Hereditary Ataxias in Cuba: A Nationwide Epidemiological and Clinical Study in 1001 Patients

The Cerebellum - The prevalence estimations of hereditary ataxias are biased since most epidemiological studies are confined to isolated geographical regions and few nationwide studies are...     

The constrictor knot is the best ligature

Introduction

An ideal ligature should tighten readily and remain tight. Ligature failure can be a critical complication of invasive procedures in human and veterinary surgical practice. Previous studies have tested various knots but not the constrictor knot.

Methods

A new test bench was employed to compare six ligatures using four suture materials. As tension in a ligature is not readily measured, the study employed a surrogate measurement: the force required to slide a ligature along a rod. Benchmark values tested each suture material wrapped around the rod to establish the ratio between this force and the ligature tension for each material. Each ligature was tested first during tightening and then again afterwards. The benchmark ratios were employed to calculate the tensions to evaluate which ligature and which suture material retained tension best.

Results

The model provided consistent linear relationships between the tension in the suture and the force required to pull the ligature along the rod. The constrictor knot retained tension in the ligature best (55–107% better than the next best ligature). Among the suture materials, polydioxanone had the greatest ability to retain the tension in a ligature and polyglactin the least.

Conclusions

The constrictor knot showed superior characteristics for use as a ligature, and should be introduced into teaching and clinical practice for human and veterinary surgery. The new test bench is recommended for future testing of ligatures as well as objective comparison of suture materials.     

Comparison of patient reported outcomes after Triathlon? and Kinemax Plus prostheses

INTRODUCTION

The Triathlon^® (Stryker, Kalamazoo, MI, US) total knee replacement was designed to improve patient function and survivorship. The aim of this study was to determine whether the Triathlon^® prosthesis produces better patient reported outcomes than a previous design by the same manufacturer, the Kinemax Plus.

METHODS

The outcome of 233 knees of patients with a mean age of 68 years (range: 40–80 years) who received the Kinemax Plus prosthesis were compared with the outcomes of 220 knees of patients with a mean age of 70 years (range: 42–90 years) who received the Triathlon^® prosthesis. Data were collected via postal questionnaire prior to surgery as well as at 8–12 weeks and at 1 year following surgery. Validated questionnaires were used including the WOMAC^® (Western Ontario and McMaster Universities) pain and function scales, the Knee injury and Osteoarthritis Outcome Score quality of life scale and the self-administered patient satisfaction scale.

RESULTS

This study found that patients who had the Triathlon^® prosthesis had significantly better pain relief (p<0.0001), function (p=0.028), knee related quality of life (p<0.0001) and satisfaction (p=0.0003) at three months after surgery than those who received the Kinemax Plus prosthesis. In addition, knee related quality of life (p=0.002) and satisfaction (p=0.021) were significantly higher at one year after surgery in Triathlon^® patients.

CONCLUSIONS

The findings suggest that return to function and reduction in pain may occur more quickly in patients with a Triathlon^® prosthesis than in those with the Kinemax Plus.     

Methods for siting emergency stomas in the absence of a stoma therapist

Introduction

Stomas often have to be sited in emergencies by trainees who may have had little training in this. Emergency stomas and stomas where the site has not been marked preoperatively by a stoma therapist are more prone to complications. These complications may severely affect a patient’s quality of life. Advice in the literature on how to best site stomas is conflicting. We compared two easy anatomical methods of siting stomas to sites chosen by a stoma therapist and looked at how this site was affected by the patients’ body mass index (BMI).

Methods

Patients undergoing elective colorectal surgery were seen either pre or postoperatively. Each patient’s BMI was recorded and the positions of three different potential stoma positions (site G: the gold standard, marked by a stoma therapist; site S: marked using a pair of scissors against the umbilicus; site H: halfway between the umbilicus and anterior superior iliac spine) were compared.

Results

The two fixed anatomical methods described (method S and method H) both gave poor results. The most common reason for poor siting was the proximity of a skin crease. There was a statistically significant correlation between the patient’s BMI and the laterality of the gold standard site.

Conclusions

The two simple anatomical methods described here do not provide a shortcut to effective siting. A more effective method may be calculating the laterality of the site using the patient’s BMI, and then moving up/down to avoid a skin crease and improve the patient’s view for changing the bag. This deserves further study.     

Chagas' disease diagnosis: evaluation of several tests in blood bank screening

Blood transfusion is one of the principal routes of transmission of Chagas' disease, a major endemic disease in Latin America. Methods for blood screening are not accurate and may yield false results that lead to high social and economic costs. This study compares two methods of diagnosing Chagas' disease (indirect immunofluorescence and hemagglutination) and several enzyme-linked immunosorbent assays (ELISAs) with regard to specificity and sensitivity, by using human sera with known serologic and parasitologic characteristics, as well as samples with discrepant results on conventional serologic tests. An ELISA using recombinant antigens showed no cross-reactivity with sera that were positive for other diseases. All evaluated ELISAs performed well, and their use may lead to a reduction of more than 50 percent in the number of discordant sera. Further improvements are needed in view of the complexity of the serologic diagnosis of Chagas' disease.     

Naratriptan: biological profile in animal models relevant to migraine

The biological profile of naratriptan (N-methyl-3-(1-methyl-4-piperidinyl)-1H-indole-5-ethane-sulphona-mide), a novel 5HT_1B/1D receptor agonist, was investigated in a variety of experimental models of relevance to migraine. Naratriptan has high affinity for human recombinant 5HT_1B and 5HT_1D receptors (pKi = 8.70.03 and 8.30.1, respectively) and causes contractions of dog isolated basilar and middle cerebral artery (EC₅₀ values of 0.11 and 0.07 M, respectively). Naratriptan causes small contractions of human isolated coronary arteries (EC₅₀ value of 0.17 M; maximum contraction equivalent to 33% of 5HT maximum). In anaesthetized dogs, naratriptan causes selective vasoconstriction of the carotid arterial bed (CD₅₀ dose = 193 g kg⁻¹) and, in anaesthetized rats, naratriptan selectively inhibits neurogenic plasma protein extravasation in the dura (ID₅₀ = 4.1 g kg⁻¹). In a variety of antinociceptive tests, naratriptan has no effect even at high doses. In conscious rats and dogs, naratriptan has high oral bioavailability (71% and 95%, respectively). The data show that naratriptan is a selective agonist at 5HT_1B/1D receptors, with a pharmacological profile very similar to that of sumatriptan, albeit 2-3 fold more potent. These observations, coupled with high oral bioavailability in animals, suggest that naratriptan has the profile of an orally effective anti-migraine drug.     

The evaluation of the N-type channel blocking properties of cilnidipine and other voltage-dependent calcium antagonists

Sympathetic neurotransmission in tissues with intact sympathetic nerve arborization is extensively dependent on calcium influx via N-type calcium-channels. It was the objective of the present study to assess and compare the claimed sympatholytic effect of the 1,4-dihydropyridine compound cilnidipine with other voltage-dependent calcium-channel (VDCC) antagonists. We studied these compounds by means of three different models. In the rabbit isolated thoracic aorta, the alleged sympatholytic properties displayed by these compounds were evaluated in the noradrenaline spillover model. Additionally, the influence of cilnidipine on stimulation-induced constrictor responses was studied in the rat isolated tail artery (male Wistar rats, 250-300 g) in addition to its effect on noradrenaline-induced contractions. Finally, we studied the influence of cilnidipine and other calcium-channel blockers on stimulation-induced chronotropic responses, in order to address N- or L-type selectivity, in the pithed rat model (male Wistar rats, 260-320 g). Furthermore, we evaluated their effect on noradrenaline-induced tachycardia. In the isolated rabbit thoracic aorta preparation omega-conotoxin GVIA (0.1 microM) nearly abolished the sympathetic outflow caused by stimulation, whereas nifedipine (0.1 microM) and amlodipine (1 microM) did not influence the evoked noradrenaline release. Cilnidipine (1 microM) significantly attenuated the response by nearly 18% and mibefradil (1 microM) by c. 42%. The stimulation-induced constrictor response (prejunctional effect) in the rat isolated tail artery could be blocked by omega-conotoxin GVIA (0.5 and 1 microM). Cilnidipine (10 nm and 0.1 microM) significantly attenuated responses to stimulation by maximally 20%, whereas it did not influence the constrictor response to noradrenaline (postjunctional effect). The mean heart rate in the pithed rat model amounted to 309.3 +/- 3.6 beats/min (bpm). Electrical stimulation of the cardio-accelerator nerves (C7-Th1) resulted in an increase by 106.7 +/- 2.2 bpm. All antagonists studied, except for nifedipine, attenuated the chronotropic response to stimulation (P < 0.05). The rank order of sympatholytic efficacy was: omega-conotoxin GVIA (84.8%), mibefradil (75.1%), cilnidipine (43.0%) and amlodipine (34.8%). Noradrenaline (10 nmol/kg) increased the heart rate by 117.8 +/- 2.7 bpm. This chronotropic response was influenced equally well by the calcium-channels blockers as observed in the stimulation (prejunctional) experiment. In conclusion, the N-type channel blocking properties and thus sympatholytic effect of cilnidipine could be demonstrated in some (vascular) but not all (cardiac) models studied. At the level of the vasculature cilnidipine reduced the neurotransmitter release to electrical stimulation in both the noradrenaline spillover model and in the model of the rat isolated tail artery, respectively. For amlodipine and nifedipine no sympatholytic activity could be demonstrated. In the pithed rat model, we were unable to demonstrate a selective N-type blocking effect for the VDCC-antagonists.