Cardiac output measurement from arterial pressure waveforms presumes a defined relationship between the arterial pulse pressure (PP), vascular compliance (C), and resistance (R). Cardiac output ...estimates degrade if these assumptions are incorrect. We hypothesized that sepsis would differentially alter central and peripheral vasomotor tone, decoupling the usual pressure wave propagation from central to peripheral sites. We assessed arterial input impedance (Z), C, and R from central and peripheral arterial pressures, and aortic blood flow in an anesthetized porcine model (n = 19) of fluid resuscitated endotoxic shock induced by endotoxin infusion (7 μg·kg⁻¹·h⁻¹ increased to 14 and 20 μg·kg⁻¹·h⁻¹ every 10 min and stopped when mean arterial pressure <40 mmHg or Sv(O₂) < 45%). Aortic, femoral, and radial artery pressures and aortic and radial artery flows were measured. Z was calculated by FFT of flow and pressure data. R and C were derived using a two-element Windkessel model. Arterial PP increased from aortic to femoral and radial sites. During stable endotoxemia with fluid resuscitation, aortic and radial blood flows returned to or exceeded baseline while mean arterial pressure remained similarly decreased at all three sites. However, aortic PP exceeded both femoral and radial arterial PP. Although Z, R, and C derived from aortic and radial pressure and aortic flow were similar during baseline, Z increases and C decreases when derived from aortic pressure whereas Z decreases and C increases when derived from radial pressure, while R decreased similarly with both pressure signals. This central-to-peripheral vascular tone decoupling, as quantified by the difference in calculated Z and C from aortic and radial artery pressure, may explain the decreasing precision of peripheral arterial pressure profile algorithms in assessing cardiac output in septic shock patients and suggests that different algorithms taking this vascular decoupling into account may be necessary to improve their precision in this patient population.
Congenital disorders of glycosylation (CDGs) form a genetically and clinically heterogeneous group of diseases with aberrant protein glycosylation as a hallmark. A subgroup of CDGs can be attributed ...to disturbed Golgi homeostasis. However, identification of pathogenic variants is seriously complicated by the large number of proteins involved. As part of a strategy to identify human homologs of yeast proteins that are known to be involved in Golgi homeostasis, we identified uncharacterized transmembrane protein 199 (TMEM199, previously called C17orf32) as a human homolog of yeast V-ATPase assembly factor Vph2p (also known as Vma12p). Subsequently, we analyzed raw exome-sequencing data from families affected by genetically unsolved CDGs and identified four individuals with different mutations in TMEM199. The adolescent individuals presented with a mild phenotype of hepatic steatosis, elevated aminotransferases and alkaline phosphatase, and hypercholesterolemia, as well as low serum ceruloplasmin. Affected individuals showed abnormal N- and mucin-type O-glycosylation, and mass spectrometry indicated reduced incorporation of galactose and sialic acid, as seen in other Golgi homeostasis defects. Metabolic labeling of sialic acids in fibroblasts confirmed deficient Golgi glycosylation, which was restored by lentiviral transduction with wild-type TMEM199. V5-tagged TMEM199 localized with ERGIC and COPI markers in HeLa cells, and electron microscopy of a liver biopsy showed dilated organelles suggestive of the endoplasmic reticulum and Golgi apparatus. In conclusion, we have identified TMEM199 as a protein involved in Golgi homeostasis and show that TMEM199 deficiency results in a hepatic phenotype with abnormal glycosylation.
Background and Aims
Vacuolar H+‐ATP complex (V‐ATPase) is a multisubunit protein complex required for acidification of intracellular compartments. At least five different factors are known to be ...essential for its assembly in the endoplasmic reticulum (ER). Genetic defects in four of these V‐ATPase assembly factors show overlapping clinical features, including steatotic liver disease and mild hypercholesterolemia. An exception is the assembly factor vacuolar ATPase assembly integral membrane protein (VMA21), whose X‐linked mutations lead to autophagic myopathy.
Approach and Results
Here, we report pathogenic variants in VMA21 in male patients with abnormal protein glycosylation that result in mild cholestasis, chronic elevation of aminotransferases, elevation of (low‐density lipoprotein) cholesterol and steatosis in hepatocytes. We also show that the VMA21 variants lead to V‐ATPase misassembly and dysfunction. As a consequence, lysosomal acidification and degradation of phagocytosed materials are impaired, causing lipid droplet (LD) accumulation in autolysosomes. Moreover, VMA21 deficiency triggers ER stress and sequestration of unesterified cholesterol in lysosomes, thereby activating the sterol response element‐binding protein–mediated cholesterol synthesis pathways.
Conclusions
Together, our data suggest that impaired lipophagy, ER stress, and increased cholesterol synthesis lead to LD accumulation and hepatic steatosis. V‐ATPase assembly defects are thus a form of hereditary liver disease with implications for the pathogenesis of nonalcoholic fatty liver disease.
To measure the relationship between blood flow and central venous pressure (Pcv) and to estimate mean systemic filling pressure (Pmsf), circulatory compliance, and stressed volume in patients in the ...intensive care unit.
Intervention study.
Intensive care unit of a university hospital.
Twelve mechanically ventilated postoperative cardiac surgery patients.
Inspiratory holds were performed during normovolemia in supine position (baseline), relative hypovolemia by placing the patients in 30 degree head-up position (hypo), and relative hypervolemia by volume loading with 0.5 L colloid (hyper).
We measured the relationship between blood flow and Pcv using 12-second inspiratory-hold maneuvers transiently increasing Pcv to three different steady-state levels and monitored the resultant blood flow via the pulse contour method during the last 3 seconds. The Pcv to blood flow relation was linear for all measurements with a slope unaltered by relative volume status. Pmsf decreased with hypo and increased with hyper (18.8 +/- 4.5 mm Hg, to 14.5 +/- 3.0 mm Hg, to 29.1 +/- 5.2 mm Hg baseline, hypo, hyper, respectively, p < 0.05). Baseline total circulatory compliance was 0.98 mL x mm Hg x kg and stressed volume was 1677 mL.
Pmsf can be determined in intensive care patients with an intact circulation with use of inspiratory pause procedures, making serial measures of circulatory compliance and circulatory stressed volume feasible.
A decade ago, it became possible to derive mean systemic filling pressure (MSFP) at the bedside using the inspiratory hold maneuver. MSFP has the potential to help guide hemodynamic care, but the ...estimation is not yet implemented in common clinical practice. In this study, we assessed the ability of MSFP, vascular compliance (Csys), and stressed volume (Vs) to track fluid boluses. Second, we assessed the feasibility of implementation of MSFP in the intensive care unit (ICU). Exploratory, a potential difference in MSFP response between colloids and crystalloids was assessed.
This was a prospective cohort study in adult patients admitted to the ICU after cardiac surgery. The MSFP was determined using 3-4 inspiratory holds with incremental pressures (maximum 35 cm H
O) to construct a venous return curve. Two fluid boluses were administered: 100 and 500 ml, enabling to calculate Vs and Csys. Patients were randomized to crystalloid or colloid fluid administration. Trained ICU consultants acted as study supervisors, and protocol deviations were recorded.
A total of 20 patients completed the trial. MSFP was able to track the 500 ml bolus (
< 0.001). In 16 patients (80%), Vs and Csys could be determined. Vs had a median of 2029 ml (IQR 1605-3164), and Csys had a median of 73 ml mmHg
(IQR 56-133). A difference in response between crystalloids and colloids was present for the 100 ml fluid bolus (
= 0.019) and in a post hoc analysis, also for the 500 ml bolus (
= 0.010).
MSFP can be measured at the bedside and provides insights into the hemodynamic status of a patient that are currently missing. The clinical feasibility of Vs and Csys was judged ambiguously based on the lack of required hemodynamic stability. Future studies should address the clinical obstacles found in this study, and less-invasive alternatives to determine MSFP should be further explored.
ClinicalTrials.gov Identifier NCT03139929.
Disorders of Golgi homeostasis form an emerging group of genetic defects. The highly heterogeneous clinical spectrum is not explained by our current understanding of the underlying cell-biological ...processes in the Golgi. Therefore, uncovering genetic defects and annotating gene function are challenging. Exome sequencing in a family with three siblings affected by abnormal Golgi glycosylation revealed a homozygous missense mutation, c.92T>C (p.Leu31Ser), in coiled-coil domain containing 115 (CCDC115), the function of which is unknown. The same mutation was identified in three unrelated families, and in one family it was compound heterozygous in combination with a heterozygous deletion of CCDC115. An additional homozygous missense mutation, c.31G>T (p.Asp11Tyr), was found in a family with two affected siblings. All individuals displayed a storage-disease-like phenotype involving hepatosplenomegaly, which regressed with age, highly elevated bone-derived alkaline phosphatase, elevated aminotransferases, and elevated cholesterol, in combination with abnormal copper metabolism and neurological symptoms. Two individuals died of liver failure, and one individual was successfully treated by liver transplantation. Abnormal N- and mucin type O-glycosylation was found on serum proteins, and reduced metabolic labeling of sialic acids was found in fibroblasts, which was restored after complementation with wild-type CCDC115. PSI-BLAST homology detection revealed reciprocal homology with Vma22p, the yeast V-ATPase assembly factor located in the endoplasmic reticulum (ER). Human CCDC115 mainly localized to the ERGIC and to COPI vesicles, but not to the ER. These data, in combination with the phenotypic spectrum, which is distinct from that associated with defects in V-ATPase core subunits, suggest a more general role for CCDC115 in Golgi trafficking. Our study reveals CCDC115 deficiency as a disorder of Golgi homeostasis that can be readily identified via screening for abnormal glycosylation in plasma.
Purpose
Ambulatory peripheral vascular interventions have been steadily increasing. In ambulatory procedures, 4F devices might be particularly useful having the potential to reduce access-site ...complications; however, further evidence on their safety and efficacy is needed.
Materials and Methods
BIO4AMB is a prospective, non-randomized mulitcentre, non-inferiority trial conducted in 35 centres in Europe and Australia comparing the use of 4F- and 6F-compatible devices. The main exclusion criteria included an American Society of Anaesthesiologists class ≥ 4, coagulation disorders, or social isolation. The primary endpoint was access-site complications within 30 days.
Results
The 4F group enrolled 390 patients and the 6F group 404 patients. Baseline characteristics were similar between the groups. Vascular closure devices were used in 7.7% (4F group) and 87.6% (6F group) of patients. Patients with vascular closure device use in the 4F group were subsequently excluded from the primary analysis, resulting in 361 patients in the 4F group. Time to haemostasis was longer for the 4F group, but the total procedure time was shorter (13.2 ± 18.8 vs. 6.4 ± 8.9 min, p < 0.0001, and 39.1 ± 25.2 vs. 46.4 ± 27.6 min,
p
< 0.0001). Discharge on the day of the procedure was possible in 95.0% (4F group) and 94.6% (6F group) of patients. Access-site complications were similar between the groups (2.8% and 3.2%) and included predominantly groin haematomas and pseudoaneurysms. Major adverse events through 30 days occurred in 1.7% and 2.0%, respectively.
Conclusions
Ambulatory peripheral vascular interventions are feasible and safe. The use of 4F devices resulted in similar outcomes compared to that of 6F devices.
Congenital disorders of glycosylation (CDG) are a rapidly expanding group of rare genetic defects in glycosylation. In a novel CDG subgroup of vacuolar‐ATPase (V‐ATPase) assembly defects, various ...degrees of hepatic injury have been described, including end‐stage liver disease. However, the CDG diagnostic workflow can be complex as liver disease per se may be associated with abnormal glycosylation. Therefore, we collected serum samples of patients with a wide range of liver pathology to study the performance and yield of two CDG screening methods. Our aim was to identify glycosylation patterns that could help to differentiate between primary and secondary glycosylation defects in liver disease. To this end, we analyzed serum samples of 1042 adult liver disease patients. This cohort consisted of 567 liver transplant candidates and 475 chronic liver disease patients. Our workflow consisted of screening for abnormal glycosylation by transferrin isoelectric focusing (tIEF), followed by in‐depth analysis of the abnormal samples with quadruple time‐of‐flight mass spectrometry (QTOF‐MS). Screening with tIEF resulted in identification of 247 (26%) abnormal samples. QTOF‐MS analysis of 110 of those did not reveal glycosylation abnormalities comparable with those seen in V‐ATPase assembly factor defects. However, two patients presented with isolated sialylation deficiency. Fucosylation was significantly increased in liver transplant candidates compared to healthy controls and patients with chronic liver disease. In conclusion, a significant percentage of patients with liver disease presented with abnormal CDG screening results. However, the glycosylation pattern was not indicative for a V‐ATPase assembly factor defect. Advanced glycoanalytical techniques assist in the dissection of secondary and primary glycosylation defects.
Background
Although oxygen is generally administered in a liberal manner in the perioperative setting, the effects of oxygen administration on dynamic cardiovascular parameters, filling status and ...cerebral perfusion have not been fully unraveled. Our aim was to study the acute hemodynamic and microcirculatory changes before, during and after arterial hyperoxia in mechanically ventilated patients after coronary artery bypass grafting (CABG) surgery.
Methods
This was a single-center physiological study in a tertiary care ICU in the Netherlands. Twenty-two patients scheduled for ICU admission after elective CABG were enrolled in the study between September 2014 and September 2015.
In the ICU, patients were exposed to a fraction of inspired oxygen (FiO
2
) of 90% allowing a 15-min wash-in period. Various hemodynamic parameters were measured using direct pressure signals and continuous arterial waveform analysis at three sequential time points: before, during and after hyperoxia.
Results
During a 15-min exposure to a fraction of inspired oxygen (FiO
2
) of 90%, the partial pressure of arterial oxygen (PaO
2
) and arterial oxygen saturation (SaO
2
) were significantly higher. The systemic resistance increased (
P
< 0.0001), without altering the heart rate. Stroke volume variation and pulse pressure variation decreased slightly. The cardiac output did not significantly decrease (
P
= 0.08). Mean systemic filling pressure and arterial critical closing pressure increased (
P
< 0.01), whereas the percentage of perfused microcirculatory vessels decreased (
P
< 0.01). Other microcirculatory parameters and cerebral blood flow velocity showed only slight changes.
Conclusions
We found that short-term hyperoxia affects hemodynamics in ICU patients after CABG. This was translated in several changes in central circulatory variables, but had only slight effects on cardiac output, cerebral blood flow and the microcirculation.
Clinical trial registration
Netherlands Trial Register: NTR5064
The physiology of the venous part of the human circulation seems to be a forgotten component of the circulation in critical care medicine. One of the main reasons, probably, is that measures of right ...atrial pressure (Pra) do not seem to be directly linked to blood flow. This perception is primarily due to an inability to measure the pressure gradient for venous return. The upstream pressure for venous return is mean systemic filling pressure (Pmsf) and it does not lend itself easily to be measured. Recent clinical studies now demonstrate the basic principles underpinning the measure of Pmsf at the bedside.
Using routinely available minimally invasive monitoring of continuous cardiac output and Pra, one can accurately construct venous return curves by performing a series of end-inspiratory hold maneuvers, in ventilator-dependent patients. From these venous return curves, the clinician can now finally obtain at the bedside not only Pmsf but also the derived parameters: resistance to venous return, systemic compliance and stressed volume.
Measurement of Pmsf is essential to describe the control of vascular capacitance. It is the key to distinguish between passive and active mechanisms of blood volume redistribution and partitioning total blood volume in stressed and unstressed volume.
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