Search PubMed⌕ Search

Biomedical subjects

E Reichel

Publications and source records attributed to E Reichel.

48 records · Page 3Linked to original sources
PubMed1989

An electroretinographic and molecular genetic study of X-linked cone degeneration.

We evaluated full-field electroretinograms from members of a family with X-linked cone degeneration. The 15-year-old propositus had near normal visual acuity and a protan deficiency. His maternal grandfather and great uncle had a visual acuity of 20/200, a deficiency in color vision, and signs of macular degeneration; all had normal rod electroretinographic responses and diminished cone electroretinographic responses. The mother and maternal aunt of the propositus had normal visual acuity and diminished cone electroretinograms with predominant loss of red cone function. Their cone responses were greater than those of affected males. Genomic DNA isolated from these patients was analyzed with a red cone pigment gene cDNA probe that disclosed a 6.5-kilobase deletion in the red cone pigment gene. These findings substantiate that a defect in a gene encoding for a cone photoreceptor protein can lead to a cone photoreceptor degeneration.

Adolescent↗
PubMed1989

First clinical experience with a Q-switched neodymium:YAG laser for urinary calculi.

Animal studies using a high intensity nanosecond pulsed neodymium:YAG laser did not reveal any serious tissue damage. Following these investigations patient treatment was begun in June 1987. Laser energy of a neodymium:YAG laser with an 8 nsec. pulse duration and a repetition rate of up to 50 Hz. was coupled into a flexible 600 resp. 400 micron. quartz fiber. Laser-induced breakdown was created with 35 to 50 mJ. at the fiber tip, resulting in a shock wave that disintegrated the calculus into tiny fragments. A total of 56 patients with 58 calculi (54 ureteral and 4 kidney stones) was treated from June 1987 to March 1988. Of the calculi 48 could be fragmented completely, while 6 others were reduced to a size small enough to be removed with forceps. Four stones composed of calcium oxalate monohydrate could not be disintegrated. The combination of laser stone disintegration with flexible ureterorenoscopy implies the possibility of an atraumatic, 1-step procedure for fragmentation of ureteral and kidney calculi.

Endoscopy↗
PubMed1989

Contact probes for intravascular laser recanalization. Experimental evaluation.

Experimental laser ablation of atheromatous plaques was performed with a bare quartz glass fiber, a metal probe, and a sapphire probe. The tissue response after irradiation with increasing energies was evaluated by means of light and scanning electron microscopy. Laser emission through the bare fiber caused a narrow, deep crater with an irregular surface surrounded by a zone of thermal necrosis. After tissue ablation with the metal probe, a disproportion between the small tissue defect and the large zone of thermal necrosis was observed. The largest tissue defect was vaporized by the sapphire contact probe. A small zone of thermal necrosis surrounded the laser crater.

Arteries↗
PubMed1989

The elastic modulus of central and perilimbal bovine cornea.

Data on the elastic properties of corneal tissue are needed to define the parameters involved in a model for radial keratotomy. Using bovine corneal tissue, we measured stress-strain relationships of tissue at different locations in the cornea. From this data we calculated Young's modulus of elasticity of five specimens at peripheral and central corneal locations. Increasing levels of stress produced increased resistance to stretch, a property typical of soft biologic materials such as cornea. Linear regression analysis of the data showed that the elastic modulus of the peripheral tissue was greater than that of central tissue at all values of applied stress. These linear relationships were statistically different, using an analysis of covariance, indicating that peripheral corneal tissue is stiffer than central corneal tissue. This information supports the suggestion that a peripheral circular ligament of corneal tissue exists and helps to maintain the curvature of the cornea. It is the disruption of this ligament that is believed to cause some of the change in corneal curvature when radial keratotomy is done.

Animals↗
PubMed1988

Laser induced shock wave lithotripsy--biologic effects of nanosecond pulses.

Laser energy of a Nd-YAG laser (1064 nm. wave length, 8 nsec pulse duration) was directed against various tissue cultures and the urothelium of the ureter, bladder and kidney parenchyma in pigs. Single pulse energy was 50 to 120 mJ with a repetition rate of 20 Hz. Urothelium and kidney parenchyma were irradiated in seven pigs. Tissue samples were examined histologically and electron microscopically directly, two, four, eight and 12 days after irradiation. No macroscopic lesion could be found. Maximum energy caused a small 'rupture cone' of 40 micron. depth. No thermic effects or necrosis resulted, so that no harm is to be expected with unintentional irradiation during laser stone disintegration.

Animals↗
PubMed1987

[Morphologic examination of the urothelium after irradiation with laser energy].

The energy of a Nd-YAG laser (1,064 nm wave length, 8 ns pulse duration) was used to irradiate the urothelium of the ureter or bladder and kidney parenchyma in pigs. Single pulse energy was 50-120 mJ with a 20-Hz repetition rate. The horizontal laser beam was reflected 90 degrees down by a 100% mirror and with a specially designed apparatus focussed on the surface of the tissue. Laser light from a quartz glass fiber was also focussed directly onto the tissue. Urothelium and kidney parenchyma were irradiated in 7 pigs. Tissue samples were examined histologically and raster electron microscopically 2, 4, 8 and 12 days after irradiation. No macroscopic lesion could be found. Maximum energy caused a small cone of 40 micron depth. No thermic effects or necrosis resulted, so that no harm is to be expected with unintentional irradiation.

Animals↗
PubMedDate not supplied

Optical coherence tomography after laser photocoagulation for clinically significant macular edema.

BACKGROUND AND OBJECTIVE: To demonstrate the utility of optical coherence tomography (OCT) for documenting an early response to laser photocoagulation in clinically significant macular edema (CSME) secondary to diabetes. PATIENTS AND METHODS: Five eyes of four patients were selected for review based on the diagnosis of CSME. All eyes had a clinical diagnosis of CSME based on slit lamp biomicroscopy. All eyes underwent focal/grid laser photocoagulation to areas of retinal thickening detected by OCT and clinical exam. Pre and post-treatment optical coherence tomograms were obtained for all patients. RESULTS: All eyes selected for review had an early positive response to focal laser photocoagulation. OCT was useful for demonstrating areas of retinal thickening prior to laser treatment. Serial macular maps demonstrated the resolution of retinal thickening after laser photocoagulation in all eyes. CONCLUSION: OCT is a useful tool for evaluating and documenting CSME both before and after focal/grid laser photocoagulation. OCT is capable of detecting an early positive response to photocoagulation for macular edema.

Aged↗
PubMedDate not supplied

Transpupillary thermotherapy for age-related macular degeneration: long-pulse photocoagulation, apoptosis, and heat shock proteins.

OBJECTIVE: To provide a biophysical foundation for using transpupillary thermotherapy (TTT) to manage choroidal neovascularization in age-related macular degeneration (ARMD). METHODS: Retinal temperature rise in laser therapy is proportional to retinal irradiance (laser power/area) for a particular spot size, exposure duration, and wavelength. TTT is a low irradiance, large spot size, prolonged exposure (long-pulse), infrared laser photocoagulation protocol. Results from an experimentally confirmed, finite element model of retinal light absorption and heat conduction are used to analyze laser parameter selection and its consequences. Results from apoptosis, heat shock protein and hyperthermia research are used to examine how chorioretinal damage from clinical procedures might be reduced. RESULTS: Chorioretinal thermal equilibration occurs during long-pulse TTT photocoagulation. Retinal temperature increases are similar in the RPE where laser radiation absorption is significant and in the adjacent neural retina where there is negligible radiation absorption. For parameters used to treat occult choroidal neovascularization in lightly-pigmented fundi (800-mW, 810-nm, 3-mm retinal spot diameter, 60-sec exposure duration), the maximum chorioretinal temperature elevation is calculated to be roughly 10 degrees C, significantly lower than the 20 degrees C temperature elevations measured in threshold, conventional short-pulse retinal photocoagulation. CONCLUSIONS: To achieve a preselected temperature rise, TTT laser power must be increased or decreased in proportion to the diameter rather than the area of the laser spot. Clinical power settings should be adjusted for fundus pigmentation and media clarity because both of these factors affect absorbed retinal irradiance and thus retinal temperature rise. Noninvasive thermal dosimetry currently is unavailable for clinical retinal photocoagulation, but potential thermometric techniques include MRI, liposomal-encapsulated dyes, multispectral imaging or reflectometry, and subretinal or episcleral thermometry. TTT may be useful not only as independent therapy, but also as an adjunct to PDT, antiangiogenic drugs and ionizing radiation therapy in the management of neovascular ARMD. Low temperature, long-pulse photocoagulation is a potential strategy for decreasing neural retinal damage in subsequent TTT or short-pulse photocoagulation and perhaps even for treating glaucoma or retinal degenerations.

Animals↗
PubMedDate not supplied

[Chronic renal insufficiency in the terminal stage. Therapeutic possibilities offered by repeated dialysis and transplantation in the absence of selection. Apropos of 136 cases].

Repeated dialysis in hospital or at home, and renal transplantation, carried out mainly with cadaver kidney, should permit in France, in the near future, treatment of all patients with chronic terminal renal failure. This report shows the results obtained between the 1st of November 1972 and the 1st of January 1975 in 136 patients treated without any selection at the Nephrology Department and Renal Transplantation Unit of the Pitié-Salpĕtrière Hospital in Paris, in connection with 20 public and private dialysis centers. 66 patients, i.e. 45% of all, were "high risk" patients, mainly because of their age or cardiovascular condition. The overall percentage of survival rate at 2 years in dialysed patients was 81%. It was 67% in the high risk group and 94% in the others. About half of the deaths occured because of cardiovascular reasons. 82 patients were considered for transplantation. Owing to the lack of donors, the number of transplanted patients was only 21. 19 transplantations were carried out with cadaver kidneys. On the 31st of December 1974, 15 patients, i.e. 71% lived with a functioning transplant. In the reported series, complete rehabilitation was obtained in 30% of cases. The results obtained justify, in our opinion, the policy of non-selection of patients.

Adolescent↗
PubMedDate not supplied

Indocyanine green angiography for recurrent choroidal neovascularization in age-related macular degeneration.

BACKGROUND AND OBJECTIVE: Recurrence of choroidal neovascular membranes (CNV) occurs frequently following laser photocoagulation. Recurrent CNV can be difficult to treat because they may not be well defined by fluorescein angiography. PATIENTS AND METHODS: The fluorescein and indocyanine green (ICG) angiograms of 58 eyes of 57 patients who presented with clinically suspected recurrence were evaluated retrospectively. RESULTS: In 14 eyes (24%), a well-defined recurrent CNV could be identified by evaluating the fluorescein angiogram. In 6 (14%) of the remaining 44 eyes, a well-defined recurrent CNV was identifiable by ICG angiography. CONCLUSION: A role for ICG angiography in the care of patients with suspected recurrent CNV is discussed.

Aged↗