A histological and immunohistochemical study of the effects of N-acetyl cysteine on retinopathy of prematurity by modifying insulin-like growth factor-1

Retinopathy of prematurity (ROP) is a vasoproliferative disorder that occurs in premature infants and may lead to permanent visual impairment. We investigated both the possible protective role of N-acetyl cysteine (NAC) for preventing ROP and the role of IGF-1 in the disorder. Forty-five newborn rats were divided into three groups. Group 1 was raised in room air as controls. Group 2 was exposed to 60% oxygen for 14 days after birth, then transferred to room air. Group 3 was exposed to the same conditions as group 2, but received intraperitoneal injections of NAC on postnatal days 7–17. After 35 days, both eyes of all rats were processed for histology. Some sections were stained with hematoxylin and eosin to assess structural changes and other sections were immunostained to determine the location of IGF-1. Frozen sections also were prepared and stained for adenosine triphosphatase to detect retinal blood vessels. Compared to the controls, more blood vessels, many of which were abnormal, and increased IGF-1 expression were observed in group 2. In group 3, abnormal blood vessels and IGF-1 expression were less evident. NAC appeared to be an effective vascular-protective agent for ROP by decreasing IGF-1 expression.     

Interaction of vitronectin with collagen

Purified human plasma vitronectin was demonstrated to bind to type I collagen immobilized on plastic as measured by enzyme-linked immunosorbent assay and by binding of 125I-radiolabeled vitronectin to a collagen-coated plastic surface. Vitronectin did not bind to immobilized laminin, fibronectin, or albumin in these assays. Vitronectin showed similar interaction with all types of collagen (I, II, III, IV, V, and VI) tested. Collagen unfolded by heat treatment bound vitronectin less efficiently than native collagen. Vitronectin-coated colloidal gold particles bound to type I collagen fibrils as shown by electron microscopy. Salt concentrations higher than physiological interfered with the binding of vitronectin to collagen, suggesting an ionic interaction between the two proteins. Binding studies conducted in the presence of plasma showed that purified vitronectin added to plasma bound to immobilized collagen, whereas the endogenous plasma vitronectin bound to collagen less well. Although fibronectin did not interfere with the binding of vitronectin to native collagen, vitronectin inhibited the binding of fibronectin to collagen. These results show that vitronectin has a collagen-binding site(s) which, unlike that of fibronectin, preferentially recognizes triple-helical collagen and that the binding between vitronectin and collagen has characteristics compatible with the occurrence of such an interaction in vivo.     

Methods of Therapy in Alcoholism

Although the philosophy of the community mental health center has been applied to alcoholism since the early part of this decade, it has been pursued much more intensively in recent years, and there has been a decentralization in the management of alcoholics in a series of stages from the jail or work-house to the state hospital and to the clinic and the community. The medical practitioner now has opportunity to treat the alcoholic in private practice.Advances have been made in two directions. Advances in medical management have included reinforcement of the importance of hydration and electrolyte balance, particularly magnesium. Psychopharmacology has contributed three drugs particularly important in the management of acute alcoholism and its complications. These drugs are chlordiazepoxide, chlorpromazine, and thioridazine. Another drug, Antabuse, when properly used, has proven extremely valuable as a deterrent.Equally important have been administrative advances. The importance of the environment and its manipulation has been recognized, and a series of institutional and non-institutional resources, such as clinics, half-way houses, foster homes, and Alcoholics Anonymous has made it less likely that a patient will be turned away without help.     

Quantitative comparisons between the karyotypes of Australian marsupials from three different superfamilies

Relative DNA values and percent lengths of chromosome arms have been studied for six species of the super-family Dasyuroidea, five species of Phalangeroidea and four species of Perameloidea. By multiplying by relative DNA values all percent lengths have been expressed in the same units. Two species are said to share a chromosome if neither of the arms differs at the 5% level of probability. It is argued that if species share at least two two-armed chromosomes, this can be taken as evidence of relationship. A standard dasyurid karyotype has been defined and individual species of Dasyuridae show only small deviations from it. The nature and significance of the bi-modal distribution of chromosome numbers in marsupials is discussed.     

A myristylated form of the sea oncoprotein can transform chicken embryo fibroblasts

The transforming gene product of the S13 avian erythroblastosis virus, v-sea, is a member of the growth factor receptor class of tyrosine kinases. In the virus genome, the sea sequences are fused in frame to the virus env gene, thereby generating an abnormally large envelope protein because of the presence of a cytoplasmic tyrosine kinase domain. To determine what role these envelope sequences play in v-sea transformation, we generated a myristylated form of v-sea which contains no envelope sequences. In this report, we show that this myristylated sea-encoded protein retained the ability to transform chicken embryo fibroblasts, indicating that envelope sequences are not essential for transformation by the v-sea tyrosine kinase.     

Growth responses of mycorrhizal and non-mycorrhizal tropical forage species to different levels of soil phosphate

Three tropical forage legumes, Stylosanthes capitata, Pueraria phaseoloides and Centrosema macrocarpum, and one grass, Brachiaria dictyoneura, were grown in a sterile phosphate deficient soil amended with soluble or rock phosphate at rates ranging from 0 to 400 mg kg^-1 soil. The effects of inoculation with Glomus manihotis on mycorrhizal infection and plant growth were assessed. Early growth and nodulation of P. phaseoloides in soil with and without rock phosphate fertilizer were also determined. In the legumes, mycorrhizal infection was high at all P levels and sources, except for a significant decrease of infection in S. capitata at high levels of superphosphate. Plant growth was significantly increased by phosphate fertilizer and mycorrhizal inoculation. Mycorrhizal responses were more pronounced at low P levels with both P sources. In B. dictyoneura mycorrhizal infection was decreased with increasing additions of P. No effects of mycorrhizal inoculation (except with no added P) were observed. Growth and nodulation of P. phaseoloides were greatly stimulated by mycorrhizal inoculation.     

Ribosomal gene reiteration in a marsupial species with an X-linked nucleolar organizer

The number of ribosomal cistrons in somatic cells of males and females of Macropus eugenii have been estimated using RNA/DNA hybridization in 70% (v/v) formamide. The male has one X-linked active nucleolar organizer and the female two and while the number of ribosomal cistrons is variable between the four males examined (31-65 copies), it is substantially less than the number present in the three females (94-103 copies). There is, therefore, no evidence of dosage compensation by amplification.     

Effect of soil volume and plant density on mycorrhizal infection and growth response

Summary The effect of soil volume and plant density on mycorrhizal infection and growth response was studied with onion. There was a significant negative correlation between percentage vesicular-arbuscular mycorrhizal infection and root density. The growth response due to mycorrhiza decreased when less soil was available for the plant. The root: shoot ratio decreased with increasing plant density in both mycorrhizal and non-mycorrhizal plants. Pot size did not affect the root: shoot ratio.     

Conserved sequences in enzymes of the UDP-GlcNAc/MurNAc family are essential in hamster UDP-GlcNAc:dolichol-P GlcNAc-1-P transferase

The UDP-GlcNAc/MurNAc family of eukaryotic and prokaryotic enzymes use UDP-GlcNAc or UDP-MurNAc-pentapeptide as donors, dolichol-P or polyprenol-P as acceptors, and generate sugar-P-P-polyisoprenols. A series of six conserved sequences, designated A through F and ranging from 5 to 13 amino acid residues, has been identified in this family. To determine whether these conserved sequences are required for enzyme function, various mutations were examined in hamster UDP- GlcNAc:dolichol-P GlcNAc-1-P transferase (GPT). Scramble mutations of sequences B-F, generated by scrambling the residues within each sequence, demonstrated that each is important in GPT. While E and F scrambles appeared to prevent stable expression of GPT, scrambling of B- D resulted in GPT mutants that could be stably expressed and bound tunicamycin, but lacked enzymatic activity. Further, the C and D scramble mutants had an unexpected sorting defect. Replacement of sequences B-F with prokaryotic counterparts from either the B.subtilis mraY or E.coli rfe genes also affected GPT by preventing expression of the mutant protein (B, F) or inhibiting its enzymatic activity (C-E). For the C-E replacements, no acquisition of acceptor activity for polyprenol-P, the fully unsaturated natural bacterial acceptor, was detected. These studies show that the conserved sequences of the UDP- GlcNAc/MurNAc family are important, and that the eukaryotic and prokaryotic counterparts are not freely interchangeable. Since several mutants were efficiently expressed and bound tunicamycin, yet lacked enzymatic activity, the data are consistent with these sequences having a direct role in product formation.