Biomedical subjects

D O'Day

Publications and source records attributed to D O'Day.

12 recordsLinked to original sources

PubMed1997

Endogenous autoinhibitors regulate changes in actin tyrosine phosphorylation during Dictyostelium spore germination.

Phosphorylation of proteins on tyrosine residues has been shown to govern many cellular processes, but little work has focused on the role of tyrosine phosphorylation during germination. Under optimal conditions, D. discoideum spores synchronously germinate each liberating a single amoeba. The total amount of phosphotyrosine containing proteins observed in spores was greatest during quiescence with a gradual decline during spore activation and emergence of nascent amoeba. During dormancy, tyrosine residues of actin were heavily phosphorylated, but they gradually underwent dephosphorylation upon spore activation and this process continued through emergence. Interestingly, an endogenous autoinhibitor(s), which blocks germination, induces tyrosine phosphorylation of actin. Conversely, the removal of the autoinhibitor(s) was followed by a decrease in phosphorylation. Thus, during germination of Dictyostelium spores, actin is dephosphorylated, with the level of phosphorylation regulated by the autoinhibitor(s) and/or the autoactivator. This change in actin phosphorylation appears to play a direct role since actin dephosphorylation and reorganization is a necessary prelude to germination.

Actins↗

PubMed1994

Detection of herpes simplex viral DNA in the iridocorneal endothelial syndrome.

OBJECTIVE: To test the hypothesis that the iridocorneal endothelial (ICE) syndrome has a viral origin by comparing the incidence of viral DNA in corneal specimens from patients with the ICE syndrome and from controls. DESIGN: Thirty-one corneas obtained from 25 patients with the ICE syndrome and six with chronic herpetic keratitis (n = 31) were compared with 30 control specimens obtained from 15 healthy donors and from 15 patients with other, nonviral chronic corneal diseases. METHODS: Primer pairs and polymerase chain reaction methods were used to identify and amplify either a segment of the DNA polymerase gene in the case of the herpes simplex and zoster viruses or a region of the nuclear antigen gene for the Epstein-Barr virus. The oligonucleotide amplified by polymerase chain reaction was fully characterized with the use of restriction enzyme, hybridization, and sequence analyses to determine that it contained the expected base pair sequence. RESULTS: Sixteen of 25 ICE syndrome specimens and four of six herpetic keratitis specimens were positive for herpes simplex virus (HSV) DNA. All nine ICE syndrome specimens tested were negative for the presence of DNA from the herpes zoster or the Epstein-Barr viruses. Controls were uniformly negative for HSV DNA whether they were obtained from ostensibly normal corneas (n = 15) or from corneas with intestinal keratitis, aphakic bullous keratopathy, or keratoconus (n = 15). Tissue samples cut from positive ICE syndrome specimens yielded negative results when retested after the endothelial layer was removed. These findings indicate that localization of HSV DNA is within the endothelium, the tissue primarily involved in the pathogenesis of the ICE syndrome. CONCLUSIONS: Polymerase chain reaction evidence shows that HSV DNA is present in a substantial percentage of ICE syndrome corneal specimens and that HSV-DNA is absent in normal corneas and in corneas from patients with three other chronic corneal diseases. These results provide direct evidence to support our hypothesis that the ICE syndrome has a viral origin. We discussed clinical implications, including possible therapeutic interventions.

Base Sequence↗

PubMed1993

The content and cost of cataract surgery.

Although more than 1 million cataract surgeries are performed annually in the United States, little is known about the frequency of use or cost of various services provided in connection with this procedure. To assess the frequency with which various ophthalmic, optometric, anesthesia, and medical services are provided in conjunction with cataract surgery and to estimate the cost to Medicare associated with those services, we analyzed 1985 through 1988 Medicare claims records of a nationally representative 5% sample of Medicare beneficiaries. The experience of 57,103 Medicare beneficiaries who underwent extracapsular cataract surgery in 1986 or 1987 that was not combined with another ophthalmologic procedure formed the basis of our analysis. Projections for current costs were performed using 1991 charges allowed by Medicare for physician services. We estimate that the median charge allowed by Medicare for a "typical" episode of cataract surgery in 1991 was approximately $2500. In addition to the $3.4 billion that Medicare spent in 1991 on such "typical" episodes, Medicare spent more than $39 million on miscellaneous "atypical" preoperative ophthalmologic tests, such as specular microscopy (14% of cases) and potential acuity testing (8% of cases), more than $7 million on postoperative ophthalmologic diagnostic tests, such as fluorescein angiography (3% of cases), and more than $18 million on perioperative medical services (most commonly electrocardiography and chest roentgenography). The major determinants of the cost to Medicare associated with cataract surgery are the rate of performance of cataract surgery and neodymium-YAG laser capsulotomy and the charges allowed for these procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Cataract Extraction↗

PubMed1986

Outbreak of Candida parapsilosis endophthalmitis after cataract extraction and intraocular lens implantation.

Between November 1983 and January 1984, 13 cases of Candida parapsilosis endophthalmitis occurred in Florida, Georgia, and Tennessee in patients who had had an intraocular lens implantation (IOLI) or cataract extraction with an IOLI. This outbreak followed the introduction in July 1983 of a new brand of balanced salt solution (BSS) used as an intraoperative ophthalmic irrigation solution. This product was subsequently recalled because of intrinsic fungal contamination. A retrospective cohort study including 704 ophthalmology patients at risk for exposure to this brand of BSS revealed that definite exposure to that product was a significant risk factor for C. parapsilosis endophthalmitis (P less than 0.001, Fisher exact test). A retrospective case control study including 203 control patients with definite exposure to BSS suggested that exposure to systemic steroids (P = 0.007, Fisher exact test) was an additional risk factor for C. parapsilosis endophthalmitis. Treatment modalities among the 13 patients included topical, intraocular, or systemic antifungal therapy (or a combination of these modalities) in 13 patients and vitrectomy in 10 patients. No patients had systemic symptoms or complete visual loss. Laboratory investigations showed a 6.7% overall contamination of the product with C. parapsilosis. After recall of the product by the manufacturer, no patients having a cataract extraction or IOLI at the institutions studied are known to have developed C. parapsilosis endophthalmitis.

Candida↗

PubMed1982

Sexual differentiation of arachidonate toxicity in mice.

Mature male and female mice 50 days of age were challenged with i.v. sodium arachidonate at doses of 12.5, 25, 50 and 100 mg/kg. A dose-dependent response in terms of mortality was observed. Males were significantly more susceptible to arachidonate-induced mortality than females at the 25 and 50 mg/kg doses (P less than .05). The 100 mg/kg dose produced 100% mortality in both sexes. When mice aged 23, 29, 35 and 50 days were challenged with 50 mg/kg of arachidonate, no gender difference was observed until mice were 35 days of age, at which time the male mortality was 80%, compared to 57% for female mice (P less than .05). Mice gonadectomized at 23 days and intact mice 23 days of age were treated with s.c. estradiol, testosterone or vehicle for 7 days before arachidonate challenge. Among these groups, the gonadectomized females and intact males were significantly protected by estradiol when compared to the appropriate controls (P less than .05). In contrast, testosterone pretreatment had no significant effect on mortality. These results demonstrate that the development of the gender difference in arachidonate-induced mortality in mice is dependent upon the presence of gonadal hormones in the immature stages.

Adrenal Glands↗

PubMed1978

Clinical implications of preseptal (periorbital) cellulitis in childhood.

The available hospital records of all pediatric patients diagnosed as having periorbital, preseptal or orbital cellulitis over a five-year period were reviewed and compared to previously reported series. Only two of 39 patients had orbital cellulitis. The 37 patients with preseptal cellulitis had two characteristic clinical presentations. Twenty-two children had local trauma, abscesses, insect bites, or impetigo as the inciting event for their cellulitis. Infection was usually caused by staphylococci or streptococci. In contrast, 15 children, 12 of whom were under 36 months, had associated upper respiratory tract infections and otitis. Haemophilus influenzae was the most commonly implicated pathogen and the children were at risk of bacteremia and metastastic infection. Determination of the location of the infection in the orbit and consideration of the clinical presentation of the patient with infection in and about the orbit are of assistance in choosing appropriate therapy. Young children who have upper respiratory tract symptoms in association with preseptal cellulitis should receive antibiotic coverage for Haemophilus.

Abscess↗

PubMed1975