Infantile peripheral neuropathy,deafness, and proximal tubulopathy associated with a novel mutation of the RRM2B gene

Mitochondrial DNA depletion syndromes are a group of autosomal recessive hereditary disorders characterized by reduction of the amount of mitochondrial DNA in the affected tissue (muscle, liver, brain, or kidneys). We report a case of an infant with myopathy, deafness, peripheral neuropathy, nephrocalcinosis, proximal renal tubulopathy, moderate lactic acidosis, and a novel mutation of the RRM2B gene.Mitochondrial DNA depletion syndromes are a group of autosomal recessive hereditary disorders characterized by reduction of the mitochondrial DNA amount in the affected tissue (1). Depletion of mitochondrial DNA can affect specific tissues or combination of organs and tissues including muscles, liver, brain, or kidneys (2,3).Different defects of nuclear genes may lead to different clinical manifestations, such as hepatocerebral syndrome, encephalopathy, or myopathy. One of the recently identified genes for mitochondrial DNA depletion syndromes is RRM2B, which encodes an isoform of a small subunit of ribonucleotide reductase. This enzyme plays an essential role in nucleotide synthesis, converting ribonucleotides to deoxyribonucleotides. Since 2008, 14 mutations of RRM2B gene have been reported (3,4). All the reported mutations are unique and there is no mutation that appears in more than one family (1-4).All reported patients had myopathy and primary lactic acidosis. More than a half of them died before the fourth month of age. The oldest patient with RRM2B mutation was a 42 years old woman with clinical findings suggestive of neurogastrointestinal encephalopathy (5). In this report, we review a case of an infant with muscular hypotonia, myopathy, peripheral neuropathy, deafness, nephrocalcinosis, proximal renal tubulopathy, moderate lactic acidosis, and a novel mutation of the RRM2B gene.     

Revisiting the role of nephrectomy for advanced renovascular disease

BACKGROUND: Despite the advances in antihypertensive therapy and renal revascularization, there remains a group of patients in whom renovascular disease leads to renal atrophy and treatment-resistant hypertension. METHODS: We performed an observational cohort study in which we reviewed blood pressures, renal function, and predictors of response in 74 patients who underwent nephrectomy of a small kidney for uncontrolled hypertension between 1990 and 2000. RESULTS: The median age of the patients was 65 years; 43 (58%) were women. Thirty-five patients (47%) underwent nephrectomy as part of combined revascularization of the contralateral kidney. Associated atherosclerotic diseases were common (28% to 49%), as were prior renal revascularization (21 [28%]) and hypertensive urgency/emergencies (23 [31%]). The mean (+/- SD) long axis of the affected kidney was 8 +/- 2 cm, and the mean function of the kidney (based on radioisotope renography) was 12% +/- 11% of total renal function. The average systolic blood pressure fell from 168 +/- 19 mm Hg to 136 +/- 18 mm Hg (P <0.0001) and diastolic blood pressure declined from 88 +/- 10 mm Hg to 76 +/- 9 mm Hg (P <0.0001) at the most recent available clinic visit (mean follow-up, 4.1 +/- 2.6 years). In addition, the number of antihypertensive medications decreased from 3.2 +/- 1.1 to 2.2 +/- 1.5 (P <0.0001). Renal function remained stable. Results were similar (preoperative blood pressure of 165/88 mm Hg taking three medications to 137/77 mm Hg taking two medications) among the 39 patients who had a nephrectomy without contralateral revascularization. CONCLUSION: Our results suggest that in selected patients with resistant hypertension and renal artery disease that has resulted in atrophic kidneys with reduced function, nephrectomy can improve blood pressure control without further loss in overall renal function.     

Genotype Considerations for Virus-Like Particle-Based Bivalent Norovirus Vaccine Composition

Norovirus (NoV) genogroup I (GI) and GII are responsible for most human infections with NoV. Because of the high genetic variability of NoV, natural infection does not induce sufficient protective immunity to different genotypes or to variants of the same genotype and there is little or no cross-protection against different genogroups. NoV-derived virus-like particles (VLPs) are promising vaccine candidates that induce high levels of NoV-specific humoral and cellular immune responses. It is believed that a bivalent NoV vaccine consisting of a representative VLP from GI and GII is a minimum requirement for an effective vaccine. Here, we compared the abilities of monovalent immunizations with NoV GI.1-2001, GI.3-2002, GII.4-1999, and GII.4-2010 New Orleans VLPs to induce NoV type-specific and cross-reactive immune responses and protective blocking antibody responses in BALB/c mice. All of the VLPs induced comparable levels of type-specific serum IgG antibodies, as well as blocking antibodies to the VLPs used for immunization. However, the abilities of different VLP genotypes to induce cross-reactive IgG and cross-blocking antibodies varied remarkably. Our results confirm previous findings of a lack of cross-protective immune responses between GI and GII NoVs. These data support the rationale for including NoV GI.3 and GII.4-1999 VLPs in the bivalent vaccine formulation, which could be sufficient to induce protective immune responses across NoV genotypes in the two common genogroups in humans.     

Free wall rupture (FWR) in patients with acute ST-elevation myocardial infarction (STEMI) receiving fibrinolytic therapy (FT): a 7-year prospective study

Previous studies have shown a paradoxical increase in early mortality in older patients (>70 years) with acute STEMI treated with fibrinolytic therapy (FT), which has been attributed to the development of free wall rupture (FWR). Our aim was to assess occurrence of FWR in STEMI patients receiving FT. In this 7-year prospective study, data from 1701 consecutive patients were obtained. We analyzed predictors of the in-hospital mortality in patients > 70 years old. The independent contribution of several variables to overall mortality and FWR development was assessed using multiple logistic regression analyses. The mortality of entire cohort was 18% (306/1701). Diabetes mellitus, anterior infarction, smoking, female gender and hypercholesterolemia were independent predictors of in-hospital mortality. FT was given to 18% of all patients (304/1701) of which 13% died (39/304). FWR was 18.4-times more often in patients who received FT. Among patients younger than 70 years who received FT there was no FWR, while in patients ≥70 years of age FWR was found in almost half of the deceased (30/68; 44%). Application of FT in STEMI patients is not associated with higher mortality, but significantly increases number of FWR, especially in patients over 70 years of age.     

Impact of triple pelvic osteotomy on contact stress pressure distribution in the hip joint

Purpose

We studied changes of contact stress distribution in the hip joint after Tonnis triple pelvic osteotomy applied in the treatment of dysplasia and hip joint incongruence in adolescents.

Methods

In a group of 75 patients, 54 (72 %) female, who underwent surgery by triple pelvic osteotomy in adolescence for developmental disorder of the hip and avascular necrosis of the femoral head, a three-dimensional hip joint model was used based on the radiography of the pelvis with hips. The following biomechanical parameters were calculated: resultant hip force normalised to body weight (R/Wb), inclination of the resultant hip force (θ−R), the position of the stress pole (θ), peak contact hip stress (Pmax), and peak contact hip stress normalised to body weight (Pmax/Wb). Gait quality was also assessed.

Results

After surgery the Wiberg CE angle was increased by 17.85° (114 %), resultant hip force normalised to body weight (R/Wb) was decreased by 0.107 (3.3 %), the position of the stress pole was shifted medially by 27.59° (63.5 %), and peak contact hip stress normalised to body weight (Pmax/Wb) was decreased by 2249.74 (55.9 %). Waddling gait was reduced from 17 (23.9 %) to four cases (5.6 %). All changes were statistically highly significant (p<0.01).

Conclusions

The effect of Tonnis triple pelvic osteotomy lies in the improvement of stress distribution across the acetabular cartilage of the hip joint, thus slowing down the degenerative damage of the hip joint.     

Quantitative X-ray Computed Tomography Peritoneography in Malignant Peritoneal Mesothelioma Patients Receiving Intraperitoneal Chemotherapy

Background

Intraperitoneal chemotherapy is used to treat peritoneal surface-spreading malignancies. We sought to determine whether volume and surface area of the intraperitoneal chemotherapy compartments are associated with overall survival and posttreatment glomerular filtration rate (GFR) in malignant peritoneal mesothelioma (MPM) patients.

Methods

Thirty-eight MPM patients underwent X-ray computed tomography peritoneograms during outpatient intraperitoneal chemotherapy. We calculated volume and surface area of contrast-filled compartments by semiautomated computer algorithm. We tested whether these were associated with overall survival and posttreatment GFR.

Results

Decreased likelihood of mortality was associated with larger surface areas (p = 0.0201) and smaller contrast-filled compartment volumes (p = 0.0341), controlling for age, sex, histologic subtype, and presence of residual disease >0.5 cm postoperatively. Larger volumes were associated with higher posttreatment GFR, controlling for pretreatment GFR, body surface area, surface area, and the interaction between body surface area and volume (p = 0.0167).

Discussion

Computed tomography peritoneography is an appropriate modality to assess for maldistribution of intraperitoneal chemotherapy. In addition to identifying catheter failure and frank loculation, quantitative analysis of the contrast-filled compartment’s surface area and volume may predict overall survival and cisplatin-induced nephrotoxicity. Prospective studies should be undertaken to confirm and extend these findings to other diseases, including advanced ovarian carcinoma.

     

In-vivo measurement of LDOPA uptake,dopamine reserve and turnover in the rat brain using [18F]FDOPA PET

Longitudinal measurements of dopamine (DA) uptake and turnover in transgenic rodents may be critical when developing disease-modifying therapies for Parkinson''s disease (PD). We demonstrate methodology for such measurements using [¹⁸F]fluoro-3,4-dihydroxyphenyl-L-alanine ([¹⁸F]FDOPA) positron emission tomography (PET). The method was applied to 6-hydroxydopamine lesioned rats, providing the first PET-derived estimates of DA turnover for this species. Control (n=4) and unilaterally lesioned (n=11) rats were imaged multiple times. Kinetic modeling was performed using extended Patlak, incorporating a k_loss term for metabolite washout, and modified Logan methods. Dopaminergic terminal loss was measured via [¹¹C]-(+)-dihydrotetrabenazine (DTBZ) PET. Clear striatal [¹⁸F]FDOPA uptake was observed. In the lesioned striatum the effective DA turnover increased, shown by a reduced effective distribution volume ratio (EDVR) for [¹⁸F]FDOPA. Effective distribution volume ratio correlated (r>0.9) with the [¹¹C]DTBZ binding potential (BP_ND). The uptake and trapping rate (k_ref) decreased after lesioning, but relatively less so than [¹¹C]DTBZ BP_ND. For normal controls, striatal estimates were k_ref=0.037±0.005 per minute, EDVR=1.07±0.22 and k_loss=0.024±0.003 per minute (30 minutes turnover half-time), with repeatability (coefficient of variation) ≤11%. [¹⁸F]fluoro-3,4-dihydroxyphenyl-L-alanine PET enables measurements of DA turnover in the rat, which is useful for developing novel therapies for PD.