Factors affecting image acquisition during scanning laser polarimetry.
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Artifacts↗
Biomedical subjects
G Holló
Publications and source records attributed to G Holló.
Increase of endothelin-1 concentration in aqueous humour induced by argon laser trabeculoplasty in the rabbit. A preliminary study.
PURPOSE: To investigate the impact of argon laser trabeculoplasty (ALT) on endothelin-1 (ET-1) concentration of aqueous humour and intraocular pressure (IOP) in the rabbit. METHODS: Standard ALT was performed on one eye of 19 pigmented rabbits. A modified treatment in which the laser light was focused on the inner limbal surface (argon laser scleroplasty, ALS) was also performed on one eye of a further 15 rabbits. IOP was measured with a Tono-Pen-2 tonometer before treatment, under general anaesthesia. Post-laser IOP measurements followed by aqueous humour aspiration were performed under general anaesthesia 4, 24 and 120 hours after treatment. IOP readings were considered relative values, since the tonometer was calibrated to the human eye and not to the rabbit eyeball. Different groups of animals were used for the tests after each time period. The groups of 4 hours time consisted of 9 animals which had undergone ALT and 5 which had undergone ALS. All the other groups consisted of 5 animals each. RESULTS: In the ALT group IOP decreased following treatment, and the IOP change (a relative change) showed a significant difference between the treated and the control eyes at all three follow-up times (paired t-test, p<0.05), and a significant interaction was found between treatment and follow-up time (ANOVA, p<0.05). Concentration of ET-1 in the aqueous humour of the treated eyes increased by about an order of magnitude 4 hours after ALT, compared to the contralateral control eyes (103.66+/-41.59 pg/ml versus 8.75+/-2.95 pg/ml, Wilcoxon matched pairs test, p<0.01). ET-1 concentration 24 and 120 hours after ALT, however, did not differ significantly from the corresponding contralateral control values. In the ALS group neither IOP change nor aqueous humour ET-1 concentration differed in a statistically significant manner between the treated and control eyes. CONCLUSIONS: The results suggest that ALT is followed by an immediate and short-term increase of aqueous humour ET-1 concentration in the rabbit, probably due to leakage from the uveal tissue.
Animals↗
Peripapillary circle of Zinn-Haller revealed by fundus fluorescein angiography.
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Fluorescein Angiography↗
Cold pressor test and plasma endothelin-1 concentration in primary open-angle and capsular glaucoma.
PURPOSE: The authors investigate cutaneous capillary blood flow using the cold pressor test and plasma endothelin-1 (ET-1) concentration in primary open-angle glaucoma (POAG) and capsular glaucoma (CG), and evaluate the connection between the two factors, which reflect vasoconstrictive mechanisms with a potential role in the pathogenesis of glaucoma. METHODS: The ET-1 concentration of venous blood plasma samples from 20 patients with POAG, 22 patients with CG, and 44 healthy volunteers was measured using a radioimmunoassay kit. On a separate occasion, the right hand was subjected to the cold pressor test (hand immersed in 4 degrees C water for 30 seconds, then in 30 degrees C water for 2 minutes), during which cutaneous capillary blood flow of the left middle finger was measured using a Periflux 4001 Master Laser Doppler Flowmeter (Perimed AB, Järfälla, Sweden). RESULTS: In the CG group, baseline cutaneous capillary blood flow was significantly lower than either that of POAG (p = 0.001) or that of the healthy group (p = 0.046). In the CG group, time to maximal cold-induced flow reduction was significantly longer than in the POAG group (p = 0.028) or in the healthy group (p = 0.025). Also, recovery time was significantly longer in CG than in the healthy group (p = 0.008) and tended to be longer than in the POAG group. No statistically significant difference between the groups was found either in the frequency of increased vasospastic response (cold-induced flow reduction higher than 70% of the baseline value) or in ET-1 concentration. No correlation was seen between ET-1 concentration and the findings of the cold pressor test. CONCLUSION: The results suggest that in CG, which is a systemic disease with vascular abnormalities, baseline cutaneous capillary perfusion and its response to cold and warmth are altered, without any alteration of plasma ET-1 level. The authors found that both plasma ET-1 level and the response to the cold pressor test are normal in patients with POAG. These findings suggest that regulation of cutaneous capillary perfusion and the concentration of plasma ET-1 are not related to each other in patients with glaucoma.
Biomarkers↗
Scanning laser Doppler flowmeter study of retinal and optic disk blood flow in glaucomatous patients.
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Blood Flow Velocity↗
Scanning laser polarimetry of the retinal nerve fibre layer in primary open angle and capsular glaucoma.
AIMS: To evaluate the clinical value of scanning laser polarimetry with the nerve fibre analyser type II in primary open angle glaucoma (POAG) and capsular glaucoma. METHODS: Scanning laser polarimetry was performed on one eye of 30 patients suffering from POAG, 25 patients suffering from capsular glaucoma, and on 35 healthy control subjects. The retinal nerve fibre layer (RNFL) thickness values were compared among the groups. Reproducibility of the measurements was calculated and the influence of pilocarpine induced miosis on the results was investigated. RESULTS: RNFL thickness in the superior and inferior sectors, as well as along the total circumference was significantly lower in both glaucoma groups than in the control eyes (p < 0.05). None of the thickness values differed between the two glaucoma groups. Reproducibility was comparable in all groups; the coefficient of variation varied between 3.0% and 8.9% for the different sectors investigated. Miosis had no significant impact either on the thickness values or on the reproducibility (p > 0.05). CONCLUSION: The results suggest that scanning laser polarimetry is a useful method for nerve fibre layer analysis in glaucoma, and that it is not influenced by the pupil size.
Aged↗
Scanning laser polarimetry in corneal haze after excimer laser refractive surgery.
PURPOSE: We evaluate the technique of retinal nerve fiber layer thickness measurement using scanning laser polarimetry in cases of central corneal haze due to photorefractive keratectomy. METHODS: Nerve fiber layer thickness was measured using a Nerve Fiber Analyzer II (Laser Diagnostic Technologies, Inc., San Diego, CA, U.S.A.) in eight eyes of eight individuals with mild to pronounced corneal haze owing to earlier excimer laser refractive surgery, and in nine eyes of nine control volunteers. RESULTS: Neither total and sectorial nerve fiber layer thickness values, nor superior/ inferior quadrant thickness ratio differed in a statistically significant manner between the two groups (unpaired t test, p > 0.05). Reproducibility in the "haze" and control groups was 4.3% and 3.4%, respectively, for mean nerve fiber layer thickness calculated from all quadrants around the disc. The figures were 4.9% and 5.2%, respectively, for the superior quadrant thickness; 8.2% and 8.8%, respectively, for the temporal thickness values; 5.4% and 4.6%, respectively, for the inferior thickness values; and 4.1% and 5.0%, respectively, for the nasal quadrant thickness values. For the superior/inferior quadrant thickness ratio the reproducibility was 4.4% and 6.8%, respectively. None of the corresponding values for reproducibility differed significantly between the two groups (F-test, p > 0.05). CONCLUSIONS: Corneal haze did not cause an artificial increase of the thickness values measured with scanning laser polarimetry and did not diminish the reproducibility of the measurement. The results suggest that scanning laser polarimetry may be a suitable method for the precise measurement of the nerve fiber layer thickness even in eyes with persistent corneal haze after excimer laser refractive surgery.
Adult↗
De novo chromosome formations by large-scale amplification of the centromeric region of mouse chromosomes.
Chromosomes formed de novo which originated from the centromeric region of mouse chromosome 7, have been analysed. These new chromosomes were formed by apparently similar large-scale amplification processes, and are organized into amplicons of approximately 30 Mb. Centromeric satellite DNA was found to be the constant component of all amplicons. Satellite DNA sequences either bordered the large euchromatic amplicons (E-type amplification), or made up the bulk of the constitutive heterochromatic amplicons (H-type amplification). Detailed analysis of a heterochromatic megachromosome formed de novo by an H-type amplification revealed that it is composed of a tandem array of 10-12 large (approximately 30 Mb) amplicons each marked with integrated "foreign' DNA sequences at both ends. Each amplicon is a giant palindrome, consisting of two inverted doublets of approximately 7.5-Mb blocks of satellite DNA. Our results indicate that the building units of the pericentric heterochromatin of mouse chromosomes are approximately 7.5-Mb blocks of satellite DNA flanked by non-satellite sequences. We suggest that the formation de novo of various chromosome segments and chromosomes seen in different cell lines may be the result of large-scale E- and H-type amplification initiated in the pericentric region of chromosomes.
Animals↗
Evidence for a megareplicon covering megabases of centromeric chromosome segments.
We have analysed the replication of the heterochromatic megachromosome that was formed de novo by a large-scale amplification process initiated in the centromeric region of mouse chromosome 7. The megachromosome is organized into amplicons approximately 30 Mb in size, and each amplicon consists of two large inverted repeats delimited by a primary replication initiation site. Our results suggest that these segments represent a higher order replication unit (megareplicon) of the centromeric region of mouse chromosomes. Analysis of the replication of the megareplicons indicates that the pericentric heterochromatin and the centromere of mouse chromosomes begin to replicate early, and that their replication continues through approximately three-quarters of the S-phase. We suggest that a replication-directed mechanism may account for the initiation of large-scale amplification in the centromeric regions of mouse chromosomes, and may also explain the formation of new, stable chromosome segments and chromosomes.
Animals↗
Argon and low energy, pulsed Nd:YAG laser trabeculoplasty. A prospective, comparative clinical and morphological study.
Argon laser trabeculoplasty (ALT; 1.0 W, 0.1 sec, 50 microns) was performed in right eyes, and low energy, Q-switched Nd:YAG laser trabeculoplasty (Nd:YAGLT; 1.1-4.8 mJ/pulse) in left eyes of 14 patients with primary open-angle glaucoma and in one patient with juvenile glaucoma. The pre-laser intraocular pressure (IOP) was medically uncontrollable (IOP > 21 mmHg). The interocular pressure difference varied between 0 and 3 mmHg. In 9 patients IOP decreased to less than 22 mmHg (success) in both eyes. No statistically significant difference has been revealed with paired t-test in the degree of IOP decrease between ALT and Nd:YAGLT treated eyes during the 1-18 months' follow-up. Treatment variables of Nd:YAGLT had no statistically significant effect on the duration of the post-laser success with Cox-regression. In 4 patients both treatments were ineffective (IOP > 21 mmHg). In 2 patients ALT was successful but Nd:YAGLT was ineffective. In three cases of early bilateral laser failure (IOP > 21 mmHg at the first month visit) trabeculectomy was performed on both eyes in the third post-laser month. Following ALT the uveoscleral meshwork was severely destroyed in the area of the laser spots, and the surrounding collagen fibres were heat-damaged. The meshwork between the laser spots was covered by a membrane formed by migrating endothelial cells. In the uveoscleral meshwork Nd:YAGLT induced severe focal damage surrounded by circumscript shrinkage and scarring. The juxtacanalicular tissue remained free of laser induced damage. No endothelial membrane was present. The results suggest that low energy, Q-switched Nd:YAGLT may represent an alternative method of glaucoma laser surgery.
Adult↗
Comment on the paper of Doctors Rouhiainen, Leino and Teräsvirta.
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Drug Therapy↗
Retinopathy of pancreatitis indicates multiple-organ failure and poor prognosis in severe acute pancreatitis.
During hospitalization for severe acute necrotizing pancreatitis, a connection between the onset of retinopathy of pancreatitis and multiple-organ failure was studied. Ophthalmoscopy was repeated every second day and continuous staging for multiple-organ failure was performed in 38 patients. Typical retinopathy of pancreatitis developed in 7 of 10 patients with multiple-organ failure and only in 4 of the 28 patients without multiple-organ failure. Retinopathy of pancreatitis was observed in 7 of the 18 cases leading to lethal outcome and only in 4 of the 20 surviving patients. No correlation was observed between the development of retinopathy of pancreatitis and hemodialysis, pre-existing diabetes mellitus, abnormal platelet count, result of hemoculture, c reactive protein value, fraction of inspired oxygen and adult respiratory distress syndrome. In the 21 control patients in grave general state but without acute pancreatitis, retinopathy of pancreatitis was never observed. In our prospective study the onset of retinopathy of pancreatitis had clinical prognostic value and indicated multiple-organ failure and poor prognosis in severe acute necrotizing pancreatitis.
Acute Disease↗
The effect of brief intrascleral or episcleral application of mitomycin C on the ciliary epithelium and pressure in the rabbit eye.
Ten albino rabbits underwent bilateral Cairns' trabeculectomy (group 1). A sponge soaked with 0.5 mg/ml mitomycin C solution was applied under the scleral flap for 5 min followed by irrigation with 20 ml 0.9% sodium chloride solution in the left eyes. In the right eyes a sponge soaked with 0.9% sodium chloride solutions was applied. In 9 albino rabbits a 3 x 2 mm episcleral area at 12 o'clock position was exposed to 0.5 mg/ml mitomycin C solution on one side and to 0.9% sodium chloride solution in the contralateral eye (group 2). Five, 10 and 30 days (group 1 and 2) and 3 months (group 1) following surgery specimens of the ciliary body adjacent, beside and opposite to the site of the operation were excised and studied with light and electron microscopy. No stromal or epithelial morphological changes of toxic origin have been revealed in the ciliary processes, even in specimens adjacent to the surgical area. In 5 albino rabbits (group 3) intraocular pressure was recorded before surgery and 5, 10 and 30 days after unilateral, episcleral mitomycin C application described in group 2. No significant changes or interocular difference has been recorded. The results suggest that long-term postoperative hypotony following trabeculectomy with mitomycin C is not caused by reduced aqueous humour secretion of toxic origin.
Animals↗
Cytokines in the treatment of malignancies.
Cytokines are pleiotropic peptides produced by lymphoid cells that play important roles in cellular proliferation and multiplication. Diminished or enhanced production or constitutive secretion of cytokines contributes to the aetiology and pathogenesis of several diseases. They are soluble mediators eliciting specific responses of different target cells of paracrine, autocrine and cascade systems of the organism. Their secretion is regulated at the molecular genetic level. Gene rearrangements of cytokines and their receptors have been demonstrated in several diseases. As means of specific or supportive therapy, cytokine treatment has been used both in neoplastic and other proliferative diseases. Lymphokines and interferons comprise the first, whereas colony stimulating factors and growth factors yield the second group of cytokines. Most scientific experience is with interferon-alpha. Its anti-viral mechanism of action has been extensively studied and clarified, whereas its antitumour effect is more obscure and is a result of many simultaneous biologic events.
Cytokines↗
Bilateral intraocular pressure elevation and decrease of facility of aqueous humour outflow as a consequence of regional lymphoedema of head and neck.
Aqueous humour drainage to the deep cervical lymphatics has been proven in animal experiments, but there have been no observations of changes in intraocular pressure (IOP) or aqueous humour drainage as a consequence of lymph drainage dysfunction. The history of a patient with non-Hodgkin's lymphoma, who underwent a left-sided radical neck dissection in January 1991, is reported. From the end of 1991 lymphoedema of the head and neck, predominantly on the right side, developed without venous stasis but with significant bilateral IOP elevation and aqueous humour outflow reduction, refract to conventional treatment. Two days after cytostatic treatment the lymphoedema disappeared, and IOP and aqueous humour outflow became normal. Four days later the patient died because of an acute bronchopneumonia. The pathological examination revealed an intact internal jugular venous system, enlarged lymph nodes and, as a consequence of previous irradiation, cicatrization in the right side of the neck. On the left side, there was absence of the internal jugular vein and jugular lymphatic trunk due to previous radical neck dissection. Our case suggests that regional lymphatic stasis and the absence of the collateral drainage to the contralateral side significantly reduces the aqueous humour outflow and leads to a bilateral, secondary IOP elevation.
Aqueous Humor↗
Clinicopathology of a case with retinopathy of pancreatitis.
Bilateral retinopathy of pancreatitis developed in a 36-year-old male patient during recurrent acute necrotizing pancreatitis. The retinopathy remained clinically unchanged between the detection and the death 6 days later. Characteristics of the retinal lesions were histologically similar to cotton-wool spots of other origin, but all the retinal vessels including vessels around and in the cotton-wool spots were intact and contained plasma and red blood cells. Absence of vascular occlusion and endothelial damage suggests that in acute pancreatitis vascular embolisation in the retina is not necessary to the development of cotton-wool patches.
Acute Disease↗
[Dry eye syndrome in patients with biliary cirrhosis].
Ophthalmic state of 18 women patients between 40 and 69 years of age with primary biliary cirrhosis (PBC) was studied. Tear secretion was studied by Schirmer I., break up time and conjunctival and corneal bengal rose staining tests. In 15 cases serious degree of keratoconjunctivitis sicca has been revealed. Xanthelasma of the lid was found in three patients. Visual functions were intact. Kayser-Fleischer ring was absent in every case. There was no connection between the duration or laboratory characteristics of the PBC and the severity of the keratoconjunctivitis sicca. In nine patients of the cases requiring tear substitution eye drops of methylcellulosum available in Hungary were insufficient. Hydroxypropyl-methylcellulosum drops of eye gel containing peptides of low molecular weight eliminated the symptoms in these cases. The authors emphasize that PBC should be considered as a possible underlying disease in women over 30 years with severe dry eye syndrome.
Adult↗