Grb2 downregulation leads to Akt inactivation in heregulin-stimulated and ErbB2-overexpressing breast cancer cells

ErbB2 can be activated by its own overexpression or be transactivated by the heregulin polypeptide growth factor. Activation of ErbB2 leads to breast cancer cell proliferation, presumably by inducing the activation of extracellular signal-regulated kinases 1,2 (Erk1,2) and Akt. We have previously reported that the growth factor receptor bound protein-2 (Grb2) is required for the proliferation of ErbB2-overexpressing breast cancer cells. We investigated here whether Grb2 protein plays a role in heregulin-stimulated proliferation. Grb2 protein inhibition led to growth inhibition of heregulin-stimulated breast cancer cells, but not Erk1,2 inactivation. These findings are similar to our earlier observations in ErbB2-overexpressing cells. Since Akt can also be activated by heregulin, the effects of Grb2 inhibition on Akt were examined. Akt was inactivated following Grb2 downregulation in heregulin-stimulated breast cancer cells. We then examined the effects of Grb2 downregulation on Akt in ErbB2-overexpressing cells in the absence of heregulin. Similar to heregulin-stimulated cells, Grb2 inhibition also led to Akt inactivation in ErbB2-overexpressing breast cancer cells. Our results indicate that the activation of ErbB2 by heregulin or by its overexpression requires Grb2 to stimulate the Akt pathway to propagate mitogenic signals.

Effect of mitomycin-C on posterior capsule opacification in rabbit eyes

PURPOSE

To determine whether mitomycin-C can inhibit posterior capsule opacification (PCO) without causing ocular toxicity.

SETTING

Yonsei Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.

METHODS

Mitomycin-C dissolved in sodium hyaluronate (0.2 cc of 0.2 mg/mL) was injected into the empty capsular bag for 3 minutes after endocapsular phacoemulsification in rabbit eyes. Three months after surgery, the obstruction rate of visible light caused by PCO was measured using an optical power meter.

RESULTS

The mean obstruction rate of visible light was 81.0% +/- 8.3% (SD) in the control group in which sodium hyaluronate without mitomycin-C was used, 30.5% +/- 10.1% in the group in which mitomycin-C was dissolved in sodium hyaluronate, and 71.9% +/- 6.8% in the group in which mitomycin-C was dissolved in a balanced salt solution. Statistically significant differences were found among all 3 groups.

CONCLUSIONS

Our results suggest that the application of mitomycin-C dissolved in sodium hyaluronate effectively reduces PCO in rabbit eyes.

Scleral fixation technique using 2 corneal tunnels for a dislocated intraocular lens

Several techniques are used to reposition dislocated intraocular lenses (IOLs). Most place a suture loop around the end of the haptic. However, in cases of a dislocated capsular bag containing the IOL, a dislocated IOL with a large haptic, or a miotic pupil, it is not easy to see the haptic ends to place the suture loop. We describe a scleral fixation technique that uses 2 corneal tunnels. A double-armed 10-0 polypropylene suture loop can be introduced through 1 corneal tunnel and placed around any accessible part of the haptic with the help of a bent 26 gauge needle. This modified technique is an easy and effective way to reposition the IOL.

Multiple peripheral nerve compressions related to malignantly transformed hereditary multiple exostoses

Autosomal dominantly transmitted hereditary multiple exostoses is an uncommon disorder consisting of multiple projections of bone capped by cartilage. The lesions are most numerous in the metaphyses of long bones but may appear on flat bones. Sarcomatous transformation occurs in 1-25% of patients. We report a 33-year-old man with sciatica, previously diagnosed as hereditary multiple exostoses, presenting with multiple peripheral nerve compressions. Electrodiagnostic studies showed profound axon-loss multiple neuropathies involving the sciatic, superior gluteal, and inferior gluteal nerves. Magnetic resonance imaging of the left pelvis showed a large mass in the sacral area that was suggestive of a chondrosarcoma. An open intralesional excision biopsy confirmed chondrosarcoma transformed from chondromatosis. Excision of the lesion was effective in eliminating the impingement of nerves and retarding progressive osseous growth. We suggest that malignant transformation be suspected in cases with focal compression neuropathy of patients known to have multiple exostoses. Osteochondroma as a possible cause for compression neuropathy is discussed.

Effect of 0.2% brimonidine in preventing intraocular pressure elevation after Nd:YAG laser posterior capsulotomy

BACKGROUND AND OBJECTIVE

To determine the prophylactic effect of 0.2% brimonidine in reducing the elevated intraocular pressure (IOP) in patients undergoing Nd:YAG laser posterior capsulotomy.

PATIENTS AND METHODS

The 81 patients (81 eyes), who underwent Nd:YAG laser posterior capsulotomy, were allocated to two treatment groups. One drop of 0.2% brimonidine or vehicle was instilled 1 hour preoperatively and one drop immediately after capsulotomy. IOPs were measured preoperatively and 1, 2, 3, and 24 hours postoperatively.

RESULTS

Intraocular pressure decreased from the baseline in the brimonidine group by the third postoperative hour (P<0.05), while the vehicle group exhibited an increase. Intraocular pressure elevations of 5 mm Hg or greater occurred in 7.3% (3/41) in the brimonidine group compared to 20.0% (8/40) in the vehicle group. IOP elevations of 10 mm Hg or greater occurred in 2.4% (1/41) in the brimonidine group compared to 7.5% (3/40) in the vehicle group.

CONCLUSIONS

One drop of 0.2% brimonidine instilled 1 hour preoperatively and immediately after capsulotomy was found to be efficacious and safe in preventing IOP elevations that frequently follow Nd:YAG laser posterior capsulotomy.

Nocardia Keratitis After Traumatic Detachment of a Laser in situ Keratomileusis Flap

PURPOSE

Nocardia are gram-positive bacteria existing ubiquitously in the environment; they can cause keratitis. Nocardia asteroides keratitis occurred in the interface between the stromal bed and flap after traumatic detachment of the flap 4 months after an initially uncomplicated laser in situ keratomileusis (LASIK) procedure.

METHODS

Nocardia asteroides keratitis was confirmed by culture. Therapy included topical and oral trimethoprim-sulfamethoxazole.

RESULTS

Thirteen months after the trauma, the patient's spectacle-corrected visual acuity was 20/20 with a manifest refraction of -2.25 -1.00 x 30 degrees.

CONCLUSIONS

The immediate steps of management consisting of surgically lifting the corneal flap, rapid microbial identification, and proper treatment with specific antibiotics resulted in the successful treatment of Nocardia asteroides keratitis in a traumatized eye after LASIK.

The effective concentration and exposure time of mitomycin-C for the inhibition of lens epithelial cell proliferation in rabbit eyes

The proliferation of residual lens epithelial cells following cataract surgery is assumed to be a major cause of posterior capsular opacification. To assess the efficacy of mitomycin-C in preventing posterior capsular opacification, we determined the effective concentration and exposure time of mitomycin-C in inhibiting rabbit lens epithelial cell proliferation. The fourth-passaged rabbit lens epithelial cells were maintained for one day and then exposed to mitomycin-C for 1, 2, 3, and 5 minutes, respectively. There were 9 different plating concentrations of mitomycin-C with two-fold serial dilution. The maintenance of the phenotypic properties of lens epithelial cells was confirmed by continuous transcription of lambda-crystalline mRNA determined by reverse transcription-polymerase chain reaction and the polymorphism of the restriction fragment. Cell proliferation was assayed with 3H-thymidine incorporation into DNA. The fourth-passaged cells maintained the expression of lambda-crystalline mRNA, suggesting that they are phenotypically authentic lens epithelial cells. The effective concentrations and exposure time of mitomycin-C were 0.1 mg/ml for 1 minute and 2 minutes, and 0.025 mg/ml for 2 minutes. By these results, we postulated that mitomycin-C at relatively short incubation times could be clinically used for prevention of posterior capsular opacification after cataract surgery.

The effect of the haptic portion of intraocular lens on the development of posterior capsular opacification in rabbit

Using a white rabbit model, the effect of the haptic portion of the intraocular lens (IOL) and intracapsular ring on the development of posterior capsular opacification (PCO) after extracapsular cataract extraction (ECCE) with phacoemulsification was studied. Implantation of both the intracapsular ring and IOL developed less PCO than implantation of the IOL alone. ECCE followed by implantation of the intracapsular ring alone also developed less PCO than ECCE alone. Through this experimental work in a rabbit model, it could be conceived that the haptic portion of IOL and the intracapsular ring can prevent the development of PCO.

Degradation of chloronitrobenzenes by a coculture of Pseudomonas putida and a Rhodococcus sp

A single microorganism able to mineralize chloronitrobenzenes (CNBs) has not been reported, and degradation of CNBs by coculture of two microbial strains was attempted. Pseudomonas putida HS12 was first isolated by analogue enrichment culture using nitrobenzene (NB) as the substrate, and this strain was observed to possess a partial reductive pathway for the degradation of NB. From high-performance liquid chromatography-mass spectrometry and 1H nuclear magnetic resonance analyses, NB-grown cells of P. putida HS12 were found to convert 3- and 4-CNBs to the corresponding 5- and 4-chloro-2-hydroxyacetanilides, respectively, by partial reduction and subsequent acetylation. For the degradation of CNBs, Rhodococcus sp. strain HS51, which degrades 4- and 5-chloro-2-hydroxyacetanilides, was isolated and combined with P. putida HS12 to give a coculture. This coculture was confirmed to mineralize 3- and 4-CNBs in the presence of an additional carbon source. A degradation pathway for 3- and 4-CNBs by the two isolated strains was also proposed.

Recanalization of obstructed Tenckhoff peritoneal dialysis catheter: wire/stylet manipulation combined with endoluminal electrocauterization

We report the results of fluoroscopically guided wire/stylet manipulation combined with endoluminal electrocauterization in seven patients with obstructed Tenckhoff peritoneal dialysis catheters. In preparation for clinical application, electrocauterization was performed using a stone basket to recanalize surgically removed Tenckhoff catheters obstructed with omental fat ingrowing through the side holes. All ingrowing omental fat was removed easily by electrocauterization with the rotating movement of a stone basket. The technique was then applied in vivo in seven cases with ingrowing omental fat and malpositioned catheter; six (86%) were successfully recanalized. Among those six cases with initial success, four maintained good catheter function with durable patency (mean 261.3 days). No significant complication was noted.

Ideal size of an intraocular lens for capsular bag fixation

PURPOSE

To determine the ideal size of an intraocular lens (IOL) for proper capsular bag fixation in different sizes of evacuated capsular bags.

SETTING

Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea, and Storm Eye Institute Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Fifteen eyes obtained post-mortem were divided by crystalline lens size into three groups. Intraocular lenses of five different sizes were implanted in each capsular bag. The arc of contact between the haptics and capsular equator and the capsular bag distortion with each IOL were measured and compared using posterior-view analysis.

RESULTS

The arc of contact was directly proportional to the IOL size and inversely related to the lens size. The smallest arc of contact was 2.0 mm with the smallest IOL implanted in the largest lens group. The maximum capsular bag distortion was 2.6 mm in the case of the largest IOL implantation in the smallest lens group.

CONCLUSION

Implanting an IOL smaller than 12.5 mm in a large capsular bag can result in unstable fixation, while implanting an IOL larger than 12.5 mm in a small capsular bag can result in excessive stretching and distortion of the capsular bag and surrounding zonules.

Analysis of zonular-free zone and lens size in relation to axial length of eye with age

PURPOSE

To evaluate the anatomical relationships of the zonular-free zone (ZFZ) of the anterior capsule and crystalline lens diameter in relation to the axial length of the eye with age.

SETTING

Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea, and Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHOD

Various ocular structures in 122 eyes obtained post-mortem were measured without prior preparation. The correlation between age, anterior-posterior (A-P) length and globe size, and diameters of the cornea, crystalline lens, and ZFZ were analyzed.

RESULTS

The average A-P globe length, and corneal, lens, and ZFZ diameters were 24.48, 11.67, 9.65, and 6.93 mm, respectively. There was no significant relationship between A-P length and globe size and corneal diameter in different age groups. The ZFZ size varied negligibly among age groups. There was a statistically significant correlation between lens diameter and age (correlation coefficient = 0.2647; P < .01) and lens diameter and A-P globe length (correlation coefficient = 0.3183; P < .001).

CONCLUSIONS

When choosing an intraocular lens, one should consider the patient's age and the A-P globe length. Six eyes (5%) showed unusual anterior insertion of zonular attachment, which reminds us to be prudent with a large paracentral capsulorhexis.

Anterior shift of zonular insertion onto the anterior surface of human crystalline lens with age

OBJECTIVE

This study aimed to investigate the age-related changes in the position of zonular insertion onto the anterior lens capsule.

DESIGN

The study design was an experimental cadaveric eye study.

PARTICIPANTS

Two hundred twenty-three cadaveric eyes (range, 16-100 years old) from eye banks in the United States were studied.

INTERVENTION

The zonular insertion onto the anterior capsule was detected using a modified posterior photographic technique.

MAIN OUTCOME MEASURES

The distances from the anterior zonular insertion (AZI) to the lens equator and to the ciliary sulcus, size of zonular-free zone, lens diameter, ciliary sulcus diameter, and axial length of the globe were measured.

RESULTS

Multiple regression analysis showed that age, lens diameter, and axial length of the globe had significant correlations with AZI (r2 = 0.748), among which age showed the highest relevance with AZI. Multiple regression equation was expressed as AZI = (0.0079 x age) + (0.202 x lens diameter) - (0.041 x axial length of the globe) + 0.0114. The increase in AZI was accompanied by a decrease in the size of zonular-free zone with age (r = -0.206, P < 0.001).

CONCLUSION

Aging correlates with an increase in the distance from the anterior zonular insertion to the lens equator and a decrease in zonular-free zone.

Homogeneous liposome immunoassay for insulin using phospholipase C from Clostridium perfringens

A new homogeneous liposome immunoassay system was developed in which analyte-phospholipase C conjugates are used instead of complement or melittin. This system was applied for the determination of insulin. Liposomes incorporated with calcein as a marker were prepared by the reverse-phase evaporation method. The lysis of liposomes was determined by measuring the fluorescence intensity of calcein released from liposomes and it was increased with increasing concentration of phospholipase C. Insulin was conjugated to phospholipase C by a three-step procedure with hetero-bifunctional crosslinking reagents, succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate and 3-(2-pyridyldithio)propionic acid N-hydroxysuccinimide ester. The lytic activity of phospholipase C was not affected by the reaction for conjugation. Both p-nitrophenylphosphatidylcholine hydrolytic activity and liposome lytic activity of insulin-phospholipase C conjugate were inhibited in the presence of insulin antiserum. However, lower concentration of conjugate and shorter incubation time were required when liposomes were used in the inhibition study. The antibody inhibition of conjugate-induced lysis could be reversed by addition of a competing amount of free insulin. The standard calibration curve was obtained in the range between 4 and 130 microIU/ml (r = 0.994). The detection limit (8 microIU/ml) was comparable with those of conventional heterogeneous enzyme immunoassays. This new assay approach offers a simple, sensitive, and inexpensive testing procedure for determining ultratrace amounts of bioactive substances.

[Anatomical evaluation of the anterior capsular zonular free zone in the human crystalline lens (age range, 50 approximately 100 years)]

It is important to determine the anterior capsular zonular free zone (ZFZ) in order to minimize the risk of zonular disinsertion. From this point of view the size of the ZFZ of normal suspended lenses was directly measured in 199 human eyes obtained postmortem. The cornea was completely excised and the iris removed to allow clear visualization of the anterior surface of the lens to the equator. After measuring lens diameter with a caliper, a 4 mm continuous curvilinear capsulorhexis was performed, and lens substrate was completely removed by phacoemulsification. Care was taken to minimize trauma to the zonules during surgery. The anterior insertion of the zonules was identified at high power magnification; the size of the ZFZ was measured with a caliper. The mean age was 75.5 +/- 10.3 (+/-SD) years (age range, 50 approximately 100 years). The mean diameter of the lenses was 9.72 +/- 0.31 mm. The mean diameter of the ZFZ was 6.83 +/- 0.35 mm. Statistical analysis revealed no significant correlation between the size of the ZFZ and age, or between the size of the ZFZ and lens diameter. The present study indicates that the size of the ZFZ was constant regardless of age or lens diameter.

Role of protein kinase C isozymes in activation of human immunodeficiency virus type 1 in chronically infected promonocytic cells: evidence against a role of PKC beta 1

Protein kinase C (PKC) plays an important role in activation of human immunodeficiency virus type 1 (HIV-1). Because of a molecular and biochemical heterogeneity of PKC, we have studied the effects of PKC isozymes in HIV-1 activation in a latently infected promonocytic cell line, U1, using various PKC isozyme agonists. 12-Deoxyphorbol 13-phenylacetate (dPP), an agonist of both Ca(++)-dependent and Ca(++)-independent isozymes, and thymeleatoxin (TT), an agonist of Ca(++)-dependent PKC isozymes, induced HIV-1 production at 10 nM with increase in a concentration dependent manner, whereas 12-deoxyphorbol 13-phenylacetate 20-acetate (dPPA), an PKC beta I isozyme agonist, did not induce viral production at 100 nM. We verified that dPPA induced translocation of PKC beta isozyme with the isozyme-specific monoclonal antibody using flow cytometry. This study demonstrates that activation of PKC isozymes leads to an induction of latent HIV-1 in U1 cells whereas PKC beta I isozyme may not be important.

Liposome immunoassay (LIA) with antigen-coupled liposomes containing alkaline phosphatase

Immunoliposomes were prepared and their immunoassay applications investigated. Liposomes were prepared from cholesterol and phospholipids including maleimidobenzoylphosphatidylethanolamine (MBPE) for conjunction with thiol-containing antigens. Alkaline phosphatase (APase) was entrapped in the liposome and BSA, the antigen, was modified by reaction with 3-(2-pyridyl-dithio)propionyl N-hydroxysuccinimide ester (SPDP) to introduce thiol groups for efficient coupling. BSA-coupled liposomes (immunoliposomes) were incubated with anti-BSA serum, complement, and then with APase substrate. The amount of coupled BSA was affected by the reaction time, the composition of the liposome and the BSA concentration in the reactant. The amount of enzyme released from immunoliposomes as a final result of the immunoreaction increased with increasing concentrations of complement and antibody. The liposome immunoassay offers a relatively rapid and simple testing procedure to quantitatively or qualitatively determine the presence or absence of antibodies, or antigenic materials for diagnostic purposes.

Water resource development and prevention of malaria

The construction of dams across the mouths of major tidal rivers in the development of the Kranji Reservoir, Western Catchments Scheme and the Sungei Seletar Reservoir in Singapore created suitable environmental conditions for the propagation of anopheline brackish-water breeders. The employment of foreign contract workers from malarious areas for the projects further increased the potential risk of malaria transmission. However, constant vigilance and environmental management aimed at the permanent elimination of vector breeding habitats, supplemented with chemical control and anti-parasite measures successfully prevented the reintroduction of malaria in these highly receptive and vulnerable areas.