Organization of the cis-acting element required for wheat dwarf geminivirus DNA replication and visualization of a rep protein-DNA complex

Initiation of geminivirus DNA replication depends on the activity of the initiator protein (Rep) upon interaction with DNA sequences present in the intergenic region of the viral DNA. In this study, we have analyzed the DNA sequences present in the large intergenic region (LIR) of wheat dwarf virus (WDV), a subgroup I member of the geminivirus family, which are required for viral DNA replication. We have (i) defined the boundaries of the viral cis-acting DNA replication element, (ii) determined the contribution of different domains of the LIR to DNA replication efficiency, and (iii) visualized WDV Rep-DNA complexes. Analysis of unidirectional deletions from both sides of the LIR leads us to establish that a approximately 200-bp cis-acting element (core) is essential for viral DNA replication. It spans approximately 170 and 28 bp upstream and downstream, respectively, from the initiation site (+1), located in the invariant loop. This core element is flanked, at each side, by auxiliary regions (5'-aux and 3'-aux, approximately 70 and approximately 25 bp long, respectively), which contain DNA sequences that stimulate DNA replication. Competition experiments using viral replicating vectors bearing wild-type or mutant WDV LIRs suggest that the auxiliary regions may contribute to the stabilization and/or activity of the initiation complex formed by WDV Rep at the origin. We have visualized DNA-protein complexes by electron microscopy and a high-affinity binding site of WDV Rep protein within the core element has been mapped to approximately 144 +/- 18 bp upstream from the initiation site, between the start site for complementary-sense transcription and the TATA box. Our studies (i) establish the modular structure of the WDV DNA replication cis-acting element and (ii) provide direct evidence for the formation in vitro of a large nucleoprotein complex within the essential cis-acting element.

Antifeedant Delphinium Diterpenoid Alkaloids. Structure-Activity Relationships

The insect antifeedant and toxic activity of the Delphinium diterpene alkaloids 15-acetylcardiopetamine, cardiopetamine along with its amino alcohol, the beta,gamma unsaturated ketone, and the acetylated ketone derivatives were studied in Spodoptera littoralis and Leptinotarsadecemlineata. Cardiopetamine and 15-acetylcardiopetamine strongly inhibited the feeding activity of S. littoralis and L. decemlineata, respectively. Structure-activity studies with S. littoralis showed that the C13 and C15 hydroxy substituents are essential features of the active molecule, while a C13 hydroxy and/or a C15 acetate determined their effect on L.decemlineata. The C11 benzoate group enhanced the biological effect on both insect species. These alkaloids were not toxic to S. littoralis, while their toxicity on L. decemlineata was inversely correlated with their antifeedant effects, the beta,gamma unsaturated ketone derivative being the most toxic. Cardiopetamine showed little antifungal action against several species of plant pathogens and did not have any mutagenic effects on Salmonella typhimurium by means of the Ames test.

Influence of chronic alcohol abuse and liver disease on hepatic aldehyde dehydrogenase activity

Alcohol metabolism results in the production of acetaldehyde, a compound that is much more toxic than ethanol itself. Hepatic aldehyde dehydrogenase (ALDH) is the main enzymatic system responsible for acetaldehyde clearance from the hepatocyte. The objective of this study was to determine the modifications in ALDH activity due to chronic alcohol abuse and liver disease. ALDH activity was determined in samples of liver tissue from 69 alcoholic and 82 nonalcoholic subjects, with and without liver disease. According to the results of liver pathology examination, alcoholic patients were classified into the following groups: controls, with no liver disease (group 1), noncirrhotic liver disease patients (group 2), and cirrhotics (group 3). Nonalcoholic subjects were categorized, using the same criteria, into groups 4, 5, and 6, respectively. ALDH activity was determined spectrophotometrically at two substrate concentrations: 18 mM for total activity and 180 microM for low Km activity. High Km activity was calculated by subtracting the low Km activity value from that of total ALDH activity. Results obtained in each group were expressed as the mean +/- SD of mU of g of wet weight. There were no significant differences when the total ALDH activity from the alcoholic and the nonalcoholic patients with a similar degree of liver pathology were compared: group 1, 1257 +/- 587 vs. group 4, 1328.1 +/- 546.2 (p: NS); group 2, 919.1 +/- 452.4 vs. group 5, 753.5 +/- 412 (p: NS); and group 3, 430.2 +/- 162.4 vs. group 6, 473.2 +/- 225.3 (p: NS). On the other hand, total ALDH activity was significantly lower in cirrhotics than in controls, both among alcoholics (p < 0.01) and among nondrinkers (p < 0.05). The low Km activity was severely reduced in cirrhotics, both alcoholics and nonalcoholics (p < 0.01). High Km activities in cirrhotic patients were low, compared to controls, both in alcoholics and nonalcoholics, although the difference was nonsignificant. The results of the present study suggests that chronic alcohol abuse does not depress ALDH activity. A reduction in the ALDH activity detected in patients with severe liver disease (cirrhotics) was clearly a consequence of liver damage. This reduction was due mainly to a decrease of the low Km ALDH activity, but a trend to a decrease in the high Km ALDH activity was also detected.

Cyclosporine-induced retinal toxic blindness

We report the case of a BMT recipient who developed blindness 22 months after BMT. Microvascular retinopathy, cortical blindness and other ocular pathologies were excluded with appropriate tests. Electrophysiological studies showed retinal damage without excluding an optic nerve lesion. The patient, who had several risk factors for neurologic-induced cyclosporine toxicity, improved with cyclosporine withdrawal. Our findings stress the need of electrophysiological tests to exclude neuroretinal damage in patients receiving cyclosporine after BMT.

Angiotensin I-converting enzyme and angiotensinogen gene polymorphisms in non-insulin-dependent diabetes mellitus. Lack of relationship with diabetic nephropathy and retinopathy in a Caucasian Mediterranean population

Genotypic abnormalities of the renin-angiotensin system have been suggested as a risk factor for the development of microangiopathic complications in diabetic patients. We studied the relationship of either an insertion-deletion polymorphism in the angiotensin-converting enzyme (ACE) gene and the M235T and T174M variant polymorphisms of the angiotensinogen (AGT) gene in non-insulin-dependent diabetes mellitus (NIDDM) patients and its relationship with cardiovascular complications. A total of 193 NIDDM patients (89 men and 104 women aged 59.2 +/- 10.0 years; diabetes duration, 13.2 +/- 6.2 years) and 90 control subjects (42 men and 48 women aged 45.4 +/- 12.6 years) were recruited for the association study. Distribution of the genotype or allelic frequencies for all the studied polymorphisms did not differ significantly between controls and NIDDM patients. ACE and AGT genes did not display any difference in clinical or metabolic parameters according to each gene's genotype for either the control or the NIDDM group. For evaluation of nephropathy and retinopathy, NIDDM patients were matched with subjects not having microangiopathic complications. Thus, a total of 60 patients had diabetic nephropathy and were compared with 100 patients with normoalbuminuria. Sixty-eight NIDDM patients had diabetic retinopathy, and 92 patients presented no signs of retinopathy. There were no differences in genotypic or allelic distribution between NIDDM patients for either the presence or absence of retinopathy or nephropathy. We conclude that the ACE and AGT polymorphisms do not contribute to the genetic susceptibility to diabetic nephropathy and retinopathy in a caucasian Mediterranean population.

[Our experience in portal cavernomatosis in childhood: cross-sectional study and analysis of results]

A retrospective and transversal study of our patients with portal cavernomatosis is developed, with the aim of comparing the evolution and the present status of the patients that have undergone different therapeutical approaches. Between 1975 and 1995, 15 patients with portal cavernomatosis have been treated. Personal history, signs and symptoms at the moment of diagnosis, and treatment were analyzed. Now, the controls have been made by physical examination and ECO-Doppler of the espleno-portal system. In 6 cases the absence of bleeding made surgery unnecessary. In the 9 patients with digestive haemorrhage, it could be controlled pharmacologically, with a later surgical approach. Now, all non-operated and 6 operated patients show splenomegaly, without bleeding. The ECO-Doppler shows colateral flow, the splenomegaly in the non-operated and the surgical shunts and the hepatofugal circulation in the operated patients. Looking at our results, we believe that prophylactic surgery is not indicated. In those cases of digestive bleeding, surgery after the complete resolution of the acute disease shows good results at a short and long term.

Opportunistic infections in pediatric HIV infection: a study of 74 autopsy cases from Latin America. The Latin American AIDS Pathology Study Group

The present report describes opportunistic infections found at 74 autopsies of pediatric HIV/AIDS patients performed at several hospitals in Latin American countries. Fungal infections were the most common (53 cases), Candida sp. (39.18%) and Pneumocystis carinii (20.27%) being the most frequently recognized. Other fungal diseases included histoplasmosis, aspergillosis, and cryptococcosis. Viral infections were present in 31 cases, 38.7% being due to cytomegalovirus. Other viruses recognized included herpes simplex and adenovirus. Additional opportunistic infections were due to Mycobacterium avium-intracellulare, toxoplasmosis, and tuberculosis. Nonspecific bacterial bronchopneumonia was present in 11 cases. Cytomegalovirus and P. carinii coinfection was the most common association found. In this series patients died at a younger age (72% at or younger than 1 year old) and there was a slightly higher number of cases of histoplasmosis and brain toxoplasmosis than in other previously published series of infants and children.

Immunological and virological activity of zalcitabine and zidovudine in combination in HIV-positive people with CD4 cell counts of between 200-500 cells/mm3

We evaluated the effect of combination therapy with zidovudine (AZT) plus zalcitabine (ddC) in human immunodeficiency virus type 1 (HIV-1)-infected patients who had not previously received antiretroviral treatment ('naive' patients). The immunological and virological parameters evaluated were CD4 cell count, syncytium-inducing (SI) viral phenotype and plasma HIV-1 RNA copies/ml (HIV viral load). A total of 75 patients entered the study, with CD4 cell counts between 200 and 500 cells/mm3. All received zidovudine (200 mg) plus zalcitabine (0.75 mg) three times daily for 24 weeks. Treatment was well tolerated. However, four patients presented with anaemia (haemoglobin < 10.0 g/dl) and one patient had both anaemia and neutropenia (0.8 x 10(9) neutrophils/l). Combination therapy with zidovudine plus zalcitabine resulted in a pronounced improvement of virological and immunological markers. Approximately 25% of patients achieved undetectable plasma HIV RNA levels (< 200 copies/ml) at week 24. At the end of the study (24 weeks) a significant reduction (> 0.5 log) of plasma HIV RNA was observed in approximately 70% of patients and in 50% an even greater decrease (> 1 log) was achieved. The most significant decrease in mean plasma HIV RNA levels was observed at week 4, whereas the highest increase in CD4 cell count was found at week 24. Approximately 80% of patients who showed baseline plasma HIV RNA levels below 20000 copies/ml had less than 5000 copies/ml at week 24. The plasma HIV RNA reduction observed at week 4 was significantly maintained at week 24. Therefore, we can rapidly select those who will not respond to therapy and adjust the treatment after a short interval. Our study supports the idea of early therapy because all patients who reached undetectable levels of plasma HIV RNA at week 24 had at baseline a median plasma HIV RNA load of 2560 copies/ml. In conclusion, zidovudine in combination with zalcitabine was well tolerated in the majority of patients and led to a significant reduction in plasma HIV RNA copies in most of the patients with initial viraemia lower than 20000 copies/ml.

Congenital intrahepatic portocaval shunt associated with trimethylaminuria

A case of congenital portal-systemic shunting due to an intrahepatic connection diagnosed by ultrasound scanning and color Doppler in an 8-month-old girl is reported. She began to manifest trimethylaminuria 3 years later. At 7 years of age, she is asymptomatic without therapeutic measures except for diet. This is the seventh reported case and the third in a child to our knowledge.

DNA replication of wheat dwarf geminivirus vectors: effects of origin structure and size

Wheat dwarf virus (WDV) is a representative member of subgroup I of the Geminiviridae, a unique plant DNA virus family. Since geminivirus DNA replication occurs in the host cell nucleus exclusively via double-stranded DNA intermediates, a considerable interest has arisen to use them as expression vectors. We have used particle bombardment to introduce WDV vectors into cultured wheat cells and to analyze the fate of input DNA and the accumulation of newly replicated DNA. Under our conditions, we have found that input DNA, which can be detected immediately after DNA delivery, is rapidly degraded. Newly replicated viral DNA appears approximately 1 day after DNA delivery and reaches a maximum at Days 2-4. Afterward, the total amount of viral DNA is maintained for several days. We have observed a progressive decrease in the relative amount of supercoiled DNA and, concomitantly, an increase in plasmid forms migrating as open circular and nicked DNA. GUS expression from the virion-sense WDV promoter is also maximal 2-3 days after DNA delivery and then it declines to negligible levels 8 days afterward. These results support the conclusion that, under these conditions, reporter gene expression depends on the accumulation of newly replicated, supercoiled plasmid DNA and not on input plasmid DNA. We have also analyzed the effects of WDV origin structure and plasmid size on the accumulation of newly replicated plasmid DNA. Our results lead us to conclude that the replication efficiency of WDV-derived plasmids depends largely on plasmid size. Interestingly, sequences downstream of the initiation site, which in WDV confer an intrinsic curvature to the large intergenic region, seem to have a small effect on the efficiency of plasmid accumulation.

Structural features of phi29 single-stranded DNA-binding protein. II. Global conformation of phi29 single-stranded DNA-binding protein and the effects of complex formation on the protein and the single-stranded DNA

The strand-displacement mechanism of Bacillus subtilis phage phi29 DNA replication occurs through replicative intermediates with high amounts of single-stranded DNA (ssDNA). These ssDNA must be covered by the viral ssDNA-binding protein, phi29 SSB, to be replicated in vivo. To understand the characteristics of phi29 SSB-ssDNA complex that could explain the requirement of phi29 SSB, we have (i) determined the hydrodynamic behavior of phi29 SSB in solution and (ii) monitored the effect of complex formation on phi29 SSB and ssDNA secondary structure. Based on its translational frictional coefficient (3.5 +/- 0.1) x 10(8) gs(-1), and its rotational correlation time, 7.0 +/- 0.5 ns, phi29 SSB was modeled as a nearly spherical ellipsoid of revolution. The axial ratio (p = a/b) could range from 0.8 to 1.0 (oblate model, a < b) or 1.0 to 3.2 (prolate model, a > b). Far-UV CD spectra, indicated that phi29 SSB is highly organized within a wide range of temperatures (15 to 50 degrees C), being mainly constituted by beta-sheet elements (approximately 50%, at pH 7). Complex formation with ssDNA, although inducing minimal changes on the global conformation of phi29 SSB, had a clear stabilizing effect against pH and temperature increase of the solution samples. On the other hand, phi29 SSB binding leads to non-conservative changes of the near-UV CD spectra of ssDNA, which are consistent with different nearest-neighbor interactions of the nucleotide bases upon complex formation. The above results will be compared to those reported for other SSBs and discussed in terms of the functional roles of phi29 SSB.

[The prolapse of the rectum. Treatment with fibrin adhesive]

Injection of sclerosing solutions into the rectal submucosa or into the perirectal space is one of the many therapies designed to correct rectal prolapse. Since 1994, four patients affected with this condition have been treated with fibrin adhesive percutaneous injection. Up to now, this product had not been used to this aim. Age range was from 1 month to 8 years. The medium duration of prolapse prior to therapy was 19 months and three of them had an associated pathology (myelomeningocele, cystic fibrosis and severe psychomotor retardation). There were no post-injection complications. In one patient with an irreducible prolapse an anus encirclement with a rectal tube was associated. Except for this patient, the whole process take less than 24 hours. With a medium follow up of 11 months this therapy has resulted effective in three of our four patients. It has failed in a girl with severe psychomotor retardation.

[Apolipoprotein AI-CIII, B, and CII gene polymorphisms in patients with non-insulin dependent diabetes mellitus. Association with hyperlipemia]

BACKGROUND

Dislipidaemia is an usual feature in patients affected by non insulin dependent diabetes mellitus. Several studies show that this disease could be genetically determined. The aim of this study was to ascertain whether any of the genetic polymorphism remaining in three apolipoprotein loci (apolipoprotein AI-CIII, B100 and CII) is related with the presence of dislipidaemia in non insulin dependent diabetes mellitus patients.

PATIENTS AND METHODS

53 non insulin dependent diabetes mellitus patients with less than 5 years evolution and treated only with diet, were included. 86 healthy persons were included as the control group. The lipidic parameters analyzed were: cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, apolipoprotein AI, B and lipoprotein (a). The following polymorphic variants were analyzed: RFLP-Sacl of the apolipoprotein AI-CIII-AIV cluster, RFLP-Xbal of the apolipoprotein B100 region and the RFLP-Taql of the apolipoprotein E-CI-CII cluster.

RESULTS

There were no genetic nor allelic differences in the distribution of the genes, between controls and diabetic patients. Regarding the apolipoprotein CII gen, the diabetic patients with the T2T2 genotype had higher triglyceride levels (p < 0.01) compared with the remaining genotypes and compared with the control group having the same genotype (p < 0.01) matched for sex, age and body mass index. There was no difference in the metabolic parameters' distribution related to the genotypic distribution of the apolipoproteins AI-CIII and B100 genes.

CONCLUSIONS

The apolipoprotein CII can be related with the presence of hypertriglyceridaemia in non insulin dependent diabetes mellitus patients.

[Treatment with Ethibloc of lymphangiomas and venous angiomas]

Lymphangioma and venous angioma are a group of pathological entities which have required surgical treatment since years. Extension, localization and poor delimitation of some lesions have resulted in technical difficulties and serious complications. Our group began the sclerosing therapy with an injection of fibrin adhesive and, due to the lack of response in the first patient, a program with Ethibloc as an alternative substance was developed. We present 10 cases, 4 lymphangiomas and 6 venous angiomas. In 50% of our patients one single session of sclerotherapy was made, in 25% two sessions, and in the rest 25% three. From 10 cases, 4 are still on treatment, complete remission in 5 cases, and good evolution in one case (mixed lymphangioma). As a long-term complication, we have noticed fistulization in 3 cases, and expulsion of the sclerosing agent. In our experience, percutaneous sclerosis with Ethibloc should be the first therapeutic alternative.

Seroprevalence of Toxocara infection in middle-class and disadvantaged children in northern Spain (Gipuzkoa, Basque Country)

The prevalence of human toxocarosis in disadvantaged socioeconomic population in Europe is unknown. In Gipuzkoa the seroprevalence in middle-class children 2- to 5-years-old, and 6- to 16-year-olds, was zero (n = 135) and 4.4% (n = 320), respectively. In contrast, among socially and economically disadvantaged children the figures were 37% (n = 27) and 65.7% (n = 64). This high prevalence obliges us to consider toxocarosis as a public health problem.

[Prenatal diagnosis of biliary atresia associated with choledochal cyst]

We report a case of biliary atresia promptly detected by its association with a choledochal cyst, prenatally diagnosed at 20 weeks' gestation. The baby was operated at 14 days of life. A choledochal cyst was found and fibrosis of the extrahepatic bile ducts was also noted. So, excision of the choledochal cyst and a Roux-en-Y porto-jejunostomy was done. Nine months later, despite an appropriate biliary drainage, echographic and histological changes compatible with liver cirrhosis have been detected. Including this one, six cases have been reported.

Plant cells contain a novel member of the retinoblastoma family of growth regulatory proteins

The product of the retinoblastoma susceptibility gene (Rb) controls the passage of mammalian cells through G1 phase. Animal virus oncoproteins interact with the Rb protein via an LXCXE motif and disrupt Rb-E2F complexes, driving cells into S-phase. Recently, we found that the RepA protein of a plant geminivirus contains an LXCXE motif that is essential for its function, a finding that predicts the existence of Rb-related proteins in plant cells. Here we report the isolation of a maize cDNA clone encoding a protein (ZmRb1) which, based on structural and functional studies, is closely related to the mammalian Rb family of growth regulatory proteins. ZmRb1 shows a high degree of amino acid conservation when compared with animal Rb members, particularly in the A/B 'pocket' domain, but ZmRb1 has a shorter N-terminal domain. ZmRb1 forms stable complexes with plant LXCXE-containing proteins, e.g. geminivirus RepA protein. Geminivirus DNA replication is reduced in plant cells transfected with plasmids encoding either ZmRb1 or human p130, a member of the Rb family. This suggests that ZmRb1 controls the G1/S transit in plant cells and is consistent with the fact that geminiviruses need an S-phase environment for DNA replication, as animal DNA tumor viruses do. Our results allow the extension of the Rb family of tumor suppressor proteins to plants and have implications on animal and plant strategies for cell growth control.

Antibodies to ribosomal P proteins and hepatic damage in undifferentiated CTD

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[Description of 31 pediatric cases of infection caused by human Parvovirus B 19]

FUNDAMENTALS

[corrected] Human Parvovirus B19 has been identified as the etiological agent implicated in several clinical forms of disease. The aim of this study was to define the clinical aspects observed in the children with human parvovirus infection in our hospital.

METHODS

A retrospective study was done in 31 pediatric cases observed in our hospital from January-92 to July-94; all had positive IgM against Parvovirus (determined by enzymoinmunoanalysis).

RESULTS

The most frequent signs and symptoms were fever in 66.6% of the cases and skin findings in 48%, manifested as typical infectious erythema in 26% and polimorphic nonspecific exanthema in the rest. There were variable blood manifestations, observed in 11 children (35%): Immune Thrombocytopenic purpura, Chronic anemia in immunocompromised hosts, bone marrow erithrophagocytosis and hemolytic crises in non-hemolytic anemia patients. The abnormal blood findings were mostly observed in children with compromised immunity. Articular disease was presented in four children (12%). Long lasting fever was observed in only one case.

CONCLUSIONS

In our sample the diversity of clinical forms of presentation of Parvovirus B19 infection is well documented as it is reported by several authors. Although other studies as polymerase chain reaction (PCR), nucleic acid hybridization, direct visualization of the virus or its particles, or viral antigen detection are desirable to confirm the serologic studies.

Helix-destabilizing activity of phi 29 single-stranded DNA binding protein: effect on the elongation rate during strand displacement DNA replication

The single-stranded DNA (ssDNA)-binding protein (SSB) of bacteriophage phi 29 is one of the virus-encoded proteins required for viral DNA replication. We have found that phi 29 SSB has helix-destabilizing activity since it removes secondary structure of the ssDNA in phi 29 replicative intermediates, as revealed by electron microscopy, and displaces oligonucleotides annealed to M13 ssDNA. To investigate the mechanism of the SSB-dependent stimulation of phi 29 DNA replication we have characterized the helix-destabilizing activity of phi 29 SSB and measured its effect on the DNA elongation rate by phi 29 DNA polymerase, which does not require an accessory helicase. The use of replication reactions where strand displacement is either required (phi 29 DNA replication) or not (conversion of primed M13 ssDNA into double-stranded DNA (dsDNA)) has allowed us to find that (1) strand displacement DNA replication was affected by lowering the temperature or by increasing the salt concentration, since the DNA elongation rate on the phi 29 template was three to fourfold slower than on primed M13 ssDNA, (2) under those conditions, addition of phi 29 SSB stimulated to different extents the DNA elongation rate during phi 29 DNA replication, whereas it had a marginal effect on primed M13 ssDNA replication, and (3) phi 29 SSB increased four to sixfold the phi 29 DNA elongation rate by phi 29 DNA polymerase strand displacement mutants, reaching approximately 50% the rate of the wild-type enzyme. The implications of the helix-destabilizing properties of the phi 29 SSB under conditions in which DNA opening is impaired are discussed.

[Winter epidemic of carbon monoxide poisoning in Badia]

OBJECTIVE

To find the incidence, morbidity and possible causes of the acute carbon monoxide poisonings (ACMP) which occurred in Badia between january 1992 and june 1993.

DESIGN

A longitudinal, retrospective study.

PATIENTS

Every Badia resident discharged from the Hospital Consortium of Parc Taulí, Sabadell with a diagnosis of ACMP and/or from Barcelona's Red Cross Hospital (RCH) after hyperbaric treatment was considered.

MEASUREMENTS AND RESULTS

Cases were identified using the hospital discharge records from Parc Taulí and the RCH. A systematic review of the primary care clinical records was undertaken. The causes of the poisoning were investigated by a technical committee and through the gas company carrying out inspections of dwellings in 1993. The incidence of ACMP was 76.5 per 100,000 inhabitants in 1992 and 109.4 per 100,000 in the first half of 1993. 94% of the 34 cases occurred in December, January, February and March. 50% of those affected were under 17. The number of cases per household varied between 2 and 5 people. The most common underlying cause was the existence of defects in the conduits taking fumes away from gas heaters. The gas review detected defects in installation in 54% of dwellings.

CONCLUSIONS

ACMP is a common and serious problem in our environment. The underlying causes and the high number of dwellings at risk have suggested a need for information campaigns in the community.

Identification and analysis of a retinoblastoma binding motif in the replication protein of a plant DNA virus: requirement for efficient viral DNA replication

Geminiviruses are plant DNA viruses with small genomes whose replication, except for the viral replication protein (Rep), depends on host proteins and, in this respect, are analogous to animal DNA tumor viruses, e.g. SV40. The mechanism by which these animal viruses create a cellular environment permissive for viral DNA replication involves the binding of a virally encoded oncoprotein, through its LXCXE motif, to the retinoblastoma protein (Rb). We have identified such a LXCXE motif in the Rep protein of wheat dwarf geminivirus (WDV) and we show its functional importance during viral DNA replication. Using a yeast two-hybrid system we have demonstrated that WDV Rep forms stable complexes with p130Rbr2, a member of the Rb family of proteins, and single amino acid changes within the LXCXE motif abolish the ability of WDV Rep to bind to p130Rbr2. The LXCXE motif is conserved in other members of the same geminivirus subgroup. The presence of an intact Rb binding motif is required for efficient WDV DNA replication in cultured wheat cells, strongly suggesting that one of the functions of WDV Rep may be the linking between viral and cellular DNA replication cycles. Our results point to the existence of a Rb-like protein(s) in plant cells playing regulatory roles during the cell cycle.

Upregulated expression of IL-4 receptors and increased levels of IL-4 in rheumatoid arthritis patients

The level of IL-4R expression on peripheral lymphocyte subsets from rheumatoid arthritis (RA) patients and controls was studied by flow cytometric analysis of the binding of phycoerythrin-labelled IL-4 (PE-IL-4). In normal lymphocytes, IL-4R is mainly expressed on CD19+ cells, although it was also seen, at lower levels, on CD3+, CD4+ and CD8+ cells. In RA patients, a significantly increased spontaneous expression of IL-4R was observed, compared with controls, in the CD3+, CD4+ and CD19+ cell subsets. No significant differences in IL-4R expression were found between patients receiving steroids and those who were not, suggesting that steroids are not involved in upregulating IL-4R levels in vivo. Because IL-4 is a potent upregulator of IL-4R, we considered the possibility that incremented levels of circulating IL-4 in RA accounted for the high surface expression of IL-4R. By ELISA, we found abnormally high levels of immunoreactive IL-4 in 35.13% of patient serum samples, while it was undetectable in control sera. In addition, we examined IL-4 mRNA expression by polymerase chain reaction (PCR) in the PBMC of patients and controls. IL-4 PCR products were observed in four out of 10 patients studied but in none of the controls. No correlation was observed between the seric concentrations of IL-4 and IL-4R, indicating that activator factors other than IL-4 contribute to the upregulation of IL-4R expression in RA. Since the patients' sedimentation rate and CRP values did not correlate with the concentration of circulating IL-4, we conclude that this lymphokine does not contribute to the deleterious effect of the disease. Rather, due to its antiinflammatory properties, the overproduction of IL-4 in RA may be a compensatory mechanism neutralizing the harmful effect of activated macrophages.

Soluble, but not immobilized, anti-IgM antibody inhibits post-activation events leading to T-cell-dependent B-cell differentiation

The potential for surface immunoglobulin-binding ligands to modify B-cell differentiation responses induced by activated T cells has been investigated. Activated T cells in human splenic mononuclear cells cultured on anti-CD3-coated plates induced B cells to produce large amounts of IgM and IgG. In this experimental system, cross-linking of B-cell antigen receptors by soluble, bivalent monoclonal or polyclonal anti-IgM antibodies completely inhibited IgM production, and greatly diminished IgG production, in a dose-dependent manner. Similar results were obtained using a F(ab')2 fragment of a goat anti-IgM antibody. Inhibition of B-cell differentiation by bivalent cross-linking reagents did not require the presence of antigen-presenting cells (APC), as comparable results were obtained in co-cultures of purified T and B cells. In contrast, enhanced immunoglobulin secretion was seen when surface IgM was cross-linked using anti-IgM antibody immobilized on the culture plate. Interestingly, activated T cells induced similar levels of expression on B cells of the activation antigens CD23, CD25 and CD71, and of class II molecules, irrespective of any treatment with soluble or immobilized anti-IgM antibody. This indicates that soluble anti-IgM specifically inhibits B-cell differentiation without altering initial events of T-cell-dependent B-cell activation.

Comparison of an oral rice-based electrolyte solution and a glucose-based electrolyte solution in hospitalized infants with diarrheal dehydration

This randomized trial compared the efficacy of a rice-based (50 g/L) oral rehydration solution with the standard glucose-based WHO/UNICEF solution in the treatment of 100 hospitalized infants, ages 3-18 months, with acute dehydrating diarrhea. The main outcomes examined were stool output and duration of diarrhea. Patients were placed on a "metabolic" bed so that intake and losses could be measured accurately throughout the study. Overall, 89% of patients were successfully rehydrated orally; the rehydration failure rate was similar in the two groups and it was significantly associated with infection by specific E. coli serotypes. Stool output in the first 24 h was 11% lower in the rice group (112 versus 126 ml/kg), but this difference was not significant. Neither stool output in the second 24 h nor total stool output were different between groups. The median duration of diarrhea was 3.8 days in the rice group and 3.9 days in the glucose group (p = NS). Other (secondary) outcomes, such as fluid intake, urine output, emesis losses, weight change, and electrolyte balance were also similar between the two groups. Some evidence of carbohydrate malabsorption was detected in 61% of the rice group versus 45% of the glucose group (p = NS) and was not associated with any particular treatment outcome. These results show that a rice-based oral rehydration solution is as efficacious as, but not better than the standard glucose-based solution in the treatment of infants with acute dehydrating diarrhea not associated with cholera.

Bent DNA in the large intergenic region of wheat dwarf geminivirus

Wheat dwarf virus (WDV) is a member of the geminivirus group, unique plant DNA viruses which replicate exclusively via dsDNA replication intermediates. The large intergenic region (LIR), a nontranscribed regulatory region, contains an inverted repeat with the potential to form a stem-loop structure in which the initiation site for WDV (+)strand (virion-sense) DNA replication has been mapped. In this work, we have studied by two-dimensional electrophoresis and by electron microscopy the DNA structure of the WDV LIR and we have identified a DNA sequence which confers a static DNA curvature. This is the first report of the occurrence of DNA bending in the regulatory region of a geminivirus genome. The bending locus, defined by an 80-bp cluster of A(T) tracts, is located downstream from the potential stem-loop. The A(T) tract proximal to the stem-loop structure is separated by 14 bp from the inverted repeat, and deletion of distal A(T) tracts abolished the curvature of the new WDV deltaLIR. The bending center maps approximately 80 bp downstream from the putative initiation site for (+)strand DNA replication and approximately 70 bp upstream from the TATA box for virion-sense transcription. The possible implications of the DNA bending locus as a regulatory element of WDV DNA replication and/or virion-sense transcription are discussed.

Medullary thyroid carcinoma mimicking an autonomous functioning nodule

A 42-year-old woman with a medullary thyroid carcinoma (MTC) inside of an autonomously functioning thyroid nodule is reported. The patient was initially diagnosed of a hyperfunctioning autonomous thyroid adenoma but the histopathological and immunohistochemistry study were diagnostic for a MTC. This is the first case of a medullary thyroid carcinoma associated with thyroid hyperfunction which was presented as a hot nodule in the scintigraphy. We propose a systematic performance of a fine needle biopsy in all thyroid nodules because of the possibility of carcinoma associated to functioning nodules could be present.

Centromeric dodeca-satellite DNA sequences form fold-back structures

The evolutionarily conserved centromeric dodeca-satellite DNA has an asymmetric distribution of guanine and cytosine residues resulting in one strand being relatively G-rich. This dodeca-satellite G-strand contains a GGGA-tract that is similar to the homopurine tracts found in most telomeric DNA sequences. Here, we show that the dodeca-satellite G-strand forms intramolecular hairpin structures that are stabilized by the formation of non-Watson-Crick G.A pairs as well as regular Watson-Crick G.C pairs. Special stacking interactions are also likely to contribute significantly to the stability of this structure. This hairpin conformation melts at relatively high temperature, around 75 degrees C, and is detected under many different ionic and pH conditions. As judged by electron microscopy visualization, these structures can be formed in a B-DNA environment. Under the same experimental conditions, neither the C-strand nor the double-stranded dodeca-satellite DNA were found to form any unusual DNA structure. A protein activity has been detected that preferentially binds to the single-stranded dodeca-satellite C-strand. The biological relevance of these results is discussed in view of the similarities to telomeric DNA.

Rapid detection of tuberculous and non-tuberculous mycobacteria by microscopic observation of growth on Middlebrook 7H11 agar

The rate of recovery and time to the detection of mycobacteria in clinical specimens were measured in traditional egg-based media cultures and on Middlebrook 7H11 agar plate cultures using microcolony detection. In the 5438 specimens processed, a total of 293 (5.4%) clinically relevant mycobacterial isolates were detected (Mycobacterium tuberculosis, n = 231; Mycobacterium avium complex, n = 60; Mycobacterium kansasii, n = 2). Of these, 227 (77%) and 237 (81%) isolates were detected on Lowenstein-Jensen medium and Coletsos medium, respectively, and 265 (90%) isolates were detected on Middlebrook 7H11 plates examined microscopically. The detection time was shorter with the microcolony detection method. While the Lowenstein-Jensen and Coletsos media required an average of 23 and 25 days, respectively, for first detection of mycobacteria, microcolony detection on Middlebrook 7H11 required an average of only 12 days. For acid-fast, stain-positive specimens that were culture positive for Mycobacterium tuberculosis, the average interval to positivity was nine days for the microcolony method compared with 20 and 21 days for the Lowenstein-Jensen and Coletsos media, respectively. Microscopic detection on Middlebrook 7H11 agar plates is a rapid, accurate and inexpensive method of detecting Mycobacterium tuberculosis and other clinically important mycobacteria.

[Treatment of puerperal endometritis. Evaluation of the efficacy and safety of clindamycin + gentamycin vs. penicillin + chloramphenicol + gentamycin]

This was a prospective, single-blind, comparative study in patients with diagnosis of puerperal endometritis, carried out at the Loayza Hospital in Lima, Peru. The objective of this study was to evaluate the efficacy and safety of clindamycin and gentamicin in the management of endometritis vs. penicillin, chloramphenicol and gentamicin for 10 days. Sixty-five patients were enrolled and 62 were evaluable for efficacy. Both treatment groups were comparable in the pre-treatment period in terms of age, history of pregnancies, controls by gynecologist, days of disease and fever, clinical symptoms like fever, pelvic pain, pulse, uterine size and in laboratory, in hematocrit and leukocytes count. In the culture of endometrium tissue, 27/32 patients (84.4%) in Group A (penicillin + CAF + gentamicin) and 27/30 patients (90%) in Group B (clindamycin + gentamicin) had positive cultures at baseline; 18 and 22 patients showed anaerobes; 8 and 4 patients showed anaerobes plus aerobes and, one patient in each treatment group showed aerobes only. Peptostreptococcus and Bacteroides fragilis were the most frequently isolated pathogens. Improvement in lochia fetidity was more rapid in Group B, it turned transparent and not fetid since day 3. Complete cure was significantly better in Group B 24/30 (80%) in comparison with Group A 16/32 (50%) (p = 0.02). Partial response was found in 15 patients (43.3%) in Group A and 5 patients (16.6%) in Group B. Only one case was considered as bacteriological failure in Group A and only one patient in Group B was considered as failure and required an additional operation due to residual abscess.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatocellular carcinoma and liver cell dysplasia in children with chronic liver disease

The histology of 72 livers from 72 children who underwent liver transplantation was reviewed. Nine children (12.5%) had hepatocellular carcinoma (HCC) and/or liver cell dysplasia (LCD) in their native livers. Ages at the time of transplantation ranged from 2 months to 11 years. Primary liver diseases included tyrosinemia (3), biliary atresia (2), chronic active hepatitis B (1), chronic active non-A non-B non-C hepatitis (1), idiopathic neonatal hepatitis (1), and neonatal iron storage disease (1). Explanted livers showed large multifocal HCC in two cases, incidental HCC in three, and dysplastic nodules in four. LCD also was present in three cases in conjunction with HCC. All patients had cirrhosis. Alpha-fetoprotein was measured in six children and was elevated in all six (range, 300 to 1,770,000 ng/mL; normal, 0 to 15 ng/mL). Abdominal computed tomography, ultrasonography, and/or magnetic resonance imaging showed large masses in two cases, but did not detect the tumors of less than 2 cm or the dysplastic nodules in the other seven children. After a follow-up period of 2 months to 3 years (mean, 19.8 +/- 12.1 months), eight children are alive and have no evidence of recurrence. The patient with neonatal iron storage disease died 2 months after transplantation, without evidence of tumor recurrence. The authors conclude that children with end-stage liver disease of diverse causes referred for liver transplantation may have LCD and/or HCC. Serial determination of alpha-fetoprotein and images studies may detect early lesions curable by liver transplantation.

Polyarthritis in kids associated with Mycoplasma putrefaciens

Fifteen two- to three-week-old kids, fed artificially with goats' milk from a dairy, were found to have polyarthritis. The most affected joints were the carpals, either unilaterally or bilaterally, and in some cases the tarsal joints. Mycoplasma putrefaciens was isolated from the joints which showed an acute fibrinopurulent arthritis. No clinical mastitis was detected in the dairy.

Decrease in detectable complement receptor type 1 levels on erythrocytes from patients with psoriatic polyarthritis

The complement receptor type 1 (CR1) levels on erythrocyte membranes from 23 patients with PsA was determined by using ELISA. Six patients had an axial form, the rest had peripheral arthritis (10 polyarthritis and seven oligoarthritis). A significant decrease in levels of this receptor was found in patients with polyarthritis compared with healthy controls. Non-significant differences were found when comparing the other two groups of patients with the controls, although the mean values of CR1 were lower in the patients' group. We also found an inverse correlation between CR1 levels and articular index, but not with ESR, CRP or disease duration. No differences in the CR1 density were obtained for HLA-B27 positive and HLA-B27 negative patients.

Complex formation between phage phi 29 single-stranded DNA binding protein and DNA

Bacteriophage phi 29 gene 5 encodes a single-stranded DNA (ssDNA) binding protein (SSB) which stimulates viral DNA replication. In the present study, a structural characterization of the complex between ssDNA and the phi 29 SSB was carried out using electron microscopy, band-shift assays and nuclease digestion as well as by monitoring changes in the intrinsic fluorescence of phi 29 SSB upon binding. Phage phi 29 SSB behaves as a monomer in solution and forms complexes with ssDNA which have a homogeneous structure, as if they consist of a continuous array of protein bound to DNA. Interaction of phi 29 SSB with ssDNA leads to a quenching of its tyrosine-dependent intrinsic fluorescence. This fluorescence quenching was directly proportional to the amount of phi 29 SSB bound to the ssDNA and the maximal quenching upon binding was very high (Qmax = 94.6 +/- 3.5%). Direct titration experiments have allowed us to estimate that the stoichiometry (n) of binding to ssDNA was 3.4(+/- 0.3) nucleotides per phi 29 SSB monomer. Both Qmax and n are independent of the salt concentration, suggesting the existence of only one major binding mode. At low salt concentrations, the effective binding constant (Keff = K omega) to poly(dT) was 2.2 x 10(5) M-1, the intrinsic binding constant (K) and the cooperativity parameter (omega) being 4.3 x 10(3) M-1 and 51, respectively. At increasing salt concentrations, the Keff exhibited a small, but significant, decrease. The possible functional significance of the binding parameters of phi 29 SSB during viral DNA replication is discussed.