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Biomedical subjects

L Laroche

Publications and source records attributed to L Laroche.

At least 253 records · Page 14Linked to original sources
PubMed1977

Thymocyte subpopulations in young and adult mice. I. Separation by density gradient and steroid treatment.

Thymocyte subpopulations obtained after centrifugation on Ficoll density gradients have been studied in young and 6-week-old mice. Whereas the totality of the thymocytes appeared theta-positive, gradient fractionation showed the existence of a subpopulation of immunoglobulin and theta-negative lymphocytes among the lightest cells. Similar separation was obtained in both age groups in terms of the distribution of such theta-negative cells as well as of phytomitogen responses. However, cell pools with characteristics of cortical cells were less well represented in 2 to 10-day-old mice than in adult mice, indicating that post-natal thymic development is essentially associated with the appearance of cortical cells. The gradient did not however, provide a clear separation assessed on other parameters such as theta antigen, concanavalin A and phytohemagglutinin responses and steroid sensitivity. Cellular heterogeneity for a given cell density is discussed in relation to the hypothesis of two separate maturation pathways of thymocytes.

Age Factors↗
PubMed1975

[Acanthosis nigricans associated with diffuse esophageal papillomatosis].

Two cases of acanthosis nigricans seen in 2 women, the characteristics of which were those of malignant forms, showed oesophageal involvment, the appearance of which was quite similar to that of the mucosal localisations of the syndrome. The authors discuss the features which distinguish the oesophageal localisation of acanthosis nigricans from other types of oesophageal acanthosis or papillomata. In one case, this type of acanthosis, seven years after its onset, was not associated with any detectable malignant change and in the other the cutaneous lesions were improved following surgery at which the associated gastric tumour was not removed.

Acanthosis Nigricans↗
PubMedDate not supplied

Measurement of irregular astigmatism using semimeridian data from videokeratographs.

BACKGROUND: Irregular astigmatism is one of the most troublesome side effects of corneal surgery. We attempted to quantify irregular astigmatism in a simple way, using semimeridian data from videokeratographs of corneas with different amounts of irregular astigmatism. METHODS: We studied the corneal topography of 30 normal corneas to be used as controls, 30 corneas from patients after radial keratotomy, 30 corneas from patients after nonfreeze myopic keratomileusis, and 30 corneas with clinically apparent keratoconus. We developed two diagnostic formulas, a refractive power symmetry index and an angle symmetry index, using the absolute-scale, color-coded map, and semimeridian data from the EyeSys Corneal Analysis System, and used them to compare the four groups of corneas. RESULTS: In the corneas with irregular astigmatism, values for the refractive power symmetry index and angle symmetry index were significantly higher than in the normal corneas. The refractive power symmetry index confidence interval set at 95% was 0.58 diopters (D) (range 0.00 D to 0.58 D) in the control group. Using these limits, most values in the radial keratotomy, keratomileusis, and keratoconus groups were abnormal. Spectacle-corrected visual acuity correlated negatively with the refractive power symmetry index (rs = -0.58, p < .001). The refractive power symmetry index sensitivity and specificity were respectively 97% and 66%. Spectacle-corrected visual acuity did not correlate with the angle symmetry index. CONCLUSIONS: Semimeridian data from videokeratographs can be used to quantify irregular astigmatism.

Adult↗
PubMedDate not supplied

Videokeratography, keratometry, and refraction after penetrating keratoplasty.

PURPOSE: To identify the correlation between videokeratography, autorefractometry, autokeratometry, and keratometry measurements and the subjective manifest refraction and spectacle-corrected visual acuity after penetrating keratoplasty. METHODS: We studied 100 eyes from 100 patients that had undergone penetrating keratoplasty. All eyes were examined by videokeratography (EyeSys 2000) (axial, tangential, and refractive power maps), autorefractometry, autokeratometry, and keratometry. Measurements were made at an an average of 19 +/- 9 months after surgery. Postoperative refractive astigmatism, spherical equivalent refraction, and spectacle-corrected visual acuity were studied by regression analysis. RESULTS: Both the total topographic cylinder measured by the refractive power map and topographic cylinder measured by the axial power map showed the strongest correlation with the manifest refractive cylinder (rs = +0.89, P < .001). The axis of astigmatism determined by keratometry and autokeratometry showed the strongest correlation with the subjective manifest refraction axis (rs = +0.87, P < .001). The total topographic cylinder showed the strongest correlation with the spectacle-corrected visual acuity (rs = +0.38, P = .001); however the topographic indices of predicted corneal acuity, corneal acuity, corneal uniformity index, asphericity, and refractive power symmetry did not correlate with spectacle-corrected visual acuity. CONCLUSION: Measurement of astigmatism after penetrating keratoplasty can be made more accurate by using videokeratographic measurements to supplement retinoscopic and manifest refraction. Other useful methods for predicting the axis of refractive astigmatism include keratometry, autokeratometry, and autorefractometry. In this study, indices designed to measure corneal surface irregularity failed to predict visual acuity after penetrating keratoplasty.

Astigmatism↗
PubMedDate not supplied

Prediction of spectacle-corrected visual acuity using videokeratography.

PURPOSE: Our aim was to improve prediction of spectacle-corrected visual acuity (SCVA) using indices derived from the EyeSys System 2000 data (version 3.1). METHODS: We studied corneal topography in 182 eyes from 8 groups of patients. Holladay Diagnostic Summary indices were recorded. Nine statistical indices calculated with the first 8-ring data and refractive power symmetry index were also studied. Correlation with SCVA (LogMAR units) was studied by means of Pearson's regression. Multiple linear regression was used to obtain linear equations combining several indices. RESULTS: At a univariate level, total astigmatism cylinder showed the strongest correlation with SCVA (r = .63, P = .0001). At a multivariate level, the predicted visual acuity obtained by linear equation combining the asphericity coefficient, the predicted corneal acuity, the mean of the means, and the total astigmatism cylinder was closely associated with SCVA (r = .72, P = .0001). It was identical to SCVA in 58.2% of the cases, within one line in 75.8%, and within two lines in 91.2%. CONCLUSION: Multiple linear regression resulted in the best prediction of spectacle-corrected visual acuity, giving notable improvement in prediction of spectacle-corrected visual acuity as compared to the predicted corneal acuity available in the EyeSys System 2000.

Astigmatism↗
PubMedDate not supplied

[Use of topical cyclosporin in microcrystalline keratopathy due to Streptococcus].

Infectious crystalline keratopathy is an exceptional but serious complication of penetrating keratoplasty. Streptococcus viridans and a steroid treatment are very often found. The treatment is always lengthy and difficult. The high number of bacteria and the steroid treatment, necessary to prevent rejection, worsen the infection. We report a case of Streptococcus crystalline keratopathy that evolved, despite the treatment, simultaneously toward abscess and acute rejection. Topical cyclosporin treatment was used to maintain an immunosuppression without worsening the infection.

Administration, Topical↗
PubMedDate not supplied

[Micro-endoscopy of the lacrimal apparatus combined with Erbium YAG laser: an anatomical study. New methods of imaging].

PURPOSE: To study the anatomic structure and the endoscopic aspect of the lacrimal drainage system and to evaluate the efficacy of the Erbium laser with microendoscope in lacrimal obstruction. METHODS: Twenty lacrimal ducts from ten fresh cadaver heads were used to lead a special rigid probe of 1.1. mm diameter (Endognost Schwind). This probe combined a flexible endoscopic probe of 500 mu, an Erbium laser fiber of 375 mu and an irrigation. The probe was introduced through the inferior canaliculus. Progressing in the lacrimal system, all the images were analysed. Then, we used the laser fiber to open the lacrimal sac mucosa and the lacrimal bone. RESULTS: The anatomo-endoscopic analysis was performed using endoscopic data. We appreciated essentially the walls of valves and sinuses that appeared only functional when increasing the irrigation flow. The laser could easily open the mucosa and the lacrimal bone but not the maxilla. DISCUSSION: The small size of the cannula allows to use the system for the diagnosis of lacrimal obstructions. The combined laser allows to treat at same time canalicular obstructions and lower obstructions. CONCLUSION: The endocanalicular study of the lacrimal drainage system can diagnose the type of obstruction and can treat it. A clinical study is requested to confirm these results.

Cadaver↗
PubMedDate not supplied

[Autoradiographic localization and characterization of the ocular binding sites of the VIP (vasoactive intestinal peptide) in albino rats and rabbits].

Despite its name, Vasoactive Intestinal Peptide (VIP), a 28-amino acid peptide, is widely distributed in the eye where it is thought to play a physiological role, particularly in aqueous humor dynamics or retinal neurotransmission. Localization and pharmacological properties of VIP binding sites were investigated in eyes from albino rabbit and rat using an in vitro autoradiographic method. 125I-VIP was used as ligand and unlabelled VIP was used to displace labelled VIP. Autoradiograms were generated by apposing the slides to 3H-Ultrofilm or autoradiographic emulsion and analysed using an image analysis system. Specific binding represented about 85% of total binding. Kinetic studies showed that equilibrium was reached after 140 min incubation at room temperature. Biochemical investigations demonstrated that 125I-VIP bound to a population of sites with high affinity (Kd = 2.95 +/- 0.5 nM). Inhibition of 125I-VIP binding with VIP and related peptide gave a rank order of potency: VIP greater than peptide histidine isoleucine greater than secretin greater than human growth hormone-releasing factor, glucagon, VIP1-14, VIP14-28. In both species, specific binding were found in conjunctiva, iris, ciliary processes, choroid and retina. Quantitative analysis of autoradiograms revealed that the highest densities of binding sites were localized in the ciliary epithelium in rabbits and in the inner retina in rats.

Animals↗
PubMedDate not supplied

[Alloplastic keratophakia. Use of a new polymer].

Alloplastic keratophakia has been performed with a new hydrogel, never used in Ophthalmology (poly-anionical material). Physical and chemical properties are evaluated. In vitro and in vivo studies disclosed a very good biocompatibility.

Animals↗
PubMedDate not supplied

[Atypical tapetoretinal degeneration simulating a neurologic syndrome].

We report the case of a 57-year-old woman with progressive bilateral visual acuity loss, presumed during ten years to be secondary to a neurological disease. Ophthalmological examination showed for both eyes pallor of the optic discs and arteriolar narrowing. Periphery was normal, without pigment clumping. Fluorescein angiography showed a widespread irregular hypopigmentation and discovered a bilateral macular edema. Abnormal rod function was confirmed by electroretinography. A review of the literature data shows the variety of clinical symptoms in patients with retinitis pigmentosa and the frequency of atypical non-pigmented forms. Those forms are usually considered as early stages of the disease. Besides, macular lesions, and macular edema in particular, are frequently reported.

Diagnosis, Differential↗
PubMedDate not supplied

Inhibition of antiskin allograft immunity induced by infusions with photoinactivated effector T lymphocytes (PET cells).

Induction of tolerance for skin allotransplantation requires selective suppression of the host response to foreign histocompatibility antigens. This report describes a new approach which employs pre-treatment with 8-methoxypsoralen (8-MOP) and ultraviolet A light (UVA) to render the effector cells of graft rejection immunogenic for the syngeneic recipient. Eight days after BALB/c mice received CBA/j skin grafts, their splenocytes were treated with 100 ng/ml 8-MOP and 1 J/cm2 UVA prior to reinfusion into naive BALB/c recipients. Recipient mice were tested for tolerance to alloantigens in mixed leukocyte culture (MLC), cytotoxicity (CTL), delayed-type hypersensitivity assays (DTH), and challenge with a fresh CBA/j graft. Splenocytes from BALB/c recipients of photoinactivated splenocytes containing the effector cells of CBA/j alloantigen rejection proliferated poorly in MLC and generated lower cytotoxic T-cell responses to CBA/j alloantigens in comparison with sensitized and naive controls and suppressed the MLC and CTL response to alloantigen from sensitized and naive BALB/c mice. In vivo, the DTH response was specifically suppressed to the relevant alloantigen in comparison with controls. BALB/c mice treated in this fashion retained a CBA/j skin graft for up to 42 days post-transplantation without visual evidence of rejection. These results showed that reinfusion of photoinactivated effector cells resulted in an immunosuppressive host response which specifically inhibited in vitro and in vivo responses that correlate with allograft rejection and permitted prolonged retention of histoincompatible skin grafts.

Animals↗