Biomedical subjects

G Richard

Publications and source records attributed to G Richard.

At least 109 records · Page 6Linked to original sources

PubMed1997

[Alpha/beta and gamma/delta T-cell receptors--analysis of conjunctival tissue of patients with ocular pemphigoid].

BACKGROUND: In the conjunctiva of asymptomatic persons and patients with ocular cicatricial pemphigoid the existence and distribution of alpha/beta- and gamma/delta-T cell receptor (TCR)-positive cells has not previously been investigated. PATIENTS AND METHODS: Biopsy specimens from 20 patients with clinically diagnosed ocular cicatricial pemphigoid (OCP) were compared with 20 specimens from asymptomatic persons. Additionally, 3 specimens from patients with OCP treated with cytotoxic drugs and 8 specimens from patients who had undergone mucosal transplantation were studied. Antigen retrieval was done in deparaffinized specimens for immunohistochemical identification of alpha/beta- and gamma/delta-TCR-positive cells by monoclonal antibodies and an appropriate detection system. All steps were performed in triplicate, and negative control sera were applied. RESULTS: alpha/beta-TCR-positive cells were observed in the conjunctival epithelium and stroma of all the asymptomatic persons and in all patients with OCP. gamma/delta-TCR-positive cells were found in 4 out of 20 patients with OCP in epithelial sites, but not in asymptomatic persons. Patients with OCP who had received cytotoxic treatment exhibited neither alpha/beta- nor gamma/delta-TCR-positive cells. Staining sites of alpha/beta-TCR-positive cells changed from membrane-bound to nuclear in patients who had undergone mucosal transplantation, and were cytoplasmic rather than membrane-bound in gamma/delta-TCR positive cells. CONCLUSIONS: This study presents preliminary evidence for the existence of distinct T-cell subsets in the conjunctiva of healthy persons and of patients with OCP. Further functional studies in fresh tissue material may provide better insights into the role of defined T-cell subsets in the immunopathogenesis of autoimmune diseases of the outer eye such as OCP.

Biopsy↗

PubMed1997

[Change in corneal sensitivity after topical dorzolamide administration. A comparative study].

BACKGROUND: The new antiglaucoma drug, dorzolamide, mainly evokes local side effects like eye burning, pruritus, blurred sight and a foreign-body sensation. A clinical study was conducted to determine it dorzolamide has any influence on corneal sensitivity. SUBJECTS AND METHODS: We examined three different groups of substances. We used sodium chloride solution 0.9% and the local anesthetic oxybuprocaine 0.4% as control groups, each in two subgroups aged 23-40 years or 60-86 years. Corneal sensitivity was measured in the corneal center with Draeger's electronic optic aesthesiometer. We took the measurements directly before and 1,5,10,15 and 20 min after applying one eye drop. RESULTS: The control groups with sodium chloride solution showed no significant (P > 0.05) corneal hyposensitivity. The local anesthetic caused corneal asensitivity (P < 0.05) until the 10-min measurement. Twenty minutes after giving the anesthetic, with 12.10(-5) N corneal sensitivity nearly reached the starting value. At this time corneal sensitivity in the older subgroup was still decreased with 627.10(-5) N. In the younger subgroup dorzolamide only caused slight, but significant (P < 0.05), hyposensitivity of the cornea 1 and 5 min after application of the eye drop. CONCLUSION: Although dorzolamide decreases corneal sensitivity only a little, people with glaucoma using contact lenses should not insert them until at least 15 min after applying the dorzolamide.

Adult↗

PubMed1997

[Effect of various ablation levels on endothelial density in the enucleated pig eye. Experimental study with the 193 nm Excimer laser].

UNLABELLED: The effects of deep excimer laser ablations on the corneal endothelial cell count are still unknown. MATERIALS AND METHODS: In an in-vitro study the endothelial cell counts of 125 pig corneas were examined after excimer laser ablation. Five groups of 25 eyes reach, one control group and four groups with 3, 10, 20, and 35 D of ablation were examined. After the laser treatment, a corneoscleral disc was prepared and stored for up 5 days in an organ culture medium. The endothelial cell density of 5 corneas in each group was measured in a period of 5 days with a phase contrast microscope. RESULTS: Significant cell loss, 13-25%, was measured in each group after 5 days. There were no significant differences between the ablated corneas and the control group. CONCLUSION: Deep excimer laser ablations do not significantly reduce the endothelial cell count.

Animals↗

PubMed1997

[Changes in corneal thickness and endothelial cell density after cataract extraction using phacoemulsification].

UNLABELLED: Corneal metabolism is reduced after cataract extraction. PATIENTS AND METHODS: In a prospective study the corneal thickness and endothelial cell count of 48 patients were examined after phacoemulsification. Corneal thickness was measured with an ultrasound pachymeter and the endothelial cell count with a contact endothelial camera at the 12 o'clock position and in the corneal center before and 4 weeks, 4 months and 1 year after operation. RESULTS: One year after the operation, corneal thickness increased about 9% in the 12 o'clock position and about 12% in the corneal center. The endothelial cell count decreased about 27% in the 12 o'clock position and about 18% in the corneal center. We measured a significant correlation between cell loss and age at both points. Concerning the corneal thickness, no significant correlation was found. CONCLUSION: After cataract extraction corneal metabolism is reduced. The endothelial cell count or corneal thickness can be used as an indicator of the corneal trauma resulting from the operation.

Aged↗

PubMed1997

[Measuring intraocular pressure in keratoconus. Effect of the changed biomechanics].

BACKGROUND: Keratoconus is associated with changes in the corneal structure, such as defects of Bowman's layer, a decrease of corneal thickness etc. They result in alterations of some of the biomechanical parameters of the cornea, namely, rigidity and elasticity. The present study was performed to examine how impression tonometry and applanation tonometry for determination of intraocular pressure (IOP) are affected by the changed biomechanical parameters associated with keratoconus. PATIENTS AND METHODS: We examined 20 normal subjects (40 eyes) and 17 keratoconus patients (25 eyes). The corneal thickness was measured by ultrasound pachymetry in the corneal center. In the keratoconus patients, an additional measurement was made at the conus peak. The corneal curvature was determined using the TMS keratoscope. The IOP measurements were made with the Schiötz tonometer (10 g). For comparison, additional IOP measurements in the corneal center and, in the keratoconus group, on the conus peak were made with the applanation tonometer. RESULTS: The normal subjects had a central corneal thickness of 548 +/- 30 microns, compared to 505 +/- 42 microns in the corneal center and 425 +/- 41 microns on the conus peak in keratoconus patients. The average corneal curvature was 43.3 +/- 1.8 D in the normal subjects and 47.8 +/- 4.1 D in keratoconus patients. Applanation tonometry produced results on 11.33 +/- 1.43 mm Hg in the normal group (corneal center) compared to values of 12.00 +/- 2.55 mm Hg (corneal center) and 7.30 +/- 1.95 mm Hg (conus peak) in the keratoconus cohort. The coefficient of rigidity was 0.0236 +/- 0.0026 microliter-1 in the normal subjects, compared to 0.0173 +/- 0.0050 microliter-1 in the keratoconus patients. CONCLUSION: The morphological changes associated with keratoconus may cause tonometry errors.

Adult↗

PubMed1997

Trafficking of wheat gluten proteins in transgenic tobacco plants: gamma-gliadin does not contain an endoplasmic reticulum-retention signal.

Wild-type and mutated forms of the wheat (Triticum aestivum L.) storage protein gamma-gliadin were expressed in transgenic tobacco (Nicotiana tabacum L. cv. NVS) under the control of the 35S cauliflower mosaic virus (CaMV) promoter in order to determine what, if any, endogenous targeting signals are present in the wild-type gamma-gliadin protein. The mutant forms of the protein were modified by the addition of a KDEL or HDEL C-terminal endoplasmic reticulum-retention signal, or the addition of a C-terminal propeptide from barley lectin which has been shown to be necessary and sufficient for targeting to the vacuole. Only modified forms of the protein accumulated in leaves of transgenic tobacco, although the transcript levels were similar for all the constructs. Pulse-chase analysis indicated that whereas the wild-type gamma-gliadin was rapidly turned over in tobacco leaves, KDEL and HDEL forms were highly stable. The vacuolar-signal mutant protein accumulated in tobacco leaves, but migrated on sodium dodecyl sulphate-polyacrylamide gel electrophoresis with a lower mobility than wild-type gamma-gliadin, due in part to glycosylation of the C-terminal propeptide. The vacuolar-signal mutant protein was turned over slowly in tobacco, perhaps indicating a poor level of transport competence. When pulse-chase analysis was carried out on protoplasts isolated from tobacco plants expressing wild-type gamma-gliadin, but in the presence of Brefeldin A, gamma-gliadin was seen to accumulate. Taken together, these results indicate that gamma-gliadin is targeted to the vacuole in transgenic tobacco plants and does not contain any structural determinants which confer retention in the endoplasmic reticulum.

Brefeldin A↗

PubMed1997

Molecular genetic analysis of two families with keratosis follicularis spinulosa decalvans: refinement of gene localization and evidence for genetic heterogeneity.

X-linked keratosis follicularis spinulosa decalvans (KFSD) is a rare disorder affecting both skin and eyes. In the two extended KFSD families analysed to date, the gene was mapped to Xp22.13-p22.2. By analyzing several new markers in this region, we were able to narrow the candidate region to a 1-Mb interval between DXS7161 and (DXS7593, DXS7105) in the large Dutch pedigree. In addition, we analyzed 23 markers in Xp21.2-p22.2 in a German family with KFSD. Haplotype and recombination analysis positioned the KFSD gene in this family most likely outside the candidate region on Xp22.13-p22.2. This finding is suggestive for genetic heterogeneity: in this pedigree there is either another locus on the X-chromosome, or KFSD is transmitted here as an autosomal dominant trait with variable expression.

Child, Preschool↗

PubMed1997

[Endothelial cell loss after phacoemulsification with the "reversed tip and snip" technique compared with the "divide and conquer" technique].

BACKGROUND: The endothelial cell count after phakoemulsification is a sensitive parameter to compare different phakoemulsification techniques. PATIENTS AND METHOD: In a prospective study 30 patients in each group were operated upon the "Reversed Tip and Snip" and with the "Divide and Conquer"-Technique. The corneal endothelial cell count was measured before surgery and 4 weeks and 3 months after the operation. RESULTS: The endothelial cell count was reduced significantly about 10% after the the "Reversed Tip and Snip" and about 15% after the "Divide and Conquer"-Technique. The first mentioned technique had a significantly reduced cell loss than the latter. CONCLUSION: The "Reversed Tip and Snip" phakoemulsification technique causes less endothelial cell loss than the "Divide and Conquer"-Technique.

Aged↗

PubMed1997

[Development of corneal sensitivity after phacoemulsification with scleral tunnel incision].

BACKGROUND: after anterior segment surgery the anatomical structures and in particular corneal metabolism and corneal trophic are reduced. The corneal wound healing might be monitored by measuring corneal sensitivity. MATERIAL AND METHOD: In a prospective study of 1 year corneal sensation of 26 patients, age = 72.49 +/- 11.09 years, after phacoemulsification with scleral tunnel is examined. Corneal sensitivity is measured with the Draeger aesthesiometer in the corneal center, in the 6 o'clock and 12 o'clock position before and 4 weeks, 4 months and 1 year after the operation. RESULTS: The preoperative corneal sensitivity thresholds before the operation are with 11.61 +/- 10.49 x 10(-5) N in the 12 o'clock position, in the center with 2.43 +/- 2.57 x 10(-5) N and in the 6 o'clock position with 11.86 +/0 10.37 x 10(-5) N normal. Even 1 year after surgery corneal sensitivity is markedly reduced with 257.08 +/- 306.71 x 10(-5) N, 107.77 +/- 246.76 x 10(-5) N and 82.81 +/- 140.77 x 10(-5) N in the 6 o'clock position. CONCLUSION: Even 1 year after phacoemulsification corneal sensitivity is definitely hyposensitive in the center and descretely hypotensitive in the periphery at the 6 o'clock.

Adult↗

PubMed1997

Linkage studies in erythrokeratodermias: fine mapping, genetic heterogeneity and analysis of candidate genes.

Erythrokeratodermias are a clinically heterogeneous group of rare autosomal dominant disorders of cornification with overlapping features including hyperkeratosis and erythema. We ascertained five extended pedigrees with different phenotypes for a linkage study. Three families presented with localized erythrokeratodermia variabilis, and one with erythrokeratodermia and ataxia. Another family had Greither disease associated with variable hyperkeratotic plaques. Despite their phenotypic differences, both erythrokeratodermia variabilis and erythrokeratodermia with ataxia map to a common region in 1p34-p35. Multipoint linkage and haplotype analyses place erythrokeratodermia variabilis between the marker D1S496 and D1S186 with a maximum LOD score of 12.88. Our linkage results provide compelling evidence for genetic homogeneity among families of mixed European and French-Canadian origin. In contrast, results excluded Greither's disease from the established erythrokeratodermia variabilis gene region indicating genetic heterogeneity of erythrokeratodermias. Based on recombinations, two genes assigned to 1p34-p35 were excluded: cartilage matrix protein and avian myelocytosis viral oncogene. Connexin-37 (GJA4), a member of the connexin gene family, maps within the erythrokeratodermia variabilis region and is an attractive candidate gene. Direct sequencing of the coding region of GJA4 in four patients revealed several variations, including a novel polymorphism within the 5' cytoplasmic domain, but no pathogenic mutations were found, thus excluding Connexin-37 as a candidate. There is evidence, however, that other epidermally expressed connexins cluster in this region, and one may yet be determined to play a role in the pathogenesis of erythrokeratodermia variabilis.

Chromosome Mapping↗

PubMed1997

Killing kinetics of RP 59500 and pristinamycin against penicillin-resistant pneumococci.

The killing kinetics of two streptogramins, RP 59500 and pristinamycin against seventeen isolates of penicillin-susceptible and resistant pneumococci were studied. The antibiotics were tested at 1x, 2x and 4x the MIC for each individual isolate. The results showed a very good and rapid bactericidal activity within 1 hour for concentrations equal or greater to the MIC. These antibiotics are very promising agents for the treatment of infections due to multiresistant pneumococci.

Anti-Bacterial Agents↗

PubMed1996

Treatment of respiratory failure using minitracheotomy and intratracheal oxygenation in selected patients with chronic lung disease.

OBJECTIVE: To evaluate the efficacy of minitracheotomy (MT) insertion for intratracheal oxygen insufflation (ITO2) on arterial blood gases and survival in patients with respiratory failure from chronic lung disease. DESIGN: Open, prospective clinical study. SETTING: A 12-bed medical intensive care unit in a non-university hospital. PATIENTS: 20 patients (14 males and 6 females, mean age 74.8 +/- 2.6 years), admitted for respiratory failure and denied mechanical ventilation. INTERVENTION: Percutaneous insertion of an MT for ITO2. Arterial blood gases were drawn just prior to, then 3, 24, 48 h and 1 week after MT insertion. Data are evaluated with a two-way analysis of variance for distribution-free data (Friedman's rank sums test). MEASUREMENTS AND RESULTS: Three hours after starting ITO2, the partial pressure of oxygen in arterial blood (PaO2) and the arterial oxygen saturation (SaO2) both increased from 51.7 +/- 2.8 to 85.4 +/- 5.6 mmHg and from 79.7 +/- 3.1 to 93.7 +/- 0.9%, respectively (p < 0.001 for both), along with a slight worsening in the partial pressure of carbon dioxide in arterial blood (PaCO2), from 59.6 +/- 2.5 to 63.5 +/- 3.0 mmHg (p < 0.05). At 1 week, improvements in PaO2 and SaO2 were maintained in all patients, while PaCO2 decreased in 14 patients (mean decrease 8.3 mmHg) and increased in the remaining patients (mean 12.5 mmHg), when compared to pre-ITO2 values. Seven patients died during follow-up, leading to a success rate of 65%. Eight and 4 patients were discharged home and to a nursing home, respectively, 9 still receiving ITO2 via MT as chronic oxygen therapy. CONCLUSION: Our results suggest that MT insertion for ITO2 may be a therapeutic option in selected patients with respiratory failure from CLD.

Aged↗

PubMed1996

Alpha/beta- and gamma/delta-T-cell-receptor-positive lymphocytes in healthy and inflamed human conjunctiva.

BACKGROUND: The possible existence and distribution patterns of alpha/beta- and gamma/delta-TCR+ cells, which are important constituents of immune surveillance and act via the CD3+ cell complex have not yet been elucidated in the healthy and inflamed conjunctiva. MATERIALS AND METHODS: Paraffin-embedded conjunctival specimens included 18 from 18 patients with ocular cicatricial pemphigoid (OCP), 20 from 20 healthy controls, 6 from 6 patients with lye burns, and 6 from 2 patients with Stevens-Johnson syndrome; all were worked up by histology and immunohistochemistry. RESULTS: alpha/beta-TCR+ cells were visualized in the conjunctival epithelium and stroma of healthy persons, OCP, lye burns and Stevens-Johnson syndrome. alpha/ beta-TCR+ cells and a small number of gamma/delta-TCR+ cells were observed in the corneal epithelium and stroma of patients who have failing corneal grafts. After ileal mucosa transplantation to the epibulbar conjunctiva, membrane staining changes to nuclear and cytoplasmic staining. Treatment with systemic cytotoxic drugs abolishes all alpha/beta-TCR+ and gamma/delta-TCR+ cells. CONCLUSIONS: alpha/beta-TCR+ cells can be found in the non-infected epithelium and stroma of the healthy and inflamed (OCP, lye burns, and Stevens-Johnson syndrome) conjunctiva, as well as in the corneal epithelium and stroma of failing corneal grafts, whereas gamma/delta-TCR+ cells are absent. A small number of gamma/delta-TCR+ cells are present in the corneal stroma and adjacent conjunctival epithelium of patients with chronic corneal graft rejection or after transplantation of gut tissue. Further investigations may establish the role, if any, of these T-cell subsets in immune surveillance of the non-infected outer eye and in corneal graft rejection.

Burns, Chemical↗

PubMed1996

Hydrodynamic function of tilting disc prostheses and bileaflet valves in double valve replacement.

OBJECTIVE: To determine the energy loss attributable to prosthetic valve size and design in double valve replacement, energy consumption of mitral valves (size #25 to #29), of two different designs (Bjork Shiley tilting disc and Carbomedics bileaflet valves), in combination with a small (#21) and large sized (#27) aortic prosthesis, were analyzed in a flow simulator. METHODS: A pulsatile flow simulator was used to reproduce physiological ventricular dynamics and to match the input and output impedances of the human left ventricle. Hydrodynamic performance was determined as stroke work, closing work and leak work for each combination of valves at low flow (5 liters per minute) and high flow (9 liters per minute) conditions. RESULTS: At low flow no decrease of energy requirement was found with the use of a mitral valve larger than #25. At high flow the #27 and #29 mitral valves required less energy compared to a #25 mitral valve, in combination with a large aortic prosthesis. The #29 mitral prosthesis revealed similar results as the #27. With the use of a large aortic prosthesis a remarkable reduction of total flow work was shown. These results were found in both designs. In comparison of the two designs, tilting disc valves required more energy for stroke and closure of the valve, although less energy for leakage. In total, energy requirements were higher for tilting disc valves. COMMENTS: A hydrodynamic advantage for the use of a mitral valve larger than #25 was found only with the combination of a large aortic prosthesis and high flow. Hydrodynamic data favor the use of bileaflet prosthesis especially for a patient who is expected to exercise.

Aortic Valve↗

PubMed1996

[Descemetocele after Excimer laser phototherapeutic keratectomy in herpes simplex virus-induced keratitis: a clinico-pathologic correlation].

BACKGROUND: The indications for phototherapeutic keratectomy in superficial and deep corneal scars in Herpes simplex virus infections are controversial. Serious incidents after PTK have as yet not been reported. PATIENTS AND METHODS: A 62-year-old patient had suffered from recurrent central herpetic keratitis since 1948 and was treated for corneal scarring for the first time in 1992 by PTK. In 1995, epithelial defects were noted and, since medical treatment was unsuccessful, repeat PTK was performed. Two weeks after the second PTK, stromal infiltration with a subsequent corneal ulcer was followed by a descemetocele and perforation. RESULTS: The recurrence of Herpes simplex keratitis was treated with systemic acyclovir, and the corneal perforation, the posterior synechiae and the complicated cataract were managed by a triple procedure à chaud (7.0 x 7.5 mm). The inflammation calmed down, and a significant improvement of vision was noted at dismissal. Histopathology of the corneal button showed no epithelial cells, endothelial cell rarefication, loss of Bowman's layer resulting from PTK, stromal edema, a descemetocele with perforation of 1.5 mm in diameter, and immunohistochemically Herpes simplex virus in the deep stroma and pre-Descemet. CONCLUSIONS: Considering the clinical data and the histopathology we conclude that repeat excimer laser phototherapeutic keratectomy of herpetic keratitis without antiviral coverage may result in complications.

Cicatrix↗

PubMed1996

[Rhegmatogenous retinal detachment in atrophia gyrata: pars plana vitrectomy with silicone oil instillation].

BACKGROUND: Gyrate atrophy is a form of choroidal dystrophia characterized by a genetic defect of the mitochondrial matrix enzyme ornithine ketoacidoaminotransferase on chromosome 10. Apart from rare myopathic problems, cases of choroidal, iridal atrophy, complicated subcapsular cataract, optic atrophy, macular edema, reticular retinoschisis, vasculitis and perivasculitis could be observed so far. To our knowledge, rheumatogenous retinal detachment has been described before. We present a 34-year-old female subject with a retinal detachment of the right eye over 3 quadrants with 3 small round foramina in the area 10 to 11 o'clock. PATIENTS: Concentric defects of the visual field had been known since the age of 4; the patient was slightly myopic. At the age of 31, the patient had undergone cataract extraction with implantation of posterior chamber lenses in both eyes. The ophthalmological examination revealed large areas of choroidal atrophia in both eyes. A determination of visual acuity resulted in hand movements in the right eye and 0.1 in the left eye. The ERG was extinguished. RESULTS: The retina could be fully reattached by pars plana vitrectomy and instillation of silicone oil. At the same time, we performed an excision of secondary cataract. On demission, the visual acuity of the right eye was finger counting. Because a brother of the patient had also suffering from a progressive choroidal atrophy since his childhood, an autosomal recessive disease was suspected. The only abnormality detected was strongly elevated plasma levels of ornithin (7.5 to 14 mg/dl, compared to levels of 0.6 to 2.0 in controls). Urinary excretion of ornithin was also strongly increased. DISCUSSION: To our knowledge there was no previous description of a case of atrophia gyrata in association with rhegmatogenous retinal detachment after intraocular surgery. As the pigment epithelium is missing, intraoperative endolaser-coagulation would be useless. For this reason, and since a tendency for reattachment is lacking consistent with one of the characteristics of this disease, the only approach to this case is intraocular tamponade with silicone oil.

Adult↗

PubMed1996

Killing kinetics of meropenem against penicillin-resistant pneumococci.

The killing kinetics of meropenem against sixteen clinical isolates of pneumococci (12 penicillin-resistant, three penicillin-intermediate and one penicillin-sensitive) were studied. Meropenem was tested at 1x, 2x and 4x the MIC for each individual isolate. The results showed a good bactericidal activity with rapid killing of pneumococci (killing > 3 log10 cfu/mL was obtained for nine strains). This strategy needs clinical assessment and might prove to be a suitable alternative to penicillin and cephalosporins for the treatment of mixed infections involving multiresistant pneumococci.

Meropenem↗

PubMed1996

Evidence for genetic heterogeneity in monilethrix.

Monilethrix is a rare inherited defect of the hair shaft resulting in hair fragility and dystrophic alopecia. In contrast to recent reports mapping monilethrix to the type II epithelial and trichocyte keratin gene cluster on 12q13, we strongly excluded these candidate genes in another family with autosomal dominant monilethrix. Moreover, there was no evidence for linkage of the disease to the keratin gene cluster on chromosome 17q12-q21, thus excluding defects in all known trichocyte and epithelial keratins as the cause of monilethrix in this family. Likewise, several other genes known to play an important role in hair shaft formation (trichohyalin and involucrin, ultra-high sulfur matrix proteins, and transglutaminases 1, 2, and 3) did not provide any evidence for linkage. Our results indicate genetic heterogeneity in monilethrix and suggest that aberrations in at least one other gene result in a similar phenotype.

Age Factors↗