Targeted Endodontic Microsurgery: Implications of the Greater Palatine Artery

IntroductionTargeted Endodontic Microsurgery (TEMS) combines trephine burs and 3D-printed guides to make flapless maxillary palatal root-end surgery possible. This study assessed the location of the greater palatine artery (GPA), the relationship of the GPA to maxillary molar root ends, and the feasibility of flapless palatal-approach TEMS.MethodsThree endodontists analyzed 250 cone-beam computed tomographic images of maxillary molars for (1) transition morphology between the hard palate and the alveolar process adjacent to first and second molars as an indication of the most likely location of the GPA, (2) the superior-inferior relationship between the GPA and root ends, and (3) the feasibility of palatal-approach TEMS.ResultsPalatal transition morphology included 20% Spine, 72% Bridge, and 8% Smooth. GPA position as related to palatal root ends was classified as 34% superior, 40% adjacent, and 21% inferior. Five percent of classifications were undefined. TEMS was deemed feasible for 47% of maxillary first molars and 52% of second molars, and was significantly more feasible with GPAs superior to palatal root ends. Reasons for infeasibility included GPA proximity and unfavorable resection angle or level. Maxillary first molar palatal roots were 11.13 ± 2.68 mm from the greater palatine foramen (GPF) and 2.37 ± 1.46 mm from the GPA. Second molar palatal roots were 4.94 ± 2.55 mm from the GPF and 2.53 ± 1.77 mm from the GPA.ConclusionsPalatal transition morphology and GPA position adjacent to maxillary molars, as manifested in cone-beam computed tomographic coronal views, suggested maxillary palatal root TEMS could be accomplished with a 2-mm safety margin in 47% of first molars and 52% of second molars. Historical paradigms that do not consider flapless palatal surgical approaches may need to be revised.     

Pulmonary morphology in a multihospital collaborative extracorporeal membrane oxygenation project. I. Light microscopy.

This report presents the light microscopic morphology found at autopsy in 59 patients who participated in an organized controlled trial of extracorporeal oxygenation as therapy for acute respiratory failure. Observations were recorded as objectively as possible and were analyzed by computer. The experimental therapy produced no specific alteration in the observed pulmonary lesions. Many of the lesions tabulated had significant correlation coefficients with time, all of which were higher when correlated with the duration of respiratory failure than with the duration of the entire acute illness. The rapid progression of the lesions to fibrosis is emphasized as is the predilection of both early and late lesions to involve alveolar ducts to a far greater degree than the distal alveolar spaces. A unifying mechanistic hypothesis consistent with these observations, as well as others, is that the lesions may result as much from oxygen damage as from the original acute illness.     

The role of psychological and social factors in the relationship between attachment and suicide: A systematic review

Insecure attachment is widely accepted to be a risk factor for suicidal thoughts and behaviour. To increase our understanding of this distal association, the current systematic review aimed to evaluate empirical evidence that has investigated the role of psychosocial mechanisms within this relationship. Sixteen original research articles were identified, with the majority carrying out mediational analyses to test their hypotheses. Substantial heterogeneity was found across studies with regards to their theoretical approach to assessing attachment, suicide‐related outcomes, sample population, statistical analyses, and the psychological factors under investigation. Nevertheless, this emergent evidence base indicates that a range of predisposing, precipitating, and crisis‐state factors may mediate the association between attachment security and suicidality. Studies that investigated moderating factors did not report significant findings, and the mediating role for psychiatric diagnoses remains unclear. Furthermore, this emerging research base is limited by an over‐reliance on cross‐sectional designs and self‐reported data. Longitudinal and experimental designs are required to verify causal pathways and to investigate whether trait vulnerabilities interact with acute stressors to increase suicide risk. Finally, disorganized attachment has been overlooked so far and should be given greater consideration going forward.     

Fast noninvasive activation and inhibition of neural and network activity by vertebrate rhodopsin and green algae channelrhodopsin

Techniques for fast noninvasive control of neuronal excitability will be of major importance for analyzing and understanding neuronal networks and animal behavior. To develop these tools we demonstrated that two light-activated signaling proteins, vertebrate rat rhodopsin 4 (RO4) and the green algae channelrhodospin 2 (ChR2), could be used to control neuronal excitability and modulate synaptic transmission. Vertebrate rhodopsin couples to the Gi/o, pertussis toxin-sensitive pathway to allow modulation of G protein-gated inward rectifying potassium channels and voltage-gated Ca2+ channels. Light-mediated activation of RO4 in cultured hippocampal neurons reduces neuronal firing within ms by hyperpolarization of the somato-dendritic membrane and when activated at presynaptic sites modulates synaptic transmission and paired-pulse facilitation. In contrast, somato-dendritic activation of ChR2 depolarizes neurons sufficiently to induce immediate action potentials, which precisely follow the ChR2 activation up to light stimulation frequencies of 20 Hz. To demonstrate that these constructs are useful for regulating network behavior in intact organisms, embryonic chick spinal cords were electroporated with either construct, allowing the frequency of episodes of spontaneous bursting activity, known to be important for motor circuit formation, to be precisely controlled. Thus light-activated vertebrate RO4 and green algae ChR2 allow the antagonistic control of neuronal function within ms to s in a precise, reversible, and noninvasive manner in cultured neurons and intact vertebrate spinal cords.     

Chronic lymphocytic leukaemia cells drive the global CD4+ T cell repertoire towards a regulatory phenotype and leads to the accumulation of CD4+ forkhead box P3+ T cells

Advanced chronic lymphocytic leukaemia (CLL) is associated with profound immunodeficiency, including changes in T regulatory cells (T(regs)). We determined the pattern of expression of forkhead box P3 (FoxP3), CD25, CD27 and CD127 and showed that the frequency of CD4+ FoxP3+ T cells was increased in CLL patients (12% versus 8% in controls). This increase was seen only in advanced disease, with selective expansion of FoxP3-expressing cells in the CD4+ CD25(low) population, whereas the number of CD4+ CD25(high) FoxP3+ cells was unchanged. CD4+ CD25(low) cells showed reduced expression of CD127 and increased CD27, and this regulatory phenotype was also seen on all CD4 T cells subsets in CLL patients, irrespective of CD25 or FoxP3 expression. Incubation of CD4+ T cells with primary CLL tumours led to a sixfold increase in the expression of FoxP3 in CD4+ CD25- T cells. Patients undergoing treatment with fludarabine demonstrated a transient increase in the percentage of CD4+ FoxP3+ T cells, but this reduced to normal levels post-treatment. This work demonstrates that patients with CLL exhibit a systemic T cell dysregulation leading to the accumulation of CD4+ FoxP3+ T cells. This appears to be driven by interaction with malignant cells, and increased understanding of the mechanisms that are involved could provide novel avenues for treatment.     

Cholesterol-induced upregulation of angiotensin II and its effects on monocyte-endothelial interaction and superoxide production.

Atherogenesis involves an early endothelial dysfunction hallmarked by elevated free radical production and increased adhesiveness for monocytes. It was hypothesized that activation of the tissue renin angiotensin system may contribute to the endothelial alteration. To test this hypothesis, thoracic aortae were isolated from normocholesterolemic (NC; n = 6) and hypercholesterolemic (HC; n = 6; diet: 0.5% cholesterol; 6 weeks) New Zealand white rabbits, and incubated for 2 h with the angiotensin II (Ang II) receptor antagonist Sar-1,Ile-8-Ang II, the antioxidant pyrolidine dithiocarbamate (PDTC) and the protein kinase C (PKC) antagonist staurosporin. Superoxide production from aortic segments was measured by lucigenin-enhanced chemiluminescence. In comparison to the normocholesterolemic state, hypercholesterolemia led to a significant increase in superoxide production (221 +/- 44%, p < 0.02); this was reduced by ex vivo treatment of the vessel segment with Ang II-antagonist (to 130 +/- 29%; p < 0.04 vs HC), or PKC-antagonist (to 86 +/- 26%; p < 0.001 vs HC), or PDTC (to 103 +/- 27%; p < 0.02 vs HC). Monocyte-endothelial interaction was assessed by functional binding assay. When compared to normocholesterolemic rabbits, hypercholesterolemia led to a twofold increase in monocyte binding (74 +/- 13 vs 37 +/- 4 monocytoid cells per high power field (m/hpf); p < 0.03). The Ang II-antagonist and the PKC-antagonist led to a normalization of monocyte-endothelial binding (Ang II-antagonist: 37 +/- 9 m/hpf; PKC-antagonist: 41 +/- 17 m/hpf; p < 0.05). In conclusion, these results indicate that hypercholesterolemia activates the tissue renin angiotensin system, which results in an increased endothelial production of superoxide and monocyte adhesiveness. Ang II-antagonist inhibits free radical production and monocyte adhesion through a mechanism which may include PKC.     

Usefulness of vernakalant hydrochloride injection for rapid conversion of atrial fibrillation

The objective of the present study was to assess the safety and effectiveness of vernakalant hydrochloride injection (RSD1235), a novel antiarrhythmic drug, for the conversion of atrial fibrillation (AF) or atrial flutter to sinus rhythm (SR). Patients with either AF or atrial flutter were randomized in a 1:1 ratio to receive vernakalant (n = 138) or placebo (n = 138) and were stratified by an arrhythmia duration of >3 hours to ≤7 days (short duration) and 8 to ≤45 days (long duration). The first infusion of placebo or vernakalant (3 mg/kg) was given for 10 minutes followed by a second infusion of placebo or vernakalant (2 mg/kg) 15 minutes later if the arrhythmia had not terminated. A total of 265 patients were randomized and received treatment. The primary end point was conversion of AF to SR for ≥1 minute within 90 minutes of the start of the drug infusion in the short-duration AF group. Of the 86 patients receiving vernakalant in the short-duration AF group, 44 (51.2%) demonstrated conversion to SR compared to 3 (3.6%) of the 84 in the placebo group (p <0.0001). The median interval to conversion of short-duration AF to SR in the responders given vernakalant was 8 minutes. Of the entire AF population (short- and long-duration AF), 47 (39.8%) of the 118 vernakalant patients experienced conversion of AF to SR compared to 4 (3.3%) of the 121 placebo patients (p <0.0001). Transient dysgeusia and sneezing were the most common adverse events in the vernakalant patients. One vernakalant patient who had severe aortic stenosis experienced hypotension and ventricular fibrillation and died. In conclusion, vernakalant demonstrated a rapid and high rate of conversion for short-duration AF and was well tolerated.