Biowaxes from Palm Oil as Promising Candidates for Cosmetic Matrices and Pharmaceuticals for Human Use

The production of waxes from vegetable oils, such as palm oil, for use as a base material in products for human applications is an alternative to those derived from petroleum and animals. Seven palm oil-derived waxes, called biowaxes (BW1-BW7) in this work, were obtained by catalytic hydrotreating of refined and bleached African palm oil and refined palm kernel oil. They were characterized by three properties: compositional, physicochemical (melting point, penetration value, and pH), and biological (sterility, cytotoxicity, phototoxicity, antioxidant, and irritant). Their morphologies and chemical structures were studied by SEM, FTIR, UV-Vis, and ¹H NMR. The BWs presented structures and compositions similar to natural biowaxes (beeswax and carnauba). They had a high concentration of waxy esters (17%-36%) with long alkyl chains (C, 19-26) per carbonyl group, which are related to high melting points (<20-47.9 °C) and low penetration values (2.1-3.8 mm). They also proved to be sterile materials with no cytotoxic, phototoxic, antioxidant, or irritant activity. The biowaxes studied could be used in cosmetic and pharmacological products for human use.

Clinical presentation of acute coronary syndrome in HIV infected adults: a retrospective analysis of a prospectively collected cohort

OBJECTIVES

To compare clinical presentation and short-term prognosis of acute coronary syndrome (ACS) in HIV-infected and uninfected adults.

DESIGN

Retrospective analysis of a prospectively collected cohort.

METHODS

HIV-infected patients with myocardial infarction or unstable angina were identified by clinical history and specific characteristics of HIV infection were consecutively registered. Surviving patients were followed for at least one month after discharge. Risk factors for cardiovascular disease, clinical symptoms at admission, type of ACS, delivery of care, and factors associated with prognosis were compared between HIV-infected and uninfected adults.

RESULTS

Among 627 patients included, 44 (7%) were HIV-infected patients. HIV-infected patients were younger, more frequently men, and had higher prevalence of cardiovascular risk factors than uninfected patients. HIV-infected patients persisted frequently with less pain at Emergency Department (ED) (34% vs 82%, P<0.001) and complained of dyspnea (2% vs 15%, P<0.05) persisted in respect to HIV-uninfected patients. ST-elevation myocardial infarction was the most frequent ACS in HIV-infected patients (59% vs 24%) whereas non-ST-elevation myocardial infarction (23% vs 38%) and unstable angina (18% vs 38%) were the predominant ones in uninfected patients (P<0.001). Catheterism was performed more commonly in HIV-infected patients (75% vs 62%, P<0.01) and similarly admitted in the coronary care unit (38% vs 41%, P=0.81). The evolution was similar in both groups. When HIV-infected patients were matched by age and sex with a subgroup of 88 HIV-uninfected patients, most of the differences disappeared.

CONCLUSIONS

HIV-infected adults presenting with ACS are younger and have fewer symptoms than uninfected. Despite having a more established disease, short-term prognosis is similar.

[Consequences of heroin consumption: compartmental syndrome and rhabdomyolysis]

Compartment syndrome is a condition in which increased pressure within a limited space compromises tissue perfusion with the development of rhabdomyolysis. The causes can be physical, such as the pressure exerted on an anatomical region, or it can be associated with the consumption of illegal drugs, especially heroin. In this latter case, toxic and immunological mechanisms are involved in the physiopathology. Acute renal failure develops in 30% of cases of rhabdomyolysis. Its treatment includes efficient volume replacement, forcing urinary alkalinization and the administering of furosemide and mannitol, with certain precautions. No benefit has been shown in dopamine. When a heroin addict patient shows a clinical pattern of tumescence of his extremities, with or without a period of unconsciousness, the presence of compartment syndrome is to be suspected.

[Treatment of pain in the oncology patient]

Pain is a symptom with a high prevalence in patients with cancer and causes an important deterioration in their quality of life. With the measures laid out by the WHO in 1986, which divides the different therapeutic options available in three ascending steps, pain can be controlled in a high percentage of cases. Those patients who are difficult to control with these measures can benefit from the application of neuromodulation techniques by experts in the treatment of chronic pain. The correct employment of the different medicines (non-steroidal anti-inflammatory medicines, opiates and coadjuvants), knowledge of the secondary effects, loss of fear in the face of opiates and knowledge of the different algic syndromes associated with the oncology patient, must be accompanied by a suitable evaluation of the pain according to the different scales, both in the phase of the treatment's initiation and in the follow-up of the patient.

The global regulators GacA and sigma(S) form part of a cascade that controls alginate production in Azotobacter vinelandii

Transcription of the Azotobacter vinelandii algD gene, which encodes GDP-mannose dehydrogenase (the rate-limiting enzyme of alginate synthesis), starts from three sites: p1, p2, and p3. The sensor kinase GacS, a member of the two-component regulatory system, is required for transcription of algD from its three sites during the stationary phase. Here we show that algD is expressed constitutively throughout the growth cycle from the p2 and p3 sites and that transcription from p1 started at the transition between the exponential growth phase and stationary phase. We constructed A. vinelandii strains that carried mutations in gacA encoding the cognate response regulator of GacS and in rpoS coding for the stationary-phase sigma(S) factor. The gacA mutation impaired alginate production and transcription of algD from its three promoters. Transcription of rpoS was also abolished by the gacA mutation. The rpoS mutation impaired transcription of algD from the p1 promoter and increased it from the p2 sigma(E) promoter. The results of this study provide evidence for the predominant role of GacA in a regulatory cascade controlling alginate production and gene expression during the stationary phase in A. vinelandii.

[Vascular hereditary dementia CADASIL type in Colombia. III. Linkage analysis to notch3 gene]

OBJECTIVE

To perform linkage analysis between the Short Tandem Repeats (STR) microsatellite markers D19S923, D19S929, D19S22, which are in strong genetic linkage to Notch3 gene in order to contrast the hypothesis that the vascular hereditary dementia phenotype described in a multigenerational extended pedigree from Colombia correspond to CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy). Even we know that using techniques as the Single Strand Conformational Polymorphisms (SSCP) could determine mutations in Notch3, the rationality of this approach is that intronic variations could not be defined and that we are interested in determine if some forms of the clinical presentation and its phenotypic variability make part of CADASIL.

INTRODUCTION

The CADASIL phenotype is caused by mutations in the Notch3 gene. Clinical features of CADASIL are: 1. Recurrent cerebra-vascular episodes; 2. Migraine history; 3. History of transitory ischemic attack and, 4. Behavior changes and dementia.

MATERIAL AND METHODS

By using SIMLINK we showed that the extended genealogy had the enough power to detect significant LOD (logarithm of oods) score values when Notch3 was considered the disorder cause. Linkage analysis was carried out by using parametric and non parametrical methods. The Elston-Stewart general method was used as the parametrical analysis and the sib pair method as the non-parametrical one. We perform simulations changing the affection status codification by including as affected or not including those individuals with migraine. Furthermore, in order to detect the stability of the results, we changed the penetrance values, the genetic frequencies on both, the marker loci and the affection locus.

RESULTS

The maximum pair-wise LOD score was 2.04 which was detected at the marker D19S23 with q= 0.11cM. This distance correspond exactly with the Notch3 location. That is 100 times more probable that there is linkage that there is not. In other words this probability could be explained as if the phenotype correspond to CADASIL than to other vascular dementia. The non parametric results were compatibles with the parametric ones. When the migraine symptom was considered as a part of the affected status, the LOD score values showed not linkage.

CONCLUSIONS

The results of the linkage analysis to these STR microsatellite markers suggest that the vascular hereditary dementia phenotype described in this family correspond to CADASIL caused by a polymorphism on the Notch3 gene. On the contrary, these same results suggest that the migraine phenotype is not a part of the progressive dementia.

[Diagnosis of mesial temporal sclerosis with magnetic resonance imaging]

INTRODUCTION

Mesial temporal sclerosis (MTS) is a progressive drug-resistant epileptic syndrome which requires rapid, effective diagnosis and treatment. Histologically there is atrophy and gliosis of the hippocampus.

OBJECTIVE

To establish magnetic resonance (MR) imaging guidelines for correct diagnosis.

PATIENTS AND METHODS

We made a prospective study of 78 patients with drug-resistant temporal lobe epilepsy (44 women and 34 men; age 6-66 years, mean 31 years). Using a magnet of 1.5 Teslas paracoronal sections were made of the hippocampus with T1 volumetric with inversion-recovery, FLAIR (fluid-attenuated inversion-recovery) and T2 relaxometry. A control group of 30 healthy volunteers was established. The reduction in volume and hippocampal T2 hyperintensity were considered to be MTS diagnosed on MR.

RESULTS

No hippocampal differences were observed among the healthy volunteers. The confidence intervals (mean +/- 1.96 SD) were: right volume: 4.169-5.911 mm3; left volume: 4.097-5.940 mm3; time of T2 relaxation: 98-113 ms. MTS was observed in 42 patients (54%): 24 left, 14 right and four asymmetrical bilateral. The results of the diagnostic validity (sensitivity/specificity) were: T1 volumetric 91/92%, FLAIR 93.5/98% and T2 relaxometry 91/92%. There was atrophy of other extrahippocampal structures in five cases of MTS; 10 patients with MTS (23.5%) had another extrahippocampal lesion associated (dual pathology), particularly migration disorders; 21 patients (27%) had lesions without MTS (tumors, alterations of migration, nonspecific gliosis) and in 15 cases (19%) there were no abnormal findings. A total of 27 patients were operated on: 22 with MTS (21 had diagnostic MR, one case had no abnormal findings), four cases had tumors and one had cortical dysplasia.

CONCLUSION

The combination of quantitative techniques (T1 volumetric with inversion-recovery and T2 relaxometry) and FLAIR optimize MTS diagnosis using MR.

The GacS sensor kinase regulates alginate and poly-beta-hydroxybutyrate production in Azotobacter vinelandii

Azotobacter vinelandii produces two polymers: the extracellular polysaccharide alginate and the intracellular polyester poly-beta-hydroxybutyrate (PHB). A cosmid clone (pSMU588) from an A. vinelandii gene library diminished alginate production by A. vinelandii mucoid strain ATCC 9046. The nucleotide sequence and predicted amino acid sequence of the locus responsible for the mucoidy suppression revealed 65% identity to Pseudomonas GacS, a transmembrane sensor kinase of the two-component regulators, whose cognate response regulator, GacA, is a global activator regulating several products and virulence factors. Plasmid pMC15, harboring gacS, and a strain carrying a gacS nonpolar mutation were constructed. Either pMC15 or the gacS mutation significantly reduced alginate production and transcription of algD, the gene coding for the key enzyme GDP-mannose dehydrogenase of the alginate biosynthetic pathway. We found that the gacS mutation also reduced PHB accumulation and impaired encystment. Taken together, these data indicate that in A. vinelandii the gacSA global system regulates polymer synthesis.

False positive thallium-201 SPECT imaging in brain abscess

Three cases of intracranial 201Tl uptake, reported as positive tumour activity in patients with a final diagnosis of abscess, are described. 201Tl has been proposed as a useful oncotropic radiotracer in the diagnosis of brain tumour activity. These cases suggest a note of caution in the interpretation of 201Tl brain images in the differential diagnosis of an intracranial expanding mass.

[Iron, zinc and copper content of foods commonly consumed in Mexico]

Nutrient composition in foods is necessary for the determination of nutrient intake. Food composition tables used for dietary studies in Mexico do not have information of zinc, iron and copper; when present the values have been extrapolated from laboratory analysis carried out with foods in other countries and regions of the world. In this study zinc, iron, and copper content of 104 plant foods and 32 animal foods was determined. The procedure used was atomic absorption spectrophotometry for the minerals. Foods were grouped into cereals, vegetables, fruits, legumes and animal foods. Zinc content ranged from 0.018 mg/100 g for strawberry to 9.193 mg/100 g for beef. Iron content ranged from 0.113 mg/100 g for yogurt to 19.82 mg/100 g for a commercial cereal which had minerals added during processing. In some foods copper was not found and the highest content was 3.371 mg/100 g in beef liver. This study has provided information on zinc, iron and copper content of the most commonly consumed foods in Mexico.

[Spontaneous epidural spinal hematoma: report of 2 cases and review of the literature]

Spontaneous spinal epidural hematoma is an uncommon cause of cord compression. This lesion has been correlated with some precipitant factors, but frequently is idiopathic. It's a unusual process, more uncommon in children, and there are only 350 cases reported in the literature. Etiology is unknown and there are several theories about it. The clinical presentation is remarkably uniform, with local back and radicular pain followed by sensory and motor disfunction. Early diagnosis and treatment are very important for the functional recovery of the patient. In this article, the literature is reviewed, especially the etiological and therapeutic aspects, and two new cases are reported. These cases can help to define the etiology of this entity.

Cognitive brain activity in Alzheimer's disease: electrophysiological response during picture semantic categorization

Semantic memory deterioration is a major component of the cognitive decline seen in patients with dementia of the Alzheimer's type (DAT); however, the exact nature of this deficit remains unclear. Some research data support a procedural deficit where there is an inability to access or retrieve the contents of semantic memory, while other data point to a degraded semantic store where the actual content of semantic memory is degraded. Additional information about semantic processing in DAT can be obtained through the use of an event-related potential (ERP) component known as N400. In the present study, ERPs were recorded from 10 young control participants, 10 elderly control participants, and 10 DAT patients in a picture-semantic matching task. Stimuli were presented sequentially as prime-target pairs, with one-half of the targets matching the primes via semantic relationships (e.g., piano-violin) and the other half mismatching the prime (e.g., helmet-violin). The task was to discriminate between semantically related and unrelated pairs of pictures. In the young and elderly control groups, ERPs generated a larger N400 for unrelated than related target pictures, with a maximum amplitude around 380 ms in the young group and around 480 ms in the elderly group. The amplitude of the N400 was significantly reduced in the DAT patients. However, a separate analysis of congruent and incongruent ERPs trials revealed significant differences only with the incongruent trials. The amplitude of incongruent recordings was larger for the elderly control group than for the DAT patients, while the amplitude for congruent recordings was similar in both groups. These findings are consistent with the neuropathological evidence that Alzheimer's disease is a neocortical disconnection syndrome in which there is a loss of structural and functional integrity of long corticocortical tracts. The semantic activation created by the context is not used efficiently in processing stimuli, which affects access to specific concepts and gradually leads to a breakdown in the structure and organization of semantic memory.

ERP assessment of semantic memory in Alzheimer's disease

This study used the technique of Event-Related Potentials (ERPs), specifically the component N400, to evaluate semantic functions in Alzheimer's disease (AD). ERPs of 10 patients with probable AD and 10 asymptomatic elderly control subjects were recorded during a semantic categorization task using pictures as stimuli, 50% of the stimuli were congruent and the other 50% were incongruent. Significant differences for the incongruent ERPs, with a diminished N400 component, was observed in the patients group whereas the amplitude of the congruent ERPs was similar in both groups. The characteristics of the N400 in the patients with probable AD suggest that there is a lack of efficiency in accessing information and shows that there are deficient associative connections within the semantic network.

Randomized single-blind trial of topical ketanserin for healing acceleration of diabetic foot ulcers

The objective of this study was to determine the efficacy of topically applied ketanserin for healing acceleration of diabetic foot ulcers. From August 1993 to September 1994, 140 NIDDM patients entered a randomized single-blind trial of topical ketanserin (Sufrexal, Janssen Pharmaceuticals; n = 69) vs. normal saline (labeled here as placebo; n = 71). All patients were subjected to surgical debridement of necrotic tissue and lavage with normal saline. Wounds were < 100 cm2 in area. Persons with NIDDM and foot ulcers Wagner 2 and 3 with a median of 8 (interquartile range 4-26) weeks duration were included. Ulcer area was measured at 0, 4, 8 and 12 weeks. The groups were similar in age, sex, years of diabetes duration, obesity, ulcer Wagner type, number of previous amputations and surgical debridements during this hospital stay. Average percent reduction in ulcer area at 12 weeks was 87% for ketanserin vs. 63% for placebo (p < 0.001). The regression equations for the least-squares fit to the area (y) against time (x) data points were y = 43.46-3.181x (r = -0.995) for ketanserin and y = 39.46-2.016x (r = -0.999) for placebo (p < 0.01). The 95% confidence limits for slopes were -3.181 +/- 0.98 and -2.016 +/- 0.15. Thus, average daily reduction in ulcer area was 4.5 mm2/day for ketanserin vs. 2.88 mm2/day for placebo. In conclusion, topical ketanserin significantly accelerated wound healing in diabetic neurotrophic foot ulcers when applied as part of a comprehensive healing program.

Head-injured patients who talk and deteriorate into coma. Analysis of 211 cases studied with computerized tomography

Of 838 patients with severe head injuries admitted since the introduction of computerized tomography, 211 (25.1%) talked at some time between trauma and subsequent deterioration into coma. Of these 211 patients, 89 (42.2%) had brain contusion/hematoma, 46 (21.8%) an epidural hematoma, 35 (16.6%) a subdural hematoma, and 41 (19.4%) did not show focal mass lesions. Thus, four of every five patients who deteriorated into coma after suffering an apparently nonsevere head injury had a mass lesion potentially requiring surgery: the mass was intracerebral in 52.3% of the cases and extracerebral in 47.6%. Patients aged 20 years or less had a 39% chance of having a nonfocal mass lesion (diffuse brain damage), a 29% chance of having an epidural hematoma, and a 32% chance of having an intradural mass lesion; patients over 40 years had only a 3% chance of having a nonfocal mass lesion, an 18% chance of having an epidural hematoma, and a 79% chance of having a intradural mass lesion. Sixty-eight (32.2%) patients died and 143 (67.8%) survived. The following were independent outcome predictors (in order of significance): Glasgow Coma Scale score following deterioration into coma, the highest intracranial pressure during the patient's course, the degree of midline shift, the type of intracranial lesion, and the age of the patient. In contrast, the mechanism of injury, the verbal Glasgow Coma Scale score during the lucid interval, and the length of time until deterioration or until operative intervention did not influence the final result.

Trypanosoma (Schizotrypanum) cruzi: repetitive DNA sequence evolution in three geographically distinct isolates

1. Middle-repetitive DNA sequences were analyzed by molecular hybridization to determine both the extent of complementarity and time of evolutionary divergence between isolates of Trypanosoma cruzi from Argentina, Mexico, or Venezuela. 2. Although molecular hybridizations showed no significant difference between the middle-repetitive DNAs of the Mexican and Venezuelan isolates, there was a 2.7% base pair mismatch in hybrid molecules formed by association of strands from both the Mexican and Argentine isolates. 3. Using the rates for divergence of middle-repetitive DNA in sea urchins, the Mexican and Argentine isolates were estimated to have diverged approximately 20-25 million years ago. 4. Analysis of the kinetics for the DNA hybridizations indicates that only minor amplifications of specific gene sequences or changes in the complexity of the genomes could have occurred during the divergence of the three isolates studied.

Subarachnoid haemorrhage of unknown aetiology

The authors review the literature on subarachnoid haemorrhage of unknown aetiology (SAHUE) and analyze a personal series of 212 patients diagnosed as SAHUE. These patients represent 30% of all cases of primary SAH admitted over a 14.5 year period. The age, sex, antecedents and initial clinical presentation of patients with SAHUE were indistinguishable from those of patients with subarachnoid haemorrhage due to ruptured aneurysm (SAHRA). However, the present series of SAHUE compare favourably with both a personal and a previously reported series of SAHRA insofar as clinical grade on admission (94% of patients in grades I-II of Botterell), presence of blood on CT (51%), vasospasm (5%), ischaemic deficits (3.3%), persistent hydrocephalus (3.5%), rebleeding (6%) and fatal result (3.9%) are concerned. The amount of blood on CT scan in our patients with SAHUE was associated with a significantly higher incidence of brain ischaemia and hydrocephalus but did not correlate with the Botterell grade on admission or final outcome, which were good in the majority of cases regardless of the presence or not of visible cisternal haemorrhage. The results of the present series confirm that the final prognosis of patients with primary SAH showing normal four-vessel cerebral angiography is essentially favourable.

Molecular cloning and partial characterization of ribosomal RNA genes from Trypanosoma cruzi

To further analyze the organization of the nuclear rDNA locus in Trypanosoma cruzi, genomic recombinant plasmid clones were constructed and isolated after hybridization with rRNA molecules as hybridization probes. Approximately 11 kilobase pairs from the cistron were cloned in three recombinant plasmids carrying adjacent genomic fragments. Restriction mapping and Southern hybridization experiments performed on these clones indicate the following relative arrangement of the mature rRNA coding sequences: 18S (2.46 kb), S3 (197 b), 24S alpha (2.02 kb), S1 (261 b), 24 beta (1.66 kb), S2 (217 b) and S6 (90 b). Neither S4 (141 b) nor S5 (110 b) sequences were found within these genomic clones. Nevertheless genomic Southerns suggest a linkage of S4 towards the 3' end of this genetic system.

Genomic DNA sequence polymorphism of Trypanosoma (Schizotrypanum) cruzi isolates with phenotypic variation

1. Single-copy DNA sequences were analyzed by molecular hybridization to determine both the extent of complementarity and time of evolutionary divergence between three isolates obtained from Argentina, Mexico or Venezuela. 2. The Mexico-Venezuela pair appeared much closer than the Mexico-Argentina pair. 3. The tentative values for time of evolutionary divergence were higher than those estimated previously by allozymic variation.

Stagewise decline in the activity of brain protein synthesis factors and relationship between this decline and longevity in two rodent species

The activities of brain initiation factor 2 and brain elongation factor 1, which function as rate-limiting in total protein synthesis, and estimations of brain weight were followed during postnatal life in the rat and the mouse. Both activities decreased in parallel while cumulative brain weight increased. Three exponential components were required for the mathematical expression of each of the three processes in semilogarithmic plots against time. The acceleration curves for the activities and tissue weight demonstrated a mirror image symmetry. Within the general pattern of diminution with age, the negative acceleration of the activities and the positive acceleration of the brain weight displayed repeated bursts. The activities of both factors could also be arranged into several regression lines in log/log plots against time. Significantly, in these plots, the regression line calculated for the whole set of data for each factor activity showed that the value of the ratio of the slopes (mouse to rat) was inversely related to the square root of the ratio of species longevity and was in agreement with the power law relating life spans of cells to species longevity (Röhme, Proc. Natl. Acad. Sci. U.S.A., 78 (1981) 5009).

Heterogeneity of protein-synthesis initiation factors in developing and aging rat brain

Protein synthesis initiation factors from rat brain were assayed in vitro through the formation of the initiator Met-tRNA X initiation factor 2 X GTP ternary complex. The initiation factor showed different intrinsic activity with increase in age. This difference was elicited by additions of high-salt ribosomal-wash protein to incubation mixtures that were already saturated with protein preparations from brains of older animals. This qualitative difference was further documented by examining the sensitivity of the activities of the initiation factor to spermidine and to temperature. The sensitivity to these effectors varied with age. By fitting an exponential decay model to data from the temperature experiments, it was possible to demonstrate that the preparations of the initiation factor from older brains behaved as a multicomponent system. The brain preparations from older animals contained at least two subpopulations of initiation factor. The fractions of these two gross subclasses varied, inversely one to the other, with age.

Small-size ribosomal RNA species in Trypanosoma cruzi

Trypanosoma cruzi ribosomal RNA was analyzed electrophoresis. On agarose gels, where both large- and small-size species are grossly fractionable, it revealed two bands in the small-size region. These were similar in size to the mammalian 5.8 S and 5 S species. Increased resolution, however, showed these two bands to be composite. The pseudo 5.8 S band contained three, and the pseudo 5 S two, discretely sized molecules. The ribosomal binding of four of these five novel species is apparently dependent on large ribosomal subunit proteins. One species is hydrogen bonded to the beta species of 24 S ribosomal RNA. The five species were estimated to be 261, 217, 197, 141 and 110 nucleotides long.

An endonuclease restriction analysis of the ribosomal RNA genes of Trypanosoma cruzi

The location of ribosomal RNA genes in total-nuclear-enriched DNA preparations of Trypanosoma cruzi was analyzed by using restriction endonucleases and the eight cytoplasmic ribosomal RNA species of this organism. Two contiguous SstI DNA fragments of about 9.88 and 1.7 kilobase pairs contained the three large-size ribosomal RNA species, 18 S, beta, and alpha, and three small-size ribosomal RNA species, s1, s2 and s3. The other two small-size ribosomal species, s4 and s5, were located outside the ribosomal RNA cistron and independently of each other. Spacers of a presumed large length, about 20 kilobase pairs or more, hampered the identification of putative adjacent ribosomal RNA cistrons.

Age-dependent decrease in the activity of protein-synthesis initiation factors in rat brain

The age-dependent reduction of brain protein synthesis was examined at the initiation step of translation in the rat. Activity of brain initiation factor 2, as well as that of other eukaryotic initiation factors that contribute to the binding of initiator aminoacyl-tRNA to ribosomes, was found to decrease with age and to decline parallel to the decrease in total protein synthesis and brain elongation factor 1 activity. Change in the activity of initiation factors was demonstrated by the results of two different assays which compared favorably with each other. Decreased activity of preparations of initiation factors derived from older animals was observed in: (1) saturating conditions; (2) mixtures of preparations from different ages; and (3) both major cell fractions, i.e. cell sap and microsomes.

Genome organization and ploidy number in Trypanosoma cruzi

Trypanosoma cruzi total DNA was analyzed by DNA:DNA reassociation kinetics. The nonlinear least-squares computer solution could reasonably be fitted to three second-order kinetic components. The highly repetitive, middle repetitive, and single copy components comprised 9, 35 and 49% of the genome, respectively. The single copy sequences showed a kinetic complexity of approximately 4 times that of Escherichia coli and of some 11,000 average-sized structural genes. The repetitive sequences (about 6900) presented the long-period pattern of interspersion with a modal length of 7800 bases. The kinetic complexity of total DNA was compatible with a value of at least a diploid genome per cell.

Role of elongation factor 1 in the translational control of rodent brain protein synthesis

The translational control of protein synthesis during early postnatal neural development and aging was examined in the mouse and the rat. The activity of brain elongation factor 1 (bEF-1) was found to decrease exponentially with age and to decline parallel to the age-dependent decrease in total protein synthesis in both rodents. This decrement in bEF-1 activity fell within the range of reported age-related decreases in protein synthesis in in vitro systems. The factor was present in multiple forms; the lighter species predominated in older animals, whereas the young light form apparently disappeared with increasing age, and was replaced by other arising from the heavy form. Elongation factor 1 derived from young brains functioned as a rate-limiting component in polypeptide synthesis in previously saturated adult systems. The data suggest that bEF-1 has an important modulatory effect on total brain protein synthesis.

Trypanosoma cruzi ribosomal RNA: internal break in the large-molecular-mass species and number of genes

The large-molecular-mass ribosomal ribonucleic acid from Trypanosoma cruzi probably contains an internal break. The molecule can be obtained in its intact form or in its two fragments depending on the denaturing agents used for its purification and/or display. This break appears to be an in vivo late processing step rather than a random nucleolytic cleavage during in vitro manipulations. Calculations of mass, from gel electrophoretograms, for the large and small main ribosomal ribonucleic acid species and for the two chains derived from the large species gave values of 1.37, 0.84, 0.70 and 0.57 X 10(6) daltons, respectively. Sedimentation velocity measurements in sucrose gradients and in the analytical ultracentrifuge indicated sedimentation coefficients of 24 and 18 S for the large and small main species, respectively. Saturation hybridization curves showed that the nuclear genome, quantified by chemical analysis, contains about 114 ribosomal ribonucleic acid gene copies.

Subunit structure of Trypanosoma cruzi chromatin

Chromatin of Trypanosoma cruzi epimastigotes was found to be arranged in a subunit structure by the demonstration of (i) nu-bodies, (ii) monomeric and oligomeric DNA fragments, and (iii) four basic nuclear proteins which presumably correspond to the intrinsic protein component of nucleosomes. A discrete core fragment of 140 base pairs and a basic nuclear protein fraction clearly similar to most histones H1 were not detected. In contrast with vertebrate material, the nuclear preparations were physically and enzymatically fragile, the basic proteins showed different mobilities in electrophoresis, but the DNA repeat length was similar. The data are discussed in relation to histone regional charge, histone content, and chromatin condensation.