Use of fluorometry in assessing the efficacy of a cation-sensitive gel as an ophthalmic vehicle: comparison with scintigraphy.

Gelrite, a heteropolysaccharide that forms a gel in the presence of cations, was tested in humans for its efficacy as an ophthalmic vehicle by a nonivasive fluorometric technique. Fluorescein was used as the tracer, and its concentration in the anterior chamber was used as the principal measure of bioavailability. The gel afforded a twofold increase in penetration of fluorescein compared with an isotonic buffer solution; this increase is slightly more than can be obtained with simple viscous vehicles. The increase in penetration caused by Gelrite was confirmed by measurements of the contact time of fluorescein in the tear film with the cornea. Earlier experiments with scintigraphy suggested a considerably greater contact time of fluorescein with the cornea when Gelrite was used. However, this increased contact time may be because the technique also measures radioactive tracer that had dried out on the lid margins. Accordingly, significant quantities of fluorescein could be eluted from the lids after the penetration experiments were completed.     

Cytogenetic diagnosis using midtrimester fetal blood samples: Application to suspected mosaicism and other diagnostic problems

Cytogenetic studies on fetal blood cells obtained at 18–25 weeks gestation have provided information for decision making in 25 cases identified as being at high risk of having an abnormal fetus. In particular, in the 21 cases studied to consider the possibility of true mosaicism, confirmation in fetal blood was obtained in three, one of which presented as a pseudomosaic on the original amniotic fluid cell study. Fetal blood was also informative in two cases (one positive and the other negative) in which a diagnosis of the fragile X syndrome was being considered. Furthermore, when high risk pregnancies presented late in gestation (21–24 weeks), these methods allowed for a rapid cytogenetic diagnosis. The procedure has proved useful in most of these cases since the couples involved had indicated that they would probably have terminated the pregnancy without the reassurance of normal fetal lymphocyte studies. Since the technique carries a much higher risk of pregnancy loss than does amniocentesis, its use should only be considered when there are compelling indications.     

The location of the fluid pump in the cornea

1. Fluid transport across rabbit corneal tissue has been investigated by observing the movement of fluid interfaces under the microscope, or by mounting the tissue between two chambers and observing the displacement of menisci within capillary tubes.2. In both cases, the endothelial layer supported on a thin sheet of connective tissue is capable of pumping fluid in a direction out of the cornea, against a head of pressure. The volume of fluid moved may amount to twelve times the thickness of the endothelial cells in an hour.3. This active fluid movement accounts for the prevention of swelling of the normal corneal stroma. The hypothesis that corneal hydration is regulated by the sodium pump in the epithelial layer is not supported by these experiments.     

OH treatment of tetanus toxin reduces its susceptibility to limited proteolysis with more efficient presentation to specific T cells

At inflammatory sites, before their processing, antigens are exposed to oxygen free radicals released by activated cells. The effect of hydroxyl radicals (OH·) on the structure of a protein antigen, tetanus toxin (TT) was investigated, as well as the consequences on processing and presentation. A chemical system composed of Fe-EDTA, ascorbate and H₂O₂ was used to produce physiological amounts of OH^• radicals. TT exposed to OH· radicals presented a marked decrease of its intrinsic fluorescence with a concomitant increase of the content of bityrosine, but no fragmentation of the protein was detected by SDS-PAGE. Processing of the modified TT was analysed, by incubating TT at acidic pH with fractions enriched in plasma membranes and lysosomes obtained from a lymphoblastoid cell line (LCL). Proteolysis of OH·-treated TT was less important than proteolysis of native TT, especially upon prolonged incubations. Oxidized TT presented by LCL cells induced a greater proliferation of three different TT specific T cell clones, compared to native TT. When proteolytic digests of TT were presented by fixed LCL cells to a homologous T cell line, the proliferative response obtained in the presence of digests of OH·-treated TT was sustained, even in the case of prolonged proteolysis, whereas the response to digests of native TT fell rapidly. The relative resistance of OH·-treated TT to proteolysis appears thus responsible for its greater presentation to specific T cells, probably by protecting epitopes.     

Schizophrenia and Evoked Potentials: Maximum Amplitude, Frequency of Peaks, Variability, and Phenothiazine Effects

The purpose of this study was to compare averaged visual evoked potentials AVEPs) in normal subjects and in schizophrenics off and on phenothiazine medication. Flashes of 4 intensities were used. Ss were tested 3 times within a 1 month period. Measures of maximum amplitude (Am), frequency of peaks I FOP), and variability (V) were obtained- With increases in stimulus intensity all Ss showed increases in Ams and decreases in FOPs and V. Schizophrenics had smaller Ams. greater FOPs, and grear V than normals. Schizoprenies on phenothiazines generally had less FOPs initially and after 1 wk mi medication but not after about I month on medication. There was no consistently significant effect of phenothiazines on maximum amplitude. NO drug effect on variability was observed. Schizophrenics showed a decrease in FOPs over time while normals showed an increase. A relationship was found between variability and overall thought disturbance. Changes in clinical condition over a month were not associated with discernible AVEP changes. Relationships between Am, FOP, unit V are presented.     

Diagnostic value of anti-Saccharomyces cerevisiae and antineutrophil cytoplasmic antibodies for inflammatory bowel disease: high prevalence in patients with celiac disease

Both celiac disease and inflammatory bowel disease (IBD) are characterized by chronic diarrhea and the presence of distinct (auto)antibodies. In the present study we wanted to determine the prevalence of serological markers for inflammatory bowel disease, i.e., perinuclear antineutrophil cytoplasmic antibodies (pANCA) and/or anti-Saccharomyces cerevisiae antibodies (ASCA), in 37 patients with biopsy-confirmed celiac disease (Marsh IIIb/c). The majority of the patients was positive for IgA (auto)antibodies typically associated with celiac disease, i.e., antiendomysium antibodies (EMA) (86.5%), antigliadin antibodies (AGA) (73%), and antirecombinant human tissue transglutaminase antibodies (rh-tTGA) (86.5%). Four patients with selective IgA deficiency could be identified by analyzing EMA, AGA, and rh-tTGA for the IgG isotype. The prevalence of pANCA and ASCA, markers that are used for IBD, was unexpectedly high in our cohort of patients with celiac disease: 8 patients were positive for pANCA (IgG) and 16 patients were positive for ASCA (IgG and/or IgA). These results indicate that the presence of pANCA or ASCA in the serum of patients with chronic diarrhea does not exclude celiac disease. A prospective study is required to determine whether pANCA and/or ASCA identify patients at risk for developing secondary autoimmune disease.     

Stability of intracranial self-stimulation following hypophysectomy

The possibility of a hypothalamo-pituitary involvement in the intracranial self-stimulation phenomenon was investigated. Threshold and optimal stimulation currents were identified by means of the method of limits, in rats with bipolar electrodes implanted in the lateral hypothalamus. Total or sham hypophysectomies were performed after the establishment of these current values, and found to have no effect on reinforcing brain stimulation. It was concluded that a hypothalamo-pituitary mechanism does not subserve reinforcing brain stimulation.     

Presence of a linear plasmid-like DNA molecule in the fungal pathogen Ceratocystis fimbriata Ell. & Halst.

Summary A plasmid-like molecule was detected in a strain of the ascomycete Ceratocystis fimbriata Ell. & Halst., a pathogenic fungus of Populus spp. The DNA replicon, designated pFQ501, was found to have a linear structure with a length of 6.0 kb (3.9 × 10⁶ daltons) and a density of 1.685 g/cc. This molecule was found to be associated with the mitochondria and was isolated from the gel; its restriction map was deduced from single and double digestions.