Comparison between nerve conduction study and high-resolution ultrasonography with color doppler in type 1 and type 2 leprosy reactions.

OBJECTIVE: To analyze the role of high-resolution ultrasonography with color Doppler (HRUS with CD) to diagnose inflammatory activity (IA) in nerves of leprosy patients under type 1 (RT1) and 2 (RT2) reactions compared to Nerve Conduction Studies (NCS). METHODS: Leprosy patients with signs or symptoms suggestive of neuritis (RT1 and RT2) without corticosteroids use were selected. They were evaluated by NCS and subsequently by HRUS with CD. Subacute segmental demyelination and the presence of blood flow, respectively, were considered signs of IA. The two methods were compared for their ability to diagnose patients with leprosy reactions. RESULTS: A total of 257 nerves from 35 patients were evaluated. NCS and HRUS with CD diagnosed IA in 68% and 74% of patients, respectively. When both methods were used concomitantly, the diagnosis rate was 91.4%. HRUS with CD was particular helpful when there was minimal neurophysiological compromise in NCS or when motor potentials were not detected. CONCLUSION: HRUS with CD was able to detect leprosy reactions, especially when combined with NCS. It was especially useful in two opposite situations: nerves with only minor changes and those without motor response in NCS. SIGNIFICANCE: Our data shows the usefulness of HRUS and CD, similar to NCS, as a tool to diagnose leprosy reactions.

Malaria: a sporozoite runs through it.

A recent study reveals new insights into the development of Plasmodium sporozoites, the infectious agents of malaria. These findings may lead to changes in the approach to malaria vaccines and novel interpretations of the mechanisms of immunity to malaria.

MSH/ACTH 4-10 and aging effects on delayed response performance in rats.

The present study examines the effect of MSH/ACTH 4-10 on delayed response performance (DRP) in a two choice version of the Hunter paradigm incorporating the Honzik opaque door modification. DRP was measured in male, Long-Evans rats after administration (IP) of various doses of MSH/ACTH 4-10 or control when animals were young (3 months) and aged (30 months) and aged (30 months). Between MSH/ACTH dose response observations animals received a variety of psychoactive agents of various classes prior to DRP assessment. In addition, DRP was assessed once per month, without drug, from ages 10 to 30 months. MSH/ACTH 4-10, at a dose of 95 ug/kg, significantly enhanced retention of a visual stimulus, while larger doses of MSH/ACTH 4-10 impaired delayed response performance in animals when young. Reversal of anticholinergic-induced DRP impairments by physostigmine and MSH/ACTH 4-10, but not strychnine or methylphenidate, suggests that the effect of MSH/ACTH 4-10 on DRP is specific and may be mediated by enhancement of the cholinergic system(s) in the CNS. Animals began to demonstrate significant impairment in DRP, at longer delays, at the age of 23 months. While confounds such as changes in sensory acuity, motor performance and food preference cannot be totally ignored, the assessment of performance at shorter delay periods served as a control for these problems. No significant age-related changes in DRP at shorter periods of delay were found, indicating that perception and motor capabilities played little role in age-related DRP alterations. Trend analysis revealed that animals demonstrate significant linear and quadratic MSH/ACTH 4-10 dose responses which appear as an inverted "U" in the Hunter paradigm when young. As animals age, this dose response becomes a purely positive linear relationship. Thus, the age-induced decrease in acetylcholine (ACh) levels, and hence MSH/ACTH peptide-induced release, may result in the change in MSH/ACTH dose response profiles. These findings may have clinical implications in the treatment of age-induced or Alzheimer's related cognitive pathologies, which are of cholinergic etiology.

Immunity to malarial antigens on the surface of Plasmodium falciparum-infected erythrocytes.

An indirect immunofluorescence test with fresh non-fixed infected blood as antigen was used to show that antibody in human sera from the Gambia recognized antigens on the surface of Plasmodium falciparum-infected human erythrocytes. Surface immunofluorescence was detected on 90% of erythrocytes infected with trophozoites and schizonts produced in continuous culture of isolates from the Gambia (FCR 3/K+), Brazil and Thailand. Fluorescence was equally strong with a Gambian parasite clone (FCR 3/K-) that lacked knobs, an ultrastructural modification of the erythrocyte membrane associated with parasite sequestration. Immunofluorescence could not be detected with an isolate from Uganda. The surface antigenicity of parasitized erythrocytes was eliminated by chymotrypsin and trypsin treatment. Fluorescence was specific for the surface of trophozoite- and schizont-infected cells on the condition that fresh erythrocytes were added to cultures every 4-5 days (subculture); if fresh erythrocytes were not added for over 2 weeks, a large percentage of non-infected erythrocytes also bound antibody. Normal erythrocytes incubated with media from these cultures also gave positive surface immunofluorescence. Thus, there are two types of antigenicity on erythrocytes: one expressed on infected erythrocytes and another passively absorbed from media to normal erythrocytes when parasites are not subcultured for long periods.

The Duffy blood group and resistance to Plasmodium vivax in Honduras.

To test the hypothesis that the Duffy blood group negative genotype is a factor in resistance to Plasmodium vivax, we determined the Duffy blood group, the malaria antibodies, and the slide-demonstrated infection rates with P. vivax and P. falciparum of 420 persons living in Nueva Armenia, Honduras. In all, 247 persons were Duffy negative. Demonstrated infections with P. falciparum were almost equally distributed between Duffy-positive (5,8%) and Duffy-negative (4.9%) persons. Similarly, Duffy-positive (25.6%) and Duffy-negative (28.2%) persons had equal proportions of indirect fluorescent antibody test titers suggestive of past or present P. falciparum infection. In contrast, all 14 P. vivax infections were found in Duffy-negative persons. There was no evidence suggesting that Duffy-positive and Duffy-negative persons had different exposures to malaria. The Duffy negative genotype FyFy appears to be a factor in resistance to P. vivax.