Effects of retinoic acid (RA) on the growth and phenotypic expression of several human neuroblastoma cell lines

It has been shown that retinoic acid (RA) can promote morphologic differentiation and inhibit the growth of a human neuroblastoma cell line, LA-N-1. The present study tests the histological generality of these phenomena by determining the effects of RA on seven other human neuroblastoma cell lines. Results show that RA strongly inhibited anchorage-dependent growth and induced morphologic alterations in six of seven of the cell lines. These alterations included morphologic differentiation as evidenced by formation of neurite extensions in four of the lines, cellular enlargement and vacuolization in one culture, and formation of large, flattened epithelial or fibroblastic-like cells in another culture. Although one cell line was relatively insensitive to the effects of RA in monolayer culture, all seven were strongly inhibited by RA in soft agar assays. Cellular RA-binding proteins were detected in 2/2 lines tested. These findings suggest that, as a histological group, human neuroblastoma cells are extremely sensitive to RA-induced growth inhibition and morphological alterations generally associated with reduced expression of the malignant phenotype of this type of cancer.     

A specialised transducing phage of P22 for which the ability to form plagues is associated with transduction of the proAB region

Summary The multisite mutantproAB47 has been used to isolate specialised transducing phages of P22 for theproA andproB genes. Several of the preparations contain phages that form small plaques, and many of the properties of these suggest that the small plaques are formed by the transducing phages. Preliminary studies on the transduction of theproAB region by one such phage suggest that it forms fairly stable heterogenotes, both from apro point mutant and fromproAB47. The fact that the latter mutant is missing the phage attachment site results in a delay in integration of the specialised transducing phage.     

Folate Status Throughout Pregnancy and in Postpartum Period

The serial trends of the whole blood folate level in two groups of patients have been followed throughout pregnancy and up to six weeks postpartum. In those receiving iron alone the whole blood folate remained normal until the test at six weeks after delivery, at which time over half were in the deficient range. There appears to be a delay before this test reflects the current folate status when this changes rapidly. In those receiving iron plus 330 μg. of folic acid a day the results at this time were close to those at the beginning of pregnancy. Subnormal whole blood folate, red cell folate, and serum folate values occurred close to term in patients receiving iron alone, but were not found in those also receiving folic acid. Megaloblastic changes occurred at term in three patients receiving iron alone in whom the whole blood folate had repeatedly been low in early pregnancy.The observations are consistent with the previous suggestion that 300 μg. of folic acid daily is a suitable supplement to prevent deficiency in late pregnancy and the puerperium.     

Oesophagoscopy,biopsy, and acid perfusion test in diagnosis of "reflux oesophagitis".

The results of fibreoptic endoscopy have been assessed retrospectively in 71 patients referred for consideration of the oesophagus as the possible or probable cause of their symptoms. Gross endoscopic abnormality was uncommon but friability of the mucosa was seen in about half of the patients with typical symptoms of "reflux-pain" and a quarter of those without. The combination of radiological reflux and endoscopic abnormality--that is, true reflux oesophagitis--was seen in only a third of the patients with typical symptoms though much less commonly in those with atypical symptoms. Histological abnormality was common but did not relate well to symptom pattern. The results of the acid perfusion test were significantly related to symptom pattern though overlap was observed between the two symptomatic groups. Six of these patients had had or were awaiting surgery to correct reflux and they all had uniformly positive findings. This study confirms the value of the acid perfusion test in clarifying the diagnosis of reflux pain, espcially if the symptoms are difficult to assess. Endoscopy and biopsy added little further information of diagnostic value and could probably be reserved for the small minority of patients who have special problems such as blood loss or dysphagia or where clarification of a radiological lesion is required.     

Immune status of children with and without severe infection during remission of malignant disease.

The immune status of children with malignant disease in remission was assessed usingvarious immune function tests. Children with infections had significantlymore neutropenia, hypogammaglobulinaemia, and impaired cell-mediated immune responses than those without. These two groups combined had much more absolute lymphopenia and impairment of both cell-mediated immunity and antibody-producing capacity thancontrol children with non-malignant conditions. Regular immunological evaluation isrecommended for children with malignant disease when new intensive treatment schedules are under trial and for individual patients particularly prone to develop infections during treatment.     

The effect of T lymphocyte deficiency on tumor induction and growth

Severe reduction in the numbers of T lymphocytes as occurs in thymectomized, X-irradiated, bone marrow reconstituted mice or nude mice did not increase the animals susceptibility to chemical carcinogenesis. However, once established, many tumors grew distinctly slower in the T cell deficient animals. This was demonstrated to be due to lack of normal T cell function since tumors arising in TXB hosts progressed much faster in normal secondary hosts than in secondary TXB hosts. In most instances, established tumor cell lines from tissue culture also grew more slowly in T deficient hosts. The suggestion was made that T cells may not be required for immune surveillance while the immune mechanism(s) that promote subsequent tumor growth are T cell dependent. Alternative possibilities are discussed.     

Scutoid mutation of drosophila melanogaster specifically decreases olfactory responses to short-chain acetate esters and ketones

A molecular-genetic approach has been taken to identify genes involved in olfactory transduction in Drosophila melanogaster. Two independent lines of research led to the finding that the dominant Scutoid (Sco) mutation causes a diminshed extracellular electroantennogram response to the odorants ethyl acetate (EtAC) and acetone (AC). Sco flies showed about 4- and 2.5-fold reduced responses to EtAC and AC, respectively, compared to Canton-S wild-type and sibling control flies lacking the Sco mutation when electroantennogram recordings were made from the proximal anterior third antennal segment. The responses to five other odors from three different chemical classes were unaltered. The maximum response to either EtAC or AC was decreased with no change in apparent affinity. Responses to short-chain (but not long-chain) acetate esters and ketones were dramatically affected at all antennal locations tested. Only in the proximal quadrants were responses to ethyl acetoacetate also reduced. Most Sco revertants tested had a normal olfactory response; duplications of the region including no-ocelli partially suppress the Sco bristle as well as olfactory phenotypes. Sco adults had an impaired behavioral response to EtAC but not to banana or propionate. There was no effect of the mutation on larval chemosensory behavior or extracellularly recorded adult compound eye and ocellar visual responses. These findings suggest the involvement of Sco in an olfactory pathway in adults which is specific for short-chain acetate esters and ketones. © 1995 John Wiley & Sons, Inc.     

An S-RNase promoter from Nicotiana alata functions in transgenic N. alata plants but not Nicotiana tabacum

Nicotiana tabacum and Nicotiana alata plants were transformed with genomic clones of two S-RNase alleles from N. alata. Neither the S ₂ clone, with 1.6 kb of 5 sequence, nor the S ₆ clone, with 2.8 kb of 5 sequence, were expressed at detectable levels in transgenic N. tabacum plants. In N. alata, expression of the S ₂ clone was not detected, however the S ₆ clone was expressed (at low levels) in three out of four transgenic plants. An S ₆-promoter-GUS fusion gene was also expressed in transgenic N. alata but not N. tabacum. Although endogenous S-RNase genes are expressed exclusively in floral pistils, the GUS fusion was expressed in both styles and leaves.     

Modulation by Ionotropic Excitatory Amino Acids and Potassium of (±)-1-Aminocyclopentane-trans-1,3-Dicarboxylic Acid-Stimulated Phosphoinositide Hydrolysis in Mouse Cerebellar Granule Cells

Abstract: The effect of ionotropic excitatory amino acids and potassium on the formation of inositol phosphates elicited by the metabotropic glutamate receptor agonist (±)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD) was studied in mouse cerebellar granule cells. In Mg²⁺-containing buffers, NMDA (50–100 µM), α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA; 10–1,000 µM), and high potassium (10–30 mM) enhanced synergistically the response to a maximally effective concentration of 500 µMtrans-ACPD. Potentiation of the trans-ACPD response was blocked by higher concentrations of NMDA (>500 µM) and potassium (>35 mM) but not by AMPA (up to 1 mM). The potentiation by NMDA of the trans-ACPD-stimulated phosphoinositide hydrolysis was blocked by d,l -2-amino-5-phosphonopentanoic acid (APV), a competitive NMDA-receptor antagonist. Under Mg²⁺-free conditions, the accumulation of inositol phosphates in the presence of trans-ACPD alone was equal to that attained by trans-ACPD in Mg²⁺-containing buffers when costimulated with maximally enhancing concentrations of NMDA (50 µM). trans-ACPD potentiated synergistically the NMDA-evoked increases in cytosolic free-Ca²⁺ levels in Mg²⁺-containing but not in Mg²⁺-free solutions, and moreover did not enhance the AMPA-evoked increases in cytosolic free-Ca²⁺ levels. The calcium ionophore A23187 caused a dose-dependent increase in inositol phosphate accumulation but did not enhance the response stimulated by trans-ACPD alone. These results demonstrate the existence of cross talk between metabotropic and ionotropic glutamate receptors in cerebellar granule cells. The exact mechanism remains unclear but appears to involve interplay of G protein-coupled phospholipase C activation and regulated elevation of cytosolic free-Ca²⁺ levels. This study may provide a framework for future investigations at the cellular and molecular level that clarify the functional relevance and molecular mechanisms that are described.