Separation of younger red cells with improved survival in vivo: An approach to chronic transfusion therapy

Transfusion of donor blood containing predominantly younger red cells with prolonged survival in vivo could significantly reduce the iron overload of patients requiring chronic transfusion. Age-dependent separation of red cells can be obtained by buoyant density centrifugation on isotonic solutions of arabino-galactane. By this technique, rabbit red cells were separated on a single layer of arabino-galactane and the appropriate fraction, after being labeled with (51)Cr, was reinfused into the donor. The survival in vivo was calculated by a mathematical model which corrects for both (51)Cr elution and random loss. There was a significant difference in survival in vivo between the light young red cells and the heavy old red cells. The potential survival in vivo of the 50% lightest red cells was 56 days, compared to 28 days for the heaviest red cells. Arabino-galactane appeared to be devoid of acute toxicity and of strong antigenicity and it did not appear to adhere to the red cell stroma. These data extrapolated to humans indicate that it may be feasible and advantageous to use red cells fractionated by this technique for transfusion. The 50% lightest human red cells can be expected to have a mean survival of 88 days, compared with 60 days for unfractionated blood. Transfusion of young red cells could significantly reduce the iron overload for patients requiring chronic transfusion, by avoiding infusion of the oldest red cells, which contribute equally to iron overload yet offer only transient survival in vivo.     

High-Throughput RNAi Screening Identifies a Role for the Osteopontin Pathway in Proliferation and Migration of Human Aortic Smooth Muscle Cells

Purpose

Understanding of the mechanisms of vascular smooth muscle cells (VSMCs) phenotypic regulation is critically important to identify novel candidates for future therapeutic intervention. While HTS approaches have recently been used to identify novel regulators in many cell lines, such as cancer cells and hematopoietic stem cells, no studies have so far systematically investigated the effect of gene inactivation on VSMCs with respect to cell survival and growth response.

Methods and Results

257 out of 2000 genes tested resulted in an inhibition of cell proliferation in HaoSMCs. After pathway analysis, 38 significant genes were selected for further study. 23 genes were confirmed to inhibit proliferation, and 13 genes found to induce apoptosis in the synthetic phenotype. 11 genes led to an aberrant nuclear phenotype indicating a central role in cell mitosis. 4 genes affected the cell migration in synthetic HaoSMCs. Using computational biological network analysis, 11 genes were identified to have an indirect or direct interaction with the Osteopontin pathway. For 10 of those genes, levels of proteins downstream of the Osteopontin pathway were found to be down-regulated, using RNAi methodology.

Conclusions

A phenotypic high-throughput siRNA screen could be applied to identify genes relevant for the cell biology of HaoSMCs. Novel genes were identified which play a role in proliferation, apoptosis, mitosis and migration of HaoSMCs. These may represent potential drug candidates in the future.

     

Clinical phenotype,biochemical profile,and treatment in 19 patients with arginase 1 deficiency

Background

Arginase 1 (ARG1) deficiency is a rare urea cycle disorder (UCD). This hypothesis-generating study explored clinical phenotypes, metabolic profiles, molecular genetics, and treatment approaches in a cohort of children and adults with ARG1 deficiency to add to our understanding of the underlying pathophysiology.

Methods

Clinical data were retrieved retrospectively from physicians using a questionnaire survey. Plasma aminoacids, guanidinoacetate (GAA), parameters indicating oxidative stress and nitric oxide (NO) synthesis as well as asymmetric dimethylarginine (ADMA) were measured at a single study site.

Results

Nineteen individuals with ARG1 deficiency and 19 matched controls were included in the study. In patients, paraparesis, cognitive impairment, and seizures were significantly associated suggesting a shared underlying pathophysiology. In patients plasma GAA exceeded normal ranges and plasma ADMA was significantly elevated. Compared to controls, nitrate was significantly higher, and the nitrite:nitrate ratio significantly lower in subjects with ARG1 deficiency suggesting an advantage for NO synthesis by inducible NO synthase (iNOS) over endothelial NOS (eNOS). Logistic regression revealed no significant impact of any of the biochemical parameters (including arginine, nitrates, ADMA, GAA, oxidative stress) or protein restriction on long-term outcome.

Conclusion

Three main hypotheses which must be evaluated in a hypothesis driven confirmatory study are delineated from this study: 1) clinical manifestations in ARG1 deficiency are not correlated with arginine, protein intake, ADMA, nitrates or oxidative stress. 2) GAA is elevated and may be a marker or an active part of the pathophysiology of ARG1 deficiency. 3) Perturbations of NO metabolism merit future attention in ARG1 deficiency.

     

Challenges in the diagnosis and management of acromegaly: a focus on comorbidities

Introduction

Acromegaly is a rare, insidious disease resulting from the overproduction of growth hormone (GH) and insulin-like growth factor 1 (IGF-1), and is associated with a range of comorbidities. The extent of associated complications and mortality risk is related to length of exposure to the excess GH and IGF-1, thus early diagnosis and treatment is imperative. Unfortunately, acromegaly is often diagnosed late, when patients already have a wide range of comorbidities. The presence of comorbid conditions contributes significantly to patient morbidity/mortality and impaired quality of life.

Methods

We conducted a retrospective literature review for information relating to the diagnosis of acromegaly, and its associated comorbidities using PubMed. The main aim of this review is to highlight the issues of comorbidities in acromegaly, and to reinforce the importance of early diagnosis and treatment.

Findings and conclusions

Successful management of acromegaly goes beyond treating the disease itself, since many patients are diagnosed late in disease evolution, they present with a range of comorbid conditions, such as cardiovascular disease, diabetes, hypertension, and sleep apnea. It is important that patients are screened carefully at diagnosis (and thereafter), for common associated complications, and that biochemical control does not become the only treatment goal. Mortality and morbidities in acromegaly can be reduced successfully if patients are treated using a multimodal approach with comprehensive comorbidity management.

     

Arrhythmia device lead extraction: factors that necessitate laser assistance

BACKGROUND:

The removal of pacemaker and implantable cardioverter defibrillator (ICD) leads has become a common procedure. The need for laser use has considerable implications regarding cost and expertise. It is not an option at all centres and introduces an element of risk to the procedure. Anticipation of the need for laser assistance may be of benefit to procedure planning.

METHODS:

Data on all patients undergoing lead extraction at London Health Sciences Centre (London, Ontario) between July 2001 and October 2006 were reviewed. Variables were assessed for independent association with the need for laser assistance. A prediction rule for laser use was created based on the multivariate model.

RESULTS:

From July 2001 to October 2006, 154 patients underwent lead extraction, with laser assistance required in 106 patients (68.8%). One hundred seven patients (69.5%) had pacemakers and the remainder had ICDs. The mean (± SD) device age was 7.6±5.7 years, with 1.9±0.9 leads requiring extraction. Clinical success was achieved in 152 patients (98.7%). Multivariate analysis revealed that laser use was less likely among men (OR 0.24, 95% CI 0.069 to 0.84; P=0.026) and among septic patients (OR 0.25, 95% CI 0.072 to 0.84; P=0.025), and more likely with ICDs than pacemakers (OR 4.40, 95% CI 1.50 to 12.91; P=0.0069) and with each additional year of device age (OR 1.46 per year, 95% CI 1.26 to 1.70; P<0.0001).

CONCLUSIONS:

Laser assistance was required in 68.8% of cases, with clinical success in 98.7% of patients. Laser use was less likely among septic patients and men, and more likely with ICD leads and increasing time since lead implant. It was not possible to derive an accurate prediction rule for cases that would not need laser assistance. Therefore, it is prudent to ensure that a laser and appropriate infrastructure is available for lead extractions, and that the patient is aware of the possible need for laser assistance, along with the risks entailed.     

Comparison of low-dose pegylated interferon versus standard high-dose pegylated interferon in combination with ribavirin in patients with chronic hepatitis C with genotype 3: an Indian experience

Background and Aims: In chronic hepatitis C virus (HCV) infection with genotype 3, therapy with pegylated interferon (peg‐IFN) alfa‐2b in a dose of 1.5 μg/kg/week and ribavirin (800–1000 mg/day) is recommended for 24 weeks. Reduced doses of peg‐IFN may increase compliance and decrease cost and adverse events. This study aimed to assess the safety and efficacy of two different regimens of peg‐IFN alfa‐2b, in combination with ribavirin, in genotype 3 patients. Methods: A total of 103 liver biopsy–proven chronic HCV patients with genotype 3, having alanine aminotransferase levels >1.2 × ULN and positive HCV‐RNA were randomized into two groups: group I (n = 76; age, 43.1 ± 11.4 years; male/female, 67/9) received peg‐IFN 1.0 μg/kg/week + ribavirin 10.6 mg/kg/day, while group II (n = 27; age, 37.3 ± 11.6 years; male/female, 21/6) received peg‐IFN 1.5 μg/kg/week + ribavirin 10.6 mg/kg/day. Patients in both groups were treated for 24 weeks. End of treatment viral response (ETVR) and sustained viral response (SVR) after a 6‐month follow‐up period were assessed. Results: In both groups I and II, one patient was lost to follow‐up, while one patient in group II withdrew due to side‐effects. ETVR was seen in 72/76 (94.7%) of patients in the low dose group and 24/27 (88.9%) of patients in the high dose group (P = 0.375). SVR was seen in 60/76 (78.9%) of patients in the low dose group and 25/27 (92.6%) of patients in the high dose group (P = 0.145). Age (Pearson correlation coefficient = 0.263; P = 0.008) and fibrosis (correlation coefficient, 0.263; P = 0.008) showed a significant correlation with the SVR. Conclusion: In patients with genotype 3, peg‐IFN at 1.0 μg/kg/week with ribavirin is as effective as peg‐IFN at 1.5 μg/kg/week with ribavirin.