Dengue: emergence as a global public health problem and prospects for control

Dengue causes more illness and death than any other arboviral infection: there are at least 20 million infections in the world each year and several hundred thousand cases of a severe, life-threatening syndrome known as dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS). In recent years, the geographical range of dengue has extended and DHF/DSS is occurring in new areas and with increased incidence. The reasons for the resurgence are complex, but parallel demographic changes and reduced efforts towards disease control. Control of dengue currently depends on controlling its mosquito vector. However, development of a vaccine offers greater hope in the long-term. The dengue group of flaviviruses is unique in that it comprises 4 distinct serotypes which have the potential to cause sequential infections with increased severity. It is reasoned, therefore, that any vaccine should induce solid immunity to all 4 serotypes. Knowledge regarding dengue immunity and pathogenesis is rapidly advancing and it is reasonable to believe that this information can be used to devise a safe and efficacious vaccine for dengue, but it seems unlikely that this will become available in the near future.

Proline metabolism in the wild-type and in a salt-tolerant mutant of nicotiana plumbaginifolia studied by (13)C-nuclear magnetic resonance imaging

To obtain insight into the link between proline (Pro) accumulation and the increase in osmotolerance in higher plants, we investigated the biochemical basis for the NaCl tolerance of a Nicotiana plumbaginifolia mutant (RNa) that accumulates Pro. Pro biosynthesis and catabolism were investigated in both wild-type and mutant lines. (13)C-Nuclear magnetic resonance with [5-(13)C]glutamate (Glu) as the Pro precursor was used to provide insight into the mechanism of Pro accumulation via the Glu pathway. After 24 h under 200 mM NaCl stress in the presence of [5-(13)C]Glu, a significant enrichment in [5-(13)C]Pro was observed compared with non-stress conditions in both the wild type (P2) and the mutant (RNa). Moreover, under the same conditions, [5-(13)C]Pro was clearly synthesized in higher amounts in RNa than in P2. On the other hand, measurements of enzyme activities indicate that neither the biosynthesis via the ornithine pathway, nor the catabolism via the Pro oxidation pathway were affected in the RNa mutant. Finally, the regulatory effect exerted by Pro on its biosynthesis was evaluated. In P2 plantlets, exogenous Pro markedly reduced the conversion of [5-(13)C]Glu into [5-(13)C]Pro, whereas Pro feedback inhibition was not detected in the RNa plantlets. It is proposed that the origin of tolerance in the RNa mutant is due to a mutation leading to a substantial reduction of the feedback inhibition normally exerted in a wild-type (P2) plant by Pro at the level of the Delta-pyrroline-5-carboxylate synthetase enzyme.

Infectious complications in geriatric renal transplant patients: comparison of two immunosuppressive protocols

BACKGROUND

It has been well documented that a regimen of mycophenolate mofetil (MMF), cyclosporine (CsA), and prednisone (Pred) reduces the incidence of acute rejection in renal transplant recipients, as compared with previous regimens based on azathioprine (AZA), CsA, and Pred. In the general renal transplant patient population, immunosuppressive regimens that include MMF are usually well tolerated. It is not clear whether this holds true for older transplant recipients, who may be more susceptible to complications from the greater immunosuppression conferred by MMF.

METHODS

We retrospectively analyzed our geriatric renal transplant population (age >60 years, 1990-1998) and compared a cohort of 46 patients treated with AZA, Pred, and CsA to a cohort of 45 patients treated with MMF, Pred, and CsA.

RESULTS

There were no significant differences between the groups with regard to pretransplantation demographics. Patient and graft survival during the first year was not significantly different between the groups. During the first year of follow-up, we observed 27 infections requiring hospitalization in 15 patients in the MMF-treated group as compared with 10 infections in 7 patients in the AZA-treated group. A Cox proportional hazard model accounting for the above mentioned covariates isolated MMF versus AZA as a significant risk factor for the occurrence of serious infectious events (all: P<0.01; cytomegalovirus, fungal: P<0.01).

CONCLUSION

We conclude that an immunosuppressive regimen of MMF, CsA, and Pred seems to be correlated with an increased incidence of infectious adverse events as compared with AZA, CsA, and Pred in elderly patients.

The effect of body mass index on long-term renal allograft survival

BACKGROUND

A number of factors have been implicated in decreasing long-term renal graft survival. Factors such as living versus cadaveric donor status, acute rejection, and HLA matching have been studied in detail. Mild obesity defined as a body mass index (BMI) of >25 has been found to have a deleterious effect on a number of physiologic processes. We studied the effect of a BMI >25 on long-term renal transplantation outcome.

METHODS

A total of 405 patients who underwent transplantation at Saint Barnabas Medical Center from 1990 to 1997 were evaluated. All known variables impacting on long-term graft function were collected. Multivariate analysis utilizing the Cox-proportional hazard model and Kaplan-Meier actuarial survival were applied to these risk factors.

RESULTS

BMI >25 was isolated as an independent risk factor for both decreased graft survival and patient survival (relative risk 2.0 for each). Cadaveric donor status, acute rejection, and use of azathioprine versus mycophenolate mofetil were the only other significant risk factors.

CONCLUSIONS

Mild obesity before transplantation has a negative impact on long-term renal graft and patient survival.

Tumor necrosis factor-alpha at acute myocardial infarction in rats and effects on cardiac fibroblasts

Tumor necrosis factor-alpha (TNF-alpha) biosynthesis by the myocardium in response to several diseases has not been solely associated with activation of the immune system but may also serve as a stress response in the context of neurohumoral gene activation. In this regard, beneficial as well as adverse effects of the cytokine on injured myocardium have been reported. TNF-alpha has been suggested to modulate myocyte and fibroblast cell growth and function. Now, in a rat model of acute myocardial infarction TNF-alpha expression and effects on cardiac fibroblast were determined. TNF-alpha was detected in rat hearts with acute myocardial infarction, parallel to the presence of proliferating fibroblasts, at the border zone of the infarct region, to a lesser degree in the infarct zone and was still present in the surviving myocardium. Similarly, the TNF-alpha mRNA level was, compared to sham-operated heart, higher in the infarct area. In the remote myocardium, a trend to an elevated TNF-alpha mRNA level was observed. TNF-alpha stimulated proliferation and expression of fibronectin in fibroblasts isolated from the infarct, non-infarct-region and sham-operated hearts. Angiotensin II is mitogenic for fibroblasts post-myocardial infarction and effects might be mediated indirectly by TNF-alpha. Addition of a neutralising anti-TNF-alpha antibody inhibited angiotensin II stimulated proliferation of fibroblasts only from the infarcted myocardium. The regional differences in TNF-alpha protein and mRNA levels, parallel to proliferating fibroblasts and proliferative effects may foster the reparative, reactive and adverse post-infarct remodeling of the heart.

Correlation of pseudohypoxemia and leukocytosis in chronic lymphocytic leukemia

Pseudohypoxemia has been reported in leukemic patients with extreme leukocytosis, and it is characterized by a low oxygen saturation on arterial blood gas analysis despite normal saturation on pulse oximetry. We report the case of a 51-year-old man with chronic lymphocytic leukemia and an elevated white blood cell (WBC) count after splenectomy, his progressive postoperative pseudohypoxemia gradually improved as the leukocytosis was lowered by chemotherapy. We believe this is the first report to show a statistically significant correlation between the WBC count and the degree of pseudohypoxemia in a patient with leukemia.

Lithium augmentation fails to reduce symptoms in poorly responsive schizophrenic outpatients

BACKGROUND

Nearly one third of patients suffering from schizophrenia do not fully respond to antipsychotic medication. Safe, effective, and cost-efficient methods to reduce symptoms are clearly needed; therefore, lithium as an adjunct to fluphenazine decanoate was tested in a placebo-controlled trial in outpatients who were part of the Treatment Strategies of Schizophrenia (TSS) study.

METHOD

Forty-one patients with DSM-III schizophrenia or schizoaffective disorder were assigned to either adjunctive lithium or placebo after at least 6 months of fluphenazine decanoate treatment to stabilize symptoms had failed. The trial was designed for 8 weeks of treatment, and patients assigned to placebo could afterward be administered lithium in an 8-week, open-label study.

RESULTS

Assessment of the intent-to-treat analysis revealed no significant differences in demographic variables between the lithium and placebo groups. Although both groups showed significant (p = .00135) improvement as measured by total scores on the Brief Psychiatric Rating Scale (BPRS), there were no significant differences in response between the lithium and placebo groups. Patients originally treated with placebo added to neuroleptic did not have significantly greater improvement when receiving open-label adjunctive lithium.

CONCLUSION

Although success with lithium augmentation therapy for persistent psychosis has been reported in the past, this study of well-characterized patients showed no benefit for this common strategy, thus indicating that care be used in utilizing lithium augmentation.

Caval contribution to flow in the branch pulmonary arteries of Fontan patients with a novel application of magnetic resonance presaturation pulse

BACKGROUND

A complete understanding of fluid mechanics in Fontan physiology includes knowledge of the caval contributions to right (RPA) and left (LPA) pulmonary arterial blood flow, total systemic venous return, and relative blood flow to each lung.

METHODS AND RESULTS

Ten Fontan patients underwent cine MRI. Three cine scans of the pulmonary arteries were performed: (1) no presaturation pulse, (2) a presaturation pulse labeling inferior vena cava (IVC) blood (signal void), and (3) a presaturation pulse labeling superior vena cava (SVC) blood. The relative signal decrease is proportional to the amount of blood originating from the labeled vena cava. This method was validated in a phantom. Whereas 60+/-6% of SVC blood flowed into the RPA, 67+/-12% of IVC blood flowed toward the LPA. Of the blood in the LPA and RPA, 48+/-14% and 31+/-17%, respectively, came from the IVC. IVC blood contributed 40+/-16% to total systemic venous return. The distributions of blood to each lung were nearly equal (RPA/LPA blood=0.94+/-11).

CONCLUSIONS

In Fontan patients with total cavopulmonary connection, SVC blood is directed toward the RPA and IVC blood is directed toward the LPA. Although the right lung volume is larger than the left, an equal amount of blood flow went to both lungs. LPA blood is composed of equal amounts of IVC and SVC blood because IVC contribution to total systemic venous return is smaller than that of the SVC. This technique and these findings can help to evaluate design changes of the systemic venous pathway to improve Fontan hemodynamics.

The Arabidopsis thaliana dhdps gene encoding dihydrodipicolinate synthase, key enzyme of lysine biosynthesis, is expressed in a cell-specific manner

Lysine synthesis in prokaryotes, some phycomycetes and higher plants starts with the condensation of L-aspartate-beta-semialdehyde (L-ASA) and pyruvate into dihydrodipicolinic acid. The enzyme that catalyses this step, dihydrodipicolinate synthase (DHDPS), is inhibited by the end-product lysine and is therefore thought to have a regulatory control on lysine synthesis. We have cloned and sequenced an Arabidopsis thaliana DNA fragment containing 900 bases upstream of the dhdps coding sequence. A transcriptional fusion of this fragment with the beta-glucuronidase reporter gene (uidA. Gus) was used to study the transcription properties of this promoter fragment (DS). No lysine-induced repression on transcription could be detected. Expression of DS-Gus activity in transformed Arabidopsis thaliana and Nicotiana tabacum was found to be cell type-specific. In the vegetative parts of the plant, GUS activity was located in meristems and young vasculature of roots, in vasculature of stem and leaves and in the meristems of young shoots. In flowers, high expression was found in the carpels, style, stigma, developing embryos, tapetum of young anthers and pollen. We demonstrated that the Arabidopsis DS promoter can direct its cell type-specific expression in a heterologous plant, Nicotiana tuabacum. The importance of transcriptional regulation of the dhdps gene, and in more general genes involved in amino acid biosynthesis, is discussed.

Ecs, an ABC transporter of Bacillus subtilis: dual signal transduction functions affecting expression of secreted proteins as well as their secretion

ecs is a three-cistron operon of Bacillus subtilis, encoding proteins with similarity to the ATPase (EcsA) and hydrophobic components (EcsB) of ABC transporters. The ecsA26 point mutation was shown to cause a strong processing defect of a secreted alpha-amylase precursor (preAmyQ) and of three other exoproteins. Northern analysis of the level of amyQ mRNA showed that ecsA26 also decreases amyQ transcription. This effect too was pleiotropic, as judged by a drastic decrease in the expression from an exoprotease promoter of a reporter protein. A knockout mutation of the ecsB cistron caused a processing defect similar to ecsA26 but, unlike ecsA26, did not affect amyQ transcription. These was also no defect in transcription in the ecsA ecsB double mutant. Thus, an intact ecsB product was required for the downregulation of amyQ by the mutant ecsA. These results suggest a dual regulatory function for Ecs, in which Ecs, possibly as part of a signal transduction mechanism, regulates some component(s) of the protein secretion apparatus as well as secretory protein transcription in a co-ordinated fashion.

A novel human type II cytokeratin, K6hf, specifically expressed in the companion layer of the hair follicle

In an attempt to identify new members of the human type II hair keratin family by means of 3'- and 5'-RACE methods and cDNA from anagen hair follicles, we detected a sequence that encoded a hitherto unknown type II cytokeratin. The novel cytokeratin comprises 251 amino acids and exhibits the highest sequence homology with K5. Comparative one- and two-dimensional western blots of keratins from anagen hair bulbs, containing or not containing the outer and inner root sheaths (ORS/IRS), and from footsole epidermis with an antibody against the new cytokeratin, revealed its comigration with K6 and its expression in the ORS/IRS complex. We have therefore named the new cytokeratin K6hf, to distinguish it from the various K6 isoforms and to indicate its expression in the hair follicle. Both in situ hybridization with a K6hf-specific cRNA probe and indirect immunofluorescence with the K6hf antibody showed that K6hf is exclusively expressed in the so-called "companion layer" of the hair follicle, a single layered band of flat and vertically oriented cells between the cuboidal ORS cells and the IRS that stretches from the lowermost bulb region to the isthmus of the follicle. Concomitant K17 and K16 expression studies showed that besides suprabasal ORS cells, these cytokeratins are sequentially expressed subsequent to K6hf in companion cells above the hair bulb. Our study confirms the view of a vertically oriented companion layer differentiation. The clearly delayed K17 and K16 expression relative to that of K6hf in companion cells most probably excludes these keratins as possible type I partners of K6hf and suggests the existence of a still unknown type I partner of its own. Thus, not only morphologically but also biochemically, the companion layer is different from the ORS and can therefore be regarded as an independent histologic compartment of the hair follicle.

Molecular cloning and expression of a cDNA sequence encoding histidinol phosphate aminotransferase from Nicotiana tabacum

A Nicotiana tabacum cDNA sequence encoding histidinol phosphate aminotransferase (HPA) was isolated by functional complementation of an Escherichia coli histidine auxotroph (UTH780). The enzymatic assay has confirmed that the isolated cDNA encodes a functional HPA protein. Amino acid sequence alignment of the HPA protein from N. tabacum, Saccharomyces cerevisiae and E. coli revealed that, despite the low degree of identity, some residues were found to be highly conserved. The predicted protein contains a transit peptide sequence at the amino-terminal end, suggesting a chloroplastic localization of the HPA enzyme. Western blot analysis demonstrated that the deduced HPA protein and the mature HPA protein have an apparent molecular mass of about 45 kDa and 40 kDa respectively. Gene copy number estimation by Southern analysis indicates the presence of at least two genes per haploid genome coding for this protein in Nicotiana sp. From northern analysis results, the gene seems to be highly expressed in green tissues and the detected transcript showed a single band of expected molecular size.

Potential interaction of troglitazone and cyclosporine

BACKGROUND

Troglitazone (Rezulin) is a promising new oral hypoglycemic agent recently approved by the Federal Drug Administration for use in type II diabetes mellitus. Although troglitazone is not metabolized by the cytochrome p450 3A isozyme family, it is a potential inducer of this system. Other medications, e.g., rifampin and phenobarbital, which also induce p450 3A activity, have been reported to significantly decrease cyclosporine (CsA) concentrations.

METHODS

We report a case of a stable renal transplant patient who had a decrease in CsA concentration after beginning troglitazone and who subsequently developed an acute rejection episode. We then reviewed all stable renal patients begun on troglitazone over the previous 6 months.

RESULTS

The seven transplant patients who had been started on troglitazone therapy experienced a statistically and clinically significant decrease in CsA 12-hr trough levels immediately after the institution of troglitazone therapy.

CONCLUSION

A potential interaction exists between troglitazone and CsA. Transplant patients on CsA who receive troglitazone therapy should be monitored closely.

Isolation of the ornithine-delta-aminotransferase cDNA and effect of salt stress on its expression in Arabidopsis thaliana

To evaluate the relative importance of ornithine (Orn) as a precursor in proline (Pro) synthesis, we isolated and sequenced a cDNA encoding the Orn-delta-aminotransferase (delta-OAT) from Arabidopsis thaliana. The deduced amino acid sequence showed high homology with bacterial, yeast, mammalian, and plant sequences, and the N-terminal residues exhibited several common features with a mitochondrial transit peptide. Our results show that under both salt stress and normal conditions, delta-OAT activity and mRNA in young plantlets are slightly higher than in older plants. This appears to be related to the necessity to dispose of an easy recycling product, glutamate. Analysis of the expression of the gene revealed a close association with salt stress and Pro production. In young plantlets, free Pro content, Delta1-pyrroline-5-carboxylate synthase mRNA, delta-OAT activity, and delta-OAT mRNA were all increased by salt-stress treatment. These results suggest that for A. thaliana, the Orn pathway, together with the glutamate pathway, plays an important role in Pro accumulation during osmotic stress. Conversely, in 4-week-old A. thaliana plants, although free Pro level also increased under salt-stress conditions, the delta-OAT activity appeared to be unchanged and delta-OAT mRNA was not detectable. Delta1-pyrroline-5-carboxylate synthase mRNA was still induced at a similar level. Therefore, for the adult plants the free Pro increase seemed to be due to the activity of the enzymes of the glutamate pathway.

Continence nurses: a survey of who they are and what they do

This survey is the first report on the characteristics, functions, and barriers to practice reported by continence care nurses in the United States. The data obtained provide valuable information regarding a new subspecialization in nursing.

3-Nitrotyrosine in the proteins of human plasma determined by an ELISA method

The modification of tyrosine residues in proteins to 3-nitrotyrosine by peroxynitrite or other potential nitrating agents has been detected in biological systems that are subject to oxidative stress. A convenient semi-quantitative method has been developed to assay nitrated proteins in biological fluids and homogenates using a competitive ELISA developed in our laboratory. This assay selectivity detected 3-nitro-l-tyrosine residues in a variety of peroxynitrite-treated proteins (BSA, human serum albumin (HSA), alpha1-antiprotease inhibitor, pepsinogen and fibrinogen) and also in a nitrated peptide, but had a low affinity for free 3-nitro-L-tyrosine and 3-chloro-L-tyrosine. The IC50 values for the inhibition of antibody binding by different nitrated proteins were in the range 5-100 nM, suggesting that the antibody discriminated between nitrotyrosine residues in different environments. The presence of nitrotyrosine in plasma proteins was detected by Western blot analysis and quantified by the ELISA. A concentration of 0. 12+/-0.01 microM nitro-BSA equivalents was measured in the proteins of normal plasma which was increased in peroxynitrite-treated plasma and was elevated in inflammatory conditions. HSA and low-density lipoprotein (LDL) isolated from plasma contained 0.085+/-0.04 and 0. 03+/-0.006 nmol nitro-BSA equivalents/mg protein, respectively. Comparison of the level of nitration in peroxynitrite-treated HSA and LDL in the presence and absence of plasma indicates that nitration and presumably oxidation is inhibited by plasma antioxidants. The presence of nitrotyrosine in LDL is consistent with previous reports implicating peroxynitrite in the oxidative modification of lipoproteins and the presence of a low concentration of oxidized LDL in the blood.