Vincenzo Papa

Long term treatment with sodium hyaluronate-containing artificial tears reduces ocular surface damage in patients with dry eye

Background/aims: Several studies have reported that sodium hyaluronate is able to improve both symptoms and signs in patients with dry eye but none have demonstrated an improvement of conjunctival epithelial cell abnormalities of the ocular surface. The aim of this study was to explore the effect of sodium hyaluronate-containing eye drops on the ocular surface of patients with dry eye during long term treatment. Methods: A randomised double blind study was undertaken in 86 patients with medium to severe dry eye (that is, rose bengal and/or fluorescein test score of at least 3, tear film break up time <10 seconds, or Schirmers test <5.5 mm). Patients were treated with either preservative-free sodium hyaluronate or saline for 3 months at a dose of one drop 4–8 times a day. Bulbar impression cytology, slit lamp examinations, and subjective symptoms were evaluated after 1, 2, and 3 months. Impression cytology was considered the primary efficacy parameter of the study. Results: The efficacy analysis was performed on a total of 44 patients who were able to fully adhere to the protocol. After 3 months of treatment sodium hyaluronate improved impression cytology score (p = 0.024 v baseline). At the same time also the difference with respect to placebo was statistically significant (p = 0.036). Study medication was well tolerated and no treatment related adverse events occurred during the study. Conclusions: Sodium hyaluronate may effectively improve ocular surface damage associated with dry eye syndrome.

ASPB10 insulin induction of increased mitogenic responses and phenotypic changes in human breast epithelial cells: evidence for enhanced interactions with the insulin-like growth factor-I receptor.

The human insulin analogue ASPB10 has been reported to have increased affinity for the insulin receptor and to cause breast cancer in female rats. In the study reported here, we investigated whether ASPB10 has an increased mitogenic potency and induces a transformed phenotype in cultured human breast cells. In both MCF‐10 cells (a non‐malignant human breast line) and MCF‐7 cells (a human breast cancer cell line), ASPB10 was approximately twofold more potent than insulin in competing for 125I‐insulin binding but sevenfold to tenfold more potent than insulin in competing for 125I‐insulin‐like growth factor (IGF)‐I binding. In addition, ASPB10 was twofold more potent than insulin in stimulating insulin receptor autophosphorylation but significantly more potent in stimulating IGF‐I receptor autophosphorylation in both cell lines. Moreover, ASPB10 was approximately sevenfold more potent than insulin in stimulating the growth of MCF‐10 and MCF‐7 cells. This increased mitogenic effect of ASPB10 was significantly inhibited (but not abolished) when cells were cultured in the presence of α‐IR3, a monoclonal antibody to the IGF‐I receptor. ASPB10, but not insulin, caused phenotypic changes (focus formation) in MCF‐10 cells. Neither agent caused colony formation in soft agar in MCF‐10 cells, but ASPB10 was more potent than insulin in stimulating colony formation in MCF‐7 cells. These observations indicate that in human breast cells, ASPB10 has enhanced mitogenic effects and induces phenotypic changes as a consequence of its activation of both insulin and IGF‐I receptors. Mol. Carcinog. 18:19–25, 1997.

Defects in Insulin-Receptor Internalization and Processing in Monocytes of Obese Subjects and Obese NIDDM Patients

We investigated intracellular processing of the insulin-receptor complex in monocytes from 12 healthy control subjects, 11 obese nondiabetic subjects, and 13 obese patients with non-insulin-dependent diabetes mellitus (NIDDM) by measuring receptor internalization, recovery of cell-surface insulin binding after receptor internalization, and the release of intracellular intact insulin (insulin retroendocytosis). When monocytes from the three groups of subjects were exposed to 100 nM unlabeled insulin for 30 min at 37°C, the subsequent cell-surface 125I-labeled insulin binding was reduced, but the total number of insulin receptors, measured by radioimmunoassay, was not changed. These findings indicate a redistribution of insulin receptors from the surface to the cell interior. Insulin-receptor internalization was significantly lower in monocytes of obese NIDDM patients (mean ± SE 17.8 ± 4.7%) than in obese subjects and healthy control subjects (33.5 ± 4.5%, P < .05, and 34.4 ± 3.7%, P < .02, respectively). Moreover, in downregulated cells, a complete recovery of the initial insulin binding was observed in control subjects but not in obese NIDDM patients or obese nondiabetic subjects. The release of internalized insulin was also reduced in obese NIDDM patients and obese subjects (f1/2 = 49.0 ± 2.4 min, P < .02; 47.4 ± 5.7 min, P < .05; and 32.9 ± 3.8 in NIDDM patients, obese subjects, and control subjects, respectively). In the radioactivity released from monocytes of obese subjects and obese NIDDM patients, the percentage of intact insulin was higher (P < .05) than in control subjects, suggesting reduced intracellular insulin degradation in obese subjects and obese NIDDM patients. This study indicates that insulin-resistant obese subjects and obese NIDDM patients have multiple postbinding defects of the insulin-receptor intracellular processing. Among these defects, decreased insulin-receptor internalization is specifically associated with diabetic patients.

Comparison of Hypotonic and Isotonic Solutions Containing Sodium Hyaluronate on the Symptomatic Treatment of Dry Eye Patients

This study was designed to compare the efficacy of two artificial tears both containing hyaluronic acid but differing in their osmolarity. A multicentric double-masked, crossover clinical trial was performed in which 158 subjects were randomized to receive either hypotonic or isotonic artificial tears up to 6 times a day. Both treatments were effective in improving signs and symptoms to a similar extent. No adverse events were reported. It was concluded that hypotonic and isotonic eye drops are comparable for the symptomatic treatment of patients suffering from dry eye syndrome.

Insulin Receptor: What Role in Breast Cancer?

It is commonly believed that the insulin receptor mainly mediates the metabolic effects of insulin, whereas the closely related IGF-I receptor is considered a major factor for the regulation of cell proliferation. Experimental and epidemiological evidence indicates, however, that insulin and insulin receptors may play an important role in breast cancer. This article reviews evidence indicating that (a) insulin receptors are overexpressed in human breast cancer, (b) insulin stimulates growth in breast cancer cells, (c) cells transfected with human insulin receptor may acquire a ligand-dependent transformed phenotype, and (d) breast cancer is associated with insulin resistance and hyperinsulinemia. These findings may open new possibilities in breast cancer prevention, prognosis assessment, and therapy. (Trends Endocrinol Metab 1997; 8:306-312). (c) 1997, Elsevier Science Inc.

Structural and functional studies of insulin receptors in human breast cancer

SummaryWe characterized the structure and the function of insulin receptors isolated from 10 human breast cancer specimens. We observed that the insulin receptor content, as determined by a specific radioimmunoassay, was four fold increased in human breast cancer tissue when compared to normal breast tissues. In both cancer and normal breast tissues, insulin receptor mRNA consisted of two major species of approximately 11.0 and 8.5 kilobases. The size of the insulin receptor alpha subunit was determined by125I-insulin cross-linking followed by immunoprecipitation and polyacrylamide gel electrophoresis; a value of 135 kDa was observed for receptors from both breast cancer and normal breast tissues. The functional binding ability of insulin receptors from cancer tissues was slightly lower as compared to normal tissue derived insulin receptor (% B/T= 2.22±0.50 per ng of insulin receptor as determined by radioimmunoassay vs. 2.96±0.49, mean±S.E.M.). The concentration of insulin that caused half maximal inhibition of125I-insulin binding was very similar for both cancer and normal breast receptors (80pM).The size of the insulin receptor beta subunit as determined by receptor autophosphorylation was 95kDa. Basal and maximal insulin (100nM) stimulated receptor tyrosine kinase activity, in terms of both receptor autophosphorylation and phosphorylation of an exogenous substrate, was similar in malignant and normal breast tissue derived insulin receptor. Also, a very similar insulin stimulated Km value for ATP was showed by the tyrosine kinase of insulin receptors from breast cancer and normal breast tissue (11.1 and 10.8µM ATP, respectively). However, in insulin receptors from breast cancer tissue the average tyrosine kinase sensitivity to insulin, as calculated on the exogenous substrate, was higher, although not significantly, with respect to normal breast tissue (ED50 at 0.28±0.09 and 1.08±0.33 nM insulin, respectively). A similarly different sensitivity to insulin was observed also for receptor autophosphorylation.In conclusion, this study demonstrates that breast cancer tissues have an increased number of structurally and functionally normal insulin receptors. In some breast cancer tissues, however, the sensitivity of the receptor tyrosine kinase activity to insulin is greatly increased. These data suggest that, in vivo, the mitogenic effect of insulin may play a role in the biology of certain breast cancers.

Treatment of acute bacterial conjunctivitis with topical netilmicin

Purpose. This study compares the clinical and microbiologic value of topical netilmicin with that of gentamicin in the treatment of acute bacterial conjunctivitis. Methods. A double-blind, randomized, prospective, controlled study was performed in 209 patients. One to two drop(s) of either antibiotic was applied to the affected eye(s) four times a day for up to 10 days. Patients were examined at the time of diagnosis and after 3, 5, and 10 days. Clinical efficacy was measured as the cumulative sum score (CSS) of the key signs and symptoms of acute bacterial ocular infection. Sensitivity/resistance was evaluated using the disk diffusion method. Results. Drug efficacy assessment was restricted only to patients with positive baseline culture results (n = 121). Of the isolated organisms, 96.9% were sensitive to netilmicin, whereas only 75.0% were sensitive to gentamicin (p = 0.00001). Netilmicin provided a broad-spectrum coverage comparable with that of ciprofloxacin, ofloxacin, and norfloxacin. Netilmicin also was more effective than gentamicin in eradicating infections (p = 0.001 at day 5 and p = 0.037 at day 10) and in ameliorating the CSS (p = 0.037 at day 3, p = 0.001 at both day 5 and day 10). Only minor adverse events occurred in patients treated with either netilmicin or gentamicin. Conclusions. This study demonstrates that netilmicin is a safe and effective antibiotic that can be used as first-line therapy for the treatment of acute bacterial conjunctivitis.

Insulin-stimulated cell growth in insulin receptor substrate-1-deficient ZR-75-1 cells is mediated by a phosphatidylinositol-3-kinase-independent pathway.

In many human breast cancers and cultured cell lines, insulin receptor expression is elevated, and insulin, via its own insulin receptor, can stimulate cell growth. It has recently been demonstrated that the enzyme phosphatidylinositol‐3‐kinase (PI3‐K) mediates various aspects of insulin receptor signaling including cell growth. In order to understand the mechanisms for insulin‐stimulated cell growth in human breast cancer, we measured insulin‐stimulable PI3‐K activity in a non‐transformed breast epithelial cell line, MCF‐10A, and in two malignantly transformed cell lines, ZR‐75‐1 and MDA‐MB157. All three cell lines express comparable amounts of insulin receptors whose tyrosine autophosphorylation is increased by insulin, and in these cell lines insulin stimulates growth. In MDA‐MB157 and MCF‐10A cells, insulin stimulated PI3‐K activity three‐ to fourfold. In ZR‐75‐1 cells, however, insulin did not stimulate PI3‐K activity. In ZR‐75‐1 cells PI3‐K protein was present, and its activity was stimulated by epidermal growth factor, suggesting that there might be a defect in insulin receptor signaling upstream of PI3‐K and downstream of the insulin receptor. Next, we studied insulin receptor substrate‐1 (IRS‐1), a major endogenous substrate for the insulin receptor which, when tyrosine is phosphorylated by the insulin receptor, interacts with and activates PI3‐K. In ZR‐75‐1 cells, there were reduced levels of protein for IRS‐1. In these cells, both Shc tyrosine phosphorylation and mitogen‐activated protein kinase (MAP‐K) activity were increased by the insulin receptor (indicating that the p21ras pathway may account for insulin‐stimulated cell growth in ZR‐75‐1 cells).

Topical naproxen sodium for inhibition of miosis during cataract surgery. Prospective, randomized clinical trials

Purpose To assess corneal penetration of naproxen sodium and its efficacy in maintaining intraoperative mydriasis during cataract surgery.Methods Two double blind studies have been performed comparing the efficacy of naproxen ophthalmic solution to that of placebo or diclofenac in inhibiting pre-operative miosis. Study No. 1 was a placebo-controlled study and involved 194 patients undergoing extracapsular cataract extraction. Study No. 2 was an active-controlled study (vs diclofenac) concerning 214 patients undergoing phacoemulsification. In both studies treatment started the day before surgery. A balanced salt solution containing adrenaline was used in all patients. Pupil size was measured prior to the corneal section and at the end of surgery. An aqueous humor sample was taken immediately before corneal incision in a subset of 20 patients to measure naproxen aqueous concentration.Results In both studies the pupillary diameter decreased during surgery within each treatment group in a statistically significant manner (P < 0.001). Naproxen was more effective than placebo (P < 0.01) and as effective as diclofenac in controlling pupil diameter regression during cataract. Mean concentration level of naproxen in the aqueous humor was 372.3 ng/ml.Conclusions Naproxen sodium ophthalmic solution penetrates the cornea and it is effective in maintaining intraoperative mydriasis.

Dexamethasone-netilmicin : a new ophthalmic steroid-antibiotic combination. Efficacy and safety after cataract surgery

PurposeThe purpose of this study was to evaluate both efficacy and safety of a new ophthalmic steroid–antibiotic fixed combination containing dexamethasone and netilmicin in the postsurgical management of cataract surgery.MethodsIn total, 223 patients were randomly treated with dexamethasone 1 mg/ml plus netilmicin 3 mg/ml (n=148), or dexamethasone 1 mg/ml plus tobramycin 3 mg/ml (n=75, TOBRADEX®) four times in a day for 7±1 days starting immediately after surgery. Efficacy (anterior chamber (AC) inflammation, conjunctival hyperaemia, corneal and lid oedema, ocular infection, pain, photophobia and tearing) and safety (burning, stinging, blurred vision, intraocular pressure, and visual acuity) were analysed in the operated eye after 1 and 7±1 days. A follow-up visit was performed at day 14±2. The extent of AC inflammation, measured by slit-lamp according to a standard scoring system, was used as primary efficacy parameter.ResultsAt the primary end point (day 7) both fixed combinations were equally effective in reducing postoperative inflammation. The safety profile of the dexamethasone/netilmicin combination was excellent with no evidence of poor local tolerance or adverse reaction.ConclusionsA new fixed combination of dexamethasone and netilmicin was effective and safe in controlling ocular inflammation after cataract surgery.