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Biomedical subjects

R Goldman

Publications and source records attributed to R Goldman.

At least 181 records · Page 10Linked to original sources
PubMed1977

Qualitative and quantitative aspects of lectin-induced vacuole formation in mouse peritoneal macrophages.

The binding, internalization, and vacuologenic activity of several native and chemically modified lectins was investigated on untreated and neuraminidase-treated mouse peritoneal macrophages. The distribution of lectin receptors on the cell surface and their internalization was assessed by employing both radioactive and fluorescent lectin derivatives. On the basis of their effect on the macrophages, the lectins tested can be divided into 2 categories: lectins that induce vacuole formation (concanavalin A, wax bean agglutinin, and wheat germ agglutinin), and lectins that do not induce vocuolation (soybean agglutinin, peanut agglutinin, and Lotus tetragonolbus agglutinin). Soybean and peanut agglutinins bound to macrophages only after neuraminidase treatment, but the latter treatment did not change the effect of other lectins on the cells. Glutaraldehyde-cross-linked polymers of soybean or peanut agglutinins, which are multivalent with respect to the number of sugar binding sites, induced vacuolation in neuraminidase-treated cells. On the other hand, succinylation of concanavalin A, which reduces the lectin's valence from 4 to 2 abolished its vacuologenic activity. While the data do not indicate direct correlation between vacuole induction and the number of lectin receptors or the extent of their internalization, they do suggest that multivalency of lectins is an important factor in vacuole formation. Multivalency of a lectin enables extensive cross-linkage of membrane receptors which may be a prerequisite for triggering vacuolation.

Concanavalin A↗
PubMed1976

Effects of local anaesthetics on intracellular fusion processes. Enhancement of concanavalin A-induced macrophage vacuolation.

The extensive vacuolation elecited in mouse peritoneal macrophages in response to interaction with concanavalin A is markedly enhanced by a simultaneous exposure to anaesthetics. The potency of enchancing vacuolation increases within the series of normal alcohols with chain length C10 greater than C8 greater than C7 greater than C6. From the four tertiary amine local anaesthetics tested lidocaine and procaine are by far more effective than tetracaine and dibucaine. The latter two induce extensive cell shrinkage at concentrations at which the first two exhibit optimum enhancing capacity. Of the tested compounds chlorpromazine has the highest membrane/buffer partition coefficient and it exhibits its optimum enhancing effect on concanavalin A-induced macrophage vacuolation at the lowest drug concentration. The binding of [3H] concanavalin A as well as its internalization by macrophages incubated with the lectin for 15, 45 and 90 min are not affected significantly in the presence of decanol, procaine or chlorpromazine at concentrations of maximum enhancing effect on vacuolation. Thus enhancement of vacuolation does not stem from an increase in the rate or extent of concanavalin A interiorization. The rate at which vacuoles are generated is however markedly increased in the presence of chlorpromazine and the resulting vacuoles are of a larger diameter. At 2-5 fold the concentration required for inhibition of maximum enhancing effect, the drugs lead to extensive macrophage shrinkage and to depletion of intracellular ATP. Phagocytosis of heat-killed yeast cells is reduced by tertiary amine anaesthetics at concentrations optimal for enhancement of concanavalin A-induced vacuolation. Enhanced intracellular fusion of concanavalin A-bearing pinosomes to form vacuoles is discussed in terms of current ideas on factors vacuoles is discussed in terms of current ideas on factors vacuoles is discussed in terms of current ideas on factors affecting membrane fusion and the effects of anaesthetics on membrane organization of lipids, intramembraneous particles, glycoprotein receptors and the possible control by cytoskeletal elements. The results best fit the hypothesis that enhanced fusion correlates with membrane aggregation of both intramembraneous particles and concanavalin A receptor and the formation of areas relatively deplete of these structures and enriched in phospholipids.

Adenosine Triphosphate↗
PubMed1976

The effect of hashish compounds on pphospholipid phase transition.

The interaction of hashish compounds, delta 1-tetrahydrocannabinol and cannabidiol, with dipalmitoyl phosphatidylcholine was investigated using differential scanning calorimetry. Both drugs affect the transition of dipalmitoyl phosphatidylcholine from the gel to liquid crystalline state, decreasing both the melting temperature and the enthalpy of melting. At a drug to dipalmitoyl phosphatidylcholine ratio of approx. 1:5, two peaks appear in the transition profile, suggesting a phase separation in the drug dipalmitoyl phosphatidylcholine mixture.

Binding Sites↗
PubMed1976

Differential effects of lipids on the osmotic fragility of lysosomes.

The effect of a wide range of concentrations of oleic acid, oleyl alcohol and oleic acid methyl ester on lysosomal stability has been studied under both hypotonic and isoosmotic medium conditions. Both oleic acid and oleyl alcohol exhibited a biphasic interaction pattern with lysosomes; stabilizing at low concentrations and labilizing at high concentrations. Lysosome labilization by the ester required an initial lag period.

Acid Phosphatase↗
PubMed1976

Effect of hashish compounds on mouse peritoneal macrophages.

Light microscopy reveals an induction of extensive vacuolation in the macrophage after exposure to either delta 1-tetrahydrocannabinol or cannabidiol. Numerous small vacuoles appear in the cell periphery as early as 15 minutes after exposure (at 37degrees C.) to either of the compounds in 20 per cent newborn calf serum-Dulbecco's modified Eagle medium. The small lucent vacuoles coaleasce and yield enormous vacuoles which dominate the the cytoplasm. At approximately 3 hours, many of the vacuoles seem to burst with a concomitant expulsion of cell interior. The effect of hashish compounds on macrophages is essentially irreversible; exposure for 15 minutes to 10(-5) m of delta 1-THC or cannabidiol and a thorough wash in 20 per cent serum-medium, suffices to trigger the sequence of vacuolation and total cell death in the culture. Two major processes involving early reorganization of cellular membranes have been observed using electron microscopy. One relates to the formation of numerous autophagic vacuoles full of organelles, the other relates to the appearance of cytoplasmic inclusions representing extensive destruction of intracellular constituents. Both types of cytoplasmic change have been observed in alveolar macrophages of hashish smokers. Thus, the conditions in the in vitro studies are similar to conditions in people exposed to hashish smoke.

Animals↗
PubMed1975

Assessment of various auditory perceptual and cognitive skills.

Certain questions regarding auditory skills that are of interest to both researchers and clinicians are raised. These questions have been translated into procedures for assessment of various auditory abilities, resulting in a battery of standardized tests. The main categories of listening skills that are measured are selective attention, auditory discrimination, auditory memory and operations with sounds and/or symbols. The information derived from this battery is discussed in terms of implications for diagnosis and for educational and therapeutic intervention.

Auditory Perception↗
PubMed1975

Another dimension for assessment of speech-sound discrimination: latency of response.

The relationship of speech-sound-discrimination skills and speed of responding was investigated by presenting monosyllabic nouns in three different listening conditions to a total of 72 nursery, kindergarten, and first-grad children divided into three equal-sized groups. Speed of responding was related to the age of subjects, accuracy of responding, and context of presentation of stimulus items. There was a consistent decrease in latency of responding as age increased. Error responses had greater response latencies than correct responses. Response latencies for different contexts of presentation of stimulus items were longest for the paired-comparison context and shortest for the carrier-phrase context. Speed of responding could be considered as an additional parameter when evaluating speech-sound-discrimination skills.

Age Factors↗