In vitro changes in clips and bars used to retain implant overdentures

Although implant-retained overdentures are a less expensive alternative to fixed implant-supported prostheses in certain situations, problems with retentive clips fracturing and needing frequent replacement have been reported. This study compared baseline and posttest retention of metal and plastic clip-retained overdenture analogs and monitored surface changes in bars and clips throughout the testing process. A laboratory model was made with two implant analogs processed into an acrylic resin platform to which three bars were fitted. Two overdenture analogs were made and retained on the model with metal or plastic clips. Each bar-clip assembly was subjected to 5500 insertion and removal cycles to simulate 3 years of in vivo insertion and removal. Although the differences in retention between metal and plastic clips and between clips before and after testing were statistically significant, it is questionable whether they are clinically significant. Neither clip fracture nor loss occurred during this study, which suggests that it may be functional or parafunctional loading and not repeated insertion and removal of an implant overdenture that may cause the stated problems.     

Detection of anti-topoisomerase I antibodies using a full length human topoisomerase I recombinant protein purified from a baculovirus expression system

Topoisomerase I (topo I) is a major systemic sclerosis (SSc)-associated autoantigen. A cDNA construct encoding full length human topo I in a recombinant baculovirus transfer vector was used to infect insect cells in culture from which recombinant protein was purified. An ELISA using recombinant protein was evaluated in 340 sera including sera from 134 patients with SSc, of whom 33 had anti-topo I antibodies detected by immunodiffusion. A high yield of pure topo I of expected molecular mass and catalytic activity was obtained. The recombinant topo I ELISA was 92% sensitive and 98% specific in detecting anti-topo I antibodies which were present almost exclusively in patients with SSc. Therefore, the potential advantages of expressing human autoantigens in eukaryotic systems for diagnostic purposes were confirmed.     

Left ventricular diastolic function in young adults: the Coronary Artery Risk Development in Young Adults Study

Shiga-like toxin type I (SLT-I) is a cytotoxin produced by certain strains of Escherichia coli. SLT-I is a bipartite molecule comprised of A (SLT-IA) and B (SLT-IB) subunits. In holotoxin, five B subunits are arranged in a pentameric ring and bind to globotriaosylceramide receptors on the surface of susceptible eukaryotic cells. The SLT-IB pentamer is noncovalently associated with one A subunit that has N-glycosidase activity and ultimately causes the death of targeted cells. Using a previously described overexpression vector, plasmid SBC32, we developed a two-step procedure for the purification of biologically active recombinant SLT-IB. Periplasmic proteins were extracted from E. coli JM105(pSBC32), fractionated by ammonium sulfate precipitation, and separated by isoelectric focusing in a pH 3-10 gradient. SLT-IB was present in fractions with pH values between 5.0 and 6.0, consistent with its reported pI of 5.8. SLT-IB was purified to homogeneity in a second step by native polyacrylamide gel electrophoresis. Purified SLT-IB was characterized for biological and biochemical activity. When analyzed by native polyacrylamide gel electrophoresis, the majority of SLT-IB had an apparent molecular weight of 38,900, consistent with a pentameric subunit association. Chemical cross-linking of SLT-IB with disuccinimidyl suberate resulted in species with molecular weights corresponding to dimeric, trimeric, tetrameric, and pentameric forms of B subunit. SLT-IB was not cytotoxic to Vero cells at concentrations as high as 10 micrograms/ml and protected Vero cells from native SLT-I. Purified SLT-IB maintained its ability to associate with SLT-IA to form holotoxin that exhibited toxicity similar to native toxin.     

Some corrections of coccidian (Apicomplexa: Protozoa) nomenclature

The following nomenclatural corrections and changes are introduced for the coccidia. NEW SPECIES: Cryptosporidium rhesi from the rhesus monkey Macaca mulatta; Cryptosporidium serpentis from the snakes Elaphe guttata, Elapha subocularis, Crotalus horridus, and Sanzinia madagascarensis; Eimeria perazae from the lizard Cnemidophorus l. lemniscatus; and Eimeria tarichae from the salamander Taricha toirosa. NEW COMBINATIONS: Orcheobius carinii for Cariniella carinii from the frog Leptodactylus ocellatus; Schellackia iguanae for Lainsonia iguanae from the iguana Iguana iguana; Schellackia weinbergi for Haemogregarina weinbergi from the lizard Tupinambis nigropunctatus; Dorisa harpia for Dorisiella harpia from the bat Harpiocephalus harpia lasyurus; Barrouxia labbei for Echinospora labbei from the centipedes Lithobius mutabilis and L. pyrenaicus; and Barrouxia ventricosa for Echinospora ventricosa from the centipede Lithobius hexodus. The generic names Lainsonia and Gordonella are synonymized with Schellackia; Echinospora with Barrouxia; and Cariniella with Orcheobius.     

Retinal emboli in patients with mitral valve prolapse

Small fibrin-platelet emboli caused by prolapsed mitral valves may cause retinal occlusive disease with a wide range of ophthalmic manifestations, including amaurosis fugax in young people, retinal or choroidal arteriolar occlusion, and retinal neovascularization (atypical Eales' disease). Six patients with retinal occusive disease underwent extensive noninvasive cardiac and systemic tests and were found to have prolapsed mitral valves. Patients with unexplained ocular emboli should be examined by a cardiologist for possible mitral valve prolapse.     

A functional analysis of imprinting in parthenogenetic embryonic stem cells

A detailed analysis of the developmental potential of parthenogenetic embryonic stem cells (PGES) was made in vivo and in vitro, and a comparison was made with the development of cells from parthenogenetic embryos (PG). In vivo, in chimeras with normal host cells (N), PGES cells showed a restricted tissue distribution consistent with that of PG cells, suggesting faithful imprinting in PGES cells with respect to genes involved in lineage allocation and differentiation. Restricted developmental potential was also observed in teratomas formed by ectopic transfer under the kidney capsule. In contrast, the classic phenotype of growth retardation normally observed in PG<==>N chimeras was not seen, suggesting aberrant regulation in PGES cells of genes involved in growth regulation. We also analysed the expression of known imprinted genes after ES cell differentiation. Igf2, H19 and Igf2r were all appropriately expressed in the PGES derived cells following induction of differentiation in vitro with all-trans retinoic acid or DMSO, when compared with control (D3) and androgenetic ES cells (AGES). Interestingly, H19 was found to be expressed at high levels following differentiation of the AGES cells. Due to the unexpected normal growth regulation of PGES<==>N chimeras we also examined Igf2 expression in PGES derived cells differentiated in vivo and found that this gene was still repressed. Our studies show that PGES cells provide a valuable in vitro model system to study the effects of imprinting on cell differentiation and they also provide invaluable material for extensive molecular studies on imprinted genes. In addition, the aberrant growth phenotype observed in chimeras has implications for mechanisms that regulate the somatic establishment and maintenance of some imprints. This is of particular interest as aberrant imprinting has recently been invoked in the etiology of some human diseases.     

A multifactorial trial design to assess combination therapy in hypertension. Treatment with bisoprolol and hydrochlorothiazide

BACKGROUND: The safety and effectiveness of different dosages and combinations of antihypertensive agents can be efficiently studied using a multifactorial trial design. In consultation with the Cardio-Renal Division of the Food and Drug Administration, we conducted a randomized, double-blind, placebo-controlled, 3 x 4 factorial trial of bisoprolol, a beta 1-selective adrenergic blocking agent, and hydrochlorothiazide. METHODS: A total of 512 patients with mild to moderate essential hypertension were randomized to once-daily treatment with bisoprolol (0, 2.5, 10, or 40 mg), hydrochlorothiazide (0, 6.25, or 25 mg), and all possible combinations. Diastolic and systolic blood pressures were monitored during this 12-week trial. RESULTS: The effects of bisoprolol and hydrochlorothiazide were additive with respect to reductions in diastolic and systolic blood pressures over the dosage ranges studied. The addition of hydrochlorothiazide (or bisoprolol) to therapy with bisoprolol (or hydrochlorothiazide) produced an incremental reduction in blood pressure. Dosages of hydrochlorothiazide as low as 6.25 mg/d contributed a significant antihypertensive effect. A hydrochlorothiazide dosage of 6.25 mg/d produced significantly less hypokalemia and less of an increase in uric acid levels than a dosage of 25 mg/d. The low-dose combination of bisoprolol, 2.5 mg/d, and hydrochlorothiazide, 6.25 mg/d, reduced diastolic blood pressure to lower than 90 mm Hg in 61% of patients and demonstrated a safety profile that compared favorably with that of placebo. CONCLUSIONS: The utility of factorial design trials to characterize dose-response relationships and to test the potential interactions between various antihypertensive agents has been demonstrated. The combination of low dosages of bisoprolol and hydrochlorothiazide may be a rational alternative to conventional stepped-care therapy for the initial treatment of patients with mild to moderate hypertension.     

Using time intervals between expected events to communicate risk magnitudes

Choledochal cyst is a rare pathology in western countries and the typical signs and symptoms are not always present at the onset. The diagnosis is often difficult and it needs a long time to be clear. In this paper we review our recent experience with this pathology (8 patients) and particularly we point out the problems of the delate in the diagnosis and the best choice to study these patients.     

Ab initio quantum mechanical and X-ray crystallographic studies of gemcitabine and 2''-deoxy cytosine

Thirty-seven of 41 consecutive patients with recurrent anterior instability of the shoulder were retrospectively observed for a mean of 5.6 years (range, 4 to 10) after an arthroscopic stabilization procedure had been performed. The operative technique involved the use of transglenoid sutures to repair the capsule and labrum. According to the criteria established by Rowe, 27 patients (74%) had good or excellent results, and 3 patients (7%) were graded as fair. Seven patients (19%) developed recurrent instability after the procedure and had failed results. Failure rates were equal in patients with a history of recurrent dislocation and those with recurrent subluxation. Absence of a Bankart lesion at operation was associated with postoperative instability (P = 0.03). The presence or size of humeral head defects did not influence the result. Eight of 12 athletes who engaged in sports requiring repetitive overhead shoulder motion returned to full activity, and none of the 12 developed instability after operation. Four of the 13 patients who participated in contact sports or recreational skiing developed postoperative instability (P = 0.21). All failures occurred within 2 years of the procedure.