Patient-specific rods in adult spinal deformity: a systematic review

PURPOSE

The purpose of this review was to evaluate the effectiveness of patient-specific rods for adult spinal deformity.

METHODS

A systematic review of the literature was performed through an electronic search of the PubMed, Scopus, and Web of Science databases. Human studies between 2012 and 2023 were included. Sample size, sagittal vertical axis (SVA), pelvic incidence-lumbar lordosis (PI-LL), pelvic tilt (PT), operation time, blood loss, follow-up duration, and complications were recorded for each study when available.

RESULTS

Seven studies with a total of 304 adult spinal deformity patients of various etiologies were included. All studies reported SVA, and PT; two studies did not report PI-LL. Four studies reported planned radiographic outcomes. Two found a significant association between preoperative plan and postoperative outcome in all three outcomes. One found a significant association for PI-LL alone. The fourth found no significant associations. SVA improved in six of seven studies, PI-LL improved in all five, and three of seven studies found improved postoperative PT. Significance of these results varied greatly by study.

CONCLUSION

Preliminary evidence suggests potential benefits of PSRs in achieving optimal spino-pelvic parameters in ASD surgery. Nevertheless, conclusions regarding the superiority of PSRs over traditional rods must be judiciously drawn, given the heterogeneity of patients and study methodologies, potential confounding variables, and the absence of robust randomized controlled trials. Future investigations should concentrate on enhancing preoperative planning, standardizing surgical methodologies, isolating specific patient subgroups, and head-to-head comparisons with traditional rods to fully elucidate the impact of PSRs in ASD surgery.

Simple schwannomatosis or an incomplete Coffin-Siris? Report of a particular case

BACKGROUND

Schwannomatosis is a genetic disorder that belongs to NF family. The mutation of SMARCB1 gene has been related to this entity and Coffin-Siris syndrome, as well. We reported a case of a female patient with SMARCB1 mutation who has developed a spontaneuous spleen rupture.

CASE DESCRIPTION

A 28 years old female patient with a story of a Sjogren syndrome, celiac disease and a surgically treated schwannoma, presented to our observation in July 2013 for a pain on the left elbow, where a tumefation was present. After neuroradiological evaluations, a surgical resection was performed and a schwannoma was diagnosed. Genetic exams revealed a puntiform SMARCB1 gene mutation. During 2015, she was subdued to the removal of an another schwannoma located into the cervical medullary canal. Few months later, she was operated in an another hospital for a spontaneous spleen rupture in a possible context of wandering spleen.

CONCLUSION

We think that the patient could suffer from a partially expressed Coffin-Siris syndrome. No cases of spontaneous rupture in a context of wandering spleen have been ever described as for as schwannomatosis or Coffin-Siris syndrome are concerned. More cases are necessary to establish a direct relationship.

The neural correlates of road sign knowledge and route learning in semantic dementia and Alzheimer's disease

BACKGROUND

Although there is a growing body of research on driving and Alzheimer's disease (AD), focal dementias have been understudied. Moreover, driving has never been explored in semantic dementia (SD).

METHODS

An experimental battery exploring road sign knowledge and route learning was applied to patients with SD and AD selected in the early-moderate stage of disease and to a group of healthy participants. Neuropsychological data were correlated to cerebral hypometabolism distribution, investigated by means of positron emission tomography.

RESULTS

The two dementias showed opposite profiles. Patients with SD showed poor road sign knowledge and normal performance in route learning. By contrast, patients with AD showed low performance in route learning test with preservation of semantic knowledge of road signs. In SD, there was a correlation of semantic knowledge impairment with hypometabolism in the left temporolateral cortex. No correlation between the AD region of interests (ROIs) and the relevant behavioural indices was found, while in the whole-brain analysis there was a significant correlation between route learning and the superior frontal gyrus.

DISCUSSION AND CONCLUSIONS

For the first time, driving skills were explored in SD, and it is showed a differential profile from the one detected in AD. We demonstrate that the left anterior temporal cortex is implicated in road sign knowledge, while a distributed cortical network, including the frontal cortex, is likely to process route learning.

Diagnostic delay in migraine with aura

Migraine with aura (MWA) is a common headache, characterized by short-lasting neurological signs preceding an headache attack with migraine characteristics. We have recently performed several investigations about time-delay for migraine without aura diagnosis (MWoA). Aim of this study was to compare the time necessary to obtain a correct diagnosis in MWA and MWoA patients. We enrolled 31 consecutive patients affected by MWA and 62 age- and sex-matched patients affected by MWoA. All subjects were submitted to a face-to-face interview about the time-delay from symptoms' onset and a correct migraine typology diagnosis, the number of specialists consulted and the instrumental examinations performed. Independent samples and repeated measures t test, Mann-Whitney U were performed to compare the variables of the cases with the matched controls. No significant differences were found among the collected variables. Diagnostic delay was significantly different (p < 0.05), resulting lower in patients affected by MWA than in those with MWoA. In fact, subjects affected by MWA had a mean diagnostic delay of 6.70 years (SE ± 1.5), while patients affected by MWoA had a mean interval of 10.7 years (SE ± 1.20). Patients affected by MWA present a significant lower delay for the formulation of a correct diagnosis with respect to subjects with MWoA. This could be probably due to the fact that MWA patients develop major alarm reactions related to visual symptoms and look for an earlier appointment with a specialist medical center.

The real usefulness and indication for migraine diagnosis of neurophysiologic evaluation

According to IHS criteria, a correct clinical history is fully adequate for a diagnosis of migraine. Patients usually perform many useless instrumental and laboratoristic exams and specialistic evaluations. In particular, electroencephalogram (EEG) is often prescribed as a first-line study in migraine patients. The objective is to analyze the indications of EEG in migraine and to evaluate whether its performance may negatively influence the time necessary to obtain a correct diagnosis. In particular, we compared the effects of EEG performance with those related to neuroradiological examinations in terms of time necessary to obtain a migraine diagnosis. 400 consecutive patients affected by migraine without aura were enrolled. Demographic and clinical data were collected. We used an ordinal regression model considering diagnostic delay as the main outcome and EEG and radiological examinations (in particular brain CT) as predictors. Delay was defined as a time to diagnosis greater than 1-year. Age, sex, number of specialists and examinations were included in the model as covariates. EEG represented the most often performed non-radiologic examination in our sample (20 %). It was associated with a significant risk of diagnostic delay [OR 1.66 (95 % CI 1.65-1.66, p < 0.001)]. An appropriate workup, including CT scan and early referral to a headache center was the most time-saving approach, being associated to the lowest probability of diagnostic delay [OR 0.72 (95 % CI 0.63-0.82, p < 0.001)]. EEG is a frequently prescribed exam in migraine. Our data show that it can contribute to diagnostic delay, highlighting only uncertain and unspecific elements. These data confirm the usefulness of a wide application of IHS guidelines, not recommending this exam for migraine detection.

Platelet amyloid precursor protein isoform expression in Alzheimer's disease: evidence for peripheral marker

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by a progressive cognitive and memory decline. Among peripheral markers of AD, great interest has been focused on the amyloid precursor protein (APP). In this regard, platelets represent an important peripheral source of APP since it has been demonstrated that the three major isoforms, that are constituted of 770, 751 and 695 aa residues, are inserted in the membrane of resting platelets. APP 751 and APP 770 contain a Kunitz-type serine protease inhibitor domain (APP KPI) and APP 695 lacks this domain. To address this issue, we first examined the platelet APP isoform mRNAs prospectively as biomarker for the diagnosis of AD by means of real-time quantitative PCR, and then evaluated the correlation between APP mRNA expression levels and cognitive impairment of enrolled subjects. Differential gene expression measurements in the AD patient group (n=18) revealed a significant up-regulation of APP TOT (1.52-fold), APP KPI (1.32-fold), APP 770 (1.33-fold) and APP 751 (1.26-fold) compared to controls (n=22). Moreover, a statistically significant positive correlation was found between APP mRNA levels (TOT, KPI, 770 and 751) and cognitive impairment. Since AD definitive diagnosis still relies on pathological evaluation at autopsy, the present results are consistent with the hypothesis that platelet APP could be considered a potential reliable peripheral marker for studying AD and could contribute to define a signature for the presence of AD pathology.

The role of instrumental examinations in delayed migraine diagnosis

Patients affected by migraine without aura very often consult different specialists who, misunderstanding the correct diagnosis, submit them to different instrumental examinations. The objective of the study was to assess if each instrumental examination was really useful for a faster migraine definition, or on the contrary, it increased the time delay for a correct diagnosis. We enrolled 300 consecutive patients referring to our Headache Center with a first diagnosis of migraine without aura and submitted them to a face-to-face interview about time from disease's onset to a correct diagnosis. In each patient, the first instrumental examination performed to specifically investigate migraine-related symptoms was defined. Brain MRI, brain CT, sinus CT, sinus X-rays, cervical spine X-rays and EEG were the most often performed examinations. All the exams, with the exception of brain CT, determined a significant increase of time delay in migraine diagnosis (p < 0.05). Brain CT was significantly associated with a higher probability to obtain a correct diagnosis in less than 1 year. Migraine without aura patients are usually addressed to perform radiological and other instrumental examinations. This attitude may increase the risk of time delay to obtain a correct diagnosis. The performance of a careful clinical history evaluation and neurological examination, with the addition of a brain CT when appropriate, is the best approach for a rapid and correct diagnosis of migraine without aura.

Applause sign: is it really specific for Parkinsonian disorders? Evidence from cortical dementias

OBJECTIVE

The applause sign, originally reported as a specific sign of progressive supranuclear palsy (PSP), has recently been found in several parkinsonian disorders. Its nature is still uncertain. It has been interpreted as a motor perseveration or a form of apraxia. The present study aims to: (a) verify the specificity of the applause sign for parkinsonian disorders, examining the presence of the applause sign in cortical dementias which should be error free and (b) clarify the nature of the applause sign (resulting or not from apraxia).

METHODS

77 subjects were included: 10 PSP, 15 frontotemporal dementia (FTD), 29 Alzheimer's disease (AD) and 23 normal controls. The presence of apraxia was an exclusion criterion. All patients underwent a detailed neuropsychological examination, and cognitive performance was correlated to the applause sign.

RESULTS

All patient groups showed the applause sign and differed significantly from normal subjects who were error free. No difference was found when comparing PSP with FTD and FTD with AD. AD differed significantly from PSP but they were not error free (31% of patients with AD showed the applause sign). The only correlation with background neuropsychology was found for measures of executive functions.

CONCLUSIONS

The presence of the applause sign in cortical dementia does not confirm the specificity of the applause sign for parkinsonian disorders. The applause sign should be interpreted as a sign of frontal lobe dysfunction rather than a form of apraxia, and can likely be detected in any kind of disease which involves frontal lobe structures to some extent.

Extracranial aneurysms of the posterior inferior cerebellar artery. Literature review and report of a new case

Aneurysms arising from the extracranial portion of the posterior-inferior cerebellar artery (PICA) are considered extremely rare. To date, only ten cases have been reported in the literature. The authors report a case of a 29 year-old male patient admitted comatose in Hunt-Hess grade IV because of an subarachnoid haemorrhage predominantly involving the left cranio-vertebral junction up to C2 rather than the posterior fossa and the fourth ventricle. Angiography showed an extracranial aneurysm at left vertebral artery-PICA junction a few millimetres superior to the dural entry point of the vertebral artery (VA). A left extreme-lateral approach was performed and the aneurysm was successfully clipped. On first year follow-up the patient had completely recovered with no neurological deficits. This paper analyzes the literature review about these rare aneurysms and the technical notes regarding the cranio-vertebral junction approach to these lesions. Factors affecting the neurological outcome of these aneurysms are also reported.

Foreign accent syndrome as the initial sign of primary progressive aphasia

Foreign accent syndrome (FAS) is a rare speech disorder characterised by the emergence of a new accent, perceived by listeners as foreign. FAS has usually been described following focal brain insults, such as stroke. We describe the unusual case of a woman presenting with FAS as the earliest symptom of progressive degenerative brain disease. At presentation, she showed no language or other cognitive impairment, and functional and structural brain imaging were normal. Follow-up 1 year later revealed the emergence of mild expressive language problems. Repeat functional neuroimaging showed mild hypoperfusion of the perisylvian speech area of the left hemisphere, and structural imaging showed mild left perisylvian atrophy. We interpret the case as an unusual presentation of primary progressive non-fluent aphasia. The case provides further evidence of the variable and circumscribed nature of the clinical presentation of focal cerebral degeneration.

Evolution of a prolactin-secreting pituitary microadenoma into a fatal carcinoma: a case report

Pituitary carcinomas are very rare tumors, nearly always presenting as widely invasive masses, although the hallmark of these lesions is the finding of distant metastases. One third of reported cases are prolactin (PRL)-secreting tumors. We report the case of a fatal pituitary carcinoma evolving within 4 years from a PRL-secreting microadenoma. A 22-year-old woman presented because of galactorrhea. Evaluation of the patient disclosed slight hyperprolactinemia and magnetic resonance imaging (MRI) showed a 7-mm intrapituitary lesion, which responded to treatment with cabergoline. About 4 years after the first evaluation she developed sudden headache, ptosis, and diplopia in the right eye. MRI disclosed the growth of a large pituitary mass, invading the right cavernous sinus. Despite two trans-sphenoidal surgical procedures followed by gamma-knife radiosurgery, the patient showed rapid local progression of the tumor and the occurrence of new lung lesions, probably of metastatic nature. The patient died 7 months after the development of her first neurological symptoms because of tumor apoplexy and subsequent subarachnoid hemorrhage. This case represents the first documented rapid evolution from a microprolactinoma initially responding to dopamine agonists to a fatal pituitary carcinoma.

Peroxynitrite production and NOS expression in astrocytes U373MG incubated with lipoproteins from Alzheimer patients

Apolipoprotein E (apo E), a plasma protein involved both in the metabolism of cholesterol and triglycerides, particularly in nervous tissue, has been associated with a higher risk of Alzheimer's disease. It has been shown that apo E increased the production of nitric oxide (NO) from human monocyte-derived macrophages (MDM); this effect could represent an important link between tissue redox balance and inflammation, since inflammation and oxidative stress are involved in chronic neurodegenerative disorders. Moreover, it has been evidenced that an overproduction of NO in the central nervous system (CNS) may play a key role in aging and that the glial cells (microglials cells and probably astrocytes) are able to form consistent amounts of NO through the induction of a nitric oxide synthase (iNOS) isoform so-called inducible or inflammatory. This report was performed in order to elucidate the effects produced by lipoproteins from control subjects, AD patients and first degree relatives (offspring) on human astrocyte cells after a short incubation. Peroxynitrite and NO production and NOS expression in cultured astrocytes were measured. We observed a decreased NO production after incubation with both LDL and HDL and an increased peroxynitrite production. As it concerns NOS expression, densitometric analysis of bands indicated that iNOS protein levels were significantly higher in the cells incubated with both AD lipoproteins and offspring lipoproteins compared to cells incubated with control lipoproteins. These findings suggest the possibility to identify in NO pathway a precocious marker of AD.

Modularity of music: evidence from a case of pure amusia

A case of pure amusia in a 20 year old left handed non-professional musician is reported. The patient showed an impairment of music abilities in the presence of normal processing of speech and environmental sounds. Furthermore, whereas recognition and production of melodic sequences were grossly disturbed, both the recognition and production of rhythm patterns were preserved. This selective breakdown pattern was produced by a focal lesion in the left superior temporal gyrus. This case thus suggests that not only linguistic and musical skills, but also melodic and rhythmic processing are independent of each other. This functional dissociation in the musical domain supports the hypothesis that music components have a modular organisation. Furthermore, there is the suggestion that amusia may be produced by a lesion located strictly in one hemisphere and that the superior temporal gyrus plays a crucial part in melodic processing.

Topographical disorientation consequent to amnesia of spatial location in a patient with right parahippocampal damage

We describe a patient who selectively lost the ability to orient himself in the environment after a stroke involving the right parahippocampal gyrus. The neuropsychological assessment showed a specific pattern of impairment of topographical memory; the patient recognised and recalled environmental landmarks but was unable to recall their spatial location. This study provides evidence that different forms of topographical disorientation may be related to distinct mechanisms of cognitive dysfunction. Furthermore, neuroimaging data suggest that a lesion of the right parahippocampal gyrus is critically related to pure topographical disorientation.

General anesthesia mode does not influence endocrine or immunologic profile after open or laparoscopic cholecystectomy

To verify the impact on stress response and the influence of anesthesia on endocrine/immunologic changes, we have investigated the plasma level of norepinephrine, cortisol, TNFalpha, and IL-6 in 46 patients scheduled for laparotomy and laparoscopic cholecystectomy at 2, 6, 12, and 24 h after the operation. Among subjects who underwent open approach, 9 received fentanyl anesthesia and 13 received isoflurane anesthesia. In the laparoscopy group, 14 patients were given fentanyl anesthesia and 10 were given isoflurane anesthesia. The results obtained confirmed that laparoscopic cholecystectomy is associated with a lesser immunoendocrine response, and the two anesthesia models do not interfere with plasma changes of the assessed hormones and cytokines.

Glycine-related amino acids stereoselectively affect N-methyl-D-aspartate receptor-mediated contractions of guinea pig ileum: comparison with the inhibition of strychnine-insensitive [3H]glycine binding to rat cortical membranes

Ten microM glycine, D-serine and D-alanine potentiated L-glutamate (30 microM)-induced contractions of the guinea pig ileum by an average of 35, 53 and 24%, respectively. On the contrary, D-cysteine, at the same concentration, caused a 21% inhibition of the contractile response to L-glutamate. This inhibitory effect of D-cysteine was abolished by 10 microM glycine. The corresponding L-isomers of these amino acids, namely L-serine, L-alanine and L-cysteine and the other amino acids tested, possessed negligible activity or were inactive in this test. The IC50 values of the same compounds for strychnine-insensitive binding of [3H]glycine (20 nM) to cortical membranes from the brain of the rat were: 0.26 microM, glycine; 1.2 microM, D-serine; 2.1 microM, D-alanine; 8.6 microM, D-cysteine; 51 microM, L-serine; 90 microM, L-alanine; greater than 1000 microM, L-cysteine. On the whole, these results point out a strict requirement for stereoselectivity for both of the effects examined. In addition, the results obtained in the ileum preparation suggest that D-cysteine may act as an antagonist, rather than as an agonist at the glycine site which regulates the responses of N-methyl-D-aspartate receptors.

Capsaicin and anaphylactic reactions in the guinea-pig

The influence of capsaicin on anaphylactic reactions in the guinea-pig was studied both in vivo and in vitro. In guinea-pigs actively sensitized with ovalbumin, Herxheimer microshock was elicited by antigen aerosol and the preconvulsion time recorded. The preconvulsion time was reduced by about 30% in animals pretreated with capsaicin (1 mg/kg) injected i.p. 30 min before antigen aerosol, whereas it remained unchanged when the drug was administered two days before aerosol treatment. Capsaicin shows a partial protective effect when the provocative aerosol was administered 3 h after the last of three doses of capsaicin (100 micrograms/kg, i.p.), which had been injected for three consecutive days. Ileum longitudinal muscle strips were used for in vitro anaphylaxis studies. These were isolated from guinea-pigs actively sensitized with ovalbumin and histamine release evoked by antigen was measured. Preparations perfused with capsaicin (10(-6)-10(-4) M) and desensitized to the drug, showed a lower anaphylactic release of histamine. This effect was dose-dependent, with the histamine release reduced by 35% at higher concentrations (10(-5)-10(-4) M) of capsaicin. The mechanism of the influence of capsaicin on anaphylactic reactions is discussed briefly.

Agonists, antagonists and modulators of excitatory amino acid receptors in the guinea-pig myenteric plexus

1. The receptors for glutamic acid (L-Glu) present in the guinea-pig myenteric plexus-ileal longitudinal muscle preparation have been studied by measuring the muscle contraction induced by numerous putative endogenous agonists acting at these receptors. Furthermore, the actions of different concentrations of antagonists, glycine, Mg2+ and Ca2+ on the ileal contractions induced by L-Glu have been evaluated. 2. The EC50 values of the most common putative endogenous agonists of these receptors were: L-Glu 1.9 X 10(-5) M; L-aspartate 8 X 10(-5) M; quinolinate 5 X 10(-4) M; L-homocysteate 1.4 X 10(-4) M; the dipeptide aspartyl-glutamate 8 X 10(-5) M, while N-acetyl-aspartyl-glutamate was inactive. Among the molecules used to classify excitatory amino acid receptors, N-methyl-D-aspartate (NMDA) was the most potent (EC50 5 X 10(-4) M). Kainic and quisqualic acids were almost completely inactive. 3. The responses to L-Glu were competitively antagonized by 2-amino-5-phosphonovaleric acid. They were, also, prevented by hyoscine (10(-7) M) and by tetrodotoxin (3 X 10(-7) M), suggesting that the L-Glu-induced ileal contraction was in some way dependent upon an action on the myenteric cholinergic neurones. Kynurenic acid was a non-competitive antagonist, gamma-D-glutamyl-taurine (10(-4) M) and aminophosphonobutyric acid (10(-4) M) did not modify the L-Glu-induced contractions. 4. Glycine (10(-5) M) significantly potentiated the effects of glutamate especially when the ionic composition of the superfusion medium contained concentrations of Ca2+ in the range of 0.6-1.2 mM. Strychnine 3 X 10(-5) M did not modify the actions of glycine. 5. The data presented here confirm the presence of NMDA receptors in the guinea-pig myenteric plexus, and show that these receptors, similar to those present in primary neuronal cultures may be modulated by glycine.

Decreased response to GABA-B agonists in longitudinal smooth muscle-myenteric plexus preparations from morphine-tolerant guinea-pigs

1) Responsiveness of guinea-pig ileal longitudinal smooth muscle-myenteric plexus preparations to drugs activating GABA-B receptors was studied in morphine-tolerant animals. For this purpose morphine pellets (75 mg each) were implanted subcutaneously in guinea-pigs and experiments were performed three days later in electrically-stimulated ileal strips. 2) Activation of GABA-B receptors with GABA (10(-6) -10(-3) M) or (-)-baclofen (10(-6)-10(-3) M) caused a dose-related inhibition of twitch response that was about 80% lower in preparations from morphine-tolerant animals than in controls. This was found both in preparations maintained in the presence of morphine (10(-6) M) and in morphine-free Krebs. The effect was evident also in ileal preparations from morphine-tolerant animals in which a withdrawal syndrome was induced by the administration of naloxone before sacrifice. 3) The phenomenon was specific since the dose-response curve of the adenosine-inhibitory effect was comparable in preparations from tolerant animals and controls. 4) The hyporesponsiveness to GABA-B receptor activation began 12 h after pellet implantation and was maximal on the third day. 5) It is concluded that during tolerance to and withdrawal from morphine there is a hyporesponsiveness of GABA-B receptors in "in vitro" guinea-pig ileal longitudinal muscle-myenteric plexus preparations.

Effects of nesosteine on Herxheimer microshock in guinea-pigs

In this paper we firstly report the inhibitory effect of nesosteine, a mucolytic drug, on Herxheimer microshock in guinea-pigs. Nesosteine (5-50 mg/kg) is able to protect sensitized animals from ovalbumin-induced bronchospasm. On the other hand, the drug is ineffective against the bronchospasm induced by histamine and acetylcholine. These results have also been confirmed in in vitro experiments where it has been demonstrated that nesosteine (10(-5) M) inhibits ovalbumin-induced histamine release in the trachea of sensitized animals. In the same preparation, the drug is ineffective against the contractions induced by histamine or acetylcholine. In conclusion, the drug presented here may be helpful in pathological conditions where reductions both of mucolysis and bronchospasm are sought.

Effect of various GABA-receptor agonists and antagonists on anaphylactic histamine release in the guinea-pig ileum

In this paper we confirm the previously reported inhibition by GABA of anaphylactic histamine release from isolated guinea-pig ileum longitudinal muscle. Moreover we report that: GABA-inhibition of anaphylactic histamine release is mimicked both by GABA-A and GABA-B agonists; both GABA-A and GABA-B antagonists are effective in reversing GABA's inhibitory effect; the effect is exerted specifically by GABA-ergic drugs: taurine and beta-alanine are ineffective; the GABA-ergic effect seems not to involve cholinergic and adrenergic transmission. It is concluded that it might be interesting to assess the clinical value of GABA-ergic drugs in allergic gut disorders.

Effect of baclofen on different models of bronchial hyperreactivity in the guinea-pig

In this paper we report an inhibitory effect of (-)-baclofen on many models of bronchial hyperreactivity both in vivo and in vitro. (-)-Baclofen protects guinea-pigs from the anaphylactic bronchospasm induced in sensitized animals by an ovalbumin aerosol and from that induced by aerosols of histamine and PGF2 alpha. Moreover (-)-baclofen reduces the TXA2 and TXB2 output induced by ovalbumin from isolated sensitized guinea-pig lungs. On the other hand (-)-baclofen does not show antihistaminic, anticholinergic or antiprostaglandinic action on isolated tracheal preparations. It is concluded that baclofen can provide protection from bronchial hyperreactivity possibly through a modulation of autonomic nervous system activity.

GABA-related activities of amino phosphonic acids on guinea-pig ileum longitudinal muscle

The effects of phosphonic analogues of GABA, beta-alanine and glycine on guinea-pig ileum longitudinal muscle were measured. Aminomethylphosphonic acid (AMPh) and 2-aminoethylphosphonic acid (2-AEPh) were devoid of any effect both in non-stimulated preparations and in electrically-stimulated preparations. The phosphonic analogue of GABA, 3-aminopropylphosphonic acid (3-APPh) possessed a GABAB agonistic effect (relaxation and inhibition of twitch response) at doses of 10(-3)M. No agonistic effect on GABAA receptors was observed. 3-APPh at doses tested (2 X 10(-4)M and 10(-3)M) also displayed antagonistic action on the effects of GABAB agonists producing a parallel shift of the log dose-effect curves of GABA- and (-)-baclofen-inhibition of twitch responses. In contrast 3-APPh did not antagonize the inhibitory effect of morphine and noradrenaline. The contractile effect of GABA, mediated via GABAA receptors, was unaffected by 3-APPh(10(-3)M). It is concluded that 3-APPh is a partial agonist at the GABAB site in guinea-pig ileum.

The presence of N-methyl-D-aspartate-type receptors for glutamic acid in the guinea pig myenteric plexus

The actions of agonists and antagonists of excitatory amino acid receptors were studied in the isolated ileal longitudinal muscle-myenteric plexus preparation of the guinea pig incubated 'in vitro', by recording the contraction of the longitudinal muscle. L-Glutamate, L-aspartate, quinolinate and N-methyl-D-aspartate (NMDA), in concentrations ranging from 10(-6) to 10(-4) M, induced a rapid contraction of this preparation while kainate and quisqualate were not active at a concentration of 10(-4) M. The excitatory amino acid responses were competitively antagonized by 2-amino-5-phosphonovalerate. They were also prevented by Mg2+ ions (0.1-1 mM), by tetrodotoxin 3 X 10(-6) M and by hyoscine 10(-7) M. The last observations suggest that the myenteric cholinergic interneurons are in some way involved in the glutamate-induced ileal contraction. These results demonstrate the existence of receptors for excitatory amino acids (possibly of NMDA type) in the myenteric plexus of the guinea pig.

The effect of lipoxygenase inhibitors and leukotriene antagonists on anaphylaxis

The experiments whose results are reported here were carried out with the aim of showing a possible role for lipoxygenase products in the modulation of the Schultz-Dale reaction. For this purpose, the actions of nordihydroguaieretic acid (NDGA) and of FPL 55712 were tested during anaphylaxis in guinea-pig ileum and trachea in vitro. Isolated preparations from guinea-pigs, which had been subcutaneously sensitized with ovalbumin and incomplete Freund adjuvant, were challenged with increasing concentrations of antigen; in preparations isolated from the same animal an antigen-concentration anaphylactic-reaction curve was performed in the presence of the drugs. NDGA 3.3 X 10(-6) M was capable of inhibiting anaphylaxis in the trachea to a maximum extent of 40% but it did not affect anaphylactic reaction in the intestinal smooth muscle. FPL 55712 2 X 10(-6) M did not exert any activity on anaphylaxis in either preparations. The difference between SRS-A and histamine as mediators of anaphylaxis in the tissue preparations used could explain the fact that NDGA acted on the trachea alone.

Effects of GABA agonists on Herxheimer microshock in guinea pigs

In this paper we describe the first observation of GABA inhibition in an experimental model of asthma in vivo. Guinea-pigs were actively sensitized with ovalbumin i.p. and 20 days later the Herxheimer microshock was performed. GABA and (-)-baclofen injected 20 min previously significantly prevented the development of microshock. Therefore GABAergic drugs appear to modulate in vivo anaphylactic reaction. The value of this observation with regard to the physiopathology and therapy of asthma remains to be elucidated.

Diazepam potentiates GABA-contraction in guinea-pig ileum

Both GABA-receptors and benzodiazepine receptors have recently been described in the ileum. In this work we tested whether an interaction between diazepam and GABA-A- or GABA-B-mediated effects took place in guinea-pig ileum longitudinal muscle. We found that diazepam dose-dependently (10(-9) M-10(-6) M) potentiates the contractions caused by the activation of GABA-A receptor while it is ineffective at the same doses on GABA-B- mediated effects (relaxation and inhibition of twitch response). The drug "per se" does not affect the ileum. Diazepam potentiation is specific since this drug does not potentiate contractions caused by acetylcholine (10(-8) M), 5-HT (10(-7) M), histamine (10(-7) M), and electrical stimulation. Diazepam potentiating effect was not evident in the presence of bicuculline (10(-5) M) or hyoscine (2 X 10(-7) M). Ro 15-1788 (10(-5)M) and beta CCE (10(-5)M) antagonized diazepam potentiation of GABA contraction, while PK 11195 (10(-5) M) was ineffective. We conclude that diazepam modulates the effects evoked by stimulation of peripheral GABA-A receptors, while it is ineffective on GABA-B mediated effects.

Modulatory activity of GABAB receptors on cholinergic tone in guinea-pig distal colon

The effect of gamma-aminobutyric acid (GABA) administration was studied in both in vitro and in vivo preparations of the guinea-pig distal colon. In in vitro preparations GABA (10(-7) - 10(-3) M) elicited a dose-dependent relaxation; a decrease in the spontaneous contractions was sometimes observed. The effect of GABA was mimicked by (-)-baclofen, which gave a dose-response curve overlapping that of GABA, while (+)-baclofen was about one hundred times less potent. The relaxation responses induced by the above drugs were antagonized by 5-aminovaleric acid (5 X 10(-4) M), which did not affect adenosine-induced relaxation, but they were insensitive to bicuculline (10(-5) M) and picrotoxin (10(-5) M). Moreover, they were prevented by tetrodotoxin (6 X 10(-7) M). In hyoscine (10(-7) M)-pretreated preparations, GABA still evoked a small relaxation response (approx. 10% of the maximum) that was bicuculline-sensitive. Desensitization to GABA (10(-5) M) was observed. A specific cross-desensitization occurred between GABA (10(-5) M) and (-)-baclofen (10(-5) M). In in vivo preparations, GABA (10 mumol kg-1) and (-)-baclofen (5 mumol kg-1) produced a dose-related inhibition of basal tone, while (+)-baclofen (5 mumol kg-1) had much less effect (about 25%). A decrease in the spontaneous contractions was sometimes observed. The relaxant effect of GABA and (-)-baclofen persisted in guinea-pigs pretreated (1-2 min) with picrotoxin (1.6 mumol kg-1), whereas it was significantly reduced in animals injected 1 min beforehand with 5-aminovaleric acid (0.2 mmol). The maximal relaxant effect induced by GABA and (-)-baclofen did not differ from that of atropine (0.9 mumol kg-1) and after atropine administration GABA had no further inhibitory effect. Relaxation responses induced by GABA and (-)-baclofen still occurred after blockade of nicotinic receptors by hexamethonium (0.17 mmol kg-1), which itself caused an increase in the basal tone. When the tone was increased by topical application of physostigmine (40 micrograms), GABA and (-)-baclofen induced a greater relaxation than that obtained in basal conditions. It is concluded that GABA, both in vitro and in vivo administration, inhibits cholinergic tone in guinea-pig distal colon and that this effect is mediated mainly by activation of GABAB receptors. Further experiments are required to ascertain the possible physiological role of a GABA-releasing neuronal system in the colon in vivo.

5-Aminovaleric acid interactions with GABAA and GABAB receptors in guinea-pig ileum

The potential interaction of 5-aminovaleric acid (5-AVA) on GABAA and GABAB receptors was investigated on the guinea-pig isolated ileum myenteric plexus preparation. In the unstimulated preparation 5-AVA (0.1-3 mM) produced a transient contraction which was abolished by previous exposure to picrotoxin (0.1 mM), atropine (3 microM) or tetrodotoxin (0.3 microM). Cross desensitization was observed between the contractile effects of 5-AVA and GABA, while a previous exposure to (+/-)-baclofen did not affect 5-AVA induced contractions. 5-AVA antagonized the relaxant effect of (+/-)-baclofen in unstimulated preparations. 5-AVA (1 mM) had no effect on amplitude of twitches in supramaximally stimulated preparations while GABA produced a concentration related inhibition. In the presence of 5-AVA (1 mM) the concentration response curve to GABA was shifted to the right without a reduction of the maximal effect attainable. These observations indicate that 5-AVA interacts with both GABAA and GABAB receptors in guinea-pig ileum. The concentrations required to observe a GABAA effect are of the same order as those which are effective in producing a blockade of GABAB mediated responses.

Influence of GABA on anaphylactic histamine release in vitro

In this preliminary report an unreported inhibitory action of GABA on anaphylactic reaction has been described. In a functional model (Schultz-Dale reaction) GABA has been demonstrated to inhibit the antigen-evoked contraction. This effect depends on a modulation of anaphylactic histamine release. The phenomenon is dose-dependent and requires a period of time to develop. Since GABAergic neurons are present in the preparation, it is possible to speculate that GABA receptors are involved in this inhibitory action. However, pharmacological analysis of the phenomenon has to be carried out, especially in view of the latency of GABA to develop its effect.

Neurological disorders of the myenteric plexus: a review

The myenteric plexus is the neuronal complex that regulates the motility of the gut; a brief review of its pathology is presented in this paper as well as a tentative etiopathogenetic classification. Disorders of gut innervation include congenital (e.g. Hirschsprung's disease) or acquired diseases; the latter can be idiopathic or related to a more general pathological involvement of the whole organism as in the case of bacterial toxins, diabetes mellitus, Riley-Day disease and primary orthostatic hypotension. In view of the fundamental similarity of the myenteric plexus to the central nervous system, the study of this organ can be useful both for diagnosis of degenerative diseases of the central nervous system (i.e. via rectal biopsy) and for gaining a better etiopathogenetic insight into peripheral and central nervous system disease.

Homotaurine: a GABAB antagonist in guinea-pig ileum

Homotaurine (3-aminopropane sulphonic acid) did not inhibit the twitch response in guinea-pig ileum longitudinal muscle whilst gamma-aminobutyric acid (GABA) and (-)-baclofen evoked dose-dependent inhibitions. The inhibitory effects of GABA and (-)-baclofen were prevented in the presence of homotaurine 2 X 10(-4) and 10(-3) M. The log dose-effect curves of GABA and (-)-baclofen were shifted in a parallel manner compatible with competitive antagonism. The pA2 of homotaurine with GABA (4.22 +/- 0.05) and (-)-baclofen (4.26 +/- 0.1) were the same. Homotaurine did not antagonize the inhibitory effects of morphine (ED50 4 X 10(-7) M), noradrenaline (ED50 10(-6) M) or ATP (ED50 1.5 X 10(-5) M). The inferior homologue of homotaurine, taurine 10(-3) M, did not modify the inhibitory effects of GABA and (-)-baclofen. Picrotoxin 5 X 10(-5) M antagonized GABAA receptor-mediated contraction but did not affect GABAB receptor-mediated inhibition. At the same concentration the drug did not influence the antagonistic action of homotaurine, thus showing no GABAA receptor-mediated interference. It may be concluded that homotaurine is a competitive antagonist of GABAB mediated effects in the guinea-pig ileum.

GABAA and GABAB receptor-mediated effects in guinea-pig ileum

1 The effects of gamma-aminobutyric acid (GABA) and related substances were examined in guinea-pig ileum longitudinal muscle.2 GABA at doses ranging from 10(-7) M to 3 x 10(-6) M elicited a relaxation while at higher doses (3 x 10(-6) M - 10(-4) M), as previously described, it caused a contraction followed by relaxation.3 GABA-induced relaxation was bicuculline-insensitive, was mimicked by (-)-baclofen but not by homotaurine and muscimol. The effect of baclofen was stereospecific. GABA- and (-)-baclofen-induced relaxations were dose-dependent and their ED(50) values were similar. A specific cross-desensitization occurred between GABA and (-)-baclofen.4 The bicuculline-insensitive relaxation induced by GABA and (-)-baclofen was prevented by tetrodotoxin and hyoscine but not by phentolamine plus propranolol, naloxone or theophylline.5 In preparations in which the muscle tone was raised by histamine or prostaglandin F(2alpha), GABA and (-)-baclofen induced relaxation to the same extent as before increasing the tone. If the tone was raised by DMPP, a greater bicuculline-insensitive relaxation occurred.6 Contraction caused by GABA was bicuculline-sensitive and was mimicked by homotaurine and muscimol. Contraction was dose-dependent and muscimol was about three times more potent than GABA or homotaurine. A specific cross-desensitization occurred between the contractile effects of GABA and those of homotaurine or muscimol.7 Bicuculline competitively antagonized the contractile effects of GABA, homotaurine and muscimol and gave closely similar pA(2) values. The slope of the Schild plot for the above drugs was near 1, confirming the competitive nature of the antagonism.8 The bicuculline-sensitive contraction induced by GABA, homotaurine and muscimol was abolished by tetrodotoxin and was non-competitively antagonized by hyoscine, while it was unaffected by hexamethonium, mepyramine and methysergide.9 It is concluded that two receptors mediate the GABA effects in guinea-pig ileum: a bicuculline-sensitive GABA(A) receptor, which elicits contraction through an excitatory action on cholinergic post-ganglionic neurones; and a bicuculline-insensitive GABA(B) receptor which causes relaxation through an inhibitory presynaptic action on cholinergic post-ganglionic neurones. We confirm that GABA, homotaurine and muscimol are GABA(A) agonists, while GABA and (-)-baclofen are GABA(B) agonists.