Transmission-Blocking Vaccines for Canine Visceral Leishmaniasis: New Progress and Yet New Challenges

Dogs with visceral leishmaniasis play a key role in the transmission cycle of Leishmania infantum to humans in the urban environment. There is a consensus regarding the importance of developing a vaccine to control this disease. Despite many efforts to develop a protective vaccine against CVL, the ones currently available, Leish-tec® and LetiFend®, have limited effectiveness. This is due, in part, to the complexity of the immune response of the naturally infected dogs against the parasite and the complexity of the parasite transmission cycle. Thus, strategies, such as the development of a transmission-blocking vaccines (TBVs) already being applied to other vector-borne diseases like malaria and dengue, would be an attractive alternative to control leishmaniasis. TBVs induce the production of antibodies in the vertebrate host, which can inhibit parasite development in the vector and/or interfere with aspects of vector biology, leading to an interruption of parasite transmission. To date, there are few TBV studies for CVL and other leishmaniasis forms. However, the few studies that exist show promising results, thus justifying the further development of this approach.

Vaccination with Formulation of Nanoparticles Loaded with Leishmania amazonensis Antigens Confers Protection against Experimental Visceral Leishmaniasis in Hamster

Visceral leishmaniasis (VL) is a fatal disease caused by the protozoa Leishmania infantum for which dogs are the main reservoirs. A vaccine against canine visceral leishmaniasis (CVL) could be an important tool in the control of human and CVL by reducing the infection pressure of L. infantum. Despite the CVL vaccine available on the market, the Brazilian Ministry of Health did not implement the use of it in their control programs. In this sense, there is an urgent need to develop more efficient vaccines. In this study, the association between two polymeric nanoformulations, (poly (D, L-lactic) acid (PLA) polymer) loading Leishmania amazonensis antigens, was evaluated as a potential immunobiological agent against VL using golden hamsters as an experimental model. The results indicated that no significant adverse reactions were observed in animals vaccinated with LAPSmP. LAPSmP presented similar levels of total anti-Leishmania IgG as compared to LAPSmG. The LAPSmP and LAPSmG groups showed an intense reduction in liver and spleen parasitic load by qPCR. The LAPSmP and LAPSmG vaccines showed exceptional results, indicating that they may be promising candidates as a VL vaccine.

Kinetics of Phenotypic and Functional Changes in Mouse Models of Sponge Implants: Rational Selection to Optimize Protocols for Specific Biomolecules Screening Purposes

The sponge implant has been applied as an important in vivo model for the study of inflammatory processes as it induces the migration, proliferation, and accumulation of inflammatory cells, angiogenesis, and extracellular matrix deposition in its trabeculae. The characterization of immune events in sponge implants would be useful in identifying the immunological events that could support the selection of an appropriate experimental model (mouse strain) and time post-implant analysis in optimized protocols for novel applications of this model such as in biomolecules screening. Here, the changes in histological/morphometric, immunophenotypic and functional features of infiltrating leukocytes (LEU) were assessed in sponge implants for Swiss, BALB/c, and C57BL/6 mice. A gradual increase of fibrovascular stroma and a progressive decrease in LEU infiltration, mainly composed of polymorphonuclear cells with progressive shift toward mononuclear cells at late time-points were observed over time. Usually, Swiss mice presented a more prominent immune response with late mixed pattern (pro-inflammatory/anti-inflammatory: IL-2/IFN-γ/IL-4/IL-10/IL-17) of cytokine production. While BALB/c mice showed an early activation of the innate response with a controlled cytokine profile (low inflammatory potential), C57BL/6 mice presented a typical early pro-inflammatory (IL-6/TNF/IFN-γ) response with persistent neutrophilic involvement. A rational selection of the ideal time-point/mouse-lineage would avoid bias or tendentious results. Criteria such as low number of increased biomarkers, no recruitment of cytotoxic response, minor cytokine production, and lower biomarker connectivity (described as biomarker signature analysis and network analysis) guided the choice of the best time-point for each model (Day5/Swiss; Day7/BALB/c; Day6/C57BL/6) with wide application for screening purposes, such as identification of therapeutic biomolecules, selection of antigens/adjuvants, and follow-up of innate and adaptive immune response to vaccines candidates.

In vitro Infectivity of Strains Isolated From Dogs Naturally Infected With Leishmania infantum Present a Distinct Pathogenic Profile in Hamsters

Visceral leishmaniasis (VL) is a severe disease caused by Leishmania infantum. Dogs are the parasite's main reservoir, favoring its transmission in the urban environment. The analysis of L. infantum from infected dogs contributes to the identification of more virulent parasites, thereby supporting basic and applied studies such as vaccinal and therapeutic strategies. We proposed the in vitro and in vivo characterization of L. infantum strains from naturally infected dogs from a VL endemic area based on an infectivity and pathogenicity analysis. DH82 canine macrophages were infected in vitro with different strains for infectivity analysis, showing distinct infectivity profiles. The strains that showed greater and lesser infectivity using in vitro analyses (616 and 614, respectively) were used to infect hamsters for pathogenicity analysis. The group infected with strain 616 showed 100% survival while the group infected with strain 614 showed 50% after seven months of follow up. Furthermore, the 614 strain induced more noticeable clinicopathological changes and biochemical abnormalities in liver function, along with high inflammation and parasite load in the liver and spleen. We confirmed high variability of infectivity and pathogenicity in L. infantum strains from infected dogs. The results support the belief that screening for L. infantum infectivity using in vitro experiments is inadequate when it comes to selecting the most pathogenic strain.

Historical Perspective and Biotechnological Trends to Block Arboviruses Transmission by Controlling Aedes aegypti Mosquitos Using Different Approaches

Continuous climate changes associated with the disorderly occupation of urban areas have exposed Latin American populations to the emergence and reemergence of arboviruses transmitted by Aedes aegypti. The magnitude of the financial and political problems these epidemics may bring to the future of developing countries is still ignored. Due to the lack of effective antiviral drugs and vaccines against arboviruses, the primary measure for preventing or reducing the transmission of diseases depends entirely on the control of vectors or the interruption of human-vector contact. In Brazil the first attempt to control A. aegypti took place in 1902 by eliminating artificial sites of eproduction. Other strategies, such as the use of oviposition traps and chemical control with dichlorodiphenyltrichlorethane and pyrethroids, were successful, but only for a limited time. More recently, biotechnical approaches, such as the release of transgenics or sterile mosquitoes and the, development of transmission blocking vaccines, are being applied to try to control the A. aegypti population and/or arbovirus transmission. Endemic countries spend about twice as much to treat patients as they do on the prevention of mosquito-transmitted diseases. The result of this strategy is an explosive outbreak of arboviruses cases. This review summarizes the social impacts caused by A. aegypti-transmitted diseases, mainly from a biotechnological perspective in vector control aimed at protecting Latin American populations against arboviruses.

An Overview of Immunotherapeutic Approaches Against Canine Visceral Leishmaniasis: What Has Been Tested on Dogs and a New Perspective on Improving Treatment Efficacy

Visceral leishmaniasis (VL), caused by digenetic protozoa of the genus Leishmania, is the most severe form of leishmaniasis. Leishmania infantum is one of the species responsible for VL and the disease caused is considered a zoonosis whose main reservoir is the dog. Canine visceral leishmaniasis (CVL) can lead to the death of the animal if left untreated. Furthermore, the available pharmocologial treatment for CVL presents numerous disadvantages, such as relapses, toxicity, drug resistance, and the fact treated animals continue to be reservoirs when treatment fails to achieve parasitological cure. Moreover, the available VL control methods have not been adequate when it comes to controlling parasite transmission. Advances in immune response knowledge in recent years have led to a better understanding of VL pathogenesis, allowing new treatments to be developed based on immune system activation, often referred to as immunotherapy. In fact, well-defined protocols have been described, ranging from the use of immunomodulators to the use of vaccines. This treatment, which can also be associated with chemotherapy, has been shown to be effective in restoring or inducing an adequate immune response to reduce parasitic burden, leading to clinical improvement. This review focuses on immunotherapy directed at dogs infected by L. infantum, including a literature review of what has already been done in dogs. We also introduce a promising strategy to improve the efficacy of immunotherapy.

Canine visceral leishmaniasis biomarkers and their employment in vaccines

The natural history of canine visceral leishmaniasis (CVL) has been well described, particularly with respect to the parasite load in different tissues and immunopathological changes according to the progression of clinical forms. The biomarkers evaluated in these studies provide support for the improvement of the tools used in developing vaccines against CVL. Thus, we describe the major studies using the dog model that supplies the rationale for including different biomarkers (tissue parasitism, histopathology, hematological changes, leucocytes immunophenotyping, cytokines patterns, and in vitroco-culture systems using purified T-cells subsets and macrophages infected with L. infantum) for immunogenicity and protection evaluations in phases I and II applied to pre-clinical and clinical vaccine trials against CVL. The search for biomarkers related to resistance or susceptibility has revealed a mixed cytokine profile with a prominent proinflammatory immune response as relevant for Leishmania replication at low levels as observed in asymptomatic dogs (highlighted by high levels of IFN-γ and TNF-α and decreased levels in IL-4, TGF-β and IL-10). Furthermore, increased levels in CD4⁺ and CD8⁺ T-cell subsets, presenting intracytoplasmic proinflammatory cytokine balance, have been associated with a resistance profile against CVL. In contrast, a polyclonal B-cell expansion towards plasma cell differentiation contributes to high antibody production, which is the hallmark of symptomatic dogs associated with high susceptibility in CVL. Finally, the different studies used to analyze biomarkers have been incorporated into vaccine immunogenicity and protection evaluations. Those biomarkers identified as resistance or susceptibility markers in CVL have been used to evaluate the vaccine performance against L. infantum in a kennel trial conducted before the field trial in an area known to be endemic for visceral leishmaniasis. This rationale has been a guiding force in the testing and selection of the best vaccine candidates against CVL and provides a way for the veterinary industry to register commercial immunobiological products.

Multicomponent LBSap vaccine displays immunological and parasitological profiles similar to those of Leish-Tec® and Leishmune® vaccines against visceral leishmaniasis

Background

In past years, many researchers have sought canine visceral leishmaniasis (CVL) prevention through the characterization of Leishmania antigens as vaccine candidates. Despite these efforts, there is still no efficient vaccine for CVL control.

Methods

In the present study, we performed a pre-clinical vaccine trial using BALB/c mice to compare the effects of the multicomponent LBSap vaccine with those of Leish-Tec® and Leishmune®. Blood was collected to determine the frequency of peripheral blood cells and to evaluate hematologic and immunophenotypic parameters. Liver and spleen samples were collected for parasitological quantification, and spleen samples were used to access the cytokine profile.

Results

When measuring total IgG and IgG1 anti-Leishmania levels after the third vaccination and L. infantum challenge, it was evident that all vaccines were able to induce humoral immune response. Regarding the innate immune response, increased levels of NK CD3^-CD49⁺ cells were the hallmark of all vaccinated groups, whereas only the Leish-Tec® group displayed a high frequency of CD14⁺ monocytes after L. infantum challenge. Moreover, CD3⁺CD4⁺ T cells were the main circulating lymphocytes induced after L. infantum challenge with all evaluated vaccines. Importantly, after L. infantum challenge, splenocytes from the Leishmune® vaccine produced high levels of IL-2, whereas a prominent type 1 immune response was the hallmark of the LBSap vaccine, which presented high levels of IL-2, IL-6, TNF-α, and IFN-γ. The efficacy analysis using real-time polymerase chain reaction demonstrated a reduction in the parasitism in the spleen (Leishmune®: 64 %; LBSap: 42 %; and Leish-Tec®: 36 %) and liver (Leishmune®: 71 %; LBSap: 62 %; and Leish-Tec®: 48 %).

Conclusions

The dataset led to the conclusion that the LBSap vaccination was able to induce immune and efficacy profiles comparable with those of commercial vaccines, thus demonstrating its potential as a promising vaccine candidate for visceral leishmaniasis control.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1752-6) contains supplementary material, which is available to authorized users.

Impact of LbSapSal Vaccine in Canine Immunological and Parasitological Features before and after Leishmania chagasi-Challenge

Dogs represent the most important domestic reservoir of L. chagasi (syn. L. infantum). A vaccine against canine visceral leishmaniasis (CVL) would be an important tool for decreasing the anxiety related to possible L. chagasi infection and for controlling human visceral leishmaniasis (VL). Because the sand fly salivary proteins are potent immunogens obligatorily co-deposited during transmission of Leishmania parasites, their inclusion in an anti-Leishmania vaccine has been investigated in past decades. We investigated the immunogenicity of the "LbSapSal" vaccine (L. braziliensis antigens, saponin as adjuvant, and Lutzomyia longipalpis salivary gland extract) in dogs at baseline (T0), during the post-vaccination protocol (T3rd) and after early (T90) and late (T885) times following L. chagasi-challenge. Our major data indicated that immunization with "LbSapSal" is able to induce biomarkers characterized by enhanced amounts of type I (tumor necrosis factor [TNF]-α, interleukin [IL]-12, interferon [IFN]-γ) cytokines and reduction in type II cytokines (IL-4 and TGF-β), even after experimental challenge. The establishment of a prominent pro-inflammatory immune response after "LbSapSal" immunization supported the increased levels of nitric oxide production, favoring a reduction in spleen parasitism (78.9%) and indicating long-lasting protection against L. chagasi infection. In conclusion, these results confirmed the hypothesis that the "LbSapSal" vaccination is a potential tool to control the Leishmania chagasi infection.

Setting the proportion of CD4+ and CD8+ T-cells co-cultured with canine macrophages infected with Leishmania chagasi

New methods for evaluating the canine immune system are necessary, not only to monitor immunological disorders, but also to provide insights for vaccine evaluations and therapeutic interventions, reducing the costs of assays using dog models, and provide a more rational way for analyzing the canine immune response. The present study intended to establish an in vitro toll to assess the parasitological/immunological status of dogs, applicable in pre-clinical trials of vaccinology, prognosis follow-up and therapeutics analysis of canine visceral leishmaniasis. We have evaluated the performance of co-culture systems of canine Leishmania chagasi–infected macrophages with different cell ratios of total lymphocytes or purified CD4⁺ and CD8⁺ T-cells. Peripheral blood mononuclear cells from uninfected dogs were used for the system set up. Employing the co-culture systems of L. chagasi–infected macrophages and purified CD4⁺ or CD8⁺ T-cell subsets we observed a microenvironment compatible with the expected status of the analyzed dogs. In this context, it was clearly demonstrated that, at this selected T-cell:target ratio, the adaptive immune response of uninfected dogs, composed by L. chagasi-unprimed T-cells was not able to perform the in vitro killing of L. chagasi–infected macrophages. Our data demonstrated that the co-culture system with T-cells from uninfected dogs at 1:5 and 1:2 ratio did not control the infection, yielding to patent in vitro parasitism (≥80%), low NO production (≤5 μM) and IL-10 modulated (IFN-γ/IL-10≤2) immunological profile in vitro. CD4⁺ or CD8⁺ T-cells at 1:5 or 1:2 ratio to L. chagasi–infected macrophages seems to be ideal for in vitro assays. This co-culture system may have great potential as a canine immunological analysis method, as well as in vaccine evaluations, prognosis follow-up and therapeutic interventions.

Cytokine and nitric oxide patterns in dogs immunized with LBSap vaccine, before and after experimental challenge with Leishmania chagasi plus saliva of Lutzomyia longipalpis

In the studies presented here, dogs were vaccinated against Leishmania (Leishmania) chagasi challenge infection using a preparation of Leishmania braziliensis promastigote proteins and saponin as adjuvant (LBSap). Vaccination with LBSap induced a prominent type 1 immune response that was characterized by increased levels of interleukin (IL-) 12 and interferon gamma (IFN-γ) production by peripheral blood mononuclear cells (PBMC) upon stimulation with soluble vaccine antigen. Importantly, results showed that this type of responsiveness was sustained after challenge infection; at day 90 and 885 after L. chagasi challenge infection, PBMCs from LBSap vaccinated dogs produced more IL-12, IFN-γ and concomitant nitric oxide (NO) when stimulated with Leishmania antigens as compared to PBMCs from respective control groups (saponin, LB- treated, or non-treated control dogs). Moreover, transforming growth factor (TGF)-β decreased in the supernatant of SLcA-stimulated PBMCs in the LBSap group at 90 days. Bone marrow parasitological analysis revealed decreased frequency of parasitism in the presence of vaccine antigen. It is concluded that vaccination of dogs with LBSap vaccine induced a long-lasting type 1 immune response against L. chagasi challenge infection.

Analysis using canine peripheral blood for establishing in vitro conditions for monocyte differentiation into macrophages for Leishmania chagasi infection and T-cell subset purification

Canine visceral leishmaniasis (CVL) is a parasitic disease endemic in many countries, and dogs present as the major natural reservoir of the parasite, Leishmania chagasi (syn. L. infantum). Biomarkers in the canine immune system is an important technique in the course of developing vaccines and treatment strategies against CVL. New methodologies for studying the immune response of dogs during Leishmania infection and after receiving vaccines and treatments against CVL would be useful. In this context, we used peripheral blood mononuclear cells (PBMCs) from healthy dogs to evaluate procedures related to (i) establishment of in vitro conditions of monocytes differentiated into macrophages infected with L. chagasi and (ii) purification procedures of T-cell subsets (CD4⁺ and CD8⁺) using microbeads. Our data demonstrated that after 5 days of differentiation, macrophages were able to induce significant phagocytic and microbicidal activity after L. chagasi infection and also showed increased frequency of parasitism and a higher parasite load. Although N-acetyl-β-d-glucosaminidase (NAG) levels presented similar levels of macrophage culture and L. chagasi infection, a progressive decrease in myeloperoxidase (MPO) levels was a hallmark over 5 days of culture. High purity levels (>90%) of CD4 and CD8 T cells were obtained on a magnetic separation column. We concluded that monocytes differentiated into macrophages at 5 days and displayed an intermediate frequency of parasitism and parasite load 72 h after L. chagasi infection. Furthermore, the purification system using canine T-lymphocyte subsets obtained after 5 days of monocyte differentiation proved efficient for CD4 or CD8 T-cell purification (≥90%). The in vitro analysis using L. chagasi-infected macrophages and purified T cells presented a prospective methodology that could be incorporated in CVL vaccine and treatment studies that aim to analyze the microbicidal potential induced by specific CD4⁺ and/or CD8⁺ T cells.

The natural history of carpal tunnel syndrome. A study of 20 hands evaluated 4 to 9 years after initial diagnosis

Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy. In the last decade several papers have been published on epidemiology, clinical aspects, diagnosis, and treatment, but little is known about its natural history. The objective of this work was to study the natural history of CTS syndrome. From 358 patients with clinical and conduction study diagnosis of CTS, 12 cases were identified that had refused surgical treatment, had not used anti-inflammatory medications, and had not undergone orthopaedic procedures, such as immobilization or anaesthetic infiltration. These 12 patients have 20 compromised hands which have been followed up for between 4 and 9 years. In all cases sensory and motor conduction studies were performed on the median nerve, at the beginning and end of follow-up period. Electrical improvement was marked in 5 hands and slight in 3; there was no significant change in 10, and deterioration in 2. As 8 hands (7 patients) showed improved clinical symptoms and conduction studies over several years, this brings the universally accepted procedure of surgical treatment into doubt.

Effects of ethanol on human visual evoked potentials

Studies of the effect of ethanol on human visual evoked potentials are rare and usually involve chronic alcoholic patients. The effect of acute ethanol ingestion has seldom been investigated. We have studied the effect of acute alcoholic poisoning on pattern-reversal visual evoked potentials (PR-VEP) and flash light visual evoked potentials (F-VEP) in 20 normal volunteers. We observed different effects with ethanol: statistically significant prolonged latencies of F-VEP after ingestion, and no significant differences in the latencies of the PR-VEP components. We hypothesize a selective ethanol effect on the afferent transmission of rods, mainly dependent on GABA and glutamatergic neurotransmission, influencing F-VEP latencies, and no effect on cone afferent transmission, as alcohol doesn't influence PR-VEP latencies.

Morphological aspects of rabbit masseter muscle after cervical sympathectomy

The objective of this paper was to study the effect of sympathetic innervation on morphological and histochemical aspects of skeletal muscle tissue. Rabbit masseter muscle was studied using histochemical and immunohistochemical methods for periods of up to 18 months post-sympathectomy. The morphological and enzymatic characteristics of control masseter muscles were similar on both the left and right sides. The main features were muscle fibres with a mosaic pattern and a predominance of type IIa fibres, followed by type I. Type IIb fibres showed very low frequency. Sympathectomized animals showed varying degrees of metabolic and morphological alterations, especially 18 months after sympathectomy. The first five groups showed a higher frequency of type I fibres, whilst the oldest group showed a higher frequency of type IIb fibres. In the oldest group, a significant variation in fibre diameter was observed. Many fibres showed small diameter, atrophy, hypertrophy, splitting, and necrosis. Areas with fibrosis were observed. Thus cervical sympathectomy induced morphological alterations in the masseter muscles. These alterations were, in part, similar to both denervation and myopathy. These findings indicate that sympathetic innervation contributes to the maintenance of the morphological and metabolic features of masseter muscle fibres.

Multimodal evoked potentials and the ovarian cycle in young ovulating women

There is controversy over how hormonal conditions influence cerebral physiology. We studied pattern-shift visual evoked potentials (PS-VEP), brain stem auditory evoked potentials (BAEP) and short-latency somatosensory evoked potentials (SSEV) in 20 female volunteers at different phases of the menstrual cycle (estrogen phase, ovulatory day and progesterone phase). Statistical analysis showed decreased latencies for P100 (PS-VEP), N19 and P22 (SSEV) waves in the progesterone phase compared with the estrogen phase. There was no significant difference between the estrogen and the ovulation day values. Comparing the three above stages, there were no significant differences in the brainstem auditory evoked potentials. The reduction of the latencies of the potentials generated in multisynaptic circuits provides the first consistent neurophysiological basis for a tentative comprehension of human pre-menstrual syndrome.

Ulnar-to-median nerve anastomosis in the forearm. Review and report of 2 new cases

The ulnar-to-median nerve anastomosis in the forearm is a very rare occurrence, not mentioned in many anatomical text books. We found only 4 cases cited in medical literature. Here we describe 2 new cases, for which diagnosis was suspected when the compound muscle action potential of the abductor pollicis brevis muscle (APB), obtained by maximal stimulation of the median nerve at the elbow, was lower than that obtained at the wrist. The diagnosis was confirmed by stimulation of the ulnar nerve at the elbow, which evoked a compound muscle action potential of the APB with a clear negative initial deflection without volume-conducted potential.

Test of a new technique for the diagnosis of carpal tunnel syndrome

Several new techniques for carpal tunnel syndrome diagnosis have been developed in the last few years. This work tests a technique that compares the distal motor latency of the median nerve to the second lumbrical muscle (2L) with the distal motor latency of the ulnar nerve to the interossei muscle (INT). Results from 40 normal hands give the superior limit of the normal difference (2L-INT) as 0. 26 ms (&xmacr;+3 SD). In 55 hands with different levels of carpal tunnel syndrome, this new technique was more sensitive and accurate than the conventional test which uses the distal motor latency of the median nerve to the abductor pollicis brevis muscle (APB), especially in the less severe cases. With the absence of the compound muscle action potentials of the APB muscle caused by severe thenar atrophy, it is much easier to obtain the potential from the 2L muscle. We concluded that this is a sensitive, simple, rapid, and non-invasive new technique, and therefore, it should be incorporated as part of the routine ENMG procedures for carpal tunnel syndrome diagnosis.

Silent period in carpal tunnel syndrome

The silent period is a misunderstood electrophysiological phenomenon leading to several different hypotheses explaining its electrogenesis. It has been studied by different authors and different methodologies giving a wide variability of results, therefore an exact pattern of its normal values does not exist. This work was undertaken to define the normal morphology and duration of the silent period obtained by supramaximal stimulus of the median nerve, during maximum isometric effort of the abductor pollicis brevis muscle against resistance, using 20 adult volunteers without neurological alterations. The normal median duration was 104.6 milliseconds. The same methodology was applied to 20 hands from 20 patients with carpal tunnel syndrome. The silent period showed many types of morphological alterations, but the major alteration observed was a tendency to temporal elongation. No correlation between the severity of the carpal tunnel syndrome and the silent period alterations were observed.

Electromyographic analysis of the superior belly of the omohyoid muscle and anterior belly of the digastric muscle in tongue and head movements

The participation of the superior belly of the omohyoid muscle and anterior belly of the digastric muscle in tongue and head movements was studied eletromyographically in 20 normal young volunteers. A pair of monopolar electrodes was used in each muscle for simultaneous recording of their actions. The muscles act in the following tongue movements: protrusion, right and left lateral movements, placement of the tip of the tongue on soft and hard palates and on the floor of the mouth. The strongest levels of activity of the superior belly of the omohyoid muscle were observed in the placement of the tip of the tongue on the soft palate, coincidentally with a greater dislocation of hyoid bone. Both of the muscles studied did not participate in the head's kinesiology.

Electromyographic analysis of superior belly of the omohyoid muscle and anterior belly of the digastric muscle in mandibular movements

The superior belly of the omohyoid muscle and the anterior belly of the digastric muscle, were studied electromyographically in 20 young volunteers. For each muscle, 1 pair of monopolar electrodes was employed. One was a surface electrode and the other a needle electrode, which was inserted in the belly of the muscle. The surface electrode was placed 1 cm apart from the needle electrode. The most marked action of both muscles was on the movement of lowering the mandible. They also act in those movements for the performance of which they have associated a component of lowering the jaw, propulsion, laterality to the right and the left and retrusion. They are not active in the resting position and during jaw movements of elevation, extrusion and protrusion. Both muscles are active most of the time, simultaneously, but it is not possible to demonstrate that there is a synchronism between their actions.

Reconsiderations about the clinical importance of the sympathetic skin response

Over the last few years, neurologists have been showing increasing interest in the study of the sympathetic skin response (SSR). In the present report we describe a simple method that permitted us to determine a wide variation of SSR in response to different stimuli such as respiration, deglutition, blinking, skeletal movements, biting, auditory or light stimuli, vocalization, and sphincter contraction. These results raise doubts about the role of SSR as a complementary diagnostic method.

[Evoked potentials in neurocysticercosis]

In 25 patients with cysticercosis of central nervous system, classified in two clinical forms, benign and malign, evoked potentials were obtained. Normal exam was found in 9 cases with the benign form. From 4 patients with malign clinical presentations, 2 had multiple abnormalities of the evoked potentials, and F wave alterations (mixed pattern). The authors suggest that this mixed pattern may be indicative of severe prognosis.

Compression of the peripheral branches of the sciatic nerve by lipoma

The authors report two female patients with chronic sensitive and motor findings in lower limbs caused by compression of distal branches of sciatic nerve by lipoma. Similar cases were not described on literature. Nerve conduction studies allowed to localize the exact site of compression. At surgery, lipomas compressing the deep peroneal nerve (case 1) and the posterior tibial nerve (case 2) were observed. Histologic studies of tumors confirmed the diagnoses.

[Neuromuscular action of crotalid venoms: preliminary data]

We studied 6 patients and 2 dogs that have been bitten by South American rattlesnake Crotalus durissus terrificus and one rabbit inoculated with crotalid venom. We analyzed sensory and motor peripheral nerve conduction, repetitive stimulation for studying neuromuscular transmission and electromyographies. Muscle biopsies were processed by histochemistry. All patients had peripheral mononeuropathy of the closest sensitive nerve to the area of snakebite. The neuromuscular transmission alterations were minimal. Muscle histochemistry of 4 patients, 2 dogs and 1 rabbit showed findings of mitochondrial myopathy. The majority of authors admit that crotalid venom causes myastenic syndrome. Our findings suggest that palpebral ptosis, myastenic facies and muscular weakness observed after crotalid poisoning are, probably, due to transient and reversible mitochondrial myopathy. As far as we know, this is the first report on the ability of the venom of this rattlesnake to cause local sensitive mononeuropathy and the first muscle histochemistry showing mitochondrial myopathy in humans poisoned by crotalid venom.

Chronic motor neuron disease possibly related to intoxication with organochlorine insecticides

We report on two patients with a history of chronic exposure to organochlorine insecticides who developed clinical and electromyographic signs and symptoms of chronic motor neuron disease. Measurements of aldrin, lindane and heptachlor confirmed the intoxication. We emphasize the importance of searching for toxic and environmental factors in cases of motor neuron disease especially in Third World countries, where workers usually wear no adequate protective equipment.

[Focal epileptic activity during induced sleep in secondary Lennox-Gastaut syndrome]

Fifteen patients with secondary Lennox-Gastaut syndrome were submitted to monthly clinical and electroencephalographic examinations for periods of time varying from 1 to 9 years. Twelve of these patients showed focal epileptic activity during induced sleep. In the present report we describe the localization, morphology and frequency of these focal discharges.

[Electroencephalogram before and after hemodialysis, peritoneal dialysis and renal transplantation: study of correlations between background activity and plasma biochemistry]

We report disorganization of background activity in the EEG of 49 patients with chronic renal failure. An electroencephalographic and biochemical study was performed in 20 patients before and after dialysis sessions. We did the same study before and after peritoneal dialysis in 14 patients. We analysed the EEG compared to biochemical blood abnormalities before and after renal transplantation in 15 patients. We observed worsening of the EEG after hemodialysis and peritoneal dialysis and improvement after renal transplantation, suggesting that in our patients the abnormalities in EEG caused by chronic renal failure were reversible. From our results, we found it difficult to establish correlations between the EEG and the biochemical blood abnormalities. However, there is statistical correlation between hypernatremia, improvement of metabolic acidosis, increase of the ratio of zinc to copper and worsening of the background activity in EEG.

[Hepatic encephalopathy: study of 50 cases]

The authors present a retrospective study of 50 patients with hepatic encephalopathy treated at the University Hospital, Faculty of Medicine of Ribeirão Preto since 1959 and discuss clinical, laboratory and anatomo-pathologic aspects. The diagnoses of the different types of liver disease as well as the factors that triggered the episodes of hepatic coma and pre-coma are reported and the role of the measurement of arterial blood gases in establishing the diagnosis is emphasized.

[Marfan syndrome and giant intracranial aneurysms: report of a case]

Os autores relatam um caso de síndrome de Marfan com aneurismas intracranianos gigantes, em paciente do sexo feminino, de 54 anos de idade.

[Progressive facial hemiatrophy: report of a case]

The authors report a case of Parry-Romberg disease with predominantly facial left atrophy, seizures, amnesic aphasia, mental retardation, right hemiplegia and hemianesthesia, and cerebellar syndrome. The rarity of cerebellar atrophy (only one case thus far reported in the literature surveyed) is emphasized, as well as the correlation between the clinical abnormalities and the computerized axial tomography of the skull.

[Miller Fisher syndrome: report of a case]

The authors report a case of a 27 year old male patient who has exhibited external ophthalmoplegia, anisocoria, ataxia, absent deep reflexes, dysphagia, dysphonia, bilateral peripheral facial paralysis, hypopallesthesia and a mild sensory impairment of the four extremities. In addition, his cerebrospinal fluid showed albuminocytologic dissociation. The otoneurologic examination showed important findings. These symptoms began ten days after a "cold", and quickly subsided after prednisone therapy. Two months after the onset of clinical features, just a deep apendicular areflexia was detected on his neurological examination. The neurological signs and complementary laboratory findings suggest that both central and peripheral alterations are responsible for the clinical manifestations.