Corneal electrode for recording electroretinograms in rats

The corneal contact lens electrode, because of its convenience, has replaced the cotton-wick electrode for recording electroretinograms from patients and animals such as dogs, rabbits, and cats. The cotton-wick electrode, however, remains popular for rat electroretinogram measurements because small contact lens corneal electrodes that fit rat eyes are difficult to fabricate. We prepared corneal electrodes from disposable needles for use in recording electroretinograms from rats. The electrodes were readily prepared, were inexpensive, and were used successfully in six rats.

Dose and temporal parameters in delaying injured optic nerve degeneration by low-energy laser irradiation

Low-energy laser irradiation has been reported to postpone the degenerative processes in crushed optic nerves of rats, which are part of the nonregenerable mammalian central nervous system. In the present study, we evaluated the optimal irradiation parameters for this purpose. Optic nerves of 141 rats were subjected to crush injury and then irradiated through the eye, starting at different points of time before or after the injury, for different durations and periods, using various intensities of either helium-neon laser or noncoherent infrared light (904 nm). The effect was evaluated by measurements of the compound action potentials of the nerve segments between the site of injury and the optic chiasm. The compound action potential amplitude of the crushed nonirradiated nerves, as measured 2 weeks after the injury, was found to be 0.51 +/- 0.30 mV, in contrast to 3.10 +/- 1.03 mV measured in 232 normal nerves. Irradiation with a 10.5 mW helium-neon laser for 2 and 3 min once a day for 14 consecutive days resulted in maximal preservation of action potentials (1.78 +/- 0.72 and 1.95 +/- 0.71 mV, respectively). Irradiations beginning immediately prior to the injury were as effective as irradiations beginning soon after it. Irradiations for longer than 3 min or twice a day aggravated the damage. Noncoherent infrared light was ineffective or adversely affected the injured nerves. Our experiments suggest that optimal delay of posttraumatic optic nerve degeneration in rats is attainable with 10.5 mW helium-neon laser irradiations for 2 or 3 min once a day for 14 consecutive days.

Therapeutic parameters of methylprednisolone treatment for retinal photic injury in a rat model

Methylprednisolone (MP) has been prescribed for the treatment of solar retinopathy presumably because of its anti-inflammatory effect. Recently, high doses of MP have been shown to ameliorate light-induced photoreceptor degeneration, and the mechanism of action was suggested to be the inhibition of lipid peroxidation. In this study we examined the dose-response effect and the effect of delayed treatment with MP in an established rat model of retinal photic injury. Animals received intraperitoneal injections of either MP (8, 160, or 320 mg/kg/day) or saline solution (as a control) for 2 days. Injections were started simultaneously with the commencement of light exposure or delayed for 6 or 24 h. The animals were sacrificed 6 days after light exposure, and the retinal damage was assessed by light microscopy and morphometric measurement of the outer nuclear layer (ONL) thickness. Morphologically and morphometrically, treatment with 8 mg/kg/day of MP was not effective, while treatment with 160 mg/kg/day caused better preserved photoreceptors and a thicker ONL compared with the controls (P less than 0.001). Animals administered with a dose of 320 mg/kg/day showed more severe damage to photoreceptors, resulting in a thinner ONL (P less than 0.05). When treatment with 160 mg/kg/day was delayed for 6 h, a similar efficacy as in the no-delay group was noted, but when treatment was delayed for 24 h, no beneficial effect was observed (P = 0.19). Our results demonstrated that early treatment with high doses of MP ameliorated retinal photic injury in rats.

Evaluation of the Boehringer Mannheim ES 300 immunoassay analyzer and comparison with enzyme immunoassay, fluorescence polarization immunoassay, and radioimmunoassay methods

The ES 300 (Boehringer Mannheim Diagnostics, Indianapolis, IN) is a new automated immunoassay analyzer intended for the quantitative determination of a wide range of analytes. We compared its performance to enzyme immunoassay (EIA), fluorescence polarization immunoassay (FPIA), and radioimmunoassay (RIA) methods for cortisol, digoxin, ferritin, prolactin, T4-uptake, total-T3, and TSH. The ES 300 methods showed excellent precision and the manufacturers' linearity claims were met in all cases. Cortisol, prolactin, total-T3, and TSH showed no bias and acceptable correlation with other methods. Digoxin, ferritin and total T4 showed positive bias but acceptable correlation. The ES 300 T4-uptake correlated poorly with the TDx method and showed positive bias; however, these assays appear comparable (although deficient) in diagnostic sensitivity when compared to TSH and T4 data for the same patient population. In all, we found the ES 300 to be an acceptable instrumental alternative for the high volume immunoassay laboratory.

Methylprednisolone ameliorates retinal photic injury in rats

Since lipid peroxidation induced by oxygen free radicals is believed to play an important role in retinal photic injury and high doses of certain steroids have been demonstrated to inhibit lipid peroxidation, we evaluated the effect of high-dose methylprednisolone sodium succinate on retinal injury inflicted by green light (490 to 580 nm, 160 to 180 foot-candles [1721.6 to 1936.8 lux]) for 24 hours in 36 rats. Animals received either intraperitoneal injections of the drug (80 mg/kg twice daily) or saline as a control, twice daily for 2 days, commencing with light exposure. The retinal photic injury was assessed 6 hours, 6 days, and 14 days after light exposure by light and electron microscopy, morphometric study of outer nuclear layer thickness and count of subretinal macrophages, and spectrophotometric measurement of rhodopsin. A beneficial effect of high-dose methylprednisolone was observed in retinal photic injury.

Prevalence and Properties of the Intestinal Alkaline Phosphatase Identified in Serum by Cellulose Acetate Electrophoresis

We investigated the prevalence and characteristics of intestinal alkaline phosphatase (ALP; EC 3.1.3.1) identified in human serum by cellulose acetate electrophoresis in 8% of fasting serum samples from hospital patients (n = 500) and in 35% of fasting serum samples from patients with diabetes mellitus (n = 106; not differentiated between types 1 and 2). The intestinal ALP electrophoretic band was usually heterogeneous and contained two major subtypes of ALP. Isoelectric focusing of intestinal-ALP-positive serum treated with levamisole and neuraminidase (EC 3.2.1.18) revealed two distinct regions of enzymatic activity that comigrated with ALP extracted from small intestinal and colonic mucosa. Anodic intestinal ALP was resistant to treatment with levamisole and neuraminidase and comigrated with ALP from small intestinal mucosa. The more-cathodic intestinal ALP, which comigrated with ALP from colonic mucosa, was completely inhibited by levamisole and converted by neuraminidase to a species with a more basic pI than that of neuraminidase-digested tissue-nonspecific form. This component of intestinal ALP may be of vascular origin.

Prevalence and properties of the intestinal alkaline phosphatase identified in serum by cellulose acetate electrophoresis

We investigated the prevalence and characteristics of intestinal alkaline phosphatase (ALP; EC 3.1.3.1) identified in human serum by cellulose acetate electrophoresis in 8% of fasting serum samples from hospital patients (n = 500) and in 35% of fasting serum samples from patients with diabetes mellitus (n = 106; not differentiated between types 1 and 2). The intestinal ALP electrophoretic band was usually heterogeneous and contained two major subtypes of ALP. Isoelectric focusing of intestinal-ALP-positive serum treated with levamisole and neuraminidase (EC 3.2.1.18) revealed two distinct regions of enzymatic activity that comigrated with ALP extracted from small intestinal and colonic mucosa. Anodic intestinal ALP was resistant to treatment with levamisole and neuraminidase and comigrated with ALP from small intestinal mucosa. The more-cathodic intestinal ALP, which comigrated with ALP from colonic mucosa, was completely inhibited by levamisole and converted by neuraminidase to a species with a more basic pI than that of neuraminidase-digested tissue-nonspecific form. This component of intestinal ALP may be of vascular origin.

Repair of the severely contracted socket with meshed skin graft and semi-rigid conformer

Nine severely contracted sockets were reconstructed using a meshed skin graft in conjunction with a semi-rigid conformer-stent. Particularly useful following unsuccessful surgery with mucosal grafting, or in cases where for some reason mucosal grafts cannot be obtained, this technique is superior to current procedures utilizing nonmeshed split-thickness skin grafts.

Evaluation of accommotrac biofeedback training for myopia control

A new treatment for myopia, biofeedback training for control of accommodation, has been proposed and developed over the past decade. Various reports in the literature show marked inconsistencies in the results of such treatment. A double-masked study with experimental and control groups of 15 subjects each was designed to obtain a definitive answer concerning the efficacy of this method. The parameters evaluated were visual acuity, cycloplegic and noncycloplegic retinoscopy, subjective refraction, amplitude of accommodation, and flexibility of accommodation. In all categories no significant difference was found between the control and experimental subjects. The consequences of these findings are discussed as to the benefit of treatments using this method and avenues to explore in future studies.

A nation-wide study of myopia prevalence in Israel. Findings in a population of 312,149 young adults

We conducted a nation-wide survey of the Prevalences of Myopia and other refractive errors in Israel, from data of medical examinations of an unselected population of 312,149 subjects ages 17 to 19 years. 80.47% of the population were emmetropic in both eyes. Myopia in both eyes was found in 16.27% of the population. The prevalence of monocular myopia was 1.69%. Manifest hyperopia in both eyes was found in 0.93% and astigmatism at least in one eye was found in 7.13%. The various errors of refraction (myopia, hyperopia and astigmatism) were more common among females.

Low-energy laser irradiation--a new measure for suppression of arachidonic acid metabolism in the optic nerve

Helium-neon low-energy laser (LEL) irradiation, known for its therapeutic effects in arthritis, wound healing, and muscular strain, was applied to eyes of rats that had sustained an optic nerve crush injury. Crush injury to the optic nerve resulted in a long-lasting in vitro elevation of prostaglandin E2 (PGE2) production (1.8-3.9-fold above control values during the 12 day study period). LEL irradiation per se had no effect in vitro on PGE2 production by the optic nerve; however, LEL irradiation of eyes with crushed optic nerve inhibited the enhanced production of PGE2 and leukotriene B4 in vitro by 55% and 75% during the late and immediate phase after trauma, respectively. Our findings of the suppressive effect of LEL irradiation on arachidonic acid metabolism are reminiscent of the actions of steroidal and nonsteroidal anti-inflammatory drugs, and might indicate, for the first time, the possible biochemical mechanisms associated with the clinical anti-inflammatory effects of LEL irradiation.

Comparison of the effects of argon and neodymium:YAG laser iridotomy on prostaglandin E2 and blood-aqueous barrier disruption

We compared in rabbits the effects of laser iridotomy by either argon or neodymium (Nd):YAG laser on prostaglandin E2 (PGE2) production by the iris/ciliary body, its accumulation in the aqueous humor and the aqueous protein levels. PGE2 production by the iris/ciliary body, following exposure to argon or Nd:YAG laser, was similarly enhanced, with peak levels of 22.8 +/- 4.7 and 24.1 +/- 8.2 ng/mg, respectively. An increase in aqueous PGE2 levels was more pronounced in the argon as compared with the Nd:YAG group, with peak levels of 56.7 +/- 17.3 and 20.0 +/- 7.7 ng/ml, respectively. PGE2 production correlated well with aqueous PGE2 levels in the argon group, but not in the Nd:YAG group. Protein accumulated in the aqueous humor following irradiation by both types of laser light, with higher levels occurring in the argon group. These results are indicative of possible differences in the extent of the inflammatory reaction induced by the application of argon and Nd:YAG laser light to the iris.

Video display units and visual function

The widespread use of visual display units (VDU) in the workplace has engendered visual complaints and concern for workers' health and safety. The detectable levels of radiation emitted from VDUs have been well below safety levels and exposure to VDUs does not appear to cause any organic damage to the eye. However, visual disturbance and eye discomfort affects many workers using VDUs, and these symptoms may be alleviated by a number of measures, including proper diagnosis of pre-existing ocular problems, use of special eyeglasses, and correct arrangement of lighting and furniture in the work area.

Substance abuse in pregnant women: recent experience at the Perinatal Center for Chemical Dependence of Northwestern Memorial Hospital

Drug abuse during pregnancy is associated with adverse perinatal outcome. Patterns of abuse have changed in recent years with the increasing popularity of cocaine. We compared pregnancy outcome data from 137 women receiving prenatal care in the Perinatal Center for Chemical Dependence of Northwestern Memorial Hospital with those of matched controls. Among drug-using women, the mean gestational age at delivery and mean birth weight were significantly lower than those of controls. In addition, study pregnancies were more frequently complicated by the need for antenatal hospitalization, preterm delivery, low birth weight (less than 2500 g), and abruptio placentae.

Comparison of fluorescence polarization immunoassay, enzyme immunoassay, and thin-layer chromatography for urine cannabinoid screening. Effects of analyte adsorption and vigorous mixing of specimen on detectability

Four commercial assays for the screening of cannabinoids in urine were compared. Urine specimens from 93 selected subjects were run by fluorescence polarization immunoassay on the Abbott TDx; by enzyme multiplied immunoassay with two Syva EMIT assays; and by thin-layer chromatography with the TOXI-LAB system (Marion Laboratories). The TDx cannabinoid threshold can be set anywhere from 25 to 150 micrograms per L. Twenty-five micrograms per L was chosen for this study. The thresholds for EMIT are fixed at 20 micrograms per L for one assay and 100 micrograms per L for the other. The detection limit for TOXI-LAB, according to the manufacturer, can be anywhere from 5 to 50 micrograms/L, depending on the specimen. Urines, positive by at least one method, were further analyzed by gas chromatography with mass spectrometry (GC/MS), The detection limit for the GC/MS method was 10 micrograms per L. The results showed a few false negatives and unconfirmable positives; in general, correlation was considered acceptable. Dose-response curves comparing TDx and EMIT gave paralell results, with comparable cross-reactivity for the major metabolite, 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (delta-9-THC-COOH). A dose-response study of TOXI-LAB using delta-9-THC-COOH also gave acceptable results. Adsorption to glass was investigated using spiked urine; a 27 percent reduction in concentration was caused by this phenomenon. Foaming of spiked urine caused by vigorous mixing resulted in a reversible 89 percent apparent reduction in concentration.

Dacryocystorhinostomy with silicone tubes: evaluation of 253 cases

Two hundred fifty-three patients with chronic epiphora underwent dacryocystorhinostomy combined with silicone intubation of the lacrimal drainage system. An overall success rate of 91.3% was achieved. Since the tubes were well-tolerated postoperatively, complications were rare and benign. Although our success rate is similar to those reported for similar cases using other techniques, we find that silicone intubation facilitates surgery in cases with excessive intraoperative bleeding or nasal mucosal tears, and simplifies postoperative follow-up.

Temporal parameters of low energy laser irradiation for optimal delay of post-traumatic degeneration of rat optic nerve

Compression injury of a central nerve results in its degeneration with irreversible loss of function due to the inability of the mammalian central nervous system (CNS) to regenerate. In contrast, the CNS of lower vertebrates has a high capacity to regenerate. Recently, low energy laser irradiation was shown to attenuate degeneration in injured CNS nerves. The optic nerves of rats were subjected to moderate crush, calibrated so that some electrophysiological activity was preserved. The nerves were then subjected to low energy laser irradiation (10.5 mW, 2 min daily) for various periods. The electrical activity of the nerves, distal to the site of injury, was determined by measuring the compound action potential at the termination of the experiment. Two weeks of irradiation begun immediately after injury and continued daily thereafter, resulted in a compound action potential which was significantly higher (mean +/- S.E.M. 1856 +/- 535 microV) than that of non-irradiated injured nerves (351 +/- 120 microV). The effect was temporary and subsided within a week. This two-week irradiation was slightly more effective than a treatment lasting one week (1406 +/- 225 microV) and was significantly more effective than 4 days of irradiation (960 +/- 133 microV). The number of treatments is therefore important. The time at which the treatment commences relative to the injury is also critical. Irradiation initiated two hours after the crush was about half as effective as immediate irradiation (810 +/- 42 microV). No apparent effect was evident when the laser was applied for the first time 5 h, or longer, after the crush.(ABSTRACT TRUNCATED AT 250 WORDS)

Prophylactic scleral buckling in perforating ocular injuries involving the posterior segment

Twenty patients suffering from perforating injury involving the posterior segment of the eye without retinal tear or detachment underwent posterior vitrectomy. In 12 of these where traction of the retina was suspected, prophylactic scleral buckling was performed as well. Only two of these patients developed delayed retinal detachment. Six of the eight patients who did not undergo scleral buckling at the time of the vitrectomy developed this complication. This finding was statistically significant (P = .015) and supports the use of prophylactic scleral buckling in the treatment of eyes with perforating injuries involving the posterior segment to prevent delayed retinal detachment.

Choosing an intraocular lens for patients with large pupils

Optical aberration from the positioning holes of a posterior chamber intraocular lens was encountered in three patients with wide spontaneous dilation of the pupil in scotopic conditions. One patient had a cataract extraction in his fellow eye with implantation of a posterior chamber lens without positioning holes in its optical portion and has not encountered any aberrations in that eye. We suggest that in such patients, careful preoperative measurement of the pupillary size in a dark room should be done and lenses without positioning holes on the optic should be used to prevent optical aberrations.

Intelligence, education, and myopia in males

We conducted a nationwide study of the relationship among refractive error, intelligence scores, and years of schooling in 157,748 males aged 17 to 19 years. We found a strong association of myopia with both intelligence and years of school attendance. The prevalence of myopia was found to be significantly higher in the more intelligent and more educated groups. By fitting models of logistic regressions, we worked out a formula expressing the relationship among the rate of myopia, years of schooling, and intelligence level. We found that years of schooling and intelligence weigh equally in the relationship with myopia.

A method of repair for quadriceps tendon or patellar ligament (tendon) ruptures without cast immobilization. Preliminary report

The quadriceps tendon and patellar tendon (ligament) were repaired with a Dacron vascular graft used as a tension suture material. In cases of quadriceps tendon ruptures, the Dacron graft is passed transversely through the patellar ligament just below the patella and crossed transversely at the level of the musculotendinous junction with two loops applying tension to the tendon, which brings the tendon ends together by creating a solid structure. In cases of patellar ligament ruptures, the Dacron graft is passed through a hole in the tibia posteriorly to the tibial tuberosity instead of through the patellar ligament below the patella. This technique enables early mobilization on the first day after surgery. The technique was first tested on six dogs with severed quadriceps tendons and patellar ligaments that were repaired with this suture method. All of the animals recovered from surgery and walked and ran normally on the repaired legs within 27 days and with only mild limping after 17 days. The technique was then used on six patients, four with complete quadriceps tendon rupture and two with complete tear (avulsion) of the patellar ligament (tendon). In all of the patients, excellent surgical results were obtained and leg immobilization was virtually eliminated. Physical therapy was prescribed the first day after surgery. The rehabilitation period was significantly reduced.

Role of NK cells in protection of mice against herpes simplex virus-1 infection

Natural killer (NK) cells have been implicated in the recognition and killing of a variety of virus infected target cells in vitro, yet their role in vivo remains uncertain. In these experiments, the role of NK cells in the regulation of resistance to herpes simplex virus-1 (HSV-1) was studied. Adult C57BL/6 mice are resistant to HSV-1 (HFEM strain), but are rendered highly susceptible by treatment with cyclophosphamide 24 hr prior to infection. In this model, passive transfer of 10(8) normal spleen cells or 10(7) poly I:C-treated spleen cells provided protection for 72% of the recipients. Spleen cells from NK cell-deficient beige mice similarly treated failed to engender passive protection. The phenotype of the cells responsible for transferring protection was NK1.1+, and asialo GM1+. Transfer of NK cells resulted in marked reduction of HSV titers in the livers and brains of recipients. These experiments provide direct evidence for a role for NK cells in protection against development of fatal HSV infection in mice.

Role of NK cells in protection of mice against herpes simplex virus-1 infection

Natural killer (NK) cells have been implicated in the recognition and killing of a variety of virus infected target cells in vitro, yet their role in vivo remains uncertain. In these experiments, the role of NK cells in the regulation of resistance to herpes simplex virus-1 (HSV-1) was studied. Adult C57BL/6 mice are resistant to HSV-1 (HFEM strain), but are rendered highly susceptible by treatment with cyclophosphamide 24 hr prior to infection. In this model, passive transfer of 10(8) normal spleen cells or 10(7) poly I:C-treated spleen cells provided protection for 72% of the recipients. Spleen cells from NK cell-deficient beige mice similarly treated failed to engender passive protection. The phenotype of the cells responsible for transferring protection was NK1.1+, and asialo GM1+. Transfer of NK cells resulted in marked reduction of HSV titers in the livers and brains of recipients. These experiments provide direct evidence for a role for NK cells in protection against development of fatal HSV infection in mice.

Epidemiology of retinal detachment in childhood and adolescence

The prevalence of retinal detachment during childhood and adolescence was studied in 45,000 recruits aged 17 to 19 years. History of retinal detachment was found in 13 cases (0.028%); 61.5% of these had traumatic retinal detachment, and 23.1% had high myopia without history of trauma. The age-related annual incidence of retinal detachment in patients aged ten to 19 years was calculated to be 2.9 per 100,000. The prevalence among the males was 3.7 per 10,000 and among the females 1.6 per 10,000. The difference between the sexes was not statistically significant.

A method of repair for Achilles tendon ruptures without cast immobilization. Preliminary report

A new technique for the repair of Achilles tendon ruptures has been developed with a Dacron vascular graft used as a tension suture material. The suture is passed through the calcaneal tuberosity and, with two loops applying tension to the tendon at the level of the musculotendinous junction, brings the tendon ends together by creating a solid structure. Post-operative immobilization and its possible adverse sequelae are eliminated by this procedure. The technique was first tested on five dogs with severed Achilles tendons of both hind legs. One side in each animal was repaired with this suture technique; the second leg was left as an untreated control. All the animals recovered from surgery and walked almost normally on the sutured leg within less than three weeks. The dogs did not walk on the unsutured legs. In a second procedure, the control leg was repaired by the same reparative procedure. Equally good results were obtained. The technique was then used on five patients with recent and neglected Achilles tendon ruptures or lacerations. In all instances excellent surgical results were obtained and leg immobilization was virtually eliminated. Physical therapy was begun in the immediate postoperative period. The rehabilitation period was significantly reduced.

Corneal abscesses in silicone and soft contact lens wearers

Fourteen cases of corneal abscesses in wearers of contact lenses were seen in our department during the last 3 years. The hospitalization period varied from a few days to seven weeks. In one case, it was necessary to perform penetrating keratoplasty in order to restore good vision. Cultures taken from the corneal abscesses were positive in six cases. Pseudomonas was found in five cases and Enterobacter in one case. During the three years of the survey, no hard contact lens wearers with corneal abscesses were hospitalized. Wearers of silicone contact lenses comprised 21.4% of the cases with corneal abscess. This is a high percentage considering the fact that these lenses are very rare among contact lens wearers in Israel.