[Changes in nutritional state, metabolic control and treatment of type 1 diabetes in the last 20 years]

OBJECTIVE

The aim of this study is to describe changes in anthropometric characteristics, metabolic control, treatment and prevalence of overweight in diabetic children (DM1) from 2007 compared with another similar group from 1986.

PATIENTS AND METHODS

Observational retrospective study of two groups of diabetic children (n=90). The collection of variables has been made at two cross-sections, 1986 and 2007. The studied variables were: age, years of DM1, sex, weight, height, BMI (and their Z values), HbA(1c) and treatment with insulin (type, number of doses, IU/day and IU/kg/day).

RESULTS

In 2007 group there is a significant increase in Z-weight and Z-BMI (P=.001) when compared with the 1986 group. There was a negative relationship between the years with DM1 and Z-height (P=.05) in the 1986 group. The value of HbA(1c) was lower in the 2007 group (P=.001), but the dose of insulin (IU/day and IU/kg/day) was similar in both groups. The number of daily doses of insulin was higher in the 2007 group (P<.001), the use of insulin analogues dominated overall. A statistically significant relationship between HbA(1c) and treatment with insulin (dose injections, insulin type) was not found. The prevalence of overweight (14.6% vs 2.4%) was significantly higher in the 2007 Group (P=.001).

CONCLUSIONS

The metabolic control (HbA(1c)) had improved and the use of multiple daily doses of insulin has been become the standard, but the prevalence of overweight has increased. We must monitor the emergence of insulin resistance and cardiovascular risk factors in this sensitive population to prevent early cardiovascular disease.

Validity, reliability, and responsiveness of a new short Visual Simplified Respiratory Questionnaire (VSRQ) for health-related quality of life assessment in chronic obstructive pulmonary disease

The Visual Simplified Respiratory Questionnaire (VSRQ) was designed to assess health-related quality of life (HRQoL) in patients with chronic obstructive pulmonary disease (COPD). It contains eight items: dyspnea, anxiety, depressed mood, sleep, energy, daily activities, social activities and sexual life. Psychometric properties were assessed during a clinical trial that evaluated the impact of tiotropium on HRQoL of COPD patients. These included the determination of structure, internal consistency reliability, concurrent validity with the St George's Respiratory Questionnaire (SGRQ), test - retest reliability, clinical validity and responsiveness to change over two weeks. Minimal important difference (MID) was calculated; cumulative response curves (CRC) were based on the dyspnea item. Psychometric analyses showed that VSRQ structure was unidimensional. The questionnaire demonstrated good internal consistency reliability (Cronbach's alpha = 0.84), good concurrent validity with SGRQ (Spearman = -0.70) and clinical validity, good test-retest reproducibility (ICC = 0.77), and satisfactory responsiveness (standardized response mean = 0.57; Guyatt's statistic = 0.63). MID was 3.4; CRC median value of the 'minimally improved' patients was 3.5. In conclusion, VSRQ brevity and satisfactory psychometric properties make it a good candidate for large studies to assess HRQoL in COPD patients. Further validation is needed to extend its use in clinical practice.

[Retinopathy of prematurity in the Murcia region of Spain. Incidence and severity]

OBJECTIVE

To determine the incidence and severity of Retinopathy of Prematurity (ROP) in the Murcia region of Spain.

METHODS

This was a retrospective study of all infants born preterm in the Murcia region during 2004, who were screened for ROP. Our screening criteria were: Infants with a gestational age <or= 32 weeks (GA) or with a birth weight <or= 1500 g (BW). We evaluated sex, GA, BW, parity and ophthalmologic evaluation. We then performed a descriptive study and a statistical analysis.

RESULTS

The study sample involved 115 infants with an average GA of 29.67 weeks and BW of 1325 g. The incidence of ROP and severe ROP was 32.1% and 15.6% respectively. The likelihood of the premature infant developing severe ROP was found to be 88.8% if it was born before 29 weeks GA or weighed less than 1000 g BW. Significant differences (p < 0.001), in terms of GA and BW between infants with and without ROP, were found.

CONCLUSIONS

A third of the preterm infants screened for ROP in the Murcia region developed the disease, and the 50% of these required treatment. The current screening criteria used in our region are appropriate. If more restrictive criteria were used, some severe ROP cases would not be detected. In order to be able to modify the current guidelines for screening for ROP, further studies are required.

Impact of zoledronic acid (Z) on pain in prostate cancer patients with bone metastases in a randomised placebo-control trial

4638

Background: Bone metastases occur in up to 80% of advanced prostate cancer patients and can results in painful Skeletal-Related Events (SREs). Z is the only biphosphonate approved for metastatic prostate cancer that decreases the occurrence of SREs which include pathologic fractures, severe bone pain requiring radiation therapy, spinal cord compression, surgery to bone and hypercalcemia of malignancy which may lead to daily activity limitations. We performed retrospective analyses on data from a placebo-controlled study of Z to investigate which items of the Brief Pain Inventory (BPI) were most sensitive to changes in patient’s pain due to treatment. Methods: Prostate cancer patients with bone metastases received Zoledronate 4 mg (n = 201) or placebo (n = 201). The BPI was administered at baseline (visit 2), and visits 3 (weeks 3–4), 4 (weeks 6–8), and then every second visit (every 6 weeks) until study end. Changes in BPI individual item scores and the Pain Severity and Pain Interference scale scores were compared between Z and placebo groups. Post-baseline missing data was replaced by Last Observation Carried Forward (LOCF). Results: Z was statistically significantly better than placebo for changes in BPI items ‘pain at its worst’, ‘pain at its least’, ‘pain on average’, and the BPI pain severity scale (p < 0.05) at visit 4 (weeks 6–8), and visit 6 (week 12). For ‘pain right now’ there were statistically significant differences at visit 4, but not visit 6. Z was also superior to placebo for ‘pain right now’ and the Pain Severity and Interference scales at visit 12 (week 30–32) (p < 0.05). Finally Z was superior to placebo for ‘interference with general activities’ at visits 12 (week 30–32), 16 (weeks 42–44), and LOCF (p < 0.05). Conclusion: Our findings suggest that Z significantly reduces bone pain and general activity limitations in prostate cancer patients with bone metastases. Several items in the BPI are more sensitive to Z treatment including ‘pain at its worst’, ‘pain at its least’, ‘pain on average’, and the BPI Pain Severity scale.

[Table: see text]

Effect of zoledronic acid (Z) on pain in prostate cancer patients with bone metastases based on performance status

14544

Background: Z has demonstrated efficacy in reducing, preventing, delaying the occurrence of an SRE (Skeletal Related Event) including pathologic fractures, severe bone pain requiring radiation therapy, spinal cord compression, surgery to bone and hypercalcemia of malignancy which could lead to a loss of independence. Effects of Z on pain were analyzed in a subgroup of patients based on performance status. Methods: Subjects were randomised to Z 4mg (n = 201) or placebo (n = 201). The short form of the Brief Pain Inventory (BPI) was administered at baseline (visit 2), and visits 3 (weeks 3–4), 4 (weeks 6–8), and then every second visit (every 6 weeks) until study end. Changes in BPI individual item scores and the Pain severity and Pain Interference scale scores were compared between Z and placebo groups. Post baseline missing data were replaced by Last Observation carried forward (LOCF). Changes in scores were examined in the subgroup of patients with ECOG performance status scores of ≥ 1. Results: For patients ECOG score of ≥ 1 at baseline (n = 227), Z was superior to placebo in the BPI items ‘pain at its worst’, ‘pain at its least’, ‘pain on average’, and the Pain Severity scale at visit 4 (weeks 6–8) and visit 6 (week 12) (p < 0.05). At visit 8 (weeks 18–20) Z was superior to placebo on the ‘pain on average’ item and Pain Severity scale (p < 0.05). For visit 12 (weeks 30–32) and for LOCF Z was superior to placebo for ‘pain at its worst’, ‘pain on average’ and Pain Severity (p < 0.05 for all). For the ‘pain right now’ item there were statistically significant differences at visits 4, 6, 12 and LOCF (p < 0.05). In addition, at visit 6 (week 12), Z was superior to placebo for changes in items assessing interference with: sleep, general activities, mood, walking and enjoyment of life (p < 0.05). Z was also superior to placebo for ‘interference with general activities’ at visits 12 (weeks 30–32), 16 (weeks 42–44) and LOCF (p < 0.05). Conclusion: Results suggest Z provides significant benefit in pain reduction and Z may have an impact on patients’ daily activities which may lead to a preservation of patients’ functionality.

[Table: see text]

LIPSIA--a new software system for the evaluation of functional magnetic resonance images of the human brain

This paper describes the non-commercial software system LIPSIA that was developed for the processing of functional magnetic resonance images (fMRI) of the human brain. The analysis of fMRI data comprises various aspects including filtering, spatial transformation, statistical evaluation as well as segmentation and visualization. In LIPSIA, particular emphasis was placed on the development of new visualization and segmentation techniques that support visualizations of individual brain anatomy so that experts can assess the exact location of activation patterns in individual brains. As the amount of data that must be handled is enormous, another important aspect in the development LIPSIA was the efficiency of the software implementation. Well established statistical techniques were used whenever possible.

[Behavior of some anthropometric, clinical and biochemical variables in boys and girls 8 to 12 years of age from the longitudinal study of the metropolitan area]

A longitudinal principal components analysis was used to summarize trends or intraindividual changes in weight, height, blood pressure, serum cholesterol and triglycerides in 32 boys and 28 girls from the Caracas Longitudinal Study (1976-1982), who started follow-up at age 8. A first component was identified for each variable, it represents a measure of position across the whole age period, a "canalization pattern". This component accounted for most of the total variance. The second component represents an unidirectional change in relative position of the values of the variable, a "decanalization pattern", and a third pattern summarized deviations around a position level: "recanalization pattern". The results from the correlation analyses between the components indicate a positive and significant association between the identified trends. These patterns allow predictability of "high and low risk" factors of non-communicable chronic diseases.

On multivariate spectral analysis of fMRI time series

Most of functional magnetic resonance imaging (fMRI) time series analysis is based on single voxel data evaluation using parametric statistical tests. The result of such an analysis is a statistical parametric map. Voxels with a high significance value in the parametric test are interpreted as activation regions stimulated by the experimental task. However, for the investigation of functional connectivities it would be interesting to get some detailed information about the temporal dynamics of the blood oxygen level-dependent (BOLD) signal. For investigating that behavior, a method for fMRI data analysis has been developed that is based on Wiener theory of spectral analysis for multivariate time series. Spectral parameters such as coherence measure and phase lead can be estimated. The resulting maps give detailed information on brain regions that belong to a network structure and also show the temporal behavior of the BOLD response function. This paper describes the method and presents a visual fMRI experiment as an example to demonstrate the results.

Gestalt perception modulates early visual processing

We examined whether early visual processing reflects perceptual properties of a stimulus in addition to physical features. We recorded event-related potentials (ERPs) of 13 subjects in a visual classification task. We used four different stimuli which were all composed of four identical elements. One of the stimuli constituted an illusory Kanizsa square, another was composed of the same number of collinear line segments but the elements did not form a Gestalt. In addition, a target and a control stimulus were used which were arranged differently. These stimuli allow us to differentiate the processing of colinear line elements (stimulus features) and illusory figures (perceptual properties). The visual N170 in response to the illusory figure was significantly larger as compared to the other collinear stimulus. This is taken to indicate that the visual N170 reflects cognitive processes of Gestalt perception in addition to attentional processes and physical stimulus properties.

Generation of a flexible cell line with regulatable, high-level expression of HIV Gag/Pol particles capable of packaging HIV-derived vectors

HIV-derived vectors are of potential clinical relevance due to their ability to transduce nondividing cells in vitro and in vivo. However, the generation of cell lines stably and reproducibly expressing high amounts of defined subviral particles, capable of packaging and transducing HIV-derived vectors, has been hampered by the cytotoxicity of some of the required gene products, in particular of the HIV-1 protease. The successful use of regulatable gene expression systems to overcome this problem requires that the remaining basally expressed gene product activity is below the threshold for cytotoxicity. To try to achieve this, we have consecutively introduced appropriate plasmids, encoding HIV rev and HIV gag/pol gene products, each under the control of separate ecdysone-inducible promoters, into human 293 cells. Using a protocol in which a specific HIV protease inhibitor, Saquinavir, was continuously present in the culture medium during selection, we could generate stable cell lines inducibly expressing high amounts of subviral particles. A cell line, termed 293-Rev/Gag/Pol(i), which has been characterized in more detail, inducibly releases, within 48 h postinduction, high amounts of HIV Gag/Pol particles (about 10 microg CA/ml). These HIV Gag/Pol particles can package and transduce third-generation HIV vectors to high titers. Thus, in addition to other applications, the 293-Rev/Gag/Pol(i) cell line represents a "founder" packaging cell line which, depending on the requirement, can be further modified to include specific transgene-encoding vector and targeting glycoprotein genes.

[Influential factors in mortality rate from congenital heart disease. Study of 1,216 children in the Autonomous Community of Murcia (1978-1990)]

INTRODUCTION

In the last few years, important progress has taken place in management of congenital heart disease. These changes have had an influence on diagnosis, preoperative management, surgery treatment and postoperative care, giving rise to better results in the treatment of children suffering from congenital heart disease.

AIM

To assess the results of congenital heart diseases in a reference hospital by comparing two periods with reference to both diagnosis and therapeutical management. We also intend to investigate the influence that factors such as the existence of extracardiac congenital malformations and heart surgery have on mortality.

PATIENTS AND METHODS

Our sample group was made up of 1,216 children suffering from congenital heart disease. Their ages ranged from 1 day to 7 years old. These children were born over a period of thirteen years and studied at the paediatric cardiology unit in a reference hospital in the Autonomous Community of Murcia, a region of Spain. We retrospectively analysed their development by individual heart diseases (and their associated factors), and the global results. Our research was divided into two periods: between 1978 and 1983, and between 1984 and 1990. Differences were found regarding diagnosis and treatment.

RESULTS

a) Mortality rate from congenital heart disease decreased in the period between 1984 and 1990 in comparison to the period between 1978 and 1983, from 28 to 21,7% (p < 0.05); b) individually, the mortality rate decreased with statistical significance in two diseases: interventricular communication and patent ductus arteriosus, and c) there is a higher mortality rate of patients with no surgery treatment and/or extracardiac malformations.

CONCLUSION

Progress in the management of congenital heart disease has led to a more favourable outcome in the last years.

Properties of wild-type, C-terminally truncated, and chimeric maedi-visna virus glycoprotein and putative pseudotyping of retroviral vector particles

We have characterized the properties of the maedi-visna virus (MVV) glycoprotein, which has a long cytoplasmic C-terminal domain, and of a panel of C-terminally truncated and C-terminally chimeric MVV-Env constructs. Cells expressing wild-type MVV glycoprotein form syncytia with target cells from many different species and tissues, demonstrating that the MVV-Env cellular receptor is widely distributed. Similar to the situation with other lentiviral glycoproteins, truncation of the C-terminal domain of MVV-Env significantly increases its membrane fusion capacity. However, despite their presence in a fusogenic form at the cell surface, neither the wild-type nor any of the C-terminally modified MVV-Env constructs, these latter lacking sterically inhibitory C termini, were able to successfully pseudotype murine leukemia virus- or human immunodeficiency virus-derived vector particles.

Slow cortical potentials during retention of object, spatial, and verbal information

We used event related potentials (ERPs) to examine both the specificity and the timing of slow cortical scalp potentials (SPs) elicited by the retention of object, spatial, and verbal information in working memory (WM). Participants performed a modified delayed matching task in which a task cue presented in the middle of the delay interval indicated what type of information had to be retained for a subsequent comparison with the test stimulus. The first experiment used nameable objects and spatial locations as stimuli. The retrieval mode (visual vs. verbal) was manipulated by presenting either figural information or printed words as test stimuli. Transient ensembles of frontal and parieto-occipital slow waves with different scalp topographies for object and spatial information were evoked as a function of task cues. When words rather than objects were used as test stimuli highly similar, though more pronounced, fronto-parietal slow wave patterns were obtained. The second experiment using unfamiliar objects and non-nameable spatial locations indicated that neither the left frontal negative SP nor the posterior SPs are exclusively related to verbal working memory operations. The results indicate that a parietal negative SP reflects processes of spatial selective attention whereas a parieto-occipital positive SP indexes the retention of visual object information. Left frontal negative SPs are generated by a compound of higher order frontal control processes and vary as a function of information type.

What have Klingon letters and faces in common? An fMRI study on content-specific working memory systems

Neuroimaging studies show that prefrontal, premotor, and parietal cortical regions are part of a working memory network that supports the active retention of information. In two experiments we used fMRI to examine whether prefrontal and posterior cortical areas are organized in a content-specific way for object and spatial working memory. Subjects performed a delayed matching-to-sample task modified to allow the examination of content-specific retention processes, independent of perceptual and decision-related processes. In Experiment 1, either unfamiliar geometrical objects (Klingon letters from an artificial alphabet unknown to the participants) or their spatial locations had to be memorized, whereas in Experiment 2, either unfamiliar faces or biological objects (butterflies) were actively memorized. All tasks activated a similar cortical network including posterior parietal (banks of the intraparietal sulcus), premotor (banks of the inferior precentral sulcus) and prefrontal regions (banks of the inferior frontal sulcus), and the presupplementary motor area (pre-SMA). For geometrical objects and faces for which strategic semantic processing can be assumed, this activation was larger in the left than in the right hemisphere, whereas a bilateral or right dominant distribution was obtained for butterflies and spatial locations. The present results do not support the process-specific or content-specific view of the role of the prefrontal cortex in working memory task. Rather, they suggest that the inferior prefrontal cortex houses nonmemonic strategic processing systems required for response selection and task management that can flexibly be used across a variety of tasks and informational domains.

Membrane fusion between retroviral particles: host-range extension and vaccine prospects

We have analyzed if different populations of retroviral particles carrying the viral and cellular receptors of membrane viruses, respectively, are able to specifically fuse with each other. Using the glycoprotein of human immunodeficiency virus type 1 and its cellular receptor complex, we demonstrate that interviral membrane fusion can, indeed, occur and that the resultant fused viral structures are able to infect cells and transduce a marker gene. On the one hand, these results have relevance for the development of vaccine strategies based on fusion-induced conformational epitopes on the viral glycoprotein. However, in addition to this potential practical application, the results obtained (which were extended to include analyses with the vesicular stomatitis virus G protein and its cellular receptor) have far-reaching implications for in vivo situations in which simultaneous infections with different membrane viruses can occur.

Statistical analysis of multi-subject fMRI data: assessment of focal activations

A simple procedure for analyzing multi-subject functional magnetic resonance imaging (fMRI) data is proposed. In the first step, a voxel-wise t-test across standardized z-maps is performed to identify areas that are consistently activated across subjects. In the second step, for each area, individual mean z-scores are calculated and subsequently subjected to an analysis of variance. An example is provided.

Incorporation of wild-type and C-terminally truncated human epidermal growth factor receptor into human immunodeficiency virus-like particles: insight into the processes governing glycoprotein incorporation into retroviral particles

Previous results have indicated that incorporation of surface glycoprotein into retroviral particles is not a specific process and that many heterologous viral and cellular glycoproteins can be incorporated as long as they do not have long cytoplasmic C-terminal regions which were presumed to be sterically inhibitory. In this study, this concept has been directly examined by analyzing the incorporation of the wild-type human epidermal growth factor receptor (Wt-EGFR) and of a C-terminally truncated mutant of Wt-EGFR (Tr-EGFR) into human immunodeficiency virus (HIV)-like particles. Incorporation was directly analyzed at the protein level and by immunogold labelling of enriched HIV-like particles. In agreement with the above concept, Tr-EGFR, with only 7 C-terminal amino acids (aa), was efficiently incorporated into HIV-like particles. Incorporation of the Wt-EGFR species, with 542 C-terminal cytoplasmic aa, was reduced by a factor of about 5 in comparison to that of the Tr-EGFR species. However, the Wt-EGFR species was still very significantly present in the HIV-like particles. A series of control experiments verified that this represents genuine incorporation of Wt-EGFR into the membrane of HIV-like particles. These observations allow further speculation as to the processes governing glycoprotein incorporation into retroviral particles and indicate that the internal virus structure of HIV (in particular the matrix layer [MA]) can accommodate much larger heterologous cytoplasmic domains in incorporated glycoproteins than previously assumed.

[Tracking of body height, body weight, body mass index, blood lipids and glucose in upper strata girls in Caracas, Venezuela]

In the Caracas Longitudinal Study, the canalization of 24 girls that started follow-up at age 4, 43 at age 8, and 32 at age 12 in: height (H), weight (W), Body Mass Index (BMI), cholesterol (CHOL), triglycerides (TG) and glucose (GL), was studied using Schneiderman n Tracking Index (TI) and age to age correlations. TI presented a gradient H > W > BMI > CHOL and lower in TG and GL. TI of all variables diminished increased with age and in BMI and CHOL. Age to age correlations were significant at all ages in H, W. and BMI and higher in CHOL (p < 0.01) compared to TG and GL. The significant tracking of H, W, BMI and lipids, specially CHOL, is relevant in prevention of non-communicable chronic diseases.

Inhibition of cellular glycoprotein incorporation into human immunodeficiency virus-like particles by coexpression of additional cellular interaction partner

We examined the concepts of whether cellular surface glycoprotein overexpressed in heterologous cells can be efficiently incorporated into lentiviral particles and whether incorporation is blocked when a natural interaction partner is coexpressed. Human CD4 and a truncated version lacking the cytoplasmic C terminus, expressed in 293T cells, were efficiently incorporated into Env-defective human immunodeficiency virus type 1 virus-like particles. However, on coexpression of p56(lck), the natural binding partner of the CD4 C-terminal domain in T lymphocytes, incorporation of the wild-type CD4 was completely abolished, whereas incorporation of the C-terminally truncated mutant remained unaffected. Confocal microscopy and detergent solubility assays did not reveal any significant difference in the distribution of wild-type CD4 at the plasma membrane in the presence or absence of p56(lck). These results give some insight into the processes governing protein incorporation into the lipid bilayer of lentiviruses.

[The liver as a source of essential long chain polyunsaturated fatty acids for postnatal brain development in the rat]

We address here the issue concerning the origin of essential long chain polyunsaturated fatty acids (LC-PUFA) needed for early postnatal brain development. Normal newborn rats 1, 5, 10 and 20 day-old were decapitated, immediately after, the livers were processed to obtain the microsomal fraction and its delta 6 fatty acid desaturase activity and fatty acid composition were determined. Samples of plasma, whole homogenized brain hemispheres and milk contained in the gastric cavity of the suckling rats, were analyzed to obtained their fatty acid composition. We fond that the rat neonate has a very low delta 6 desaturase activity in liver microsomes as compared with the adult. In contrast, there is a considerable quantity of DHA an AA in the milk, liver microsomes, plasma lipids and brain. In conclusion, we propose that brain DHA and AA cannot be derived substantially through liver synthesis, but through the availability of these preformed fatty acids in the milk. These fatty acids are concentrated in liver microsomes and then secreted into plasma lipid pool to reach finally to brain structures.

Pseudotyping of murine leukemia virus with the envelope glycoproteins of HIV generates a retroviral vector with specificity of infection for CD4-expressing cells

CD4-expressing T cells in lymphoid organs are infected by the primary strains of HIV and represent one of the main sources of virus replication. Gene therapy strategies are being developed that allow the transfer of exogenous genes into CD4(+) T lymphocytes whose expression might prevent viral infection or replication. Insights into the mechanisms that govern virus entry into the target cells can be exploited for this purpose. Major determinants of the tropism of infection are the CD4 molecules on the surface of the target cells and the viral envelope glycoproteins at the viral surface. The best characterized and most widely used gene transfer vectors are derived from Moloney murine leukemia virus (MuLV). To generate MuLV-based retroviral gene transfer vector particles with specificity of infection for CD4-expressing cells, we attempted to produce viral pseudotypes, consisting of MuLV capsid particles and the surface (SU) and transmembrane (TM) envelope glycoproteins gp120-SU and gp41-TM of HIV type 1 (HIV-1). Full-length HIV-1 envelope glycoproteins were expressed in the MuLV env-negative packaging cell line TELCeB6. Formation of infectious pseudotype particles was not observed. However, using a truncated variant of the transmembrane protein, lacking sequences of the carboxyl-terminal cytoplasmic domain, pseudotyped retroviruses were generated. Removal of the carboxyl-terminal domain of the transmembrane envelope protein of HIV-1 was therefore absolutely required for the generation of the viral pseudotypes. The virus was shown to infect CD4-expressing cell lines, and infection was prevented by antisera specific for gp120-SU. This retroviral vector should prove useful for the study of HIV infection events mediated by HIV-1 envelope glycoproteins, and for the targeting of CD4(+) cells during gene therapy of AIDS.

Transfer of endoplasmic reticulum and Golgi retention signals to human immunodeficiency virus type 1 gp160 inhibits intracellular transport and proteolytic processing of viral glycoprotein but does not influence the cellular site of virus particle budding

In this study, specific signals known to mediate endoplasmic reticulum or Golgi localization of transmembrane proteins have been transferred to the human immunodeficiency virus type 1 (HIV-1) env gene product. The intracellularly retained recombinant glycoproteins were not proteolytically processed to gp120 and gp41, which is further evidence that this process occurs at a later stage in the transport pathway, presumably within or near the trans-Golgi network. Since the subcellular localization of the viral glycoproteins of enveloped viruses can be one of the factors determining the cellular site of particle assembly and release, experiments were performed to determine if this property was altered by coexpression of the recombinant HIV-1 glycoproteins. When wild-type virus was compared to mutant virus encoding the intracellularly retained glycoproteins, the extent of HIV-1 particle release into the extracellular medium remained unaffected, and electron-microscopic analysis did not reveal any significant alteration in the cellular sites of particle assembly and budding. Thus, in COS-7 cells, altered subcellular localization of the viral glycoprotein does not exert a dominant influence on the assembly site of the HIV-1 particle.

Analysis of vif-defective human immunodeficiency virus type 1 (HIV-1) virions synthesized in 'non-permissive' T lymphoid cells stably infected with selectable HIV-1

In order to facilitate analyses of the molecular function of the human immunodeficiency virus type 1 (HIV-1) Vif protein, we have developed a cell culture model-system which allows permanent production of genotypically and phenotypically vif-defective HIV-1 virions in 'non-permissive' H9 cells. Using recombinant, replication-competent HIV-1 proviruses coding for a selectable marker gene (gpt) instead of nef, two stably infected H9 subclones named M2 (vif-mutant) and WX (wild-type), respectively, were generated. Virions released from cell line M2--displaying the expected vif-defective phenotype--are produced permanently, and in an at least 50 times higher amount than virus particles from acutely vif-negative HIV-1-infected H9 cells. Analysis of viral protein composition and the electron-microscopic morphology of vif-mutant virions did not reveal any detectable differences in comparison to wild-type virions.

Complement activation by HIV-1-infected cells: the role of transmembrane glycoprotein gp41

To characterize the mechanisms of complement activation by human immunodeficiency virus type 1 (HIV-1)-infected cells, Cl-4 cells stably expressing the envelope glycoproteins of HIV-1 and the parent African green monkey cell line CV-1 were tested for C1q binding and complement activation. While the parent cell line CV-1 only showed a weak spontaneous activation of the alternative pathway, Cl-4 cells additionally triggered the classical pathway of complement activation independent of anti-HIV antibodies by direct C1q binding. Earlier studies had shown different complement activating potential of cells infected with various HIV isolates. Recombinant soluble CD4-induced shedding of gp120 from the surface of HIV-1-infected cells converted a weak activator isolate (MVP-899) into a strong complement activator. The increase in complement activation was paralleled by the concomitant unmasking of a previously hidden gp41 epitope comprising the major complement-activating domain of gp41 (aa. 601-613). Our results strongly suggest that the transmembrane protein gp41 induces the activation of complement on the surface of infected cells as has been described previously for purified HIV-1 virions. Furthermore, we present evidence that the different potential of HIV isolates to activate the complement system on the cell surface is caused by different degrees of spontaneous gp120 shedding by various HIV isolates.

Early response to the effect of iron fortification in the Venezuelan population

In Venezuela a severe economic crisis beginning in 1983 provoked a progressive reduction of the quality and quantity of food consumed by the low socioeconomic strata of the population. In these strata, which represent > or = 80% of the Venezuelan population, we had seen a continuous increase in the prevalence of iron deficiency during that recent decade. As a result, in 1993 the Venezuela Government created the Special Commission for Enrichment of Foods. That same year a fortification program began in which precooked yellow and white maize and wheat flours were enriched with 20 and 50 mg Fe (as ferrous fumarate)/kg flour, respectively. The corn flour was also enriched with vitamin A, thiamine, riboflavin, and niacin, whereas the wheat flour was enriched with these same vitamins, except vitamin A. These two cereals represent 45% of the total energy consumed daily by the low socioeconomic strata of the population. A preliminary survey carried out in Caracas in 1994 in a population of 307 children aged 7, 11, and 15 y showed that the prevalence of iron deficiency determined by measuring the serum ferritin concentration and the prevalence of anemia were reduced from 37% and 19%, respectively, in 1992 to 15% and 10%, respectively in 1994.

Dietary fatty acids in athero-thrombogenesis: influence of palm oil ingestion

Dietary experiments, performed in metabolic wards, gave rise to predictive regression equations relating changes of plasma cholesterol concentration to the intake of fatty acids of the diet. It has been established that polyunsaturated fatty acids diminish and most saturated fatty acids increase plasma cholesterol concentration. This information led to expect that dietary use of palm oil may induce an unfavorable plasma lipoprotein profile. This has not been the case as shown in various dietary experiments. The reasons for this discrepancy is discussed. The influence of palm oil enriched diets on prothrombotic variables show that platelets are not affected in their function during prolonged dietary intervention. It is important to continue research on the effects of palm oil based diet on plasma fibrinogen, factor VII. There is still discordant information in this field.

Unimpaired function of a naturally occurring C terminally truncated vif gene product of human immunodeficiency virus type 1

In approximate 10 percent of natural human immunodeficiency virus 1 (HIV-1) vif gene populations, sequences of shortened vif open reading frames with premature stop codons have been found. Here we report the functional analysis of two patient-derived vif genes. Vif45-2 encodes a C terminally truncated Vif protein of only 173 instead of 192 amino acids and additionally contains several rare amino acid substitutions which are in part shared by vifA65-5. HIV-1 pNL4-3-derived recombinant A45-2 and A65-5 virions were fully infectious in H9 cells and human PBMC, both known to be non-permissive for vif-defective HIV-1. Furthermore, A45-2 virions produced in primary human monocyte-derived macrophages were infectious for MT-4 cells. This study unequivocally demonstrates that the C-terminal region (19 amino acids) of the Vif protein is dispensable for Vif function in the in vitro cell culture systems employed. Additionally, we investigated whether the Vif protein might be phosphorylated in vivo and obtained no evidence for this.

Generation of lymphocyte cell lines coexpressing CD4 and wild-type or mutant HIV type 1 glycoproteins: implications for HIV type 1 Env-induced cell lysis

To gain more insight into the processes leading to HIV-1 Env-induced cell death, we aim to coexpress stably wild-type and relevant mutant variants of both HIV-1 Env and human CD4 in lymphocyte cell lines. Here we report on the generation and characterization of several cell lines inducibly or constitutively expressing wild-type or cleavage-defective HIV-1 glycoproteins and human CD4 either singly or in combination. Coexpression of CD4 and wild-type Env led to the formation of multinucleated syncytia, to growth arrest and cell death, effects that all could be prevented by cultivation in the presence of monoclonal antibodies that inhibit cell surface membrane fusion. Cell lines coexpressing CD4 and mutated, noncleavable Env, detectable at the cell surface and still retaining CD4-binding capacity, were not retarded in their growth and cytolysis did not occur. These results indicate that cell lysis requires cell surface interaction of CD4 and gp120/41 and cleavage of gp160 to gp120 and gp41.

Glycoprotein incorporation and HIV-1 infectivity despite exchange of the gp160 membrane-spanning domain

We have examined the role of the membrane-anchoring domain of the HIV-1 glycoproteins in viral glycoprotein function, glycoprotein incorporation, and viral infectivity. For this purpose, we initially exchanged the entire membrane-spanning region with that from a cellular glycoprotein (CD22). Subsequently, the strictly conserved arginine in the central position of the transmembranal alpha-helix was replaced by a neutral residue (R696 --> I696). We have further examined the requirements within the cytoplasmic C-terminus for glycoprotein incorporation and replaced this region of gp160 with the long cytoplasmic C-terminus (118 amino acids) from CD22. Our results show that the specific amino acid sequence of the membrane-spanning region of gp160 is not necessary for viral infectivity, thus making it unlikely that this region is specifically involved in membrane fusion, in glycoprotein incorporation, or in infectivity of the cell lines tested. In contrast, recombinant gp160 with the CD22 C-terminal region, although present at the cell surface and membrane fusion-competent, was excluded from incorporation into particles. This could indicate that steric exclusion, and no pseudotyping, occurs when the heterologous, cytoplasmic C-terminal region is too long and not fitting.

Dietary fish oil affects food intake, growth and hematologic values of weanling rats

The object of this study was to evaluate the effect of increasing amounts of dietary fish oil on growth and hematological variables of the weanling male Sprague-Dawley rat. Animals were fed diets containing either fish oil (FO) or sesame oil (SO) at 5, 10 or 15% (w/w) for 31 d. Growth retardation and reduced food intake was noted in groups fed FO. Hemoglobin (Hb) concentration diminished when the dietary FO was above 5% (w/w). FO is a poor source of (n-6) fatty acids. We postulate that a partial deficiency in (n-6) polyenic family, is a consequence of the increasing amounts of FO in the diets, that may affect growth and erytropoiesis. In this report we show evidence supporting the hypothesis that diets enriched with fish oil can alter normal growth and induced hematological changes in the male weanling rat.

The relationship between iron deficiency and anemia in Venezuelan children

The iron status of 3228 subjects from the nutrition survey Proyecto Venezuela was studied. The sample included children from 1 to 16 y of age grouped by age and sex. Values for three indicators of iron status were compared: hemoglobin concentration, serum ferritin concentration, and percentage saturation of serum transferrin. In all groups there was a strong overlap in the hemoglobin concentration distribution curves for non-iron-deficient and iron-deficient subjects classified as such according to the other two indexes. The prevalence of iron deficiency ranged from 35% in 1-3 y olds to 10% in adolescent males, the values being almost identical in the nonanemic group compared with the total population. In the different groups, 80-97% of the subjects with abnormal values of at least one of these two indexes were not anemic. The difficulties involved in establishing a state of iron deficiency according to these indexes are discussed.

Analysis of protein expression and virus-like particle formation in mammalian cell lines stably expressing HIV-1 gag and env gene products with or without active HIV proteinase

Cell lines stably releasing noninfectious virus-like particles containing wild type or mutant gene products represent useful tools for a biochemical, immunological, and structural analysis of virus assembly. Human immunodeficiency virus (HIV) type 1 gag and env gene products were transiently and stably expressed in mammalian cells and the formation of virus-like particles incorporating viral glycoproteins was analyzed. Transient cotransfection of plasmids directing the synthesis of gag and env gene products yielded efficient release of particles but specific incorporation of HIV glycoproteins was not detected. A stable cell line expressing wild type HIV-1 glycoproteins was generated and transient transfection of this cell line with gag-encoding constructs led to the release of virus-like particles incorporating HIV surface and transmembrane glycoproteins. Attempts to establish stable cell lines expressing wild type HIV gag and pol genes were unsuccessful and only highly unstable lines primarily expressing uncleaved precursor polyproteins were obtained. This result appears to be caused by the cytotoxic effects of the viral proteinase since stable lines were readily selected after transfection of constructs either encoding an inactive mutant of the proteinase or a mutated frameshift signal which prevented expression of the pol reading frame. Stable coexpression of uncleaved Gag polyprotein and wild type env gene products yielded efficient release of immature virus-like particles incorporating HIV glycoproteins. Electron micrographs revealed lentiviral budding structures with the typical surface projections of viral glycoprotein oligomers.

Inhibition of furin-mediated cleavage activation of HIV-1 glycoprotein gp160

The envelope glycoprotein of human immunodeficiency virus (HIV) initiates infection by mediating fusion of the viral envelope with the cell membrane. Fusion activity requires proteolytic cleavage of the gp160 protein into gp120 and gp41 at a site containing several arginine and lysine residues. Activation at basic cleavage sites is observed with many membrane proteins of cellular and viral origin. We have recently found that the enzyme activating the haemagglutinin of fowl plague virus (FPV), an avian influenza virus, is furin. Furin, a subtilisin-like eukaryotic endoprotease, has a substrate specificity for the consensus amino-acid sequence Arg-X-Lys/Arg-Arg at the cleavage site. We show here that the glycoprotein of HIV-1, which has the same protease recognition motif as the FPV haemagglutinin, is also activated by furin.

HIV-1-induced cytopathogenicity in cell culture despite very decreased amounts of fusion-competent viral glycoprotein

In order to examine the potential role of env-induced membrane fusion in the cytopathogenic properties of HIV-1 in cell culture, the effects of mutations within the proteolytic cleavage site of gp160, which result in a reduction but not a complete absence of proteolytic processing have been further studied. Cells expressing the mutant glycoproteins were shown to be severely reduced in their capacity to form syncytia. However, viruses encoding these glycoproteins could infect cell culture cells, albeit with delayed kinetics, and, at late infection time points, resulted in complete cytolysis of the infected culture. Since amplification by polymerase chain reaction and direct sequencing of the DNA in the infected cultures confirmed the presence of the mutant and the absence of revertant DNA, this shows that the amount of fusion competent viral glycoprotein does not influence HIV-1 cytopathogenicity, but rather that other parameters must be involved in inducing cell death.

Expression of biologically active HIV glycoproteins using a T7 RNA polymerase-based eucaryotic vector system

Bacteriophage T7 RNA polymerase and a derivative containing a nuclear localization signal were transiently expressed in CV-1 cells and were shown to localize to the cytoplasm and nucleus, respectively. A vector was constructed containing T7 promoter and transcription terminator sequences flanking a picornaviral 5' untranslated sequence for cap-independent translation and a polyA signal. Expression of the HIV-1 envelope glycoproteins in this vector system gave high levels of specific transcripts and translation products, independent of the subcellular localization of T7 RNA polymerase. The synthesis of HIV glycoproteins was also completely independent of the coexpression of the HIV rev protein, which is normally required for the expression of HIV structural proteins. In addition, a polyA signal was not required, whereas the presence of the picornaviral 5' untranslated region was necessary for efficient expression. Different possibilities to account for these findings are discussed. The HIV glycoproteins synthesized in this system were normally processed and assembled; they could induce syncytium formation and complement an env-deletion mutant of HIV-1.

Retained in vitro infectivity and cytopathogenicity of HIV-1 despite truncation of the C-terminal tail of the env gene product

Five in-frame stop mutations in the HIV-1 env gene, which lead to the production of env gene products truncated within the cytoplasmic C-terminal tail, have been generated and their effects on membrane fusion capacity, glycoprotein incorporation into virus particles, infectivity, and cytopathogenicity were analyzed. The resulting truncated glycoproteins were processed normally, were transported to the cell surface, and were able to induce CD4-dependent membrane fusion. The membrane fusion capacity of one of the mutant glycoproteins with a truncation of 144 amino acids was increased to about double of that induced by wild-type glycoprotein. With a single exception, the truncated viral glycoproteins were incorporated into virus particles which were infectious and cytopathic for permissive MT-4 cells. The infection kinetics with the mutated viruses were, however, delayed to varying degrees in comparison to infection with wild-type virus. Nevertheless, in each case, PCR amplification and direct sequencing of viral DNA in the infected cultures confirmed the presence of the mutant and the absence of revertant DNA. The mutant virus encoding a viral glycoprotein with the longest truncation (144 amino acids), in which only 7 cytoplasmic C-terminal amino acids in gp41 remain, resulted in infection kinetics in MT-4 cells which were only marginally delayed in comparison to those induced by wild-type virus. This means that these C-terminal 144 amino acids of gp41 are not necessary for glycoprotein incorporation into virus particles nor do they significantly contribute to the infectivity nor the cytopathogenicity of HIV-1 in MT-4 cells.

Mutational analysis of the human immunodeficiency virus type 1 env gene product proteolytic cleavage site

The structural requirements for proteolytic cleavage of the human immunodeficiency virus type 1 env gene product, gp160, to gp120 and gp41 have been assessed by specific mutagenesis of the sequence Lys Ala Lys Arg Arg Val Val Glu Arg Glu Lys Arg located between amino acids 500 and 511, i.e., at the putative C terminus of gp120. The basic amino acids underlined have been mutated, individually and in combination, to neutral amino acids, and the cleavability of the mutated env gene products was examined after expression in CV-1 cells. The results show that the replacement of Arg-511 (cleavage presumably occurs C terminal to this amino acid) with Ser completely abolishes recognition and cleavage by the cellular protease(s), i.e., the remaining basic amino acids in the vicinity do not serve as alternative substrates. However, Arg-508 and Lys-510 are important features of the recognition site since, when they are individually changed to neutral amino acids, cleavage is severely impaired. The basic amino acids 500, 502, and 504 are, individually, not important for cleavage, since their individual replacement by neutral amino acids does not impair cleavage. However, when all four basic amino acids 500, 502, 503, and 504 are changed to neutral amino acids, cleavage is almost completely abolished. This shows that the sequence Arg Glu Lys Arg at the cleavage site is alone not sufficient for cleavage but that a contribution of other amino acids is required, whether the other amino acids provide a basic character or a certain structure in the vicinity of the cleavage site. When noncleavable or poorly cleavable mutant env genes are expressed from the infectious plasmid pNL4-3 in CD4+ human lymphoblastoid cells, noninfectious virus, incapable of spread throughout the culture, is produced.

The duck hepatitis B virus P-gene codes for protein strongly associated with the 5'-end of the viral DNA minus strand

A number of antisera, elicited against different segments of the duck hepatitis B virus (DHBV) P-gene translation product, were used to immunoprecipitate the protein that is covalently bound to the 5'-end of the DHBV DNA minus strand. For monitoring purposes, a small DNA minus-strand fragment, carrying this protein, was radioactively labeled. All of the P-specific antisera specifically immunoprecipitated this DNA fragment demonstrating that the protein species attached to the immunoprecipitated DNA fragment were products of the DHBV P-gene. The electrophoretic behavior, in SDS gels, of the DNA minus-strand fragment-protein complex indicated that it was present mostly in the form of aggregates. However, a small fraction consisted of DNA minus-strand fragments carrying P-gene proteins, encoded solely within the 5'-region of the P-gene. This indicated that different P-gene proteins, presumably covalently bound at a common region and subsequently processed, were bound to the 5'-end of the DHBV DNA minus strand. The DHBV P-gene presumably codes for the virus-associated reverse transcriptase and DNA polymerase activities. Using the P-gene-specific antisera, it was not possible to detect putative P-gene-coded polymerase proteins in a free form, i.e., not bound to viral DNA. This may be due to insufficient sensitivity or to the polymerase protein(s) being heterogeneous and/or aggregated. In addition, it is possible that the genome-bound protein itself may have polymerase activity.

[Fats in the diet]

Fats are important constituents of the human diet since on the one hand, they contribute to the caloric density of the diet, and on the other, they serve as vehicles of essential nutrients such as linoleic and alpha-linolenic acids, as well as fat-soluble vitamins. The existence of human populations subsisting on diets with values as low as 10% or more than 50% of the calories represented by fats, has been documented, demonstrating the great adaptability of man to a wide availability of this type of food. Nevertheless, extensive epidemiological and experimental research in relation to a frequent degenerative diseases of man, arteriosclerosis, have consistently demonstrated that the proportion of saturated fats in the diet has a positive correlation with the frequency of these alterations. Mortality and fat availability in Latin America is consistent with these results. In consequence, and taking into consideration the present level of fat availability in the Region, we propose that no more than 25% of the caloric requirement should be covered by fats. Additionally, this amount of fat should have equal proportions of saturated, monounsaturated and polyunsaturated fatty acids. Cholesterol, which is contained in animal fats, is not a necessary nutrient for humans, so that no minimum consumption needs to be established. Daily ingestion of cholesterol should be restrained to no more than 100 mg/1,000 calories. Introduction of new fatty foods for human consumption should be preceded by a thorough investigation of the metabolic consequences.

The duck hepatitis B virus DNA polymerase is tightly associated with the viral core structure and unable to switch to an exogenous template

The duck hepatitis B virus (DHBV) has a DNA polymerase associated with it which uses the incomplete viral genome as endogenous template. A prerequisite for studying this polymerase is the availability of conditions to open viral cores without destroying their enzymatic activity. In this study, this was achieved by a brief treatment with low pH. DHBV DNA in low-pH-treated cores was susceptible to digestion with deoxyribonuclease I and restriction enzymes, and large restriction fragments diffused out of the viral cores. However, the DHBV polymerase remained tightly associated with its DNA template in the viral core structure and could still incorporate nucleotides into those DNA fragments which carried the DNA-bound protein and remained in the core. The DHBV polymerase could not switch to any of several exogenously supplied templates although these were most likely accessible to it. The manner in which this tight association of the DHBV polymerase with the core may occur, and the possible implications of this interaction during the DHBV replication cycle, is discussed.

Differential expression of endogenous virus glycoprotein in fibroblasts and sera of some adult chickens

A rapid and convenient assay for the expression of endogenous retrovirus glycoprotein in adult chickens has been developed based on the enzyme-linked immunosorbent assay (ELISA) principle. This method has been standardized using the conventional chick helper factor test. In the course of establishing this method with a large number of specific pathogen-free (VALO) chickens, an interesting diversity became apparent; about 20% of the birds which, according to chick helper factor tests performed with feather follicle fibroblast cultures were negative for endogenous virus glycoprotein expression, exhibited relatively high titres of reactive glycoprotein in serum. However, in no case was a chick helper factor-positive animal negative in serological tests. The possibility of endogenous virus antigen expression which either cannot be detected in fibroblasts, or is incapable of functioning in the chick helper factor complementation, is discussed.

Lipid transport across the intestinal epithelial cell. Effect of colchicine

Rats injected with colchicine (0.5 mg/100 g of body weight) 1 h before ingestion of a margarine emulsion (1 g in 2 ml of saline) do not show the rise in plasma triacylglycerol concentration found in controls during the subsequent hours. The effect of colchicine is more dramatic when the experiment is performed after prior administration of Triton WR-1339, a substance known to inhibit the catabolism of lipoproteins. Colchicine-treated rats also showed a five-fold increase in the content of triacylglycerol in proximal jejunum, when compared to controls. These results are consistent with the idea that colchicine interferes with the intracellular phase of fat absorption, suggesting that the microtubular-microfilamentous system could be involved in the release of chylomicrons from the intestinal cell into the circulation.

Antigenic determinants of murein lipoprotein and its exposure at the surface of Enterobacteriaceae

Murein lipoprotein from the outer membrane of Escherichia coli could be fixed to erythrocytes without pretreatment of the erythrocytes. Passive hemagglutination or immune hemolysis could thus be used as sensitive assays to determine antibodies against lipoprotein. In rabbit antisera prepared against whole cells of E. coli, Salmonella, Arizona, and Shigella antibodies against lipoprotein were present. The respective titers were lowest in encapsulated smooth strains and highest in rough mutants. Antisera against deep rough mutants showed even higher anti-lipoprotein titers than anti-R-lipopolysaccharide titers. Correspondingly,absorption of lipoprotein antibodies with enterobacterial strains was most pronounced with deep rough mutants and lowest with smooth strains. Lipoprotein becomes increasingly an immunogen as well as an antigen the more sugar residues are missing in the lipolysaccharide on the cell surface. In wild-type cells lipoprotein is buried in the outer membrane; its exposure in mutant cells is related to defects at the cell surface.