Post-translational modification patterns on β-myosin heavy chain are altered in ischemic and nonischemic human hearts

Phosphorylation and acetylation of sarcomeric proteins are important for fine-tuning myocardial contractility. Here, we used bottom-up proteomics and label-free quantification to identify novel post-translational modifications (PTMs) on β-myosin heavy chain (β-MHC) in normal and failing human heart tissues. We report six acetylated lysines and two phosphorylated residues: K34-Ac, K58-Ac, S210-P, K213-Ac, T215-P, K429-Ac, K951-Ac, and K1195-Ac. K951-Ac was significantly reduced in both ischemic and nonischemic failing hearts compared to nondiseased hearts. Molecular dynamics (MD) simulations show that K951-Ac may impact stability of thick filament tail interactions and ultimately myosin head positioning. K58-Ac altered the solvent-exposed SH3 domain surface - known for protein-protein interactions - but did not appreciably change motor domain conformation or dynamics under conditions studied. Together, K213-Ac/T215-P altered loop 1's structure and dynamics - known to regulate ADP-release, ATPase activity, and sliding velocity. Our study suggests that β-MHC acetylation levels may be influenced more by the PTM location than the type of heart disease since less protected acetylation sites are reduced in both heart failure groups. Additionally, these PTMs have potential to modulate interactions between β-MHC and other regulatory sarcomeric proteins, ADP-release rate of myosin, flexibility of the S2 region, and cardiac myofilament contractility in normal and failing hearts.

Genotype and Cardiac Outcomes in Pediatric Dilated Cardiomyopathy

Background

Pediatric dilated cardiomyopathy (DCM) is a well‐known clinical entity; however, phenotype–genotype correlations are inadequately described. Our objective was to provide genotype associations with life‐threatening cardiac outcomes in pediatric DCM probands.

Methods and Results

We performed a retrospective review of children with DCM at a large pediatric referral center (2007–2016), excluding syndromic, chemotherapy‐induced, and congenital heart disease causes. Genetic variants were adjudicated by an expert panel and an independent clinical laboratory. In a cohort of 109 pediatric DCM cases with a mean age at diagnosis of 4.2 years (SD 5.9), life‐threatening cardiac outcomes occurred in 47% (42% heart transplant, 5% death). One or more pathogenic/likely pathogenic variants were present in 40/109 (37%), and 36/44 (82%) of pathogenic/likely pathogenic variants occurred in sarcomeric genes. The frequency of pathogenic/likely pathogenic variants was not different in patients with familial cardiomyopathy (15/33 with family history versus 25/76 with no family history, P=0.21). TTN truncating variants occurred in a higher percentage of children diagnosed as teenagers (26% teenagers versus 6% younger children, P=0.01), but life‐threatening cardiac outcomes occurred in both infants and teenagers with these TTN variants. DCM with left ventricular noncompaction features occurred in 6/6 patients with MYH7 variants between amino acids 1 and 600.

Conclusions

Sarcomeric variants were common in pediatric DCM. We demonstrated genotype‐specific associations with age of diagnosis and cardiac outcomes. In particular, MYH7 had domain‐specific association with DCM with left ventricular noncompaction features. Family history did not predict pathogenic/likely pathogenic variants, reinforcing that genetic testing should be considered in all children with idiopathic DCM.

Genetic correction strategies for Duchenne Muscular Dystrophy and their impact on the heart

Background

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder with early childhood onset characterized by profound loss of muscle strength and associated cardiomyopathy. DMD affects is most often caused by deletions involving single or multiple exons that disrupt the open reading frame of the DMD gene. Mutations causing loss or premature truncation of dystrophin result in dystrophin protein deficiency, which renders the plasma membrane of skeletal myofibers and cardiomyocytes weakened.

Aim of Review

Genetic correction is in use to treat DMD, since several drugs have been already approved which partially restore dystrophin production through the use of antisense oligonucleotides. There are multiple ongoing clinical trials to evaluate the efficacy of treating DMD with micro-dystrophins delivered by adeno-associated viruses. Future approaches entail gene editing to target the single copy of the DMD gene on the X-chromosome. The primary, near-term goal is restoration of skeletal muscle dystrophin, and for some of these treatments, the efficacy in the heart is not fully known. Here, we discuss the anticipated cardiac outcomes of dystrophin-targeted therapies, and how this information informs genomic medicine for cardiomyopathies, especially in childhood.

Key Scientific Concepts of Review

Many genetic treatment strategies are being implemented to treat DMD. Since most preclinical testing has focused on skeletal muscle, there is a gap in knowledge about the expected effects of these approaches on cardiac genetic correction and cardiomyopathy progression in DMD. Additional study is needed.

Anomalous structural dynamics of minimally frustrated residues in cardiac troponin C triggers hypertrophic cardiomyopathy

Cardiac TnC (cTnC) is highly conserved among mammals, and genetic variants can result in disease by perturbing Ca2+-regulation of myocardial contraction. Here, we report the molecular basis of a human mutation in cTnC's αD-helix (TNNC1-p.C84Y) that impacts conformational dynamics of the D/E central-linker and sampling of discrete states in the N-domain, favoring the "primed" state associated with Ca2+ binding. We demonstrate cTnC's αD-helix normally functions as a central hub that controls minimally frustrated interactions, maintaining evolutionarily conserved rigidity of the N-domain. αD-helix perturbation remotely alters conformational dynamics of the N-domain, compromising its structural rigidity. Transgenic mice carrying this cTnC mutation exhibit altered dynamics of sarcomere function and hypertrophic cardiomyopathy. Together, our data suggest that disruption of evolutionary conserved molecular frustration networks by a myofilament protein mutation may ultimately compromise contractile performance and trigger hypertrophic cardiomyopathy.

Epigenetic reprogramming to prevent genetic cardiomyopathy

Mutations in the gene that codes for lamin A/C (LMNA) are a common cause of adult-onset cardiomyopathy and heart failure. In this issue of the JCI, Guénantin and Jebeniani et al. identify impaired cardiomyocyte development and maturation as a prenatal feature in a model of laminopathy. Cardiomyocytes carrying the Lmna point mutation H222P misexpressed genes involved in the epithelial-mesenchymal transition and showed decreased methylation at the fourth lysine of histone H3 (H3K4). Notably, inhibiting lysine-specific demethylase 1 in the LMNA H222P mouse model treated this congenital form of cardiomyopathy and improved survival in utero. These data highlight early epigenomic modifications in lamin A/C-mediated pathology and indicate a unique therapeutic strategy for cardiomyopathy.

Mutation location of HCM-causing troponin T mutations defines the degree of myofilament dysfunction in human cardiomyocytes

BACKGROUND

The clinical outcome of hypertrophic cardiomyopathy patients is not only determined by the disease-causing mutation but influenced by a variety of disease modifiers. Here, we defined the role of the mutation location and the mutant protein dose of the troponin T mutations I79N, R94C and R278C.

METHODS AND RESULTS

We determined myofilament function after troponin exchange in permeabilized single human cardiomyocytes as well as in cardiac patient samples harboring the R278C mutation. Notably, we found that a small dose of mutant protein is sufficient for the maximal effect on myofilament Ca2+-sensitivity for the I79N and R94C mutation while the mutation location determines the magnitude of this effect. While incorporation of I79N and R94C increased myofilament Ca2+-sensitivity, incorporation of R278C increased Ca2+-sensitivity at low and intermediate dose, while it decreased Ca2+-sensitivity at high dose. All three cTnT mutants showed reduced thin filament binding affinity, which coincided with a relatively low maximal exchange (50.5 ± 5.2%) of mutant troponin complex in cardiomyocytes. In accordance, 32.2 ± 4.0% mutant R278C was found in two patient samples which showed 50.0 ± 3.7% mutant mRNA. In accordance with studies that showed clinical variability in patients with the exact same mutation, we observed variability on the functional single cell level in patients with the R278C mutation. These differences in myofilament properties could not be explained by differences in the amount of mutant protein.

CONCLUSIONS

Using troponin exchange in single human cardiomyocytes, we show that TNNT2 mutation-induced changes in myofilament Ca2+-sensitivity depend on mutation location, while all mutants show reduced thin filament binding affinity. The specific mutation-effect observed for R278C could not be translated to myofilament function of cardiomyocytes from patients, and is most likely explained by other (post)-translational troponin modifications. Overall, our studies illustrate that mutation location underlies variability in myofilament Ca2+-sensitivity, while only the R278C mutation shows a highly dose-dependent effect on myofilament function.

Familial Dilated Cardiomyopathy Associated With a Novel Combination of Compound Heterozygous TNNC1 Variants

Familial dilated cardiomyopathy (DCM), clinically characterized by enlargement and dysfunction of one or both ventricles of the heart, can be caused by variants in sarcomeric genes including TNNC1 (encoding cardiac troponin C, cTnC). Here, we report the case of two siblings with severe, early onset DCM who were found to have compound heterozygous variants in TNNC1: p.Asp145Glu (D145E) and p.Asp132Asn (D132N), which were inherited from the parents. We began our investigation with CRISPR/Cas9 knockout of TNNC1 in Xenopus tropicalis, which resulted in a cardiac phenotype in tadpoles consistent with DCM. Despite multiple maneuvers, we were unable to rescue the tadpole hearts with either human cTnC wild-type or patient variants to investigate the cardiomyopathy phenotype in vivo. We therefore utilized porcine permeabilized cardiac muscle preparations (CMPs) reconstituted with either wild-type or patient variant forms of cTnC to examine effects of the patient variants on contractile function. Incorporation of 50% WT/50% D145E into CMPs increased Ca²⁺ sensitivity of isometric force, consistent with prior studies. In contrast, incorporation of 50% WT/50% D132N, which had not been previously reported, decreased Ca²⁺ sensitivity of isometric force. CMPs reconstituted 50–50% with both variants mirrored WT in regard to myofilament Ca²⁺ responsiveness. Sinusoidal stiffness (SS) (0.2% peak-to-peak) and the kinetics of tension redevelopment (k_TR) at saturating Ca²⁺ were similar to WT for all preparations. Modeling of Ca²⁺-dependence of k_TR support the observation from Ca²⁺ responsiveness of steady-state isometric force, that the effects on each mutant (50% WT/50% mutant) were greater than the combination of the two mutants (50% D132N/50% D145E). Further studies are needed to ascertain the mechanism(s) of these variants.

The intrinsically disordered C terminus of troponin T binds to troponin C to modulate myocardial force generation

Aberrant regulation of myocardial force production represents an early biomechanical defect associated with sarcomeric cardiomyopathies, but the molecular mechanisms remain poorly defined. Here, we evaluated the pathogenicity of a previously unreported sarcomeric gene variant identified in a pediatric patient with sporadic dilated cardiomyopathy, and we determined a molecular mechanism. Trio whole-exome sequencing revealed a de novo missense variant in TNNC1 that encodes a p.I4M substitution in the N-terminal helix of cardiac troponin C (cTnC). Reconstitution of this human cTnC variant into permeabilized porcine cardiac muscle preparations significantly decreases the magnitude and rate of isometric force generation at physiological Ca2+-activation levels. Computational modeling suggests that this inhibitory effect can be explained by a decrease in the rates of cross-bridge attachment and detachment. For the first time, we show that cardiac troponin T (cTnT), in part through its intrinsically disordered C terminus, directly binds to WT cTnC, and we find that this cardiomyopathic variant displays tighter binding to cTnT. Steady-state fluorescence and NMR spectroscopy studies suggest that this variant propagates perturbations in cTnC structural dynamics to distal regions of the molecule. We propose that the intrinsically disordered C terminus of cTnT directly interacts with the regulatory N-domain of cTnC to allosterically modulate Ca2+ activation of force, perhaps by controlling the troponin I switching mechanism of striated muscle contraction. Alterations in cTnC-cTnT binding may compromise contractile performance and trigger pathological remodeling of the myocardium.

Structural and functional impact of troponin C-mediated Ca2+ sensitization on myofilament lattice spacing and cross-bridge mechanics in mouse cardiac muscle

Acto-myosin cross-bridge kinetics are important for beat-to-beat regulation of cardiac contractility; however, physiological and pathophysiological mechanisms for regulation of contractile kinetics are incompletely understood. Here we explored whether thin filament-mediated Ca²⁺ sensitization influences cross-bridge kinetics in permeabilized, osmotically compressed cardiac muscle preparations. We used a murine model of hypertrophic cardiomyopathy (HCM) harboring a cardiac troponin C (cTnC) Ca²⁺-sensitizing mutation, Ala8Val in the regulatory N-domain. We also treated wild-type murine muscle with bepridil, a cTnC-targeting Ca²⁺ sensitizer. Our findings suggest that both methods of increasing myofilament Ca²⁺ sensitivity increase cross-bridge cycling rate measured by the rate of tension redevelopment (k_TR); force per cross-bridge was also enhanced as measured by sinusoidal stiffness and I_1,1/I_1,0 ratio from X-ray diffraction. Computational modeling suggests that Ca²⁺ sensitization through this cTnC mutation or bepridil accelerates k_TR primarily by promoting faster cross-bridge detachment. To elucidate if myofilament structural rearrangements are associated with changes in k_TR, we used small angle X-ray diffraction to simultaneously measure myofilament lattice spacing and isometric force during steady-state Ca²⁺ activations. Within in vivo lattice dimensions, lattice spacing and steady-state isometric force increased significantly at submaximal activation. We conclude that the cTnC N-domain controls force by modulating both the number and rate of cycling cross-bridges, and that the both methods of Ca²⁺ sensitization may act through stabilization of cTnC's D-helix. Furthermore, we propose that the transient expansion of the myofilament lattice during Ca²⁺ activation may be an additional factor that could increase the rate of cross-bridge cycling in cardiac muscle. These findings may have implications for the pathophysiology of HCM.

Troponin through the looking-glass: emerging roles beyond regulation of striated muscle contraction

Troponin is a heterotrimeric Ca²⁺-binding protein that has a well-established role in regulating striated muscle contraction. However, mounting evidence points to novel cellular functions of troponin, with profound implications in cancer, cardiomyopathy pathogenesis and skeletal muscle aging. Here, we highlight the non-canonical roles and aberrant expression patterns of troponin beyond the sarcomeric milieu. Utilizing bioinformatics tools and online databases, we also provide pathway, subcellular localization, and protein-protein/DNA interaction analyses that support a role for troponin in multiple subcellular compartments. This emerging knowledge challenges the conventional view of troponin as a sarcomere-specific protein exclusively involved in muscle contraction and may transform the way we think about sarcomeric proteins, particularly in the context of human disease and aging.

Myosin Rod Hypophosphorylation and CB Kinetics in Papillary Muscles from a TnC-A8V KI Mouse Model

The cardiac troponin C (TnC)-A8V mutation is associated with hypertrophic and restrictive cardiomyopathy (HCM and RCM) in human and mice. The residue affected lies in the N-helix, a region known to affect Ca²⁺-binding affinity to the N-terminal domain. Here we report on the functional effects of this mutation in skinned papillary muscle fibers from homozygous knock-in TnC-A8V mice. Muscle fibers from left ventricle were activated at 25°C under the ionic conditions of working cardiomyocytes. The pCa-tension relationship showed a 3× increase in Ca²⁺-sensitivity and a decrease (0.8×) in cooperativity (n_H) in mutant fibers. The elementary steps of the cross-bridge (CB) cycle were investigated by sinusoidal analysis. The ATP study revealed that there is no significant change in the affinity of ATP (K₁) for the myosin head. In TnC-A8V mutant fibers, the CB detachment rate (k₂) and its equilibrium constant (K₂) increased (1.5×). The phosphate study revealed that rate constant of the force-generation step (k₄) decreased (0.5×), reversal step (k_-4) increased (2×), and the phosphate-release step (1/K₅) increased (2×). Pro-Q Diamond staining of the skinned fibers samples revealed no significant changes in total phosphorylation of multiple sarcomeric proteins. Further investigation using liquid chromatography-tandem mass spectrometry revealed hypophosphorylation of the rod domain of myosin heavy chain in TnC-A8V mutant fibers compared to wild-type. Immunoblotting confirmed the results observed in the mass spectrometry analysis. The results suggest perturbed CB kinetics-possibly caused by changes in the α-myosin heavy chain phosphorylation profile-as a novel mechanism, to our knowledge, by which a mutation in TnC can have rippling effects in the myofilament and contribute to the pathogenesis of HCM/RCM.

Propofol sedation using Diprifusor target-controlled infusion in adult intensive care unit patients

This multicentre, non-comparative study investigated the range of target blood propofol concentrations required to sedate 122 adult intensive care patients when propofol was administered using Diprifusor target-controlled infusion systems together with opioid analgesia. Depth of sedation was assessed with a modified Ramsay score and the target blood propofol setting was adjusted to achieve the sedation desired for each patient. A desired level of sedation was achieved for 84% of the sedation period. In postcardiac surgery patients the median time-weighted average propofol target setting was 1.34 microg.ml(-1) (10th - 90th percentiles: 0.79-1.93 microg.ml(-1)). Values in brain injured and general ICU patients were 0.98 (10th - 90th percentiles: 0.60-2.55) microg.ml(-1) and 0.42 (10th - 90th percentiles: 0.16-1.19) microg.ml(-1), respectively. Measured propofol concentrations were generally close to values predicted by the Diprifusor system. Target settings in the range of 0.2-2.0 microg.ml(-1) are proposed for propofol sedation in this setting with titration as required in individual patients.

Use of methoxamine in the resuscitation of epinephrine-resistant electromechanical dissociation

We describe three cases of electromechanical dissociation under anaesthesia that were unresponsive to doses of intravenous epinephrine given according to current Advanced Life Support guidelines, but which responded immediately to the intravenous administration of the pure alpha agonist, methoxamine. We suggest a possible mechanism to explain this finding and review the literature on vasopressor drugs used for cardiopulmonary resuscitation during electromechanical dissociation. An intravenous alpha agonist, such as methoxamine 20 mg, should be considered for any case of cardiac arrest secondary to electromechanical dissociation which is unresponsive to epinephrine given according to current guidelines.

Use of cognitive state predicates by language-impaired children

Two studies of the use of cognitive state predicates by children with specific language impairment (SLI) were conducted. Study I analysed longitudinal language samples collected from 26 children with SLI and 25 children with normal language (NL) development, aged 4;4 and 2;11, respectively, at Time I. Study II analysed samples from SLI children with more severe delays at an earlier language stage. There were 10 SLI children and 10 NL children, aged 4;11 and 2;8, respectively, matched by MLU. All cognitive state predicates were identified using both broad and narrow definitions. In Study 1, the SLI children used cognitive state predicates less frequently than their mental age peers, and with no greater frequency or variety than their younger, language peers. In Study II, children with SLI used more predicates referring to communication events, but there were no further group differences. These findings are discussed as they relate to two current psycholinguistic issues: the possible dissociation of grammar and the lexicon, and the role of language in the development of children's theory of mind.

An alternate MLU calculation: magnitude and variability of effects

This study investigated the effect of removing elliptical question responses, imitative utterances, and single-word Yes/No responses before calculating MLU. Forty-seven language samples from preschoolers with and without language impairment were analyzed. Initial MLUs ranged from 2.0 to 6.5 across both groups. The alternate calculation procedures resulted in an average 18% increase in the MLU index, with individual samples increasing as little as 3% or as much as 49%. The magnitude of the effect was primarily related to discourse properties, although in the SLI group there were secondary relationships to language level and proficiency. The observed variation in the discourse properties of language samples makes the alternate MLU index attractive to clinicians and researchers.

Duodenal obstruction in polycystic kidney disease. Case report and review of the literature

Polycystic kidney disease in a common inherited disorder accounting for 8-10% of cases of end-stage renal disease. The enlarged kidneys often produce pain and hematuria but rarely obstruction of surrounding organs. We report a case of autosomal dominant polycystic kidney disease producing symptomatic duodenal obstruction and malnutrition. Duodenal obstruction should be considered in the differential diagnosis of a patient with polycystic kidney disease and intermittent or persistent nausea and vomiting.

Genotypic characterization of strains of commercial wine yeasts by tetrad analysis

The objective of this work was to use tetrad analysis to define the genotypes of a number of commercially available wine yeasts for a range of characteristics related to wine making. The levels of sporulation and spore viability of 13 wine yeasts were determined. Sporulation was very low in one strain and varied from low to high in the other 12 strains. Spore viability of these 12 strains varied from 0-95% and this range was comparable to a large sample of naturally-occurring wine strains. Colonies from viable spores, predominantly from 4-spored asci, from 11 strains were characterized for the ten traits: homothallism/heterothallism, fermentation of sucrose, galactose, maltose; growth on glycerol (nonfermentable); slow growth on glucose and glycerol; level of sulfide production; copper resistance; putative presence of a recessive lethal mutation (inviability of at least two spores/tetrad); yellow pigment (in colonies) on sugar media. The number of heterozygosities for these ten characteristics varied from zero to seven in 11 strains, and eight strains were genetically distinct. Another three strains, distinct from these eight strains, were identical for the ten characteristics and also equivalent for the levels of sporulation and spore viability. Although these three strains are marketed under different designations, there is a strong probability that they were derived from a common ancestral strain. The genotypic characterization of these 11 strains constitutes an important foundation for their identification and their use in breeding programs.

Meningococcal septicaemia: treatment with protein C concentrate

Meningococcal septicaemia is a devastating disease with the potential to develop severe vascular complications. The incidence in Northern Ireland has risen from 27 cases notified in 1992 to 56 notified in 1997. We describe the first use of protein C concentrate in addition to antithrombin III infusion in the management of a life-threatening case of meningococcal septicaemia in the Regional Intensive Care Unit, Royal Group of Hospitals, Belfast, UK. The rationale and the evidence to support the use of protein C concentrate are discussed. Despite the apparent efficacy and safety of this treatment, subsequent cases of meningococcal septicaemia have not received protein C concentrate due to a lack of availability.

Tolerance of large exchange volumes by peritoneal dialysis patients

Improving clearances on peritoneal dialysis involves either more exchanges, greater fill volume, or both. An increase in the number of exchanges is inconvenient, resulting in noncompliance. Therefore, the best option is to increase the exchange volumes; however, patients are often reluctant for fear of discomfort. We tested the tolerance of 20 patients blinded to randomly sequenced volumes of 2, 2.5, and 3 L, performed incenter by the dialysis nurse. Each patient underwent one to three exchanges with each volume. At the end of a 4-hour dwell, the patient scored discomfort and estimated the infused volume. Only one study exchange was performed each day; the rest of the time, the patient continued his or her usual prescription. Fifteen of the patients (75%) were not able to identify the exchange volumes. Four of the five patients who determined the correct exchange volume for 67% to 78% of the exchanges (P < 0.04 compared with 33% expected by chance) had a body surface area greater than 1.75 m2. Of 123 exchanges, 84% were associated with no discomfort, 10% with mild discomfort, and 6% with moderate discomfort. Patients were not more likely to have discomfort with 3-L compared with lower fill volumes. Peritoneal clearances of creatinine (6.1 v 6.6 v 7.7 mL/min/1.73 m2) and urea nitrogen (7.3 v 8.6 v 9.5 mL/min) were progressively greater with increasing exchange volumes (P < 0.001). We conclude that the majority of small as well as large patients will tolerate 2.5- and 3-L exchange volumes. If encouraged to do so, many patients could tolerate greater exchange volumes than they are presently using. Exchange volumes should be readily increased as residual renal function declines.

Vitamin K deficiency with hemorrhage after kidney and combined kidney-pancreas transplantation

Vitamin K deficiency is a common occurrence in the surgical and intensive care unit population, but its incidence in kidney and combined kidney-pancreas allograft recipients has not been described. We report four patients who received cadaveric kidney or combined kidney-pancreas allografts and subsequently developed significant bleeding associated with deficiency of vitamin K. Their coagulopathy promptly resolved with the parenteral administration of vitamin K. Treatment with vitamin K should be considered in kidney or combined kidney-pancreas allograft recipients with a prolonged prothrombin or partial thromboplastin time during the first postoperative week to avoid hemorrhagic complications.

Hospitalization in peritoneal dialysis patients

Hospitalization rates are declining more rapidly for peritoneal dialysis (PD) than for hemodialysis patients. This has been postulated to be caused in part by lower peritonitis rates. However, the causes of admission have not been reexamined in the setting of declining rates. We prospectively examined our hospitalization rates, causes of admission, and impact of peritonitis on hospitalization in adult PD patients at a single center over a 4-year period. There were 274 admissions in 168 patient-years for a rate of 1.6 admissions and 13.0 hospital days per patient-year. Rates were greater for men (1.8 v 1.5; P = 0.013), patients with diabetes (2.2 v 1.4, P < 0.001), and those with a higher peritoneal equilibration test result. Creatinine clearance and sex were independent predictors in a multivariate analysis. The most common causes for admission were cardiac disease (14.6%) and peritonitis (13.5%). Peritonitis accounted for 0.21 admissions and 2.0 hospital days per patient-year. Thirty percent of the incident patients were admitted during the first 90 days of dialysis. Admissions for dehydration and glucose abnormalities were more common in the first 90 days. Overall admission rates, as well as admission rates for peritonitis, did not change over time, although hospital days per year decreased. Those admitted for peritonitis had higher peritonitis rates, more time on PD, and were more likely to be black. Eighty-one percent of the admissions for peritonitis were caused by Staphylococcus aureus, Streptococcus spp, or gram-negative/fungal peritonitis. Patients with peritonitis caused by Staphylococcus epidermidis were less likely to be admitted than patients with peritonitis caused by other organisms. To conclude, peritonitis remains a common cause of hospitalization, despite low peritonitis rates. To decrease admissions for peritonitis, attention should be focused on preventing peritonitis caused by organisms other than S epidermidis.

Developing profiles of risk for parental abduction of children from a comparison of families victimized by abduction with families litigating custody

This study systematically compared parents in abducting families with families litigating custody. Findings indicate that risks for parental abduction of children are multidetermined by: (1) a heightened concern about very young children being exposed to neglectful, endangering, or criminal environments by the other parent; (2) unsubstantiated allegations of sexual abuse; (3) heightened distrust of and less respect for law and authority; and (4) a reluctance to seek help from the courts. Abducting families were also predominantly socially and economically disadvantaged: parents were less likely to have been married to one another; they had lower incomes, were more poorly educated, and were disproportionately members of minority racial and ethnic groups. The social policy dilemmas of identifying these differences as risk factors are discussed together with suggestions for risk management.

Diabetic nephropathy with concurrent hepatitis C virus infection related membranoproliferative glomerulonephritis

Diabetes mellitus is often complicated by nephropathy with progression to renal failure. Various forms of glomerulonephritis have been associated with diabetes, sometimes resulting in more rapid deterioration in renal function and occasionally dictating alternative management of these patients in attempts to reverse or contain nephrosis or renal failure. We report the occurrence of Type I membranoproliferative glomerulonephritis (MPGN) with hepatitis C virus (HCV) infection in two patients, in association with diabetic nephropathy. One patient had cryoglobulinemia and cryoglobulin deposits in the kidney. A brief review of the literature on glomerulonephritides occurring in patients with diabetes mellitus is also presented. Clinicians should be aware of the possible occurrence of Type I MPGN and cryoglobulinemia in patients with diabetes mellitus and HCV infection with the appropriate history and physical findings. The therapeutic approach to managing patients with two distinct concurrent lesions remains unresolved.

A prospective, randomized trial to compare tacrolimus and prednisone with and without mycophenolate mofetil in patients undergoing renal transplantation: first report

PURPOSE

Between September 20, 1995 and September 20, 1996, 120 patients were entered into a prospective, randomized trial comparing tacrolimus and prednisone with (61) and without (59) 2 gm. mycophenolate mofetil daily to determine whether mycophenolate mofetil was associated with a lower incidence of rejection.

MATERIALS AND METHODS

Mean recipient age plus or minus standard deviation was 50.8+/-14.1 years (range 18.8 to 84.1). Mean donor age was 34.3+/-21.7 years (range 0.01 to 76). Of the donors 18 (15%) were older than 60 years. Mean cold ischemia time was 30.9+/-8.4 hours (range 14.2 to 49). Median followup was 8.6+/-0.5 months.

RESULTS

The 6-month actuarial patient survival was 95%, 92% in the double therapy group and 98% in the triple therapy group (not significant). The 6-month actuarial graft survival was 88%, 84% in the double therapy group and 92% in the triple therapy group (not significant). The overall incidence of rejection and steroid resistant rejection was 34.2 and 4.2%, respectively. There was a strong trend toward less rejection in the mycophenolate mofetil group than in the double therapy group (26.2 versus 42.4%). Crossover was common, and was 42.6% from triple to double therapy and 18.6% from double to triple therapy. The reasons for discontinuation of mycophenolate mofetil were gastrointestinal toxicity, primarily diarrhea, or less commonly hematological toxicity, primarily neutropenia or thrombocytopenia. Gastrointestinal toxicity was ameliorated by separating the doses of tacrolimus and mycophenolate mofetil by 2 to 4 hours, and reducing the dose to 1 gm. daily.

CONCLUSIONS

Mycophenolate mofetil appears to be a useful third agent with tacrolimus in patients undergoing renal transplantation, and is associated with a reduction in the rate of rejection and a low incidence of steroid resistant rejection. There is a high incidence of gastrointestinal toxicity associated with the 2 gm. daily dose but this complication is relatively straightforward to manage.

T-wave amplitude: relationships to phasic RSA and heart period changes

T-Wave Amplitude (TWA) has been suggested as an indicator of sympathetic influence on myocardial performance, but critics have argued that TWA is confounded by parasympathetic influence or that it is a non-specific feature of tachycardia. To help clarify the issue, we examined TWA as a function of parasympathetic activity, using cardiac vagal control as measured by high frequency components of heart period variability (respiratory sinus arrhythmia) and of interbeat intervals (IBI), across several stressful tasks. Sixteen male subjects were exposed to Valsalva, Serial Subtraction and Cold-Pressor tasks. After controlling for between-person variance, it was found that RSA did not contribute to TWA and that IBI contributed dependably to TWA only during the Valsalva maneuver, when heart rate was driven very high. In light of these results, we recommend that TWA continue to be considered a candidate indicator of sympathetic influence on myocardial performance, although caution should be used if heart rate is dramatically elevated.

Propofol and alfentanil total intravenous anaesthesia: a comparison of techniques for major thoracic surgery

BACKGROUND

Previous work has highlighted the disadvantages of propofol as a sole agent for total intravenous anaesthesia (TIVA). This randomised study investigated three combinations of propofol and alfentanil as TIVA for major thoracic surgery.

METHODS

In 73 patients undergoing elective thoracic surgery, anaesthesia was conducted either with sodium thiopentone induction and inhalational maintenance (incorporating isoflurane) or with TIVA using propofol with alfentanil (by infusion at one of two rates or in incremental doses). Vital signs and recovery characteristics were recorded.

RESULTS

There were no significant differences in heart rate or blood pressure between groups during either induction or maintenance. Depth of anaesthesia was controlled satisfactorily in all groups. Recovery characteristics were similar between treatment groups, although there was a trend towards earlier orientation in the group which received the highest infusion rate of alfentanil.

CONCLUSION

Continuous infusions of propofol and alfentanil provide safe and reliable TIVA for major thoracic surgery. TIVA was found to be a satisfactory technique in more elderly patients than previously described. The higher of the two alfentanil infusion rates may result in a better combination of propofol and alfentanil with respect to recovery times than the lower.

Children of Armageddon. Common developmental threats in high-conflict divorcing families

This article traces how parental vulnerability to the feelings of humiliation and loss (inherent in highly conflicted divorce and custody litigation) distorts parenting capacities and parent-child relationships in distinctive ways, putting children at risk for specific kinds of developmental difficulties. Pre-oedipal children often fail to achieve a complete separation from their primary caretakers. Oedipal children, already struggling with separation issues, manifest sexualized anxiety and discomfort with gender identity. By latency, these children present as fragmented within themselves and in relationships with others. Each stage-specific response is discussed and illustrated. It is argued that mental health and legal professionals can use this in-depth understanding of child responses to help parents reframe their disputing agendas in terms of the child's developmental concerns and preoccupations to produce custody settlements that are more protective of the child's best interests.

Cognition and communication: referential strategies used by preschoolers with specific language impairment

Ten children with specific language impairment and 10 children with normal language development were asked to describe objects so that a listener could select them. Each trial targeted two out of a group of three toys. The targeted objects were identical or were similar in size or color. Children in the two groups did not differ in referential success, although children in both groups found the size items more difficult. Content analysis of the messages did reveal differences in the referential strategies used most frequently. Children with specific language impairment were more likely to mention the attributes of each object separately, rather than to describe the characteristics common to a pair of objects. Children in both groups talked about separate objects more often when talking about size than about color or object type. Use of this strategy could indicate the effects of attentional capacity on children's solutions to communication tasks.

Acute renal failure in recipients of organ transplantation and nontransplantation patients: comparison of characteristics and mortality

Mortality from acute renal failure in critically ill patients remains in excess of 50% despite decades of improvement in supportive care. It is not known whether replacement of other failing organs by non-renal organ transplantation affects mortality in acute renal failure. We retrospectively reviewed the course of 169 patients with acute renal failure managed at a single university medical center over a 1-year period. Measures of disease severity (need for renal replacement therapy, mechanical ventilation or parenteral nutrition, presence of oliguria and APACHE II scores) and final outcome were compared in 97 patients with acute renal failure who did not receive transplants and 72 patients with acute renal failure who underwent non-renal solid organ transplants. Overall mortality was 50.3% and directly correlated with APACHE II score. Compared to nontransplant patients, transplant recipients were younger. more frequently male, and less often oliguric; but the groups were similar in mean APACHE II scores and need for renal replacement therapy, prolonged mechanical ventilation, and parenteral nutrition. Overall, mortality was significantly lower for transplant patients compared to nontransplant patients (34.7% vs. 61.9%, p < 0.05). In nonoliguric acute renal failure and renal failure not requiring renal replacement therapy, mortality was low and similar in both transplant and nontransplant patients. Compared to nontrasplant patients with similar risk factors and similar APACHE II scores, mortality was significantly lower for transplant patients who were oliguric, or who required renal replacement therapy, mechanical ventilation, or parenteral nutrition. Organ transplantation is associated with a survival advantage in acute renal failure when compared to the outcome of critically ill nontransplant patients. The relation between APACHE II scores and survival is altered by transplantation.

Peritonitis influences mortality in peritoneal dialysis patients

Mortality remains high in peritoneal dialysis (PD) patients. Known risk factors for mortality include age, diabetes, race, initial albumin level, and cardiovascular disease. Peritonitis is reported to cause death in 1 to 6% of PD patients but has not been well studied as a risk factor for mortality. This study examined 516 adults with a total of 896 yr on PD at one center to determine if peritonitis influenced mortality. Time at risk began on Day 1 of training and ended at death, transplant, or 60 days after transfer to hemodialysis or intermittent peritoneal dialysis. The overall mortality rate was 17.4/100 patient yr. Survival was lower for whites, men, diabetic patients, and older patients. Independent risk factors for mortality (by Cox proportional hazards) were race, diabetes, increased age, and increased peritonitis rate. Use of the Y-set was not associated with decreased mortality. Peritonitis was a risk factor only in whites, nondiabetic patients, and those patients over the age of 60. For every 0.5/yr increase in the peritonitis rate, the risk of death increased 10% in whites, 11% in those patients who were over the age of 60, and 4% for nondiabetic patients. Mortality rates did not decrease over time (1979 to 1995), although peritonitis rates fell significantly (P < 0.001). Rates of Gram-negative and fungal peritonitis showed no trend over time. Peritonitis contributed to 25 of 158 (15.8%) of deaths. Gram-negative/fungal peritonitis accounted for 14 deaths (9.5% of all Gram-negative/fungal episodes) whereas Staphylococcus epidermidis accounted for only 1 death (0.5% of all S. epidermidis episodes) (P < 0.001). Cardiovascular disease was more common in those patients whose deaths were unrelated to peritonitis (P < 0.01), whereas an infectious cause was more common in those patients whose deaths were peritonitis-related (P < 0.001). In this study, peritonitis was a risk factor for death in whites, nondiabetic patients, and older patients. However, the Y-set did not improve survival, perhaps because it does not decrease Gram-negative/fungal peritonitis. To have an impact on survival, efforts are needed to reduce the peritonitis that results from these more serious pathogens.

A randomized trial of Staphylococcus aureus prophylaxis in peritoneal dialysis patients: mupirocin calcium ointment 2% applied to the exit site versus cyclic oral rifampin

The objective of this study was to compare prophylaxis for Staphylococcus aureus infections in peritoneal dialysis patients using 600 mg cyclic oral rifampin for 5 days every 3 months versus mupirocin calcium ointment 2% applied daily to the exit site. The study design was a prospective randomized trial, controlling for S aureus nasal carriage. Eighty-two continuous ambulatory and continuous cyclic peritoneal dialysis patients (54% male, 71 % white, 34% insulin-dependent, mean prestudy time on peritoneal dialysis 1.2 years) were randomly assigned to cyclic rifampin (n = 41 patients) or daily exit site mupirocin prophylaxis (n = 41 patients). Mean follow-up was 1 year. S aureus catheter infection rates were 0.13/yr with mupirocin and 0.15/yr with rifampin (P = NS). Both rates were significantly lower than the center's historical rate (the period between 1983 and 1992) of 0.46/yr prior to the study (P < 0.001). S aureus peritonitis rates were 0.04/yr with mupirocin and 0.02/yr with rifampin (P = NS), both significantly lower than the center's historical rate of 0.16/yr (P < 0.02). Catheter loss due to S aureus infections was 0.02/yr with mupirocin and 0/yr with rifampin (P = NS), both significantly lower than the center's historical rate of 0.12/yr (P < 0.001). There were no side effects in patients using mupirocin, but 12% were unable to continue rifampin due to side effects. We conclude that mupirocin ointment at the exit site and cyclic oral rifampin are equally effective in reducing S aureus catheter infections. In addition, rifampin or mupirocin significantly reduced S aureus peritonitis and catheter loss due to S aureus infections. Mupirocin at the exit site provides an excellent alternative prophylaxis for S aureus infections, particularly in patients who cannot tolerate oral rifampin therapy.

Pain relief for thoracotomy. Comparison of morphine requirements using an extrapleural infusion of bupivacaine

BACKGROUND AND OBJECTIVES

The effectiveness of a continuous infusion of extrapleural bupivacaine for relief of postoperative pain was assessed in patients undergoing posterolateral thoracotomy under general anesthesia by comparing morphine requirements.

METHODS

Bupivacaine 0.25% was infused at a rate of 5 mL/h through an unkinkable extrapleural catheter that was sited under direct vision at operation.

RESULTS

Mean (+/- SD) 24-hour requirements for morphine from a patient-controlled analgesia device were 39 +/- 15 mg for the treated group and 69 +/- 26 mg in the control group (P < .006). Patients in the treated group recorded significantly smaller visual analog scores for pain both at rest (P < .005) and on movement (P < .03) compared to the control group. There were no adverse effects associated with the use of extrapleural bupivacaine in this study.

CONCLUSIONS

Continuous extrapleural infusion of bupivacaine through unkinkable catheters sited during thoracotomy resulted in decreased intravenous patient-controlled analgesia use and decreased verbal categoric pain scores at rest and during movement.

Clinical interventions with latency-age children of high conflict and violence

Children who live in divorced families where conflict is high are often witness to intermittent or frequent verbal or physical aggression between their parents. A theoretical framework and a group treatment model with case vignettes are presented for understanding and intervening with latency-age children of such parents.

High-conflict divorce

This article reviews available research studies of high-conflict divorce and its effects on children. Interparental conflict after divorce (defined as verbal and physical aggression, overt hostility, and distrust) and the primary parent's emotional distress are jointly predictive of more problematic parent-child relationships and greater child emotional and behavioral maladjustment. As a group, children of high-conflict divorce as defined above, especially boys, are two to four times more likely to be clinically disturbed in emotions and behavior compared with national norms. Court-ordered joint physical custody and frequent visitation arrangements in high-conflict divorce tend to be associated with poorer child outcomes, especially for girls. Types of intervention programs and social policy appropriate for these kinds of families are presented.

Conversations with children who are language impaired: asking questions

Samples of conversational language were elicited with a standardized interview protocol from 24 children, aged 2:6 to 7:8, half with specific language impairment (SLI), half with normally developing language (LN), matched for language level. Samples were analyzed to determine whether there were associations between adult questioning and children's use of ellipsis. For the SLI children, but not the LN children, increased proportions of questions were significantly correlated to increased proportions of ellipsis. This finding has implications for the use of MLU measures in clinical and research practice.

A clinical typology of interparental violence in disputed-custody divorces

From two studies of high-conflict divorcing families in child custody disputes, four characteristic profiles of interparental violence were identified: ongoing or episodic battering by males, female-initiated violence, interactive violence controlled by males, and violence engendered by separation or postdivorce trauma. A fifth profile, culled from a subsample of members of the first two groups, was characterized by psychotic and paranoid reactions.

Relation between mental age and vocabulary development among children with mild mental retardation

An investigation of the relation between lexical knowledge and mental age (MA) in elementary school-age children with mild mental retardation was conducted. Lexical knowledge was assessed using the Peabody Picture Vocabulary Test-Revised (PPVT-R) and the Boehm Test of Basic Concepts. Items on the PPVT-R focus on labels for objects and events; items on the Boehm focus on relational terms. Mental age was measured via the Columbia Mental Maturity Scale. Results indicated that the relation between lexical knowledge and MA depended upon the nature of the vocabulary test: The correlation between the Boehm and MA was significantly higher than that between the PPVT-R and MA, suggesting that for this population, MA is more strongly related to knowledge of abstract relational terms than to knowledge of labels for objects and events. The latter may be more open to the influence of differential language experience.

Hemoperitoneum complicating chronic peritoneal dialysis: single-center experience and literature review

Hemoperitoneum is a well-recognized, if uncommon, complication of chronic peritoneal dialysis. In this review of 424 patients maintained on peritoneal dialysis at a single center during an 11-year period, 26 patients (6.1%) developed one or more episodes of hemoperitoneum. Three patients had hemoperitoneum on two separate occasions with different etiologies. One additional patient was seen on a hospital consultative service. Three types of bleeding episodes were observed. Twenty-one of 30 (70%) were benign, consisting of pink-tinged dialysate with little clinical consequence (group 1). Three (10%) consisted of minor hemoperitoneum associated with significant intra-abdominal pathology (group 2), and six (20%) required active intervention (group 3). The most frequent cause of hemoperitoneum was bleeding related to menstruation or ovulation; hemoperitoneum was more common in women than in men. Two patients had hemoperitoneum occurring after more than 6 years on dialysis. In both, the etiology was sclerosing peritonitis, an association not previously noted. The less common etiologies of hemoperitoneum encountered in our patients were similar to those in reports from other centers and are compiled here.

Calcium mass transfer in peritoneal dialysis patients using 2.5 mEq/l calcium dialysate

Standard peritoneal dialysate has a relatively high calcium concentration of 3.5 mEq/l. Peritoneal dialysis patients thus gain calcium from the dialysate which contributes to the risk of hypercalcemia. Dialysate with 2.5 mEq/l calcium is now available. Theoretically, using dialysate with this calcium content, calcium transfer should be negative (from the patient into the dialysate) when the patient is hypercalcemic, and positive when the patient is normocalcemic or hypercalcemic. Thus, 2.5 mEq/l calcium dialysate may allow larger doses of calcium carbonate to be prescribed. We compared calcium mass transfer (CMT) in 17 stable peritoneal dialysis patients using 3.5 and 2.5 mEq/l calcium dialysate. A solution of 2.05 l, 1.5 g/dl dextrose was dwelled for 4 hours. Calcium was measured in the drained dialysate and serum (total and ionized). Mean CMT was 0.7 +/- 0.5 mEq/exchange using 3.5 mEq/l calcium dialysate and -0.9 +/- 0.9 mEq/exchange using 2.5 mEq/l calcium dialysate (p less than 0.0001). At the time of the CMT studies, the mean serum ionized calcium levels were identical for the two groups (2.6 mEq/l). CMT correlated inversely with serum total calcium, serum ionized calcium, and drained dialysate volume. During hypercalcemia calcium transfer was from the dialysate to the patient when 3.5 mEq/l calcium dialysate was used, but from the patient to the dialysate when 2.5 mEq/l calcium dialysate was used. We conclude that 2.5 mEq/l calcium dialysate is effective in removing calcium and will be helpful in preventing hypercalcemia when large doses of oral calcium compounds are prescribed as a phosphate binder.

Iatrogenic hypercalcemia in hemodialysis patients

Calcium carbonate is frequently used in large doses as a phosphorus binder in hemodialysis patients, which often results in hypercalcemia. In most studies in which calcium carbonate is prescribed to control serum phosphorus levels the patients are not given calcitriol. However, calcitriol may be necessary for suppression of parathyroid hormone. The risk of hypercalcemia when calcium supplements are used in conjunction with calcitriol has not previously been examined in detail. We reviewed the charts of 74 hemodialysis patients (119 patient dialysis years) to determine the relationship of serum calcium to calcitriol, calcium therapy, and PTH levels. Twenty-eight patients (38%) were hypercalcemic at some point. Calcitriol therapy significantly increased the risk of hypercalcemia, independently of calcium therapy (p = 0.032). However, patients on a low dose of calcitriol were more than twice as likely to be hypercalcemic than patients on higher doses. Mean PTH levels were lower in the patients on the lower doses of calcitriol, indicating less severe hyperparathyroid disease. We conclude that hypercalcemia is a common complication in hemodialysis patients on calcitriol and calcium carbonate. Whether lowering the dialysate calcium, as suggested by other investigators, will successfully decrease the risk of hypercalcemia without worsening hyperparathyroidism remains to be determined.