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Biomedical subjects

B Schwartz

Publications and source records attributed to B Schwartz.

At least 289 records · Page 16Linked to original sources
PubMed1987

Nerve fiber layer photography. A comparative study.

Observation of the retinal nerve fiber layer with red-free light is an important means of evaluating optic nerve integrity. Many investigators have attempted to increase the usefulness of the technique by improving photographic procedures. Most reports comparing various parameters neither indicate the method of comparison nor give quantitative measure of the improvement gained with different films, filters, cameras, or processing procedures. We have compared in a masked fashion the parameters most recently recommended in the literature. Twelve trained observers compared 12 masked pairs of nerve fiber layer photos taken from the same eye in the same manner on two cameras and preferred those taken with a Canon CF-60Z camera 69% of the time and those taken with a Zeiss FF-111 17% of the time (this difference was statistically significant, P less than 0.01). Fourteen observers compared 14 pairs of photographs and judged Panatomic-X film to be superior to Plus-X film 51% of the time and both films to be of the same quality 25% of the time (this difference was also significant P less than 0.05). Fifteen observers compared 12 pairs and preferred the Standard SE-40 blue filter 2:1 over the green Spectrotech 540 filter. This difference was not statistically significant, and the preference was found to be dependent on fundus pigmentation and clarity of the media. The blue filter gave better contrast for the nerve fiber layer in patients with lightly pigmented fundi, and use of the green filter resulted in less light scatter in patients with ocular media opacities.

Evaluation Studies as Topic↗
PubMed1987

Level of indoor allergens in dust from homes of allergic and non-allergic individuals.

In a number of studies performed on different locations throughout the world and in homes inhabited both by healthy individuals as well as by patients allergic to the specific allergen, the content of the major allergens from the house dust mite (Der p I, m I and f I), cat (Fel d I) and dog (Ag 3, 13) was measured. The comparison between homes of allergics and non-allergics revealed a tendency to high levels of cat allergens in homes of non-allergics. The content of the mite allergens showed large variations both with respect to the total amount of mites and the species of the mites.

Allergens↗
PubMed1987

Steroid potentiation of beta-adrenergic-sensitive adenylate cyclase in rabbit ciliary processes.

Dexamethasone (3.3 X 10(-8) M) potentiated 1-isoproterenol-stimulated adenylated cyclase activity in vitro in rabbit ciliary process epithelial membrane preparations. The ka for isoproterenol stimulation of the cyclase was 5 X 10(-7) M in control membranes, 2.5 X 10(-9) M in membranes preincubated with dexamethasone, and 6 X 10(-8) M with corticosterone. No change was observed in basal adenylate cyclase activity. Changes in enzyme activity at maximally stimulating levels of isoproterenol were not consistently different. Dose response to corticosterone in the presence of 10(-7) M 1-isoproterenol shows maximum effect at 6.6 X 10(-8) M corticosterone.

Adenylyl Cyclases↗
PubMed1987

Serum pseudocholinesterase in state anxiety.

Levels of serum pseudocholinesterase in 14 medical students before and after oral examinations in psychiatry were compared. Blood samples were collected 1 hour before and 2 to 4 weeks after the oral examinations. Serum pseudocholinesterase was significantly higher in state anxiety than in relaxation. The relation between state anxiety and high levels of this enzyme was established. No significant difference was observed in pseudocholinesterase levels between students with physiologic anxiety symptoms and those without.

Adult↗
PubMed1986

Increased diameter of the anterior ciliary artery with increased intraocular pressure.

We analyzed the relationship between the hemodynamics of the anterior ciliary artery and intraocular pressure (IOP) by measuring the pressure of the artery with a modified pressure chamber method and the diameter of the artery on color photographs taken with a photo slit lamp (Zeiss). Of 38 subjects, nine were normal, and 29 were ocular hypertensive. We found a significant positive correlation between diameter of the anterior ciliary artery and IOP and a significant negative correlation between pressures of the anterior ciliary artery and IOP. The increase in IOP may influence the circulation of the anterior uvea, resulting in a decrease in anterior ciliary arterial pressure and an increase in diameter of the anterior ciliary artery. Our results support the concept that the blood flow in the anterior ciliary artery is from the inside of the eye to the outside.

Adult↗
PubMed1986

Indoor allergens.

Explore the source record for details and available documents.

Air Pollutants↗
PubMed1986

Clinical and laboratory evaluation of cytomegalovirus-induced mononucleosis in previously healthy individuals. Report of 82 cases.

The present report describes the clinical and laboratory profile of 82 previously healthy individuals who developed cytomegalovirus (CMV)-induced mononucleosis. Many of these patients posed initial diagnostic problems and were hospitalized with diagnoses such as fever of undetermined origin, active viral hepatitis, acute leukemia, probable systemic lupus erythematosus, autoimmune hemolytic anemia, and severe pancytopenia. These patients underwent a variety of diagnostic biopsies, including liver biopsies (6) and bone marrow aspirations (9). Four patients had exploratory laparotomies, 1 for a ruptured spleen, and another had a splenectomy following an erroneous initial diagnosis of agnogenic myeloid metaplasia. There was no apparent clinical response to a short course of steroid therapy in 3 of 5 cases and acyclovir in another. The vast majority of these patients demonstrated infectious mononucleosis-type reactive blood smears, negative heterophil antibody studies, mildly or moderately elevated aspartate aminotransferase activity, and evidence for subclinical hemolysis on serial specimens. The peak serum bilirubin levels were above 2.0 mg/dl in only 2 of 71 cases tested, both of the latter patients having significant hemolysis (hemoglobin values 8.6-9.3 g/dl). The CMV-IgM test had a high sensitivity for detection of CMV macroglobulins (positive in 81 of 82 cases). In contrast, complement-fixing antibodies to CMV showed diagnostic four-fold titer changes in only 39/82 cases (47.6%). Despite its great sensitivity, the CMV-IgM test is limited by a one-way crossreaction of acute Epstein-Barr virus (EBV)-IM sera and spurious positive reactions in some sera due to the presence of rheumatoid factors. Based on EBV-specific serologic studies, the 82 patients with CMV-IM could be divided into 4 groups: 3 patients without antibodies to EBV; 2) 69 patients with uncomplicated serologic data indicative of long-past EBV infections; (3) 6 patients with unusual antibody profiles, e.g., anti-D responses; and (4) 5 patients, including 1 originally susceptible to EBV, with apparent dual CMV/EBV infections. At the conclusion of our study, final diagnoses and initial hematologic data were correlated in 750 cases in which CMV macroglobulins were searched for. The vast majority of patients with active CMV infections initially demonstrated either markedly or moderately reactive peripheral blood smears. These data support our impression that diagnostic tests for CMV, as well as for EBV, are seldom indicated in symptomatic previously healthy patients whose blood smears during the acute phase (first several weeks) of their illnesses are either nonreactive or minimally reactive.

Adolescent↗
PubMed1986

Allergen-specific IgE antibodies against antigenic components in cow milk and milk substitutes.

Crossed radioimmunoelectrophoresis (CRIE) was used to study the presence of serum IgE against antigenic components of cow milk in 21 selected milk-allergic patients. The amount of each IgE specificity was estimated by a scoring system. The milk-allergic children had mainly IgE against alpha-lactalbumin, beta-lactoglobulin, albumin and immunoglobulin, the four major proteins of bovine whey, as well as IgE against three casein components. A serum pool from 1000 normal adults had IgE against the same whey protein, but in smaller amounts, and no IgE against the casein components. Eight cow milk-based formulae, commonly used for infant feeding, and goat milk were studied by the same method. It was found that six of the milk substitutes did not differ significantly from cow milk in antibody binding, but the two hydrolysed casein products, Nutramigen and Pregestimil, consisted of such small molecules that the rabbit antisera could not precipitate the hydrolysed proteins in the gels on the CRIE plates. It was therefore not possible to study their IgE binding, if any, by this method.

Adult↗
PubMed1986

Specific diagnosis of exogenous bronchial asthma in children.

Twenty-six children with exogenous asthma were studied by case history (CH), skin tests (ST), allergen-specific serum IgE (RAST), basophil histamine release (HR), and bronchial provocation tests (BPT). Nine standardized allergens were used from the following groups: house dust mite, animal dander, pollen, and mould fungi. For each allergen, the same batch was used throughout for all in vivo and in vitro studies, and the tests were carried out in a controlled, double-blinded manner, independent of each other. Different allergen concentrations were used and the results graded on a semi-quantitative scale. Approximately 120 comparable investigations, using in vivo and in vitro tests were carried out, followed by calculations of the sensitivity and specificity for each test alone, as well as for various combinations of tests, at various allergen-concentrations, and compared with the result of BPT, i.e. the true diagnosis. In this way the results could be used to directly compare the diagnostic value of each test, and combinations of tests. In general, a careful CH combined with ST gave the most reliable results. RAST was the most unreliable single analysis. When pollen or mite allergy was suspected, a combination of ST with either RAST or HR gave a further diagnostic reliability. HR as a single analysis did not seem to offer advantages over existing methods. None of the tests, or combinations of tests offered 100% sensitivity and specificity. By altering the concentration of allergen, the sensitivity, or specificity could be increased, but only at the expense of a decrease in the other. BPT is still necessary in many instances when a specific diagnosis is required.

Adolescent↗
PubMed1986

Computerized enhancement of retinal nerve fiber layer.

We investigated a number of image processing techniques for enhancing the retinal nerve fiber layer (NFL) in fundus photographs taken with red-free light. Wedge-type defects within the NFL were enhanced best by contrast enhancement algorithms such as histogram modification and extremum sharpening. Narrow, slitlike NFL defects can be enhanced by directional enhancement techniques. Normal NFL features were enhanced best by high-pass filtering techniques such as homomorphic filtering and adaptive enhancement. The enhanced normal NFL may be useful in the analysis of diffuse NFL loss. All of these successful enhancements of normal and defective features indicate that enhancing fundus photographs with digital image processing techniques should facilitate early detection of optic nerve damage from glaucoma and other diseases.

Computers↗
PubMed1986

Allocation of complex, sequential operants on multiple and concurrent schedules of reinforcement.

Pigeons could produce food by pecking exactly four times on each of two keys, in any order. In the first experiment, these response sequences were reinforced on a series of multiple schedules of variable-interval reinforcement. In the second experiment, these response sequences were reinforced on a series of concurrent schedules of reinforcement. In both experiments, highly stereotyped response sequences developed. If these response sequences were treated as individual responses, the resulting data conformed to what is typically reported in studies of multiple and concurrent schedules involving individual responses. For example, behavioral contrast was observed with the multiple schedules, and matching was observed with the concurrent schedules. However, schedule manipulation had no effect on within-sequence characteristics of responses like accuracy, stereotypy, or rate. These data constitute further evidence that response sequences can become functional behavioral units.

Journal Article↗
PubMed1986

Role of cyclic GMP in gastrin secretion from rat antral mucosae in organ culture.

Rat antral mucosae maintained for 6 h in organ culture responded to carbamylcholine with a significant increase in endogenous cyclic GMP production and gastrin secretion. The acetylcholine analogue exerted a stimulatory action within a defined concentration range: exposure of antral explants to carbachol concentrations greater than the optimal stimulatory dose was accompanied by a marked decrease in both cyclic GMP production and gastrin release. Exogenous 8-Br-cyclic GMP (1 mM) significantly augmented gastrin secretion into the culture media during 6-12 h culture periods. Cycloheximide (0.1 mM) and the Ca2+ channel-blocker verapamil (5 microM) prevented 8-Br-cyclic GMP from acting as a gastrin secretagogue. Addition of cyclic somatostatin-14 (0.1 mM) to culture media was attended by complete inhibition of 8-Br-cyclic GMP-stimulable gastrin secretion. These results provide evidence that cyclic GMP may play a mediatory role in the coupling of gastrin secretory processes to agonist stimulation. It would seem that the secretagogue action of 8-Br-cyclic GMP requires unabated Ca2+ transmembrane fluxes and protein biosynthesis. Since somatostatin-14 abrogates the stimulatory effect of 8-Br-cyclic GMP on antral gastrin secretion, it is surmised that the inhibitory tetradecapeptide acts at a locus (or loci) distal to domains involved in the actual generation of the cyclic nucleotide.

Animals↗
PubMed1986

Effect of amino acid input rates on lens metabolism in a perfusion culture system.

A perfusion system has been established for the organ culture of the lens. The system is designed so that a constant flow of fluid occurs past the lens and a separate channel of fluid simultaneously bypasses the lens. Lens metabolic activity can be determined by analyzing differences between these two samples of fluid. The system also maintains a level of pressure comparable to intraocular pressure. Apparatus for observation and photography of the lens is built into the system. The purpose of these studies was to determine if this perfusion system could maintain the rabbit lens close to the physiological state, to study the metabolic behavior of the lens under steady state conditions, and to determine the effect of increasing amino acid concentrations on the metabolic activity of the lens under steady state conditions. By increasing the amino acid concentrations in the medium we hoped to compensate for the lack of protein in the medium and to provide metabolic substrate to maintain the lens under perfusion conditions. The rabbit lens was cultured at a temperature of 33 degrees C for periods up to 100 h. A totally synthetic perfusion medium without proteins or antibiotics was devised. This medium imitates posterior chamber aqueous humour, except that it does not contain ascorbic acid because it was found that ascorbic acid readily auto-oxidizes and depletes the oxygen content of the medium. The amino acid concentration of the perfusion medium was adjusted so that its total nitrogen content was equivalent to the total nitrogen content of posterior chamber aqueous humour. To determine the metabolic behavior of the lens, 10 different metabolic substances were analyzed in the medium and 15 were analyzed in the lens. These substances are mainly metabolic substrates and end products. As a reference for the evaluation of the behavior of the lens in the perfusion system, the perfused lens was compared to the lens in the other eye of the rabbit. Standards for differences between the right and left lens and the first or second lens removed from the rabbit were developed in control studies. A series of experiments was devised to determine the effect of increased amino acid concentration in the medium on the metabolic behavior of the lens. Concentrations of amino acids from 0 to 7.26 times the posterior concentration of amino acids in chamber aqueous humour were studied. Seven studies were done with a flow rate of medium of about 2 g per h, with each experiment lasting from 80 to 100 h.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗