Genetic evidence that RI chloroquine resistance of Plasmodium falciparum is caused by recrudescence of resistant parasites

Isolates of Plasmodium falciparum from patients in a Sudanese village exhibiting RI resistance to chloroquine have been typed for allelic variants of 2 merozoite surface antigens, MSP1 and MSP2. Blood forms were taken from each patient before chloroquine was administered, and after parasites had reappeared following treatment. Each patient was found to be infected with genetically different parasites. However, in each patient the parasites of the recrudescent infections possessed the same alleles of each gene as those of the primary infection. The results show that the parasites which reappeared after chloroquine were a genuine recrudescence of the primary forms, and not derived from a new infection.

Ten years of experience with patients with chronic active liver disease variceal bleeding: ablative versus selective decompressive therapy

BACKGROUND

Variceal hemorrhage is an added major threat to survival in patients with chronic active liver disease (CALD). The hemodynamic consequences of surgical therapy and the continued activity of the underlying liver disease both contribute to the hepatic dysfunction and determine patient survival.

METHODS

Two hundred and seventy two consecutive cases of (Child A or B) variceal bleeding with chronic hepatitis were surgically treated during a 10-year period. Histologic chronic active hepatitis (CAH) was documented in 160 (59%) patients, whereas chronic persistent hepatitis (CPH) was evident in 112 (41%). The applied surgical procedure was distal splenorenal shunt (DSRS) in 99 (36%) patients, splenectomy and gastroesophageal devascularization (SGD) in 108 (40%), and splenectomy with left gastric ligation (SLGL) in 65 (24%) patients. The preoperative data base obtained on these patients was matched comparing the three surgical modalities within each pathologic group (p > 0.05).

RESULTS

The operative mortality was low among the patients with CAH (DSRS, 5.1%; SGD, 4.2%) with no deaths occurring in the CPH group. Among the individuals with CAH, recurrent variceal hemorrhage occurred significantly (p < 0.05) more often after SLGL (26%) and SGD (17%) than after DSRS (5%). Sclerotherapy rescued 93% (SGD) and 70% (SLGL) of the patients with rebleeding. DSRS significantly (p < 0.05) increased the risk of encephalopathy (28%) compared with SGD (4.2%) and SLGL (8%). The morbidity rates were quite low among the patients with CPH with no significant (p > 0.05) differences noted when the three surgical modalities were compared. Both groups experienced a significant (p < 0.05) increase in aspartate aminotransferase levels after the three procedures with a significant (p < 0.05) increase in bilirubin level occurring only after DSRS. The 5-year survival rate for the patients with variceal bleeding with CAH was 76% (DSRS), 73% (SGD), and 88% (SLGL). The leading causes of death were liver failure after DSRS (70%), variceal hemorrhage after SLGL (60%), and equally divided between septicemia (43%) and liver failure (43%) after SGD. The patients with CPH had a better 5-year survival of 89% (DSRS) and 100% (nonshunt operation).

CONCLUSIONS

These data showed that (1) CALD is common among cases of variceal bleeding; (2) elective surgical treatment of variceal hemorrhage in patients with Child A or B CALD has a low operative mortality; (3) SLGL backed up by sclerotherapy is a better surgical alternative to either selective shunt or SGD in patients with active hepatitis, and (4) both DSRS and nonshunt operation are equally good surgical options for patients with CPH.

Interactions of cadmium and nickel with K channels of vascular smooth muscle

Previous studies have shown that environmentally significant concentrations (< 1 microM) of large divalent cations increased vascular tone in resistance arteries. Because K channels are important regulators of vasoactivity, we studied the interactions of Cd and Ni on K channels of smooth muscle from bovine mesenteric artery using the planar bilayer method. We describe one type of small, Ca-insensitive K channel (Ks), and two types of large, Ca-activated K channels ([BK(Ca)], Kc1 and Kc2, that were identical with respect to single-channel conductance and K/Cl selectivity, but differed in Ca/voltage sensitivity. Neither metal affected the open probability (po) of Ks but both Cd and Ni, in concentrations greater than or equal to 100 nM, similarly decreased po of Kc1 and Kc2 from the intracellular side of the channel in the presence of 1 microM Ca. The effects of both Cd and Ni were reversed by 0.1 mM Ca. It is concluded that Cd and Ni, in concentrations less than 1 microM, can interact with the Ca/voltage sensor and inhibit BK(Ca) channels of vascular smooth muscle. These effects may partially explain the vascular tension induced by large divalent cations.

The vestibular aqueduct in congenital deafness: evaluation by the axial projection

Thirty-two patients with congenital neurosensory hearing loss demonstrated dilatation of the peripheral limb of the vestibular aqueduct as visualized on pluridirectional tomograms. Multiple additional anomalies involving most frequently the cochlea (15 patients) but also the ossicles (three patients) or vestibule (one patient) were associated. The axial-pyramidal (Poschl) projection was of great value in evaluation of the vestibular aqueduct and cochlea. The technique, clinical correlation, and surgical implications are discussed.