Functional morphology of the aardvark tail

The musculoskeletal system of the aardvark (Orycteropus afer) tail was morphologically examined in two adult specimens. The tail musculature comprised three muscular groups, viz. a dorsal sacrocaudal system that consisted of the irregularly oriented Musculus sacrocaudalis dorsalis medialis and M. sacrocaudalis dorsalis lateralis, a lateral inter-vertebral connecting system, and a ventral sacrocaudal system characterized by the thick M. sacrocaudalis ventralis lateralis and M. sacrocaudalis ventralis medialis. Both the dorsal and ventral systems possessed large tendon groups that strengthened the tail structure. Computed tomography (CT) examination showed the presence of large but homogeneous cartilaginous inter-vertebral discs, whereas V-shaped bones were situated at the ventral aspect of the caudal vertebrae at the level of the inter-vertebral discs. CT visualization of the tendons and V-shaped bones in various tail positions suggested that these structures contribute to the tunnel digging action by bearing the trunk weight and lending force when the aardvark are displacing the soil by means of the forelimbs.

Tuberothalamic artery infarctions following coil embolization of ruptured posterior communicating artery aneurysms with posterior communicating artery sacrifice

BACKGROUND AND PURPOSE

Ischemic complications after coil embolization of the PcomA aneurysms are not thoroughly understood, especially in cases in which the PcomA is sacrificed. Our purpose was to examine the preoperative angiographic features and pattern of postoperative cerebral infarctions exhibited by patients who underwent embolization of ruptured PcomA aneurysms with PcomA sacrifice.

MATERIALS AND METHODS

A retrospective review identified 14 patients with ruptured PcomA aneurysms who underwent embolization of the aneurysms in combination with PcomA sacrifice. Preoperative angiographic data, including the Allcock test, postoperative DWI, and neurologic status, were examined.

RESULTS

Elimination of the aneurysm was complete in all cases. Postoperative DWI indicated 7 cases with infarctions (infarction group) and 7 cases without infarctions (noninfarction group). All patients in the infarction group developed infarctions in the vicinity of the tuberothalamic artery. In all 14 cases, a preoperative Allcock test demonstrated a retrograde filling of the PcomA through the P1 segment. The incidence of negative visualizations of the P1 segment on vertebral angiograms was significantly higher in the infarction group (100%) than in the noninfarction group (0%; P = .00058). The mean PcomA diameters, PcomA/P1 ratios, and aneurysm sizes observed in the infarction group were significantly greater than those in the noninfarction group (P < .05, P < .01, and P < .02, respectively). Tuberothalamic artery infarction caused hemiparesis and memory disturbance, which were associated with unfavorable outcomes.

CONCLUSIONS

After the coil occlusion of ruptured PcomA aneurysms with PcomA sacrifice, tuberothalamic artery infarctions tended to occur in cases exhibiting negative visualization of the P1 segment, even when collateral flow was observed with the Allcock test.

Sex differences in the change in health-related quality of life associated with low back pain

PURPOSE

To examine the sex differences in the impact of low back pain (LBP) on health-related quality of life among community-dwelling persons from a nationwide sample.

METHODS

Our analysis enrolled 2,358 participants from among 3,477 randomly selected subjects in Japan. The cumulative days each individual experienced LBP were prospectively measured over 1 month. The Physical Component Summary (PCS) and Mental Component Summary (MCS) in the Short Form 8-item Health Survey were evaluated before and after the study period. Sex differences in the impact of the cumulative number of LBP days on PCS and MCS scores were evaluated using linear regression analysis.

RESULTS

Among the 2,170 participants with complete data, the prevalence of LBP in women (32%) was higher than that in men (25%) during the study period. One-day increases in LBP days were associated with greater decreases in PCS scores among men than among women (-0.72 vs. -0.29, sex difference P < 0.001). In contrast, no relationship was noted between the number of LBP days and the change in MCS score for either sex after adjustment.

CONCLUSIONS

Although a greater incidence of LBP was noted in women, health-related quality of life was more seriously affected in men with the same number of days with LBP in the month.

Limited geographical origin and global spread of sulfadoxine-resistant dhps alleles in Plasmodium falciparum populations

BACKGROUND

Plasmodium falciparum malaria resistant to chloroquine and pyrimethamine originated in limited foci and migrated to Africa. It remains unresolved whether P. falciparum resistance to sulfadoxine, which is conferred by mutations in dihydropteroate synthase (DHPS), evolved following a similar pattern.

METHODS

The dhps locus of 893 P. falciparum isolates from 12 countries in Asia, the Pacific Islands, Africa, and South America was sequenced. Haplotypes of 6 microsatellite loci flanking the dhps locus were determined to define the genetic relationships among sulfadoxine-resistant lineages.

RESULTS

Six distinct sulfadoxine-resistant lineages were identified. Highly resistant lineages appear to have originated only in Southeast Asia and South America. Two resistant lineages found throughout Southeast Asia have been introduced to East Africa, where they appear to have spread.

CONCLUSIONS

The infrequent selection of parasites highly resistant to sulfadoxine and the subsequent migration of resistant lineages from Asia to Africa are similar to the patterns observed in chloroquine and pyrimethamine resistance. These findings strongly suggest that the global migration of resistant parasites has played a decisive role in the establishment of drug-resistant P. falciparum parasites, and that similar patterns may be anticipated for the spread of artemisinin resistance.

Reactive nitrogen oxide species induce dilatation of the intercellular space of rat esophagus

OBJECTIVE

Dilatation of the intercellular space (DIS) of the esophageal epithelium is recognized as one of the earliest histological changes in gastroesophageal reflux disease patients. At the human gastroesophageal junction, reactive nitrogen oxide species (RNOS) are generated luminally through the entero-salivary re-circulation of dietary nitrate. In cases with gastroesophageal reflux, the site of luminal RNOS generation may shift to the distal esophagus. The aim of this study was to investigate whether luminal RNOS exposure could be involved in the pathogenesis of DIS.

MATERIAL AND METHODS

Rat esophageal mucosa was studied with an Ussing chamber model. On the luminal side of the chamber, RNOS were generated by the acidification of physiologic concentrations of sodium nitrite (1.0 or 5.0 mM). Esophageal barrier function was assessed by means of electrophysiological transmembrane resistance and membrane permeability by means of (3)H-mannitol flux. The dimensions of the intercellular spaces were assessed by using transmission electron microscopy.

RESULTS

Administration of acid plus sodium nitrite induced DIS of the esophageal epithelium, and this ultrastructural morphological change was accompanied by a concomitant decrease in the transmembrane resistance and an increase in the epithelial permeability. The DIS induced by luminal RNOS was also confirmed in an in vivo exposure model.

CONCLUSIONS

The present animal study indicates that the RNOS generated by the acidification of salivary nitrite in the presence of refluxed gastric acid in the esophagus could be a luminal factor that is responsible for the induction of DIS. Further studies are warranted to investigate the clinical relevance of the present findings to the human situation.