured to determine the frequency and duration of viral shedding. RESULTS: Propranolol caused a significant reduction in the frequency and duration of ocular HSV-1 shedding and a reduction in the frequency of recurrent corneal epithelia disease, compared with saline treatment. CONCLUSIONS: These results suggest that beta-adrenergic receptor blockers such as propranolol could be useful in suppressing HSV-1 ocular recurrences and corneal disease.

Adrenergic beta-Antagonists↗
PubMed1996

Transient corneal stromal and endothelial changes following soft contact lens wear: a study with confocal microscopy.

PURPOSE: Previous studies have described transient corneal endothelial changes in non-contact lens wearers after a short period of soft contact lens wear by means of contact and noncontact specular microscopy and modified slit lamp biomicroscopy, which provide magnifications from 60 to 100x. In this investigation, we documented and characterized these contact lens-related corneal changes using the white light, real-time confocal microscope, which is capable of cellular resolution imaging of all layers within the cornea at magnifications of 100 to 500x. METHODS: We used a clinical confocal microscope to study corneal changes in three patients wearing a high water content soft contact lens for the first time. RESULTS: In one patient, endothelial changes consisting of irregularly shaped, round or oval, dark regions were observed within the endothelial mosaic. Scattered hyper-reflective keratocyte nuclei were seen in the posterior stroma. The keratocytic and endothelial changes were most evident 20 minutes after placement of the lens. By 30 minutes, the changes were fewer and less prominent, and the brightness of the highly reflective keratocyte nuclei had decreased. CONCLUSIONS: These studies show, for the first time, that the transient changes associated with contact lens wear occur not only in the endothelium, but also in the corneal stroma. It has been suggested that the changes result from an increase in CO2 and lactic acid, which causes a transient reduction in the corneal pH. We hypothesize that the resulting acidic environment may induce gene expression that causes changes in the involved nuclei, which in the keratocytes become hyper-reflective, and in the endothelium become enlarged, resulting in posterior displacement of the cell membrane and producing the dark "blebs" and irregular lines observed at this level of the posterior cornea.

Contact Lenses, Hydrophilic↗
PubMed1995

Landing from a jump: the role of vision when landing from known and unknown heights.

This study investigated the modulation of prelanding muscle activity with normal or perturbed vision under conditions where jump height was known or unknown. Lower leg electromyography (EMG) was monitored while subjects jumped from a constant (0.45 m) or variable (0.35-0.55 m) heights when vision was unaltered or perturbed by a strobe light, blackened goggles or a visual conflict dome. Results indicated that visual perturbations had a global effect on muscle onsets only when height was randomized. Randomization rather than jump height also affected the onset patterns observed for normal vision jumps. It is suggested that strategies for triggering prelanding EMG are mutable and may depend on availability of sensory modalities and impact force estimation as well as on vision.

Adult↗
PubMed1995

Autologous blood transfusion in the pediatric patient.

The use of autologous blood has been encouraged by blood banks and transfusion services for the past 10 years, mainly because of public concern over the safety of blood. The virtues include reduced likelihood of reactions to transfused blood and reduction or elimination of the risk of alloimmunization and transfusion transmitted diseases such as hepatitis C and the human immunodeficiency virus. The pediatric patient population has been largely excluded from published series on autologous blood usage. In this article, the literature on the use of autologous blood in pediatric patients is reviewed, and some considerations for collecting autologous blood from smaller patients are addressed, including the volume of blood to collect from smaller patients. Based on the experience reported in the literature, patients as young as 6 years of age may be candidates for autologous blood donation before a scheduled surgical procedure. Other methods to provide autologous blood for pediatric patients are discussed, including intraoperative hemodilution and intraoperative and postoperative blood salvage. By considering all the potential options available to pediatric patients, the likelihood of requiring transfusion of allogeneic blood can be reduced, along with the associated risks.

Adolescent↗
PubMed1995

Early changes in optic disc compliance and surface position in experimental glaucoma.

PURPOSE: To detect changes in the compliance and baseline position (position at the baseline time point of a compliance test) of the monkey optic disc after the onset of chronic experimental glaucoma. METHODS: Sixty-six compliance tests were performed on 26 eyes of 13 monkeys. Longitudinal Study. In seven normal monkeys, compliance tests were performed three times in one eye (study eye) and once in the contralateral eye. In the study eye of five of these monkeys, chronic experimental glaucoma was then induced and compliance tests were performed at some or all of the following postglaucoma testing intervals: 1 to 2 weeks, 3 to 4 weeks, 5 to 8 weeks, 9 to 12 weeks, 13 to 18 weeks, and more than 18 weeks after the onset of elevated intraocular pressure (IOP). In the study eye of the remaining two monkeys, the optic nerve was transected, and compliance was tested at 5, 9, and 13 weeks after transection. An analysis of variance (ANOVA) was performed to detect an increase (hypercompliance) or decrease (rigidity) in the compliance of the glaucomatous eyes at each testing interval. A second ANOVA was performed to detect the onset of chronic posterior deformation of the baseline position of each disc. Cross-Sectional Study. In six additional monkeys with pre-existing experimental glaucoma, the glaucomatous study eye was compliance tested at one of the postglaucoma testing intervals used in the longitudinal study. The contralateral normal eye was compliance tested once. These data were then added to the data from the five longitudinally studied monkeys at the appropriate preglaucoma and postglaucoma testing intervals. A third ANOVA was done to compare the compliance of the expanded group of glaucomatous eyes at each postintervention testing interval with the compliance of the 13 normal contralateral eyes. RESULTS: Compliance. In the longitudinally (Pr > F = 0.0005) and cross-sectionally (Pr > F = 0.0001) studied glaucomatous eyes, optic disc compliance increased significantly by 1 to 2 weeks and then returned to a level statistically indistinguishable from normal within 13 to 18 weeks after the onset of glaucoma. In the transection eyes, the optic discs were significantly less compliant (more rigid) at 5 and 9 weeks after transection compared with the discs in either the normal or the glaucomatous eyes (Pr > F < 0.05). Baseline Optic Disc Position. Chronic posterior deformation of the disc was detected in one of three eyes tested 1 to 2 weeks and three of four eyes tested 3 to 4 weeks after the onset of glaucoma (Pr > F < 0.05). Chronic posterior deformation was not detected in the discs of either of the transection eyes at any of the post-transection testing intervals. CONCLUSION: Changes in optic disc compliance and surface position were detected by digitized image analysis within 2 to 4 weeks of the onset of experimental glaucoma in the monkey eye. These findings are unlikely to be due to axon loss alone, because they did not occur in optic nerve transection eyes (which constitute a model of axon loss in which intraocular pressures remain normal). The results suggest that IOP-related damage to the load-bearing connective tissues of the optic nerve head may occur early in the course of experimental glaucoma.

Analysis of Variance↗
PubMed1995

Measurement of optic disc compliance by digitized image analysis in the normal monkey eye.

PURPOSE: To characterize the compliance of the normal monkey optic disc under conditions of induced short-term fluctuations in intraocular pressure (IOP). METHODS: In 10 monkeys, one eye was compliance tested on three separate days followed by a single test of the contralateral eye (40 compliance tests). In a testing session, the optic disc was imaged at 2 and 47 minutes (baseline time point) after IOP was lowered to 10 mmHg; then at 2, 17, 32, and 47 minutes after IOP was elevated to 45 mmHg; then at 2, 47, and, in some cases, 92 minutes after IOP was lowered back to 10 mmHg. Eight digitized images were analyzed at each time point, yielding two parameters to characterize the position of the disc: the Mean Position of the Disc (MPD) and the Change from MPDBaseline (the value of MPD at a given time point minus the value for MPD at the baseline time point of that testing session). Analysis of variance (ANOVA) testing was used to evaluate the overall effect of IOP on both parameters while taking into account the effects of variability due to different monkeys and repetitions of the test as well as differences between the two eyes of an individual monkey. With the addition of data from 11 compliance tests performed on eight additional monkeys, the overall results were calculated in terms of the mean Change from MPDBaseline at each time point for a total of 51 compliance testing sessions. RESULTS: The mean Change from MPDBaseline was -28 microns (95% confidence interval, -23 to -33 microns) 47 minutes after elevation of IOP. The disc surface returned to its baseline position 92 minutes after IOP was lowered back to 10 mmHg. Elevation of IOP within a compliance test had a significant effect on the position of the optic disc surface (P = 0.0002, ANOVA), as characterized by the parameter Change from MPDBaseline. Neither the difference in the amount of movement between the two eyes of an individual monkey nor the variability within the three repetitions of the test in a given eye was statistically significant. CONCLUSION: Small, reversible (elastic) posterior deformations of the optic disc surface follow acute elevations of IOP in the normal monkey eye. Detection of acute IOP-induced deformations of the optic disc surface may represent a means by which to mechanically test the deeper load-bearing tissues of the optic nerve head.

Analysis of Variance↗
PubMed1995

Cell cycle kinetics in pterygium at three latitudes.

The cell cycle kinetics of 93 specimens of pterygial tissue, as well as 19 specimens of normal conjunctiva, from patients at three sites representing three different latitudes (Singapore, 1 degree; Hong Kong, 22 degrees; and Little Rock, Arkansas, 34 degrees) were evaluated by flow cytometry. The results showed no difference in cellular proliferation patterns between pterygial and conjunctival tissue at any of the sites, suggesting that pterygium is not a disorder of excess cellular proliferation. Transmission electron microscopy showed extracellular matrix to be a prominent component of pterygium. Cellular proliferation patterns of primary and recurrent pterygium were not significantly different from each other. Factors associated with increased incidence of pterygium included male sex, outdoor occupation, and advanced age.

Adult↗