Seroprevalence and risk factors of brucellosis in goats in selected states in Nigeria and the public health implications.

Available reports on brucellosis in Nigeria are largely confined to cattle while it is believed that other ruminants like sheep and goats are equally exposed to the disease. To have an insight into the role of goats in the epidemiology of brucellosis in Nigeria, we conducted a cross-sectional study between June 2011 and May 2013 to determine the seroprevalence of brucellosis in goats in some selected states in Nigeria. Serum samples were collected from goats at different locations and tested for antibodies to Brucella spp using the Rose Bengal Test (RBT), samples positive by RBT were further subjected to Competitive Enzyme Linked Immunosorbent Assay (cELISA). Data collected to determine risk factors were also analysed using chi-square and logistics regression statistics. Out of a total of 2827 samples tested from the different states (Benue = 331; Borno =195; Oyo = 2155; Sokoto = 146), we recorded an overall seroprevalence of 2.83% (Benue = 17.30%; Borno = 2.05%; Oyo = 0.60% and Sokoto = 0.00%) by RBT. The cELISA further supported 9.45% (7/74) of the total RBT positive samples. Logistic regression analysis showed that the location (p = 0.004) and source (p < 0.0001); are probable risk factors to be considered in the epidemiology of brucellosis with sex (p = 0.179); age (p = 0.791) and breed (p = 0.369) not playing any major role. Our findings reveal a relatively low seroprevalence of brucellosis among goats screened except for Benue State. Since most of the goats sampled in the present study were from the abattoirs, further farm level investigations are required to determine the role of goats in the epidemiology of brucellosis in Nigeria since they share common environment with sheep and cattle that are natural hosts of Brucella species which are of major public health threat.

Inferior temporal sulcus as a site of corticotomy: magnetic resonance imaging analysis of individual sulcus patterns.

OBJECTIVE: Transcortical approaches to the inferior horn often result in quadrant hemianopsia attributable to the injury to the optic radiation. The inferior temporal sulcus (ITS) has received little attention as an entrance point for the transsulcal approach. We used the method of detecting the ITS with magnetic resonance imaging (MRI) scans and investigated the sulcus pattern of ITS, its incidence rate, and the availability of the ITS to the corticotomy for selective amygdalohippocampectomy. METHODS: The sulcus patterns of the ITS of 100 temporal lobes in 50 healthy individuals were classified according to the number of interruptions by gyral bridges, and the localization of the ITS was characterized in relation to the outer surface by means of the surface anatomy scan of MRI. RESULTS: Most of the ITS was interrupted by one to three gyral bridges (0 bridges, 8%; one bridge, 27%: two bridges, 37%; three bridges, 20%; more than four bridges or no apparent ITS, 8%). When the ITS was present, it was located 15 mm above the orbitotragus line at a point 20 mm anterior to the tragus. The number of gyral bridges was significantly larger in the left temporal lobes than in the right temporal lobes, regardless of the sex of the subject. CONCLUSION: The ITS was clearly identified in 72% of the temporal lobes by the oblique sagittal view of MRI scans; thus, in such cases, the ITS was considered to be a candidate for an entrance point of a small temporal corticotomy. The preoperative observation of the ITS in relation to the orbitotragus line by means of MRI may improve the planning of the transsulcal approaches to deeply seated mesial temporal lesions, such as hippocampal sclerosis.

Role of Raf-1 conserved region 2 in regulation of Ras-dependent Raf-1 activation.

Full activation of Raf-1 requires the interaction of its CRD with Ras. The serine/threonine-rich region, CR2, of Raf-1 was implicated in Raf-1 regulation, but the underlying mechanism was unclear. Here we show that CRD loses its Ras-binding activity when expressed in connection with CR2, suggesting that CR2 masks CRD. This masking effect is abolished by substitution of Asp or Ala for Ser-259, a growth factor- and TPA-induced phosphorylation site in CR2. Treatment of COS-7 cells expressing Ha-Ras(Val-12) and Raf-1 with TPA enhances the Ha-Ras(Val-12)-dependent Raf-1 kinase activity. In contrast, the Ha-Ras(Val-12)-dependent activities of the Raf-1(S259D) and Raf-1(S259A) mutants are comparable to that of wild-type Raf-1 stimulated by both Ha-Ras(Val-12) and TPA and cannot be further stimulated by TPA treatment. These results suggest that the in vivo phosphorylation of Ser-259 may comprise a crucial step for Ras-dependent Raf-1 activation by unmasking CRD and promoting its association with Ras.

Association of yeast adenylyl cyclase with cyclase-associated protein CAP forms a second Ras-binding site which mediates its Ras-dependent activation.

Posttranslational modification, in particular farnesylation, of Ras is crucial for activation of Saccharomyces cerevisiae adenylyl cyclase (CYR1). Based on the previous observation that association of CYR1 with cyclase-associated protein (CAP) is essential for its activation by posttranslationally modified Ras, we postulated that the associated CAP might contribute to the formation of a Ras-binding site of CYR1, which mediates CYR1 activation, other than the primary Ras-binding site, the leucine-rich repeat domain. Here, we observed a posttranslational modification-dependent association of Ras with a complex between CAP and CYR1 C-terminal region. When CAP mutants defective in Ras signaling but retaining the CYR1-binding activity were isolated by screening of a pool of randomly mutagenized CAP, CYR1 complexed with two of the obtained three mutants failed to be activated efficiently by modified Ras and exhibited a severely impaired ability to bind Ras, providing a genetic evidence for the importance of the physical association with Ras at the second Ras-binding site. On the other hand, CYR1, complexed with the other CAP mutant, failed to be activated by Ras but exhibited a greatly enhanced binding to Ras. Conversely, a Ras mutant E31K, which exhibits a greatly enhanced binding to the CYR1-CAP complex, failed to activate CYR1 efficiently. Thus, the strength of interaction at the second Ras-binding site appears to be a critical determinant of CYR1 regulation by Ras: too-weak and too-strong interactions are both detrimental to CYR1 activation. These results, taken together with those obtained with mammalian Raf, suggest the importance of the second Ras-binding site in effector regulation.

Posteroventral pallidotomy for midbrain tremor after a pontine hemorrhage. Case report.

This 49-year-old man gradually developed a disabling action tremor in the proximal right upper extremity 8 months after suffering a pontine tegmental hemorrhage. The intraoperative microrecording in the nucleus ventralis intermedius (VIM) of the left thalamus revealed tremor-synchronous grouped discharges with a vigorous (2.7 Hz) action tremor predominantly in the shoulder and upper arm. High frequency electrical stimulation in the VIM did not affect the tremor. A posteroventral pallidotomy (PVP) was performed and resulted in the successful alleviation of all tremor activity. Posteroventral pallidotomy is known to alleviate parkinsonian tremors, especially those occurring in the contralateral lower extremity, trunk, and proximal segment of the contralateral upper extremity. The authors consider the pallidoreticular pathway to be an important tremor-mediating pathway for the proximal segment of the upper extremities and believe it can be controlled more effectively by PVP than by VIM thalamotomy, as demonstrated by the PVP-induced resolution of the midbrain tremor observed in this case.

Tremor induced by toluene misuse successfully treated by a Vim thalamotomy.

A 22 year old man developed a vigorous tremor of 5 Hz in his right hand, after a 7 year history of toluene misuse. T2 Weighted MRI depicted marked decreases in the signal intensity of the basal ganglia, red nucleus, and thalamus on both sides. The stereotactic coagulation of the left nucleus ventrointermedius (Vim) of the thalamus abolished the tremors in his right hand. This patient clearly exhibited the pathological involvement of rubral lesions in generation of a toluene induced tremor on MRI. Toluene induced tremor is an irreversible symptom which persists even after stopping toluene misuse, therefore in medically intractable cases, it should be positively treated by a Vim thalamotomy.

Characterization of a novel Ras-binding protein Ce-FLI-1 comprising leucine-rich repeats and gelsolin-like domains.

Ras proteins are conserved from yeasts to mammals and implicated in regulation of the actin cytoskeleton. The flightless-1 (fli-1) gene of Drosophila melanogaster and its homologs in Caenorhabditis elegans and humans encode proteins (FLI-1) comprising a fusion of a leucine-rich repeats (LRRs) domain and a gelsolin-like domain. This LRRs domain is highly homologous to those of three proteins involved in Ras-mediated signaling; Saccharomyces cerevisiae adenylyl cyclase, C. elegans SUR-8, and mammalian RSP-1. Here we report that the LRRs domain of C. elegans FLI-1 (Ce-FLI-1) associates directly with Ras (Kd = 11 nM) and, when overexpressed, suppresses the heat shock sensitive phenotype of yeast cells bearing the activated RAS2 gene (RAS2(Val-19)). Further, the gelsolin-like domain of Ce-FLI-1 is shown to possess a Ca2+-independent G-actin-binding activity as well as F-actin-binding and -severing activities. FLI-1 may be involved in regulation of the actin cytoskeleton through Ras.

Coiled-coil interaction of N-terminal 36 residues of cyclase-associated protein with adenylyl cyclase is sufficient for its function in Saccharomyces cerevisiae ras pathway.

In the budding yeast Saccharomyces cerevisiae, association with the 70-kDa cyclase-associated protein (CAP) is required for proper response of adenylyl cyclase to Ras proteins. We show here that a small segment comprising the N-terminal 36 amino acid residues of CAP is sufficient for association with adenylyl cyclase as well as for its function in the Ras-adenylyl cyclase pathway as assayed by the ability to confer RAS2(Val-19)-dependent heat shock sensitivity to yeast cells. The CAP-binding site of adenylyl cyclase was mapped to a segment of 119 amino acid residues near its C terminus. Both of these regions contained tandem repetitions of a heptad motif alphaXXalphaXXX (where alpha represents a hydrophobic amino acid and X represents any amino acid), suggesting a coiled-coil interaction. When mutants of CAP defective in associating with adenylyl cyclase were isolated by screening of a pool of randomly mutagenized CAP, they were found to carry substitution mutations in one of the key hydrophobic residues in the heptad repeats. Furthermore, mutations of the key hydrophobic residues in the heptad repeats of adenylyl cyclase also resulted in loss of association with CAP. These results indicate the coiled-coil mechanism as a basis of the CAP-adenylyl cyclase interaction.

Identification of PLC210, a Caenorhabditis elegans phospholipase C, as a putative effector of Ras.

Mammalian Ras proteins regulate multiple effectors including Raf, Ral guanine nucleotide dissociation stimulator (RalGDS), and phosphoinositide 3-kinase. In the nematode Caenorhabditis elegans, LIN-45 Raf has been identified by genetic analyses as an effector of LET-60 Ras. To search for other effectors in C. elegans, we performed a yeast two-hybrid screening for LET-60-binding proteins. The screening identified two cDNA clones encoding a phosphoinositide-specific phospholipase C (PI-PLC) with a predicted molecular mass of 210 kDa, designated PLC210. PLC210 possesses two additional functional domains unseen in any known PI-PLCs. One is the C-terminal Ras-associating domain bearing a structural homology with those of RalGDS and AF-6. This domain, which could be narrowed down to 100 amino acid residues, associated in vitro with human Ha-Ras in a GTP-dependent manner and competed with yeast adenylyl cyclase for binding Ha-Ras. The binding was abolished by specific mutations within the effector region of Ha-Ras. The other functional domain is the N-terminal CDC25-like domain, which possesses a structural homology to guanine nucleotide exchange proteins for Ras. These results strongly suggest that PLC210 belongs to a novel class of PI-PLC, which is a putative effector of Ras.

Visual evoked potentials in the vicinity of the optic tract during stereotactic pallidotomy.

We recorded visual evoked responses in eight patients with Parkinson's disease, using a depth electrode either at or below the stereotactic target in the ventral part of the globus pallidus internus (GPi), which is located immediately dorsal to the optic tract. Simultaneously, scalp visual evoked potentials (VEPs) were also recorded from a mid-occipital electrode with a mid-frontal reference electrode. A black-and-white checkerboard pattern was phase reversed at 1 Hz; check size was 50 min of arc . Pallidal VEPs to full field stimulation showed an initial positive deflection, with a latency of about 50 ms (P50), followed by a negatively with a mean latency of 80 ms (N80). The mean onset latency of P50 was about 30 ms. P50 and N80 were limited to the ventralmost of the GPi and the ansa lenticularis. Left half field stimulation evoked responses in the right ansa lenticularis region while right half field stimulation did not, and vice versa. These potentials thus seemed to originate posterior to the optic chiasm. The scalp VEPs showed typical triphasic wave forms consisting of N75, P100 and N145. The location of the recording electrode in the ansa lenticularis region did not modify the scalp VEP. These results suggest that P50 and N80 are near-field potentials reflecting the compound action potentials from the optic tract. Therefore, N75 of the scalp VEPs may represent an initial response of the striate cortex but not of the lateral geniculate nucleus.

[Roles of the basal ganglia outputs in movement disorders: a viewpoint based on experiences of stereotactic surgery for idiopathic dystonia].

Ventrolateral (VL)-thalamotomy and posteroventral pallidotomy were carried out in 37 patients with idiopathic dystonia, including 23 with dystonia musculorum deformans, 12 with Meige syndrome and 2 with focal dystonia. There were 11 patients with the onset age of dystonia below 10 years and 26 with the age above 11 years. Dystonia tended to generalize in the pediatric patients and to localize to the palmo-mental region in the adult patients. VL-thalamotomy in 30 patients improved the upper body dystonia especially in the adult patients, but, often failed to benefit the pediatric patients. Posteroventral pallidotomy in 18 patients dramatically alleviated the generalized dystonia especially in the pediatric patients. In one adult patient, pallidotomy caused hemiparesis due to intracerebral hemorrhage. The internal pallidum projects the efferents to the thalamic motor nuclei and also to the brainstem reticular formation that connects to the spinal motoneurons. The present findings implicate the descending pallido-reticular pathway in the mechanism of dystonia of pediatric patients, and the ascending pallido-thalamic pathway in that of adult patients.

Effect of association with adenylyl cyclase-associated protein on the interaction of yeast adenylyl cyclase with Ras protein.

Posttranslational modification of Ras protein has been shown to be critical for interaction with its effector molecules, including Saccharomyces cerevisiae adenylyl cyclase. However, the mechanism of its action was unknown. In this study, we used a reconstituted system with purified adenylyl cyclase and Ras proteins carrying various degrees of the modification to show that the posttranslational modification, especially the farnesylation step, is responsible for 5- to 10-fold increase in Ras-dependent activation of adenylyl cyclase activity even though it has no significant effect on their binding affinity. The stimulatory effect of farnesylation is found to depend on the association of adenylyl cyclase with 70-kDa adenylyl cyclase-associated protein (CAP), which was known to be required for proper in vivo response of adenylyl cyclase to Ras protein, by comparing the levels of Ras-dependent activation of purified adenylyl cyclase with and without bound CAP. The region of CAP required for this effect is mapped to its N-terminal segment of 168 amino acid residues, which coincides with the region required for the in vivo effect. Furthermore, the stimulatory effect is successfully reconstituted by in vitro association of CAP with the purified adenylyl cyclase molecule lacking the bound CAP. These results indicate that the association of adenylyl cyclase with CAP is responsible for the stimulatory effect of posttranslational modification of Ras on its activity and that this may be the mechanism underlying its requirement for the proper in vivo cyclic AMP response.

Differential structural requirements for interaction of Ras protein with its distinct downstream effectors.

Ras proteins have multiple effectors of distinct structures that do not share significant structural homology at their Ras interaction sites. To prove possible differences in their recognition mechanisms of Ras, we screened 44 human Ha-Ras proteins carrying mutations in the effector region and its flanking sequences for interaction with human Raf-1, Schizosaccharomyces pombe Byr2, and Saccharomyces cerevisiae adenylyl cyclase. The Ras binding specificities were largely shared between Raf-1 and Byr2 although Ras mutants, Y32F, T35S, and A59E, had their affinities for Byr2 selectively reduced. The only exception was Ras(D38N), which lost the ability to bind Raf-1 while retaining the activity to bind Byr2 and complement the Byr2- phenotype of S. pombe. On the other hand, adenylyl cyclase had quite distinct requirements for Ras residues; mutations P34G and T58A selectively abolished the ability to bind and activate it without considerably affecting the interaction with Raf-1 and Byr2. Y32F mutant, whereas losing the ability to activate Raf-1 and Byr2, could activate adenylyl cyclase efficiently. In addition, V45E mutation was found to impair the ability of Ras to activate both Raf-1 and adenylyl cyclase without significantly affecting the binding affinities for them. These results demonstrate that significant differences exist in the recognition mechanisms by which the three effector molecules associate with Ras and suggest that a region of Ras required for activation of the effectors in general may exist separately from that for binding the effectors.

Surgical control of akinesia in Parkinson's disease.

Posteroventral pallidotomy (PVP) was carried out in 86 patients with Parkinson's disease, who presented marked bradykinesia, freezing of gait and postural defect associated with rigidity and tremor in 82 patients (bradykinesia type), and similar gait and postural problems with minimum signs of rigidity and tremor in 4 (pure akinesia type). The stereotactic coordinates of Leksell's device were calculated from MRI and conventional ventriculography. The final target was defined by microelectrode techniques in the basal ganglia. The microrecording study revealed a very high background activity in the internal pallidum in patients of the bradykinetic type, however, a much lower pallidal activity in patients of the pure akinesia type. Fifty-eight patients underwent unilateral PVP, and 28 underwent bilateral surgery. Following PVP, rigidity tremor and poor reciprocal movements were significantly improved especially in the contralateral extremities. The most dramatic findings were the reversal of akinetic symptoms and wearing-off phenomena. The patients were followed up for 3-30 months (mean = 8) after surgery. Of the 82 bradykinesia type patients, good result were obtained in 48 (58%), fair results in 26 (32%), and minor improvement or no change in 8 (10%). In all the 4 patients of the pure akinesia type, recurrence of the akinetic symptoms occurred after a temporal improvement lasting a few days to 3 month after surgery. There was worst dysarthria in 3 patients, hemiparesis in 1 and partial motor aphasia in 1. The visual field problem was not complicated in any patients. These findings suggest that akinetic symptoms in PD are implicated in overactive pallidal outputs with putative GABAergic modulator by excessively inhibiting pedunculopontine nucleus activity (midbrain locomotor and posture regions) as well as thalamic activity. Partial interruption of the pallidal efferents eliminates the akinetic symptoms by disinhibitory effects on the target structures. The pathology of PD of the pure akinesia type is supposedly in the brainstem and should be excluded from indication of pallidotomy.

Juvenile parkinsonism treated with bilateral pallidotomies--case report.

A 47-year-old female diagnosed as having juvenile parkinsonism at age 38 years developed progressive motor fluctuation while receiving levodopa medication. She underwent right posteroventral pallidotomy which achieved only a transient effect on the wearing-off. An additional procedure on the left pallidum resulted in long-lasting relief of the parkinsonian symptoms.

The results, indications, and physiology of posteroventral pallidotomy for patients with Parkinson's disease.

In the past, stereotactic surgical intervention for Parkinson's disease was considered indicated only in those patients with active motor manifestations that were refractory to pharmacological therapy, manifestations such as tremor, rigidity, dystonia, and dyskinesia. With the reintroduction and refinement of Leksell's posteroventral pallidotomy, both akinetic and hyperkinetic symptoms are now amenable to surgical treatment. We have analyzed the results of 126 patients who underwent either unilateral (n = 58) or bilateral (n = 68) posteroventral pallidotomies. The Unified Parkinson's Disease Rating Scale and Hoehn and Yahr Staging Scale were used for preoperative and postoperative objective assessments. Postoperative follow-up evaluation occurred initially at 1 week and subsequently at intervals between 1 and 12 months (mean = 4.5 months) after surgery. Although individual motor subscores on the Unified Parkinson's Disease Rating Scale were significantly reduced (n = 126, P < or = 0.01), the most dramatic findings were the reversal of akinetic symptoms and the elimination of dyskinesia and profound "off" periods. These clinical results, combined with intraoperative microelectrode records revealing pallidal neuronal hyperactivity, suggest a reconsideration of the pathophysiology of akinesia and point to possible mechanisms of akinesia improvement by posteroventral pallidotomy in some parkinsonian subgroups.