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At least 469 records · Page 26Linked to original sources
PubMed2002

Insulin increases the sensitivity of tumors to irradiation: involvement of an increase in tumor oxygenation mediated by a nitric oxide-dependent decrease of the tumor cells oxygen consumption.

The effects of insulin on tumor oxygenation, perfusion, oxygen consumption,and radiation sensitivity were studied on two different mouse tumor models (TLT, a liver tumor, and FSAII, a fibrosarcoma). Anesthetized mice were infused with insulin i.v. at a rate of 16 milliUnits/kg/min for 25 min. Local tumor oxygenation measurements were carried out using two independent techniques: electron paramagnetic resonance oximetry and a fiber-optic device (OxyLite). Two complementary techniques were also used to assess the blood flow inside the tumor: a laser Doppler system (OxyFlo) and contrast-enhanced magnetic resonance imaging. The oxygen consumption rate of tumor cells after in vivo insulin infusion was measured using high frequency electron paramagnetic resonance oximetry. To know if insulin was able to enhance radiation-induced tumor regrowth delay, tumor-bearing mice were treated with 16 Gy of 250 kV radiation dose after insulin infusion. We provide evidence that insulin increases the local pressure of oxygen of tumors (from 0-3 mm Hg to 8-11 mm Hg) as well as the tumor response to irradiation (increasing regrowth delay by a factor of 2.11). We found that the insulin-induced increase of tumor pressure of oxygen: (a) is not caused by an increase in the tumor blood flow, which is even decreased after insulin infusion; (b) is because of a decrease in the tumor cell oxygen consumption (in vivo insulin consumed oxygen three times slower than control cells); and (c) is inhibited by a nitric oxide (NO) synthase inhibitor, Nomega-nitro-L-arginine methyl ester, when injected i.p. at 15 micromol/kg(-1), 1 h before insulin infusion. We demonstrate by immunoblotting that the NO pathway involves a phosphorylation of endothelial NO synthase and showed a concomitant increase in the cyclic GMP tumor level. These findings provide unique insights into biological processes in tumors, new possible management for treating cancer patients, and raise major questions about the role of insulin secretion (fasting status and diabetes) in the clinical response of tumors to radiation therapy.

Animals↗
PubMedDate not supplied

Assessment of educational services available to blind and low vision school children in Lagos, Nigeria.

A descriptive study to assess the educational services available to children attending the Pacelli School for the Blind in Lagos, Nigeria. A standardised methodology was used with structured and semi-structured questionnaires. Observations were also made in some areas. Of the 26 children aged 10-15 years who were identified as having low vision, 15 (57.7%) of them had significant improvement in distance and near vision after refraction while one third (31%) had improvement in their reading with low power magnifying lenses. All except 4 (25%) teachers were well educated but none seemed to have appreciable knowledge about the teaching of low vision children as all these children were taught Braille like their blind peers. While educational facilities available were reasonably adequate for blind children, no visual aids were available for low vision children. It is recommended that appropriate educational facilities, optical and non-optical devices should also be provided particularly for low vision children to enable them achieve their optimal potential in life.

Adolescent↗
PubMed2002

Vision readiness in Operation Restore Hope.

Ensuring that our forces are vision ready for their mission is essential on today's battlefield. Vision readiness considers optical readiness (appropriate correcting eyewear) and visual readiness (adequate job-required visual acuity). A study of vision readiness among deploying personnel for Operation Restore Hope in Bosnia from December 1995 to September 1997 was conducted at Fort Benning, Georgia. Of the 10,063 personnel screened, 3,554 (35.3%) were not optically ready for deployment and 406 (4.0%) were not visually ready for deployment. Analyses indicated a statistically significant difference between the active duty and reserve components in optical and visual readiness. A more effective vision readiness process should be implemented before deployment to ensure that all personnel are deployment ready. Optometry personnel, commanders, and deploying soldiers, sailors, airmen, and marines must take a more active role in ensuring that our forces have the appropriate visual acuity and optical devices to deploy.

Contact Lenses↗
PubMed2003

Visual acuity, optical, and eye health readiness in the military.

Optimum vision readiness is essential on today's technologically advanced battlefield. A vision readiness screening of 4,825 active duty personnel at 13 Department of Defense sites from September through December 1997 revealed 4,021 (83.3%) not vision ready: 500 (10.4%) had substandard visual acuity, 1,249 (25.9%) had deficient optical devices, and 3,562 (73.8%) had eye health-related deficiencies. This suggests a more effective ongoing vision readiness process should be implemented to ensure all personnel are vision ready prior to deployment.

Contact Lenses↗
PubMed2003

[Experimental therapeutic modalities for retinitis pigmentosa].

Retinitis Pigmentosa (RP) is a heterogeneous group of inherited diseases that cause retinal degeneration, often leading to blindness. Over the last decade, the advent of molecular biological techniques has greatly improved our understanding of the genetic and molecular processes underlying these diseases. This has prompted research efforts aimed at the development of novel therapeutic modalities for RP, and the purpose of this review is to present current trends in this field. In this first of two parts, advances in gene therapy, the use of neurotrophic growth factors, and attempts to alter disease progression by vitamins and nutritional modification are discussed. Experimental treatments involving surgical intervention will be addressed in a future, second part of this review that will include the topics of retinal and retinal pigment epithelium transplantation, the potential use of stem cells to replace degenerating retinal cells, and the development of "artificial vision" using electro-optical devices. The encouraging progress made in these various experimental directions lends hope that efficient treatment for at least some of the patients suffering from these blinding diseases is within sight.

Disease Progression↗
PubMed2003

[Phakic IOL].

Refractive errors can be corrected by three different means, as follows: optical devices, corneal refractive surgery and intraocular procedures. Each intraocular procedure has its advantages and disadvantages. In this paper the authors present the nowdays state of refractive phakic IOL's.

Humans↗
PubMed2003

Interrogating androgen receptor function in recurrent prostate cancer.

The early androgen-dependent (AD) phase of prostate cancer is dependent on the androgen receptor (AR). However, it is unclear whether AR is fully functional in recurrent prostate cancer after androgen withdrawal. To address this issue we interrogated AR signaling in AD and recurrent prostate cancer xenografts using molecular imaging, chromatin immunoprecipitation, and immunohistochemistry. In the imaging experiments, an adenovirus bearing a two-step transcriptional activation cassette, which amplifies AR-dependent firefly luciferase reporter gene activity, was injected into tumors implanted into severe combined immunodeficiency mice. A charge-coupled device optical imaging system detected the initial loss and then resumption of AR transcriptional activity in D-luciferin-injected mice as tumors transitioned from AD to recurrent growth. The results of chromatin immunoprecipitation and immunohistochemical localization experiments correlated with the Ad two-step transcriptional activation imaging signal. AR localized to the nucleus and bound to the endogenous prostate-specific antigen enhancer in AD tumors but exited the nucleus and dissociated from the enhancer upon castration. However, AR reentered the nucleus and rebound the prostate-specific antigen enhancer as the cancer transitioned into the recurrent phase. Surprisingly, RNA polymerase II and the general factor TFIIB remained bound to the gene throughout the transition. Our data support the concept that AR is fully functional in recurrent cancer and suggest a model by which a poised but largely inactive transcription complex facilitates reactivation by AR at castrate levels of ligand.

Adenoviridae↗
PubMed2003

[Refractive surgery: techniques and reliability].

Refractive surgery modifies anatomic properties of the eye, in order to improve vision without the recourse to optical devices. It includes corneal surgery (radial keratotomy, excimer laser keratectomy), intraocular surgery (artificial lens implantation) and scleral surgery. The level of satisfaction of the patients who have benefit from this surgery is usually high, but is related to the selection of the subjects, which depends on the motivation and also on the default to be corrected. Despite the continuous progress of that surgery, it is not devoid of risks and complications.

Humans↗
PubMed2003

Follow-up study on vision health readiness in the military.

A retrospective study reviewed medical records of military personnel who had participated in a vision readiness study the previous year. The review evaluated (1) the number of personnel who returned for an eye examination (as recommended), (2) the number of dilated eye examinations, (3) the number of optical devices ordered, (4) the number of patients requiring continuing treatment, (5) the types of eye disease in personnel who were classified as nondeployable in the original study, and (6) the relationship between patient vision complaints and the need for spectacles. Analyses revealed 44% of military personnel have never had a comprehensive eye examination. Of these personnel who never had an eye examination, 15% to 26% could improve their vision with spectacles. Finally, even though having an eye examination is important, whether or not the individual has had a comprehensive eye examination should not be a significant criterion for deployment.

Female↗
PubMed2004

[Experimental therapeutic modalities for retinitis pigmentosa].

Retinitis Pigmentosa (RP) is a heterogeneous group of inherited diseases that cause retinal degeneration, often leading to blindness. Over the last decade, significant insights have been obtained into the mechanisms underlying retinal degeneration in RP. This improved understanding of the pathogenesis of RP, combined with advances in molecular and cellular biology methods as well as electro-optical technologies, have contributed to renewed interest and increasing efforts to design novel therapeutic approaches for RP. In the first part of this review (Harefuah, April 2003), we summarized recent developments in the fields of gene therapy for RP, the use of neurotrophic growth factors, and attempts to alter disease progression by vitamins and nutritional modifications. In this second part of the review, retinal and retinal pigment epithelium transplantation, the potential use of stem cells to replace degenerating retinal cells and attempts to develop a retinal prosthesis using electro-optical devices are described. The exciting progress made in these various experimental directions raises hope that slowing or preventing the progression of retinal degeneration in RP patients, and perhaps even partial restoration of visual function in RP, is within reach.

Disease Progression↗
PubMedDate not supplied

In-situ and high-resolution optical observation in local anodic oxidation process using a scanning near-field optical microscope.

Using a local oxidation process with a probe tip of a scanning near-field optical microscope (SNOM), antimony oxide structures with a pattern width of several 100 nm were fabricated on antimony thin films. We also investigated the characteristics of the oxidation process using the transmission mode SNOM. Although slight topographic changes due to oxidation were observed by atomic force microscopy, an increase in transmission due to the phase change of the metal to transparent oxide was observed. The depth of the oxide embedded in the antimony film was estimated from the change of the transmission intensity without destroying the sample. This fabrication method is appropriate for making a prototype of future nano-optical devices and for trimming them in order to optimize their functions on demand.

Journal Article↗
PubMed2005

[Endoscopic subfascial dissection of venous perforants in treatment of venous trophic ulcers of the legs].

Endoscopic subfascial dissection was performed in patients with chronic venous insufficiency of CEAP class 4-6. 76 surgeries were performed in 68 patients. Mean age of the patients was 56 years. The causes of chronic venous insufficiency were varicose (37) and postthrombotic diseases. Trophic ulcers were in 46 patients. Thirty patients underwent earlier various phlebectomies, including Linton's surgery (6 patients). In 33 patients endoscopic subfascial dissection of venous perforants was combined with various phlebectomy, in 37 patients -- with excision of ulcer with following autodermoplasty few days after surgery. Endoscopic subfascial dissection was carried out with special surgical R.Wolf endoscope with 6 mm instrumental canal, and also standard laparoscopic optical devices "Olympus". Complications during surgery were seen in 2 patients: bleeding in subfascial space (1.3%) and perforation of tissues in ulcer zone (1.3%). In postoperative period long (up to 14 days) lymphorrhea and suppuration of surgical wound were in 2 (2.6%) patients. It is concluded that endoscopic approach is optimal for elimination of pathological reflux through venous perforants in complicated forms of chronic venous insufficiency of the lower extremities, including trophic ulcers resistant to treatment.

Adult↗
PubMed1991

Low vision rehabilitation of the albino patient.

From the eye care professional's point of view, the three most common types of albinism are tyrosinase-negative oculocutaneous albinism, tyrosinase-positive oculocutaneous albinism and ocular albinism. Skin and uveal hypopigmentation is variable in this condition depending on the type of albinism. However, all types of albinism lack the necessary uveal pigmentation have subnormal visual acuity. Using low vision rehabilitation techniques such as modifying lighting and providing telescopic optical devices, these patients can experience dramatic improvements in functional visual acuity. This manuscript examines strategic approaches to visual rehabilitation as well as provides a clinical review of the condition.

Albinism, Oculocutaneous↗
PubMed1990

[Surgical correction of corneal astigmatism].

Corneal astigmatism can be treated optically or surgically. First, we try to manage the astigmatism with glasses or contact-lenses. If it cannot be managed successfully with optical devices, a surgical approach may be indicated. Corneal wedge resections and relaxing incisions can be effective. The wedge resection is the more difficult procedure with reasonably predictable results. In recent years corneal relaxing incision has gained popularity because it is a simple technique with fairly rapid visual rehabilitation. However, the correction result is quite unpredictable. We try to evaluate the factor that created the astigmatism. The steep and flat corneal meridian are identified with keratoscopy, and the correction is performed at the end of the corneal meridian causing the astigmatism. The technique and results are discussed.

Astigmatism↗
PubMed1990

Study on a new index of fetal respiratory function: a novel optical analysis of the amniotic fluid by the vacuum-dried infrared attenuated total reflection (ATR) method.

For the purpose of detecting fetal pulmonary maturity with real-time convenience but reliable accuracy, infrared spectrophotometry of amniotic fluid lipids was introduced using our newly developed optical device. The peak areas at the wave number of 1740 cm-1 on the infrared spectra (called "PA1740") were measured in 29 specimens sampled from 29 pregnant women, and compared with the Lecithin/Sphingomyelin (L/S) ratio of the same samples. Statistical analysis revealed that the PA1740 was almost as reliable as the L/S ratio, and these indices illustrated pulmonary immaturity in cases with a PA1740 less than 0.9 and an L/S ratio less than 2.0. PA1740 is absolutely independent of the effect on the concentration of lecithin in the amniotic fluid because of a combination of the vacuum-drying process and the absorbance correction, and can be completed in less than 20 minutes from sampling of the amniotic fluid by a very simple manipulation. In conclusion, the new index, PA1740, will be a more practical method for prediction of the fetal pulmonary maturity than methods such as the well known L/S ratio.

Amniotic Fluid↗