Sequence variants in the pancreatic islet beta-cell inwardly rectifying K+ channel Kir6.2 (Bir) gene: identification and lack of role in Caucasian patients with NIDDM

The septate gregarine parasites of flour beetles (Tribolium spp.) include Gregarina minuta Ishii, 1914, a relatively small species in which both primite and satellite possess an obvious protomerite, and a larger species that lacks the satellite protomerite. The latter species has been placed in the genera Didymophyes and Hirmocystis by various authors, but studies reported here demonstrate that this species, herein described as Gregarina triboliorum, exhibits early pairing and produces oocyst chains, both characteristics of the genus Gregarina. The oocysts of this new species are described for the first time. In addition, experimental infections using oocyst from single gametocysts reveal that oocyst chain number is variable but is typically 1, 2, or 4. Prior experiments involving a related beetle, Tenebrio molitor, demonstrated extreme host specificity within the 4 Gregarina species parasitizing larval and adult hosts. However, G. triboliorum is not limited either stadially or specially, infecting both adults and larvae of Tribolium confusum and Tribolium castaneum.     

Scanning ion conductance microscopy of living cells

Currently there is a great interest in using scanning probe microscopy to study living cells. However, in most cases the contact the probe makes with the soft surface of the cell deforms or damages it. Here we report a scanning ion conductance microscope specially developed for imaging living cells. A key feature of the instrument is its scanning algorithm, which maintains the working distance between the probe and the sample such that they do not make direct physical contact with each other. Numerical simulation of the probe/sample interaction, which closely matches the experimental observations, provides the optimum working distance. The microscope scans highly convoluted surface structures without damaging them and reveals the true topography of cell surfaces. The images resemble those produced by scanning electron microscopy, with the significant difference that the cells remain viable and active. The instrument can monitor small-scale dynamics of cell surfaces as well as whole-cell movement.     

Apolipoprotein B and AI distributions in the United States, 1988-1991: results of the National Health and Nutrition Examination Survey III (NHANES III)

Serum apolipoproteins (apo) B and AI were measured in a probability sample of the noninstitutionalized US civilian population, ages > or = 4 years, which included non-Hispanic whites, non-Hispanic blacks, and Mexican-Americans. Apo B concentrations were the same in males and females, lower in black males than in other males, low in childhood (approximately 0.80 g/L) and increasing to approximately 1.2 g/L in adults, and higher in younger women on hormones. Apo AI was higher in females than males, higher in blacks than in others, remained constant from childhood to adulthood (approximately 1.35 g/L) in males, but increased with age (approximately 1.30 g/L to approximately 1.55 g/L) in females, and was higher in women taking hormones. These are the first national probability estimates of apo B and apo AI in the US and are referable to the WHO-IFCC First International Reference Materials for apo AI and B.     

Anti-plasmodial and anti-trypanosomal activity of synthetic naphtho[2,3-b]thiopen-4,9-quinones

Naphtho[2,3-b]thiophen-4,9-quinone and five derivatives were prepared using the Friedel-Crafts reaction and tandem-lithiation of aromatic diethylamides. These quinones were evaluated for their trypanocidal and anti-plasmodial activities by their effects on: (1) growth of epimastigote forms of Trypanosoma cruzi in vitro, (2) lysis of trypomastigote forms of T. cruzi in murine blood, (3) growth of Plasmodium falciparum in vitro, and (4) inhibition of the recombinant enzyme trypanothione reducatase. The parent compound, naphtho[2,3-b]thiophen-4,9-quinone (3a), was among the most active quinone tested in vitro against P. falciparum at 0.2 microM. However, it was inactive against P. berghei-infected mice treated with 2.3 mmol/kg daily for 5 days. Most of the quinones prepared were active against T. cruzi epimastigotes in culture but exhibited weak activity at 4 degrees C against trypomastigotes in murine blood as well against the enzyme trypanothione reducatase. Further structural modifications will be necessary to improve the in vivo activity of the naphthothiophenquinones.     

Fueguian cranial morphology: the adaptation to a cold, harsh environment

Craniometric data from the three extinct tribes that inhabited Tierra del Fuego (Selk'nam, Yámana, and Kawéskar) were gathered following Howell's measurement technique. We studied 180 skulls preserved at thirteen different institutions. Analysis of variance (ANOVA) between groups showed that morphological similarities among Fueguian groups are far more important than some differences between marine (Yámana and Kawéskar) and terrestrial (Selk'nam) groups. A principal component analysis (PCA) generated from the correlation matrix shows that Fueguians fall as outliers with respect to the typical Mongoloid morphology. In addition, a UPGMA tree generated from a squared Euclidean distance matrix indicates that Fueguian groups have a morphological pattern that is very distinct from that of other present-day Amerindian groups, with the exception of the Eskimos. One of the variables that contributes substantially to the differentiation of Eskimos and Fueguians is the nasal height. This suggests that nasal morphology in both groups could be a response to adaptive pressures related to the cold environment. However, other morphological particularities of Fueguian skulls, such as craniofacial robustness and variables of craniofacial width, can be attributed to a large masticatory stress. As a whole, the morphological features of Fueguian groups can be regarded as a general adaptive response to a very harsh environment, along with the retention of some plesiomorphic features. Assuming that the initial entry in Tierra de Fuego took place around 10,000 years BP, before the disappearance of the last land bridges in the Magellan Straits, then this adaptation might have arisen in a relatively short period, hastened by the extreme environmental conditions.