Meningococcal disease in a kidney transplant recipient with mannose-binding lectin deficiency

We describe the case of a kidney transplant recipient who developed meningococcemia, without meningeal signs, 2 months after transplantation. Plasma levels of complement components C3, C4, and CH 50 were within the normal range. However, using a method to screen for the functional activity of all 3 pathways of complement, no activation via the mannose-binding lectin (MBL) pathway could be detected (0%). A subsequent quantification of MBL pathway components revealed normal levels of MASP 2 but undetectable amounts of MBL. To our knowledge, this is the first report of meningococcal disease after organ transplantation in a patient with MBL deficiency.     

Molecular cloning of the CD3 eta subunit identifies a CD3 zeta-related product in thymus-derived cells.

The CD3 eta subunit of the T-cell antigen receptor forms a heterodimeric structure with the CD3 zeta subunit in thymus-derived lymphoid cells and is apparently involved in signal transduction through the receptor. Here we report the primary structure of murine CD3 eta as deduced from protein microsequencing and cDNA cloning. The mature protein is divided into three domains: a 9-amino acid extracellular segment, a 21-amino acid transmembrane segment including a negatively charged residue characteristic of CD3 subunits, and a 155-amino acid cytoplasmic tail. The NH2-terminal sequences of CD3 eta and CD3 zeta are identical through amino acid 122 of each mature protein but then diverge in the remainder of their respective COOH-terminal regions, consistent with alternatively spliced products of a common gene. The cytoplasmic domain of CD3 eta is 42 amino acids larger than that of CD3 zeta but lacks one of six potential tyrosine phosphorylation sites as well as a putative nucleotide binding site previously identified in CD3 zeta. These structural features presumably account for the difference between CD3 eta and CD3 zeta function and are consistent with the notion that CD3 eta may be an important component of a T-cell receptor isoform(s) during thymic development.     

The increasing incidence of the hemolytic-uremic syndrome in King County, Washington: lack of evidence for ascertainment bias

The annual incidence of the hemolytic-uremic syndrome was determined for the well-defined population of King County, Washington, between 1971 and 1986, inclusive, to ascertain temporal trends in the epidemiology of this disease. The average annual incidence rose from 0.69 cases per 100,000 children under age 15 years between 1971 and 1975 to 1.77 cases between 1976 and 1980 and 1.74 cases between 1981 and 1986. The mean hematocrits, platelet counts, and blood urea nitrogen and creatinine concentrations on admission were similar in all periods, as were the mean length of hospital stay and the proportions of patients requiring erythrocyte and/or platelet transfusions and dialysis. These results indicate that the increased incidence of hemolytic-uremic syndrome in childhood has been sustained in King County, Washington, and that this increase is not due to ascertainment bias caused by the diagnosis of less severely ill cases. Further investigations are needed to determine whether this increased incidence is being experienced in other populations and to assess strategies for the prevention of microangiopathic sequelae to hemorrhagic colitis.     

Toxicogenetics of antiretroviral therapy: genetic factors that contribute to metabolic complications

Metabolic complications of antiretroviral therapy (ART) have emerged as a major concern for long-term, successful management of HIV infection. Variability in the response to ART between individuals has been increasingly linked to the genetic background of patients, as regards efficacy and susceptibility to adverse reactions (toxicogenetics). This review summarizes the biological and methodological background for the genetic prediction of metabolic toxicity of ART. Recent studies are discussed which suggest that single-nucleotide polymorphisms (SNPs) in several genes involved in lipid metabolism and lipid transport in the general population (ABCA1, APOA5, APOC3, APOE, CETP) might modulate plasma triglyceride and high-density lipoprotein cholesterol levels in HIV-infected patients. At present, genetic prediction of lipodystrophy is not possible. Lipodystrophy has been linked to an accumulation of mtDNA mutations, a finding causally associated with ageing phenotypes in animal models. No mutations in LMNA, a gene linked to rare, inherited forms of lipodystrophy, have been identified in small studies of patients with lipodystrophy, and a possible link to a TNF promoter SNP remains to be confirmed. With the rapidly decreasing cost of genetic testing, the main issues that need to be addressed prior to introduction of toxicogenetic prediction in HIV clinical practice include reproducibly high predictive values of SNP associations with clinically relevant and well defined metabolic outcomes, studies that evaluate the contribution of SNPs in the context of multi-SNP and haplotype analysis, and the validation of genetic markers in independent, large patient cohorts. Comprehensive, whole genome approaches are increasingly being used.     

Hospital Inpatient Admissions With Dehydration and/or Malnutrition in Medicare Beneficiaries Receiving Enteral Nutrition: A Cohort Study

Background: Enteral nutrition (EN) supports many older and disabled Americans. This study describes the frequency and cost of acute care hospitalization with dehydration and/or malnutrition of Medicare beneficiaries receiving EN, focusing on those receiving home EN. Methods: Medicare 5% Standard Analytic Files were used to determine Medicare spending for EN supplies and the proportion and cost of beneficiaries receiving EN, specifically home EN, admitted to the hospital with dehydration and/or malnutrition. Results: In 2013, Medicare paid $370,549,760 to provide EN supplies for 125,440 beneficiaries, 55% of whom were also eligible for Medicaid. Acute care hospitalization with dehydration and/or malnutrition occurred in 43,180 beneficiaries receiving EN. The most common principal diagnoses were septicemia (21%), aspiration pneumonitis (9%), and pneumonia (5%). In beneficiaries receiving EN at home, >one‐third (37%) were admitted with dehydration and/or malnutrition during a mean observation interval of 231 ± 187 days. Admitted patients were usually hospitalized more than once with dehydration and/or malnutrition (1.73 ± 1.30 admissions) costing $23,579 ± 24,966 per admitted patient, totaling >$129,685,622 during a mean observation interval of 276 ± 187 days. Mortality in the year following enterostomy tube placement was significantly higher for admitted compared with nonadmitted patients (40% vs 33%; P = .05). Conclusion: Acute care hospitalizations with dehydration and/or malnutrition in Medicare beneficiaries receiving EN were common and expensive. Additional strategies to reduce these, with particular focus on vulnerable populations such as Medicaid‐eligible patients, are needed.     

Substance P increases CCN2 dependent on TGF-beta yet Collagen Type I via TGF-beta1 dependent and independent pathways in tenocytes

Transforming growth factor beta 1 (TGFbeta-1) and connective tissue growth factor (CCN2) are important mediators of tissue repair and fibrosis, with CCN2 functioning as a downstream mediator of TGFβ-1. Substance P (SP) is also linked to collagen production in tenocytes. A link between SP, TGFbeta-1 and CCN2 has yet to be established in tenocytes or fibrogenic processes. We sought to determine whether SP induces tenocyte proliferation, CCN2, or collagen production via TGFbeta-1 signaling or independently in rat primary tenocytes. Tenocytes were isolated from rat tendons, cultured and stimulated by SP and/or TGFbeta-1. Cultured cells expressed proteins characteristic of tenocytes (vimentin and tenomodulin) and underwent increased proliferation dose dependently after SP and TGFbeta-1 treatments, alone or combined (more than SP alone when combined). SP induced TGFbeta-1 expression in tenocytes in both dose- and time-dependent manners. SP and TGFbeta-1, alone or combined, stimulated CCN2 expression in tenocytes and their supernatants after both 24 and 48 h of stimulation; a response blocked with addition of a TGFbeta-1 receptor inhibitor. In contrast, SP potentiated collagen type I secretion by tenocytes, a response abrogated by the TGFbeta-1 receptor inhibitor after 48 h of stimulation, but not after the shorter 24 h of stimulation. Our findings suggest that both SP and TGFbeta-1 can stimulate tenocyte fibrogenic processes, albeit differently. TGFbeta-1 pathway signaling was involved in CCN2 production at all time points examined, while SP induced collagen type I production independently prior to the onset of signaling through the TGFbeta-1 pathway.     

In vitro and in vivo evidence that the antiviral activity of 2'',3''-dideoxycytidine is target cell dependent in a feline retrovirus animal model.

2',3'-Dideoxycytidine (DDC) was evaluated for prophylactic antiviral activity in vitro and in vivo, using the feline leukemia virus (FeLV)-cat animal model. In vitro antiviral activity of DDC against FeLV was dependent upon the target cell used for infection. DDC (5 to 10 microM) inhibited FeLV infection of feline lymphoid cells by greater than 80%, while 6.07 to 12.13 microM DDC was required to similarly inhibit infection of feline fibroblasts. However, 43 to 384 microM DDC was needed to inhibit FeLV infection of primary bone marrow cells by greater than 80%. These in vitro results suggest that, although relatively low doses of DDC may be adequate to prevent infection of feline lymphoid cells, 8- to 80-times-higher doses may be necessary to block infection of bone marrow cells, a primary target cell type for FeLV infection. In vivo studies with DDC consisted of pharmacokinetic and toxicity determinations and evaluation of the prophylactic antiviral activity against FeLV in cats. Clearance and half-life values for DDC in cats were 6.5 ml/min per kg and 54.7 min, respectively. In the prophylactic studies, DDC was administered by continuous intravenous infusion at doses of 22, 15, 10, and 5 mg/kg per h for 28 days in most animals. Cats were challenged intravenously with FeLV 1 to 3 days after drug treatment began. Doses of 22 and 15 mg/kg per h were extremely toxic, causing death in 8 of 10 cats. The mg/kg per h dose was slightly toxic, causing chronic progressive thrombocytopenia over the 28-day treatment period. Of 10 cats given 10 to 5 mg of DDC per kg per h, only one was completely protected from FeLV antigenemia. However, conversion to positive FeLV antigenemia status was delayed by 2 to 7 weeks in seven of nine remaining animals. Interestingly, FeLV infection of bone marrow cells, as indicated by FELV antigen in peripheral blood neutrophils, was only slightly delayed by 0 to 2 weeks, except in the case of the one protected cat, and usually preceded conversion to antigenemia. This pattern of neutrophils becoming antigen positive before detection of antigenemia was not seen in FeLV challenge control animals and indicates that the antiviral activity of DDC may be incomplete during DDC treatment. Results of our in vitro and in vivo studies suggest that feline bone marrow cells may remain partially susceptible to FeLV infection at tolerated doses, while other somatic target tissues (i.e., lymphoid or epithelial tissues) may be protected from infection. Incomplete inhibition of FeLV infection permitted focal bone marrow infection to develop in cats given DDC. These loci of infection served as virus reservoirs which, subsequent to discontinuation of DDC treatment, permitted spread of infection to tissues previously protected during treatment.     

Function of wild-type or mutant Rac2 and Rap1a GTPases in differentiated HL60 cell NADPH oxidase activation

Studies of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation in a cell-free system showed that the low molecular-weight guanosine triphosphatase (GTPase) Rac was required, and that Rap1a may participate in activation of the catalytic complex. Full-length posttranslationally modified Rac2 was active, whereas only the 1-166 truncated form of Rap1a was functional in the cell-free system, and thus, clarification of the function of Rap1a and Rac2 in intact human phagocytes is needed to provide further insight into their roles as signal transducers from plasma membrane receptors. In the present studies, oligonucleotide-directed mutagenesis was used to introduce a series of mutations into human rap1a or rac2 in the mammalian expression vector pSR alpha neo. HL60 cells transfected with wild-type or mutated rac2 or rap1a cDNA constructs and control HL60 cells transfected with the pSR alpha neo vector containing no inserted cDNA were selected in G418-containing media, then subclones were isolated. Compared with the parent HL60 cells, each of the stable transfected cell lines differentiated similarly into neutrophil-like cells and expressed comparable levels of NADPH oxidase components p47- phox, p67-phox and gp91-phox. The differentiated vector control cell line produced O2. in response to receptor stimulation at rates that were not significantly different from parent HL60 cells. O2-. production by differentiated cell lines expressing mutated N17 Rap1a or N17 Rac2 dominant-negative proteins was inhibited, whereas O2-. production by the subline overexpressing wild-type Rap1a was increased by fourfold. O2-. production by the differentiated cell line expressing GTPase-defective V12 Rap1a was also significantly inhibited, a finding that is consistent with a requirement for cycling between guanosine diphosphate- and GTP-bound forms of Rap1a for continuous NADPH oxidase activation in intact neutrophils. A model is proposed in which Rac2 mediates assembly of the p47 and p67 oxidase components on the cytosolic face of the plasma membrane via cytoskeletal reorganization, whereas Rap1a functions downstream as the final activation switch involving direct physical interaction with the transmembrane flavocytochrome component of the NADPH oxidase.