Potassium deficiency reduces grapevine transpiration through decreased leaf area and stomatal conductance

Plants require potassium (K) to support growth and regulate hydraulics. Yet, K's effects on transpiration are still speculated. We hypothesized that K deficiency would limit grapevine water uptake by limiting canopy size and stomatal conductance (gs). Hence, we constructed large (2 m3) lysimeters and recorded vine transpiration for three years (2020-2022) under three fertilization application rates (8, 20, or 58 mg K L-1 in irrigation). Maximal K availability supported transpiration up to 75 L day-1, whereas K-deficient vines transpired only 60 L day-1 in midsummer. Limited vine growth and canopy size mainly accounted for reduced transpiration under low K conditions. Hence, considering K demand in addition to supply, we compared K deficiency effects on vines bearing 20 or 50 fruit clusters and found that reduced gs further limited transpiration when yields were high. Although fruits were strong K sinks, high yields did not alter K uptake because lower vegetative growth countered the additional K demands. Potassium deficiency leads to lower transpiration and productivity. Yet, internal mineral allocation compensates for fruit K uptake and masks biochemical indices or physiological proxies for K deficiency. Thus, decision support tools should integrate mineral availability, seasonal growth, and yield projections to determine grapevine water demands.

Optimization of Radiofrequency Needle Placement in Percutaneous Cordotomy Using Electromyography in the Deeply Sedated Patient

BACKGROUND AND OBJECTIVES

Cordotomy, the selective disconnection of the nociceptive fibers in the spinothalamic tract, is used to provide pain palliation to oncological patients suffering from intractable cancer-related pain. Cordotomies are commonly performed using a cervical (C1-2) percutaneous approach under imaging guidance and require patients' cooperation to functionally localize the spinothalamic tract. This can be challenging in patients suffering from extreme pain. It has recently been demonstrated that intraoperative neurophysiology monitoring by electromyography may aid in safe lesion positioning. The aim of this study was to evaluate the role of compound muscle action potential (CMAP) in deeply sedated patients undergoing percutaneous cervical cordotomy (PCC).

METHODS

A retrospective analysis was conducted of all patients who underwent percutaneous cordotomy while deeply sedated between January 2019 and November 2022 in 2 academic centers. The operative report, neuromonitoring logs, and clinical medical records were evaluated.

RESULTS

Eleven patients underwent PCC under deep sedation. In all patients, the final motor assessment prior to ablation was done using the electrophysiological criterion alone. The median threshold for evoking CMAP activity at the lesion site was 0.9 V ranging between 0.5 and 1.5 V (average 1 V ± 0.34 V SD). An immediate, substantial decrease in pain was observed in 9 patients. The median pain scores (Numeric Rating Scale) decreased from 10 preoperatively (range 8-10) to a median 0 (range 0-10) immediately after surgery. None of our patients developed motor deficits.

CONCLUSION

CMAP-guided PCC may be feasible in deeply sedated patients without added risk to postoperative motor function. This technique should be considered in a group of patients who are not able to undergo awake PCC.

Elevated CO2 concentration increases maize growth under water deficit or soil salinity but with a higher risk of hydraulic failure

Climate change presents a challenge for plants to acclimate their water relations under changing environmental conditions, and may increase the risks of hydraulic failure under stress. In this study, maize plants were acclimated to two different CO2 concentrations ([CO2]; 400 ppm and 700 ppm) while under either water stress (WS) or soil salinity (SS) treatments, and their growth and hydraulic traits were examined in detail. Both WS and SS inhibited growth and had significant impacts on hydraulic traits. In particular, the water potential at 50% loss of stem hydraulic conductance (P50) decreased by 1 MPa in both treatments at 400 ppm. When subjected to elevated [CO2], the plants under both WS and SS showed improved growth by 7-23%. Elevated [CO2] also significantly increased xylem vulnerability (measured as loss of conductivity with decreasing xylem pressure), resulting in smaller hydraulic safety margins. According to the plant desiccation model, the critical desiccation degree (time×vapor pressure deficit) that the plants could tolerate under drought was reduced by 43-64% under elevated [CO2]. In addition, sensitivity analysis showed that P50 was the most important trait in determining the critical desiccation degree. Thus, our results demonstrated that whilst elevated [CO2] benefited plant growth under WS or SS, it also interfered with hydraulic acclimation, thereby potentially placing the plants at a higher risk of hydraulic failure and increased mortality.

Rapid leaf xylem acclimation diminishes the chances of embolism in grapevines

Under most conditions tight stomatal regulation in grapevines (Vitis vinifera) avoids xylem embolism. The current study evaluated grapevine responses to challenging scenarios that might lead to leaf embolism and consequential leaf damage. We hypothesized that embolism would occur if the vines experienced low xylem water potential (Ψx) shortly after bud break or later in the season under a combination of extreme drought and heat. We subjected vines to two potentially dangerous environments: (i) withholding irrigation from a vineyard grown in a heatwave-prone environment, and (ii) subjecting potted vines to terminal drought 1 month after bud break. In the field experiment, a heatwave at the beginning of August resulted in leaf temperatures over 45 °C. However, effective stomatal response maintained the xylem water potential (Ψx) well above the embolism threshold, and no leaf desiccation was observed. In the pot experiment, leaves of well-watered vines in May were relatively vulnerable to embolism with 50% embolism (P50) at -1.8 MPa. However, when exposed to drought, these leaves acclimated their leaf P50 by 0.65 MPa in less than a week and before reaching embolism values. When dried to embolizing Ψx, the leaf damage proportion matched (percentage-wise) the leaf embolism level. Our findings indicate that embolism and leaf damage are usually avoided by the grapevines' efficient stomatal regulation and rapid acclimation of their xylem vulnerability.

Medical cannabis for refractory cancer-related pain in a specialised clinical service: a cross-sectional study

BACKGROUND AND OBJECTIVES

Cancer-related pain management in advanced stages presents a significant challenge that often requires a multidisciplinary approach. Although advancements in pharmacological and interventional therapies, a considerable number of patients still suffer from refractory pain, leading to unmet clinical needs. This study shares our experience with medical cannabis (MC) as a potential therapy for this specific population of patients with cancer-related refractory pain.

METHODS

In a cross-sectional study, 252 consecutive refractory cancer-related pain patients (mean age=61.71, SD=14.02, 47.6% males) filled out detailed self-report questionnaires. Of these, 126 patients (55%) were treated with MC and 105 patients (45%) were not.

RESULTS

Most patients received pain management from their oncologist, not a pain specialist. MC was mainly started for pain relief, sleep difficulties and anorexia. About 70% of patients reported subjective improvement from MC, with almost 40% reporting a significant improvement in coping with their illness. Side effects were generally mild, with fatigue and dizziness being the most common (21.78% and 23.46%, respectively). No patient required dedicated medical care for side effects. Of non-users, 65% had tried MC before and stopped due to lack of effectiveness or side effects (39.7% and 34.6%, respectively).

CONCLUSION

Refractory cancer pain necessitates innovative approaches. This registry highlights that MC can effectively improve symptoms in non-responsive patients, with favourable safety profiles for this vulnerable population.

Relationships between xylem embolism and tree functioning during drought, recovery, and recurring drought in Aleppo pine

Recent findings suggest that trees can survive high levels of drought-induced xylem embolism. In many cases, the embolism is irreversible and, therefore, can potentially affect post-drought recovery and tree function under recurring droughts. We examined the development of embolism in potted Aleppo pines, a common species in hot, dry Mediterranean habitats. We asked (1) how post-drought recovery is affected by different levels of embolism and (2) what consequences this drought-induced damage has under a recurring drought scenario. Young trees were dehydrated to target water potential (Ψx ) values of -3.5, -5.2 and -9.5 MPa (which corresponded to ~6%, ~41% and ~76% embolism), and recovery of the surviving trees was measured over an 8-months period (i.e., embolism, leaf gas-exchange, Ψx ). An additional group of trees was exposed to Ψx of -6.0 MPa, either with or without preceding drought (Ψx of -5.2 MPa) to test the effect of hydraulic damage during repeated drought. Trees that reached -9.5 MPa died, but none from the other groups. Embolism levels in dying trees were on average 76% of conductive xylem and no tree was dying below 62% embolism. Stomatal recovery was negatively proportional to the level of hydraulic damage sustained during drought, for at least a month after drought relief. Trees that experienced drought for the second time took longer to reach fatal Ψx levels than first-time dehydrating trees. Decreased stomatal conductance following drought can be seen as "drought legacy," impeding recovery of tree functioning, but also as a safety mechanism during a consecutive drought.

Xylem resistance to cavitation increases during summer in Pinus halepensis

Cavitation resistance has often been viewed as a relatively static trait, especially for stems of forest trees. Meanwhile, other hydraulic traits, such as turgor loss point (Ψ_tlp ) and xylem anatomy, change during the season. In this study, we hypothesized that cavitation resistance is also dynamic, changing in coordination with Ψ_tlp . We began with a comparison of optical vulnerability (OV), microcomputed tomography (µCT) and cavitron methods. All three methods significantly differed in the slope of the curve,Ψ₁₂ and Ψ₈₈ , but not in Ψ₅₀ (xylem pressures that cause 12%, 88%, 50% cavitation, respectively). Thus, we followed the seasonal dynamics (across 2 years) of Ψ₅₀ in Pinus halepensis under Mediterranean climate using the OV method. We found that Ψ₅₀ is a plastic trait with a reduction of approximately 1 MPa from the end of the wet season to the end of the dry season, in coordination with the dynamics of the midday xylem water potential (Ψ_midday ) and the Ψ_tlp . The observed plasticity enabled the trees to maintain a stable positive hydraulic safety margin and avoid cavitation during the long dry season. Seasonal plasticity is vital for understanding the actual risk of cavitation to plants and for modeling species' ability to tolerate harsh environments.

The effect of subcutaneous fat and skin-to-lamina distance on complications and functional outcomes of minimally invasive lumbar decompression

PURPOSE

Minimally invasive lumbar decompression (MIS) in obese pzatients is technically challenging due to the use of longer tube retractors. The purpose of this study was to evaluate the impact of the thickness of the soft tissue and subcutaneous fat on complications, revisions, and patient-reported functional outcomes after MIS.

METHODS

This is a retrospective analysis of 148 consecutive patients who underwent minimally invasive lumbar decompression at our institute between 2013 and 2017 and had at least one year of follow-up. Analysis was performed five times, each time the study group was defined by another measure of adiposity: BMI > 30, skin to lamina distance at the site of surgery and at L4 > 6 cm, and subcutaneous fat thickness at the site of surgery and at L4 > 3 cm. Outcomes included intraoperative complications (durotomy or neurological deficit), possibly inadequate decompression (residual disc, reoperation), length of stay, return to the emergency room or readmission, postoperative medical complications, and functional outcomes: visual analog scores for back and leg pain, and Oswestry Disability Index (ODI).

RESULTS

Patients with a thicker layer soft tissue had a significantly higher burden of comorbidities than controls, including higher prevalence of cardiovascular disease (p = 0.002), diabetes (p < 0.001), hypertension (p < 0.001) and higher ASA scores (p = 0.002). Nevertheless, there was no significant difference between the patient groups in surgical and medical complications, functional outcomes, and other assessed outcomes.

CONCLUSION

Our results indicate that minimally invasive lumbar decompression is safe and effective for patients with a thick layer of soft tissue and subcutaneous fat.

Early Interventional Treatments for Patients with Cancer Pain: A Narrative Review

Between 10% and 20% of patients with cancer-related pain cannot achieve adequate control following the three-step ladder guidelines by the World Health Organization. Therefore, a "fourth step", including interventional approaches, has been suggested for those cases. Systematic reviews support the early use of interventional procedures to treat refractory cancer pain, control symptoms and prevent opioid dose escalation. There is strong evidence of the efficacy of celiac plexus or splanchnic neurolysis, vertebroplasty, kyphoplasty and intrathecal drug delivery. Those procedures have been found to be associated with a decrease in the symptom burden and opioid consumption, improved quality of life, and suggested as having a potentially positive impact on survival. Several studies have recommended using specific interventional techniques at earlier stages, possibly even when opioid treatment is first being considered. Conversely, leaving these options as a last analgesic resource might not be advisable since the burden these procedures might impose on too ill patients is significant. The objective of this review was to collect the available evidence published on the use of interventional treatments for refractory cancer pain with a particular interest in comparing early versus late indications. The results of the search demonstrated a very low number and quality of articles particularly addressing this question. This scarce number of evidence precluded performing a systematic analysis. A detailed and narrative description of the potential benefits of integrating interventional techniques into clinical guidelines at the early stages of the disease is provided.

Does Tobacco Smoking Affect the Postoperative Outcome of MIS Lumbar Decompression Surgery?

BACKGROUND

Tobacco smoking is a major cause of morbidity and mortality worldwide. Several authors reported a significant negative impact of smoking on the outcome of spinal surgeries. However, comparative studies on the effect of smoking on the outcome of minimally invasive (MIS) spinal decompression are rare with conflicting results. In this study, we aimed to evaluate clinical outcomes and postoperative complications following MIS decompression in current and former smoking patients compared to those of non-smoking patients.

METHODS

We used our prospectively collected database to retrospectively analyse the records of 188 consecutive patients treated with MIS lumbar decompression at our institution between November 2013 and July 2017. Patients were divided into groups of smokers (S), previous smokers (PS) and non-smokers (N). The S group and the PS group comprised 31 and 40 patients, respectively. The N group included 117 patients. The outcome measures included perioperative complications, revision surgery and length of stay. Patient-reported outcome measures included a visual analogue scale (VAS) for back pain and leg pain, as well as the Oswestry disability index (ODI) for evaluating functional outcomes.

RESULTS

Demographic variables, comorbidity and other preoperative variables were comparable between the three groups. A comparison of perioperative complications and revision surgery rates showed no significant difference between the groups. All groups showed significant improvement in their ODI and VAS scores at 12 and 24 months following surgery. As shown by a multivariate analysis, current smokers had lower chances of improvement, exceeding the minimal clinical important difference (MCID) in ODI and VAS for leg pain at 12 months but not 24 months postoperatively.

CONCLUSIONS

Our findings show that except for a possible delay in improvement in leg pain and disability, tobacco smoking has no substantial adverse impact on complications and revision rates following MIS spinal decompressions.

Xylem conduit deformation across vascular plants: an evolutionary spandrel or protective valve?

The hydraulic system of vascular plants and its integrity is essential for plant survival. To transport water under tension, the walls of xylem conduits must approximate rigid pipes. Against this expectation, conduit deformation has been reported in the leaves of a few species and hypothesized to function as a 'circuit breaker' against embolism. Experimental evidence is lacking, and its generality is unknown. We demonstrated the role of conduit deformation in protecting the upstream xylem from embolism through experiments on three species and surveyed a diverse selection of vascular plants for conduit deformation in leaves. Conduit deformation in minor veins occurred before embolism during slow dehydration. When leaves were exposed to transient increases in transpiration, conduit deformation was accompanied by large water potential differences from leaf to stem and minimal embolism in the upstream xylem. In the three species tested, collapsible vein endings provided clear protection of upstream xylem from embolism during transient increases in transpiration. We found conduit deformation in diverse vascular plants, including 11 eudicots, ginkgo, a cycad, a fern, a bamboo, and a grass species, but not in two bamboo and a palm species, demonstrating that the potential for 'circuit breaker' functionality may be widespread across vascular plants.

Low Back Pain Patients' Perceptions Regarding Their Own Radiology Reports: Pre-Intervention Survey

Purpose

While advanced medical technology and unlimited access to medical information might benefit and empower patients, these same advantages may pose some risks, especially in the cases where patients have direct access to advanced imaging studies. The aim of this work was to evaluate three domains related to patients with lower back pain: the patients' perceptions, misconceptions and the experience of anxiety-related symptoms following direct access to their thoraco-lumbar spine radiology report. An additional aim was the assessment of possible associations with catastrophization.

Patients and Methods

Patients who were referred to the spine clinic, following the completion of a CT or MRI of their thoraco-lumbar spine were surveyed. Patient perceptions of the importance of having direct access to their imaging report and of the concern they attribute to the medical terms found in their report were evaluated using a set of questionnaires. The medical terms severity scores were then correlated to a reference clinical score created for the same medical terms by spine surgeons. Lastly, patients' anxiety-related symptoms and Pain Catastrophizing Scale (PCS) after reading their radiology report were evaluated.

Results

Data from 162 participants (44.6% female), with mean age of 53.1 ± 15.6 years, were collected. Sixty-three percent of the patients stated that reading their report helped them gain better understanding of their medical condition and 84% agreed that having early access to the report helped improve communication with the physician. Patients' degree of concern associated with the medical terms in their imaging report ranged between 2.07 and 3.75, on a scale of 1-5. The patient's degree of concerns were significantly higher for six common medical terms and significantly lower in one, when compared to experts' opinions. A mean (± SD) of 2.86±2.79 anxiety-related symptoms was reported. The mean Pain Catastrophizing Scale (PSC) score was 29.18 ±11.86, ranging from 2 to 52. Both the degree of concerns and the number of symptoms reported were significantly associated with the PCS.

Conclusion

Direct access to radiology reports might provoke anxiety symptoms, especially in patients with a tendency for catastrophic thinking. Increasing awareness amongst spine clinicians and radiologist about possible risks associated with direct access to radiology reports could contribute to preventing patients' misconceptions and unnecessary anxiety-related symptoms.

Facet overhang: A novel parameter in the pathophysiology of multifidus muscle atrophy

The relationship between degenerative zygapophysial joint (facet) arthropathy and multifidus muscle atrophy has not been rigorously evaluated. The purpose of this study was to determine if specific morphological features of degenerative facet arthropathy are correlated with multifidus muscle atrophy. We retrospectively reviewed medical records and imaging studies of patients with lumbar spinal stenosis. Facet overhang, bridging osteophyte formation, facet effusion, and facet angles were evaluated by univariable and multivariable regression to identify independent associations with deep and superficial parts of the multifidus total cross-sectional area (tCSA), functional cross-sectional area (fnCSA), and fatty infiltration (FI). Facet overhang was classified as severe in 50 females (53.2%) versus 56 males (36.9%) (p = 0.030). Severity of facet overhang and female sex were independently associated with smaller deep part of the multifidus tCSA and fnCSA as well as higher FI, reflecting greater atrophy of the deep region compared to total muscle mass. In comparison, severe facet overhang (p < 0.001; OR = 3.47, 95% CI = 2.13-5.66) and female sex (p < 0.001; OR = 4.19, 95% CI = 2.58-6.79) were independently associated only with higher superficial part of the multifidus FI, reflecting muscle steatosis without significant lean muscle atrophy. In patients with degenerative lumbar spinal stenosis, facet overhang is an independent risk factor for deep part of the multifidus atrophy. Bridging osteophyte formation, facet effusion, and facet angles were not independently associated with deep part of the multifidus atrophy.

Lesions to both somatic and affective pain pathways lead to decreased salience network connectivity

Human pain is a salient stimulus composed of two main components: a sensory\somatic component, carrying peripheral nociceptive sensation via the spino-thalamic tract and brainstem nuclei to the thalamus and then to sensory cortical regions, and an affective (suffering) component, where information from central thalamic nuclei is carried to the anterior insula, dorsal anterior cingulate cortex and other regions. While the sensory component processes information about stimulus location and intensity, the affective component processes information regarding pain-related expectations, motivation to reduce pain, and pain unpleasantness. Unlike investigations of acute pain that are based on the introduction of real-time stimulus during brain recordings, chronic pain investigations are usually based on longitudinal and case-control studies, which are limited in their ability to infer the functional network topology of chronic pain. In the current study, we utilized the unique opportunity to target the central nervous system’s pain pathways in two different hierarchical locations to establish causality between pain relief and specific connectivity changes seen within the salience and sensorimotor networks. We examined how lesions to the affective and somatic pain pathways affect resting-state network topology in cancer patients suffering from severe intractable pain. Two procedures have been employed: percutaneous cervical cordotomy (n = 15), hypothesized to disrupt the transmission of the sensory component of pain along the spino-thalamic tract, or stereotactic cingulotomy (n = 7), which refers to bilateral intra-cranial ablation of an area in the dorsal anterior cingulate cortex and is known to ameliorate the affective component of pain. Both procedures led to immediate significant alleviation of experienced pain and decreased functional connectivity within the salience network. However, only the sensory procedure (cordotomy) led to decreased connectivity within the sensorimotor network. Thus, our results support the existence of two converging systems relaying experienced pain, showing that pain-related suffering can be either directly influenced by interfering with the affective pathway, or indirectly influenced by interfering with the ascending spino-thalamic tract.

Minimally invasive discectomy versus open laminectomy and discectomy for the treatment of cauda equina syndrome: A preliminary study and case series

Background

Cauda Equina syndrome (CES) is a potentially devastating condition and is treated usually with urgent open surgical decompression of the spinal canal. Currently, the role of minimally invasive discectomy (MID) as an alternative surgical technique for CES is unclear.

Objective

The purpose of this study was to compare clinical outcomes following MID and open laminectomy and discectomy for the treatment of CES.

Methods

The study cohort included patients that underwent surgery due to CES at our institute. Patients' outcomes included: surgical complications, length of hospitalization, postoperative lower extremity motor score (LEMS), Numerical Rating Scale (NRS) for leg and back pain, Oswestry disability index (ODI), and the EQ-5D health-related quality of life questionnaire.

Results

Twelve patients underwent MID and 12 underwent open laminectomy and discectomy. Complications and revisions rates were comparable between the groups. Postoperative urine incontinence and saddle dysesthesia improved in 50% of patients in both groups. LEMS improved from 47.08 ± 5.4 to 49.27 ± 0.9 in the MID group and from 44.46 ± 5.9 to 49.0 ± 1.4 in the open group. Although, leg pain improved in both groups from 8.4 ± 2.4 to 3 ± 2.1 in the MID and from 8.44 ± 3.3 to 3.88 ± 3 in the open group, significant improvement in back pain was found only in the MID group. Final functional scores were similar between groups.

Conclusions

Our preliminary results suggest that minimally invasive discectomy is an effective and safe procedure for the treatment of CES when compared to open laminectomy and discectomy. However, MID in these cases should only be considered by surgeons experienced in minimally invasive spine surgery. Further studies with bigger sample sizes and long-term follow-ups are needed.

Sarcopenia Is an Independent Risk Factor for Subsequent Osteoporotic Vertebral Fractures Following Percutaneous Cement Augmentation in Elderly Patients

Introduction: Subsequent osteoporotic vertebral fractures (SOVF) are a serious complication of osteoporosis that can lead to spinal deformity, chronic pain and disability. Several risk factors have been previously identified for developing SOVF. However, there are conflicting reports regarding the association between sarcopenia and multiple vertebral compression fractures. As such, the goal of this study was to investigate whether sarcopenia is an independent risk factor of SOVF. Methods:This was a retrospective case–control study of elderly patients who underwent percutaneous vertebral augmentation (PVA) due to a new osteoporotic vertebral compression fracture (OVCF). Collected data included: age, sex, BMI, steroid treatment, fracture level and type, presence of kyphosis at the level of the fracture and bone mineral density (BMD). Identification of SVOFs was based on clinical notes and imaging corroborating the presence of a new fracture. Sarcopenia was measured using the normalized psoas muscle total cross-sectional area (nCSA) at the L4 level. Results: Eighty-nine patients that underwent PVA were followed for a minimum of 24 months. Average age was 80.2 ± 7.1 years; 58 were female (65.2%) and 31 male (34.8%). Psoas muscle nCSA was significantly associated with age (p = 0.031) but not with gender (p = 0.129), corticosteroid treatment (p = 0.349), local kyphosis (p = 0.715), or BMD (p = 0.724). Sarcopenia was significantly associated with SOVF (p = 0.039) after controlling for age and gender. Conclusions: Psoas muscle nCSA can be used as a standalone diagnostic tool of sarcopenia in patients undergoing PVA. In patients undergoing PVA for OVCF, sarcopenia is an independent risk factor for SOVF.

Seasonal adjustment of leaf embolism resistance and its importance for hydraulic safety in deciduous trees

Embolism resistance is often viewed as seasonally stable. Here we examined the seasonality in the leaf xylem vulnerability curve (VC) and turgor loss point (Ψ_TLP ) of nine deciduous species that originated from Mediterranean, temperate, tropical, or sub-tropical habitats and were growing on the Volcani campus, Israel. All four Mediterranean/temperate species exhibited a shift of their VC to lower xylem pressures (Ψ_x ) along the dry season, in addition to two of the five tropical/sub-tropical species. In three of the species that exhibited VC seasonality, it was critical for avoiding embolism in the leaf. In total, seven out of the nine species avoided embolism. The seasonal VC adjustment was over two times higher as compared with the seasonal adjustment of Ψ_TLP , resulting in improved hydraulic safety as the season progressed. The results suggest that seasonality in the leaf xylem vulnerability is common in species that originate from Mediterranean or temperate habitats that have large seasonal environmental changes. This seasonality is advantageous because it enables a gradual seasonal reduction in the Ψ_x without increasing the danger of embolism. The results also highlight that measuring the minimal Ψ_x and the VC at different times can lead to erroneous estimations of the hydraulic safety margins. Changing the current hydraulic dogma into a seasonal dynamic in the vulnerability of the xylem itself should enable physiologists to understand plants' responses to their environment better.

Is the Erector Spinae Plane Block Effective for More than Perioperative Pain? A Retrospective Analysis

Introduction: The thoracic Erector Spinae Plane Block (ESPB) is an ultrasound-guided block that has gained popularity and is widely used in acute pain setups. However, data regarding its role in chronic and cancer-related pain are anecdotal. Material and Methods: The study is a retrospective analysis of patients who underwent ESPB. The cohort was divided into subgroups based on three determinants: etiology, pain type, and chronicity. Results: One hundred and ten patients were included, and genders were affected equally. The average age was 61.2 ± 16.1 years. The whole group had a statistically significant reduction in a numerical rating scale (NRS) (7.4 ± 1.4 vs. 5.0 ± 2.6, p-value > 0.001). NRS reduction for 45 patients (41%) exceeded 50% of the pre-procedural NRS. The mean follow-up was 7.9 ± 4.6 weeks. Baseline and post-procedure NRS were comparable between all subgroups. The post-procedural NRS was significantly lower than the pre-procedural score within each group. The proportion of patients with over 50% improvement in NRS was lower for those with symptom duration above 12 months (p-value = 0.02). Conclusions: Thoracic ESPB is a simple and safe technique. The results support the possible role of ESPB for chronic as well as cancer-related pain.

In situ, direct observation of seasonal embolism dynamics in Aleppo pine trees growing on the dry edge of their distribution

Xylem embolism impairs hydraulic conductivity in trees and drives drought-induced mortality. While embolism has been monitored in vivo in potted plants, and research has revealed evidence of embolism in field-grown trees, continuous in situ monitoring of cavitation in forests is lacking. Seasonal patterns of embolism were monitored in branchlets of Aleppo pine (Pinus halepensis) trees growing in a dry Mediterranean forest. Optical visualization (OV) sensors were installed on terminal branches, in addition to monthly sampling for micro computed tomography scans. We detected 208 cavitation events among four trees, which represented an embolism increase from zero to c. 12% along the dry season. Virtually all the cavitation events occurred during daytime hours, with 77% occurring between 10:00 and 17:00 h. The probability for cavitation in a given hour increased as vapor pressure deficit (VPD) increased, up to a probability of 42% for cavitation when VPD > 5 kPa. The findings uniquely reveal the instantaneous environmental conditions that lead to cavitation. The increased likelihood of cavitation events under high VPD in water-stressed pines is the first empirical support for this long hypothesized relationship. Our observations suggest that low levels of embolism are common in Aleppo pine trees at the dry edge of their distribution.

Nitrogen uptake and macronutrients distribution in mango (Mangifera indica L. cv. Keitt) trees

We assessed the effects of N fertigation regime on nutrient uptake and distribution in leaves and fruit of mango cv. Keitt grown in a lysimeter for four years. We applied three treatments: N1 - no N fertilization (less than 2 mg/L in the tap water); N2 - 10 mg/L N; and N3 - 20 mg/L N. Deficient N conditions (N1) resulted in low vegetation and fruit yield, high fruit:leaf ratio, high photosynthetic activity, high leaf P and K concentrations, as well as high sugar content and low acidity in the fruit. Excess N concentration (N3) enhanced vegetative growth and reduced fruit yield and gas exchange. The calculated annual nitrogen uptake heavily depended on the nitrogen supply, being highest for the N2 treatment (196 g/tree) as compared with the N1 (25 g/tree) or N3 (185 g/tree) treatments. Fruits were a major N sink being 82% (in N1), 26% (in N2), and 5% (in N3) of the total annual N supplied. The N accumulation rate in the fruit of the N1 and N2 treatment were above the N quantities supplied via fertigation, suggesting that N reserve in the vegetative tissues supplied the fruit's high N demand. These findings highlight the link between mango's N requirements and fruit yield, as well as the risks of excessive N fertilization.

Stomatal responses in grapevine become increasingly more tolerant to low water potentials throughout the growing season

The leaf of a deciduous species completes its life cycle in a few months. During leaf maturation, osmolyte accumulation leads to a significant reduction of the turgor loss point (Ψ_TLP ), a known marker for stomatal closure. Here we exposed two grapevine cultivars to drought at three different times during the growing season to explore if the seasonal decrease in leaf Ψ_TLP influences the stomatal response to drought. The results showed a significant seasonal shift in the response of stomatal conductance to stem water potential (g_s ~Ψ_stem ), demonstrating that grapevines become increasingly tolerant to low Ψ_stem as the season progresses in coordination with the decrease in Ψ_TLP . We also used the SurEau hydraulic model to demonstrate a direct link between osmotic adjustment and the plasticity of g_s ~Ψ_stem . To understand the possible advantages of g_s ~Ψ_stem plasticity, we incorporated a seasonally dynamic leaf osmotic potential into the model that simulated stomatal conductance under several water availabilities and climatic scenarios. The model demonstrated that a seasonally dynamic stomatal closure threshold results in trade-offs: it reduces the time to turgor loss under sustained long-term drought, but increases overall gas exchange particularly under seasonal shifts in temperature and stochastic water availability. A projected hotter future is expected to lower the increase in gas exchange that plants gain from the seasonal shift in g_s ~Ψ_stem . These findings show that accounting for dynamic stomatal regulation is critical for understanding drought tolerance.

Gender differences in multifidus fatty infiltration, sarcopenia and association with preoperative pain and functional disability in patients with lumbar spinal stenosis

BACKGROUND

In patients with lumbar spinal stenosis, female gender has been associated with higher pain and functional disability. Sarcopenia and multifidus atrophy have also been associated with symptomatic severity.

PURPOSE

The purpose of this study was to determine if gender differences in sarcopenia and multifidus atrophy are associated with gender disparities in disease symptomatology.

STUDY DESIGN

Prospectively collected medical records and imaging studies were retrospectively reviewed.

PATIENT SAMPLE

We retrospectively reviewed medical records and imaging studies for 63 patients with clinically and radiologically defined lumbar spinal stenosis at L3/4 or L4/5 who underwent minimally invasive decompression.

OUTCOME MEASURES

Pain and functional disability were measured using the Oswestry Disability Index (ODI) and visual analogue scores for back pain (VASB) and leg pain (VASL).

METHODS

Multifidus total cross sectional area (tCSA), multifidus functional cross sectional area (fnCSA), multifidus fatty infiltration (FI), psoas tCSA, and psoas relative cross sectional area (rCSA) were evaluated by univariable and multivariable regression to identify gender linked and gender independent predictors of higher ODI, VASB, and VASL.

RESULTS

Female gender was significantly associated with lower multifidus fnCSA (p < .001), higher multifidus FI (p < .001), lower psoas tCSA (p < .001), lower psoas rCSA (p = .002), and higher preoperative ODI (p = .008). Lower psoas rCSA (p = .044) and psoas tCSA in the lowest sex specific quartile (p = .034) were significantly associated with higher preoperative VASB and psoas rCSA less than the sex specific median (p = .050) was significantly associated with higher preoperative VASL after controlling for age and gender. Multifidus FI was significantly associated with preoperative ODI after adjusting for age (p = .048) but not after controlling additionally for gender (p = .651).

CONCLUSIONS

Female patients with lumbar spinal stenosis may develop more severe and functionally significant multifidus atrophy, resulting in a more severe clinical course with higher functional disability. Sarcopenia was significantly associated with higher preoperative back pain and leg pain in both male and female patients with lumbar spinal stenosis.

Temporal Summation Predicts De Novo Contralateral Pain After Cordotomy in Patients With Refractory Cancer Pain

BACKGROUND

Percutaneous cervical cordotomy (PCC), which selectively interrupts ascending nociceptive pathways in the spinal cord, can mitigate severe refractory cancer pain. It has an impressive success rate, with most patients emerging pain-free. Aside from the usual complications of neurosurgical procedures, the risks of PCC include development of contralateral pain, which is less understood.

OBJECTIVE

To evaluate whether sensory and pain sensitivity, as measured by quantitative sensory testing (QST), are associated with PCC clinical outcomes.

METHODS

Fourteen palliative care cancer patients with severe chronic refractory pain limited mainly to one side of the body underwent comprehensive quantitative sensory testing assessment pre-PPC and post-PCC. They were also queried about maximal pain during the 24 h precordotomy (0-10 numerical pain scale).

RESULTS

All 14 patients reported reduced pain postcordotomy, with 7 reporting complete resolution. Four patients reported de novo contralateral pain. Reduced sensitivity in sensory and pain thresholds to heat and mechanical stimuli was recorded on the operated side (P = .028). Sensitivity to mechanical pressure increased on the unaffected side (P = .023), whereas other sensory thresholds were unchanged. The presurgical temporal summation values predicted postoperative contralateral pain (r = 0.582, P = .037).

CONCLUSION

The development of contralateral pain in patients postcordotomy for cancer pain might be due to central sensitization. Temporal summation could serve as a potential screening tool to identify those who are most likely at risk to develop contralateral pain. Analysis of PCC affords a unique opportunity to investigate how a specific lesion to the nociceptive system affects pain processes.

Productivity versus drought adaptation in olive leaves: Comparison of water relations in a modern versus a traditional cultivar

The physiological traits that set the tradeoff between productivity and drought adaptation in plants are still under debate. To reveal these traits, we compared the water relations of two olive (Olea europaea) cultivars: "Barnea"-a highly productive modern cultivar; and "Souri"-a drought-adapted traditional cultivar. We hypothesized that Souri has lower hydraulic conductivity and lower hydraulic vulnerability. The hypothesis was tested at the leaf level. The soil volumetric water content (θ), stem water potential (Ψ_S ), and gas exchange were measured in both cultivars while they dried until a significant reduction in their maximal photochemical potential (F_v /F_m  < 0.6) was obtained. Additionally, pressure-volume relations, leaf hydraulic vulnerability, and the petiole xylem architecture were evaluated. To our surprise, Souri's leaf hydraulic conductivity was more vulnerable to low Ψ_S , approaching zero at -8 MPa compared with <-10 MPa in "Barnea." At the same time, Souri's higher osmotic content and cell rigidity enabled it to sustain 1.4 MPa lower Ψ_S , while maintaining near optimal (F_v /F_m ). However, both cultivars significantly reduced their F_v /F_m (<0.6) at the same θ, suggesting that the capability to sustain a low θ is not the issue. Instead, Souri's lower transpiration enabled it to withstand a longer drought while avoiding low θ. Barnea's larger xylem vessels and hydraulic conductivity supported higher stomatal conductance (g_s ) and assimilation rate, which nurtured its higher productivity but resulted in quick depletion of θ. These results suggest that hydraulic resistance or the ability to sustain low θ do not set the tradeoff between productivity and drought adaptation in olive leaves.

A New Solution to an Old Problem: Ultrasound-guided Cervical Retrolaminar Injection for Acute Cervical Radicular Pain: Prospective Clinical Pilot Study and Cadaveric Study

STUDY DESIGN

Prospective clinical pilot study and cadaveric study.

OBJECTIVE

The aim of this study was to evaluate the spread of an ultrasound-guided interfascial plane blocks (UGIPBs) and its potential efficacy for cervical radiculopathy.

SUMMARY OF BACKGROUND DATA

Cervical radiculopathy is a common disorder, potentially leading to severe pain and disability. Conservative treatment with cervical epidural steroid injections (ESI) is limited by concerns regarding their safety. UGIPBs are used in cervical surgical procedures as part of the multimodal postoperative analgesia regimen however, were not described for cervical radiculopathy.

METHODS

Twelve patients with acute cervical radicular pain who failed conservative treatment and were candidates for surgery were offered a cervical retrolaminar injection. A solution of 4 mL lidocaine 0.5% and 10 mg dexamethasone was injected, assisted by ultrasound guidance, at the posterior aspect of the cervical lamina corresponding to the compressed nerve root level. Additionally, a cadaver study was carried to evaluate the contrast spread and infiltration into near structures, both anatomically and radiographically.

RESULTS

Twelve patients underwent the procedure, with a mean follow-up time of 14.5 weeks. Average numerical rating scale improved from 7.25 at baseline to 2.83 following the injection (P < 0.001). Three patients received 2 to 3 injections without significant improvement and were eventually operated. No adverse events were reported.In the cadaver study, fluoroscopy demonstrated contrast spread between T1 and T3 caudally, C2 to C5 cranially and facet joints laterally. Anatomically, the dye spread was demonstrated up to C2 cranially, T1 caudally, the articular pillars of C4 to C7, and the neural foramen of C6 laterally.

CONCLUSION

A solution injected into the cervical retrolaminar plane can diffuse in the cranial-caudal axis to C2-T3 and laterally to the facet joints and the cervical neural foramen. Our pilot study confirmed the feasibility of our study protocol. Future studies are needed to support our early results.Level of Evidence: 4.

Pain Management - A Decade's Perspective of a New Subspecialty

Objective

Pain management is increasingly recognized as a formal medical subspecialty worldwide. Israel was among the first to offer a board-certified subspecialty, formalized by the Israeli Medical Association in 2010 which is open to all clinicians with a state-recognized specialization. This paper aims at evaluating the current program across several quality control measures.

Design

A survey among pain medicine specialists who graduated from the Israeli Pain Management subspecialty.

Methods

All 43 graduates of the program were sent a web-based questionnaire, each related to a different time in the participants' residency period - prior to, during and after training.

Results

Forty-one physicians responded to the survey (95% response rate). The most common primary specialty was Anesthesiology (44%), followed by Family Medicine (22%). One-third of the respondents applied to the program over five years after completing their initial residency. Two-thirds reported that they acquired all or most of the professional tools required by a pain specialist. Insufficient training was mentioned regarding addiction management (71%), special population needs (54%) and interventional treatment (37%). A high proportion (82%) responded that the examination contributed to their training and almost all perceived their period of subspecialty as having a positive value in their personal development. Two-thirds of respondents had not yet actively engaged beyond the clinical aspect with other entities responsible for formulating guidelines and other strategic decision-making.

Conclusion

We hope the findings of this first-of-a-kind survey will encourage other medical authorities to construct formal training in pain medicine and enable this discipline to further evolve.

Cervical Cordotomy for Intractable Pain: Do Postoperative Imaging Features Correlate with Pain Outcomes and Mirror Pain?

BACKGROUND AND PURPOSE

Percutaneous cervical cordotomy offers relief of unilateral intractable oncologic pain. We aimed to find anatomic and postoperative imaging features that may correlate with clinical outcomes, including pain relief and postoperative contralateral pain.

MATERIALS AND METHODS

We prospectively followed 15 patients with cancer who underwent cervical cordotomy for intractable pain during 2018 and 2019 and underwent preoperative and up to 1-month postoperative cervical MR imaging. Lesion volume and diameter were measured on T2-weighted imaging and diffusion tensor imaging (DTI). Lesion mean diffusivity and fractional anisotropy values were extracted. Pain improvement up to 1 month after surgery was assessed by the Numeric Rating Scale and Brief Pain Inventory.

RESULTS

All patients reported pain relief from 8 (7-10) to 0 (0-4) immediately after surgery (P = .001), and 5 patients (33%) developed contralateral pain. The minimal percentages of the cord lesion volume required for pain relief were 10.0% on T2-weighted imaging and 6.2% on DTI. Smaller lesions on DWI correlated with pain improvement on the Brief Pain Inventory scale (r = 0.705, P = .023). Mean diffusivity and fractional anisotropy were significantly lower in the ablated tissue than contralateral nonlesioned tissue (P = .003 and P = .001, respectively), compatible with acute-phase tissue changes after injury. Minimal postoperative mean diffusivity values correlated with an improvement of Brief Pain Inventory severity scores (r = -0.821, P = .004). The average lesion mean diffusivity was lower among patients with postoperative contralateral pain (P = .037).

CONCLUSIONS

Although a minimal ablation size is required during cordotomy, larger lesions do not indicate better outcomes. DWI metrics changes represent tissue damage after ablation and may correlate with pain outcomes.

An increase in xylem embolism resistance of grapevine leaves during the growing season is coordinated with stomatal regulation, turgor loss point and intervessel pit membranes

Although xylem embolism resistance is traditionally considered as static, we hypothesized that in grapevine (Vitis vinifera) leaf xylem becomes more embolism-resistant over the growing season. We evaluated xylem architecture, turgor loss point (Ψ_TLP ) and water potentials leading to 25% of maximal stomatal conductance (g_s25 ) or 50% embolism in the leaf xylem (P₅₀ ) in three irrigation treatments and at three time points during the growing season, while separating the effects of leaf age and time of season. Hydraulic traits acclimated over the growing season in a coordinated manner. Without irrigation, Ψ_TLP , g_s25 , and P₅₀ decreased between late May and late August by 0.95, 0.77 and 0.71 MPa, respectively. A seasonal shift in P₅₀ occurred even in mature leaves, while irrigation had only a mild effect (< 0.2 MPa) on P₅₀ . Vessel size and pit membrane thickness were also seasonally dynamic, providing a plausible explanation for the shift in P₅₀ . Our findings provide clear evidence that grapevines can modify their hydraulic traits along a growing season to allow lower xylem water potential, without compromising gas exchange, leaf turgor or xylem integrity. Seasonal changes should be considered when modeling ecosystem vulnerability to drought or comparing datasets acquired at different phenological stages.

Interventional Pain Management for Cancer Pain: An Analysis of Outcomes and Predictors of Clinical Response

Background: Interventional procedures are offered routinely to patients seen in McGill University’s interdisciplinary cancer pain management program. However, publications on these procedures are scarce, making it difficult to predict which patients may benefit from them. Objectives: We hypothesized that interventional pain procedures offered to cancer patients could provide relief of pain as well as other symptoms. Furthermore, some variables may predict the efficacy of such procedures. Study Design: We conducted a retrospective chart review of interventional pain management procedures. Setting: The procedures reviewed were conducted at the Cancer Pain Program and performed at the interventional suites of the McGill University Health Centre. Methods: The retrospective chart review included interventional pain management procedures performed between June 2015 and March 2017. Demographic data, details about the underlying cancer and about the procedure and peripTrocedural patients’ reported outcomes were recorded for analysis. Results: Eighty-two of 126 procedures were included for analysis. Most patients presented with metastatic disease (75%). Eighty percent of the patients reported pain relief, with the average pain severity decreasing by more than 2 points on a 0-to-10 Numeric Rating Scale for pain (from 6.5 of 10 to 4.2 of 10). Forty-three percent of patients were considered responders (≥ 50% pain relief). Responders also reported a significant decrease in fatigue, depression, anxiety, drowsiness, and improved well-being. Among responders, average daily opioid use decreased significantly, by 60% on average. None of the analyzed variables correlated with the response; however, psychosocial variables like anxiety and depression showed a nonsignificant trend towards predicting procedure failure. Limitations: The core limitations of this study are its size and retrospective nature. Conclusions: In this cohort of cancer pain patients, interventional cancer pain procedures provided effective pain relief and other benefits, including pain relief, reduced burden of symptoms, and reduction of opioid intake, while demonstrating a favorable safety profile. Patients with poorer ratings of depression and fatigue derived less benefit from procedures, suggesting that offering such procedures as part of patients’ treatment plan would be sensible, rather than leaving interventions for later stages. Key words: Cancer pain, pain management, pain intractable, treatment outcomes, palliative care, advanced cancer, cancer, evidence-based madicine

Interventional Pain Management for Cancer Pain: An Analysis of Outcomes and Predictors of Clinical Response

BACKGROUND

Interventional procedures are offered routinely to patients seen in McGill University's interdisciplinary cancer pain management program. However, publications on these procedures are scarce, making it difficult to predict which patients may benefit from them.

OBJECTIVES

We hypothesized that interventional pain procedures offered to cancer patients could provide relief of pain as well as other symptoms. Furthermore, some variables may predict the efficacy of such procedures.

STUDY DESIGN

We conducted a retrospective chart review of interventional pain management procedures.

SETTING

The procedures reviewed were conducted at the Cancer Pain Program and performed at the interventional suites of the McGill University Health Centre.

METHODS

The retrospective chart review included interventional pain management procedures performed between June 2015 and March 2017. Demographic data, details about the underlying cancer and about the procedure and peripTrocedural patients' reported outcomes were recorded for analysis.

RESULTS

Eighty-two of 126 procedures were included for analysis. Most patients presented with metastatic disease (75%). Eighty percent of the patients reported pain relief, with the average pain severity decreasing by more than 2 points on a 0-to-10 Numeric Rating Scale for pain (from 6.5 of 10 to 4.2 of 10). Forty-three percent of patients were considered responders (>= 50% pain relief). Responders also reported a significant decrease in fatigue, depression, anxiety, drowsiness, and improved well-being. Among responders, average daily opioid use decreased significantly, by 60% on average. None of the analyzed variables correlated with the response; however, psychosocial variables like anxiety and depression showed a nonsignificant trend towards predicting procedure failure.

LIMITATIONS

The core limitations of this study are its size and retrospective nature.

CONCLUSIONS

In this cohort of cancer pain patients, interventional cancer pain procedures provided effective pain relief and other benefits, including pain relief, reduced burden of symptoms, and reduction of opioid intake, while demonstrating a favorable safety profile. Patients with poorer ratings of depression and fatigue derived less benefit from procedures, suggesting that offering such procedures as part of patients' treatment plan would be sensible, rather than leaving interventions for later stages.

The physiology of drought stress in grapevine: towards an integrative definition of drought tolerance

Water availability is arguably the most important environmental factor limiting crop growth and productivity. Erratic precipitation patterns and increased temperatures resulting from climate change will likely make drought events more frequent in many regions, increasing the demand on freshwater resources and creating major challenges for agriculture. Addressing these challenges through increased irrigation is not always a sustainable solution so there is a growing need to identify and/or breed drought-tolerant crop varieties in order to maintain sustainability in the context of climate change. Grapevine (Vitis vinifera), a major fruit crop of economic importance, has emerged as a model perennial fruit crop for the study of drought tolerance. This review synthesizes the most recent results on grapevine drought responses, the impact of water deficit on fruit yield and composition, and the identification of drought-tolerant varieties. Given the existing gaps in our knowledge of the mechanisms underlying grapevine drought responses, we aim to answer the following question: how can we move towards a more integrative definition of grapevine drought tolerance?

Leaf Carbon Export and Nonstructural Carbohydrates in Relation to Diurnal Water Dynamics in Mature Oak Trees

Trees typically experience large diurnal depressions in water potential, which may impede carbon export from leaves during the day because the xylem is the source of water for the phloem. As water potential becomes more negative, higher phloem osmotic concentrations are needed to draw water in from the xylem. Generating this high concentration of sugar in the phloem is particularly an issue for the ∼50% of trees that exhibit passive loading. These ideas motivate the hypothesis that carbon export in woody plants occurs predominantly at night, with sugars that accumulate during the day assisting in mesophyll turgor maintenance or being converted to starch. To test this, diurnal and seasonal patterns of leaf nonstructural carbohydrates, photosynthesis, solute, and water potential were measured, and carbon export was estimated in leaves of five mature (>20 m tall) red oak (Quercus rubra) trees, a species characterized as a passive loader. Export occurred throughout the day at equal or higher rates than at night despite a decrease in water potential to -1.8 MPa at midday. Suc and starch accumulated over the course of the day, with Suc contributing ∼50% of the 0.4 MPa diurnal osmotic adjustment. As a result of this diurnal osmotic adjustment, estimates of midday turgor were always >0.7 MPa. These findings illustrate the robustness of phloem functioning despite diurnal fluctuations in leaf water potential and the role of nonstructural carbohydrates in leaf turgor maintenance.

Tailoring of neurosurgical ablative procedures in the management of refractory cancer pain

INTRODUCTION

Neurosurgical ablative procedures can offer immediate and effective pain relief for patients suffering from refractory cancer pain. However, choosing the appropriate procedure for each patient may not be straightforward and warrants an interdisciplinary approach. The purpose of the current study was to evaluate the outcome of patients with cancer who were carefully selected for neurosurgical intervention by a dedicated interdisciplinary team composed of a palliative physician and nurse practitioner, a pain specialist and a neurosurgeon.

METHODS

A retrospective review was carried out on all patients who underwent neurosurgical ablative procedures in our institute between March 2015 and September 2019. All patients had advanced metastatic cancer with unfavorable prognosis and suffered from intractable oncological pain. Each treatment plan was devised to address the patients' specific pain syndromes.

RESULTS

A total of 204 patients were examined by our service during the study period. Sixty-four patients with localized pain and nineteen patients with diffuse pain syndromes were selected for neurosurgical interventions, either targeted disconnection of the spinothalamic tract or stereotactic cingulotomy. Substantial pain relief was reported by both groups immediately (cordotomy: Numerical Rating Scale (NRS) 9 ≥1, p=0.001, cingulotomy: NRS 9 ≥2, p=0.001) and maintained along the next 3-month follow-up visits.

CONCLUSIONS

An interdisciplinary collaboration designated to provide neurosurgical ablative procedures among carefully selected patients could culminate in substantial relief of intractable cancer pain.

TRIAL REGISTRATION NUMBER

IR0354-17.

Visualizing Embolism Propagation in Gas-Injected Leaves

Because the xylem in leaves is thought to be at the greatest risk of cavitation, reliable and efficient methods to characterize leaf xylem vulnerability are of interest. We report a method to generate leaf xylem vulnerability curves (VCs) by gas injection. Using optical light transmission, we visualized embolism propagation in grapevine (Vitis vinifera) and red oak (Quercus rubra) leaves injected with positive gas pressure. This resulted in a rapid, stepwise reduction of transmitted light, identical to that observed during leaf dehydration, confirming that the optical method detects gas bubbles and provides insights into the air-seeding hypothesis. In red oak, xylem VCs generated using gas injection were similar to those generated using bench dehydration, but indicated 50% loss of conductivity at lower tension (∼0.4 MPa) in grapevine. In determining VC, this method eliminates the need to ascertain xylem tension, thus avoiding potential errors in water potential estimations. It is also much faster (1 h per VC). However, severing the petiole and applying high-pressure gas could affect air-seeding and the generated VC. We discuss potential artifacts arising from gas injection and recommend comparison of this method with a more standard procedure before it is assumed to be suitable for a given species.

Neurosurgical ablative procedures for intractable cancer pain

OBJECTIVE

Cancer patients suffering from severe refractory pain may benefit from targeted ablative neurosurgical procedures aimed to disconnect pain pathways in the spinal cord or the brain. These patients often present with a plethora of medical problems requiring careful consideration before surgical interventions. The authors present their experience at an interdisciplinary clinic aimed to facilitate appropriate patient selection for neurosurgical procedures, and the outcome of these interventions.

METHODS

This study was a retrospective review of all patients who underwent neurosurgical interventions for cancer pain in the authors' hospital between March 2015 and April 2018. All patients had advanced metastatic cancer with limited life expectancy and suffered from intractable oncological pain.

RESULTS

Sixty patients underwent surgery during the study period. Forty-three patients with localized pain underwent disconnection of the spinal pain pathways: 34 percutaneous-cervical and 5 open-thoracic cordotomies, 2 stereotactic mesencephalotomies, and 2 midline myelotomies. Thirty-nine of 42 patients (93%) who completed these procedures had excellent immediate postoperative pain relief. At 1 month the improvement was maintained in 30/36 patients (83%) available for follow-up. There was 1 case of hemiparesis.Twenty patients with diffuse pain underwent stereotactic cingulotomy. Nineteen of these patients reported substantial pain relief immediately after the operation. At 1 month good pain relief was maintained in 13/17 patients (76%) available for follow-up, and good pain relief was also found at 3 months in 7/11 patients (64%). There was no major morbidity or mortality.

CONCLUSIONS

With careful patient selection and tailoring of the appropriate procedure to the patient's pain syndrome, the authors' experience indicates that neurosurgical procedures are safe and effective in alleviating suffering in patients with intractable cancer pain.

Swift metabolite changes and leaf shedding are milestones in the acclimation process of grapevine under prolonged water stress

BACKGROUND

Grape leaves provide the biochemical substrates for berry development. Thus, understanding the regulation of grapevine leaf metabolism can aid in discerning processes fundamental to fruit development and berry quality. Here, the temporal alterations in leaf metabolism in Merlot grapevine grown under sufficient irrigation and water deficit were monitored from veraison until harvest.

RESULTS

The vines mediated water stress gradually and involving multiple strategies: osmotic adjustment, transcript-metabolite alteration and leaf shedding. Initially stomatal conductance and leaf water potential showed a steep decrease together with the induction of stress related metabolism, e.g. up-regulation of proline and GABA metabolism and stress related sugars, and the down-regulation of developmental processes. Later, progressive soil drying was associated with an incremental contribution of Ca²⁺ and sucrose to the osmotic adjustment concomitant with the initiation of leaf shedding. Last, towards harvest under progressive stress conditions following leaf shedding, incremental changes in leaf water potential were measured, while the magnitude of perturbation in leaf metabolism lessened.

CONCLUSIONS

The data present evidence that over time grapevine acclimation to water stress diversifies in temporal responses encompassing the alteration of central metabolism and gene expression, osmotic adjustments and reduction in leaf area. Together these processes mitigate leaf water stress and aid in maintaining the berry-ripening program.

New frontier: cancer pain management clinical fellowship

Cancer pain is a multi-dimensional experience, varies from person to person both physically and psycho-socially, and impacts all aspects of the patients' quality of life. Majority of patients with an advanced or metastatic cancer will experience pain. It is estimated that as many as half of cancer patients are under-treated and as many as 20% experience pain refractory to the conventional WHO ladder of pain management. The McGill University Health Centre (MUHC) Cancer Pain Clinic (CPC) was created to meet the needs of those patients with a diagnosis of cancer whose pain had become a main symptom and those who failed to respond to conventional treatment. The clinic offers a unique interdisciplinary approach with a core team that includes an anesthesiologist, a palliative care physician, a radiation oncologist, a nurse clinician specialist in oncology and palliative care, and, recently, also an interventional radiologist. A cancer pain clinical fellowship was offered for the first time in July 2016. It provides intense training in the classification, epidemiology, pathophysiology, and treatment of cancer pain. Through our education program, the fellow learns to appreciate, weigh, and respond to the full spectrum of factors influencing a specific patient's condition and to develop a tailor-made care plan. To our knowledge, it is the only fellowship program in existence that focuses exclusively on cancer pain. We see it as a beacon and hope that our graduate fellows become professional leaders with a quest not only to provide the best possible care but also to raise awareness of the humanitarian need to control cancer pain.

[NEUROSURGICAL INTERVENTIONS FOR INTRACTABLE ONCOLOGICAL PAIN]

Pain is one of the most common symptoms among cancer patients, and particularly in those who suffer from metastatic or terminal disease. There is great importance in delivering good pain management to these patients in order to alleviate their suffering, improve their functional status and their overall quality of life. In most cases, pain management is based on pharmacotherapy with opioids and other medications. However, there are selected patients for whom pharmacotherapy does not achieve acceptable pain relief or is associated with marked side effects. These patients, who suffer from refractory cancer pain, may benefit from neurosurgical procedures selectively intervening in different locations along the pain signaling pathways. This article summarizes several of these neurosurgical procedures: percutaneous cordotomy for unilateral pain, punctuate midline myelotomy for visceral pain and stereotactic cingulotomy for diffuse pain syndromes. This article demonstrates the use of careful patient selection by an interdisciplinary team which is critical for the success of these procedures. The team consists of palliative care specialists, pain specialists and a neurosurgeon. These neurosurgical interventions are presented through representative clinical cases, followed by a discussion of the clinical considerations that guided the choice of the therapeutic approach for each case.

Iso/Anisohydry: A Plant-Environment Interaction Rather Than a Simple Hydraulic Trait

Plants are frequently classified as isohydric or anisohydric in an attempt to portray their water relations strategy or ecological niche. However, despite the popularity of the iso/anisohydric classification, the underlying biology remains unclear. We use here a simple hydraulic model and the extensive literature on grapevine hydraulics to illustrate that the iso/anisohydric classification of a plant depends on the definition used and the environment in which it is grown, rather than describing an intrinsic property of the plant itself. We argue that abandoning the iso/anisohydric terminology and returning to a more fundamental hydraulic framework would provide a stronger foundation for species comparisons and ecological predictions.