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Biomedical subjects

J L Marx

Publications and source records attributed to J L Marx.

At least 19 recordsLinked to original sources
PubMed2000

Degeneration of cone photoreceptors induced by expression of the Mas1 protooncogene.

Although transgenic expression of oncogenes typically leads to tumorigenesis, oncogene expression directed to the rod photoreceptors leads to cell death without tumor formation. To evaluate the cellular and functional changes induced in cone photoreceptors by an oncogene, the Mas1 protooncogene was targeted to the cones of transgenic mice by the human red/green opsin promoter. Mas1 was chosen because of its exclusive expression in the nervous system and its homology to opsin. The overall histologic appearance of the transgenic retina was normal and retinal tumors were never observed. While rod-mediated electroretinograms were normal in all respects, cone-mediated responses were diminished in direct relationship to the level of transgene expression as determined by Northern blot analysis. Responses of UV- and green-sensitive cones were reduced equivalently, and Northern analysis and immunocytochemistry indicated that cone photoreceptor densities were markedly diminished throughout transgenic retinas. These results indicate that oncogene expression in cones induces cell death without tumor formation and support the possibility that aberrant oncogene expression may underlie some forms of hereditary retinal diseases. The Mas1 transgenic mice may be useful in understanding the cone photoreceptor degeneration that occurs in cone dystrophies and age-related macular degeneration and in evaluating potential therapies for these disorders.

Aging↗
PubMed1999

Ocular injuries from paintball pellets.

OBJECTIVE: To evaluate the ocular effects of blunt trauma due to injury from a paintball pellet. DESIGN: Noncomparative case series. PARTICIPANTS: Thirteen patients who suffered ocular injury from paintballs are described. The patients presented to six different civilian and military emergency departments in tertiary care medical centers. INTERVENTION: Patients were treated for the ocular injury. MAIN OUTCOME MEASURES: Patients were evaluated for initial and final visual acuity. The reason for persistent loss of vision was delineated. RESULTS: There were 12 males and 1 female with an average age of 21 years (range, 12-33 years). Eleven of the 13 had no ocular protection at the time of the ocular injury. On initial examination, nine patients had a hyphema, nine had a vitreous hemorrhage, six had a retinal tear or detachment, three had corneal or corneal-scleral ruptures, and one had traumatic optic neuropathy. The final visual acuity was 20/40 or better in two patients, 20/50 to 20/150 in three patients, and 20/200 or worse in eight patients. CONCLUSION: Injuries due to paintball pellets can result in severe ocular damage and significant loss of vision. Eyecare professionals should be aware of the risks of this sport and must strongly advise participants to wear adequate protection when involved in this activity.

Adolescent↗
PubMed1998

Retinopathy of prematurity: evaluation of risk factors.

OBJECTIVES: The purpose of this study was to determine what risk factors play a role in the development of retinopathy of prematurity (ROP). STUDY DESIGN: Data were collected on 157 infants born and cared for in one institution between January 1991 and July 1994. Initially we evaluated all children enrolled in the study to determine potential risk factors for the development of ROP. We subsequently compared multiple variables for ROP positive singletons with ROP positive twins to determine ROP risk factors for each group and to determine if one group was more susceptible to a given risk factor. RESULTS: Of the 157 infants examined, 72 infants (46%) developed ROP. Infants who developed ROP had a lower gestational age, a lower birth weight, a higher number of days on oxygen/ventilator, more days in the intensive care unit (ICU), a greater need for steroids and a higher incidence of sepsis when compared to infants who did not develop ROP. There was no significant difference noted between singleton and twin gestation infants that developed ROP when comparing gestational age, weight, ventilator time or length of ICU stay. Total number of days on oxygen therapy was higher in the singleton group and this difference did reach statistical significance. CONCLUSIONS: Several risk factors are associated with a higher incidence of ROP. These variables may not be independent risk factors but may be a sign of the increased severity of illness associated with those infants who are born earlier with a lower birth weight. Multiple gestational births do not appear to increase the risk of developing ROP when compared to a similar group of singleton birth infants.

Female↗
PubMed1996

Use of the ganciclovir implant in the treatment of recurrent cytomegalovirus retinitis.

OBJECTIVE: To evaluate the efficacy of the ganciclovir implant in the treatment of recurrent cytomegalovirus (CMV) retinitis. METHODS: Patients with acquired immunodeficiency syndrome and recurrent CMV retinitis were evaluated for entry into the study. A ganciclovir implant was inserted in 91 eyes of 70 patients between October 1992 and October 1995. The efficacy of the implant and visual results were retrospectively reviewed. RESULTS: Fifty-three (76%) of 70 eyes had inactive CMV retinitis 1 month postoperatively (positive initial response). Twenty-one eyes of 19 patients had less than 1 month of follow-up. Nineteen (36%) of 53 eyes developed recurrent CMV retinitis. The median time to recurrence for those patients with a positive initial response was 7 months. Forty-eight (84%) of 57 patients with follow-up longer than 1 month after implant insertion in the first eye received systemic anti-CMV medication during the study. The cumulative risk for developing a retinal detachment was 23% at 6 months following implant insertion. Other complications included vitreous hemorrhage, hyphema, and suprachoroidal implantation of the device. CONCLUSION: The ganciclovir implant is effective as an adjunct to continued systemic therapy in those patients with recurrent CMV retinitis.

AIDS-Related Opportunistic Infections↗
PubMed1996

Cytomegalovirus papillitis in patients with acquired immune deficiency syndrome. Visual prognosis of patients treated with ganciclovir and/or foscarnet.

BACKGROUND: Of those patients with acquired immune deficiency syndrome in whom cytomegaloviral retinitis develops, cytomegaloviral papillitis reportedly develops in up to 4% as well. Although occasionally patients have a good visual outcome, the majority have a poor visual prognosis, with a visual acuity of 20/200 or worse, even with treatment. METHODS: To evaluate the effects of prolonged induction with foscarnet or ganciclovir on the visual prognosis of cytomegalovirus (CMV) papillitis, the records of 22 patients seen between 1990 and 1995 at the Los Angeles County-University of Southern California Eye Clinic were reviewed. Papillitis was defined as greater than 270 degrees of disc edema/blurring of the disc margins as seen on direct examination and on color fundus photographs. RESULTS: Eighteen patients with a mean initial visual acuity of 20/69 (range, 20/ 15-20/400) were treated with induction doses of intravenous ganciclovir (range, 5-7.5 mg/kg twice daily) or foscarnet (range, 60-90 mg/kg twice or 3 times daily) for a mean of 3.3 weeks. The mean follow-up period was 4.8 months (range, 1-13 months). These patients maintained a mean final visual acuity of 20/68 (range, 20/ 25-20/400) with greater than 90% resolution of the papillitis. The remaining four patients had poor outcomes (visual acuity < 20/400) because of progressive CMV papillitis or retinitis. The median survival time was 4.5 months from the diagnosis of papillitis, but 7 months from the onset of CMV ocular infection. CONCLUSION: Patients with CMV papillitis have good visual prognosis when managed with high and prolonged doses of intravenous foscarnet and/or ganciclovir.

AIDS-Related Opportunistic Infections↗
PubMed1996

The effects of California Proposition 187 on ophthalmology clinic utilization at an inner-city urban hospital.

PURPOSE: To determine the effect on ophthalmology clinic utilization at a major public inner-city hospital of California Proposition 187 and the debate surrounding its passage. Proposition 187 was a statewide referendum passed by 63% of the electorate in the November 1994 election that would restrict social services to undocumented immigrants and require providers to report them to immigration authorities. METHODS: The ophthalmology clinic volume at the Los Angeles County/ University of Southern California Medical Center was analyzed from October 1 to December 31, 1993 and 1994. RESULTS: New walk-in patients significantly decreased (P < 0.001) for a 2-month period around the election, but returned to baseline levels in December 1994. The new patient cancellation and no show rate was not affected. No change in return patient behavior was noted for general and specialty clinics. CONCLUSIONS: Proposition 187 may have caused a statistically significant decrease in new walk-ins to the ophthalmology clinics during a 2-month period surround the November 1994 election, but it had no measurable effect on other indicators of utilization. In addition, utilization rates returned to baseline after the implementation of Proposition 187 was stayed by the judicial system, and concern that providers would be required to report undocumented immigrants to authorities was alleviated.

Appointments and Schedules↗
PubMed1992

Rapid plasmid DNA isolation from mucoid gram-negative bacteria.

Exopolysaccharides interfere with the isolation and characterization of plasmid DNA from gram-negative bacteria. To repress capsular polysaccharide production, bacteria were cultured in medium containing bismuth nitrate and sodium salicylate. Rapid removal of other contaminating bacterial surface components was achieved by mild acidic zwitterionic detergent extraction. After treatment, bacterial cells were more readily lysed in alkaline detergents. The resulting plasmid preparations contained virtually no capsular polysaccharide and relatively small quantities of lipopolysaccharide and protein, yet they produced yields of nucleic acids similar to those of conventional plasmid preparations. Conventional preparations from encapsulated organisms were largely insoluble and appeared as smears following agarose gel electrophoresis, with indefinite plasmid banding. Plasmids prepared by the new method were highly soluble in conventional buffers and exhibited high-resolution plasmid banding patterns in agarose gels. Plasmids as large as 180 kbp could be isolated and visualized, without apparent nicking, and were readily digested by restriction endonuclease enzymes. The method proved effective with encapsulated or mucoid strains of Klebsiella pneumoniae, Escherichia coli, Acinetobacter anitratus, Salmonella typhimurium, and Enterobacter species. The complete method for plasmid isolation was not suitable for Pseudomonas aeruginosa because of the inhibitory effects of bismuth. Thus, removal of contaminating bacterial surface structures enabled the rapid isolation and characterization of plasmids from mucoid clinical isolates, without the use of organic solvents, CsCl gradients, or expensive, disposable columns.

Bacterial Typing Techniques↗
PubMed1992

Bilateral dacryocystitis after punctal occlusion with thermal cautery.

A 61-year-old woman developed acute bilateral dacryocystitis secondary to Staphylococcus aureus 3 weeks after undergoing punctal occlusion with thermal cautery for keratoconjunctivitis sicca. The dacryocystitis resolved with intravenous antibiotics, aspiration of the lacrimal sacs, injection of sulfacetamide into the lacrimal sacs, and bilateral dacryocystorhinostomy. Preexisting bilateral nasolacrimal duct obstruction was postulated as the underlying cause. In these cases, irrigation of the lacrimal system is recommended before proceeding with punctal occlusion.

Anti-Bacterial Agents↗