Infusible platelet membrane microvesicles: a potential transfusion substitute for platelets

BACKGROUND: Several substitutes for intact, viable platelets have been used for transfusion, both to people and in animal models, with varied success. Infusible platelet membrane (IPM) is prepared from human platelets. IPM retains the glycoprotein (GP)lb receptor and has platelet factor 3 activity (procoagulant activity). However, factor V, serotonin, a cytoplasmic marker enzyme (purine nucleotide phosphorylase), GPIIb/IIIa complex, and HLA class I and II antigens are all absent in IPM. STUDY DESIGN AND METHODS: IPM is prepared from outdated platelets. The platelets were disrupted by freezing and thawing; they were washed and heated to inactivate possible viral contaminants, and then the sonicated membrane microvesicle fraction was separated and lyophilized. The hemostatic activity of IPM was measured by its ability to reduce the prolonged bleeding time in thrombocytopenic rabbits. RESULTS: Administration of IPM at a dose of 2 mg per kg results in a substantial reduction in the bleeding time. In a series of 23 experiments, a median preinjection bleeding time of 15 minutes was reduced to 6 minutes within 4 hours after IPM administration. Administration of IPM did show a mild enhancement in the thrombogenicity index, as measured in the Wessler rabbit model. This enhancement is, however, not significant, as a thrombogenicity index value of up to 0.6 is clinically acceptable. CONCLUSION: IPM may have clinical potential as a substitute for platelets in the treatment of bleeding due to thrombocytopenia.     

Prevalence and content analysis of guidelines on handling requests for euthanasia or assisted suicide in Dutch nursing homes

BACKGROUND: The growing number of requests for euthanasia or assisted suicide (EAS) makes it imperative for health care institutions, such as nursing homes, to have written guidelines on how to handle requests for EAS. The objective of this study was to determine the prevalence of EAS guidelines in Dutch nursing homes and to analyze the content. METHODS: Directors of patient care in 324 Dutch nursing homes were asked, by means of a mailed short list of questions, if they had an institutional guideline on EAS and, if so, to provide a copy. Guidelines were analyzed according to a structured list of items based on current jurisprudence, model documents, and opinions of experts. RESULTS: Of the 324 directors, 313 (97%) responded. In 58% of the nursing homes that responded, there existed written guidelines for EAS. Of those guidelines, 74% concerned EAS; in 26%, EAS was integrated in a guideline on terminal care. Of the guidelines, 165 (90%) were based on the policy that EAS is acceptable under specific conditions, and 18 (10%) banned EAS completely. Of the first-mentioned guidelines, 81% described one or more procedures for in-principle objections. In 65% of these guidelines, all official requirements for prudent practice were described. CONCLUSIONS: Despite the rapidly growing number of nursing-home guidelines on EAS and the existence of model documents, there is still considerable variation in the guidelines, and they can be improved in many aspects. A basic prerequisite is that the guidelines include all the official requirements for prudent practice.     

Unconjugated bile salts shuttle through hepatocyte peroxisomes for taurine conjugation

Bile acid-CoA:amino acid N-acyltransferase (BAAT) conjugates bile salts to glycine or taurine, which is the final step in bile salt biosynthesis. In addition, BAAT is required for reconjugation of bile salts in the enterohepatic circulation. Recently, we showed that BAAT is a peroxisomal protein, implying shuttling of bile salts through peroxisomes for reconjugation. However, the subcellular location of BAAT remains a topic of debate. The aim of this study was to obtain direct proof for reconjugation of bile salts in peroxisomes. Primary rat hepatocytes were incubated with deuterium-labeled cholic acid (D(4)CA). Over time, media and cells were collected and the levels of D(4)CA, D(4)-tauro-CA (D(4)TCA), and D(4)-glyco-CA (D(4)GCA) were quantified by liquid chromatography-tandem mass spectrometry (LC/MS/MS). Subcellular accumulation of D(4)-labeled bile salts was analyzed by digitonin permeabilization assays and subcellular fractionation experiments. Within 24 hours, cultured rat hepatocytes efficiently (>90%) converted and secreted 100 μM D(4)CA to D(4)TCA and D(4)GCA. The relative amounts of D(4)TCA and D(4)GCA produced were dependent on the presence of glycine or taurine in the medium. Treatment of D(4)CA-exposed hepatocytes with 30-150 μg/mL digitonin led to the complete release of D(4)CA, D(4)GCA, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) (cytosolic marker). Full release of D(4)TCA, catalase, and BAAT was only observed at 500 μg/mL digitonin, indicating the presence of D(4)TCA in membrane-enclosed organelles. D(4)TCA was detected in fractions of purified peroxisomes, which did not contain D(4)CA and D(4)GCA. Conclusion: We established a novel assay to study conjugation and intra- and transcellular transport of bile salts. Using this assay, we show that cholic acid shuttles through peroxisomes for taurine-conjugation.     

Bezafibrate reduces heart rate and blood pressure in patients with hypertriglyceridemia

OBJECTIVE: In hypertriglyceridemic patients, hypertension occurs frequently and may be associated with hyperinsulinemia and elevated plasma levels of free fatty acids (FFA). Besides the lipid-lowering effects, fibrates have been shown to reduce blood pressure in hypertensive patients. The present study was undertaken to investigate the effects of bezafibrate on hemodynamics in relation to insulin, FFA, sympathetic activity, renal sodium absorption, cyclic-GMP (cGMP) and endothelin-1 in hypertriglyceridemic patients. SUBJECTS AND METHODS: Hypertriglyceridemic patients (17) were randomized to receive in a double-blind placebo-controlled study bezafibrate or placebo for 6 weeks. At the end of both treatment periods, blood pressure and heart rate were measured automatically. Plasma insulin, FFA, aldosterone, catecholamines, cGMP, endothelin-1 levels and 24 h urine catecholamines and sodium excretion were assessed. RESULTS: Bezafibrate therapy decreased serum triglycerides (-65%, P < 0.001) and hemodynamic parameters: heart rate decreased from 69 to 66/min (P = 0.009), systolic blood pressure from 137 to 132 mmHg (P = 0.01), diastolic blood pressure from 81 to 79 mmHg (P = 0.07) and mean blood pressure from 102 to 99 mmHg (P = 0.06). Bezafibrate therapy reduced FFA and insulin (-55 and -57% respectively, both P < 0.001), while sympathetic activity and renal sodium absorption were not affected. cGMP increased (+17%, P = 0.008), whereas endothelin-1 levels tended to decrease upon bezafibrate therapy (-10%, P = 0.077) CONCLUSION: Bezafibrate reduces heart rate, blood pressure, insulin and FFA in hypertriglyceridemic patients. The hemodynamic effects cannot be attributed to changes in sympathetic activity or renal sodium absorption. Instead, based on the increase in plasma cGMP levels, the bezafibrate-induced hemodynamic effects are most likely to be caused by bezafibrate-induced improvement of endothelial function.     

Frequency and characterization of known and novel RHD variant alleles in 37 782 Dutch D‐negative pregnant women

To guide anti‐D prophylaxis, Dutch D‐ pregnant women are offered a quantitative fetal‐RHD‐genotyping assay to determine the RHD status of their fetus. This allowed us to determine the frequency of different maternal RHD variants in 37 782 serologically D‐ pregnant women. A variant allele is present in at least 0·96% of Dutch D‐ pregnant women The D‐ serology could be confirmed after further serological testing in only 54% of these women, which emphasizes the potential relevance of genotyping of blood donors. 43 different RHD variant alleles were detected, including 15 novel alleles (11 null‐, 2 partial D‐ and 2 DEL‐alleles). Of those novel null alleles, one allele contained a single missense mutation (RHD*443C>G) and one allele had a single amino acid deletion (RHD*424_426del). The D‐ phenotype was confirmed by transduction of human D‐ erythroblasts, consolidating that, for the first time, a single amino acid change or deletion causes the D‐ phenotype. Transduction also confirmed the phenotypes for the two new variant DEL‐alleles (RHD*721A>C and RHD*884T>C) and the novel partial RHD*492C>A allele. Notably, in three additional cases the DEL phenotype was observed but sequencing of the coding sequence, flanking introns and promoter region revealed an apparently wild‐type RHD allele without mutations.     

Impact of rectopexy on sexual function: a cohort analysis

Purpose

Laparoscopic ventral rectopexy (LVR) is an established surgical technique for the treatment of both rectal prolapse and symptomatic rectoceles. It is, however, not known whether LVR influences sexual function (SF). The aim of this study was, therefore, to determine the impact of this procedure on the SF of patients.

Methods

All female patients after LVR procedure in a single institution were identified and were sent a questionnaire concerning SF. This addressed sexual activity, satisfaction, preoperative SF, and the impact of surgery on SF. Furthermore, the PISQ-12 validated sexual functioning questionnaire was sent to all female patients.

Results

A total of 217 patients were sent a questionnaire. These patients underwent LVR for rectal prolapse, symptomatic rectocele, or enterocele between 2004 and 2011. Mean age was 62 years (range 22–89). Mean follow-up was 30 months (range 5–83). Response rate was 64 % (139 patients). The number of sexual active patients dropped from 71 to 54 % after surgery. The number of patients being satisfied with their SF remained relatively equal; 91 % of patients before and 85 % of patients after surgery. Forty-three percent of patients stated that the LVR procedure did not influence their sexual function, in 16 % of patients, the procedure positively influenced their SF, and in 13 % of respondents, SF decreased after surgery. The mean PISQ-12 score postoperatively was 34 out of 48.

Conclusions

The impact of LVR on SF of patients seems limited in this cross-sectional study in a large cohort of patients.     

White cell depletion of red cell and pooled random-donor platelet concentrates by filtration and residual lymphocyte subset analysis

This study comparing the relative white cell (WBC)-depleting efficiency of single and double filtration used two filters and new, sensitive, and reliable methods for performing WBC counts on WBC-depleted blood products. A single filtration of red cell (RBC) concentrates with a cotton-wool filter reduced WBC content by 98.64 percent, but the range of residual WBCs was wide, and many filtered units still contained more than the theoretical immunizing dose of 5 to 10 x 10(6) WBCs. A second filtration, however, always produced RBC units that had less than 5 x 10(6) WBCs. Although the degree of WBC depletion observed after a single filtration of a 6-unit pool of random-donor platelet concentrates was greater with a polyester filter than with the cotton-wool filter (98.92 vs. 98.14% reduction, respectively, when mean prefiltration WBC count was less than 600 x 10(6], in both cases, 25 percent of filtered products still contained greater than 5 x 10(6) WBCs; a second filtration (with the cotton-wool filter), however, produced units that were always below the immunizing dose. All double-filtered platelet concentrates had less than 10(6), and one-half had less than 10(4) residual WBCs. Platelet loss was similar with both filters (+/- 16% loss with one filtration). The effectiveness of the filters in producing products that were WBC-depleted below the immunizing dose was dependent on the prefiltration WBC content (but not on the age of the units), and it may be worthwhile to employ methods to ensure that total prefiltration WBC count of the product is less than 400 x 10(6).(ABSTRACT TRUNCATED AT 250 WORDS)     

High levels of carcinoembryonic antigen in a woman with hypothyroidism]

A 53-year-old woman was referred to the outpatient clinic for Internal Medicine, due to an elevated serum concentration of carcinoembryonic antigen (CEA). Hypothyroidism was diagnosed. Following replacement therapy with levothyroxin, the serum concentrations of thyroid stimulating hormone (TSH) and CEA decreased to near-normal levels. No malignancy was found during the remainder of the treatment period. A decreased hepatic clearance of CEA seemed to be the most likely explanation for the observed high CEA concentration in this patient with hypothyroidism. An increased CEA concentration may occur in association with certain malignancies, as well as with non-neoplastic disorders, such as hypothyroidism. As CEA has a low tumour specificity, routine assessment of CEA is not advocated for diagnostic evaluation.