Value of conventional and tissue Doppler echocardiography in the noninvasive measurement of right atrial pressure

Background: Evaluation of right atrial pressure (RAP) provides useful diagnostic, therapeutic, and prognostic information. Aim: To assess the utility of several conventional and tissue Doppler parameters in the estimation of RAP. Methods: Among 50 consecutive patients (median age: 50 years; all in sinus rhythm), invasively measured RAP was simultaneously correlated with pulsed Doppler of tricuspid inflow (peak E and A velocities, E‐wave deceleration time) and pulsed tissue Doppler of lateral tricuspid annulus (peak E’ and A’ velocities, isovolumic relaxation time [IVRT], acceleration time and rate of E’‐wave, deceleration time and rate of E’‐wave). These ratios were calculated: E/A, E’/A’, E/E’, and E/IVRT. Results: The median RAP was 14 mmHg (range 1–27 mmHg) with 29 patients (58%) having an elevated RAP (>10 mmHg). Among all studied Doppler variables, E/E’ ratio showed the strongest correlation with RAP (r = 0.84, P < 0.001) with the following regression equations: RAP = 1.24 + (1.69 × E/E’). The mean difference between Doppler and invasively measured RAP was 0.21 ± 2.6 mmHg. E/ E’ ratio ≥ 4.5 provides 89% sensitivity and 100% specificity for detection of elevated RAP (receiver operating characteristic area 0.95; P < 0.001). Conclusion: Of all echocardiographic variables investigated, tricuspid annular E/E’ ratio is identified as the best index for noninvasive determination of RAP.     

Effect of Multivitamin Supplementation on Measles Vaccine Response among HIV-Exposed Uninfected Tanzanian Infants

Immunization and nutritional interventions are mainstays of child health programs in sub-Saharan Africa, yet few published data exist on their interactions. HIV-exposed (but uninfected) infants enrolled in a randomized placebo-controlled trial of multivitamin supplements (vitamins B complex, C, and E) conducted in Tanzania were sampled for an assessment of measles IgG quantity and avidity at 15 to 18 months. Infants were vaccinated between 8.5 and 12 months of age, and all mothers received high-dose multivitamins as the standard of care. Of 201 HIV-exposed infants who were enrolled, 138 (68.7%) were seropositive for measles. There were no effects of infant multivitamin supplementation on measles seroconversion proportions, IgG concentrations, or IgG avidity (P > 0.05). The measles seroconversion proportion was greater for HIV-exposed infants vaccinated at 10 to 11 months of age than for those vaccinated at 8.5 to 10 months (P = 0.032) and greater for infants whose mothers had a CD4 T-cell count of <200 cells/μl than for infants whose mothers had a CD4 T-cell count of >350 cells/μl (P = 0.039). Stunted infants had a significantly decreased IgG quantity compared to nonstunted infants (P = 0.012). As for measles avidity, HIV-exposed infants vaccinated at 10 to 11 months had increased antibody avidity compared to those vaccinated at 8.5 to 10 months (P = 0.031). Maternal CD4 T-cell counts of <200 cells/μl were associated with decreased avidity compared to counts of >350 cells/μl (P = 0.047), as were lower infant height-for-age z-scores (P = 0.016). Supplementation with multivitamins containing B complex, C, and E does not appear to improve measles vaccine responses for HIV-exposed infants. Studies are needed to better characterize the impact of maternal HIV disease severity on the immune system development of HIV-exposed infants and the effect of malnutrition interventions on vaccine responses. (This study has been registered at ClinicalTrials.gov under registration no. NCT00197730.)     

Characterization of poly-4-hydroxybutyrate mesh for hernia repair applications

Background

Phasix mesh is a fully resorbable implant for soft tissue reconstruction made from knitted poly-4-hydroxybutyrate monofilament fibers. The objectives of this study were to characterize the in vitro and in vivo mechanical and resorption properties of Phasix mesh over time, and to assess the functional performance in a porcine model of abdominal hernia repair.

Materials and methods

We evaluated accelerated in vitro degradation of Phasix mesh in 3 mol/L HCl through 120 h incubation. We also evaluated functional performance after repair of a surgically created abdominal hernia defect in a porcine model through 72 wk. Mechanical and molecular weight (MW) properties were fully characterized in both studies over time.

Results

Phasix mesh demonstrated a significant reduction in mechanical strength and MW over 120 h in the accelerated degradation in vitro test. In vivo, the Phasix mesh repair demonstrated 80%, 65%, 58%, 37%, and 18% greater strength, compared with native abdominal wall at 8, 16, 32, and 48 wk post-implantation, respectively, and comparable repair strength at 72 wk post-implantation despite a significant reduction in mesh MW over time.

Conclusions

Both in vitro and in vivo data suggest that Phasix mesh provides a durable scaffold for mechanical reinforcement of soft tissue. Furthermore, a Phasix mesh surgical defect repair in a large animal model demonstrated successful transfer of load bearing from the mesh to the repaired abdominal wall, thereby successfully returning the mechanical properties of repaired host tissue to its native state over an extended time period.     

Effect of sex steroids on soleus muscle response in hypocalcemic medium (in vitro)

Purpose

Postoperative hypocalcemia is a frequently encountered complication of thyroid surgery. Since hypocalcemic symptoms are closely associated with sex, the aim of this study is to investigate the effects of sex steroids on muscle tissue under hypocalcemic conditions.

Methods

Six groups consisting of control male (M), control female (F), gonadectomized male (M−), gonadectomized female (F−), estradiol-applied gonadectomized male (MX), and testosterone-applied gonadectomized female (FX) rats were used. Contraction recordings were obtained from soleus muscle flaps. Maximal tension (PT), frequency required for 50% of PT (F50), contraction velocity at F50 (V50), and changes in contraction values (d[PT], d[F50], d[V50]) between normocalcemic and hypocalcemic conditions were calculated.

Results

d[PT], d[F50], and d[V50] were significantly higher in M− and MX groups compared with control M group. Whereas d[PT], d[F50], and d[V50] parameters of the F− group were significantly higher than control F group, d[F50] and d[PT] of the FX group showed no significant change and d[V50] for the FX group was significantly lower. A comparison of control groups showed that d[PT], d[F50], and d[V50] of the F group were significantly higher than those of the M group.

Conclusion

Whereas absence of both testosterone and estradiol caused an increase in hypocalcemia-induced changes in contraction parameters of rat skeletal muscle, presence or application of testosterone clearly stabilized contraction parameters.     

African American Renal Transplant Recipients (RTR) Require Higher Tacrolimus Doses to Achieve Target Levels Compared to White RTR: Does Clotrimazole Help?

The number of African Americans (AAs) on the kidney waiting list is increasing in the United States. Several studies showed that AAs are at higher risk for rejection and graft loss. Because of genetic polymorphisms, AAs may metabolize calcineurin inhibitors faster than Caucasian (C) individuals. The goal of this study is to evaluate the tacrolimus (TAC) dose required to reach therapeutic levels and to assess the impact of clotrimazole on TAC metabolism in AAs compared to C patients. One hundred forty-two AA renal transplant recipients (RTRs) were compared to 309 C RTRs. Demographics were similar in both groups. Induction therapy and maintenance immunosuppression were similar in both groups and included TAC, mycophenolate acid (MPA), and steroids. The goal in all RTRs was to maintain a 12-hour trough level of 10 to 15 ng/mL in the first 3 months, 8 to 10 ng/mL for the first year, and 5 to 8 ng/mL thereafter. To achieve these levels, AA RTRs require a significantly higher dosage of TAC compared to C patients (5.9 ± 2.9 vs 3.6 ± 2 mg/d, respectively, P < .0001). By multivariate analysis, TAC dose requirements were not affected by age, gender, MPA or prednisone dose, diabetes, and renal function. Adding clotrimazole (CTM) to the RTR regimen significantly reduced the TAC dose requirements in all RTRs. When CTM was used, the TAC dose requirement was not statistically significantly different between AA and C patients (2.6 ± 1.2 mg/d vs 1.8 ± 1.5 mg/d, P = .07). We conclude that AAs required a higher TAC dose to reach the desired trough level in RTRs compared to C RTRs. The use of CTM eliminates the need for higher doses of TAC in AA RTRs. Thus, CTM may aid AA RTRs in achieving therapeutic TAC levels while reducing drug costs.     

Infusion of low-dose vasopressin improves left ventricular function during separation from cardiopulmonary bypass: a double-blind randomized study

We aimed to investigate whether low-dose vasopressin administered to patients undergoing coronary artery bypass grafting (CABG) surgery with preexisting mild to moderate systolic dysfunction can produce sustained improvement in cardiac function. This double-blind randomized study was conducted in a hospital where a single anesthetic and surgical team performed elective CABG. Twenty patients aged 32-61 years who underwent elective CABG between January 2007 and December 2007 were enrolled in this study. The patients randomly received either vasopressin 0.03 IU/min (Group A) or normal saline (Group B) in equal volume for 60 min after cardiopulmonary bypass (CPB). The cardiac output, cardiac index, stroke volume index, fractional area of contraction and systemic vascular resistance index were significantly higher in Group A than in Group B. Adrenaline (mean dose: 0.06 μg/kg x min-1) was required in seven patients from Group B but in none of the Group A patients on initial separation from CPB (P< 0.05). Of the 10 patients in Group B, five required phenylepherine to maintain the mean arterial pressure (MAP) >65 mmHg, whereas none of the Group A patients required phenylephrine for MAP regulation (P< 0.05). We conclude that Infusion of low-dose vasopressin for patients with mild to moderate left ventricular systolic dysfunction during separation from CPB is beneficial for the postoperative hemodynamic profile, reduces the catecholamine doses required and improves left ventricular systolic function.