Effect of ammonia on in vivo and in vitro immune responses

The effects of exposure of animals to ammonia on their delayed type of dermal response, the mitogenic and antigenic responses of their lymphocytes, and the bactericidal and phagocytic activities of their alveolar macrophages were examined. Experimental guinea pigs vaccinated with Mycobacterium bovis BCG were exposed to 3.75 micrograms of ammonia per dl of air (50 ppm) or 6.75 micrograms of ammonia per dl of air (90 ppm), whereas control animals also vaccinated with BCG were maintained in the normal environment. The delayed type of dermal response to tuberculin injected 3 weeks later was significantly (P less than 0.05) less in experimental animals exposed to 6.75 micrograms of ammonia per dl than in control animals. In vitro, the response of blood lymphocytes and bronchial lymphocytes to phytohemagglutinin, concanavalin A, and tuberculin stimulation was significantly (P less than 0.01) less than the response of lymphocytes from control animals. The response of normal blood lymphocytes to phytohemagglutinin incubated in medium containing 1 or 10 mg of ammonia per dl was significantly (P less than 0.01) reduced as compared with the response of lymphocytes incubated without ammonia. The viability of lymphocytes incubated with these concentrations of ammonia was significantly (P less than 0.01) affected. There was no significant difference in the bactericidal or phagocytic activities of alveolar macrophages collected from animals exposed to ammonia and control animals. However, ammonia added to the culture of alveolar macrophages from normal animals significantly inhibited their bactericidal activity.     

Short-term CD4 cell response after highly active antiretroviral therapy initiated at different times from seroconversion in 1,500 seroconverters

The effect of HIV infection duration and CD4 cell count on short-term CD4 response was evaluated in treatment-naive seroconverters using logistic regression adjusted for CD4 count before highly active antiretroviral therapy (HAART) as well as for exposure category, age, sex, acute infection, and cohort. This association was also investigated in pretreated seroconverters, further adjusting for prior therapy. CD4 response (increase of >100 cells/microL at 6 months) was more likely if HAART was initiated in the first year following seroconversion (OR = 1.50 [95% CI: 1.07-2.10] compared with 2-5 years). There was no improvement in response from initiating HAART with CD4 count >350 cells/microL compared with 201 to 350 cells/microL. Below 200 cells/microL, however, the chance of a CD4 response appeared to be reduced (OR = 0.72 [95% CI: 0.40-1.28] for 0-200 cells/microL compared with 201-350 cells/microL, P = 0.26). Results were similar for pretreated individuals. Further, in pretreated individuals, a CD4 response was less likely if the CD4 nadir was lower than the pre-HAART CD4 count (OR = 0.18 [95% CI: 0.10-0.36] for >150 cells/microL difference between nadir and pre-HAART CD4 count vs. no difference, P < 0.001). Given the limitations of observational studies, particularly the inability to control for unmeasured confounders, these findings suggest that the initiation of HAART within the first year following seroconversion appears to improve short-term immunologic response. After that time, there is little to be gained in terms of short-term response from initiating HAART before reaching a CD4 count of 200 cells/microL.     

Clinicopathological significance of PTEN and bcl2 expressions in oral squamous cell carcinoma

A high frequency of mutations at the PTEN locus has been noticed in carcinoma of oral. However, the role of PTEN alternations and its association with outcome variables in the genesis of oral carcinoma is not understood fully. The purpose of our study was to examine the impact of PTEN and Bcl2 in the genesis of Squamous cell carcinoma of oral. Total numbers of 60 histopathologically confirmed cases of Squamous Cell Carcinoma and 15 cases of inflammatory lesion of oral specimens were studied. We assessed PTEN and bcl2 overexpression by the use of anti-PTEN and anti-bcl2 antibody through immunohistochemistry as directed by the manufacturer. There was progressive loss of PTEN expression from inflammatory lesion to OSCC (p<0.05). Significant differences were found for PTEN expression between inflammatory lesion and OSCC. The difference in expression pattern of PTEN in gender did not reach statistical significance (p>0.05). The expression of bcl2 was found to be restricted to tumor cells in well and moderately differentiated tumors. The intense expression of bcl2 was observed throughout the tumor cell in poorly differentiated tumors.The Overexpression of bcl2 and loss of PTEN expression were correlated to poor differentiation, lymph node involvement and late stages. Thus, alteration of PTEN and bcl2 is likely an important molecular event in pathogenesis and carcinogenesis of oral carcinoma.     

Evolution of drug-resistance genes in Plasmodium falciparum in an area of seasonal malaria transmission in Eastern Sudan

We investigated the evolution of drug-resistant Plasmodium falciparum in a village in eastern Sudan. The frequencies of alleles of 4 genes thought to be determinants of drug resistance were monitored from 1990 through 2001. Changes in frequencies of drug-resistance genes between wet and dry seasons were monitored from 1998 through 2000. Parasites were also typed for 3 putatively neutral microsatellite loci. No significant variation in frequencies was observed for the microsatellite loci over the whole study period or between seasons. However, genes involved in resistance to chloroquine showed consistent, significant increases in frequencies over time (rate of annual increase, 0.027/year for pfcrt and 0.018/year for pfmdr1). Genes involved in resistance to the second-line drug used in the area (Fansidar) remained at low frequencies between 1990 and 1993 but increased dramatically between 1998 and 2000, which is consistent with the advent of Fansidar usage during this period. For mutant alleles of the primary drug-resistance targets for chloroquine and pyrimethamine, higher frequencies were seen during the dry season than during the wet season. This cyclical fluctuation in drug-resistance genes most likely reflects seasonal variation in drug pressure and differences in the fitness of resistant and sensitive parasites.     

Virological and immunological effects of short-course antiretroviral therapy in primary HIV infection

BACKGROUND: National and international guidelines call for the treatment of primary HIV infection (PHI) with combination antiretroviral therapy, although the ideal timing and duration of this intervention is unknown. Recent immunological studies of antiretroviral therapy on small numbers of patients with PHI have reported preservation of HIV-specific CD4 T-helper responses, ordinarily lost in the absence of intervention. We sought to investigate whether a short course of antiretroviral therapy (SCART) at PHI was sufficient to preserve HIV-specific cellular immunity. METHODS: Forty-five subjects with confirmed PHI were offered SCART at diagnosis. HIV specific cellular immune responses and virological parameters were assessed at monthly intervals. RESULTS: Thirty-seven of the subjects chose SCART at PHI, and achieved a plasma viral load < 50 RNA copies/ml by a median of 10 weeks (range, 4-32 weeks). Two of the 45 individuals had evidence of genotypic HIV drug resistance at baseline, and none developed new mutations following therapy. All patients who received SCART at PHI showed preservation of HIV-specific CD4 T-helper responses up to 64 weeks off SCART. CONCLUSION: SCART at PHI was safe, did not induce the development of drug resistance, and appeared sufficient to preserve HIV-specific CD4 T-helper responses. However, PHI is highly heterogeneous, and a large-scale randomized trial of SCART at PHI is now needed.     

High-level chloroquine resistance in Sudanese isolates of Plasmodium falciparum is associated with mutations in the chloroquine resistance transporter gene pfcrt and the multidrug resistance Gene pfmdr1

Polymorphisms were examined in 2 Plasmodium falciparum genes, as were chloroquine responses of clones and isolates from a village in eastern Sudan. There was a significant association between an allele of the P. falciparum chloroquine resistance transporter gene (pfcrt-T76) and both in vitro and in vivo resistance. There was a less significant association with the multidrug resistance gene pfmdr1-Y86 allele. A significant association between pfmdr1-Y86 and pfcrt-T76 was apparent among resistant isolates, which suggests a joint action of the 2 genes in high-level chloroquine resistance.     

Splenic function in children with sickle cell disease: two different patterns in Saudi Arabia

Splenic function in 35 Saudi children homozygous for sickle cell disease (age range 3-9 years) was studied using radioactive colloid scans. Two different patterns emerged. Splenic dysfunction was demonstrated in more than 80% of children who were originally from the south-western part of the country. They were found to have low HbF levels. In contrast normal or nearly normal splenic function was found in all patients from the Eastern Province in whom HbF levels were high. These different patterns of splenic function may contribute to the severe and mild forms of sickle cell disease seen in Saudi Arabia.     

Differential antibody recognition of FC27-like Plasmodium falciparum merozoite surface protein MSP2 antigens which lack 12 amino acid repeats

Three alleles of the FC27-type allelic family of the MSP2 gene of the malaria parasite Plasmodium falciparum have been sequenced from parasites from the field (The Gambia and Tanzania). These alleles lack the 12 amino acid repeat units which are usual in this family of MSP2 alleles. We have investigated the recognition by sera from an endemic area (The Gambia) of three recombinant MSP2 proteins that have 5, 1 and no copies of this repeat region. Antibody recognition of these recombinant proteins varied according to the number of repeats present. High titre antibody levels were seen with most sera using the recombinant protein with 5 × 12-mer repeats, whereas only low responses were measured using proteins containing 1 or no 12-mer repeats. Several sera entirely failed to recognise the protein which lacked 12-mer repeats. The data suggest that variation in the number of tandem repeat sequences could allow the parasite to avoid high avidity antibody binding and this may allow escape from immune recognition.