Chronic malnutrition caused by a corn-based diet lowers the threshold for pentylenetetrazol-induced seizures in rats

The incidence of epilepsy is high in developing countries where malnutrition is prevalent. Although malnutrition is not a direct cause of seizures, chronic malnutrition may predispose the brain to seizures. In large undernourished human groups from Latin America, the most common sources of food are corn and corn derivatives. We used a rat model of chronic malnutrition, in which corn tortillas were the only solid food intake, to study the possible influence of malnutrition at late stages of brain development on the dynamics of experimental seizures induced by pentylenetetrazole (PTZ). The threshold and does of PTZ required to produce seizures were greatly reduced in malnourished rats. The model of malnutrition used in the study imitates a form of malnutrition common among large numbers of humans. Our results suggest that chronic malnutrition early in life induces changes that lower the seizure threshold and leave the brain more susceptible to seizures. Whether this observation relates to the high incidence of epilepsy in underdeveloped countries remains to be determined.

Effects of pentoxifylline or dexamethasone in combination with amphotericin B in experimental murine cerebral cryptococcosis: evidence of neuroexcitatory pathogenic mechanisms

In a murine model of intracerebral infection by Cryptococcus neoformans the therapeutic effects of pentoxifylline or dexamethasone were studied alone and in combination with amphotericin B. Assessed parameters were mean survival time, brain histopathology index, amounts of glutamate and gamma-aminobutyric acid in the brain, and yeast CFU per brain. Survival increased significantly in mice treated with dexamethasone, amphotericin B, amphotericin B plus dexamethasone, and amphotericin B plus pentoxifylline; the latter had significantly longer survival than other treated groups. Indices of histopathological damage were similar in all treated groups. In infected untreated mice, the amounts of glutamate in the brain were decreased, presumably by depletion. In mice treated with amphotericin B plus dexamethasone, glutamate levels returned to the range of control mice. No differences in the amounts of gamma-aminobutyric acid were found between control and treatment groups. Brain fungal counts were significantly lower in mice treated with amphotericin B, amphotericin B plus dexamethasone, and amphotericin B plus pentoxifylline than in untreated animals. In this model, pentoxifylline in combination with amphotericin B improved survival, decreasing the fungal burden, and has potential as adjuvant therapy in cerebral cryptococcosis.

Cryptococcus neoformans var. gattii among patients with cryptococcal meningitis in Mexico. First observations

A retrospective study of 20 patients with cryptococcal meningitis and their isolated strains was performed. Cryptococcus neoformans var. neoformans was recovered from 14 (70%) cases, and var. gattii was recovered from six (30%) patients. Twelve patients had AIDS (all carrying var. neoformans), two had other diseases (one with var. neoformans and one var. gattii) and there was no identifiable underlying disease in six (one var. neoformans and five var. gattii). Fourteen patients (11 var. neoformans and three var. gattii) resided in the Mexico City area, where a temperate climate is prevalent, and there were six cases (three var. neoformans and three var. gattii) from states with a tropical/subtropical climate. Although there was no significant statistical difference between the two varieties, the fatal outcome was higher in patients with var. neoformans. The disease caused by var. gattii strains was characterized by a higher opening pressure, more inflamatory changes of CSF and a longer clinical course (delayed clinical and mycological cure). Cryptococcus neoformans var. gattii is a significant cause of cryptococcal meningitis in patients without underlying diseases in Mexico.

Colchicine decreases the infection by Toxoplasma gondii in cultured glial cells

Addition of colchicine (2.5 x 10(-8)-1.25 x 10(-6) M) to cultures of glial cells infected with Toxoplasma gondii decreased the number of parasites up to 80% (P < 0.05) in comparison with controls. Our results indicate that colchicine could interfere with the infectious, or replicative mechanisms, or both, of Toxoplasma and place it as a candidate in the search for additional antitoxoplasmic therapy for those cases where the parasitic load is massive. Further studies in vivo must be made to confirm this finding and provide support for therapeutic trials.

Effects of prednisone on ventriculoperitoneal shunt function in hydrocephalus secondary to cysticercosis: a preliminary study

In a prospective open study, 15 patients with hydrocephalus secondary to cysticercosis who required insertion of a ventriculoperitoneal (VP) shunt were treated with 50 mg of prednisone given orally three times a week. Treatment began in the 1st postoperative week, with isoniazid and pyridoxine administered daily as antituberculous chemoprophylaxis. The drug regimen was continued with close follow up for 24 months. Clinical status, Karnofsky performance status (KPS) scores, and postoperative course in the prednisone-treated group were compared with 30 control patients with hydrocephalus due to cysticercosis. The control patients were matched by age and sex, underwent surgical shunting in the same period, and were followed routinely by the neurosurgery staff. Lumbar cerebrospinal fluid (CSF) was studied in 2, 16, and 32 weeks postoperatively in the prednisone group. At 24-month follow up two (13%) of 15 patients in the prednisone group and 19 (60%) of 30 patients in the control group required surgical shunt revisions for symptomatic shunt obstruction (p=0.002). Follow-up studies of CSF performed at 32 weeks in the prednisone group revealed improvement of abnormal values with statistically significant differences for glucose (p<0.02). Serial imaging studies in the prednisone group revealed persistence of cysticercal cysts with no change in size. Mean initial KPS scores were similar in both groups. At the end of the follow-up period, the mean KPS score was significantly higher in the prednisone group (p=0.003). Prednisone and chemoprophylactic drugs were well tolerated. These results suggest that in selected patients with hydrocephalus secondary to cysticercosis, intermittent long-term prednisone therapy after VP shunting may reduce shunt malfunction and improve the functional status of the patients.

Immunodominant synthetic peptides of Taenia crassiceps in murine and human cysticercosis

The screening of a cDNA library of Taenia crassiceps revealed a clone designated KETc7 that induced high levels of protection against murine cysticercosis in previous experiments. The molecular structure of the deduced 100-amino acid sequence of the corresponding proline-rich polypeptide was studied to detect potentially immunologically active epitopes. Several candidate epitopes were identified, three of which were synthesized by solid-phase peptide synthesis and used as antigens in enzyme-linked immunosorbent assay (ELISA) for detection of specific antibodies in a selected panel of sera from mice infected with Taenia crassiceps and pigs infected with Taenia solium, as well as in the serum and cerebrospinal fluid of human patients with neurocysticercosis. The three peptides detected antibodies in serum from all infected mice. Seven of nine sera from patients with neurocysticercosis reacted strongly with peptide GK-3, and four of them with peptides GK-1 and GK-2. A lower reactivity was observed in sera from experimentally infected pigs. Peptide GK-3 reacted also with 45 out of 77 cerebrospinal fluids (CSF) from patients with confirmed neurocysticercosis and with 14 out of 68 CSF from control patients with other neurological disorders. This is the first report on synthetic peptides that are prominent in the humoral response of murine, porcine and human cysticercosis. Their identification implies finer molecular tools in the exploration of this form of host-parasite relationship, as well as hints to their application in immunodiagnosis and in vaccine design.

Increase in the lumen of the femoral artery in dogs with an arteriotomy encircled by glutaraldehyde-tanned calf pericardium

A fast and simple experimental method of arterioplasty that produces enduring enlargement of the lumen of large arteries is described. We studied the long-term intraluminal patency of femoral arteries of four dogs subjected to a procedure in which a longitudinal 3-cm loophole was made in the artery and left open inside a girdling cylinder of glutaraldehyde-tanned calf pericardium. One year later, Doppler ultrasound and histological studies were performed in the operated and contralateral arteries. Lasting enlargement of the lumen was obtained along the 3-cm arteriotomy. The mean cross-sectional internal diameter in the middle of the surgical area was 2.2 +/- 0.1 mm, in contrast to 1.2 +/- 0.2 mm in the non-operated contralateral artery (P < 0.01). The ultrasound study showed an increase in blood flow and histological analysis demonstrated a threefold increase in the internal area of the arterial lumen, and new endothelium, which fully covered the operated segment. Our results showed an enduring increase in the lumen in segments of large arteries subjected to our new arterioplasty procedure.

Antigens from Taenia crassiceps cysticerci used in complement fixation, enzyme-linked immunosorbent assay, and western blot (immunoblot) for diagnosis of neurocysticercosis

Antigens from Taenia solium cysticerci for the immunodiagnosis of cysticercosis are scarce and difficult to obtain. We studied the reliability of antigens from Taenia crassiceps cysticerci as a substitute for those from T. solium in three diagnostic tests: complement fixation, enzyme-linked immunosorbent assay, and Western blot (immunoblot). Precision rates of the three tests of 93, 99, and 96%, respectively, were found. Cysticerci from T. crassiceps can be easily obtained in large quantities and can be effectively used for the diagnosis of human neurocysticercosis.

Is the frequency of multiple sclerosis increasing in Mexico?

Multiple sclerosis has steadily increased in Mexican mestizos from an apparently rare disorder in the 1970s to the second most frequent cause of admission to a neurology ward in the 1990s. Most patients belonged to high socioeconomic and educational groups. Familial incidence was low. Age at onset was younger than in other series and long term disability was milder than in patients from countries in which the disease is apparently more prevalent.

Differences between ventricular and lumbar cerebrospinal fluid in hydrocephalus secondary to cysticercosis

We studied ventricular and lumbar cerebrospinal fluid (CSF) in 16 patients with hydrocephalus secondary to meningeal cysticercosis, and samples were taken at the time of the surgical implantation of a ventricular shunt. All lumbar CSF samples revealed raised cell counts (mean, 72 +/- 28/mm3) and protein counts (mean, 78 +/- 12 mg/dl), as well as positive immune reactions to cysticerci antigens. In contrast, 50% of the ventricular CSF samples exhibited cell and protein counts within normal limits and five showed negative immune reactions to cysticerci antigens. Ample differences between ventricular and lumbar CSF were also observed in the contents of glucose and immunoglobulins G, A, and M. The biochemical and immunological composition of the CSF varied greatly along the cerebrospinal axis in patients with chronic arachnoiditis caused by cysticercosis. Our findings further support the premise of the subarachnoid space as an immunologically active substratum and provide information to explain the frequent occlusion of ventricular shunts in patients with hydrocephalus secondary to inflammatory disorders of the subarachnoid space.

Changes in brain, plasma and cerebrospinal fluid contents of beta-endorphin in dogs at the moment of death

To investigate the possible participation of endogenous opioids in the cerebral events that take place at the moment of death we studied brain, cerebrospinal fluid and serum contents of beta-endorphin in dogs that were either conscious or unconscious at the moment of sudden death induced by cardiac arrest. Although with great interindividual variations, the animals that were conscious at the moment of cardiac arrest, presented a significant increase in beta-endorphin when compared with their own previous values (p < 0.05) or with the values found in animals that were deeply anaesthetized at the time of cardiac arrest. There seems to be a sudden increment of beta-endorphin in brain tissue and body fluids of dogs who are conscious at the moment of sudden death, this change was not observed in dogs that were anaesthetized prior to death. Brain opioids could participate in the sensations narrated by subjects in the so called near-death experience.

A new shunt for hydrocephalus that relies on CSF production rather than on ventricular pressure: initial clinical experiences

BACKGROUND

Ventricular shunting for hydrocephalus is one of the surgical procedures most frequently associated with complications. When the hydrocephalus is secondary to arachnoiditis the prognosis is usually poor.

METHODS

Twenty-six patients with hydrocephalus secondary to chronic arachnoiditis due to meningeal cysticercosis were treated with a new ventriculoperitoneal shunt whose design is based on the rate of cerebrospinal fluid (CSF) production and shunt resistance rather than on ventricular pressure, which has been the principal parameter for most other shunting devices.

RESULTS

The shunt has remained functional in 25 patients (96%). A peculiar response was documented in all cases by sequential CT scans; i.e.; the size of the ventricular cavities showed gradual reduction and about 1 month postsurgery the ventricles had returned to normal size. In all cases, fast clinical improvement was documented within the first 2 days after surgery with remission of all symptoms of intracranial hypertension. Improvement has continued for a mean follow-up of 9 +/- 2 months. In one case, the shunt was occluded a month after surgery, was withdrawn, and was replaced by a conventional shunt.

CONCLUSIONS

Our initial results contrast with the experience with other shunts, which in these patients have a rate of 50% occlusion within the first 4 months after surgery. Although a long-term follow-up is mandatory, it seems that the treatment of hydrocephalus by a shunt devoid of valve mechanisms, with drainage capacity limited to physiological parameters of CSF production, could avoid the unacceptable high frequency of overdrainage and occlusion that are the main complications of shunting devices that operate in relation to ventricular pressure.

Diagnosis of American trypanosomiasis (Chagas' disease) by the new complement fixation test

A new immunodiagnostic method of complement fixation was used for serodiagnosis of American trypanosomiasis; 92% sensitivity and 99% specificity were obtained, for an overall accuracy of 97%. This test can be used in field studies, obviating the use of most laboratory equipment and imported reagents; places where economic limitations hinder the use of other immunodiagnostic procedures; and in association with other tests for confirmation of the diagnosis.

Reversibility of the alterations induced by chronic alcoholism and malnutrition in rats after alcohol withdrawal and proper nutrition

OBJECTIVE

The specific influence of malnutrition on the cellular damage induced by alcoholism has been poorly defined; therefore, the possible degree of improvement that could be obtained after the institution of proper nutrition and after alcohol withdrawal remains unclear. We studied both conditions in several combinations, either after chronic alcoholism, chronic malnutrition or both, and after reversal of each condition or of both.

METHOD

Using experimental models of alcoholism and malnutrition, we studied the alterations induced by each condition and on the combination of both in five histological locations and in 10 hematological and biochemical parameters; afterwards, we studied the possible restorative effect on each parameter after 4 months of alcohol withdrawal or proper nutrition or both.

RESULTS

Our results showed that chronic alcoholism induced a mean of 31% deviation from values obtained in controls, malnutrition induced 17%, and alcoholism and malnutrition combined induced 52%. Upon the removal of the offending condition, alcohol withdrawal brought 13% improvement and proper nutrition 5% improvement; in the animals with alcoholism and malnutrition, alcohol withdrawal and proper nutrition brought 26% improvement, alcohol withdrawal but continuation of malnutrition 10% improvement, and continuation of alcoholism but proper nutrition led to a further 8% worsening from the alterations already found during alcoholism and malnutrition.

CONCLUSIONS

Multivariate statistical comparisons demonstrated that chronic malnutrition produced an important, independent and difficult to reverse effect on the damage induced by alcoholism in several histological and physiological parameters.

Dengue virus infects mouse cultured neurons but not astrocytes

Cultures of mouse brain cells containing a high proportion either neurons or astrocytes were inoculated with various strains of dengue virus. At analysis by double immunofluorescence, all strains of dengue virus studied were tropic for neurons. In no case were the astrocytes infected. Only approximately 10% of all neurons were infected, suggesting that the virus may enter the cell through a membrane receptor present only in a subgroup of neurons.

Low contents of nerve growth factor in serum and submaxillary gland of diabetic mice. A possible etiological element of diabetic neuropathy

Insulin and nerve growth factor are peptides that share several chemical and functional properties. While the total or relative deficiency of insulin causes diabetes, the possible disorders due to deficiency of nerve growth factor have not been clearly defined. However, the intense biological actions of nerve growth factor in the maintenance and growth of several neural cells make feasible its participation in the physiopathology of some diseases of the peripheral nervous system. We measured the contents of nerve growth factor in serum, submaxillary gland and sciatic nerve of mice with streptozotocin-induced diabetes. Nerve growth factor in diabetic mice was diminished in serum and submaxillary gland when compared with matched controls (P < 0.01). This finding further supports a similar observation in diabetic patients and suggests a possible etiological involvement of neural growth factor in the development of diabetic neuropathy.

Detrimental effects of malnutrition on the damage induced by alcoholism: a study of animal models that simulate chronic alcoholism and malnutrition of large human groups

The specific influence of malnutrition on the pathophysiological changes induced by chronic alcoholism is controversial; most studies are inconclusive because they have been made in chronic alcoholics that develop malnutrition as a complication of alcoholism. However, in vast human groups, alcoholism evolves in individuals that belong to a chronically undernourished population. In an attempt to simulate real-life conditions of malnutrition-alcoholism in humans, we studied in rats: (1) the effects of chronic malnutrition with tortilla, a corn bread that constitutes the main diet of large human groups; (2) the effects of chronic alcoholism with commercial brandy; and (3) the effects of chronic alcoholism and malnutrition combined. The damage induced either by alcoholism or that induced by malnutrition alone were of similar degree, whereas the combination of malnutrition and alcoholism led to a worsening of some parameters studied: body weight, leucocyte count and, more remarkably, in the tissue damage of several areas of the central nervous system.

Effect of anticysticercal treatment on the prognosis of epilepsy in neurocysticercosis: a pilot trial

Epilepsy secondary to active or inactive neurocysticercosis (NCC) is a major public health problem in Latin American countries. In an open-label pilot trial, we evaluated and followed (mean = 13 months) 16 patients with epilepsy resulting from active NCC which was treated with anticisticercal (ACC) drugs. These patients were aged 12-68 years with confirmed active NCC and seizures not controlled by adequate antiepileptic drug (AED) therapy. Patients were treated with albendazole or praziquantel (ALB and PZQ, ACC drugs) and AED monotherapy. The number of NCC cysts was markedly reduced by ACC therapy. Thirteen patients remained seizure-free and 2 had only one seizure during follow-up. Our data suggest a positive effect of ACC treatment on the prognosis of epilepsy caused by active NCC, but a prospective, double-blind, controlled study with long-term follow-up must be performed to determine whether ACC therapy improves long-term seizure control.

Therapy for neurocysticercosis: a reappraisal

Accepted approaches to therapy for the different forms of neurocysticercosis are reviewed. Therapy must be individualized according to the level of disease activity and the location of the parasite. Patients with inactive disease should receive only symptomatic treatment. In contrast, patients with parenchymal brain cysts must receive a course of anticysticercal drugs. Both albendazole and praziquantel are useful; however, recent evidence favors the former as the drug of choice for this form of the disease. Albendazole (but not praziquantel) is also effective in the treatment of giant subarachnoid cysts; such medical treatment obviates surgery in some cases. Patients with ventricular cysts may also benefit from medical therapy; however, surgery is the current approach to this type of lesion, as it is to spinal cysticercosis. Although intraocular cysts have classically been resected by surgery, a recent study indicates that albendazole is equally effective. For patients with mixed forms of neurocysticercosis, therapeutic measures related to--but not directly targeting--the disease (i.e., steroid administration for brain edema or shunt placement for hydrocephalus) should be contemplated before therapy with anticysticercal drugs is instituted.

Changes in the threshold of pentylenetetrazol-induced seizures in cats with a chronic granuloma in brain amygdala

A parenchymal brain granuloma is the final consequence of a localized inflammatory reaction against an infectious agent, particularly parasites. In humans, these lesions are frequent causes of epilepsy. We studied the pattern of seizures induced by pentylenetetrazol (PTZ) in cats with a chronic granuloma induced 1 year earlier by injection of silicates into the brain amygdala. Compared with controls, the seizure threshold to myoclonic seizures was significantly decreased in cats with granuloma, while the threshold for tonic-clonic seizures was not altered. Thus, the difference in PTZ doses between the initial and final components of the seizure became significantly enlarged (P < 0.001). Our results indicate that a granulomatous lesion in amygdala facilitates the generation and propagation of myoclonic seizures, whereas other components of PTZ-induced seizures are not affected.

Electroconvulsive shock does not modify striatal contents of dopamine in MPTP-treated mice

It has been suggested that the therapeutic response to electroconvulsive therapy in depressed patients could be mediated by functional changes in the dopaminergic pathways; a favorable response to electroconvulsive therapy was also observed recently in patients with Parkinson's disease. To study a possible interference of electroconvulsive shock in the course of MPTP-induced parkinsonism in rodents, we measured the striatal content of dopamine in MPTP-treated mice that received electroconvulsive shock at various intervals in the course of MPTP neurotoxicity. Our results showed no immediate or delayed differences in striatal dopamine content of animals that received MPTP and electroconvulsive shock when compared with animals that received only MPTP, thus suggesting that the strong biological effects of MPTP and electroconvulsive shock on the brain may follow different biochemical mechanisms.

Pharmacokinetic comparison of two albendazole dosage regimens in patients with neurocysticercosis

To evaluate two different dosage regimens for albendazole (7.5 mg/kg twice a day or 5.0 mg/kg three times a day), a study was performed in 10 patients with a diagnosis of parenchymal brain cysticercosis. Each patient received both regimens sequentially according to a randomized, crossover design. Blood and urine samples were taken once the drug steady state had been reached. Plasma levels of albendazole sulfoxide at steady state were determined using a HPLC method. In spite of a great intersubject variability observed with both regimens in the area under the curve (AUC) and in the minimum steady-state plasma concentration (Cp min ss), no statistically significant differences were found in these parameters. We suggest that a regimen of 7.5 mg/kg every 12 h can favorably replace the currently used regimen of 5 mg/kg every 8 h.

Ventricular injection of nerve growth factor increases dopamine content in the striata of MPTP-treated mice

Experimental depletion of dopaminergic striatal neurons was induced in mice with the neurotoxin MPTP. To investigate a possible effect of nerve growth factor on the damaged neurons, we injected 4 micrograms into the right cerebral ventricle of mice three days after the last administration of MPTP. We found a significant increase of dopamine and homovanillic acid in the striatum of MPTP treated mice after NGF administration when compared with dopamine and HVA levels in MPTP-treated control mice (p less than 0.001). The increase of dopamine and homovanillic acid seems to be related to a partial restorative effect of NGF on the damaged dopaminergic cells, since ventricular administration of NGF to normal mice did not increase dopamine or homovanillic acid contents above the levels measured in untreated controls. It appears that administration of nerve growth factor produces a beneficial effect on damaged dopaminergic neurons; this effect could be due to stimulation of neuron sprouting from neurons that survived the toxic effect of MPTP. The increase of dopamine levels was seen 8 days after injection of nerve growth factor and was maintained at least until day 25, showing a lasting persistence of the restorative effect.