l-Arginine Pathway Metabolites Predict Need for Intra-operative Shunt During Carotid Endarterectomy

OBJECTIVE/BACKGROUND

Asymmetric dimethylarginine (ADMA) inhibits nitric oxide (NO) synthesis and is a marker of atherosclerosis. This study examined the correlation between pre-operative l-arginine and ADMA concentration during carotid endarterectomy (CEA), and jugular lactate indicating anaerobic cerebral metabolism, jugular S100B reflecting blood-brain barrier integrity, and with factors of surgical intervention.

METHODS

The concentration of l-arginine, ADMA, and symmetric dimethylarginine was measured in blood taken under regional anaesthesia from the radial artery of 55 patients prior to CEA. Blood gas parameters, concentration of lactate, and S100B were also serially measured in blood taken from both the radial artery and the jugular bulb before and after carotid clamping, and after release of the clamp. To estimate anaerobic metabolism, the jugulo-arterial ratio of CO₂ gap/oxygen extraction was calculated.

RESULTS

Positive correlation was found between pre-operative ADMA levels and the ratio of jugulo-arterial CO₂ gap/oxygen extraction during clamp and reperfusion (p = .005 and p = .01, respectively). An inverse correlation was found between the pre-operative l-arginine concentration and jugular lactate at each time point (both p = .002). The critical pre-operative level of l-arginine was determined by receiver operator curve analysis. If l-arginine was below the cutoff value of 35 μmol/L, jugular S100B concentration was higher 24 h post-operatively (p = .03), and jugular lactate levels were increased during reperfusion (p = .02). The median pre-operative concentration of l-arginine was lower in patients requiring an intra-operative shunt than in patients without need of shunt (median: 30.3 μmol/L [interquartile range 24.4-34.4 μmol/L] vs. 57.6 μmol/L [interquartile range 42.3-74.5 μmol/L]; p = .002).

CONCLUSION

High pre-operative ADMA concentration predicts poor cerebral perfusion indicated by elevated jugulo-arterial CO₂ gap/oxygen extraction. Low pre-operative l-arginine concentration predicts the need for a shunt. The inverse correlation between pre-operative l-arginine concentration and both jugular lactate and S100B during carotid clamping suggests a protective role of the NO donor l-arginine.

Minimally Invasive Fixation versus Conservative Treatment of Undisplaced Scaphoid Fractures: A Cost-Effectiveness Study

This study compares the direct and indirect costs of conservative and minimally invasive treatment for undisplaced scaphoid fractures. Costs data concerning groups of non-operated and operated patients were analysed. Direct costs were higher in operated patients. Although highly variable, indirect costs were significantly smaller in operated patients and the total costs were higher in nonoperated patients. In conclusion, operative treatment of scaphoid fractures is initially more expensive than conservative treatment but markedly decreases the work compensation costs.

Decreased peroxisome proliferator-activated receptor γ level and signalling in sebaceous glands of patients with acne vulgaris

Little is known about the altered lipid metabolism-related transcriptional events occuring in sebaceous glands of patients with acne vulgaris. Peroxisome proliferator-activated receptor (PPAR)γ, a lipid-activated transcription factor, is implicated in differentiation and lipid metabolism of sebocytes. We have observed that PPARγ and its target genes, ADRP (adipose differentiation related protein) and PGAR (PPARγ angioprotein related protein) are expressed at lower levels in sebocytes from patients with acne than in those from healthy controls (HCs) Furthermore, endogenous PPARγ activator lipids such as arachidonic acid-derived keto-metabolites (e.g. 5KETE, 12KETE) are increased in acne-involved and nonacne-involved skin of patients with acne, compared with skin from healthy individuals. Our findings highlight the possible anti-inflammatory role of endogenous ligand-activated PPARγ signaling in human sebocyte biology, and suggest that modulating PPARγ- expression and thereby signaling might be a promising strategy for the clinical management of acne vulgaris.

The novel cardiac myosin activator omecamtiv mecarbil increases the calcium sensitivity of force production in isolated cardiomyocytes and skeletal muscle fibres of the rat

BACKGROUND AND PURPOSE

Omecamtiv mecarbil (OM) is a novel cardiac myosin activator drug for inotropic support in systolic heart failure. Here we have assessed the concentration-dependent mechanical effects of OM in permeabilized cardiomyocyte-sized preparations and single skeletal muscle fibres of Wistar-Kyoto rats under isometric conditions.

EXPERIMENTAL APPROACHES

Ca²⁺ -dependent active force production (F_active ), its Ca²⁺ sensitivity (pCa₅₀ ), the kinetic characteristics of Ca²⁺ -regulated activation and relaxation, and Ca²⁺ -independent passive force (F_passive ) were monitored in Triton X-100-skinned preparations with and without OM (3nM-10 μM).

KEY RESULTS

In permeabilized cardiomyocytes, OM increased the Ca²⁺ sensitivity of force production (ΔpCa₅₀ : 0.11 or 0.34 at 0.1 or 1 μM respectively). The concentration-response relationship of the Ca²⁺ sensitization was bell-shaped, with maximal effects at 0.3-1 μM OM (EC₅₀ : 0.08 ± 0.01 μM). The kinetics of force development and relaxation slowed progressively with increasing OM concentration. Moreover, OM increased F_passive in the cardiomyocytes with an apparent EC₅₀ value of 0.26 ± 0.11 μM. OM-evoked effects in the diaphragm muscle fibres with intrinsically slow kinetics were largely similar to those in cardiomyocytes, while they were less apparent in muscle fibres with fast kinetics.

CONCLUSIONS AND IMPLICATIONS

OM acted as a Ca²⁺ -sensitizing agent with a downstream mechanism of action in both cardiomyocytes and diaphragm muscle fibres. The mechanism of action of OM is connected to slowed activation-relaxation kinetics and at higher OM concentrations increased F_passive production.

The Stability and Structure of Complex Species Formed in Equilibrium Reactions of Diethyltin(IV) with N-D-Gluconylamino Acids in Aqueous Solution

Complex formation equilibria of diethyltin(IV) with five N-D-gluconylamino acids in aqueous solution (I = 0.1 M, NaClO4) were studied and the stabilities of the species were determined by potentiometric titrations. Diethyltin(IV) complexes of α-amino acid derivatives are water-soluble in the physiological pH range, while in the presence of N-D-gluconyl-β-alanine a precipitate is formed, which dissolves with increasing pH. 13C NMR measurements showed that in the N-D-gluconyl-α-amino acid complexes the ligand is coordinated through its deprotonated carboxylate oxygen, amide nitrogen and C(2)-hydroxy group, while for the soluble N-D-gluconyl-β-alanine complex the ligand is coordinated via the deprotonated carboxylate and C(3)-, C(4)-, C(5)-hydroxy groups. Mössbauer measurements reflected the geometry of the complexes formed.

Spontaneous histologic lesions of the adult naked mole rat (Heterocephalus glaber): a retrospective survey of lesions in a zoo population

Naked mole rats (NMRs; Heterocephalus glaber) are highly adapted, subterranean, eusocial rodents from semiarid regions of the eastern horn of Africa and the longest-living rodent known with a maximum life span of up to 30 years. They are a unique model for aging research due to their physiology, extreme longevity, and, when compared to mice and rats, resistance to cancer. Published surveys of disease in NMRs are sparse. Captive colonies in zoological collections provide an opportunity to monitor spontaneous disease over time in a seminatural environment. This retrospective study describes common lesions of a zoo population over a 15-year period during which 138 adult NMRs were submitted for gross and histologic evaluation. Of these, 61 (44.2%) were male, 77 (55.8%) female, 45 (32.6%) died, and 93 (67.4%) were euthanized. The most frequent cause of death or reason for euthanasia was conspecific trauma (bite wounds) and secondary complications. Some common histologic lesions and their prevalence were renal tubular mineralization (82.6%), hepatic hemosiderosis (64.5%), bite wounds (63.8%), chronic progressive nephropathy (52.9%), and calcinosis cutis (10.1%). In sum, 104 (75.4%) NMRs had more than one of the most prevalent histologic lesions. No malignant neoplasms were noted; however, there was a case of renal tubular adenomatous hyperplasia with nuclear atypia and compression that in rats is considered a preneoplastic lesion. This retrospective study confirms the NMR's relative resistance to cancer in spite of development of other degenerative diseases and highlights the utility of zoological databases for baseline pathological data on nontraditional animal models.

Recurring weather extremes alter the flowering phenology of two common temperate shrubs

The aim of this study is to explore the effects of heavy rain and drought on the flowering phenology of two shrub species Genista tinctoria and Calluna vulgaris. We conducted a field experiment over five consecutive years in Central Europe, applying annually recurring extreme drought and heavy rain events on constructed shrubland communities and recorded the flowering status. Further, we correlated spring temperature and precipitation with the onset of flowering. Both species showed a response to extreme weather events: drought delayed the mid flowering date of Genista tinctoria in 3 of 5 years by about 1 month and in 1 year advanced the mid flowering date by 10 days, but did not affect the length of flowering. Mid flowering date of Calluna vulgaris was not affected by drought, but the length of flowering was extended in 2 years by 6 and 10 days. For C. vulgaris the closer the drought occurred to the time of flowering, the larger the impact on the flowering length. Heavy rainfall advanced mid flowering date and reduced the length of flowering of Genista tinctoria by about 2 months in 1 year. Mid flowering date of Calluna vulgaris was not affected by heavy rain, but the length of flowering was reduced in 1 year by 4 days. Our data suggest that extreme weather events, including alterations to the precipitation regime, induce phenological shifts of plant species of a substantial magnitude. Thus, the impacts of climate extremes on plant life cycles may be as influential as gradual warming. Particularly, the variability in the timing of precipitation events appears to have a greater influence on flowering dynamics than the magnitude of the precipitation.

Corrective osteotomy of distal radial deformities: a new method of guided locking fixed screw positioning

Corrective osteotomy for distal radial malunion is a valuable but at times technically challenging operation. We have developed a new device to aid in the performance of the operation. We compared clinical use of the new technique with the standard technique. In 11 patients treated with the new technique the volar locking plate needed repositioning only once. With the standard technique in 17 patients the plate was repositioned in nine cases and needed bending in six cases. The new method corrected radial inclination (SD of 3° vs. 9°) and ulnar variance (SD of 0.9 mm vs. 1.4 mm) more predictably than the standard technique but there was no advantage in correction of volar tilt (SD of 6° vs. 4°). In our experience the new device makes corrective osteotomy of the distal radius easier and more reliable.