Glucose-6-phosphate dehydrogenase deficiency and homozygous sickle cell disease in Congo

G6PD genotypes were determined in Brazzaville (Congo) on 188 HbSS patients (109 females, 79 males) and 210 controls (115 females and 95 males) with HbAA. DNA samples were analyzed by the polymerase chain reaction (PCR). The frequencies of G6PD B, A+ and A- alleles were 56.9, 20.8 and, 22.2% in the patients versus 56.3, 21.2 and, 22.5% in the controls, respectively. The prevalence of G6PD genotypes in HbSS did not differ (p > 0.05) from that found in the controls. Prevalence of G6PD deficiency did not change when patients were stratified by age, suggesting that there is no advantage of the association of G6PD deficiency with HbSS. Red blood cell count, mean corpuscular volume and mean corpuscular hemoglobin were not modified by the G6PD genotypes, while Hb level was lower in HbSS with G6PD A-. Our study suggests that in Congo, G6PD deficiency does not offer any biological advantage to sicklers.

HB Les Andelys [alpha83(F4)LEU-->PRO]: a new moderately unstable variant

Hb Les Andelys [alpha83(F4)Leu-->Pro] is a mildly unstable variant that was found during glycated hemoglobin measurement in a French family. In this hemoglobin molecule the affected site, in the alpha chain, and the amino acid substitution are identical to those of Hb Santa Ana, an unstable beta chain variant. The structural abnormality was demonstrated by protein chemistry methods, involving, in addition to the classical techniques, a selective precipitation of the abnormal hemoglobin by isopropanol and a mass spectrometry analysis of the alphaT-9 peptide following carboxypeptidase digestion. DNA sequencing demonstrated that the mutation was CTG-->CCG at codon 83 of the alpha2 gene.

Murine AIDS protects mice against experimental cerebral malaria: down-regulation by interleukin 10 of a T-helper type 1 CD4+ cell-mediated pathology

The retrovirus LP-BM5 murine leukemia virus induces murine AIDS in C57BL/6 mice that has many similarities with human AIDS; Plasmodium berghei ANKA causes experimental cerebral malaria in the same strain of mice. The outcome of malaria infection was studied in mice concurrently infected with the two pathogens. The retrovirus significantly reduced the gravity of the neurological manifestations associated with Plasmodium berghei ANKA infection. The protection against experimental cerebral malaria induced by murine AIDS increased with duration of viral infection and, hence, with the severity of the immunodeficiency. Interleukin 10, principally from splenic T cells, was shown to play a crucial role in this protection.

Alterations of uninfected red blood cells in malaria

Red blood cell (RBC) negative charges and resistance to linoleic acid (LNA)-induced lysis were studied in Plasmodium yoelii-infected mice and in malaria (P. falciparum)-affected individuals. RBCs from mice infected with P. yoelii showed a progressive decrease in the net surface negative charges at 24 h after infection, reaching a minimal value on day 3, followed by a second phase that was characterised by a recovery to normal levels on day 6. Resistance to linoleic acid follows similar kinetics. These alterations preceded the appearance of parasites in the peripheral blood. A similar increase in LNA-induced lysis was observed in RBCs from malaria-affected individuals. These early membrane alterations of uninfected RBCs could be responsible for spreading of infection and RBC lysis during infection.

Microtubule disruption interferes with the structural and functional integrity of the apical pole in primary cultures of rat hepatocytes

The effect of microtubule disruption on the development and maintenance of cell polarity was studied in rat hepatocytes cultured as primary monolayers in the presence of colchicine or nocodazole. Addition of colchicine immediately after plating did not inhibit the generation of bile canaliculi (the apical pole) after 1 day of culture, as judged by electron microscopic examination, and did not allow penetration of Ruthenium Red through the tight junctions. However, the bile canaliculi developed in the presence of colchicine or nocodazole were not fully normal since they were not able to concentrate fluorescein diacetate in their lumina, and did not enrich with proteins of the apical plasma membrane domain, as control cells did. When the drugs were added after 1 or 2 days of culture, the new bile canaliculi appeared to be unaffected when examined by electron microscopy, but many of them did not concentrate fluorescein and were not enriched with apical membrane proteins within 4 to 24 h after drug addition. Whenever the drugs were added, the proteins that would normally concentrate on the membrane of the bile canaliculi accumulated intracellularly in endocytic vesicles after 2 to 4 h of drug treatment, and in vacuoles resembling lysosomes when the drugs were maintained for 24 h or more. These results show that microtubule disruption does not inhibit the structural reconstitution of bile canaliculi, but impairs their normal function and the transport of proteins of the apical plasma membrane domain.