Neuropsychological alterations and neuroradiological findings in patients with post-traumatic concussion: Results of a pilot study. / Alteraciones neuropsicológicas y hallazgos neurorradiológicos en pacientes con conmoción cerebral postraumática. Resultados de un estudio piloto.

INTRODUCTION: Mild traumatic brain injury (mTBI) has traditionally been considered to cause no significant brain damage since symptoms spontaneously remit after a few days. However, this idea is facing increasing scrutiny. The purpose of this study is to demonstrate the presence of early cognitive alterations in a series of patients with mTBI and to link these findings to different markers of brain damage. METHODS: We conducted a prospective study of a consecutive series of patients with mTBI who were evaluated over a 12-month period. Forty-one (3.7%) of the 1144 included patients had experienced a concussion. Patients underwent a routine clinical evaluation and a brain computed tomography (CT) scan, and were also administered a standardised test for post-concussion symptoms within the first 24hours of mTBI and also 1 to 2 weeks later. The second assessment also included a neuropsychological test battery. The results of these studies were compared to those of a control group of 28 healthy volunteers with similar characteristics. Twenty patients underwent an MRI scan. RESULTS: Verbal memory and learning were the cognitive functions most affected by mTBI. Seven out of the 20 patients with normal CT findings displayed structural alterations on MR images, which were compatible with diffuse axonal injury in 2 cases. CONCLUSIONS: Results from this pilot study suggest that early cognitive alterations and structural brain lesions affect a considerable percentage of patients with post-concussion syndrome following mTBI.

[Neutralization test for lymphocytic choriomeningitis virus for distinguishing between two arenavirus infections in Argentina]. / Prueba de neutralización del virus de la coriomeningitis linfocítica para diferenciar infecciones con dos arenavirus en Argentina.

The active coexistence of two pathogenic arenaviruses, Junin (JUNV) and lymphocytic choriomeningitis (LCMV), in the same region of Argentina, has been known since the early 70's, and records of clinical and subclinical human infections by one and/or the other agent have been continuously produced for the last 25 years. Anti-LCMV antibody is currently searched only by indirect immunofluorescence, a test that shows cross reactions among a number of arenaviruses yielding, in the cases of LCMV and JUNV consecutive infections, a concomitant seroconversion for both viruses, as an inconclusive diagnostic result. In contrast, neutralization (NT) tests reveal arenavirus antibodies directed to unique epitopes on these virus envelopes, thus allowing to disclose the sequence in the cases of consecutive infections. In this paper, the characteristics of neutralization (NT) test for LCMV in cell cultures are described, as well as its performance in the field diagnosis of LCMV human infections. The native LCMV strain Cba An 13065 was inoculated on L-929 cell (ATCC CCL 1), and procedures were followed to perform a constant virus-variable serum NT test. Final points of sera titrations were expressed as the maximal serum dilution that yielded 75% of pfu inhibition. This NT test was assayed on paired serum samples of 36 patients with confirmed Argentine hemorrhagic fever (AHF) (a disease caused by JUNV), who had had a known previous contact with LCMV through IFI. The use of this one test led to confusing diagnosis of the disease due to concomitant seroconversion for JUNV and LCMV. By using NT test, it was shown that: some of them were possibly not infected by LCMV, and that 30/36 cases (83.3%) had a pre-existing level of LCMV antibody, with titers in the range of 5 to 640, remaining unchanged 60 days after the clinical AHF. This shows that NT antibodies to LCMV are not influenced by the outcome of the immune response to JUNV, thus confirming the efficiency of NT test as identificator among arenaviruses. To assess the performance of this NT test in individuals having only IFI antibodies to LCMV, 126 serum samples obtained through serological surveillance in a rural area of Argentina, were used. It was found that NT had improved coincidence with IFI as IFI titers increased. Interpretations were based on the pan-arenavirus antibody response obtained by using IFI as the only test. Results presented herein prove that the described NT test is a valuable tool for the detection of LCMV infections, particularly when a previous infection with LCMV has to be demonstrated during the acute phase of Argentine hemorrhagic fever.

[Isolation of lymphocytic choriomeningitis virus from human individuals]. / Aislamiento del virus de la coriomeningitis linfocitaria de seres humanos.

The activity of lymphocytic choriomeningitis virus (LCMv) in Argentina has been previously reported on the basis of serological evidence in rodents and humans and the isolation of only one strain of LCMv from a Mus domesticus captured in the province of Córdoba. The aim of this paper was to register patients with serological diagnosis of LCM, to isolate and to identify human strains of LCMv in Argentina. During the last 19 years, 15 cases were diagnosed as LCM by immunoflourescent indirect assay (IFI) and enzyme-linked immunosorbent assay (ELISA) but when neutralizing assay (NT) was incorporated, eight cases were classified as confirmed, three as probable and four as negative. The geographic distribution of the cases included three provinces: Córdoba, Buenos Aires and Santa Fe. Viral isolation was attempted in five patients classified as confirmed and only two resulted positive (P5226 and P8573). They were identified as LCMv by IFI and NT. The coexistence of LCMv with other arenaviruses, such as Junin and Oliveros viruses, in the same area, raises the probability of interactions between them, which could modify the virulence and/or pathogenicity for humans associated to genomic changes. Future studies of antigenic, genomic and virulence variability of different Argentine strains of LCMv, as well as the systematic search for human infection, will contribute to define the importance of this viral agent in our country and to implement control measures.

Prueba de neutralización del virus de la coriomeningitis linfocítica para diferenciar infecciones con dos arenavirus en Argentina / [Neutralization test for lymphocytic choriomeningitis virus for distinguishing between two arenavirus infections in Argentina]

The active coexistence of two pathogenic arenaviruses, Junin (JUNV) and lymphocytic choriomeningitis (LCMV), in the same region of Argentina, has been known since the early 70’s, and records of clinical and subclinical human infections by one and/or the other agent have been continuously produced for the last 25 years. Anti-LCMV antibody is currently searched only by indirect immunofluorescence, a test that shows cross reactions among a number of arenaviruses yielding, in the cases of LCMV and JUNV consecutive infections, a concomitant seroconversion for both viruses, as an inconclusive diagnostic result. In contrast, neutralization (NT) tests reveal arenavirus antibodies directed to unique epitopes on these virus envelopes, thus allowing to disclose the sequence in the cases of consecutive infections. In this paper, the characteristics of neutralization (NT) test for LCMV in cell cultures are described, as well as its performance in the field diagnosis of LCMV human infections. The native LCMV strain Cba An 13065 was inoculated on L-929 cell (ATCC CCL 1), and procedures were followed to perform a constant virus-variable serum NT test. Final points of sera titrations were expressed as the maximal serum dilution that yielded 75

of pfu inhibition. This NT test was assayed on paired serum samples of 36 patients with confirmed Argentine hemorrhagic fever (AHF) (a disease caused by JUNV), who had had a known previous contact with LCMV through IFI. The use of this one test led to confusing diagnosis of the disease due to concomitant seroconversion for JUNV and LCMV. By using NT test, it was shown that: some of them were possibly not infected by LCMV, and that 30/36 cases (83.3

) had a pre-existing level of LCMV antibody, with titers in the range of 5 to 640, remaining unchanged 60 days after the clinical AHF. This shows that NT antibodies to LCMV are not influenced by the outcome of the immune response to JUNV, thus confirming the efficiency of NT test as identificator among arenaviruses. To assess the performance of this NT test in individuals having only IFI antibodies to LCMV, 126 serum samples obtained through serological surveillance in a rural area of Argentina, were used. It was found that NT had improved coincidence with IFI as IFI titers increased. Interpretations were based on the pan-arenavirus antibody response obtained by using IFI as the only test. Results presented herein prove that the described NT test is a valuable tool for the detection of LCMV infections, particularly when a previous infection with LCMV has to be demonstrated during the acute phase of Argentine hemorrhagic fever.

Aislamiento del virus de la coriomeningitis linfocitaria de seres humanos. / [Isolation of lymphocytic choriomeningitis virus from human individuals]

The activity of lymphocytic choriomeningitis virus (LCMv) in Argentina has been previously reported on the basis of serological evidence in rodents and humans and the isolation of only one strain of LCMv from a Mus domesticus captured in the province of Córdoba. The aim of this paper was to register patients with serological diagnosis of LCM, to isolate and to identify human strains of LCMv in Argentina. During the last 19 years, 15 cases were diagnosed as LCM by immunoflourescent indirect assay (IFI) and enzyme-linked immunosorbent assay (ELISA) but when neutralizing assay (NT) was incorporated, eight cases were classified as confirmed, three as probable and four as negative. The geographic distribution of the cases included three provinces: Córdoba, Buenos Aires and Santa Fe. Viral isolation was attempted in five patients classified as confirmed and only two resulted positive (P5226 and P8573). They were identified as LCMv by IFI and NT. The coexistence of LCMv with other arenaviruses, such as Junin and Oliveros viruses, in the same area, raises the probability of interactions between them, which could modify the virulence and/or pathogenicity for humans associated to genomic changes. Future studies of antigenic, genomic and virulence variability of different Argentine strains of LCMv, as well as the systematic search for human infection, will contribute to define the importance of this viral agent in our country and to implement control measures.

Prueba de neutralización del virus de la coriomeningitis linfocítica para diferenciar infecciones con dos arenavirus en Argentina. / [Neutralization test for lymphocytic choriomeningitis virus for distinguishing between two arenavirus infections in Argentina]

The active coexistence of two pathogenic arenaviruses, Junin (JUNV) and lymphocytic choriomeningitis (LCMV), in the same region of Argentina, has been known since the early 70s, and records of clinical and subclinical human infections by one and/or the other agent have been continuously produced for the last 25 years. Anti-LCMV antibody is currently searched only by indirect immunofluorescence, a test that shows cross reactions among a number of arenaviruses yielding, in the cases of LCMV and JUNV consecutive infections, a concomitant seroconversion for both viruses, as an inconclusive diagnostic result. In contrast, neutralization (NT) tests reveal arenavirus antibodies directed to unique epitopes on these virus envelopes, thus allowing to disclose the sequence in the cases of consecutive infections. In this paper, the characteristics of neutralization (NT) test for LCMV in cell cultures are described, as well as its performance in the field diagnosis of LCMV human infections. The native LCMV strain Cba An 13065 was inoculated on L-929 cell (ATCC CCL 1), and procedures were followed to perform a constant virus-variable serum NT test. Final points of sera titrations were expressed as the maximal serum dilution that yielded 75

of pfu inhibition. This NT test was assayed on paired serum samples of 36 patients with confirmed Argentine hemorrhagic fever (AHF) (a disease caused by JUNV), who had had a known previous contact with LCMV through IFI. The use of this one test led to confusing diagnosis of the disease due to concomitant seroconversion for JUNV and LCMV. By using NT test, it was shown that: some of them were possibly not infected by LCMV, and that 30/36 cases (83.3

) had a pre-existing level of LCMV antibody, with titers in the range of 5 to 640, remaining unchanged 60 days after the clinical AHF. This shows that NT antibodies to LCMV are not influenced by the outcome of the immune response to JUNV, thus confirming the efficiency of NT test as identificator among arenaviruses. To assess the performance of this NT test in individuals having only IFI antibodies to LCMV, 126 serum samples obtained through serological surveillance in a rural area of Argentina, were used. It was found that NT had improved coincidence with IFI as IFI titers increased. Interpretations were based on the pan-arenavirus antibody response obtained by using IFI as the only test. Results presented herein prove that the described NT test is a valuable tool for the detection of LCMV infections, particularly when a previous infection with LCMV has to be demonstrated during the acute phase of Argentine hemorrhagic fever.

[Prevalence of hepatitis C antibodies in plasma donors for the treatment of Argentine hemorrhagic fever]. / Prevalencia de anticuerpos para el virus de la hepatitis C en donantes de plasma para el tratamiento de la fiebre hemorrágica Argentina.

For Argentine Hemorrhagic Fever, a disease caused by Junin virus (JV), there is an effective treatment, consisting of the transfusion of immune plasma (IP). This plasma is obtained from individuals who have had the disease. Since Hepatitis C virus (HCV) is transmitted parenterally, this study was aimed to estimate the prevalence of anti-HCV in a population of IP donors. In this study, 376 donors (47 females and 329 males) were studied: 95 individuals (24 females and 71 males) who had had FHA but had not received treatment and 88 laboratory workers (57 females and 31 males) who were included as controls. Serum samples were tested by EIA (Abbott, Germany) for HCV, and later confirmed by LIATEK (Organon, Ireland). Antibodies to HCV were detected in 29/376 donors (7.7%), in only 1/95 (1.0%) untreated convalescents of AHF and in 1/ 88 (1.1%) of laboratory workers. Retrospective analysis of the seroconversion for HCV in these individuals demonstrated that in 16/24 donors (66.6%) the infection by HCV was probably associated with the IP transfusion. The data presented herein show how the infection with HCV was disseminated among donors of IP, stressing the risk associated to transfusional practices, and emphasizing the need of vaccination to prevent AHF and also the risk inherent to its treatment.

Evaluation of an enzyme immunosorbent assay for the diagnosis of Argentine haemorrhagic fever.

To elaborate a set of serological tests for the diagnosis of Argentine haemorrhagic fever (AHF), an enzyme-linked immunosorbent assay (ELISA) for detection of specific anti-Junin virus (JV) IgG is described, and its performance is compared with that of the plaque reduction neutralization test (PRNT). The reproducibility, sensitivity, specificity, and confidence limits for positive and negative results for ELISA were statistically analysed. The value of 800 was demonstrated as the lowest positive titer. Titers > or = 800 varied within one (two-fold) dilution in 95.6% of the tests, while the sensitivity and specificity were 99.2% and 98.8%, respectively. The assay yielded 1% of false positives and 0.05% of false negatives. A comparison of ELISA to PRNT in detecting the seroconversion for JV was studied by the chi square test (comparison of proportions in paired samples) and the K parameter for agreement proportion. Comparison of ELISA to PRNT showed no significant difference in the proportions of positive and negative results of these assays (P < 0.01), demonstrating an equivalent performance (K = 0.98) in the diagnosis of AHF. In addition, the simplicity and safety of the procedures involved make this ELISA the most suitable test to detect natural human JV infections.

Activity of a platelet protein kinase that phosphorylates fibrinogen and histone in Argentine hemorrhagic fever.

The activity of a platelet protein kinase that phosphorylates the alpha-chain of fibrinogen and the exogenous substrate histone was evaluated in 28 patients with Argentine hemorrhagic fever, grouped into: 13 mild, 6 moderate and 9 severe clinical forms. Blood samples were obtained before treatment with immune plasma, 4 days later and at recovery. Exogenous histone and fibrinogen phosphorylation were assayed with 25 Ci/mmol (gamma-32P)-ATP. Platelet counts and interferon (IFN) activity were performed simultaneously. Histone phosphorylation was found below normal in all patients during the acute phase of illness. This reduction was coincident with the lowest platelet count and the highest IFN titers. Fibrinogen phosphorylation was similarly reduced. Histone and fibrinogen phosphorylation were still low after 4 days of treatment, when IFN levels were almost undetectable. The low level of phosphorylation was not simply due to the reduced number of platelets and may be another evidence of a platelet abnormality in patients with Argentine hemorrhagic fever.

Influence of different benzodiazepines on the experimental morphine abstinence syndrome.

The abuse of benzodiazepines by narcotic addicts has been well documented. However, the pharmacological basis of this abuse is not clear. In this study the effects of different benzodiazepines (flunitrazepam: 0.5, 1 and 2 mg/kg; nitrazepam: 0.5, 1, 2.5, 5 and 10 mg/kg; diazepam: 0.5, 1, 2.5, 5 and 10 mg/kg; chlordiazepoxide: 0.5, 1, 2.5, 5 and 10 mg/kg; and triazolam: 0.5, 1 and 2 mg/kg) on the morphine withdrawal syndrome in mice have been compared. Drugs were administered 30 min before naloxone-induced withdrawal. All benzodiazepines tested induced similar changes in some of the signs of morphine abstinence: decreased jumping behavior and increased wet dog shake frequency. Jumping behavior was particularly decreased by triazolam and wet dog shakes were mainly increased by flunitrazepam and nitrazepam. Forepaw treading was reduced by flunitrazepam, diazepam and triazolam, increased by nitrazepam and not changed by chlordiazepoxide. Tremor was effectively reduced by diazepam but less reliably by the other benzodiazepines. Teeth chattering was reduced by flunitrazepam and diazepam. These results indicate that benzodiazepines can interfere with the expression of the morphine withdrawal syndrome.

Activity of a platelet protein kinase that phosphorylates fibrinogen and histone in Argentine hemorrhagic fever.

The activity of a platelet protein kinase that phosphorylates the alpha-chain of fibrinogen and the exogenous substrate histone was evaluated in 28 patients with Argentine hemorrhagic fever, grouped into: 13 mild, 6 moderate and 9 severe clinical forms. Blood samples were obtained before treatment with immune plasma, 4 days later and at recovery. Exogenous histone and fibrinogen phosphorylation were assayed with 25 Ci/mmol (gamma-32P)-ATP. Platelet counts and interferon (IFN) activity were performed simultaneously. Histone phosphorylation was found below normal in all patients during the acute phase of illness. This reduction was coincident with the lowest platelet count and the highest IFN titers. Fibrinogen phosphorylation was similarly reduced. Histone and fibrinogen phosphorylation were still low after 4 days of treatment, when IFN levels were almost undetectable. The low level of phosphorylation was not simply due to the reduced number of platelets and may be another evidence of a platelet abnormality in patients with Argentine hemorrhagic fever.

Activity of a platelet protein kinase that phosphorylates fibrinogen and histone in Argentine hemorrhagic fever.

The activity of a platelet protein kinase that phosphorylates the alpha-chain of fibrinogen and the exogenous substrate histone was evaluated in 28 patients with Argentine hemorrhagic fever, grouped into: 13 mild, 6 moderate and 9 severe clinical forms. Blood samples were obtained before treatment with immune plasma, 4 days later and at recovery. Exogenous histone and fibrinogen phosphorylation were assayed with 25 Ci/mmol (gamma-32P)-ATP. Platelet counts and interferon (IFN) activity were performed simultaneously. Histone phosphorylation was found below normal in all patients during the acute phase of illness. This reduction was coincident with the lowest platelet count and the highest IFN titers. Fibrinogen phosphorylation was similarly reduced. Histone and fibrinogen phosphorylation were still low after 4 days of treatment, when IFN levels were almost undetectable. The low level of phosphorylation was not simply due to the reduced number of platelets and may be another evidence of a platelet abnormality in patients with Argentine hemorrhagic fever.

Comparative study in mice of flunitrazepam vs. diazepam on morphine withdrawal syndrome.

1. There is some evidence that benzodiazepine may modify the opioid withdrawal syndrome. We have investigated the effect of two different benzodiazepines, diazepam and flunitrazepam, on the morphine withdrawal syndrome experimentally induced in mice. 2. Opiate dependence has been induced by administration of morphine s.c. over a period of five days. Two hours after last morphine administration withdrawal syndrome was induced by s.c. injection of naloxone (5mg/kg). The number of jumps, wet-dog-shakes and paw tremor, and the presence or absence of ptosis, diarrhea, teeth chattering and body tremor were evaluated after naloxone injection. 3. All the signs of morphine withdrawal syndrome was antagonized by flunitrazepam and diazepam, only wet-dog-shake was strongly increased by flunitrazepam.

Correlation between endogenous interferon and the clinical evolution of patients with Argentine hemorrhagic fever.

To explore the endogenous interferon levels in patients of Argentine hemorrhagic fever (AHF) with different clinical evolution of the disease, 29 fatal and 33 surviving cases of AHF were analyzed. As previously reported, the titers of endogenous alpha-IFN in patients with AHF are very high, generally between 2,000 and 64,000 IU/ml. Thus far, these are the highest levels of circulating interferon detected in any human viral disease. In this study it was found that during the second week of evolution the titers of interferon were significantly higher in fatal cases than in survivors. Therefore, very high levels of interferon have a prognostic value in AHF.

Endogenous interferon in Argentine hemorrhagic fever.

The induction of endogenous interferon (IFN) was studied in 28 cases of Argentine hemorrhagic fever (AHF), a severe systemic disease caused by Junin virus. Serum samples were taken daily during the acute period, both before and after administration of immune plasma. This form of treatment has been found to reduce mortality when given early in the course of AHF. High titers of circulating IFN were present in the serum samples taken before treatment. IFN titers drastically dropped after transfusion of immune plasma. The antiviral activity was stable at pH 2 and was completely neutralized only by antibodies against IFN-alpha. Thus, we concluded that circulating endogenous IFN in patients with AHF can be considered as typical IFN-alpha. Fever, chills, and backache were associated with the higher levels of IFN. An inverse correlation between days of evolution of the disease and IFN activity was also observed.