Phosphorylation of the Hsp90 Co-Chaperone Hop Changes its Conformational Dynamics and Biological Function

The molecular chaperones Hsp90 and Hsp70 and their regulatory co-chaperone Hop play a key role at the crossroads of the folding pathways of numerous client proteins by forming fine-tuned multiprotein complexes. Alterations of the biomolecules involved may functionally impact the chaperone machinery: here, we integrate simulations and experiments to unveil how Hop conformational fitness and interactions can be controlled by the perturbation of just one residue. Specifically, we unveil how mechanisms mediated by Hop residue Y354 control Hop open and closed states, which affect binding of Hsp70/Hsp90. Phosphorylation or mutation of Hop-Y354 are shown to favor structural ensembles that are indeed not optimal for stable interactions with Hsp90 and Hsp70. This disfavors cellular accumulation of the stringent Hsp90 clients glucocorticoid receptor and the viral tyrosine kinase v-Src, with detrimental effects on v-Src activity. Our results show how the post-translational modification of a specific residue in Hop provides a regulation mechanism for the larger chaperone complex of which it is part. In this framework, the effects of one single alteration are amplified at the cellular level through the perturbation of protein-interaction networks.

Adult-onset Kaposiform hemangioendothelioma of the tongue: case report and review of the literature

We present here a very rare clinical case of a 38-year-old man with Kaposiform hemangioendothelioma (khe) of the tongue who presented to our institution with a growth under the left side of the tongue with no pain or discomfort. There were no enlarged lymph nodes and no significant neurologic findings. Diagnostic histopathology confirmed the lesion to be khe. The tumour was removed surgically, and the surgical specimen confirmed the diagnosis. Follow-up at 3 months shows no clinical evidence of recurrence.

Superficial extraconal blockade for vitreoretinal surgery

Context:

Needle length plays an important role for the success of ophthalmic block. The standard practice is to use 25 mm needles length; however, unnecessarily long needles may increase the risk of complications especially in the presence of staphyloma or previous scleral buckle.

Aims:

This work was designed to compare the efficacy of using 15 and 25 mm needle in performing extraconal block for patients undergoing vitreoretinal surgery.

Settings and Design:

Prospective randomized double blinded study.

Materials and Methods:

A total of 120 patients were enrolled in this study and were divided in two groups. In group (1) extraconal block was performed using 25 mm needle, while in group (2) 15 mm needle was used. After primary injection, assessment of the block was done by an anesthesiologist who was unaware of the needle used. If satisfactory akinesia was not achieved a supplementation was provided. At the end of the procedures, patients and surgeons were asked to assess their pain and satisfaction with the anesthetic technique.

Statistical Analysis used:

The sample size calculation using N-Quary version 4. Numerical and categorical data were analyzed using an independent sample, a two-tailed t-test, and chi-square test, respectively.

Results:

The volume of primary injectable was significantly higher in group 2. The two groups were comparable as regards total volume of local anesthetic, supplementation rate, akinesia, pain score, and surgeon satisfaction.

Conclusions:

Using 15 mm needle length to perform extraconal blockade for posterior segment procedures is equally effective to 25 mm needle.

Phacomorphic glaucoma associated with choroidal melanoma

Patients with phacomorphic glaucoma present with mature cataract, shallowing of the anterior chamber, and angle-closure glaucoma. The opaque ocular media due to cataract formation usually precludes visualization of the posterior segment of the affected eyes. The authors describe a 65-year-old man who presented with reduced vision and clinical findings typical of phacomorphic glaucoma. Preoperative ultrasonography revealed an intraocular tumor, and magnetic resonance imaging showed a high signal intensity in T1-weighted images and a low signal intensity in T2-weighted images consistent with choroidal melanoma. Histopathologic examination of the tumor after enucleation confirmed the diagnosis. The clinical findings characteristic of phacomorphic glaucoma may be associated with choroidal melanoma. Ultrasonography or other imaging studies should be performed on eyes with phacomorphic glaucoma and opaque ocular media to allow timely detection of any mass lesion and to guide appropriate surgical management.

Endophthalmitis cluster from contaminated donor corneas following penetrating keratoplasty

OBJECTIVE

To attempt to identify common events or factors in four cases of endophthalmitis that developed after penetrating keratoplasty performed within a 1-week interval.

DESIGN

Case series.

SETTING

Tertiary care eye hospital in Riyadh, Saudi Arabia.

PATIENTS

Four patients in whom endophthalmitis developed after penetrating keratoplasty performed in May 1993.

OUTCOME MEASURES

Source of donor tissue, transportation of corneas, handling of corneas at the eye hospital, and causative organism and sensitivity profile.

RESULTS

The donor tissue in all four cases originated from the same eye bank. Organisms were cultured from 10 of the 11 donor rims from eye bank A tissue used during the week in question. The causative organisms were Enterococcus faecalis in three patients and Torulopsis glabrata in one patient. In each case the same organism was cultured from the recipient eye and the corresponding donor rim. Two of the four patients had a favourable outcome.

CONCLUSIONS

Donor rim culture is essential if the cause of endophthalmitis after penetrating keratoplasty is to be determined. Close communication between eye bank personnel, the microbiology laboratory and the operating surgeon is important as it may influence early detection, choice of treatment and outcome of endophthalmitis after penetrating keratoplasty. Epidemiologic studies from both the source eye bank and the recipient facility are required to fully investigate the cause of a cluster of endophthalmitis cases from contaminated donor tissue following penetrating keratoplasty.

Tuberous sclerosis in infancy

PURPOSE

To report two infants with tuberous sclerosis who initially were considered to have retinoblastoma.

PATIENTS AND METHODS

An 8-day-old infant was referred with small tumors in the posterior poles of both eyes. A left microphthalmos with ciliochoroidal coloboma was present. Computed tomographic (CT) scanning of the brain showed scattered high-density subependymal foci in the lateral ventricle thought to be consistent with calcification resulting from intrauterine viral infection. Argon laser photocoagulation was applied to lesions in the right eye. Because one tumor was situated on the retina straddling the coloboma in the left eye, external beam radiotherapy was administered. A 5-month-old girl presented with a large mass in a left microphthalmic eye. Calcification was present on B-scan ultrasonography and CT scanning. Vitreous seeding was noted to originate from the tumor. The contralateral eye manifested four small gray translucent retinal tumors in the posterior pole. CT scan and magnetic resonance imaging (MRI) revealed multiple periventricular subependymal lesions, including one at the foramen of Monro.

RESULTS

Repeated examinations in the younger child under anesthesia revealed small new retinal lesions that appeared to enlarge gradually. She developed intractable seizures and her electroencephalogram revealed a modified hypsarrhythmia recording. A careful review of available CT scans and MRI displays suggested the diagnosis of tuberous sclerosis. The child's most recent examination under anesthesia revealed multiple newly developed hamartomas. In the older child, prompt diagnosis was made on the basis of the intracranial radiologic findings.

CONCLUSION

Retinal hamartoma presentation may vary in infancy. Small, initially fleck-like gliotic lesions appear to enlarge gradually and eventually may form gray, translucent tumors. Large astrocytic hamartomas of the retina associated with tuberous sclerosis may resemble retinoblastoma, particularly if the mass is large, calcified, and associated with vitreous seeding. Although ophthalmic presentation was reminiscent of retinoblastoma in both patients, radiologic evidence of subependymal hamartomas pathognomic for tuberous sclerosis helped establish the correct diagnosis. We stress the importance of intracranial radiologic findings in this regard.

Radiation therapy for retinoblastoma: a retrospective review of 120 patients

PURPOSE

To characterize the patient population and treatment outcomes in patients with Retinoblastoma (RB) referred for External Beam Orbital Radiotherapy (EBORT) to King Faisal Specialist Hospital & Research Centre (KFSH&RC), Riyadh, Saudi Arabia from 1976 to 1993.

METHODS AND MATERIALS

A retrospective study of 120 patients with RB affecting a total of 192 eyes. Patients were divided into three groups. Group A are 60 patients (64 eyes) treated with EBORT to the intact eye to preserve vision. Reese-Ellsworth (RE) Staging was: 1: 12%; 2: 10%; 3: 12%; 4: 23%; and 5: 43%. Twenty-eight patients (47%) also received Vincristine, Adriamycin, and Cyclophosphamide chemotherapy (C/T). Mean follow-up, per patient, was 48.5 months. Standard treatment until 1992 was 45 Gy in 12 fractions of 3.75 Gy, three times weekly over 18 days. Assuming the alpha/beta ratio for early effects and tumor control at 10, Tk = 21 days, Tpot = 5 days, then the Biological Equivalent Dose (BED) was 62 Gy10 for early effects, and 101 Gy3 for late effects. Group B are 28 patients (28 eyes) treated for curative intent with EBORT to the orbit for locally advanced disease, usually after enucleation (24 eyes). Nineteen patients (83%) also had C/T. Mean follow-up was 22.6 months. Group C are 37 patients with advanced disease treated with radiotherapy for palliation. Seventeen (46%) also received C/T. Mean follow-up was 11.7 months.

RESULTS

Group A-following EBORT useful vision was retained in RE Stage 1 to 5: 7 of 7, 6 of 6, 4 of 8, 10 of 15, and 7 of 28 eyes, respectively. There was no significant difference between patients who received adjuvant chemotherapy and those who did not. Complications included cataract (27%), retinopathy (25%), vitreous hemorrhage (19%), and orbital deformities (11%). In Group B the local control rate was 71%. In Group C, 10 (27%) of the 37 patients were alive at last contact, and 27 (73%) were either terminal or dead of disease. None of Group A or B patients had positive CSF cytology, bone scan, or bone marrow examination. In Group C 19% had positive CSF cytology, and bone marrow, and 14% had a positive bone scan.

CONCLUSIONS

1) EBORT preserved useful vision in a significant proportion of patients even in eyes with advanced RE Stage RB, but longer follow-up is likely to reveal an even higher complication rate with this regime. 2) High dose per fraction probably contributed to the increased complications. 3) Chemotherapy did not demonstrate any effect on retaining vision in this study. 4) For disease that is confined to within the eye clinically and radiologically, invasive procedures for CSF cytology, bone marrow examination, and bone scan do not seem warranted. 5) The optimum technique, fractionation, and dosage for RB is still not well defined.

Workup for metastatic retinoblastoma. A review of 261 patients

PURPOSE

The means available to screen for retinoblastoma metastases, including bone marrow aspiration, lumbar puncture, and radionuclide scans, offer variable usefulness at different stages of the disease. In this study, the authors attempted to assess the value of these tests as part of the initial workup for metastases.

METHODS

Medical files of 261 patients with retinoblastoma were reviewed, and the results of bone marrow, lumbar puncture, and bone and liver radionuclide scans were correlated with the laterality, clinical staging, and histopathologic findings. The presence or absence of tumor in the choroid and the optic nerve also were correlated with the results of diagnostic tests.

RESULTS

Of 261 patients with retinoblastoma, 147 (56.3%) and 114 (43.7%) had unilateral and bilateral disease, respectively; 11.6% of unilateral cases and 14.9% of bilateral cases had distant metastasis (P = 0.2). Bone marrow aspirations were performed on 101 patients (38.7%), and 10 (9.9%), of these specimens showed the presence of retinoblastoma cells in the aspirate. Ninety-four (36%) of the patients were examined with spinal tap cytology, and the results of four (4.3%) of these were positive for tumor cells. Radionuclide bone and liver scans were performed on 49 (18.8%) and 48 (18.4%) patients, respectively; 5 (10.2%) had abnormal bone scans and 3 (6.2%) had abnormal liver scans. The average age in the metastatic group was 3.1 years, whereas the average age in the nonmetastatic group was 2.3 years. All of our abnormal test results were found in patients with stages III and IV disease, with the exception of one abnormal lumbar puncture in a patient with stage II disease. The correlation of diagnostic tests with the histopathologic findings showed that with no choroidal involvement, no positive diagnostic tests were encountered. Correlation between positive diagnostic test results and the level of optic nerve involvement failed to indicate any trends.

CONCLUSION

Our study indicated a good interrelation between the positivity of diagnostic tests (bone marrow and bone scan) and higher stages of the disease (stages III and IV) and choroidal involvement in enucleated eyes, with statistically significant correlations; correlations with lumbar puncture and liver scan were not significant.

Drug abuse in schizophrenia: comparison of patients who began drug abuse before their first admission with those who began abusing drugs after their first admission

The relationship between the onset of drug abuse and onset of illness (first hospitalisation) and its correlates were examined in 42 hospitalised schizophrenics identified as drug abusers. 60% of the patients began drug use before their first hospitalisation. No differences on sociodemographic or clinical parameters between patients who began drug use before their first hospitalisation and those who began after it were detected when drug abuse was treated as a unitary phenomenon. Use of specific drugs was associated with significant differences in age, age at first hospitalisation, premorbid functioning and type of schizophrenia between patients who began drug pre-morbidly and those who began to use drugs post-morbidly. The differences were not uniform for the different drugs used. The findings are discussed in relation to vulnerability and self medication models of comorbidity of drug abuse and schizophrenia.

A new method for the evacuation of aqueous humor in uncontrolled glaucoma. The vitreo-tenonian tube

The vitreo-tenonian tube is a new procedure, used in uncontrolled glaucoma, for the drainage of aqueous humor. It presents three original characteristics: it is made of a stainless metal, it is implanted in the posterior segment after vitrectomy and it drains the aqueous humor in the subtenonian space. We will describe first the surgical technique for the implantation of the tube, and then we will present the results of the first eight cases treated by this method. The advantages and drawbacks of this type of drainage are discussed: they are compared with the other surgical techniques used in cases of glaucoma which is uncontrolled by the classical methods.

Classification of diabetic retinopathy

A review of the literature on the classification of diabetic retinopathy shows that a consensus of opinions is not attained. Therefore it is impossible to compare the results of different works. Most of the classifications are based on purely anatomical criteria (ophthalmoscopic or photographic). The authors propose to base the classification of diabetic retinopathy on angiographic criteria. They consider that only fluorescein angiography can take into consideration the functional evaluation of the retinal circulation with unquestionable pathogenic correlation and adapted treatment: edematous diabetic retinopathy corresponds to capillary dilatation and ischemic diabetic retinopathy corresponds to capillary occlusion. Macular diseases are classified according to these same criteria.

Trabeculoperforation? Trabeculoretraction? Trabeculoplasty? Review of the various designations used for laser treatment in primary open-angle glaucoma

A historical recall and an attempt to simplify the numerous terms used to designate laser treatments for primary open-angle glaucoma (POAG) are presented. There are two main types of laser treatment for POAG involving two entirely different procedures. The first one, contemporary with the beginning of laser photocoagulation, imitates the action of the scalpel, namely goniotomy ab interno or trabeculotomy ab externo. The goal of this early procedure was to produce a through and through trabecular hole but instead of the cutting edge of the knife, it uses the explosive effect of the laser. This procedure has been given numerous names. Among the most frequent ones, we find: 'laser trabeculopuncture', 'laseropuncture', 'goniopuncture', 'laser trabeculectomy', 'laser trabeculotomy', 'laser trabeculopexy'. We prefer to gather them under an explicit generic term: 'laser trabeculoperforation'. The results of this procedure have been very disappointing until now, particularly with conventional lasers, e.g. continuous-wave argon laser, owing to the predominance of their thermal effect over their explosive effect and also to the great scarring property of the trabecular meshwork. In the second type of glaucoma laser treatment, instead of trying to make a patent hole in the trabecular meshwork, the surgeon seeks to reshape the inner trabecular surface by means of argon laser microscars in order to produce a reversal of the trabecular collapse, which is now considered to be one of the major etiologies of POAG.(ABSTRACT TRUNCATED AT 250 WORDS)