Identifying dental panoramic radiograph features for the screening of low bone mass in postmenopausal women

A retrospective cohort study was performed to evaluate the use of panoramic radiographs as a screening tool for low bone mass in postmenopausal women. Female subjects aged ≥50 years were included. The predictor variables were gonial angle, antegonial angle, mandibular cortical bone integrity, periodontal disease status, and number of remaining teeth. The primary outcome variable was bone mineral density status. Descriptive and logistic regression statistics were computed; P<0.05 was considered significant. The sample was composed of 273 subjects, aged 50-89 years. Visual assessment of mandibular cortical bone integrity demonstrated a statistically significant correlation with low bone mass diagnosis on univariate logistic regression (P=0.019), but lost significance on multivariate analysis with age, body mass index, and number of remaining teeth (P=0.6). A visual estimation of the mandibular cortical bone integrity from panoramic radiographs may be useful for identifying postmenopausal women at high risk for osteoporosis.

Long 5' leaders inhibit removal of a 3' trailer from a precursor tRNA by mammalian tRNA 3' processing endoribonuclease

Mammalian tRNA 3' processing endoribonuclease (3' tRNase) can remove a 3' trailer from various pre-tRNAs without 5' leader nucleotides. To examine how 5[prime] leader sequences affect 3' processing efficiency, we performed in vitro 3' processing reactions with purified pig 3' tRNase and pre-tRNAArgs containing a 13-nt 3' trailer and a 5[prime] leader of various lengths. The 3' processing was slightly stimulated by 5[prime] leaders containing up to 7 nt, whereas leaders of 9 nt or longer severely inhibited the reaction. Structure probing indicated that the 5' leader sequences had little effect on pre-tRNA folding. Similar results were obtained using pre-tRNA(Val)s containing a 5' leader of various lengths. We also investigated whether 3'tRNase can remove 3' trailers that are stably base-paired with 5' leaders to form an extended acceptor stem. Even such small 5' leaders as 3 and 6 nt, when base-paired with a 3' trailer, severely hindered removal of the 3' trailer by 3' tRNase.

RNA heptamers that direct RNA cleavage by mammalian tRNA 3' processing endoribonuclease

Mammalian tRNA 3' processing endoribonuclease (3' tRNase) can recognize and cleave any target RNA that forms a precursor tRNA-like complex with another RNA. Various sets of RNA molecules were tested to identify the smallest RNA that can direct target RNA cleavage by 3' tRNase. A 3' half tRNAArgwas cleaved efficiently by 3' tRNase in the presence of small 5' half tRNAArgvariants, the D stem-loop region of which was partially deleted. Remarkably, 3' tRNase also cleaved the 3' half tRNAArgin the presence of a 7 nt 5' tRNAArg composed only of the acceptor stem region with a catalytic efficiency comparable with that of cleavage directed by an intact 5' half tRNAArg. The catalytic efficiency of cleavage directed by the heptamer decreased as the stability of the T stem-loop structures of 3' half tRNAArg variants decreased. No heptamer-directed cleavage of a 3' half tRNAArg without T stem base pairs was detected. A heptamer also directed cleavage of an HIV-1 RNA containing a stable hairpin structure. These findings suggest that in the presence of an RNA heptamer, 3' tRNase can discriminate and eliminate target RNAs that possess a stable hairpin adjacent to the heptamer binding sequence from a large complex RNA pool.

Endoscopic third ventriculocisternostomy: MR assessment of patency with 2-D cine phase-contrast versus T2-weighted fast spin echo technique

PURPOSE

To determine if fast spin-echo T2 (FSE) is of equal value to flow-sensitive 2D cine phase-contrast (CPC) to assess patency of endoscopic third ventriculocisternostomies (VC).

PATIENTS AND METHODS

We reviewed clinical charts and MR scans of 27 patients who underwent third VC for treatment of obstructive hydrocephalus. Thirty-nine postoperative scans included both sequences and were assessed for the presence or absence of flow-related signal changes.

RESULTS

In 28 cases, FSE, CPC, and clinical findings suggested patency. In 1 case, CPC and FSE suggested occlusion, which was confirmed clinically and operatively. In the remaining cases, FSE showed better clinical correlation than did CPC.

CONCLUSION

The assessment of third VC patency with FSE, a sequence available on most clinical scanners without a requirement for special hardware and software, is at least as sensitive in the qualitative assessment of VC function as CPC.

Rapid mini-preparations of total RNA from bacteria

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Preoperative self-efficacy and postoperative behaviors

Preoperative instruction has been found to decrease postoperative complications; however, the mechanisms through which preoperative instruction exerts its effects remain unknown. In this study, the relationship between preoperative self-efficacy and postoperative behaviors was investigated. Subjects were 68 cholecystectomy patients. Subjects' scores on the efficacy expectations subscale were related significantly to postoperative deep breathing, ambulation, and recall of expected events; scores on the outcome expectations subscale were related significantly to postoperative requests for pain medication. Self-efficacy theory provided a link between self perceptions and behavior and may be the mechanism through which preoperative instruction exerts its effects.

Synthesis and biological activity of certain 6-substituted and 2,6-disubstituted 2'-deoxytubercidins prepared via the stereospecific sodium salt glycosylation procedure

A number of 6-substituted and 2,6-disubstituted pyrrolo[2,3-d]pyrimidine 2'-deoxyribonucleosides were prepared by the direct stereospecific sodium salt glycosylation procedure. Reaction of the sodium salt of 4-chloro-6-methyl-2-(methylthio)pyrrolo[2,3-d]pyrimidine (6a) or 4,6-dichloro-2-(methylthio)pyrrolo[2,3-d]pyrimidine (6b) with 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-alpha-D-erythro-pentofuranose (9) provided the corresponding N7 2'-deoxy-beta-D-ribofuranosyl blocked derivatives (8a and 8c) which, on ammonolysis, gave 4-amino-6-methyl-2-(methylthio)-7-(2-deoxy-beta-D-erythro-pentofuranosyl )pyrrolo[2,3-d]pyrimidine (11a) and 4-amino-6-chloro-2-(methylthio)-7-(2-deoxy-beta-D-erythro-pentofuranosyl )pyrrolo[2,3-d]pyrimidine (11b), respectively. Dethiation of 11a and 11b afforded 6-methyl-2'-deoxytubercidin (10a) and 6-chloro-2'-deoxytubercidin (10b), respectively. Dehalogenation of 10b provided an alternate route to the reported 2'-deoxytubercidin (3a). Application of this glycosylation procedure to 4,6-dichloro and 4,6-dichloro-2-methyl derivatives of pyrrolo[2,3-d]pyrimidine (15a and 15b) gave the corresponding blocked 2'-deoxyribonucleosides (18a and 18b), which on ammonolysis furnished 10b and 4-amino-6-chloro-2-methyl-7-(2-deoxy-beta-D-erythro- pentofuranosyl)pyrrolo[2,3-d]pyrimidine (17), respectively. This stereospecific attachment of the 2-deoxy-beta-D-ribofuranosyl moiety appears to be due to a Walden inversion at the C1 carbon by the anionic heterocyclic nitrogen. Controlled deacylation of 4-chloro-7-(2-deoxy-3,5-di-O-p-toluoyl-beta-D-erythro-pentofuranosyl) pyrrolo[2,3-d]pyrimidine (20a) gave 4-chloro-7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d] pyrimidine (20b). Dehalogenation of 20b gave the 2'-deoxynebularin analogue 7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d]pyrimidine (19), and reaction of 20b with thiourea gave 7-(2-deoxy-beta-D-erythro-pentofuranosyl)pyrrolo[2,3-d]pyrimidine-4(3H)- thione (21). All of these compounds were tested in vitro against certain viruses and tumor cells. Only compounds 12a, 20b, and 21 showed significant activity against measles in vitro, and the activity is comparable to that of ribavirin. Although compounds 3a and 12b are slightly more active than ribavirin against HSV-2 in vitro, they are relatively more toxic to Vero cells. Compounds 3a and 20b exhibited moderate cytostatic activity against L1210 and P388 leukemia in vitro but are considerably less active than 2-chloro-2'-deoxyadenosine (1).