The differentiation of delayed hemolytic and delayed serologic transfusion reactions: incidence and predictors of hemolysis

BACKGROUND: After differentiation of the entities of clinically detectable delayed hemolytic (DHTR) and delayed serologic transfusion reactions (DSTR), previous investigators calculated a DHTR:DSTR incidence ratio of 18:72 from a retrospective review of patients with serologic evidence of DHTR or DSTR. There are no published data on factors that may influence the occurrence of DHTR versus DSTR in a given patient. STUDY DESIGN AND METHODS: Retrospective review was conducted of 292 patients at the Mayo Clinic who, between 1980 and 1992, received a clinical diagnosis of DHTR or DSTR concurrently with a serologic diagnosis. Red cell alloantibody specificity, the activity of the patient's reticuloendothelial system, and concurrent immunosuppression were evaluated as potential predictors of the occurrence of DHTR versus DSTR in different patients. RESULTS: The incidence of DHTR or DSTR was 1 in 1899 allogeneic red cell units transfused, with a DHTR:DSTR ratio of 36:64. Alloantibody specificity was the only variable that affected the occurrence of DHTR versus DSTR at the clinical level, with the anti-Jka and anti-Fya specificities, as well as multiple coexisting specificities, significantly associated with detectable hemolysis (p < 0.05). CONCLUSION: Clinically detectable DHTRs are found to occur more commonly than previously believed when the clinical and serologic diagnoses are made concurrently and appropriate work-ups for hemolysis are ordered. The association of certain alloantibody specificities with detectable DHTRs may have implications for clinical transfusion practice.     

Effect of dialysate calcium concentrations on intradialytic blood pressure course in cardiac-compromised patients

To prevent hypercalcemia in the treatment of secondary hyperparathyroidism, low calcium (L-Ca) dialysate is advocated. However, changes in ionized calcium (i-Ca) levels have a pivotal role in myocardial contraction and could influence blood pressure stability during dialysis. Recently, our group found in patients with normal cardiac function a significant decrease in blood pressure (decrease in systolic blood pressure [DSBP]: -13 mm Hg and decrease in mean arterial pressure [DMAP]: -7 mm Hg) during dialysis with L-Ca dialysate compared with high calcium (H-Ca) dialysate, and this was mainly related to a decreased left ventricular contractility with use of L-Ca dialysate. On the basis of these data, it could be expected that changes in i-Ca levels during dialysis are of more clinical importance in cardiac-compromised patients (CCpts), New York Heart Association classifications III and IV. In this study, the effects of L-Ca dialysate (1.25 mmol/L) and H-Ca dialysate (1.75 mmol/L) on arterial blood pressure parameters (systolic [SBP], diastolic [DBP], and mean arterial blood pressure [MAP]), heart rate, stroke distance (SDist), and minute distance (MDist) during 3 hours of a standardized ultrafiltration/hemodialysis (UF+HD) in nine CCpts was investigated. i-Ca levels increased significantly with H-Ca dialysate UF+HD, whereas there was no change with L-Ca dialysate. SBP, DBP, and MAP decreased statistically and clinically significantly during UF+HD with L-Ca dialysate and were significantly lower with the use of L-Ca dialysate compared with H-Ca dialysate. SDist and MDist decreased significantly with L-Ca dialysate, whereas there were no changes in SDist and MDist with H-Ca dialysate. The predialysis and postdialysis index of systemic vascular resistance (SVRI) was similar between L-Ca dialysate and H-Ca dialysate use. Between the two groups, there were no significant differences in changes in SVRI. From this study, we can conclude that changes in i-Ca levels are a very important determinant of the blood pressure response during UF+HD in CCpts, and this response is mediated by changes in myocardial contractility.     

Measurement of renin in segmental renal veins of hypertensives

In 27 of 270 patients studies for possible renovascular hypertension, a lesion affecting a segmental renal artery was seen on angiography. In 22 patients who had sufficient data, the significance of measuring segmental-renal-vein renin in the diagnosis and treatment of segmental disease was evaluated. In 11 (50%), the renin values of segmental vessels supported the clinical diagnosis. In four (36%) of these 11, a high-renin-release area would not have been identified without the stress of upright posture. Successful treatment of hypertension was achieved in six of nine patients who had a revascularization procedure or resection of the segmental vessels. Samples from involved and uninvolved segments of the kidney as well as from the contralateral renal vein and inferior vena cava, together with the stimuli of sodium and volume depletion augmented by upright posture, enabled confirmation of the angiographic diagnosis of segmental-renovascular hypertension.     

Association between genetic variants in key vitamin-D-pathway genes and external apical root resorption linked to orthodontic treatment

This study evaluated the association between single-nucleotide polymorphisms (SNPs) in vitamin-D-related genes and the amount of external apical root resorption linked to orthodontic treatment. One hundred and forty-three individuals were assessed. The amount of external apical root resorption of upper central incisors (EARR_inc) and lower first molars (EARR_mol) were evaluated in radiographs. Seven SNPs were genotyped across four genes including the vitamin D receptor [VDR], group-specific component [GC], cytochrome P450 family 27 subfamily B member 1 [CYP27B1], and cytochrome P450 family 24 subfamily A member 1 [CYP24A1]. Linear regressions were implemented to determine allele-effects on external apical root resorption. Individuals carrying the AA genotype in VDR rs2228570 had a 21% higher EARR_mol than those having AG and GG genotypes (95% CI: 1.03,1.40). EARR_mol in heterozygous rs2228570, was 12% lower than for homozygotes (95%CI: 0.78,0.99). Participants with the CCG haplotype (rs1544410-rs7975232-rs731236) in VDR had an EARR_mol 16% lower than those who did not carry this haplotype. Regarding CYP27B1 rs4646536, EARR_inc in participants who had at least one G allele was 42% lower than for homozygotes AA (95%CI: 0.37,0.93). Although these results did not remain significant after multiple testing adjustment, potential associations may still be suggested. Further replication studies are needed to confirm or refute these findings.