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Biomedical subjects

R M Webb

Publications and source records attributed to R M Webb.

12 recordsLinked to original sources
PubMed1992

Prevalence of ompT among Escherichia coli isolates of human origin.

OmpT is a protease associated with the outer membrane of Escherichia coli and possesses a high degree of homology to the plasminogen activator, Pla, of Yersinia pestis. We show here that OmpT from intact cells can indeed activate plasminogen. Clinical specimens of E. coli were examined for protease activity and for the ompT gene. Few isolates (12%) were found to be positive for OmpT activity, whereas most (77%) carried the ompT gene and expressed the cloned protease gene. In this report we present evidence suggesting that the surface architecture of E. coli influences the activity of OmpT and that OmpT may be indicative of the pathogenic potential of the organism.

Bacterial Outer Membrane Proteins↗
PubMed1990

Spongiform encephalopathies: the physician's responsibility.

The spongiform encephalopathies encompass several diseases affecting humans and animals. In the United States, the most common of these disorders in humans is Creutzfeldt-Jakob disease. The most frequent manifestations include dementia, pyramidal tract signs, and extrapyramidal movement disorder. Several clinically distinct syndromes can be identified. Often the diagnosis is confused with other forms of dementia, and the only definitive method for establishing the diagnosis is autopsy evaluation of brain tissue. Unfortunately, since the recognition of the infectious etiology of Creutzfeldt-Jakob disease, fear has often unreasonably interfered with clinical care and autopsy evaluation of affected patients. In actuality, because of the low and restricted infectivity of the responsible agent, affected individuals present minimal risks to clinical caretakers, and handling of patient specimens is not dangerous if appropriate precautions are taken. These precautions are well established, and physicians and other health care workers should not refuse care of appropriate evaluation (including autopsy) to individuals with suspected Creutzfeldt-Jakob disease.

Aged↗
PubMed1987

The effect of estrogen on luteinizing hormone-releasing hormone binding sites in hypothalamic membranes.

The binding sites for [125I]LHRH were characterized in membranes from the hypthalamus and the effect of estrogen on the binding characteristics was studied in ovariectomized female rats. The radioligand, [125I]LHRH, was found to bind specifically to membranes from the hypothalamus at a maximal level, with an optimal temperature of 0 degrees C and a pH between 7 and 8. The binding was enhanced by NaCl at a concentration of 0.1-0.2 M. The specifically bound [125I]LHRH was only displaced by LHRH, but not by sodium iodide (NaI), bovine serum albumin and other hormones, such as thyrotropin-releasing hormone, bradykinin, oxytocin, prolactin, luteinizing hormone and growth hormone. The divalent metal ions, copper (Cu2+) and mercury (Hg2+), inhibited the specific binding of [125I]LHRH completely, whereas magnesium (Mg2+) and calcium (Ca2+) caused a decrease in binding. As revealed from Scatchard plot analysis, the binding sites for [125I]LHRH in the hypothalamus had a dissociation constant of 0.40 +/- 0.03 microM and the maximum number of binding sites was 98.55 +/- 4.34 pmol/mg protein. Treatment of female rates (ovariectomized for 3 weeks) with 4 micrograms of estradiol benzoate caused a statistically significant decrease in the maximal number of binding sites without any significant effect on the dissociation constant. However, the direct addition of estradiol hemisuccinate to the membrane preparations had no statistically significant effect on the specific binding of [125I]LHRH. The present study provides the evidence that estrogen decreases the density of binding sites for [125I]LHRH in the hypothalamus in vivo.

Animals↗
PubMed1986

Ocular Munchausen's syndrome.

Patients with contrived histories and/or self-induced physical abnormalities (Munchausen's syndrome) are often successful in deceiving physicians. We recently cared for four patients with ocular Munchausen's syndrome. Self-induced ocular manifestations included voluntary nystagmus, subconjunctival hemorrhages, chronic orbital emphysema requiring exenteration, corneal alkali burns, erosions and ulcerations, and abscesses of the periorbital area. Correct diagnoses of ocular Munchausen's syndrome were made only after extensive medical and surgical investigations. Suggestions for evaluation and treatment will also be discussed.

Adult↗
PubMed1986

A modified immunoperoxidase method for rapid diagnosis of herpes simplex I keratitis.

To study the possibility of establishing a rapid diagnosis of herpes simplex keratitis, corneas of 10 rabbits, a total of 20 eyes, were inoculated with herpes simplex virus (HSV), type I, strain PH. Epithelial keratitis developed within three days of inoculation in all the animals used. Scraping of infected corneas were smeared and examined, using a modified indirect immunoperoxidase technic. One hundred percent of the smears prepared from these corneas demonstrated positive cells. Negative findings in corneas inoculated with adenovirus 19 suggest the specificity of the reaction. To test the possibility of blockage of staining by the presumed development of circulating endogenous anti-HSV I antibodies, the corneas of eight consecutive patients who presented to the Albany Medical Center Hospital with known recurrent dendritic keratitis also were scraped and stained, using a similar procedure. Positive cells present in each of these scrapings suggest against the blocking of this immunoperoxidase method by the development of circulating anti-HSV antibodies.

Animals↗
PubMed1985

Vibrio alginolyticus conjunctivitis. First reported case.

A gravely ill patient had Vibrio alginolyticus conjunctivitis develop, possibly from contact with seashell fragments. It is believed to be the first reported instance of ocular infection by this organism. Marine Vibrio organisms must be considered as potential sources of ocular infection in patients with direct or indirect exposure to salt water habitats, or in patients who are immunocompromised.

Aged↗
PubMed1984

A new rapid immunoperoxidase diagnostic staining of herpes simplex virus 1 indolent corneal ulcer.

A tear film aspirate, from the lower fornix of a 64-year-old man with the clinical diagnosis of a herpes simplex indolent corneal ulcer, was examined via a new, rapid immunoperoxidase staining technique. This 4-hour modified immunoperoxidase stain is both sensitive and specific for herpes simplex virus type 1. The corneal epithelial cells shed in the tear film from the indolent ulcer were strongly positive for herpes simplex type 1 viral antigen using this new technique. This case report supports the theory that the pathogenesis of indolent herpetic corneal ulcers involves both a hypersensitivity response to viral antigen and an active viral infection.

Antigens, Viral↗
PubMedDate not supplied

Retinal vasculitis in ocular toxoplasmosis in nonhuman primates.

Six monkeys had prior systemic immunization followed by intraretinal challenge to each eye with Toxoplasma antigens. All eyes developed iridocyclitis, vitritis, and retinal edema, but no necrotizing retinochoroiditis. One-half of the eyes were then challenged with living organisms and the other one-half with Toxoplasma antigens. All eyes developed iridocyclitis, vitritis, and retinal edema, but no necrotizing retinochoroiditis. Four months later, the right eye of each monkey was challenged with living Toxoplasma organisms injected intraretinally. Each injected eye developed iridocyclitis, vitritis, and retinal edema 24 hours after injection, and all developed a retinal vasculitis 6 days after injection. One injected eye developed a papillitis. A subcutaneous booster of living Toxoplasma organisms in four of the monkeys failed to produce a reactivation of the iridocyclitis, vitritis, and vasculitis. These findings suggest that hyperimmunization provides protection against the development of a necrotizing toxoplasmic retinochoroiditis in nonhuman primates and that it may lead to retinal vasculitis and iridocyclitis. This study also serves as an animal model of retinal vasculitis in ocular toxoplasmosis.

Animals↗
PubMedDate not supplied

Atypical syphilitic chorioretinitis and vasculitis.

Although syphilis is frequently overlooked as a cause of ocular disease, it remains an endemic disease and its incidence is increasing. This article reports on four recent cases of ocular syphilis, including pseudoretinitis pigmentosa, chorioretinitis, and a rare presentation of an isolated retinal vasculitis involving both the arteries and the veins. Fundus photography, fluorescein angiography, and electrophysiologic testing are included. These cases show the diverse manifestations of ocular syphilis, which may involve any structure in the eye, and they demonstrate that atypical presentations are often encountered.

Adult↗
PubMedDate not supplied

Bacterial infection of a neurotrophic cornea in an immunocompromised subject.

The following is a case report of a 61-year-old woman with a 10-year history of pemphigus vulgaris, successfully treated with steroids and cytotoxic agents. The patient developed severe herpes zoster ophthalmicus, complicated by a staph-indolent corneal ulcer. This case illustrates several of the many unfortunate ophthalmological complications that may develop in the immunocompromised patient.

Corneal Ulcer↗