Real-time measurement of the uncertain epidemiological appearances of COVID-19 infections

Virus diseases are a continued threat to human health in both community and healthcare settings. The current virus disease COVID-19 outbreak raises an unparalleled public health issue for the world at large. Wuhan is the city in China from where this virus came first and, after some time the whole world was affected by this severe disease. It is a challenge for every country's people and higher authorities to fight with this battle due to the insufficient number of resources. On-going assessment of the epidemiological features and future impacts of the COVID-19 disease is required to stay up-to-date of any changes to its spread dynamics and foresee needed resources and consequences in different aspects as social or economic ones. This paper proposes a prediction model of confirmed and death cases of COVID-19. The model is based on a deep learning algorithm with two long short-term memory (LSTM) layers. We consider the available infection cases of COVID-19 in India from January 22, 2020, till October 9, 2020, and parameterize the model. The proposed model is an inference to obtain predicted coronavirus cases and deaths for the next 30 days, taking the data of the previous 260 days of duration of the pandemic. The proposed deep learning model has been compared with other popular prediction methods (Support Vector Machine, Decision Tree and Random Forest) showing a lower normalized RMSE. This work also compares COVID-19 with other previous diseases (SARS, MERS, h1n1, Ebola, and 2019-nCoV). Based on the mortality rate and virus spread, this study concludes that the novel coronavirus (COVID-19) is more dangerous than other diseases.

A Review on Intrusion Detection Systems and Techniques

An Intrusion Detection System (IDS) is a network security system that detects, identifies, and tracks an intruder or an invader in a network. As the usage of the internet is growing every day in our society, the IDS is becoming an essential part of the network security system. Therefore, the proper research and implementation of IDSs are required. Today, with the help of improved technologies at our disposal, many solutions have been found to create many intrusion detection systems. However, it is difficult to identify the perfect solution from the vast options we have available. Hence, motivated by the need of a better security system, this paper presents a survey of different published solutions that have been developed and/or researched on the topic of intrusion detection techniques during the period from 2000 to 2019, including the accuracy of the output. With the help of this survey, an all-inclusive view of the different papers would be at one’s disposal.

IMAGINE Network's Mind And Gut Interactions Cohort (MAGIC) Study: a protocol for a prospective observational multicentre cohort study in inflammatory bowel disease and irritable bowel syndrome

INTRODUCTION

Gut microbiome and diet may be important in irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and comorbid psychiatric conditions, but the mechanisms are unclear. We will create a large cohort of patients with IBS, IBD and healthy controls, and follow them over time, collecting dietary and mental health information and biological samples, to assess their gastrointestinal (GI) and psychological symptoms in association with their diet, gut microbiome and metabolome.

METHODS AND ANALYSIS

This 5-year observational prospective cohort study is recruiting 8000 participants from 15 Canadian centres. Persons with IBS who are 13 years of age and older or IBD ≥5 years will be recruited. Healthy controls will be recruited from the general public and from friends or relatives of those with IBD or IBS who do not have GI symptoms. Participants answer surveys and provide blood, urine and stool samples annually. Surveys assess disease activity, quality of life, physical pain, lifestyle factors, psychological status and diet. The main outcomes evaluated will be the association between the diet, inflammatory, genetic, microbiome and metabolomic profiles in those with IBD and IBS compared with healthy controls using multivariate logistic regression. We will also compare these profiles in those with active versus quiescent disease and those with and without psychological comorbidity.

ETHICS AND DISSEMINATION

Approval has been obtained from the institutional review boards of all centres taking part in the study. We will develop evidence-based knowledge translation initiatives for patients, clinicians and policymakers to disseminate results to relevant stakeholders.Trial registration number: NCT03131414.

[Not Available]

Objectif

Décrire les enjeux cliniques liés à la santé des os chez les patients atteints de la maladie cœliaque (MC) et orienter la surveillance de la santé des os chez ces patients.

Sources d’information

Une recherche a été effectuée sur PubMed dans le but d’examiner les publications appropriées à la MC et la santé des os, y compris les lignes directrices publiées par des organisations professionnelles de gastro-entérologie.

Message principal

Le processus inflammatoire et la malabsorption du calcium et de la vitamine D compromettent la santé des os chez les adultes et les enfants atteints de la MC. La masse osseuse est réduite chez la plupart des adultes dont la MC est symptomatique au diagnostic. Il faut mesurer la densité minérale osseuse au diagnostic et au suivi, surtout chez les adultes. Il faut mesurer le taux de vitamine D au diagnostic et tous les ans, jusqu’à ce qu’il soit normal. Outre un régime strict sans gluten, il faut assurer la supplémentation en calcium et en vitamine D, et encourager les exercices contre résistance.

Conclusion

La santé des os peut être compromise chez les patients atteints de la MC. Ces patients ont besoin d’une supplémentation adéquate en calcium et en vitamine D, de même que de la surveillance du taux de vitamine D et de la densité minérale osseuse lors des suivis réguliers afin de prévenir l’ostéoporose et les fractures.

Management of bone health in patients with celiac disease: Practical guide for clinicians

OBJECTIVE

To describe clinical issues related to bone health in patients with celiac disease (CD) and to provide guidance on monitoring bone health in these patients.

SOURCES OF INFORMATION

A PubMed search was conducted to review literature relevant to CD and bone health, including guidelines published by professional gastroenterological organizations.

MAIN MESSAGE

Bone health can be negatively affected in both adults and children with CD owing to the inflammatory process and malabsorption of calcium and vitamin D. Most adults with symptomatic CD at diagnosis have low bone mass. Bone mineral density should be tested at diagnosis and at follow-up, especially in adult patients. Vitamin D levels should be measured at diagnosis and annually until they are normal. In addition to a strict gluten-free diet, supplementation with calcium and vitamin D should be provided and weight-bearing exercises encouraged.

CONCLUSION

Bone health can be adversely affected in patients with CD. These patients require adequate calcium and vitamin D supplementation, as well as monitoring of vitamin D levels and bone mineral density with regular follow-up to help prevent osteoporosis and fractures.

Effects of competitive learning tools on medical students: A case study

Objective

Competitive learning techniques are being successfully used in courses of different disciplines. However, there is still a significant gap in analyzing their effects in medical students competing individually. The authors conducted this study to assess the effectiveness of the use of a competitive learning tool on the academic achievement and satisfaction of medical students.

Methods

The authors collected data from a Human Immunology course in medical students (n = 285) and conducted a nonrandomized (quasi-experimental) control group pretest-posttest design. They used the Mann-Whitney U-test to measure the strength of the association between two variables and to compare the two student groups.

Results

The improvement and academic outcomes of the experimental group students were significantly higher than those of the control group students. The students using the competitive learning tool had better academic performance, and they were satisfied with this type of learning. The study, however, had some limitations. The authors did not make a random assignment to the control and experimental groups and the groups were not completely homogenous.

Conclusion

The use of competitive learning techniques motivates medical students, improves their academic outcomes and may foster the cooperation among students and provide a pleasant classroom environment. The authors are planning further studies with a more complete evaluation of cognitive learning styles or incorporating chronometry as well as team-competition.

Autotomy prevention by amitriptyline after peripheral nerve section in different strains of mice

This study evaluates the degree of autotomy induced by anesthesia dolorosa after transection of the sciatic and saphenous nerves in four different strains of mice, and the effectiveness of amitriptyline administration in two of them. The self-mutilating lesions were assessed by means of an autotomy score for one month after denervation. The onset of lesions generally occurred during the first week, starting in the nails and progressing proximally. Autotomy behavior developed differently in the mouse strains studied, involving 88% of the paw areas in OF1 mice, 61% in Balb-C, 35% in NMRI, and 15% in B6CBAF1. Two selected strains, OF1 and NMRI, were treated with amitriptyline (8 mg/kg/day, p.o.) from different intervals pre-operation. Administration starting 14 days before nerve lesion was the most effective treatment schedule for reducing autotomy in both strains.

Role of metallothioneins in peripheral nerve function and regeneration

The physiological role of the metallothionein (MT) family of proteins during peripheral nerve injury and regeneration was examined in Mt1+ 2 and Mt3 knockout (KO) mice. To this end, the right sciatic nerve was crushed, and the regeneration distance was evaluated by the pinch test 2-7 days postlesion (dpl) and electrophysiologically at 14 dpl. The quality of the regeneration was assessed by light microscopy and immunohistochemical methods. The results show that the regeneration distance was greater in the Mt3 KO than in the Mt1+ 2 KO mice, whereas control mice showed intermediate values. Moreover, the number of regenerating axons in the distal tibial nerve was significantly higher in Mt3KO mice than in the other two strains at 14 dpl. Immunoreactive profiles to protein gene product 9.5 were present in the epidermis and the sweat glands of the plantar skin of the hindpaw of the Mt3 KO group. The improved regeneration observed with the Mt3 KO mice was confirmed by compound nerve action potentials that were recorded from digital nerves at 14 dpl only in this group. We conclude that Mt3 normally inhibits peripheral nerve regeneration.

Engineering an artificial nerve graft for the repair of severe nerve injuries

Nerve repair with tubes has a limit to regeneration depending upon the length of the gap. The characteristics of the guide, in terms of permeability, durability and adhesiveness, also influence regeneration. Considering the importance of the cellular component in regeneration, the development of artificial grafts, composed of a biocompatible nerve guide filled with a neurotropic matrix and seeded with Schwann cells (SCs), is an interesting option to enhance nerve regeneration and provide an alternative to the classical autologous nerve graft. We evaluated the ability of SCs transplanted into a nerve guide to improve regeneration after sciatic nerve resection, leaving a 6-mm gap, in the mouse. Syngeneic, isogeneic and autologous SCs were suspended in Matrigel and seeded in resorbable guides, and compared to acellular guides and to nerve autografts. The immunogenicity of the transplanted SCs clearly influenced the outcome. Transplants of autologous SCs resulted in only slightly lower levels of reinnervation than autografts, but higher recovery and number of regenerated axons than transplants of isologous and syngeneic SCs, and than acellular guides. Thus, by combined developments on nerve guides, extracellular matrix components and cell transplantation, an artificial graft has been designed that allows axonal regeneration across long gaps to levels comparable with an autograft.

Effects of ensheathing cells transplanted into photochemically damaged spinal cord

Transplantation of olfactory ensheathing cells (OECs) into photochemically damaged rat spinal cord diminished astrocyte reactivity and parenchyma cavitation. The photochemical lesion performed at T12--L1 resulted in severe damage to the spinal cord, so that during the first 15 days postoperation all rats dragged their hindlimbs and did not respond to pinprick. The maximal area and volume of the cystic cavities were lower in transplanted than in non-transplanted rats, not significantly at the T12--L1 lesion site, but significantly at T9--T10 and L4--L6 cord levels. The density of astrocytes in the grey matter was similar at T12--L1 and L4--L6 in non-transplanted and trans- planted rats, but lower in the latter at T9--T10 level. However, in non-transplanted rats all astrocytes showed a hypertrophied appearance, with long and robust processes heavily GFAP-positive, and overexpression of proteoglycan inhibitor of neuritogenesis, whereas in transplanted rats only a few astrocytes showed hypertrophy and the majority had short, thin processes. These results indicate that OECs transplanted into damaged adult rat spinal cord exert a neuroprotective role by reducing astrocytic gliosis and cystic cavitation.

Molecular and conventional epidemiology of tuberculosis in an inner city district

SETTING

Molecular epidemiology has underlined the importance of recent tuberculosis (TB) transmission and has uncovered notable discrepancies compared with conventional epidemiology.

OBJECTIVES

1) To determine, by RFLP analysis, the percentage of clustered cases in an inner city district with a high incidence of TB (163/100,000) and the groups at risk of being clustered; and 2) to compare the role of conventional contact tracing (CCT) with that of RFLP.

DESIGN

RFLP was carried out using the IS6110 and pTBN12 (PGRS) sequences of 165 cultures positive for Mycobacterium tuberculosis in the Ciutat Vella district of Barcelona during 1997-1998. Contact tracing was carried out in 171 of 251 declared cases (68.1%). Associations were assessed by calculating odds ratios (OR) with 95% confidence intervals (CI). Logistic regression was used for multivariate analysis.

RESULTS

Using RFLP, 76 (46.0%) strains were found to be clustered by IS6110 and PGRS. From CCT, 30 new patients were found among 858 contacts (3.5%) and 57 patients were linked. In terms of RFLP and CCT, the main risk factor was intravenous drug use (IVDU). In 44 cases who lived alone and were not involved in CCT, 50% were in RFLP clusters. The concordance rate between RFLP and CCT was 8/13 (61.5%); the disagreement corresponded to a cluster of five recent immigrants from Africa. Subsequent to RFLP, an epidemiological connection was found in 15/55 cases (27.2%).

CONCLUSIONS

The percentage of clustered cases is very high. CCT was useful for identifying new cases, but it was insufficient for detecting the pathways of transmission. CCT coverage needs to be improved in marginalized individuals, and the results correlated with those of RFLP.

Influence of aging on peripheral nerve function and regeneration

Aging deeply influences several morphologic and functional features of the peripheral nervous system (PNS). Morphologic studies have reported a loss of myelinated and unmyelinated nerve fibers in elderly subjects, and several abnormalities involving myelinated fibers, such as demyelination, remyelination and myelin balloon figures. The deterioration of myelin sheaths during aging may be due to a decrease in the expression of the major myelin proteins (P0, PMP22, MBP). Axonal atrophy, frequently seen in aged nerves, may be explained by a reduction in the expression and axonal transport of cytoskeletal proteins in the peripheral nerve. Aging also affects functional and electrophysiologic properties of the PNS, including a decline in nerve conduction velocity, muscle strength, sensory discrimination, autonomic responses, and endoneurial blood flow. The age-related decline in nerve regeneration after injury may be attributed to changes in neuronal, axonal, Schwann cell and macrophage responses. After injury, Wallerian degeneration is delayed in aged animals, with myelin remnants accumulated in the macrophages being larger than in young animals. The interaction between Schwann cells and regenerative axons takes longer, and the amount of trophic and tropic factors secreted by reactive Schwann cells and target organs are lower in older subjects than they are in younger subjects. The rate of axonal regeneration becomes slower and the density of regenerating axons decrease in aged animals. Aging also determines a reduction in terminal and collateral sprouting of regenerated fibers, further limiting the capabilities for target reinnervation and functional restitution. These age-related changes are not linearly progressive with age; the capabilities for axonal regeneration and reinnervation are maintained throughout life, but tend to be delayed and less effective with aging.

Expansion of adult Schwann cells from mouse predegenerated peripheral nerves

We present an effective technique for culture and expansion of Schwann cells (SC) from adult peripheral nerves. Cultures from adult mouse sciatic nerves (one to six nerves per culture) in defined medium showed markedly higher purity and density of SC when the nerve was predegenerated in vivo for 7 days than when it was harvested fresh. SC from degenerated nerves were then cultured in defined media conditioned by primary cultures of adult SC. The best results were obtained with a conditioned medium supplemented with 1% fetal calf serum. In these conditions the purity of SC was about 90% and the density about 190 cell/mm(2) by 7-10 days in vitro. These findings indicate that adult SC can be expanded from small preinjured nerve fragments in a short time period to provide a source of SC for autologous cellular transplants.

Nerve guides seeded with autologous schwann cells improve nerve regeneration

This study evaluates the ability of Schwann cells (SCs) transplanted into a nerve guide to improve regeneration and reinnervation after sciatic nerve resection and repair, leaving a 6-mm gap, in the mouse. SCs were isolated from predegenerated adult sciatic nerves and expanded in culture using a chemically defined medium. Syngeneic, isogeneic, and autologous SCs were suspended in Matrigel and seeded in resorbable, permeable poly(l-lactide-co-epsilon-caprolactone) guides at 150,000 cells/tube. Guides containing SCs were compared to guides filled with Matrigel alone and with peroneal nerve autografts. Functional reinnervation was assessed by noninvasive methods to determine recovery of sweating, nociceptive, sensory, and motor functions in the hindpaw during 4 months postoperation. Morphological analysis of the regenerated nerves was performed at the end of follow-up. The group with an autograft achieved faster and higher levels of reinnervation and higher number of regenerated myelinated fibers than groups repaired by tubulization. The immunogenicity of transplanted SCs influenced the outcome of nerve regeneration. Transplants of autologous SCs resulted in slightly lower levels of reinnervation than autografts, but higher recovery and number of regenerated fibers reaching the distal nerve than transplants of isologous and syngeneic SCs, although most of the differences were not statistically significant. Syngeneic SCs did not improve regeneration with respect to acellular guides. Prelabeled transplanted SCs were found to survive into the guide 1-3 months after implantation, to a larger number when they were autologous than syngeneic. Cellular prostheses composed of a resorbable guide seeded with autologous SCs appear as an alternative for repairing long gaps in injured nerves, approaching the success of autografts.

Morphometric and ultrastructural changes with ageing in mouse peripheral nerve

Qualitative and quantitative information is reported on the morphological changes that occur in nerve fibres and nonneuronal cells of peripheral nerve during the lifetime of the mouse. Tibial nerves of mice aged 6-33 mo were studied. With ageing, collagen accumulates in the perineurium and lipid droplets in the perineurial cells. Macrophages and mast cells increase in number, and onion bulbs and collagen pockets are frequently present. Schwann cells associated with myelinated fibres (MF) slightly decrease in number in parallel with an increase of the internodal length from 6 to 12 mo, but increase in older nerves when demyelination and remyelination are common. The unmyelinated axon to myelinated fibre (UA/MF) ratio was about 2 until 12 mo, decreasing to 1.6 by 27 mo. In older mice, the loss of nerve fibres involves UA (50% loss of 27-33 mo cf. 6 mo) more markedly than MF (35%). In aged nerves wide incisures and infolded or outfolded myelin loops are frequent, resulting in an increased irregularity in the morphology of fibres along the internodes. In the mouse there is an adult time period, 12-20 mo, during which several features of degeneration progressively appear, and an ageing period from 20 mo upwards when the nerve suffers a general disorganisation and marked fibre loss.

Early social isolation decreases the expression of calbindin D-28k in rat cerebellar Purkinje cells

The main objective of this study was to analyze the effects of early social isolation on the expression of calbindin D-28k (CAD-28k) in cerebellar Purkinje cells. Sprague-Dawley rats were reared either in isolation (IC) or socially housed conditions (SC) from postnatal days 18-32. Half of the rats of each group were sacrificed at 32 days of age and the cerebella processed for immunocytochemical labeling against CAD-28k. The remaining IC animals were housed under standard conditions for re-socialization between postnatal days 32 and 62. The results indicate that Purkinje cells of rats reared under early isolation show a marked loss of CAD-28k immunoreactivity, and that this deficiency is recovered by later social interaction, although the thickness of the molecular layer remains reduced.

Prolongation of nerve and epidural anesthetic blockade by bupivacaine in a lipid emulsion

We assessed the effect of a lipid emulsion of bupivacaine on prolonging peripheral nerve and epidural anesthetic blockade in the rat. The intensity and duration of motor and sensory blockade produced by a single injection of aqueous solution (BPV-as) and lipid emulsion (BPV-em) preparations of 0.5% bupivacaine were evaluated by electrophysiological methods. Both preparations induced complete, reversible motor and sensory blockade after injection. The latency time to the maximal blockade and the duration of anesthetic blockade were more prolonged for BPV-em than for BPV-as. The increase in duration of maximal blockade was 1.4 times for nerve and 1.3 times for epidural anesthesia. Histological evaluation of spinal roots and spinal cord sections did not show any abnormalities or differences between animals injected with BPV-as and those injected with BPV-em. Pharmacokinetic studies showed lower plasma peak concentration and a longer elimination half-life for BPV-em than for BPV-as. Thus, BPV-em prolongs the effects of local anesthetics, allows a similar degree of blockade, and reduces the systems toxic effects of anesthetics compared with BPV-as.

IMPLICATIONS

We assessed a lipid emulsion containing bupivacaine for peripheral nerve and epidural anesthetic blockade in the rat. The emulsion allowed a complete blockade, while increasing the duration of the anesthetic effect (by 30%-40%), compared with the standard bupivacaine aqueous solution.

Olfactory bulb ensheathing cells enhance peripheral nerve regeneration

Sciatic nerve resection leaving a 15 mm gap could not be repaired by bridging the stumps with a silicone tube prefilled with a laminin gel. However, when purified olfactory ensheathing cells (EC) were added to the gel filling the tube, successful axonal regeneration was observed in 50% of rats. With 12 mm gaps, regeneration occurred in 79% of rats with transplanted EC compared with 60% of those receiving collagen gel alone. Therefore, ECs help repair severe peripheral nerve injuries, in addition to their ability to promote axonal regeneration within the central nervous system.

Physiological and immunohistochemical characterization of cisplatin-induced neuropathy in mice

We investigated the neuropathic effects of cisplatin in two groups of mice treated with 5 or 10 mg/kg/week of cisplatin for 7 or 8 weeks. Peripheral nerve functions were evaluated by sweat imprints, and electrophysiological, rotarod, and nociceptive tests. Protein gene product 9.5 (PGP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP) were immunohistochemically localized in footpads. Tibial nerves were analyzed morphometrically. Functional deficits developed progressively with higher cumulative doses, more markedly in mice treated with high than in those with low doses. From cumulative doses of 10 mg/kg, significant declines in sensory nerve conduction velocity and sudomotor responses were found, whereas motor and nociceptive functions were involved later. There were no morphometrical changes in tibial nerves. A marked decrease of CGRP- and VIP-immunoreactive nerves occurred in samples from treated mice, whereas PGP-labeled profiles decreased mildly at late stages. Impairment of the content of neuropeptides with neurosecretor role was detectable earlier than functional abnormalities. Immunohistochemical analysis of skin biopsies offers a useful diagnostic tool for peripheral neuropathies.

Ensheathing glia transplants promote dorsal root regeneration and spinal reflex restitution after multiple lumbar rhizotomy

Previously, we have shown that transplants of olfactory bulb ensheathing cells promoted regeneration of transected dorsal roots into the spinal cord. In this study, we assessed the ability of regenerating axons to make functional connections in the cord. Dorsal roots L3 to L6 were sectioned close to their entrance into the spinal cord and reapposed after injecting a suspension of ensheathing cells into each dorsal root entry zone (Group G). Afferent regeneration into the cord and recovery of spinal reflexes were compared with animals that received no injection (Group S) or culture medium without cells (Group C). Electrophysiological tests, to measure nerve conduction and spinal reflexes (H response and withdrawal reflex) evoked by stimulation of afferents of the sciatic nerve, were performed. At 14 days after surgery, H response was found in only 1 of 7 rats of Group G, and withdrawal reflexes were absent from all animals. At 60 days, the H response reappeared in 7 of 10 rats of Group G, and 1 of 5 of each of Groups C and S. The withdrawal reflex recovered in 4 of 10 rats of Group G, but in none of Groups C and S. Immunohistochemical labeling for calcitonin gene-related peptide (CGRP) in rats of Group G showed immunoreactive fibers entering the dorsal horn from sectioned roots, although at lower density than in the contralateral side. In conclusion, transplanted ensheathing cells promoted central regeneration and functional reconnection of regenerating sensory afferents.

Changes in cholinergic responses of sweat glands during denervation and reinnervation

Functional sudomotor responses have been studied in sweat glands reinnervated after sciatic nerve crush and partially denervated by cisplatin intoxication in the mouse. The sudomotor function mediated by the sciatic nerve was evaluated by silicone imprints on the plantar surface of the hindpaws. Five days after nerve crush, completely denervated sweat glands became unresponsive to cholinergic stimulation with pilocarpine. During the following weeks, the number of reinnervated, reactive sweat glands increased progressively to reach a maximum of 89% of preoperative control counts by 40 days after nerve crush. At this time, the mean volume of sweat secreted per gland was normal, but reinnervated glands showed a secretory activity abnormally sustained over time after pilocarpine stimulation and, on the other hand, had an increased resistance to the inhibition of secretion induced by atropine. The effects of cisplatin administration on sudomotor function were investigated in two groups of mice, one treated with high doses of cisplatin (10 mg/kg/week for 4 weeks) and another treated with low doses of cisplatin (5 mg/kg/week for 8 weeks). Cisplatin intoxication produced abnormal sudomotor responses indicative of denervation from cumulative doses of 10 mg/kg. The first abnormality found was a partial resistance of sweat glands to atropine, followed by a decrease in the sweat output per gland and finally a decline in the number of sweat glands activated by pilocarpine. These abnormalities in the sudomotor responses were more pronounced in mice treated with a high dose than in those with a lower dose regime.

Effect of curing Helicobacter pylori infection on intragastric acidity during treatment with ranitidine in patients with duodenal ulcer

BACKGROUND

In patients with duodenal ulcer cure of Helicobacter pylori infection resulted in a pronounced decrease in intragastric pH during treatment with omeprazole.

AIM

To test the hypothesis that treatment of H pylori adversely affects the pH response to ranitidine.

PATIENTS

Eighteen patients with duodenal ulcer who were infected with H pylori were studied.

METHODS

Twenty four hour pH recordings were performed during treatment with ranitidine (300 mg) at night before and four to six weeks after cure of H pylori infection. Presence of H pylori was assessed by a rapid urease test, culture, histology, and a 13C urea breath test. Also, the fasting gastrin concentrations were measured before and after treatment for H pylori infection.

RESULTS

Cure of H pylori infection resulted in a considerable improvement in both antral and corpus gastritis and a decrease in fasting gastrin concentrations. As a result of the cure the night time intragastric pH during treatment with ranitidine decreased (median pH 6.8 v 5.4; p = 0.007), whereas the acidity during the daytime was not affected.

CONCLUSIONS

In patients with duodenal ulcer the intragastric pH during treatment with ranitidine depends on H pylori. However, the loss of effectiveness in altering pH seems to be less pronounced than previously found with omeprazole.

Immunohistochemical study of skin reinnervation by regenerative axons

The time sequence of sensory and sudomotor nerve regeneration to the mouse footpad was studied between one and seven weeks after crush or section of the sciatic nerve. Protein gene product 9.5, vasoactive intestinal peptide, substance P, and calcitonin gene-related peptide were localized in thick sections by using indirect immunofluorescence techniques and imaged by confocal microscopy. Nerve regeneration was visually assessed in all nerves and quantified in sweat glands. After denervation, protein gene product 9.5 immunoreactivity remained as dim fluorescence within thick fibers of dermal nerve trunks, whereas thin nerve fibers to sweat glands and to epidermis disappeared. By 14 days postcrush and 35 days postsection, the first protein gene product 9.5 immunoreactive regenerating axons appeared in large nerve trunks, quickly extending to epidermis and sweat glands. Reinnervation of Meissner's corpuscles occurred nearly simultaneous with return of epidermal free nerve endings and sudomotor network. Calcitonin gene-related peptide, vasoactive intestinal peptide, and substance P immunoreactivity disappeared completely one week after denervation, then reappeared at 17-18 days postcrush and 35 days postsection. Fewer nerve fibers were immunoreactive to these peptides than to protein gene product 9.5. The overall density of reinnervation, although reduced, more closely resembled normal in the sweat glands and Meissner's corpuscles than in the epidermis. Reinnervation was more successful after crush than after nerve section. The time course for functional return of sweating paralleled the return of protein gene product 9.5 immunoreactivity, whereas appearance of vasoactive intestinal peptide was delayed by several days.

Efficacy of omeprazole one year after cure of Helicobacter pylori infection in duodenal ulcer patients

OBJECTIVE

We have previously shown that, in duodenal ulcer patients, pH control by omeprazole is less pronounced after cure of Helicobacter pylori infection. The present study was designed to test the hypothesis that this response to omeprazole persists 1 yr after cure of H. pylori infection.

METHODS

In 12 duodenal ulcer patients, intragastric acidity was measured with a glass electrode during treatment with omeprazole (20 mg) once daily before, and 4-6 wk and 1 yr after, cure of H. pylori infection. H. pylori infection was assessed by [13C]urea breath test, culture, histology (Warthin Starry stain), and rapid urease test.

RESULTS

Cure of H. pylori infection resulted in a lowered pH during omeprazole treatment. This effect persisted after 1 yr. Median 24-h gastric pH before H. pylori treatment was 5.6; 4-6 wk after cure of the infection it was 2.9 (p = 0.003), and 1 yr after cure of the infection it remained unchanged (pH = 2.5; p = 0.5). Accordingly, twice as much time was spent above pH 3 and pH 4 before H. pylori treatment than 1 or 12 months after cure (percent of time > or = pH 3: 82.7 vs. 49.7 vs. 43.1; percent of time > or = pH 4: 72.7 vs. 38.3 vs. 26.4).

CONCLUSION

In duodenal ulcer patients, cure of H. pylori infection resulted in a marked rapid and persistent decrease of the pH increasing effect of omeprazole. Therefore, H. pylori is a determinant of the pH achieved in response to omeprazole treatment in duodenal ulcer patients.

Influence of physical parameters of nerve chambers on peripheral nerve regeneration and reinnervation

We compared reinnervation of target organs after sciatic nerve section leaving gaps of 2, 4, 6, or 8 mm or gaps repaired with silicone tubes in different groups of mice. Functional reinnervation was assessed by noninvasive methods to determine recovery of sweating, nociceptive, and muscular functions in the hindpaw repeatedly during 3 months postoperation. The increase of gap length between nerve stumps delayed the beginning and reduced the degree of functional recovery achieved either with or without repair. When lesions were left unrepaired, functional reinnervation was only noticeable with a 2-mm gap and practically absent with longer gaps. With tube repair, reinnervation started earlier and achieved higher values than in the corresponding unrepaired groups. Tubulization was most effective with 4-mm gaps and comparatively less with shorter and longer gaps. With 4-mm gaps, recovery was higher when the silicone tube had a cross-sectional area 2.5 times that of the sciatic nerve than with narrower or wider tubes and when the wall was the thinnest available. In all cases muscle reinnervation showed a lower progression than sweating and nociceptive recovery.

Functional changes of the peripheral nervous system with aging in the mouse

The influence of aging on peripheral nerve and target organ function was investigated in six groups of mice aged 2, 6, 9, 12, 18, and 24 months. Sudomotor, motor, and sensory functions mediated by the sciatic nerve were evaluated by silicone imprints, electrophysiological recordings and pinprick test from the distal hindpaw. Nerve conduction was also studied in the caudal nerves. The results showed that the number of sweat glands reactive to pilocarpine does not change significantly with aging, but the size of the sweat droplets is smaller in aged mice than in young mice. The amplitude of muscle and nerve action potentials evoked by stimulation of sciatic and caudal nerves decreased progressively from 2 to 24 months, while the latencies decreased from 2 to 6 months, remained unchanged until 12 months and increased thereafter. All the animals of the six groups studied showed positive, indistinguishable responses to pinprick. These results indicate that neurophysiological responses mediated by large diameter nerve fibers deteriorated with age, while those dependent of small fibers were preserved.

The effect of aging on efferent nerve fibers regeneration in mice

This study evaluates the influence of aging on nerve regeneration and reinnervation of target organs in mice aged 2, 6, 9, 12, 18 and 24 months. In animals of each age group the sciatic nerve was subjected to crush, section or section and suture. Reinnervation of plantar muscles and sweat glands (SG) was evaluated over three months after operation by functional methods. Reappearance of SG secretion and motor responses occurred slightly earlier in young than older mice. The degree of motor and sudomotor reinnervation, with respect to preoperative control values, was also significantly higher in young than old animals. The differences were more pronounced after 12 months of age. The degree of recovery progressively decreased with the severity of the lesion, differences being more marked in older mice. Neurorraphy improved recovery, comparatively more in older than in young mice. These results indicate that, after injuries of peripheral nerves, axonal regeneration and reinnervation are maintained throughout life, but tend to be more delayed and slightly less effective with aging.

Functional sudomotor responses to cholinergic agonists and antagonists in the mouse

This study evaluates the functional activity of the mouse sweat glands in response to cholinergic agonists and antagonists using the silicone imprint technique. In intact mice the response to acetylcholine, methacholine and pilocarpine did not differ significantly from control saline injection, indicating that immobilization induces high levels of sweating, masking the effects of cholinergic stimulation. Plantar emotional sweating was completely abolished by local anesthesia at the ankle. Under these conditions, administration of acetylcholine only provoked detectable sweating when injected locally into the sole skin. Methacholine activated an increasing number of sweat glands in a dose-dependent manner between 0.5 and 10 mg/kg; the response was maximal after 5-10 min of administration and decreased subsequently. With pilocarpine the maximum number of reactive sweat glands was observed at a dose of 2.5 mg/kg. The response was stable for 45 min with doses 2.5 and 5 mg/kg, but decreased exponentially with higher doses. The subtype of sweat gland muscarinic receptor was characterized by determining the inhibitory effect of different cholinergic antagonists on pilocarpine response. Atropine and 4-DAMP were equally potent inhibitors, showing a dose-related effect from 0.05 mg/kg. Pirenzepine only showed inhibitory effects with doses 10-times higher, whereas gallamine and hexamethonium did not induce inhibition at any of the doses tested. These findings suggest that the mouse eccrine sweat gland muscarinic receptors are predominantly M3.

Innervation of cutaneous structures in the mouse hind paw: a confocal microscopy immunohistochemical study

The normal innervation of structures in mouse foot pads was investigated with immunohistochemistry and confocal microscopy. Nerves were visualized by incubating Zamboni fixed, thick, frozen sections with antibodies to protein gene product 9.5 (PGP 9.5), vasoactive intestinal peptide, substance P, calcitonin gene-related peptide, and protein zero. The antibodies were localized using cyanine 3.18 labeled anti-rabbit gamma globulin. PGP 9.5 immunolocalization showed dense nerve bundles at the base of the foot pad with branches to larger blood vessels, sweat glands and epidermis. Sweat gland tubules were surrounded by numerous sudomotor axons; single fibers accompanied the sweat duct toward the skin's surface. Nerve bundles containing myelinated and unmyelinated axons ran through and around the centrally located sweat gland cluster to end in free nerve endings and Meissner's-like corpuscles at the apex of the foot pad. Other bundles running parallel to the epidermis gave arcuate branches that supplied epidermis on the sides of the pads with a rich nerve network, principally with free nerve endings that often reached the most superficial cell layers of epidermis. Calcitonin gene-related peptide-immunoreactive (-ir) nerves were distributed to dermis and epidermis in lower density than PGP 9.5-ir fibers. Substance P-ir fibers were less numerous; most terminated as free endings in deeper layers of epidermis. Vasoactive intestinal peptide-ir nerves almost exclusively innervated sweat glands, ducts and blood vessels, but not epidermis. The mouse hind paw has potential to serve as a model system for investigations of functional and morphological changes that affect peripheral and autonomic nerves under diverse experimental conditions.

[Methodological considerations concerning peripheral nerve morphometry]

Morphometric studies of the peripheral nerve often present widely varying results which, in part at least, may be attributed to the different methodologies used. Two questions may be of importance with regard to the reliability of such results: the preselection of fibres according to their morphology and the method used in quantifying observations. In this work a morphological study was carried out on the myelinated fibres of the sciatic nerve of a rat in order to evaluate fibre selection criteria. A morphometric analysis was also performed using manual measurements, image digitalisation and surveying, and automatic image analysis. It was shown that morphological variability of transverse section fibres is considerable and that, really, the proportion of circular fibres with homogeneous compact myelin is only 50 to 70%, from which we can conclude that the selection of fibres carried out in some studies wishing to eliminate abnormal fibres is somewhat exaggerated. By analysing the fibres using various methods significant differences appear, some due to the fact that distinct methods may be used to calculate the same parameters in a different way. The most reliable parameters would appear to be those which do not depend on the shape of the fibres and those which automatic or semiautomatic methods can calculate directly such as areas and perimeters. In any case quantifying methods seem hardly discriminatory and the differences between methods disappear if analyses are carried out using random samples. Preselection of fibres appears unnecessary in this context as in no case are the results altered. Finally we suggest finishing quantitative analyses with qualitative studies which would permit getting more information especially useful in cases of ageing, regeneration or pathological studies.

[Degeneration and regeneration of the peripheral nervous system with aging]

Clinical and experimental studies have shown that with aging there appear neurological changes which affect both the Central Nervous System (CNS) as well as the Peripheral Nervous System (PNS), bringing about a series of cognitive, sensory and physical disabilities in older people. Nerve lesions also cause disability. The basic mechanisms which begin with lesioned neurons have proved an interesting field of study for many neuroscientists since as far back as the mid-nineteenth century. However the influence of age on these postlesion neuronal processes has not aroused the same level of interest even though many authors have, out of curiosity, published reports of changes which take place in regenerative neurons as a result of age. The progressive increase in the aged population in industrialised nations warrants a detailed study into the influence of age on such neuronal processes. The PNS, due to its accessibility and greater regenerative potential vis-à-vis the CNS, may be a good model for this purpose. From results obtained by both other authors and ourselves it is clear that aging causes a decline in the regenerative abilities of peripheral nerve fibres. Functional recovery is not only slowed down but also decreases with age. The number of regenerative axons and their capacity for end sprouting, together with the biosynthesis and transport of new materials in the regenerative neurons, as well as the proliferation and synthesis of trophic factors by Schwann cells also decay. All of this leads to the fact that the regenerative capacity of nerve fibres is lesser with age, and that functional disabilities after a lesion are greater in older than in younger people.

Comparison of regenerative and reinnervating capabilities of different functional types of nerve fibers

Functional reinnervation of sweat glands (SGs), skin, and muscle in the mouse paw after sciatic nerve lesions was evaluated to allow comparisons of the regeneration efficiency of different functional types of nerve fibers. In four groups of mice the sciatic nerve was crushed, sectioned, and left unrepaired or repaired by suture or tubulization. Reappearance of SG secretion and pinprick responses occurred slightly earlier than recordings of compound muscle and nerve action potentials in all groups. The degree of reinnervation, with respect to preoperative control values, of SGs and skin nociceptors was higher than the amplitude of the action potentials, mainly when the nerve injury was severe. The chances for recovery progressively decreased with the severity of the lesion, affecting the larger nerve fibers most. These results indicate that, after injuries of peripheral nerves, all types of nerve fibers are able to regenerate in the mouse, although small size fibers (sudomotor and nociceptive) allow for a higher degree of functional recovery than large myelinated fibers (skeletomotor and sensory).

Effects of dizocilpine on autotomy behavior after nerve section in mice

The effects of acute administration of dizocilpine (MK-801) at different perioperative times on autotomy behavior after sciatic and saphenous nerve transection were studied in the mouse. Control mice developed a severe self-mutilating behavior starting 1-3 days postoperation and reaching a maximum by 11 days. Mice injected with a single dose of dizocilpine (0.4 mg/kg i.p.) before operation, the 1st or 3rd postoperative day autotomized significantly less than controls. An 1-wk treatment with the same dose once a day did not show further benefit. A single administration of dizocilpine the 5th day after surgery slightly halted further progression of autotomy. Dizocilpine did not have any deleterious effect on normal peripheral nerve function. These results suggest that NMDA receptor blockade prevents development of hyperalgesia and neuropathic pain after peripheral nerve injuries but only when it is administered before or during the first 3 days after injury.

Abnormalities of sympathetic sudomotor function in experimental acrylamide neuropathy

The possible involvement of sympathetic sudomotor function by acrylamide intoxication was investigated in the mouse, and compared with nerve conduction studies and global motor tests. Acrylamide (40 mg/kg, 3 days per week, 8 weeks) was given per os to a group of mice (A1). Their motor ability to stand on the rotarod was impaired from day 11, reaching a minimum between 46 and 60 days. The number of pilocarpine reactive sweat glands (SG), evaluated by the silicone mold technique, was similar to controls at 40 days and slightly decreased at 54 days. Another group of mice (A2), given acrylamide at a higher dose (50 mg/kg, 5 days per week, 5 weeks), showed abnormalities on the rotarod by 11 days, a progressive decrease of muscle action potential (CMAP) amplitude, and significantly decreased number of reactive SG from 15 days, with respect to controls. Comparatively, sudomotor dysfunction was milder and appeared later in time than alphamotor involvement, being noticeable only after severe poisoning. The decrease in SG response is attributable to damage by acrylamide intoxication of postganglionic sudomotor nerve fibers, which are unmyelinated sympathetic efferents.