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Biomedical subjects

J A Bernard

Publications and source records attributed to J A Bernard.

At least 19 recordsLinked to original sources
PubMed2002

Alpha3 integrin receptors contribute to the consolidation of long-term potentiation.

Several lines of evidence suggest that integrin receptors play a pivotal role in consolidation of long-term potentiation (LTP), but which of the many integrin dimers are involved remains to be discovered. The present study used an LTP reversal paradigm to test if alpha3 integrins make an important contribution. Function blocking alpha3 monoclonal antibodies or vehicle were locally infused into recording sites in field CA1 of rat hippocampal slices and LTP induced with theta burst stimulation. Low frequency trains of pulses were applied 30 min after the theta bursts. Previous work indicates that low frequency stimulation reverses LTP when applied immediately after induction but is largely ineffective after 30-45-min delays. If the antibodies were to block consolidation, then they should extend the period over which potentiation is vulnerable to disruption. There was no detectable difference between the two groups in the initial degree of LTP or within slice decay of potentiation 1-10 min after induction; a small but reliable decay occurred from 10 to 30 min with antibody treatment (P<0.01) but not in control slices. Percent potentiation was not statistically different for vehicle (55 +/- 19%, mean +/- S.D.) and anti-alpha3 (43 +/- 21%) slices at 30 min post-theta bursts. Five-Hz stimulation ("theta pulse" stimulation) 30 min after induction caused a reduction of LTP. The percent loss of potentiation after the 1-min trains was greater in the antibody-treated slices than in controls (98 +/- 4% vs. 62 +/- 28%, P<0.01, U-test) and correlated (r=0.84, alpha3 slices) with the percent LTP present prior to low frequency stimulation, as expected if the stimulation reversed potentiation. Recovery occurred in both groups but percent LTP was significantly smaller in experimental slices at 10 min post-theta pulses (5 +/- 11% vs. 36 +/- 15%, P<0.01). Recovery continued for 20 min after theta pulses and, in accordance with earlier work, was nearly complete for the control slices (50 +/- 19% vs 55 +/- 15%, 40 min post- vs. immediately pre-theta pulses). LTP remained depressed after 40 min of recovery in the anti-alpha3 slices (23 +/- 19% vs. 43 +/- 21%) at which point it was substantially less than that found in controls (P<0.01). Western blots with anti-alpha3 antibodies identified a polypeptide with the molecular mass (155 kDa) expected for the alpha3 subunit and further showed that it is broadly distributed in brain. Subcellular fractionation experiments demonstrated that alpha3 is concentrated in synaptic membranes over homogenates to about the same degree as the GluR1 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate-type glutamate receptor. From these results we suggest that alpha3-containing integrins are localized to synapses and are needed to stabilize a slowly decaying form of LTP. The findings also show that vulnerability to reversal can be used in place of extended recording sessions in studying consolidation.

Animals↗
PubMed2001

[Retinal lesion due to an obstetrical traumatism: a case report].

The authors report a case of unilateral, stable, localized, and well-circumscribed choriocapillaris atrophy associated with retinal pigment epithelium dispersion and atrophy. The anterior segment was normal. Facial examination revealed a homolateral malar hypoplasia. The other eye was normal. The electrophysiologic study did not confirm pigmentary degeneration of the retina. The patient's history included a difficult delivery using obstetrical forceps. The authors review the main ocular lesions secondary to birth trauma. In this case, they favored a traumatic chorioretinal lesion secondary to an obstetrical traumatism. In this context, progressive facial hemiatrophy is the main differential diagnosis.

Atrophy↗
PubMed2000

[Endonasal dacryocystorhinostomy (DCR) with protected drill].

PURPOSE: To analyze the interest of protected drills to perform endoscopic endonasal DCR. MATERIAL AND METHODS: [corrected] Fifty patients suffering from chronic epiphora were operated successively. None of those patients had had prior nasal surgery. The same surgeons (BF and ER) did the surgical procedure for all the cases. The technical steps were: endoscopic visualization of the middle meatus and evaluation of the anatomic variations of the nose; identification of the lacrymal bag with a 1 mm light in the canaliculus; unciformectomy; the maxillary bone was drilled with a 3.2 mm bit (straightshot Xomed), protected and irrigated; the lacrymal bag was opened by cissors and the flap was pushed in the ethmoid and coagulated. RESULTS: The suction-irrigation system was efficient to clean the surgical site, with a good endoscopic control. The protected bit didn't damage the 4-mm optics and the septal wall mucosa, even in narrow noses. The staightshot bit (Xomed) was tough enough to drill the maxillary bone in only 68 % of the surgical cases. In 28 % the drilling was unsatisfactory and in 4 % it was inefficient. The functional results at 6 month were good in 85 %. There was no difference between normal and narrow noses. CONCLUSION: The concept of protected bits perfectly matches the endoscopic endonasal DCR. The visual comfort and security of the surgical procedure are increased. Short term results are equivalent to external DCR, but are rather inefficient and expensive.

Chronic Disease↗
PubMed1999

Grid photocoagulation for focal diabetic macular edema with focal leaks and hard exsudates involving the peri-foveolar area.

This study was conducted to determine whether indirect grid laser therapy is effective in reducing focal diabetic macular edema characterised by focal leaks and hard exsudates involving the para-foveal area (less than 300 microns from the center of the fovea). Since focal coagulation of microaneurysms in such a critical location can be deleterious, indirect grid pattern laser treatment may be used in such cases.

Adult↗
PubMed1995

[Eyelid and lacrimal abscesses].

Nonspecific eyelid abscesses are rare, whereas periorbital infections occur more frequently. Localisation of a maximum number of inflammatory signs is essential for diagnosis. A superior external localisation suggest dacryoadenitis or infection of a dermal cyst and the end of the eyebrow. An internal canthal localisation would reflect lacrimal disorder. In the adult, the main cause of infection is acute dacryocystitis. After antibiotic and anti-inflammatory drug treatment, dacryocystorhinotomy is necessary to preclude recurrence. In the newborn, bilateral forms of dilatation of the lacrimal sacs can lead to respiratory distress. The treatment of choice is resection of the endonasal pouches.

Abscess↗
PubMed1995

[Hard exudates in diabetic retinopathy].

In diabetic retinopathy the hard exudates are often arranged in a halo and correspond to a focal oedema. Their number may increase after correctly performed photocoagulation, and may decrease after a certain period. The central (macular) hard exudate may be subretinal and are a poor prognosis, leading to a fibrotic scar. When those exudates are more superficial, filling the cystoid spaces, they are of better prognosis.

Diabetic Retinopathy↗
PubMed1994

[Internal transient palpebral inclusion following dacryocystorhinostomy].

The authors report two cases of postoperative lagophthalmos immediately following ab externo dacrycystorhinostomy (DCR). Two female patients, aged 67 and 62 years, underwent under general analgesia for chronic dacryocystitis with mucocele. An inferior surgical approach, sparing the inner canthal ligament was chosen in both cases. Lagophthalmos was observed on the operated side on the first postoperative day. Normal lid occlusion was present on the contralateral side. Impairement of palpebral occlusion was predominant in the nasal portion of the lid fissure. Upon voluntary and reflex blinking, a reduction in the downward movement of the superior lid was observed. This reduction was not as apparent when the patients were asked to produce a forced blink. Lagophthalmos disappeared progressively over 3 postoperative months in both cases. Neither epiphora nor any corneal complications were observed. Lagophthalmos following DCR via an inferior approach is a previously unreported complication and may be related to the disinsertion of the nasal portion of the orbicularis muscle and periosteum at the time of periosteal cleavage. Recovery of normal lid function may be due to reattachment of the periosteum.

Aged↗
PubMed1993

[Transient internal palpebral inocclusion after dacryocystorhinostomy].

The authors report two cases of postoperative lagophthalmos immediately following ab externo dacryocystorhinostomy (DCR). Two female patients, aged 67 and 62 years, underwent under general analgesia for chronic dacryocystitis with mucocele. An inferior surgical approach, sparing the inner canthal ligament was chosen in both cases.

Aged↗
PubMed1992

[Canalicular stenoses complicating the insertion of lacrimal plugs. Incidence and mechanisms].

Changes in canalicular permeability following the insertion of punctum plugs was studied. This occlusive method was used to treat dry eye syndrome in 43 patients over a period of 32 months. All had normal canalicular patency, confirmed on the day of implantation. One hundred and five large plugs were used (2.4 plugs per patient). Twenty seven (25.7%) impassable acquired canalicular stenoses were seen in 15 patients. The canalicular site of the 27 stenoses was the same: junction between the vertical and horizontal portions. Among the 27 stenoses: 4 plugs had disappeared at an unknown time, with follow-up probing taking place after a mean interval of 7.5 (months range: 1 to 15 months); 17 plugs had been expelled after being in place for an average of 5 months (range: 1 to 12 months; standard deviation 3.47), with follow-up examination taking place on average 12 months after insertion (range: 6 to 17 months; standard deviation 3.4); and 6 plugs were still in place after a mean of 7 months (range: 2 to 15 months; standard deviation 4.73) and the stenosis was discovered when they were removed. They were intact. These 6 Cases eliminate any possibility of intra-canalicular migration of the prosthesis--of all or part--of the prosthesis. Stenoses appeared to develop rapidly: 45% of cases were discovered during the first 3 months. 16/27 (59%) of stenoses were investigated a second time, 6 months later on average (range: 2 to 12 months): these 16 canaliculi all remained impassable.

Aged↗
PubMed1991

[The dry eye].

After reviewing the anatomy and pathophysiology of the lacrimal circuit, the authors describe the diagnostic approach to dry eye syndrome. Two very different entities can be distinguished: acute dryness generally due to a defect of the palpebral lining, for which urgent treatment is required to prevent corneal perforation, and chronic dryness, generally due to a reduction of lacrimal secretion. The aetiological survey must look for a reversible cause, dominated by drugs. Treatment is symptomatic in every case, consisting of the regular prescription of artificial tears. The use of lacrimal plugs to obstruct the lacrimal draining ducts constitute second-line treatment and may improve the functional tolerance.

Acute Disease↗