Reduced plasma calcitonin gene-related peptide level identified in cluster headache: A prospective and controlled study

BACKGROUND

The role of calcitonin gene-related peptide (CGRP) in the cyclic pattern of cluster headache is unclear. To acquire biological insight and to comprehend why only episodic cluster headache responds to CGRP monoclonal antibodies, we examined whether plasma CGRP changes between disease states (i.e. bout, remission and chronic) and controls.

METHODS

The present study is a prospective case-control study. Participants with episodic cluster headache were sampled twice (bout and remission). Participants with chronic cluster headache and controls were sampled once. CGRP concentrations were measured in plasma with a validated radioimmunoassay.

RESULTS

Plasma was collected from 201 participants diagnosed with cluster headache according to the International Classification of Headache Disorders, 3rd edition, and from 100 age- and sex-matched controls. Overall, plasma CGRP levels were significantly lower in participants with cluster headache compared to controls (p < 0.05). In episodic cluster headache, CGRP levels were higher in bout than in remission (mean difference: 17.1 pmol/L, 95% confidence interval = 9.8-24.3, p < 0.0001). CGRP levels in bout were not different from chronic cluster headache (p = 0.266).

CONCLUSIONS

Plasma CGRP is unsuitable as a diagnostic biomarker of cluster headache or its disease states. The identified reduced CGRP levels suggest that CGRPs role in cluster headache is highly complex and future investigations are needed into the modulation of CGRP and its receptors.

The ATP sensitive potassium channel (KATP) is a novel target for migraine drug development

Migraine is one of the leading causes of disability worldwide, affecting work and social life. It has been estimated that sales of migraine medicines will reach 12.9 billion USD in 2027. To reduce social impact, migraine treatments must improve, and the ATP-sensitive potassium (K_ATP) channel is a promising target because of the growing evidence of its implications in the pathogenesis of migraine. Strong human data show that opening of the K_ATP channel using levcromakalim is the most potent headache and migraine trigger ever tested as it induces headache in almost all healthy subjects and migraine attacks in 100% of migraine sufferers. This review will address the basics of the K_ATP channel together with clinical and preclinical data on migraine implications. We argue that K_ATP channel blocking, especially the Kir6.1/SUR2B subtype, may be a target for migraine drug development, however translational issues remain. There are no human data on the closure of the K_ATP channel, although blocking the channel is effective in animal models of migraine. We believe there is a good likelihood that an antagonist of the Kir6.1/SUR2B subtype of the K_ATP channel will be effective in the treatment of migraine. The side effects of such a blocker may be an issue for clinical use, but the risk is likely only moderate. Future clinical trials of a selective Kir6.1/SUR2B blocker will answer these questions.

Role of PACAP in migraine: An alternative to CGRP?

Migraine is a widespread and debilitating neurological condition affecting more than a billion people worldwide. Thus, more effective migraine therapies are highly needed. In the last decade, two endogenous neuropeptides, calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide (PACAP), were identified to be implicated in migraine. Recently, introduction of monoclonal antibodies (mAbs) blocking the CGRP is the most important advance in migraine therapy for decades. However, 40% of patients are unresponsive to these new drugs. We believe that PACAP may be involved in these patients. Like CGRP, PACAP is located to sensory nerve fibers, it dilates cranial arteries, it causes migraine when infused into patients and it is a peptide that lends itself to antibody therapy. Also, recent studies suggest that the PACAP pathway is independent of the CGRP pathway. Understanding the signaling pathways of PACAP may therefore lead to identification of novel therapeutic targets of particular interest in patients unresponsive to anti-CGRP therapy. Accordingly, neutralizing mAb to PACAP is currently in clinical phase II development. The aim of the present review is, therefore, to give a thorough account of the existing data on PACAP, its receptors and its relation to migraine.

PACAP signaling is not involved in GTN- and levcromakalim-induced hypersensitivity in mouse models of migraine

BACKGROUND

Calcitonin gene-related peptide (CGRP) antagonizing drugs represents the most important advance in migraine therapy for decades. However, these new drugs are only effective in 50-60% of patients. Recent studies have shown that the pituitary adenylate cyclase-activating peptide (PACAP38) pathway is independent from the CGRP signaling pathway. Here, we investigate PACAP38 signaling pathways in relation to glyceryl trinitrate (GTN), levcromakalim and sumatriptan.

METHODS

In vivo mouse models of PACAP38-, GTN-, and levcromakalim-induced migraine were applied using tactile sensitivity to von Frey filaments as measuring readout. Signaling pathways involved in the three models were dissected using PACAP-inhibiting antibodies (mAbs) and sumatriptan.

RESULTS

We showed that PACAP mAbs block PACAP38 induced hypersensitivity, but not via signaling pathways involved in GTN and levcromakalim. Also, sumatriptan has no effect on PACAP38-induced hypersensitivity relevant to migraine. This is the first study testing the effect of a PACAP-inhibiting drug on GTN- and levcromakalim-induced hypersensitivity.

CONCLUSIONS

Based on the findings in our mouse model of migraine using migraine-inducing compounds and anti-migraine drugs, we suggest that PACAP acts via a distinct pathway. Using PACAP38 antagonism may be a novel therapeutic target of interest in a subgroup of migraine patients who do not respond to existing therapies.

Von Frey testing revisited: Provision of an online algorithm for improved accuracy of 50% thresholds

BACKGROUND

In the pain field, it is essential to quantify nociceptive responses. The response to the application of von Frey filaments to the skin measures tactile sensitivity and is a surrogate marker of allodynia in states of peripheral and/or central sensitization. The method is widely used across species within the pain field. However, uncertainties appear to exist regarding the appropriate method for analysing obtained data. Therefore, there is a need for refinement of the calculations for transformation of raw data to quantifiable data.

METHODS

Here, we briefly review the fundamentals behind von Frey testing using the standard up-down method and the associated statistics and show how different parameters of the statistical equation influence the calculated 50% threshold results. We discuss how to obtain the most accurate estimations in a given experimental setting.

RESULTS

To enhance accuracy and reproducibility across laboratories, we present an easy to use algorithm that calculates 50% thresholds based on the exact filaments and their interval using math beyond the traditional methods. This tool is available to the everyday user of von Frey filaments and allows the insertion of all imaginable ranges of filaments and is thus applicable to data derived in any species.

CONCLUSION

We advocate for the use of this algorithm to minimize inaccuracies and to improve internal and external reproducibility.

SIGNIFICANCE

The von Frey testing procedure is standard for assessing peripheral and central sensitization but is associated with inaccuracies and lack of transparency in the associated math. Here, we describe these problems and present a novel statistical algorithm that calculates the exact thresholds using math beyond the traditional methods. The online platform is transparent, free of charge and easy to use also for the everyday user of von Frey filaments. Application of this resource will ultimately reduce errors due to methodological misinterpretations and increase reproducibility across laboratories.

Cilostazol induces C-fos expression in the trigeminal nucleus caudalis and behavioural changes suggestive of headache with the migraine-like feature photophobia in female rats

Introduction

Research in development of new migraine therapeutics is hindered by the lack of suitable, predictive animal models. Cilostazol provokes headache in healthy humans and migraineurs by increasing intracellular cAMP levels. We aimed to investigate whether cilostazol could provoke headache-like behaviours and c-fos expression in rats. In order to evaluate the predictive validity of the model, we examined the response to the migraine specific drug sumatriptan.

Methods

The effect of cilostazol (125 mg/kg p.o.) in female Sprague Dawley rats was evaluated on a range of spontaneous behavioural parameters, light sensitivity and mechanical sensitivity thresholds. We also measured c-fos expression in the trigeminal nucleus caudalis.

Results

Cilostazol increased light sensitivity and grooming behaviour. These manifestations were not inhibited by sumatriptan. Cilostazol also induced c-fos expression in the trigeminal nucleus caudalis. Furthermore, trigeminal – but not hind paw hyperalgesia was observed.

Conclusion

The altered behaviours are suggestive of cilostazol induced headache with migraine-like features, but not specific. The presence of head specific hyperalgesia and the c-fos response in the trigeminal nucleus caudalis imply that the model involves trigeminal nociception. The model will be useful for studying mechanisms related to the cAMP pathway in headache, but its predictive properties appear to be more limited due to the lack of response to sumatriptan.

Generation and detection of a sub-Poissonian atom number distribution in a one-dimensional optical lattice

We demonstrate preparation and detection of an atom number distribution in a one-dimensional atomic lattice with the variance -14  dB below the Poissonian noise level. A mesoscopic ensemble containing a few thousand atoms is trapped in the evanescent field of a nanofiber. The atom number is measured through dual-color homodyne interferometry with a pW-power shot noise limited probe. Strong coupling of the evanescent probe guided by the nanofiber allows for a real-time measurement with a precision of ±8  atoms on an ensemble of some 10(3)  atoms in a one-dimensional trap. The method is very well suited for generating collective atomic entangled or spin-squeezed states via a quantum nondemolition measurement as well as for tomography of exotic atomic states in a one-dimensional lattice.

The role of police dogs as companions and working partners

Written responses to a questionnaire by 255 officers who used canines in police work were assessed. Almost all officers frequently played with, talked to, petted, and brushed their dogs and believed the dogs benefitted their health and well-being. Officers whose dogs slept indoors, often in the same bedroom, generally said they loved their dogs and they described their dogs as calm rather than active, as indicated by a multiple correspondence analysis. These 96 officers more than the 154 officers whose dogs slept outdoors or in kennels also planned to remain in canine work. Although departments often assumed responsibility for purchasing the dogs, the more experienced officers usually were involved in the final selection of dogs (logistic regression: p < .0001). Compared with 94 officers not involved in selecting their dogs, 106 officers with a specific role in selecting their dogs planned to stay in canine work, as shown by a multiple correspondence analysis. They believed the dogs had saved their lives (p < .01). Over-all, officers reported spending 4.1 hr. on-duty and 2.9 hr. off-duty per week training their dogs, and also played with them for 6.5 hr. per week, assuring a regular pattern of exercise for the officers. Virtually all officers valued canine service and believed the dogs enhanced the department's effectiveness. This study showed that both close companionship with the dog and involvement in selecting the dog were associated both with satisfaction with the dog and with working as a canine officer.

Placebo-controlled trial of intravaginal clindamycin 2% cream for the treatment of bacterial vaginosis

OBJECTIVE

To compare the safety and efficacy of intravaginal clindamycin 2% cream with placebo in nonpregnant women with bacterial vaginosis.

DESIGN

A randomized, double-blind, placebo-controlled clinical trial.

SETTING

Ambulatory patients in the general community.

PATIENTS

Two hundred fifteen nonpregnant outpatients with a diagnosis of bacterial vaginosis were entered into this study. Of the 134 evaluable patients, 65 received clindamycin and 69 placebo. Demographic parameters were comparable between the two treatment groups.

INTERVENTION

Study subjects were equally randomized to receive either 5 g of clindamycin 2% vaginal cream or placebo cream for seven nights.

MAIN OUTCOME MEASURES

Clinical and microbiologic follow-up evaluations were scheduled for 5-10 days and 25-39 days posttreatment. Patients were interviewed about signs and symptoms, adverse events, and compliance. Diagnostic examinations were performed.

RESULTS

Clinical success rates (cure and improvement) occurred in 50 of 65 patients who received clindamycin (77 percent) and 17 of 69 patients who received placebo (25 percent) by the first posttreatment visit (p < 0.001). Microbiologic cures or improvement were observed in 59 of the 65 patients treated with clindamycin (91 percent) compared with 20 of 69 placebo-treated patients (29 percent) (p < 0.001). At the end of the study, clinical and microbiologic cures or improvement were evident in 45 of 57 (79 percent) and 37 of 57 clindamycin-treated patients (65 percent), respectively, and 18 of 51 (35 percent) and 14 of 51 (28 percent) of the placebo-treated patients, respectively. The success rates with clindamycin 2% cream were statistically higher than those with placebo. The adverse-effect profiles in the two groups were similar and no serious adverse effects were reported. Patients who received clindamycin had a statistically higher incidence of nonbacterial vaginitis/cervicitis (18.5 vs. 7.5 percent, p = 0.003).

CONCLUSIONS

Intravaginal clindamycin 2% cream appears to be an effective and safe treatment of symptomatic bacterial vaginosis in nonpregnant women.

Serum creatinine level and renal function in children

OBJECTIVE

To evaluate the accuracy of serum creatinine and height/serum creatinine glomerular filtration rate (Cr-GFR) formula as screening tests for abnormal renal function defined by plasma diethylenetriaminepenta-acetic acid (DTPA) clearance.

DESIGN

Patient series.

SETTING

The Children's Hospital of Buffalo (NY).

PATIENTS

Eighty-seven consecutive patients ranging in age from 2 to 20 years.

MEASUREMENTS

The Cr-GFR was calculated by means of the formula GFR (milliliters per minute per 1.73 m2) = kL/serum creatinine (milligrams per deciliter), where L is body length in centimeters and k is a constant dependent on age and sex. Plasma clearance of technetium Tc 99m-labeled DTPA was our reference method for determination of GFR (DTPA-GFR).

RESULTS

The Cr-GFR formula identified children with impaired renal function (DTPA clearance, less than 80 mL/min per 1.73 m2) with a sensitivity of 95% and a specificity of 93%. In contrast, the sensitivity and specificity of elevated serum creatinine level for this purpose were 80% and 96%, respectively. Of the children with renal insufficiency (DTPA clearance, 40 to 79 mL/min per 1.73 m2), 91% were correctly identified by the Cr-GFR formula. However, only 65% of these children had elevated serum creatinine levels. Although all children with renal failure (DTPA clearance, less than 40 mL/min per 1.73 m2) had abnormally high serum creatinine levels, the specificity of this test was significantly lower than that of the Cr-GFR formula (75% vs 100%, respectively).

CONCLUSIONS

The Cr-GFR formula is superior to serum creatinine level for estimating GFR. This formula provides a simple, reasonably accurate screening test for the presence and severity of impaired renal function.

Isolated intrathoracic spleen presenting as an enlarging chest mass. CT and MRI findings

We present the first reported case of an isolated intrathoracic spleen. This presented as an enlarging chest mass in a 6-month-old infant. The lack of symptoms and absence of herniated bowel caused an interesting diagnostic problem which was elegantly solved by a combination of imaging modalities.