The chaperone micronemal protein Hsp70-1 from Plasmodium berghei ookinetes is shed during gliding on solid surface sustrata

Plasmodium the causative agent of malaria is a member of the phylum Apicomplexa, where all invasive forms have a substrate-dependent motility called gliding, key to malaria transmission. Gliding allows parasite host-cell recognition, binding, cell entry and trespassing the cytoplasm. In this process Plasmodium releases molecules from micronemes and the cell surface that are deposited on trails left behind on the substratum as the parasite progresses. Previously we identified the heat shock protein 70-1 (HSP 70-1) on the surface and micronemes of P. berghei ookinetes, the parasite form that invades the mosquito midgut. To investigate if this protein is shed of from the parasite during invasion, we searched HSP 70-1 in gliding trails deposited on a solid surface by P. berghei ookinetes.

Participation of Glutamatergic Ionotropic Receptors in Excitotoxicity: The Neuroprotective Role of Prolactin

Glutamate (Glu) is known as the main excitatory neurotransmitter in the central nervous system. It can trigger a series of processes ranging from synaptic plasticity to neurophysiological regulation. To carry out its functions, Glu acts via interaction with its cognate receptors, which are ligand-dependent. Glutamatergic receptors include ionotropic and metabotropic categories. The first allows the passage of ions through the postsynaptic membrane, while the metabotropic subtype activates signaling cascades through second messengers. It is well known that an excess of extracellular Glu concentration induces overstimulation of ionotropic glutamatergic receptors (iGluRs), causing the excitotoxicity phenomenon that leads to neuronal damage and cell death. Excitotoxicity plays a crucial role in different brain pathologies such as brain strokes, epilepsy and neurodegenerative disorders. However, until now, there are no effective neuroprotective compounds to prevent or rescue neurons from excitotoxicity. Thus, the continuous elucidation of the molecular mechanisms underlying excitotoxicity in order to prevent damage or neuronal death is necessary. Therefore, the aim of this review was to summarize the current knowledge regarding iGluRs, while describing their structures and molecular mechanisms of action, including their role in excitotoxicity, as well as the current strategies to reduce excitotoxic damage. Particularly, strategies mediated by prolactin, a somatotropin family-related hormone that displays a significant neuroprotective effect against both Glu and kainic acid-induced excitotoxicity in the hippocampus, are described. Finally, the role of prolactin as a possible molecule in the treatment of excitotoxicity in neurological diseases is discussed.

Modulation of host plant immunity by Tobamovirus proteins

BACKGROUND

To establish successful infection, plant viruses produce profound alterations of host physiology, disturbing unrelated endogenous processes and contributing to the development of disease. In tobamoviruses, emerging evidence suggests that viral-encoded proteins display a great variety of functions beyond the canonical roles required for virus structure and replication. Among these, their modulation of host immunity appears to be relevant in infection progression.

SCOPE

In this review, some recently described effects on host plant physiology of Tobacco mosaic virus (TMV)-encoded proteins, namely replicase, movement protein (MP) and coat protein (CP), are summarized. The discussion is focused on the effects of each viral component on the modulation of host defense responses, through mechanisms involving hormonal imbalance, innate immunity modulation and antiviral RNA silencing. These effects are described taking into consideration the differential spatial distribution and temporality of viral proteins during the dynamic process of replication and spread of the virus.

CONCLUSION

In discussion of these mechanisms, it is shown that both individual and combined effects of viral-encoded proteins contribute to the development of the pathogenesis process, with the host plant's ability to control infection to some extent potentially advantageous to the invading virus.

Validity of the Ages and Stages Questionnaire to detect risk of Developmental Coordination Disorder in preschoolers

BACKGROUND

A reliable and valid screening tool for detecting children at risk for Developmental Coordination Disorder (DCD) is needed. The purpose of this study was to evaluate the ability of the Ages and Stages Questionnaire-Third Edition (ASQ-3) motor scales to detect children at risk for DCD in a community-based sample of children aged 3.5-5.5 years.

METHODS

One hundred and sixty parent-child pairs were recruited from community-based organizations. Children were eligible if they spoke English and had no known physical impairments. Eligible parents were asked to fill out the ASQ-3, following which their child's fine motor and gross motor proficiency was assessed using the Movement Assessment Battery for Children-Second Edition (MABC-2). DCD risk was defined as those children scoring at or below the 16th percentile on the MABC-2. Sensitivity and specificity of the fine and gross motor areas of the ASQ-3 were examined and referenced against the DCD risk classification.

RESULTS

The ASQ-3 total motor score correlated moderately with overall standard score on the MABC-2 (r = 0.41; p < 0.001). Regardless of the ASQ-3 cut-off used, sensitivities of the ASQ-3 fine motor or gross motor scale to detect DCD risk were low at 21-47%, whereas specificities were high at 89-96%.

CONCLUSION

Early identification of motor skill delays is important in order to intervene and hopefully prevent the associated negative health consequences. However, because of the low sensitivity of the ASQ-3 motor scales, these results suggest that the ASQ-3 is not an appropriate screening tool to identify children at risk for DCD in the preschool population.

Transgenic expression of Tobacco mosaic virus capsid and movement proteins modulate plant basal defense and biotic stress responses in Nicotiana tabacum

Plant viruses cause metabolic and physiological changes associated with symptomatic disease phenotypes. Symptoms involve direct and indirect effects, which result in disruption of host physiology. We used transgenic tobacco expressing a variant of Tobacco mosaic virus (TMV) coat protein (CP(T42W)) or movement protein (MP), and a hybrid line (MP×CP(T42W)) that coexpresses both proteins, to study the plant response to individual viral proteins. Findings employing microarray analysis of MP×CP(T42W) plants and silenced mp×cp(T42W)* controls revealed that altered transcripts were mostly downregulated, suggesting a persistent shut-off due to MP×CP(T42W) expression. Next, we showed that MP triggered reactive oxygen species (ROS) accumulation, reduction of total ascorbate, and expression of ROS scavenging genes. These effects were enhanced when both proteins were coexpressed. MP and MP×CP(T42W) plants showed increased levels of salicylic acid (SA) and SA-responsive gene expression. Furthermore, these effects were partially reproduced in Nicotiana benthamiana when GMP1 transcript was silenced. CP(T42W) seems to be playing a negative role in the defense response by reducing the expression of PR-1 and RDR-1. MP and MP×CP(T42W) transgenic expression promoted a recovery-like phenotype in TMV RNA infections and enhanced susceptibility to Pseudomonas syringae and Sclerotinia sclerotiorum. The individual effects of viral proteins may reflect the ability of a virus to balance its own virulence.

South American Heart Transplantation Registry of patients receiving everolimus in their immunosuppressive regimens

The increasing number of heart transplant recipients receiving immunosuppression with mammalian target of rapamycin inhibitors prompted the implementation of a South American Transplant Physicians Group to register these patients in a database. Everolimus (EVL) is a signal proliferation inhibition that reduces graft vascular disease when used de novo. Recently, its administration has expanded to subjects with resistant rejection or with side effects due to other immunosuppressive drugs (calcineurin inhibitors and/or steroids), allowing for better regulation of the immunosuppressive regimen. Herein we have shown the data collected from patients receiving EVL in ten South American Heart Transplant Centers. We have concluded that the administration of EVL is a useful adjunctive therapy that allows the reduction or suspension of other immunosuppressive drugs that caused unwanted side effects, without a loss of immunosuppressive efficacy, with manageable side effects, and constituting a valuable therapeutic option.

Estimating the impact of alcohol consumption on survival for HIV+ individuals

Alcohol consumption is associated with decreased antiretroviral adherence, and decreased adherence results in poorer outcomes. However the magnitude of alcohol's impact on survival is unknown. Our objective was to use a calibrated and validated simulation of HIV disease to estimate the impact of alcohol on survival. We incorporated clinical data describing the temporal and dose-response relationships between alcohol consumption and adherence in a large observational cohort (N=2,702). Individuals were categorized as nondrinkers (no alcohol consumption), hazardous drinkers (consume > or =5 standard drinks on drinking days), and nonhazardous drinkers (consume <5 standard drinks on drinking days). Our results showed that nonhazardous alcohol consumption decreased survival by more than 1 year if the frequency of consumption was once per week or greater, and by 3.3 years (from 21.7 years to 18.4 years) with daily consumption. Hazardous alcohol consumption decreased overall survival by more than 3 years if frequency of consumption was once per week or greater, and by 6.4 years (From 16.1 years to 9.7 years) with daily consumption. Our results suggest that alcohol is an underappreciated yet modifiable risk factor for poor survival among individuals with HIV.

Distribution of alpha1-antitrypsin PI S and PI Z frequencies in countries outside Europe: a meta-analysis

The objective of the present study was to review published surveys on allelic frequencies S and Z in countries outside Europe to evaluate the validity of the reported data. Studies on the topic, published from 1965 to May 2001, were retrieved using MEDLINE and bibliographic reference consultations. The criteria for the selection of the studies were the following: 1) sample size >or=250 individuals; 2) alpha1-antitrypsin phenotype determination performed by means of crossed antigen-antibody, isoelectric focusing in polyacrylamide gels, or polymerase chain reaction (PCR); 3) PI type determination performed without any previous screening procedure; 4) S and Z 95% CI of the reported outcomes within the limits of a calculated coefficient of variation. Forty-three out of 85 studies comply with the established criteria for being analysed. Worldwide maps of geographical distributions of PI S and PI Z frequencies have been designed by the authors by adding the data provided by these 43 selected studies to the 70 reported in a recent European meta-analysis.

Relative contribution of CYP3A to amitriptyline clearance in humans: in vitro and in vivo studies

The relative contribution of cytochrome P450 3A (CYP3A) to the oral clearance of amitriptyline in humans has been assessed using a combination of in vitro approaches together with a clinical pharmacokinetic interaction study using the CYP3A-selective inhibitor ketoconazole. Lymphoblast-expressed CYPs were used to study amitriptyline N-demethylation and E-10 hydroxylation in vitro. The relative activity factor (RAF) approach was used to predict the relative contribution of each CYP isoform to the net hepatic intrinsic clearance (sum of N-demethylation and E-10 hydroxylation). Assuming no extrahepatic metabolism, the model-predicted contribution of CYP3A to net intrinsic clearance should equal the fractional decrement in apparent oral clearance of amitriptyline upon complete inhibition of the enzyme. This hypothesis was tested in a clinical study of amitriptyline (50 mg, p.o.) with ketoconazole (three 200 mg doses spaced 12 hours apart) in 8 healthy volunteers. The RAF approach predicted CYP2C19 to be the dominant contributor (34%), with a mean 21% contribution of CYP3A (range: 8%-42% in a panel of 12 human livers). The mean apparent oral clearance of amitriptyline in 8 human volunteers was decreased from 2791 ml/min in the control condition to 2069 ml/min with ketoconazole. The average 21% decrement (range: 2%-40%) was identical to the mean value predicted in vitro using the RAF approach. The central nervous system (CNS) sedative effects of amitriptyline were slightly greater when ketoconazole was coadministered, but the differences were not statistically significant. In conclusion, CYP3A plays a relatively minor role in amitriptyline clearance in vivo, which is consistent with in vitro predictions using the RAF approach.

Identification of differentially regulated genes of Plasmodium by suppression subtractive hybridization

Plasmodium, the causative agent of malaria, has many morphologically and functionally distinct developmental stages. In the mosquito host alone, there are five transitions during the development of a gametocyte into a sporozoite. Determining which genes are expressed at the different developmental stages is vital to our understanding of the parasite. There are a growing number of techniques designed to study gene expression, including microarray. Here, Johannes Dessens, Gabrielle Margos, Maria del Carmen Rodriguez and Robert Sinden describe a novel method: suppression subtractive hybridization (SSH) and its successful application in obtaining mosquito midgut stage-specific genes of Plasmodium.

Molecular analysis of lineage-specific chimerism and minimal residual disease by RT-PCR of p210(BCR-ABL) and p190(BCR-ABL) after allogeneic bone marrow transplantation for chronic myeloid leukemia: increasing mixed myeloid chimerism and p190(BCR-ABL) detection precede cytogenetic relapse

We studied lineage-specific chimerism and minimal residual disease (MRD) in sequential posttransplant samples from 55 patients who underwent unmanipulated (n = 44) or partially T-cell-depleted (n = 11) allogeneic bone marrow transplantation (BMT) for chronic myeloid leukemia (CML). Chimerism was assessed by polymerase chain reaction (VNTR [variable number of tandem repeats]-PCR) analysis in highly purified CD19+, CD3+, CD15+, and CD56+ cell fractions, whereas MRD was investigated in whole blood by reverse transcriptase-PCR (RT-PCR) of both p210(BCR-ABL) and p190(BCR-ABL) hybrid transcripts. Of 55 patients, 14 (including 6 T-cell-depleted patients) had cytogenetic relapse at 5-80 months and progressed to hematologic relapse, while 41 patients remained in prolonged cytogenetic remission 12-107 months post-BMT. Before leukemia recurrence, patients in the relapse group showed a consistent evolution pattern sequentially featured by persistent p210(BCR-ABL) positivity, increasing mixed chimerism (MC) in myeloid cells, p190(BCR-ABL) positivity, and, finally, cytogenetic relapse. Myeloid MC preceded cytogenetic relapse by 2-12 months, whereas p190(BCR/ABL) was detected 1-6 months prior to cytogenetic relapse in 11 patients and concomitant with cytogenetic relapse in 3 patients. In the remission group, all patients invariably tested negative for p190(BCR-ABL); 10 patients tested positive for p210(BCR-ABL) at variable time-points but showed persistent full donor chimerism (DC), whereas 31 patients tested p210(BCR-ABL) negative and displayed full DC or transient MC due to the persistence of recipient T cells. Two patients in the relapse group were successfully reinduced into molecular remission with donor lymphocyte infusion. Sequential molecular analysis after such treatment showed the inverse pattern to that observed prior to relapse, ie, progressive disappearance of p190(BCR-ABL) transcripts, conversion of myeloid chimerism to donor type, and, finally, p210(BCR-ABL) negativity. We conclude that lineage-specific chimerism and p190(BCR-ABL) messenger RNA (mRNA) analyses contribute a better characterization of CML evolution after BMT and enable early identification of patients at the highest risk of relapse. (Blood. 2000;95:2659-2665)

Stereotactic targeting of the globus pallidus internus in Parkinson's disease: imaging versus electrophysiological mapping

OBJECTIVE

The reintroduction of pallidotomy for the treatment of Parkinson's disease (PD) has generated various opinions regarding the ideal anatomic or physiological location of the target within the globus pallidus. The role of microelectrode recording guidance in pallidotomy for the treatment of advanced PD is presently under debate. The purpose of this study was twofold. The first goal was to determine the degree of accuracy in the targeting of the globus pallidus internus (GPi) with magnetic resonance imaging (MRI), by comparing these results with the final placement of the thermolytic lesions (as defined by electrophysiological assessment). The second goal was to ascertain the somatotopic arrangement of the GPi in PD.

METHODS

The analysis involved 50 patients with PD who underwent microrecording-guided pallidotomy. The theoretical coordinates for lesioning were calculated after definition of the intercommissural line by MRI. The actual placement of the lesions was determined after mapping of the GPi by microrecording, using stimulation to identify the sensorimotor region and its somatotopic organization.

RESULTS

In most cases, the lesions were placed posterior and lateral to the targets chosen by MRI. Mapping by microrecording revealed differences of 2.3 +/- 1.55 mm and 3 +/- 1.9 mm in the mediolateral and anteroposterior coordinates, respectively. The actual lesion overlapped the theoretical target for only 45% of the patients. The somatotopic organization of the GPi was analyzed. Most of the units with sensorimotor activity or tremor-related activity were in the lateral portion of the nucleus. Upper limb and axial units were in the most lateral region and mainly in the ventral one-third of the nucleus. Lower limb responses were recorded mainly in the dorsal one-third of the nucleus. Tremor-related cells were found throughout the sensorimotor region of the nucleus.

CONCLUSION

These results indicate that lesion targeting based on MRI alone is not sufficiently accurate to guarantee placement of the lesion in the sensorimotor region of the GPi.

Increasing mixed haematopoietic chimaerism after BMT with total depletion of CD4+ and partial depletion of CD8+ lymphocytes is associated with a higher incidence of relapse

In this study we analysed the incidence and clinical impact of the persistence of host haemopoiesis (mixed chimaerism, MC) after allogeneic BMT in 35 consecutive patients with haematologic malignancies using a total CD4+ cell-depleted graft with an adjusted dose of CD8+ cells (1x10(8)/kg). Chimaerism was assessed by PCR amplification of VNTRs in 30 evaluable patients: 19 non-CML and 11 CML cases which were also evaluated for the BCR-ABL transcript by RT-PCR. All but one had complete engraftment with a donor profile early post-BMT. At the end of the study period, 12 of 30 patients displayed MC (40%). The overall disease-free survival for MC patients was clearly unfavourable when compared to those who exhibited a donor profile (24.7% vs. 100%, P = 0.005). However, we found that only two of five patients with MC in the non-CML group relapsed, whereas a clear correlation could be made between MC and relapse in CML (seven showed MC, preceding cytogenetic or haematological relapse in six of them, which displayed a prior BCR-ABL mRNA positivity). In addition, a quantitative-PCR approach enabled us to demonstrate that increasing amounts of MC are invariably associated with subsequent relapse, whereas a low stable level of host or complete donor haemopoiesis is consistent with clinical complete remission. Although these results suggest that the clinical impact of MC may depend on the underlying disease, it is compatible with the concept that the graft-versus-leukaemia effect against CML is mainly exerted by donor CD4+ lymphocytes. Elimination of this cellular subset may be responsible for the inability of the graft to prevent a progressive increase in the tumor cell burden.

The biosynthesis and post-translational modification of Pbs21 an ookinete-surface protein of Plasmodium berghei

Radiolabelled methionine incorporation into synchronised Plasmodium berghei gametocytes or ookinete cultures, showed that Pbs21 is not synthesised in bloodstage parasites; synthesis was detected within three hours of induction of gametogenesis; synthesis was triggered at gametogenesis, not by fertilisation. We show native Pbs21 to be a hydrophobic membrane protein that was insensitive to cleavage by phosphatidylinositol phospholipase C (PI-PLC), but sensitive to alkaline hydroxylamine, and partially sensitive to glycosylphosphatidylinositol-dependent phospholipase D (GPI-PLD) and HNO2. 3H-myristic and palmitic acid, 3H-glucosamine and mannose incorporation indicated Pbs21 was acylated and glycosylated. Linkage of the acyl group was sensitive to HNO2, which released an acyl-phosphatidylinositol more hydrophobic than that released from P3 of Trypanosoma brucei. All these properties are consistent with the presence of a malaria-specific glycosylphosphatidylinositol (GPI) anchor. In contrast recombinant Pbs21 (rPbs21), expressed in Spodoptera frugiperda cells, was sensitive to both PI-PLC and GPI-PLD, consistent with the protein being modified by a different (S. frugiperda) GPI anchor. Brefeldin A blocked secretion of rPbs21 within a cytoplasmic reticular compartment. Following deletion of the putative GPI anchor addition site (amino acids 189 213), the protein was transported to the cell surface and secreted directly into the aqueous phase of the culture medium. Deletion of amino acids 205-213 disrupted Pbs21 processing, transport through the ER and distribution onto the cell surface. Deletion of amino acids 1-28 prevented transport of Pbs21 into the ER. This suggests that correct processing of the GPI anchor in the ER-Golgi network is essential for the successful secretion of the recombinant protein, which is additionally dependent upon an N-terminal secretory signal sequence.

Neutral polysaccharide from Cedrela tubiflora with anticomplementary activity

A water-soluble polysaccharide extracted from leaves of the Meliaceae Cedrela tubiflora was separated into neutral and acidic polysaccharide fractions. The best anticomplementary activity was exhibited by the neutral product which was further purified by means of gelpermeation chromatography. The composition and methylation analysis of the purified product were determined.

The subthalamic nucleus and tremor in Parkinson's disease

The role of the subthalamic nucleus (STN) in the origin of parkinsonian tremor is discussed. Previous studies in monkeys made parkinsonian by MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) administration suggested a direct participation of the STN in the pathophysiology of tremor. We recorded tremor-related activity in the STN in 12 patients with Parkinson's disease (PD) and found that microstimulation of the sensorimotor region of the nucleus, where these neurons are present, stopped the tremor with a very short latency. Long-term treatment by means of bilateral deep-brain stimulation (DBS) in the same 12 patients led to a significant reduction of tremor as well as other cardinal features of PD. This effect was blindly assessed at 3 months after implantation. In another group of seven patients, a unilateral lesion of the STN was performed. Both postural and resting tremor were significantly improved on the limbs contralateral to the lesion side. In three patients, tremor disappeared completely after 12 months of follow up. The electrophysiologic data and therapeutic effect of inactivating the STN strongly indicated that this structure is directly involved in the origin of parkinsonian tremor, as suggested by the MPTP model.

First isolation of Cryptococcus neoformans var. gattii, serotype C, from the environment in Colombia

The natural habitat of Cryptococcus neoformans var. gattii, serotype B in the environment was established by Australian investigators who demonstrated its association with species of Eucalyptus. The aim of the present study was to search for the habitat of this variety in a city of Colombia, where clinical cases due to this variety occur with great frequency. For a period of 5 months detritus, vegetable material and air samples in and around 68 almond trees (Terminalia catappa) located in the city were studied. C. neoformans var. gattii serotype C was the only variety isolated from two of the 68 trees sampled. These trees were positive for 4 of the 5 months during which they were studied. From the first positive sample kept under refrigeration, it was possible to isolate the fungus up to 3 months later. This is the first report of the isolation of serotype C from the environment. More studies are required in order to establish the ecological significance of this finding.

Subthalamic nucleus-mediated excitotoxicity in Parkinson's disease: a target for neuroprotection

Dopamine deficiency causes disinhibition and overactivity of the subthalamic nucleus (STN). Output neurons from the STN are excitatory and use glutamate as a neurotransmitter. They project to the external and internal segments of the globus pallidum (GPe and GPi), the substantia nigra pars reticulata (SNr), and the pedunculopontine nucleus (PPN). In addition, STN neurons provide excitatory innervation to dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc) that contain glutamate receptors. Stimulation of the STN induces bursting activity in SNc dopaminergic neurons. This raises the possibility that the disinhibition of STN neurons that occurs as a result of a dopamine lesion might induce excitotoxic damage in target structures, including the SNc. In addition, the reduction in complex I activity found in the nigra in Parkinson's disease (PD) may cause mitochondrial dysfunction and make SNc dopaminergic neurons vulnerable to even physiologic concentrations of glutamate. We postulate that the dopamine loss that occurs in PD produces augmented STN activity which, in turn, causes further damage to vulnerable dopaminergic neurons, thereby creating a scenario for an increasing cycle of neuronal loss in the SNc. In addition, STN overactivity could, in theory, cause damage to the GPi, SNr, and PPN and thereby account for the development of parkinsonian features that do not respond to levodopa in patients with advanced disease. This hypothesis suggests that pharmacologic or surgical therapies that reduce STN neuronal overactivity or block glutamate receptors in the SNc and other target structures might be neuroprotective and might slow or halt the progression of neurodegeneration in PD.

Fatty acid composition of erythrocyte membranes affects iron absorption in rats

We studied the influence of the fatty acid composition of three different diets on iron absorption in relation to the lipid peroxidation of the erythrocyte membranes. After weaning, three groups of rats were fed isoenergetic semipurified diets for 16 wk: control diet (containing canola oil and peanut oil), tripalmitin diet (a saturated fatty acid diet) and a sardine oil diet rich in polyunsaturated fatty acids. Eight rats from each group were administered 59FeSO4 by gastric intubation for ferrokinetic studies, and six rats from each group were used for several analyses in blood, liver, spleen and erythrocytes. Results obtained from 59Fe eliminated in feces and 59Fe present in plasma, both calculated by the area under the curve and from maximum concentration in plasma, indicated that the sardine oil diet induced higher iron absorption than the control diet. The lipid peroxidation of erythrocyte membranes in rats fed sardine oil was higher than that in control rats due to high membrane's (n-3) polyunsaturated fatty acid content and low alpha-tocopherol level. The 59Fe in liver and spleen of rats fed the sardine oil diet was higher than in rats fed the control diet, and 59Fe was diverted to erythrocytes to a greater extent than in rats fed the control diet due to their reduced life-span. The sardine oil diet, by lessening alpha-tocopherol and raising the degree of lipid peroxidation in erythrocytes, augments iron absorption, whereas the tripalmitin diet, by protecting erythrocyte membranes from lipid peroxidation, leads to a lower rate of iron absorption.

Thawing and processing of cryopreserved bovine spermatozoa at various temperatures and their effects on sperm viability, osmotic shock and sperm membrane functional integrity

The objective of this study was to evaluate the effects of thawing and processing temperatures on post-thaw sperm viability, occurrence of osmotic shock and sperm membrane functional status. The occurrence of osmotic shock, characterized by increased spermatozoa with coiled tails, eventually results in reduced sperm viability and sperm membrane integrity. The effects of different thawing temperatures were assessed by thawing frozen specimens at 37, 21 or 5 degrees C for 1 to 2-min, followed by processing at these temperatures. A subset of frozen specimens were thawed at 37 degrees C for 10 to 15-sec and transferred to a water bath at 21 or 5 degrees C for 1 to 2-min to complete thawing, followed by processing at these temperatures. Sperm processing (washing) consisted of dilution, centrifugation and resuspension to remove glycerol from the medium and to gradually return the spermatozoa to isotonic conditions. Post-thawed specimens (0.5 mL) were slowly diluted 1:1 (v/v) at a rate of 0.1 mL/min, centrifuged, and resuspended to 0.5 mL (37 degrees C). Diluted specimens were equilibrated for 1 to 2-min after dilution and for 5-min after resuspension. The specimens were then incubated for 2-h (37 degrees C) and assessed at 60-min intervals for the percentage of motility, for progressive motility (Grades 0 to 4), for the percentage of spermatozoa with coiled tails, and for the percentage of swollen spermatozoa. The percentage of swollen spermatozoa (measurement of sperm membrane integrity) was assessed by exposing spermatozoa to a modified hypoosmotic swelling (HOS) test. The results obtained seem to indicate that physiological thawing and processing temperatures (37 degrees C) are required to maintain sperm motility. However, thawing and processing at lower temperatures (< 37 degrees C) seems to prevent the occurrence of osmotic shock and to maintain sperm membrane functional integrity. In this study, thawing at 37 degrees C (10 to 15-sec) and transfer to a water bath at 21 degrees C (1-min) to complete thawing, followed by processing at 21 degrees C, yielded better results in terms of increased sperm viability, reduced occurrence of osmotic shock and higher reactivity to the HOS test.

Effect of a cecropin-like synthetic peptide (Shiva-3) on the sporogonic development of Plasmodium berghei

The effect of a synthetic cecropin-like peptide, Shiva-3, on in vitro ookinete development and on the early sporogonic stages of Plasmodium berghei in the midgut of Anopheles albimanus was investigated. Peptide concentrations of 75 and 100 microM were effective (P < 0.05) in reducing ookinete production and the number of infected mosquitoes in almost all experiments. These peptide concentrations in the midgut were not toxic for the survival of the mosquitoes. Complete inhibition was obtained if 100 microM Shiva-3 was applied in the first 8 hr of parasite development. The deleterious effect of the peptide on the parasite was effective after exposure for as short as 50 sec and the permanence of free peptide in the mosquito midgut was estimated to be of a minimum of 5 min. These observations indicate the possibility of using Shiva-like peptide genes to engineering malaria-resistant vectors as an alternative in malaria control strategies.

The effect of GTP on the aluminum fluoride- and forskolin-activated adenylyl cyclase from human embryonic kidney 293 cells

GTP has been shown to inhibit AlF4(-)-stimulated, and to activate forskolin-stimulated adenylyl cyclase activity in the presence of Mg2+ in cell membranes from human embryonic kidney 293 cells. The maximal inhibitory response of AlF4(-)-stimulated adenylyl cyclase activity by GTP was not dependent on the concentration of Mg2+, but was so in the case of forskolin-activated activity at all forskolin concentrations assayed. Mn2+ ions stimulated AlF4(-)- or forskolin-activated adenylyl cyclase activity to a greater extent than Mg2+. The inhibition of AlF4(-)-stimulated cyclase by GTP was still observed with Mn2+, but the activation of forskolin-stimulated cyclase by GTP was not. When assayed together, Mn2+ and Mg2+ showed non-additive behaviours with respect to the amount of cyclic AMP formed after AlF4(-)-stimulation of adenylyl cyclase. The temperature dependence of the activation of adenylyl cyclase by forskolin, AlF4- or under basal conditions was observed to be somehow different in the presence of Mn2+ than in the presence of Mg2+ ions. Cholera toxin treatment produced a markedly increased cyclase activity, specially when assayed with AlF4-. In the case of forskolin-activated adenylyl cyclase, UTP and CTP were unable to reproduce the cyclase activation detected with GTP. However, in the case of AlF4(-)-stimulated adenylyl cyclase, UTP was as good as GTP at inhibiting cyclase activity, and CTP virtually eliminated the activation of the cyclase with AlF4-.

Bionomics of adult Anopheles pseudopunctipennis (Diptera: Culicidae) in the Tapachula foothills area of southern Mexico

Field studies on the bionomics of adult Anopheles pseudopunctipennis Theobald were conducted to assess its relative importance as a primary vector of vivax malaria in southern Mexico. In four malaria endemic villages in a foothill region near Tapachula, Mexico, population densities of A. pseudopunctipennis increased during the dry seasons of 1990 and 1991. The pattern of nocturnal host-seeking activity indoors was unimodal with a late night peak at 0100 hours enhancing its vectorial significance, because it occurred when most residents were asleep and fully exposed to the anophelines. Comparisons of trapping methods showed that a horse-baited trap was more effective than human landing catches or UV light traps. Pit shelters, on the other hand, were more effective than indoor and natural shelter resting collections. Results of enzyme-linked immunosorbent assays performed on wild-caught A. pseudopunctipennis specimens documented the presence of natural infections with the VK210 and new VK247 circumsporozoite polymorphs of P. vivax. These findings verify the importance of A. pseudopunctipennis as a major vector of vivax malaria at higher elevations and extend the geographical range of the VK247 P. vivax polymorph in Mexico.

Intradomiciliary behavior of Anopheles albimanus on the coastal plain of southern Mexico: implications for malaria control

The postfeeding indoor resting behavior of Anopheles albimanus in experimental houses in southern México was investigated by using a mark-recapture procedure. The majority of mosquitoes rested inside houses after taking a blood meal indoors. There was a higher landing frequency on interior surfaces other than walls and roofs; however, mosquitoes rested for longer periods on these 2 surfaces. Successive landings on walls after short flights showed that mosquitoes gradually increased their mean landing height from 1.0 to 1.4 m. Similarly, mosquitoes resting at the base of inner roofs had a successive landing height range of about 0.5 m. Based on these observations and the potential for reduction of nearly 50% in the quantity of insecticide used and the time needed to apply it, village-scale studies involving the selective spraying of a 1-m-wide swath of insecticide on walls and on roofs are recommended in this area.

Effects of truncations of the cytoplasmic tail of the luteinizing hormone/chorionic gonadotropin receptor on receptor-mediated hormone internalization

The LH/CG receptor is a member of the family of G protein-coupled receptors and consists of a large N-terminal extracellular domain (which is responsible for binding hormone) attached to a region that spans the plasma membrane seven times, ending with an intracellularly located C-terminus. Binding of LH or human CG (hCG) to the LH/CG receptor causes a stimulation of adenylyl cyclase, presumably via activation of Gs. The binding of hormone also leads to its subsequent internalization by receptor-mediated endocytosis. In order to investigate the role of the cytoplasmic tail of this receptor in these events, we prepared a series of mutants in which progressively larger portions of the cytoplasmic tail were deleted. Deletion of 58 amino acids from the C-terminus, in which only 11 cytoplasmic residues remain, resulted in a receptor that was not expressed on the plasma membrane. Receptors rat LHR (rLHR)-t653 and rLHR-t631, in which 21 or 43 amino acids were removed, respectively, were properly expressed. These results suggest that a region(s) between residues 616 and 631 of the rLH/CG receptor are required for proper insertion and/or targeting of the receptor into the plasma membrane. Cells expressing rLHR-t653 or rLHR-t631 bound hCG with the same high affinity as cells expressing the full-length receptor, and basal levels of cAMP were the same among the cells. However, cells expressing the truncated receptors responded to hCG with approximately 2-fold greater levels of maximal cAMP accumulation than cells expressing the full-length receptor. Deletion of up to 43 amino acids from the C-terminus of the rLH/CG receptor had no deleterious effect on hCG internalization. In fact, mutants lacking 21 and 43 amino acids exhibited progressively faster rates of hCG internalization as compared to the full-length receptor. Once internalized, hCG was also degraded at a faster rate in cells expressing the truncated LH/CG receptors. Since hCG-stimulated cAMP stimulation and hCG internalization are retained by rLHR-t631, it can be concluded that the residues, not necessarily the same, required for these functions reside within the 26 amino acids of the cytoplasmic tail closest to the seventh transmembrane helix and/or residues within the intracellular loops. Our data show, however, that both hCG-stimulated cAMP production and hCG internalization are enhanced by the removal of the distal portion of the cytoplasmic tail.

Effects of cocaine on testicular structure in the rat

The effects of hourly injections of moderate doses of cocaine hydrochloride (0.5 and 10 mg/kg body weight) over 5 h on testicular structure and testosterone levels were studied in male Wistar rats. Cocaine produced a rapid disruption of spermatogenesis; the number of normal seminiferous tubules declined to 50% (low dose) and 40% (high dose), and regressive tubules (tubules with cellular degeneration, cell sloughing, or abnormal cell structures) increased to 50% (low dose) and 60% (high dose) after treatment with cocaine. The mean tubular diameter, the surface occupied by the tubules, and the volume of seminiferous tubules per pair of testes were significantly reduced (P less than 0.01) after both doses of cocaine. Cocaine produced ultrastructural changes in the cells of the seminiferous epithelium (spermatogonia, spermatids, and Sertoli cells) including vacuoles, abundant lipid droplets, and giant mitochondria. Lower doses of cocaine increased serum testosterone levels (P less than 0.025) while higher doses did not. These findings indicate an acute effect of cocaine on the structure of the rat testis.

Seroepidemiological survey of hepatitis B infection in a cohort of military recruits in Barcelona, Spain

The prevalence of HBsAg and anti-HBs in a representative sample of 839 recruits from a cohort of 17-18 year-old males living in Barcelona has been determined by radioimmunoassay of eluates of finger-prick dried blood. It was 0.48% for HBsAg, and 3.22% for anti-HBs. All carriers of HBsAg were anti-HBe positive and had normal liver function tests. Half of them had antecedents suggestive of a materno-fetal acquisition of the infection. A relationship between educational level and the risk of infection was also demonstrated.

Regulation of androgen receptor protein and mRNA concentrations by androgens in rat ventral prostate and seminal vesicles and in human hepatoma cells

The effects of androgen withdrawal and replacement on the concentrations of androgen receptor (AR) protein and AR mRNA were investigated in rat ventral prostate and seminal vesicles and in cultured human hepatoma (HepG2) cells. AR mRNA concentrations were determined by Northern blotting with single stranded AR cRNA as the hybridization probe, whereas antibodies raised against two synthetic 17-amino acid long peptides corresponding to the N-terminal and steroid-binding regions of the AR were employed in immunological receptor assays. AR mRNA levels in both prostate and seminal vesicles increased about 2-fold within 24 h after castration and continued to rise within the next 48 h to values that were 9- to 11-fold higher than those in intact controls. Administration of pharmacological doses of testosterone (400 micrograms steroid/day) to 1-day castrated animals for 24-48 h brought about a decrease in AR mRNA levels in accessory sex organs to levels in intact controls. Similar results were obtained in cultured HepG2 cells where a switch to serum- and steroid-free medium elicited a rapid increase (approximately 4-fold in 10 h) in the AR mRNA level, which was prevented by inclusion of 10(-7) M testosterone in culture medium. Similar, but quantitatively less marked, changes occurred in the AR protein concentration in prostate, seminal vesicles, and HepG2 cells, as determined by immunoblotting using antibodies against AR peptides. In addition, immunohistochemical studies showed that AR is a nuclear protein of the prostatic epithelial cells in both intact and castrated rats, and suggested that short term castration increases the concentration of nuclear AR in the prostate. Taken together, these data indicate that androgens down-regulate the concentration of AR protein and AR mRNA in a variety of target tissues.

Initiation of growth in pbpAts and rodAts mutants of Escherichia coli

Escherichia coli strains harbouring pbpAts mutations are particularly sensitive to functional alterations of penicillin-binding protein 2 (PBP 2) at the initiation of growth. Shift-up to 42 degrees C results in the inability of cells to reach a steady rate of growth and division. Furthermore, a very high proportion of cells generate minicell-like structures which are pinched-off through a process requiring the activity of penicillin-binding protein 3 (PBP 3).

The orientation of the lutropin/choriogonadotropin receptor in rat luteal cells as revealed by site-specific antibodies

Polyclonal antibodies were raised against peptides corresponding to specific regions of the rat luteal lutropin/choriogonadotropin (LH/CG) receptor. One of these (anti-LHR02) was directed against a 13 amino acid sequence that occurs within the large N-terminal hydrophilic domain, and another (anti-LHR06) was directed against the 14 most C-terminal amino acids of the receptor (as deduced from the open reading frame of the cDNA). These antisera, which we show to be highly specific for the LH/CG receptor, were used in indirect immunofluorescence experiments with primary cultures of rat luteal cells to determine the orientation of this receptor within the plasma membrane. Anti-LHR02 was shown to specifically bind to intact cells. In contrast, anti-LHR06 did not bind to intact cells. When the cells were first permeabilized with detergent and then incubated with this antibody, however, an intense and specific immunofluorescence was observed. These studies clearly show that the orientation of the LH/CG receptor in the plasma membrane is such that the N-terminal domain is located extracellularly, while the C terminus is located intracellularly. Thus, we have experimentally confirmed that the orientation of this receptor as predicted from the amino acid sequence is indeed correct.

Long day photoperiods and temperature of 20 degrees C induce spermatogenesis in blinded and non-blinded marbled newts during the period of testicular quiescence

Adult male marbled newts (Triturus marmoratus) were collected at the end of the spermatogenesis period and exposed to different photoperiods (natural-daylength-simulated photoperiod, total darkness, 8L:16D, 12L:12D, 16L:8D, and continuous light) for 3 mo. Temperature was maintained at 20 degrees C. Two additional groups of newts were blinded and exposed to either the natural-simulated photoperiod and to 16 h of light per day respectively. Quantitative histologic studies on testicular development and germ cell volume per testis were performed. The newts captured in the field at the beginning (initial controls) or at the end of the experiments (final controls) were in the period of testicular quiescence. Newts kept in total darkness or exposed to a short photoperiod (8L:16D) showed germ cell development up to primary spermatocytes, whereas germ cell development in the newts exposed to long photoperiods (12L:12D or 16L:8D) progressed to elongated spermatids. The newts exposed either to intermediate photoperiods (natural-simulated photoperiod) or to constant light showed an intermediate degree of germ cell development (up to round spermatids). No significant differences between non-blinded and blinded animals were found. These results suggest that (1) mild temperature initiates testicular development in the period of testicular quiescence, (2) long photoperiods associated with mild temperatures produce spermatogenesis in this period, (3) complete darkness or constant light are less effective than some intermediate photoperiod, and (4) the effect of photoperiod on testicular function in newts is not related to ocular photoreception.

Seminiferous tubule involution in elderly men

The observation of different types of seminiferous tubules (from tubules with normal spermatogenesis to sclerosed tubules) in aging human testes points to the progressive stages of tubular involution in elderly men. The tubules with hypospermatogonesis (reduced number of elongated spermatids) show numerous morphological anomalies in the germ cells, including multinucleated cells. Abnormal germ cells degenerate, causing Steroli cell vacuolation. These vacuoles correspond to dilations of the extracellular spaces resulting from the premature exfoliation of germ cells. Degenerating cells that are phagocytized by Sertoli cells lead to an accumulation of lipid droplets in the Sertoli cell cytoplasm. The loss of germ cells begins with spermatids, but progressively affects the preceding germ cell types, and tubules with maturation arrested at the level of spermatocytes or spermatogonia are observed. Simultaneously, an enlargement of the tunica propria occurs. This leads to the formation of sclerosed tubules, some of which display a low seminiferous epithelium consisting of a few cells--including lipid-loaded Sertoli cells and both Ap and Ad spermatogonia--and others, showing complete sclerosis, are devoid of seminiferous epithelium. The development of tubular involution is similar to that reported after experimental ischemia, which also seems to cause nonspecific effects on the testis such as multinucleate cells, vacuoles, and increased lipids in Sertoli cells.

Presence of basic proteins and ribonucleoproteins in the neck region of human spermatids and spermatozoa

The ultrastructural cytochemical study of the neck region of human spermatids and spermatozoa revealed that, besides the centrioles, the basal plate, the lateral cupshaped junction body and the annulus material showed affinity for both ethylene diamine tetra-acetic acid (EDTA) stain (a preferential staining method for ribonucleoproteins) and ethanolic phosphotungstic acid (PTA) stain (for cellular localisation of basic proteins). The capitulum and the surface of the striated columns were also stained with ethanolic PTA. The chromatoid body and annulate lamellae-which were frequently encountered in the neck region--stained with both EDTA and ethanolic PTA techniques. This suggests a possible participation of the chromatoid body and annulate lamellae in the formation of the neck region structures.

Presence of ribonucleoproteins and basic proteins in the nuage and intermitochondrial bars of human spermatogonia

Ultrastructural cytochemical study of the nuage in the human adult testis revealed that this structure was a cytoplasmic fine fibrillar electron-dense mass, similar to the chromatoid body of spermatids, in all spermatogonial types and spermatocytes. The nuage was often observed in relation with the nucleus or mitochondria. Cytochemical techniques showed staining affinity of the nuage for both ethanolic phosphotungstic acid and ethylene diamine tetra-acetic acid. The intermitochondrial bars were also stained with the two procedures. The results suggest that the nuage originates from the nucleus and migrates to the cytoplasm through nuclear pores, giving rise to the intermitochondrial bars.

Experimental comparison of methods for simultaneous selection of two correlated traits in Tribolium : 1. Empirical and theoretical selection indexes

Two lines of Tribolium castaneum were selected in each of three replicates for egg laying between 7 and 11 days after adult emergency and for adult weight at 12 days, using theoretical (IT) and empirical (IP) index selection methods. Index coefficients were given empirically in the IP line and they were adjusted in the successive generations of selection according to the results obtained in the previous ones. Highly repeatable selection responses in all replicates occurred in both lines for the aggregate genotype (egg laying plus adult weight) and for each individual trait. The IP line tended to increase slightly more than the IT line for aggregate genotype and egg laying, while the highest response in adult weight was obtained with the IT method. The two methods gave consistently different responses in each replicate. The expected results were that IT selection should not exceed IP selection for the aggregate genotype and egg laying while theoretically the IT method should have been superior for increase adult weight. Theoretical expectations for adult weight have been fulfilled in practice. The IP method would be preferred in a practical sense because of its simplicity and freedom from need of parameter estimation.

A simple and reproducible method to evaluate granulocyte adherence

A simple method was devised to measure granulocyte adherence in whole blood. Columns of glass beads (4.5 mm diameter) in disposable plastic syringes were used. The assay showed great reproducibility when done in triplicate, the day to day variations in a given individual being minimal. Previous incubation of the blood with different ethanol concentrations diminished granulocyte adherence. The assay is easy to perform and does not require special equipment.