The pathogenesis of keratoconus.

Keratoconus (KC) is a common degenerative condition that frequently results in visual loss with an onset typically in early adulthood. It is the single most common reason for keratoplasty in the developed world. The cause and underlying pathological mechanism are unknown, but both environmental and genetic factors are thought to contribute to the development of the disease. Various strategies have been employed to address the gap in our understanding of this complex disease, with the expectation that over time more sophisticated therapies will be developed. In this review we summarise our current knowledge of the aetiology and risk factors associated with KC.

ADVIRC is caused by distinct mutations in BEST1 that alter pre-mRNA splicing.

Autosomal dominant vitreoretinochoroidopathy (ADVIRC), a retinal dystrophy often associated with glaucoma and cataract, forms part of a phenotypic spectrum of 'bestrophinopathies'. It has been shown previously that ADVIRC results from BEST1 mutations that cause exon skipping and lead to the production of shortened and internally deleted isoforms. This study describes a novel ADVIRC mutation and show that it disrupts an exonic splice enhancer (ESE) site, altering the binding of a splicing-associated SR protein. As with previous ADVIRC mutations, the novel c.704T-->C mutation in exon 6 altered normal splicing in an ex vivo splicing assay. Both this and another exon 6 ADVIRC-causing mutation (c.707G-->A) either weakened or abolished splicing in an ESE-dependent splice assay compared with a nearby exon 6 mutation associated with Best disease (c.703G-->C). Gel shift assays were undertaken with RNA oligonucleotides encompassing the ADVIRC and Best disease mutations with four of the most commonly investigated SR proteins. Although SC35, SRp40 and SRp55 proteins all bound to the wild-type and mutated sequences with similar intensities, there was increased binding of ASF/SF2 to the two ADVIRC-mutated sequences compared with the wild-type or Best disease-mutated sequences. The exon skipping seen for these two exon 6 ADVIRC mutations and their affinity for ASF/SF2 suggests that the region encompassing these mutations may form part of a CERES (composite exonic regulatory elements of splicing) site.

Three-color imaging using fluorescent proteins in living zebrafish embryos.

The zebrafish embryo is especially valuable for cell biological studies because of its optical clarity. In this system, use of an in vivo fluorescent reporter has been limited to green fluorescent protein (GFP). We have examined other fluorescent proteins alone or in conjunction with GFP to investigate their efficacy as markers for multi-labeling purposes in live zebrafish. By injecting plasmid DNA containing fluorescent protein expression cassettes, we generated single-, double-, or triple-labeled embryos using GFP, blue fluorescent protein (BFP, a color-shifted GFP), and red fluorescent protein (DsRed, a wild-type protein structurally related to GFP). Fluorescent imaging demonstrates that GFP and DsRed are highly stable proteins, exhibiting no detectable photoinstability, and a high signal-to-noise ratio. BFP demonstrated detectable photoinstability and a lower signal-to-noise ratio than either GFP or DsRed. Using appropriate filter sets, these fluorescent proteins can be independently detected even when simultaneously expressed in the same cells. Multiple labels in individual zebrafish cells open the door to a number of biological avenues of investigation, including multiple, independent tags of transgenic fish lines, lineage studies of wild-type proteins expressed using polycistronic messages, and the detection of protein-protein interactions at the subcellular level using fluorescent protein fusions.

Access to care among children visiting the emergency room with acute exacerbations of asthma.

To determine differences in access to continuing and preventive care among pediatric patients utilizing the emergency room for treatment of acute exacerbation of asthma, families of 170 asthma patients aged 2 to 17 years were surveyed prospectively. An interview schedule instrument generated information about socioeconomic factors, source of medical care including maintenance and specialty care, medication use, and plans for management of asthma exacerbations. A primary physician or clinic could be identified by 162 patients (95%). Regular preventive therapy (cromolyn, theophylline, or steroids) was used by 45 patients (27%). Allergy evaluations had been previously performed for 59 patients (35%). "Come to Emergency Room" was part of the asthma management plan for 56 patients (33%) and was the only asthma management plan for 34 patients (20%). Logistic regression analysis found that black and Hispanic patients (odds ratio = 0.38) and patients with Medicaid (odds ratio = 0.43) were less likely to call their MD or clinic prior to reporting to the emergency room. Patients with Medicaid were more likely to have two or more prior emergency room visits compared with a group of patients with private insurance and self-paying patients (odds ratio = 4.17). While the majority of patients in this study could identify a source of primary care, patients on Medicaid were significantly less likely to access continuing and preventive care and more likely to utilize the emergency room.

Buckwheat-induced anaphylaxis: a case report.

Buckwheat (Fagopyrum schulentum) is not taxonomically related to wheat and other cereal grains. Buckwheat flour is used as a wheat substitute in breads, biscuits, pancakes, and crepes. Occupational exposure to buckwheat flour has been associated with rhinitis, conjunctivitis, contact urticaria, and occupational asthma. We present a patient who developed urticaria and hypotension after ingestion of buckwheat crepes. Skin testing by the prick technique revealed 3+ positive reaction to buckwheat with negative reactions to other foods including wheat, egg white, and milk. RAST for anti-buckwheat IgE was strongly positive. Buckwheat ingestion is a potential cause of food-related anaphylaxis. There does not appear to be cross-reactivity between buckwheat and wheat allergy.

Internalization of monoclonal antibodies selected for immunotoxin activity against small-cell lung cancer.

Two hybridomas producing MOABs with anti-SCLC activity were selected for immunotoxin activity by an indirect screen and were twice cloned. Binding activity of the MOABs to SCLC cells was demonstrated by immunoperoxidase activity, which could be blocked by streptavidin. The MOABs mediated the internalization of a biotinylated Fab' anti-mouse Ig marker at 37 degrees C. Internalization of the biotinylated marker by the SCLC target cells resulted in protection of the marker from streptavidin-blocking. These results show that MOABs selected for immunotoxin activity against SCLC can mediate internalization of an antibody fragment with a mass about 50% greater than that of the toxin. MOABs selected for immunotoxin activity may be useful for delivering agents other than toxins to the inside of SCLC cells.

Urticaria and angioedema.

Urticaria and angioedema are commonly seen in the outpatient setting. Their pathogenesis involves complex cellular and humoral factors. Diagnosis depends on historical information such as duration of symptoms, exacerbating factors, and atopy. While many etiologic factors have been implicated, in most chronic cases no specific etiology is found. This article reviews physical and hereditary syndromes and discusses therapeutic regimens based on the duration and severity of symptoms.

Buckwheat-induced anaphylaxis: a case report.

Buckwheat (Fagopyrum schulentum) is not taxonomically related to wheat and other cereal grains. Buckwheat flour is used as a wheat substitute in breads, biscuits, pancakes, and crepes. Occupational exposure to buckwheat flour has been associated with rhinitis, conjunctivitis, contact urticaria, and occupational asthma. We present a patient who developed urticaria and hypotension after ingestion of buckwheat crepes. Skin testing by the prick technique revealed 3+ positive reaction to buckwheat with negative reactions to other foods including wheat, egg white, and milk. RAST for anti-buckwheat IgE was strongly positive. Buckwheat ingestion is a potential cause of food-related anaphylaxis. There does not appear to be cross-reactivity between buckwheat and wheat allergy.

Delayed nasal mucociliary clearance in patients with nonallergic rhinitis and nasal eosinophilia.

This study investigated nasal mucociliary clearance as related to nasal eosinophilia in nonallergic rhinitis patients using the technique of nasal saccharin challenge. Fifty-six consecutive patients with nonallergic rhinitis were evaluated with nasal cytology and saccharin challenge. A saccharin challenge time of greater than 25 minutes was considered abnormal. Twelve of 56 patients (21.4%) had nasal eosinophilia. Fifteen of 56 patients (26.8%) had prolonged nasal circulation times greater than 25 minutes, indicating delayed mucociliary clearance. Although 7 of 12 patients (58.3%) with nasal eosinophilia had delayed mucociliary clearance, only 8 of 44 patients (18.2%) without eosinophilia had circulation times longer than 25 minutes. The correlation of nasal eosinophilia with prolongation of the nasal circulation time is statistically significant (chi square 5.84, P = .0156). We postulate that damage to the nasal mucociliary system may be an etiologic factor for a subset of patients with nonallergic rhinitis and that this damage may be mediated by eosinophils.

Latex hypersensitivity: two case reports.

For persons hypersensitive to latex, continued exposure may result in a life-threatening situation. Since 1979 reports appeared supporting evidence of urticaria, rhinitis, asthma, and anaphylaxis in association with latex exposure. We present two cases of latex hypersensitivity, patients who reacted to latex on skin-prick and radioallergosorbent tests (RAST). A 30-year-old surgeon developed reactions to latex gloves. On skin-prick testing to latex extract in saline, he was 4+. RAST latex antigen-specific IgE was 50.75 times control. The second case is that of a 24-year-old nurse who underwent multiple corrective surgeries for congenital birth defects and experienced reactions to latex. On skin-prick testing to an extract of latex in saline, she was 2+. RAST latex antigen-specific IgE was 23.37 times control. Both patients were given epinephrine and diphenhydramine and advised to use latex-free gloves and to avoid latex products. As health care personnel contact with latex products increases because of new guidelines for the prevention of sexually transmitted diseases, more adverse reactions in this subpopulation will occur.