Night eating and its relationship with BMI, stress, sleep quality and duration of study among university students.

INTRODUCTION: Night eating is a very common dietary behaviour among university students. This study aims to investigate the relationship between night eating and BMI, stress, sleep quality and duration of study among university students. MATERIALS AND METHODS: A total of 385 university students including foundation and undergraduate students took part in this study. Self-administered online surveys were used to obtain sociodemographic data, and anthropometry measurements including weight and height, night eating during studying, duration of the study, opinion on eating and academic performance, sleep quality, level of depression, anxiety, and stress of the respondents. Questionnaires were validated and IBM SPSS Statistics Software version 26.0 was used to analyse categorical and continuous variables. RESULTS: The findings showed that there was an association between night eaters and coffee consumption with BMI (p<0.001) and sleep quality (p<0.05). However, there was no association (p>0.05) found between the types of food eaten during night studying and the mean duration of the study. The results showed drinking coffee had an association with depression, anxiety, and stress (p<0.05) among Malaysian university students. CONCLUSION: Coffee consumption was common among undergraduate students during studying. Awareness of the risk of overconsumption of caffeine intake should be implemented in the future. However, this study did not include all types of food choices and drinks. Thus, frequency of eating energy dense food during night studying among students should be conducted in the future.

Islamic Perspectives on Polygenic Testing and Selection of IVF Embryos (PGT-P) for Optimal Intelligence and Other Non-Disease-Related Socially Desirable Traits.

In recent years, the genetic testing and selection of IVF embryos, known as preimplantation genetic testing (PGT), has gained much traction in clinical assisted reproduction for preventing transmission of genetic defects. However, a more recent ethically and morally controversial development in PGT is its possible use in selecting IVF embryos for optimal intelligence quotient (IQ) and other non-disease-related socially desirable traits, such as tallness, fair complexion, athletic ability, and eye and hair colour, based on polygenic risk scores (PRS), in what is referred to as PGT-P. Artificial intelligence (AI) and machine learning-based analysis of big data sets collated from genome sequencing of specific human ethnic populations can be used to estimate an individual embryo's likelihood of developing such multifactorial traits by analysing the combination of specific genetic variants within its genome. Superficially, this technique appears compliant with Islamic principles and ethics. Because there is no modification of the human genome, there is no tampering with Allah's creation (taghyir khalq Allah). Nevertheless, a more critical analysis based on the five maxims of Islamic jurisprudence (qawa'id fiqhiyyah) that are often utilized in discourses on Islamic bioethics, namely qasd (intention), yaqin̄ (certainty), darar (injury), darura (necessity), and `urf (custom), would instead reveal some major ethical and moral flaws of this new medical technology in the selection of non-disease-related socially desirable traits, and its non-compliance with the spirit and essence of Islamic law (shariah). Muslim scholars, jurists, doctors, and biomedical scientists should debate this further and issue a fatwa on this new medical technology platform.

Impact of vitamin D in children with chronic tonsillitis (immunohistochemical study of CD68 polarisation and proinflammatory cytokines estimation).

Inflammatory processes are increasingly attributed to macrophage polarization. Proinflammatory macrophages promote T helper (Th) 1 response, tissue repair, and Th2 responses. Detection of macrophages in tissue sections is facilitated by CD68. Our study is focused on the expression of CD68 and the estimation of proinflammatory cytokines in children's patients with chronic tonsillitis secondary to vitamin D supplementation. This hospital-based Randomized prospective case-control study was conducted on 80 children with chronic tonsillitis associated with vitamin D deficiency where (40 received vitamin D 50,000 IU weekly for 3-6 months and 40 received 5 ml distilled water as placebo). The serum 25-hydroxyvitamin D [25(OH)D] was measured using an Enzyme-linked immunosorbent assay on all included children. Different histological and immunohistochemical studies for the detection of CD68 were done. There was a significantly lower serum level of 25(OH)D in the placebo group versus the vitamin D group (P < 0.001). The levels of pro-inflammatory cytokines, TNFα, and IL-2 significantly increased in the placebo group as compared to the vitamin D group (P < 0.001). The increased level of IL-4 and IL-10 in the placebo group as compared to the vitamin D group was insignificant (P = 0.32, 0.82) respectively. Vitamin D supplementation alleviated the deleterious effect of chronic tonsillitis on the histological structure of the tonsil. Tonsillar tissues of the children in the control and vitamin D groups demonstrated a highly statistically significantly lower number of CD68 immunoexpressing cells compared with those in the placebo group (P < 0.001). Low vitamin D may play a role in chronic tonsillitis. Vitamin D supplementation could help reduce the occurrence of chronic tonsillitis in susceptible children.

Impact of Systemic Diseases on Olfactory Function in COVID-19 Infected Patients.

Background: COVID-19 (SARS-CoV-2/2019-nCoV) is now a major public health threat to the world. Olfactory dysfunctions (ODs) are considered potential indicating symptoms and early case identification triaging for coronavirus disease 2019 (COVID-19). The most common reported comorbidities are diabetes mellitus, chronic lung disease, and cardiovascular disease. The objective of this study was to evaluate prevalence of different types of smell disorders in patients with laboratory-confirmed COVID-19 infection and impact of involved systemic diseases. Methodology: A cross-sectional retrospective study has been done for patients with laboratory-confirmed COVID-19 infection (mild-to-moderate). The data collected from patient's files and developed online electronic questionnaire (WhatsApp) based on the patients most common and recurrent reported data including: a) symptoms of olfactory dysfunction and associated covid19 symptoms fever and headache, cough, sore throat, pneumonia, nausea, vomiting and diarrhea, arthralgia and myalgia and taste dysfunction. b) Associated systemic diseases including: diabetes, hypertension, asthma, chronic renal disease, chorionic liver disease and hypothyroidism. Results: Of 308 patients confirmed with Covid-19 infection, (72.4%) developed OD distributed as follows; complete anosmia (57.8%), troposmia (8.4%), hyposmia (2.9%), partial anosmia (2.6%) and euosmia (0.6%). Significantly increased prevalence of diabetes, hypertension asthma in the group with olfactory dysfunction (p < 0.001), chronic liver disease (p = 0.005), and hypothyroidism (p = 0.03). Conclusion: The development of ODs after Covid-19 infection was associated with mild disease form and lower hospitalization. In addition, it showed significant relationship with preexisting systemic diseases. Anosmia is the common modality of ODs.

Comparative analysis of IVF-ICSI outcomes between advanced and early stage of endometriosis stimulated with HMG.

INTRODUCTION: Endometriosis is a challenging disease to treat, and patients may eventually need in vitro fertilisation with Intracytoplasmic sperm injection (IVF/ICSI) to conceive after other modalities failed. There are inconsistent outcomes of IVF performance in patients with endometriosis especially with highly purified human menotropin gonadotrophin (hMG). This study was commenced to determine whether the use of hMG affects the IVF outcome in different stage of endometriosis. MATERIALS AND METHODS: This is an observational study. Eighty-seven women who had endometriosis confirmed surgically and underwent IVF/ICSI treatment, stimulated with hMG alone were included. Based on the revised American Society for Reproductive Medicine (rASRM), the participants were classified as early endometriosis (I/II) (n=39) or advanced endometriosis (III/IV) (n=35). The main outcome measures used were clinical pregnancy rate. RESULTS: Women with advanced endometriosis had a lower oocyte yield, less good quality day-3 embryos and lower clinical pregnancy rate compared with the mild endometriosis. However, higher fertilisation rate were recorded in advanced stage endometriosis compared to milder disease. CONCLUSIONS: The rASRM classification of endometriosis is valuable in predicting IVF outcome as advanced endometriosis performs poorly compared to a milder disease. Highly purified hMG could be an alternative as an ovarian stimulation in endometriosis.

Cell viability and electrical response of breast cancer cell treated in aqueous graphene oxide solution deposition on interdigitated electrode.

Breast cancer is one of the most reported cancers that can lead to death. Despite the advances in diagnosis and treatment procedures, the possibility of cancer recurrences is still high in many cases. With that in consideration, researchers from all over the world are showing interest in the unique features of Graphene oxide (GO), such as its excellent and versatile physicochemical properties, to explore further its potential and benefits towards breast cancer cell treatment. In this study, the cell viability and electrical response of GO, in terms of resistivity and impedance towards the breast cancer cells (MCF7) and normal breast cells (MCF10a), were investigated by varying the pH and concentration of GO. Firstly, the numbers of MCF7 and MCF10a were measured after being treated with GO for 24 and 48 h. Next, the electrical responses of these cells were evaluated by using interdigitated gold electrodes (IDEs) that are connected to an LCR meter. Based on the results obtained, as the pH of GO increased from pH 5 to pH 7, the number of viable MCF7 cells decreased while the number of viable MCF10a slightly increased after the incubation period of 48 h. Similarly, the MCF7 also experienced higher cytotoxicity effects when treated with GO concentrations of more than 25 µg/mL. The findings from the electrical characterization of the cells observed that the number of viable cells has corresponded to the impedance of the cells. The electrical impedance of MCF7 decreased as the number of highly insulating viable cell membranes decreased. But in contrast, the electrical impedance of MCF10a increased as the number of highly insulating viable cell membranes increased. Hence, it can be deduced that the GO with higher pH and concentration influence the MCF7 cancer cell line and MCF10a normal breast cell.

Fertility preservation opportunities for cancer patients in Malaysia.

Fertility preservation is significant for oncology patients to maintain their ability to start a family when they are ready. Onco-fertility, as a discipline, exists at the intersection of oncology and reproductive medicine that safeguards and expands the fertility options for cancer survivors, by facilitating early intervention and suitable treatment with favourable outcomes. Successful fertility preservation requires a comprehensive networking among the gynaecologists, oncologists, pathologists, imaging and other specialists, involved in diagnosing and treating cancer in the reproductive age group. There are several ways in which fertility can be preserved, like role of gonadotrophin releasing hormone analogues, in vitro maturation, and cryopreservation.

Antifungal Compound Isolated from Catharanthus roseus L. (Pink) for Biological Control of Root Rot Rubber Diseases.

Rigidoporus microporus, Ganoderma philippii, and Phellinus noxius are root rot rubber diseases and these fungi should be kept under control with environmentally safe compounds from the plant sources. Thus, an antifungal compound isolated from Catharanthus roseus was screened for its effectiveness in controlling the growth of these fungi. The antifungal compound isolated from C. roseus extract was determined through thin layer chromatography (TLC) and nuclear magnetic resonance (NMR) analysis. Each C. roseus of the DCM extracts was marked as CRD1, CRD2, CRD3, CRD4, CRD5, CRD6, and CRD7, respectively. TLC results showed that all of the C. roseus extracts peaked with red colour at Rf = 0.61 at 366 nm wavelength, except for CRD7. The CRD4 extract was found to be the most effective against R. microporus and G. philippii with inhibition zones of 3.5 and 1.9 mm, respectively, compared to that of other extracts. These extracts, however, were not effective against P. noxius. The CRD4 extract contained ursolic acid that was detected by NMR analysis and the compound could be developed as a biocontrol agent for controlling R. microporus and G. philippii. Moreover, little or no research has been done to study the effectiveness of C. roseus in controlling these fungi.

A survey of doctors' and nurses' knowledge, attitudes and compliance with infection control guidelines in Birmingham teaching hospitals.

This study investigated knowledge about infection control amongst doctors and nurses through a cross-sectional survey conducted between March and May 2001 in three Birmingham, UK teaching hospitals. Seventy-five doctors and 143 nurses, representing 7% and 4%, respectively, of potential respondents, participated in the study measuring knowledge of, attitudes towards, and compliance with universal precautions. Overall knowledge of risks of blood-borne virus (BBV) transmission from an infected patient after needlestick injury was low [44.0% for hepatitis B virus (HBV), 38.1% for hepatitis C virus (HCV), 54.6% for human immunodeficiency virus (HIV)]. There were significant differences between doctors and nurses concerning the estimations of HBV (e-antigen +) (P=0.006) and HIV (P<0.001) transmission risks. Eighty-six percent of nurses stated that they treat each patient as if they are carrying a BBV compared with 41% of doctors. Doctors and nurses differed significantly in their attitudes about and reported compliance with washing hands before and after patient contact and with wearing gloves when taking blood (P<0.001 for all). Doctors consistently de-emphasized the importance of, and reported poor compliance with, these procedures. Doctors were also more likely to state that they re-sheath used needles manually than were nurses (P<0.001). Thirty-seven percent of respondents reported that they had suffered a needlestick injury with a used needle, with doctors more likely to be injured than nurses (P=0.005). Twenty-eight percent of these doctors and 2% of the nurses did not report their needlestick injuries (P=0.004). Education, monitoring, improved availability of resources, and disciplinary measures for poor compliance are necessary to improve infection control in hospitals, especially amongst doctors.

Studies of the p53 gene mutation in Saudi non-Hodgkin's lymphoma.

Tumor biopsies (paraffin embedded tissue) obtained from 45 Saudi patients with non-Hodgkin's lymphoma (NHL) were examined for the incidence of p53 mutations screened by polymerase chain reaction (PCR) and single strand conformation polymorphism (SSCP) analysis. DNA sequencing was carried out to confirm the occurrence of p53 mutation in PCR products showing abnormal migration by SSCP analysis. Only 1/45 samples showed the incidence of a homozygous mutation at codon 179 (exon 5) of the p53 gene that replaces histidine with tyrosine. The data showed that the frequency of p53 mutations was very low in Saudi NHL. Our results are consistent with the general observation that the p53 mutation is rather infrequent in hematopoietic malignancies like NHLs.

The stress-activated protein kinase subfamily of c-Jun kinases.

The mitogen-activated protein (MAP) kinases Erk-1 and Erk-2 are proline-directed kinases that are themselves activated through concomitant phosphorylation of tyrosine and threonine residues. The kinase p54 (M(r) 54,000), which was first isolated from cycloheximide-treated rats, is proline-directed like Erks-1/2, and requires both Tyr and Ser/Thr phosphorylation for activity. p54 is, however, distinct from Erks-1/2 in its substrate specificity, being unable to phosphorylate pp90rsk but more active in phosphorylating the c-Jun transactivation domain. Molecular cloning of p54 reveals a unique subfamily of extracellularly regulated kinases. Although they are 40-45% identical in sequence to Erks-1/2, unlike Erks-1/2 the p54s are only poorly activated in most cells by mitogens or phorbol esters. However, p54s are the principal c-Jun N-terminal kinases activated by cellular stress and tumour necrosis factor (TNF)-alpha, hence they are designated stress-activated protein kinases, or SAPKs. SAPKs are also activated by sphingomyelinase, which elicits a subset of cellular responses to TNF-alpha (ref. 9). SAPKs therefore define a new TNF-alpha and stress-activated signalling pathway, possibly initiated by sphingomyelin-based second messengers, which regulates the activity of c-Jun.

No mutations in the translated region of exon 1 in the TSH receptor in Graves' thyroid glands.

We have amplified a 285 base pair by nested polymerase chain reaction 38 nucleotide downstream from the most 5' transcription initiation site (7) encoding 55 of the 57 residues of exon 1 of the human TSH receptor. These DNA were amplified from 10 tissue blocks of thyroid tissue removed at subtotal thyroidectomy from 10 patients with Graves' disease. The amplified 285 nucleotide fragments were sequenced in search of mutations in the coding region of exon 1 and polymorphism in the 120 nucleotides of the untranslated region upstream of the first ATG codon. No such variations were found. We conclude that the polymorphism or mutation of the part of the TSH receptor extracellular domain encoded by exon 1 and of sequences immediately upstream of the first ATG codon are not relevant to the pathogenesis of Graves' disease.

Regulation of an epitope-tagged recombinant Rsk-1 S6 kinase by phorbol ester and erk/MAP kinase.

Phorbol ester tumor promoters (TPA) activate the endogenous erk/MAP kinases and Rsk S6 kinases but not the p70S6 kinase in COS cells. DNA sequences encoding the rat Rsk-1 S6 kinase (homologous to Xenopus rsk alpha), modified by insertion of a peptide epitope at the polypeptide aminoterminus, were expressed transiently in COS cells. TPA stimulates the 40S and peptide kinase activity of the recombinant epitope-tagged Rsk-1, as well as the extent of Rsk-1 autophosphorylation in vitro (32P-Ser >> 32P-Thr). Indications that the conformation of the recombinant Rsk-1 polypeptide is substantially changed after activation by TPA in situ include a retarded mobility of the Rsk-1 polypeptide on SDS-PAGE and the appearance of new 32P-peptides during autophosphorylation in vitro. All these features of the TPA-activated Rsk-1 S6 kinase are abolished by dephosphorylation of the kinase in vitro with Ser/Thr phosphatase-2A. TPA increases 32P incorporation into recombinant Rsk-1 by 2-3-fold (32P-Ser >> 32P-Thr). Peptide mapping exhibits a single major 32P-peptide in Rsk-1 isolated from unstimulated cells and 10-12 additional 32P peptides after TPA treatment in situ. Phosphorylation of basal or phosphatase-2A-treated recombinant Rsk-1 in vitro with erk2/MAP kinase increases Rsk-1 40S kinase, peptide kinase, and autophosphorylating activity, retards migration of Rsk-1 polypeptides on SDS-PAGE, and generates new sites of Rsk-1 autophosphorylation in vitro. By contrast, TPA-activated Rsk-1 is not altered in these properties by autophosphorylation in vitro. By contrast, TPA-activated Rsk-1 is not altered in these properties by phosphorylation in vitro with erk2/MAP kinase. Activation of Rsk-1 in situ with TPA diminishes by over 90% the extent of Rsk-1 phosphorylation achieved in vitro by erk2/MAP kinase, as compared to the parallel phosphorylation of a phosphatase-2A-treated Rsk-1; basal Rsk-1 is intermediate. Peptide maps of phosphatase-2A-treated Rsk-1 after phosphorylation in vitro with erk2/MAP kinase exhibit 32P-peptides that comigrate with nearly all of the 32P-peptides present in TPA-activated-32P Rsk-1 labeled in situ, plus several 32P-peptides characteristic of Rsk-1 autophosphorylation in vitro.(ABSTRACT TRUNCATED AT 400 WORDS)

Human müllerian inhibiting substance: enhanced purification imparts biochemical stability and restores antiproliferative effects.

Separation of copurifying protease activity from recombinant human Müllerian inhibiting substance (rhMIS) bound to a monoclonal antibody immunoaffinity column by a high-salt wash results in cleaner preparations of rhMIS resistant to cleavage upon storage. In addition, an inhibitor of rhMIS antiproliferative activity is removed. Proteolytic cleavages produced by either a copurifying protease or exogenous plasmin occur at residues 229 and 427 but do not abolish rhMIS biological activity. This report details the modified immunoaffinity column isolation protocol suitable for proteins such as rhMIS and describes the biochemical and antiproliferative properties of this protein.

Molecular structure of a major insulin/mitogen-activated 70-kDa S6 protein kinase.

The molecular structure of a rat hepatoma 70-kDa insulin/mitogen-stimulated S6 protein kinase, obtained by molecular cloning, is compared to that of a rat homolog of the 85-kDa Xenopus S6 protein kinase alpha; both kinases were cloned from H4 hepatoma cDNA libraries. The 70-kDa S6 kinase (calculated molecular mass of 59,186 Da) exhibits a single catalytic domain that is most closely related in amino acid sequence (56% identity) to the amino-terminal, kinase C-like domain of the rat p85 S6 kinase (calculated molecular mass of 82,695 Da); strong similarity extends through a further 67 residues carboxyl-terminal to the catalytic domain (40% identity), corresponding to a region also conserved among the kinase C family. Outside of this segment of approximately 330 amino acids, the structures of the p70 and p85 S6 kinases diverge substantially. The p70 S6 kinase is known to be activated through serine/threonine phosphorylation by unidentified insulin/mitogen-activated protein kinases. A model for the regulation of p70 S6 protein kinase activity is proposed wherein the low activity of the unphosphorylated enzyme results from the binding of a basic, inhibitory pseudosubstrate site (located carboxyl-terminal to the extended catalytic domain) to an acidic substrate binding region (located amino-terminal to the catalytic domain); substrate binding is thereby prevented. S6 kinase activation requires displacement of this inhibitory segment, which is proposed to occur consequent to its multiple phosphorylation. The putative autoinhibitory segment contains several serine and threonine residues, each followed directly by a proline residue. This motif may prevent autophosphorylation but permit transphosphorylation; two of these serine residues reside in a maturation promoting factor (MPF)/cdc-2 consensus motif. Thus, hormonal regulation of S6 kinase may involve the action of MPF/cdc-2 or protein kinases with related substrate specificity.

Wegener's granulomatosis autoantigen is a novel neutrophil serine proteinase.

Circulating IgG autoantibodies that produce cytoplasmic immunofluorescence staining of ethanol-fixed normal neutrophils have recently been found in a large percentage of patients with active Wegener's granulomatosis. Such autoantibodies are rarely found in other diseases and are therefore virtually diagnostic of Wegener's granulomatosis. The nature of the neutrophil antigen defined by these autoantibodies is controversial and the roles of the antigen and/or autoantibodies in the pathogenesis of Wegener's granulomatosis are unknown. We studied serum samples that produce the cytoplasmic pattern of staining from 10 patients with a diagnosis of Wegener's granulomatosis. By Western blot analysis, all 10 sera reacted with a 29-Kd neutrophil protein (p29). We generated a mouse monoclonal antibody directed against this antigen. The monoclonal antibody produced the same immunofluorescence staining pattern as the serum autoantibodies and was used to affinity-purify p29. The purified antigen had a novel N-terminal sequence homologous to members of the serine proteinase family and bound to radiolabeled diisopropyl fluorophosphate (DFP). We conclude that the neutrophil antigen responsible for the cytoplasmic staining pattern produced by autoantibodies in patients with active Wegener's granulomatosis is a distinctive serine proteinase.

Protein synthesis in yeast Saccharomyces cerevisiae. Purification of Co-eIF-2A and 'mRNA-binding factor(s)' and studies of their roles in Met-tRNAf.40S.mRNA complex formation.

Antibodies prepared against a homogeneous preparation of Co-eIF-2A20 [Ahmad et al. (1985) J. Biol. Chem. 260, 6955-6959] reacted with several polypeptides including an 80-kDa polypeptide present in a crude yeast ribosomal salt wash. This 80-kDa polypeptide, containing Co-eIF-2A (Co-eIF-2A80) activity, has been extensively purified using a two-step purification procedure involving an immunoaffinity column chromatograph prepared using antibodies against Co-eIF-2A20 (fraction II) and hydroxyapatite chromatography (fraction III). The factors, eIF-2 + homogeneous Co-eIF-2A80 (fraction III) promoted Met-tRNAf.40S complex formation with an AUG codon but not with a physiological mRNA or a polyribonucleotide messenger poly(U,G) whereas eIF-2 + a partially purified Co-eIF-2A80 preparation (fraction II) promoted Met-tRNAf.40S complex formation with an AUG codon as well as with globin mRNA and poly(U,G) messenger. This factor-promoted Met-tRNAf binding to 40S ribosomes depends absolutely on the presence of a polyribonucleotide messenger containing an initiation codon (such as AUG or GUG). Other polyribonucleotide messengers tested, such as poly(U), poly(A) and poly(A,C) were completely ineffective in this binding reaction. This result indicates that the Met-tRNAf.40S.mRNA complex is formed by a direct interaction between Met-tRNAf, 40S ribosomes and the initiation site in mRNA. A mechanism has been proposed for Met-tRNAf.40S.mRNA complex formation in yeast.

Protein synthesis in rabbit reticulocytes. A study of the roles of Co-eIF-2, Co-eIF-2A80, and GDP in peptide chain initiation.

The roles of Co-eIF-2, Co-eIF-2A80, and GDP in ternary complex and Met-tRNAf X 40 S initiation complex formation were studied. 1) Partially purified eukaryotic initiation factor 2 (eIF-2) (50% pure) preparations contained 0.4-0.6 pmol of bound GDP/pmol of eIF-2. eIF-2 purity was calculated from ternary complex formation in the absence of Mg2+ and in the presence of excess Co-eIF-2. 2) In the absence of Mg2+, approximately 30% of the potentially active eIF-2 molecules formed ternary complexes, and both Co-eIF-2 and Co-eIF-2A80 were equally effective in full activation of the eIF-2 molecules for ternary complex formation. 3) In the presence of Mg2+, approximately 10% of the potentially active eIF-2 molecules formed ternary complexes in the absence of ancillary factors, and the ancillary factors Co-eIF-2A80 and Co-eIF-2 raised the incorporation to 20 and 50% of the eIF-2 molecules, respectively. 4) In the absence of Mg2+, [3H]GDP in preformed eIF-2 X [3H]GDP was readily displaced by GTP during ternary complex formation. 5) In the presence of Mg2+, [3H]GDP remained tightly bound to eIF-2 and ternary complex formation was inhibited. Co-eIF-2, but not Co-eIF-2A80, was effective in promoting [3H]GDP displacement and the former was more effective in promoting ternary complex formation than the latter. 6) eIF-2 X [3H]GDP was converted to eIF-2 X [3H] GTP by incubation in the presence of nucleoside-5'-diphosphate kinase and ATP, but the eIF-2 X [3H]GTP thus formed did not bind Met-tRNAf in the presence of Mg2+ and required exogeneous addition of Co-eIF-2 and GTP for ternary complex formation and GTP displacement. 7) In the absence of Mg2+, the increased ternary complex formed in the presence of eIF-2 X [3H] GDP and Co-eIF-2A80 (with accompanying loss of [3H] GDP) was inactive in a subsequent reaction, which involves Met-tRNAf transfer to 40 S ribosomes (in the presence of Mg2+), and required trace amounts of Co-eIF-2 for such activity. Based on the above observations, we have suggested a two-step activation of eIF-2 molecules by the Co-eIF-2 protein complex for functional ternary complex formation. One of these steps involves the Co-eIF-2A component of Co-eIF-2. This activation results in stimulated Met-tRNAf binding to eIF-2 and is most apparent in the absence of Mg2+ and with aged eIF-2 molecules.(ABSTRACT TRUNCATED AT 400 WORDS)