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Biomedical subjects

S M Meyers

Publications and source records attributed to S M Meyers.

At least 19 recordsLinked to original sources
PubMed1996

Coagulase-negative Staphylococcus endophthalmitis after cataract surgery with intraocular vancomycin.

PURPOSE: We studied a case of postoperative coagulase-negative Staphylococcus endophthalmitis in a 79-year-old man who had undergone cataract extraction in which vancomycin had been used intraoperatively in the infusion fluid. METHODS: The medical records were reviewed for the clinical history, ocular findings, and the vitreous and anterior chamber culture results. RESULTS: Acute, postoperative coagulase-negative Staphylococcus endophthalmitis developed in the patient in whom vancomycin had been used intraoperatively in the infusion fluid. CONCLUSIONS: Restraint is urged in the prophylactic use of vancomycin in the infusion fluids.

Acute Disease↗
PubMed1996

Bacterial contamination of anaerobic vitreous cultures: using techniques employed for endophthalmitis.

PURPOSE: To investigate the occurrence of contaminated cultures of vitreous specimens from non-infected eyes obtained using anaerobic techniques employed for endophthalmitis. METHODS: Vitreous specimens were obtained using meticulous sterile techniques employed for endophthalmitis from seventeen patients undergoing pars plana vitrectomy for non-infective indications: vitreous hemorrhage (12 eyes), retinal detachment (3), Coat's disease (1), and congenital dislocated lens(1). Vitreous specimens were inoculated in the operating room onto an anaerobic blood agar plate and into thioglycolate broth. Bacterial growth occurring before 10 days was considered positive. RESULTS: Three organisms were isolated from three separate eyes. One colony of Staphylococcus species was isolated on an anaerobic blood agar plate on day 3. A single colony of Propionibacterium acnes grew on an anaerobic blood agar plate on day 6. Alpha-hemolytic streptococci grew from thioglycolate broth on day 10. CONCLUSIONS: Growth as detected in this study might represent contaminating rather than an infecting organism in an eye suspected of having endophthalmitis.

Adult↗
PubMed1995

Retinal changes associated with neurofibromatosis 2.

INTRODUCTION: Neurofibromatosis (NF) is now known to be more than one disease. NF2, formerly classified as central neurofibromatosis, is characterized by bilateral vestibular schwannomas, previously termed "acoustic neuromas", and is much less common than NF1. Lens opacities at an early age have been described in approximately 85% of NF2 patients. PURPOSE: To determine the frequency of retinal abnormalities in NF2 patients. METHODS: We prospectively examined 15 consecutive patients who met the diagnostic criteria of NF2. RESULTS: We observed an epiretinal membrane in the macular or paramacular area in 12 of 15 patients, and a combined pigment epithelial and retinal hamartoma in the macula of one patient who also had an epiretinal membrane in the macula of the other eye. Additionally, 11 patients had central posterior cortical, subcapsular, or peripheral cortical lens opacities. CONCLUSIONS: Children or young patients with epiretinal membranes, combined pigment epithelial retinal hamartoma, and lens opacities that are not the result of other ocular disorders should have a neurologic evaluation and a careful family history for NF2.

Adolescent↗
PubMed1995

A twin study of age-related macular degeneration.

PURPOSE: To determine the importance of genetic factors in age-related macular degeneration by using a twin study to compare the concordance of age-related macular degeneration in monozygotic and dizygotic twin pairs. METHODS: We prospectively examined 134 consecutive twin pairs and two triplet sets for age-related macular degeneration. The zygosity was determined by genetic laboratory tests. RESULTS: The concordance of age-related macular degeneration was 100% (25 of 25) in monozygotic and 42% (five of 12) in dizygotic twin pairs. The other twins or triplets had no macular changes of age-related macular degeneration. CONCLUSIONS: The statistically significant higher concordance of age-related macular degeneration in monozygotic than in dizygotic twin pairs and the clinical heterogeneity of age-related macular degeneration strongly suggest the importance of genetic and nongenetic factors, respectively, in age-related macular degeneration.

Adult↗
PubMed1994

Lens-induced glaucoma 65 years after congenital cataract surgery.

PURPOSE/METHODS: We observed an unusual case of lens-induced glaucoma that occurred 65 years after congenital cataract extraction. We successfully treated the patient by removing the residual lens material with pars plana vitrectomy. RESULTS/CONCLUSIONS: The intraocular specimen exhibited lens material, epithelial cells, and macrophages. It may have taken years for the residual lens material to denature and break into small pieces, which resulted in phacolytic and lens-particle glaucoma.

Aged↗
PubMed1994

Comparative toxicity of azinphos-methyl to house mice, laboratory mice, deer mice, and gray-tailed voles.

A laboratory toxicity study on house mice and laboratory mice (Mus musculus), gray-tailed voles (Microtus canicaudus), and deer mice (Peromyscus maniculatus) was conducted as part of a comprehensive laboratory and field study to field validate laboratory-based risk assessment of pesticides. The single dose oral LD50 for the organophosphorus insecticide azinphos-methyl (Guthion) was 10, 11, 32, and 48 mg/kg body weight in wild house mice, laboratory mice, gray-tailed voles, and deer mice, respectively. Ten-day dietary LC50s were 277 ppm for laboratory mice, 297 ppm for gray-tailed voles, and 1,180 ppm for deer mice. All treated animals lost more weight, consumed less food, and had depressed brain cholinesterase (ChE) activity compared to controls. Five-day LC50s were significantly higher than 10-day LC50s for laboratory mice and deer mice. For all three species, animals that died during dietary LC50 tests had mean ChE activity of 50-55% while survivors had 56-70% of controls. The conclusions were that: (1) Laboratory mice were not representative of deer mice or gray-tailed voles with respect to sensitivity to azinphos-methyl, but provided a conservative estimate for risk assessment; (2) 10-day dietary LC50 tests indicate substantially greater estimates of toxicity of azinphos-methyl to rodents than do 5-day tests; and (3) brain ChE depression of 45-50% was lethal in these species.

Animals↗
PubMed1994

A twin study on age-related macular degeneration.

A prospective twin study on age-related macular degeneration (AMD) recruited 83 monozygotic pairs, 28 dizygotic pairs, and one triplet set from 1986 through 1993. Zygosity was determined by genetic testing of red cell markers, HLA antigens, or specific DNA loci. There were no twin pairs in which I collected data on only one twin. To decrease ascertainment bias, after 1991 the recruitment notice did not mention AMD, and I did not ask about a history of eye disease before the eye examination. Because of this, twin pairs recruited from 1986 through 1991 were statistically analyzed separately from those after January 1, 1992. From 1986 through 1991, 23 twin pairs were recruited; 11 monozygotic and 2 dizygotic pairs had nonAMD retinal changes or no retinal abnormalities, 9 monozygotic pairs with AMD were all concordant, and 1 dizygotic pair was discordant for basal laminar drusen. The concordance rate of AMD did not differ significantly between monozygotic and dizygotic twin pairs (P = .10) for 1986 through 1991. In 1992 and 1993, 88 twin pairs and one triplet set were recruited; 49 monozygotic and 19 dizygotic pairs had nonAMD retinal changes or no retinal abnormalities, 14 monozygotic pairs with AMD were all concordant, and 2 of 7 dizygotic pairs were concordant for AMD. The nonidentical triplets (1 with and 2 without AMD) were categorized as one of the discordant dizygotic pairs in the statistical evaluation. In nontwin age-matched (within 2 or 5 years of age) or age- and sex-matched sibling pairs the concordance rate of AMD ranged from 16% to 25%. The concordance rate of AMD was significantly higher in monozygotic than in dizygotic twins (P = .001) for 1992 and 1993. The concordance rate was higher for monozygotic twin pairs recruited in 1992 and 1993 than in any of the four subsets of nontwin age-method or age- and sex-matched sibling pairs (P < .0001). Overall, from 1986 through 1993, 23 of 23 monozygotic and 2 of 8 dizygotic twin pairs were concordant for AMD; this included the one dizygotic pair which was discordant for basal laminar drusen. The data of this study strongly suggest a genetic predisposition to AMD.

Adult↗
PubMed1993

Chronic radiation-induced alteration in hematopoietic repair during preclinical phases of aplastic anemia and myeloproliferative disease: assessing unscheduled DNA synthesis responses.

Protracted, low-daily-dose gamma-ray exposure (3.8-7.5 cGy/day) segregates canines into separate survival- and pathology-based subgroups by the early elicitation of distinct, repair-mediated hemopathological response pathways. In this study, we verified the blood and marrow responses of two major subgroups prone to either aplastic anemia or myeloproliferative disease, along with two variants, and extended our analyses of hematopoietic repair to include studies of DNA repair in bone marrow blasts using an autoradiographically based unscheduled DNA synthesis (UDS) assay. The myeloproliferative disease-prone subgroup exhibited extended survival (> 200 days), related to partial, gradual restoration of blood leukocyte, platelet, and marrow progenitor levels following an initial phase of acute suppression. Marrow blasts taken during the restoration phase showed expanded and qualitatively modified UDS relative to marrow blasts of age-matched control animals. The amount of UDS per blast (signal strength) increased significantly, as did the number of UDS-positive cells and their sensitivities to high-dose UV induction and 1-beta-D-arabinofuranosylcytosine chemical inhibition. A nonevolving myeloproliferative disease-prone variant having prolonged survival (> 200 days) and restored blood cells and marrow progenitor levels also had marrow blasts with expanded UDS responses, but these were uniquely evoked by low (but not high) doses of UV inducer. The aplastic anemia-prone subgroup was characterized by short survival (< 200 days), progressive decline (without restoration) in all measured blood and marrow compartments, and largely nonsignificant changes in UDS responses of marrow blasts. A variant of this aplastic anemia-prone subgroup (with comparable short survival due to markedly ineffective hematopoiesis, but expressing select preleukemic features) exhibited reduced numbers (relative to age-matched controls) of highly responsive, UDS-positive marrow blasts (in terms of UDS signal strength and increased to sensitivity 1-beta-D-arabinofuranosylcytosine-induced UDS inhibition). From these observations we conclude that: (a) the UDS response of marrow blasts, a correlate of hematopoietic progenitorial repair, is altered differentially within selected subgroups of animals under chronic radiation exposure; and (b) the nature of altered UDS repair response patterns appears to be largely related to the preclinical status/predisposition of the individual animal and thus may provide prognostically useful information in the clinical monitoring of chronically irradiated individuals with minimal but evolving hematological disease.

Anemia, Aplastic↗
PubMed1993

Combined extracapsular cataract extraction, posterior chamber intraocular lens implantation, and pars plana vitrectomy.

The surgical management of coexisting cataract and vitreoretinal disease has been controversial, particularly for eyes with a history of proliferative diabetic retinopathy (PDR) or chronic uveitis. We retrospectively studied the results of combined extracapsular cataract extraction (ECCE), posterior chamber intraocular lens (PC-IOL) implantation, and pars plana vitrectomy in 20 eyes of 16 patients. The indications for combined vitrectomy included dense, nonclearing vitreous hemorrhage attributed to PDR in 10 eyes, age-related macular degeneration in 2, and trauma in 1. The remaining 7 eyes had pars plana vitrectomy to remove inflammatory vitreous cell and debris associated with chronic uveitis. Follow up ranged from 4 to 32 months (average, 17.4 months). Visual acuity improved in 19 eyes (95%)--to 20/100 or better in 12 (60%). The improvement ranged from 1 to 13 Snellen lines (average, 4.9 lines). Postoperative visual acuity improvement averaged 7.5 Snellen lines for eyes with chronic uveitis, 7.0 lines for those with age-related macular degeneration, and 3.3 lines for those with a history of PDR. Postoperative visual acuity was less than 20/100 in 8 eyes (40%). In most cases, these latter results were attributed to macular changes associated with the underlying ocular disease. Our results confirm previous studies that have shown that combined ECCE/PC-IOL implantation and pars plana vitrectomy is a well-tolerated surgical procedure for diabetics, which can provide clear anterior and posterior segment media. In addition, our results suggest that this combined procedure can be useful in restoring vision in certain eyes with uveitis in the short-term postoperative period.

Adult↗
PubMed1992

Ocular findings associated with neurofibromatosis type II.

BACKGROUND: Neurofibromatosis has been recently acknowledged as consisting of a number of different diseases. Neurofibromatosis (NF) type I and NF type II are the most clearly defined. Type II is characterized by bilateral acoustic neuromas and is rare (its incidence is 1/50,000). The previously reported ocular associations of NF type II are posterior subcapsular cataracts, Lisch nodules, and combined hamartomata of the retinal pigment epithelium and retina. In this study, the authors attempt to define further the ocular manifestations of NF type II. METHODS: The authors prospectively examined 9 patients who met the diagnostic criteria for NF type II (age, 18 to 38 years; mean, 25 years). RESULTS: Seven of nine patients had epiretinal membranes in the posterior pole. None of these epiretinal membranes were visually significant. In addition, five patients had central posterior cortical cataracts and five had peripheral wedge-shaped cortical cataracts. CONCLUSION: The presence of epiretinal membranes in young patients may represent another clinical finding associated with NF type II. Epiretinal membranes, central posterior cataracts, peripheral cortical cataracts, or combined hamartoma of the retinal epithelium and retina in young patients should alert the ophthalmologist to include NF type II in the differential diagnosis in patients with stigmata of NF type II.

Adolescent↗
PubMed1992

Variation of perfluoropropane disappearance after vitrectomy.

In complex cases of retinal detachment, perfluoropropane (C3F8) is frequently used after vitrectomy for tamponade of retinal breaks. Results of previous studies of C3F8 disappearance using 10% C3F8 after vitrectomy in human eyes have differed significantly. A wide variation in the decay rate and half life of C3F8 after vitrectomy was observed in eyes that had similar clinical settings and received the same C3F8 concentration (15%, 20%, or 25%). This occurred even in those eyes where there was no change in the geometric contour of the eye after a repeat vitrectomy.

Eye↗
PubMed1992

Comparative response of nestling European starlings and red-winged blackbirds to an oral administration of either dimethoate or chlorpyrifos.

Red-winged blackbird (Agelaius phoeniceus; blackbird) and European starling (Sturnus vulgaris; starling) nestlings were dosed with either 2.0 mg/kg body mass chlorpyrifos, 50.0 mg/kg body mass dimethoate, or a propylene glycol carrier in situ. Four growth measurements (body mass, culmen, tarsus, wing) were recorded from nestlings to determine if these organophosphorus compounds caused perturbations in development at sublethal concentrations. Blackbird nestlings were more sensitive to chlorpyrifos than starling nestlings were more sensitive to dimethoate than blackbird nestlings. This was in contrast to reported adult LD50 values where the reverse was true. Blackbird nestlings were more tolerant of a substantially higher concentration of dimethoate than the adult LD50. The sensitivity of starling nestlings to dimethoate was similar to adults. In contrast, juveniles of both species were more sensitive to chlorpyrifos than adults. After the initial 24 hr, surviving nestlings dosed with either chemical recovered and continued their development. Exposure to dimethoate caused significant depression in starling body mass during the initial 24 hr period. Survivors obtain body mass equal to controls within 48 hr post dosing. The research presented here demonstrates that the simple supposition that passerine nestlings are typically more sensitive to toxins than adults does not always hold true. It also indicates that sensitivity relationships among adults do not necessarily apply to their nestlings.

Administration, Oral↗
PubMed1991

Acute multifocal inner retinitis.

Two patients developed acute changes in vision two to four weeks after a febrile illness. On ophthalmic examination, each patient had bilateral vitreitis without anterior segment inflammation and multiple, bilateral, round, yellow-white inner retinal lesions that were located in the posterior pole and midperiphery. Laboratory tests did not contribute to a diagnosis. Symptomatic visual loss was caused by neuroretinitis and serous retinal detachment in one patient and by an occluded branch retinal artery in the other. The multifocal retinal lesions resolved gradually without treatment over several months with minimal or no residual retinal changes. Acute multifocal inner retinal lesions may be associated with a preceding nonspecific viral illness and may cause a sudden change in vision if associated with neuroretinitis, serous retinal detachment, or retinal vessel occlusion. We have termed this constellation of ophthalmic findings acute multifocal inner retinitis.

Acute Disease↗
PubMed1991

Management of intraretinal metallic foreign bodies without retinopexy in the absence of retinal detachment.

In the management of intraocular metallic foreign bodies impacting or embedded in the posterior retina but without retinal detachment, retinopexy can be difficult or dangerous because of surrounding retinal, subretinal, or choroidal hemorrhage, or the proximity of the foreign body to the optic disc and macula. The authors prospectively managed five such cases by pars plana vitrectomy and foreign body removal without intraoperative or postoperative retinopexy. Fluid gas exchange was performed in only one case. No attempt was made to create a posterior vitreous detachment in any of the cases. After follow-up, ranging between 8 and 35 months, all cases had attached retinas and chorioretinal adhesion around the foreign body site. None of the cases had preretinal macular fibrosis. Four of the five cases had a best corrected visual acuity of 20/20 or better. The other, an aphakic 3-year-old patient, was amblyopic. Spontaneous chorioretinal adhesion appears to obviate the need for retinopexy in these selected cases. The avoidance of retinopexy and fluid gas exchange may decrease the risk of retinal detachment and preretinal macular fibrosis.

Adolescent↗
PubMed1991

Retinal detachment as a complication of retrobulbar anesthesia.

The authors report an unusual case of retinal detachment after cataract surgery in a 48-year-old man in which it appeared that the retrobulbar needle passed through the sclera and tracked beneath the retina before perforating the retina superior to the disc. The cause of the detachment was not clearly defined until a depigmented line was observed after reattachment of the retina.

Anesthesia, Local↗