[Study on a new method for spectrophotometry]

In this paper, the relation between absorbance difference and concentration was measured by the ultraviolet spectrophotometer and computer made P-E company of U.S.A. The basic goal is to prove that the standard absorption curve method can be replaced by the new method, in which the sample was put in standard room and the standard material in sample room. Utilizing this method can minimize the error, most importantly, can measure the higher concentration sample, which can not be measured by the standard curve method. The new method does not require a Linear deltaA-c linear relationship.

Facile Routes to NiF(6)(2)(-), AgF(4)(-), AuF(6)(-), and PtF(6)(-) Salts Using O(2)(+) as a Source of O(2)F in Anhydrous HF

O(2)(+) salts dissolved in liquid anhydrous hydrogen fluoride (aHF) at 20 degrees C or below oxidize aHF solutions of PtF(6)(2)(-) to PtF(6)(-). The parent base of O(2)(+) salts in aHF (O(2)F((solv))) generated with alkali fluoride is long-lived below -50 degrees C. An aHF solution of O(2)F((solv)) oxidizes Au(III) to Au(V) below -50 degrees C (2O(2)F((solv)) + AuF(4)(-)((solv)) --> AuF(6)(-)((solv)) +2O(2(g))). In situ generation of O(2)F((solv)) (O(2)(+)((solv)) + F(-)((solv)) --> O(2)F((solv))) with AgF(2) or NiF(2) in suspension in the aHF made basic with alkali fluoride gives AgF(4)(-) and NiF(6)(2)(-)salts. Low solubility of AAsF(6)(A = Cs, K) in aHF provides for the metathetical preparation of (O(2))(2)PdF(6) solutions in aHF. Removal of aHF, even at -60 degrees C, results in some O(2) and F(2) loss, to a composition approaching (O(2))PdF(5).

Inhibition of methotrexate-induced rheumatoid nodulosis by colchicine: evidence from an in vitro model and regression in 7 of 14 patients

Methotrexate is one of the most effective and widely used medications in the treatment of rheumatoid arthritis. One poorly understood side effect of methotrexate is increased rheumatoid nodule formation, a phenomenon which has been reported to occur in some patients despite suppression of synovial inflammation. Using an in vitro model of nodulosis, induction of monocyte differentiation into multinucleated giant cells, we previously found that methotrexate promotes this inflammatory response by a mechanism dependent on adenosine A1 receptor stimulation. In the current study, we tested the effects of an A1 signal inhibitor, the commonly available anti-inflammatory medication colchicine, and found that it markedly inhibited nodulosis in vitro as well as in seven of fourteen patients in a clinical series.

DNA vaccination with the major outer-membrane protein gene induces acquired immunity to Chlamydia trachomatis (mouse pneumonitis) infection

The efficacy of DNA vaccination for prevention of Chlamydia trachomatis infection was studied using the murine model of pneumonia induced by the mouse pneumonitis (MoPn) isolate of C. trachomatis. Intramuscular DNA immunization with two chlamydial genes, one that encodes the major outer-membrane protein (MOMP) and one that encodes a cytoplasmic enzyme (cytosine triphosphate [CTP] synthetase) were tested. The MOMP DNA vaccine but not the CTP synthetase DNA vaccine generated significant delayed-type hypersensitivity and serum antibodies to MoPn elementary bodies and reduced the peak growth of MoPn by >100-fold following lung challenge infection. MOMP DNA immunization suggests a new approach to vaccine development for prevention of human chlamydial infection.

Photoelastic analysis of miniplate osteosynthesis for mandibular angle fractures

OBJECTIVE

The purpose of this study was to reassess Champy's findings, which were instrumental in justifying the theory of tension band plating for mandibular angle fractures.

STUDY DESIGN

Ten anatomically correct mandibles were fabricated with a photoelastic resin. In five mandibles, angle fractures were created and fixed with a superior border miniplate; five uncut mandibles served as controls. Each mandible was loaded in a manner that simulated physiologic conditions. The internal stress patterns were preserved within the models by completing a stress freezing cycle.

RESULTS

The stress patterns in the experimental mandibles virtually replicated the patterns seen in the controls. Stress fringes were present surrounding the outer screws, indicating that these screws were subjected to pull-out forces.

CONCLUSIONS

There is greater force on the outer screws that may contribute to fixation failure. The theory of tension band plating for mandibular angle fractures is accurate but Champy's model is oversimplified.

Structure-activity relationships for a novel series of pyrido[2,3-d]pyrimidine tyrosine kinase inhibitors

Screening of a compound library for inhibitors of the fibroblast growth factor (FGFr) and platelet-derived growth factor (PDGFr) receptor tyrosine kinases led to the development of a novel series of ATP competitive pyrido[2,3-d]pyrimidine tyrosine kinase inhibitors. The initial lead, 1-[2-amino-6-(2,6-dichlorophenyl)pyrido[2,3-d]pyrimidin-7-yl]-3- tert-butylurea (4b, PD-089828), was found to be a broadly active tyrosine kinase inhibitor. Compound 4b inhibited the PDGFr, FGFr, EGFr, and c-src tyrosine kinases with IC50 values of 1.11, 0.13, 0.45, and 0.22 microM, respectively. Subsequent SAR studies led to the synthesis of new analogs with improved potency, solubility, and bioavailability relative to the initial lead. For example, the introduction of a [4-(diethylamino)butyl]amino side chain into the 2-position of 4b afforded compound 6c with enhanced potency and bioavailability. Compound 6c inhibited PDGF-stimulated vascular smooth muscle cell proliferation with an IC50 of 0.3 microM. Furthermore, replacement of the 6-(2,6-dichlorophenyl) moiety of 4b with a 6-(3',5'-dimethoxyphenyl) functionality produced a highly selective FGFr tyrosine kinase inhibitor 4e. Compound 4e inhibited the FGFr tyrosine kinase with an IC50 of 0.060 microM, whereas IC50s for the inhibition of the PDGFr, FGFr, EGFr, c-src, and InsR tyrosine kinases for this compound (4e) were all greater than 50 microM.

Adenosine A1 receptor promotion of multinucleated giant cell formation by human monocytes: a mechanism for methotrexate-induced nodulosis in rheumatoid arthritis

OBJECTIVE

To determine why methotrexate (MTX) exacerbates rheumatoid nodules in some patients, despite the effective suppression of synovial inflammation.

METHODS

Phorbol myristate acetate (PMA)-induced differentiation of monocytes into multinucleated giant cells was used as an in vitro model to study the effects of adenosine on nodulosis.

RESULTS

MTX at 200-2,000 nM or the adenosine A1 agonist N5-cyclopentyl adenosine (CPA) (10(-12) to 10(-9) M) or the A2 antagonist 3,7-dimethyl-1-propargylxanthine markedly enhanced giant cell formation, whereas the adenosine A1 antagonist 8-cyclopentyl-dipropylxanthine completely reversed these effects. PMA, CPA, and MTX induced adenosine release by cultured monocytes at concentrations consistent with those associated with predominantly A1 effects. Furthermore, surface expression of A1 receptors was found to remain unchanged on the differentiating cells throughout the culture period.

CONCLUSION

Agents that inhibit adenosine A1 receptors might be useful in the treatment of MTX-induced rheumatoid nodulosis, while still potentiating the A2-mediated antiinflammatory effects of MTX on synovitis.

[A primary study of the association of human leucocyte antigen and osteosarcoma]

OBJECTIVE

To study the association of human leucocyte antigen and osteosarcoma in Chinese Han nationality.

METHODS

The frequencies of HLA-A,B,DR,DQ locus antigens were tested in a group of 25 osteosarcoma patients and in a control group of 250 healthy persons by using complement-dependent microlymphocytoxity technique. The members of both groups were of Chinese Han nationality. Their results were compared statistically.

RESULTS

The frequency of HLA-B35 was 0.400 in patient group and 0.048 in the control group. The relative risk of suffering from osteosarcoma in persons carrying HLA-B35 was 13.220 times as high as that in those without this antigen (P < 0.01). Patients with HLA-B13 had 12.048 fold increase in relative risk with poor prognosis compared to those without this antigen (P < 0.05). A tendency of worst prognosis was seen in patients who carried both HLA-B13 and HLA-B35, but patients with HLA-B40 had 7.057 times better relative safety for good prognosis than those without that antigen (P < 0.05).

CONCLUSION

HLA-B35 is in close linkage to osteosarcoma susceptible gene in Chinese Han nationality. HLA-B13 and HLA-B40 may be separately related to the malignant and resistant genes of osteosarcoma.

Experimental study on biodynamic response to vibration in human and animals

In order to study the characteristics of human dynamic response to vibration, 56 subjects were exposed to vibration on X, Y and Z axes. It showed that there were two resonance peaks of most local parts of the human body. The curves of transmissibility are essentially the same in all the subjects. It was found that resonance frequencies of the human body decreased with increase of G levels of vibration. These characteristics were also proved in animals. Using three-level artificial neural network, common reflective relation of the resonance frequency with height and weight of the human body and exciting acceleration were obtained. The above findings might be applicable to studies of vibration ergonomics.

High prevalence of antiphospholipid antibodies in patients taking procainamide

OBJECTIVE

To determine whether antiphospholipid antibodies (aPL) are more prevalent in cardiac patients taking procainamide than in a control population of similar elderly cardiac patients and to determine whether these antibodies react in an ELISA in which the primary antigen is beta 2-glycoprotein I (beta 2-GPI).

METHODS

aPL and antibodies to beta 2-GPI were measured in 66 patients taking procainamide from a Veterans Administration Medical Center population and a control group of 30 similar cardiac patients not taking procainamide.

RESULTS

21% of the patients taking procainamide and no control patients were found to have moderate to high aPL. There were similar results in an assay that measured anti-beta 2-GPI in the absence of exogenous phospholipids. aPL were associated with antinuclear antibodies and antihistone antibodies but not with diabetes or clinical manifestations of drug related lupus. There was no increase in cholesterol or past thrombotic history associated with aPL, but there was a frequent history of noncardiac thrombosis in patients taking procainamide (25.7%).

CONCLUSION

The predictive significance of procainamide induced aPL remains unknown but beta 2-GPI dependent aPL may be of some concern in this elderly population already at high risk for thrombosis.

Effect of magnesium sulfate on the development of cystic periventricular leukomalacia in preterm infants

To determine if magnesium sulfate has an effect on the development of cystic periventricular leukomalacia in preterm infants, this retrospective case control study was conducted. There were 23,382 infants born at three teaching hospitals in the metropolitan New York area from January 1992 to December 1994. Four hundred ninety-two infants met our entrance criteria. Criteria included a birth weight < 1750 g, survival to at least 7 days of life and at least one cranial ultrasound after 7 days of life. Infants exposed to magnesium sulfate in utero were less likely to develop periventricular leukomalacia. Two of 18 (11%) infants with periventricular leukomalacia were exposed to magnesium sulfate in-utero compared to 14 of 36 controls (39%) (p = 0.035) (OR = 0.196, 95% CI = 0.039-0.988). Pre-eclampsia as an independent factor was not associated with a reduced risk (p = 0.251) (OR = 0.294, 95% CI = 0.033-2.65). Preterm infants exposed to antenatal magnesium sulfate were found to have a reduced risk of developing cystic periventricular leukomalacia.

Characterization of zinc-substituted cytochrome c by circular dichroism and resonance Raman spectroscopic methods

Iron(III) in cytochrome c is replaced with zinc(II) by a modification of a method published by others, and the procedure is described in full detail. Three forms of cytochrome c-those containing iron(III), iron(II), and zinc(II)-are examined by circular dichroism spectroscopy and resonance Raman spectroscopy. Spectra of both kinds show that introduction of zinc(II) ions does not appreciably alter the overall structure and conformation of cytochrome c. Resonance Raman spectra indicate the size of the porphyrin "core" that is inconsistent with six-coordination and consistent with five-coordination. Unlike the iron(III) and iron(II) ions, which are bound to two axial ligands (His 18 and Met 80), the zinc(II) ion in cytochrome c seems to be bound to only one, most probably His 18. Evidence pertaining to the question of axial coordination is discussed.

Effects of mutations in plastocyanin on the kinetics of the protein rearrangement gating the electron-transfer reaction with zinc cytochrome c. Analysis of the rearrangement pathway

We study, by flash kinetic spectrophotometry on the microsecond time scale, the effects of ionic strength and viscosity on the kinetics of oxidative quenching of the triplet state of zinc cytochrome c (3Zncyt) by the wild-type form and the following nine mutants of cupriplastocyanin: Leu12Glu, Leu12Asn, Phe35Tyr, Gln88Glu, Tyr83Phe, Tyr83His, Asp42Asn, Glu43Asn, and the double mutant Glu59Lys/Glu60Gln. The unimolecular rate constants for the quenching reactions within the persistent diprotein complex, which predominates at low ionic strengths, and within the transient diprotein complex, which is involved at higher ionic strengths, are equal irrespective of the mutation. Evidently, the two complexes are the same. In both reactions, the rate-limiting step is rearrangement of the diprotein complex from a configuration optimal for docking to the one optimal for the subsequent electron-transfer step, which is fast. We investigate the effects of plastocyanin mutations on this rearrangement, which gates the overall electron-transfer reaction. Conversion of the carboxylate anions into amide groups in the lower acidic cluster (residues 42 and 43), replacement of Tyr83 with other aromatic residues, and mutations in the hydrophobic patch in plastocyanin do not significantly affect the rearrangement. Conversion of a pair of carboxylate anions into a cationic and a neutral residue in the upper acidic cluster (residues 59 and 60) impedes the rearrangement. Creation of an anion at position 88, between the upper acidic cluster and the hydrophobic patch, facilitates the rearrangement. The rate constant for the rearrangement smoothly decreases as the solution viscosity increases, irrespective of the mutation. Fittings of this dependence to the modified Kramers's equation and to an empirical equation show that zinc cytochrome c follows the same trajectory on the surfaces of all the plastocyanin mutants but that the obstacles along the way vary as mutations alter the electrostatic potential. Mutations that affect protein association (i.e., change the binding constant) do not necessarily affect the reaction between the associated proteins (i.e., the rate constant) and vice versa. All of the kinetic and thermodynamic effects and noneffects of mutations consistently indicate that in the protein rearrangement the basic patch of zinc cytochrome c moves from a position between the two acidic clusters to a position at or near the upper acidic cluster.

Glial cell-specific differences in repair of O6-methylguanine

Normal and malignant cells of the oligodendrocyte lineage show increased sensitivity to alkylating agents compared to astrocytes. One of the most mutagenic DNA lesions formed following exposure to alkylating agents is O6-alkylguanine. To determine whether the increased sensitivity to nitrosoureas seen in oligodendrocytes is due to decreased repair capacity for O6-alkylguanine, removal of this lesion from DNA was assessed in primary cultures of rat oligodendrocytes, astrocytes, and microglia. Glial cells were exposed to 1 mM N-methyl-N-nitrosourea for 1 h and allowed 8 or 24 h for repair. Repair was evaluated using an immunoslot blot technique and a monoclonal antibody which recognizes O6-methylguanine (O6MeGua). Astrocytes removed O6MeGua more efficiently (approximately 80% in 24 h) than either oligodendrocytes (approximately 20%) or microglia (approximately 4%). Determination of O6-alkylguanine-DNA-alkyltransferase (AT) activity revealed that astrocytes contain 0.4 pmol/mg protein, which is average by comparison to other cell types. Both oligodendrocytes and microglia exhibited very low levels of AT (oligodendrocytes, 0.08; microglia, 0.01 pmol/mg protein). These data are the first to show that within different populations of glial cells, O6MeGua adduct removal is substantially reduced in both oligodendrocytes and microglia. Rapid removal of O6MeGua in astrocytes coupled with persistence of this mutagenic lesion in oligodendrocytes following exposure of the developing central nervous system to nitrosoureas could contribute to the observed formation of oligodendrogliomas. Inefficient removal of O6MeGua in oligodendrogliomas might also account for their response to chemotherapeutic regimens involving alkylating agents such as procarbazine, lomustine, and carmustine. The lack of repair of O6MeGua in microglia suggests that primary lymphomas of the central nervous system might be sensitive to treatment with alkylating drugs whose toxicity depends on repair of this adduct.

[The angiographic classification and endovascular therapy of the vein of Galen aneurysmal malformation]

We treated 11 cases of the vein of Galen aneurysmal malformation, one of which was diagnosed by MRI only, and 10 underwent CAG diagnostic procedure. Among the 10 CAG diagnosed cases, 5 were classified as the vein of Galen aneurysmal malformation (VGAM) with the AV shunt directing to the vein of Galen. The other 5 were classified as the vein of Galen aneurysmal dilitation (VGAD) secondary to parenchymal AVM or dural AVF. 8 cases underwent endovascular treatment. For VGAM, the shunts in the wall of the vein were embolized. For VGAD, the primary AVM or AVF were embolized. The pathphysiology, angiographic characteristics, classification and the principle of endovascular therapy of the vein of Galen aneurysmal malformation were discussed.

Large-scale purification and characterization of recombinant fibroblast growth factor-saporin mitotoxin

In order to produce sufficient quantities of fibroblast growth factor-saporin (rFGF-2-SAP) mitotoxin for preclinical evaluation in models of diseases such as cancer and restenosis, we have undertaken the large-scale expression, purification, and characterization of the recombinant molecule. The fusion gene encoding rFGF-2-SAP was cloned into the inducible pET 11a expression vector and transformed into Escherichia coli strain BL21 (DE3). The transformants were grown using a fed-batch fermentation until the A600 reached 85. At this stage, induction of the expression of the fusion protein led to the production of approximately 2.2 mg/liter per A600 unit. The soluble mitotoxin was purified to homogeneity from cell lysates via expanded bed adsorption chromatography followed by cation-exchange, heparin-affinity, and size-exclusion chromatography. Purified rFGF-2-SAP contained less than 0.5 EU/mg of endotoxin, as determined by gel clot analyses. The highly purified rFGF-2-SAP retained the toxin's ability to inhibit protein synthesis as measured in a cell-free system and was cytotoxic to a number of normal and neoplastic cell lines bearing FGF receptors. Binding studies establish that the fusion protein exerts its effects via the FGF high-affinity receptor.

The epidemiology of Chlamydia trachomatis within a sexually transmitted diseases core group

Female sex workers in Nairobi were prospectively evaluated for risk factors of incident Chlamydia trachomatis infection. Independent risk factors included cervical ectopy (P=.007), gonococcal infection (P=.002), human immunodeficiency virus (HIV) seropositivity (P=.003), HIV seroconversion (P=.001), and duration of prostitution (P=.002). Eighteen different C. trachomatis outer membrane protein (omp1) genotypes were identified, with the allelic composition of the C. trachomatis population changing significantly over time (P=.005). Seventeen of 19 reinfections > or = 6 months apart were with different C. trachomatis omp1 genotypes. Women with HIV infection had an increased proportion of visits with C. trachomatis infection (P=.001) and an increased risk of reinfection (P=.008). Overall, the data demonstrate significant fluctuations in the genotype composition of the C. trachomatis population and a reduced rate of same-genotype reinfection consistent with the occurrence of strain-specific immunity.

Control of beta1 integrin function. Localization of stimulatory epitopes

The beta1 integrins can be expressed on the surface of cells in a latent form, which is activated by a variety of stimuli. As an approach to examining the transition to an active receptor, a panel of stimulatory antibodies to beta1 were produced and characterized. These antibodies induced adherence of the T-leukemic cell line Jurkat to collagen and fibronectin. Competitive antibody binding assays indicated the existence of at least three distinct epitope clusters A (B3B11, JB1B, 21C8), B (B44, 13B9), and C(N29) defined by the indicated antibodies. Two antibodies to the A site, JB1B and B3B11, were shown to localize to positions 671-703 and 657-670, respectively, of the beta1. This region is located in an area encompassing a predicted disulfide bond between linearly distant cysteines in beta1 (Cys415-Cys671). The homologous region of the beta3 integrin (490 690 and 602 690) has been shown to be one of the sites recognized by stimulatory antibodies to ligand-induced binding sites. The present results indicate the existence of multiple stimulatory regions and suggest considerable homology between the locations of beta1 and beta3 regulatory sites.

Local infusion of FGF-saporin reduces intimal hyperplasia

The recent conjugation of the potent ribosome-inactivating protein saporin (SAP) with basic fibroblast growth factor (FGF2) to form recombinant (r)FGF2-SAP permits increased selectivity of this mitoxin for cells exhibiting upregulated FGF receptors. Systemic administration of rFGF-SAP in therapeutic doses, however, may be associated with significant liver toxicity. In this blinded study, we used a local boundary layer infusion approach to increase local drug concentration while minimizing the risk of side effects. Six dogs underwent bilateral carotid endarterectomies. Expanded polytetrafluoroethylene infusion devices, blindly primed with rFGF2-SAP to one artery or vehicle to the contralateral vessel, were anastomosed proximal to the injured segments so that each animal served as its own control. rFGF2-SAP (2 microgram/kg/day) or vehicle (5 microl/hr) was continuously delivered for 14 days from an osmotic reservoir, through the wall of the graft infusion device. Euthanasia was carried out at 14 days and the processed arteries were blindly analyzed for intimal thickening and cellular proliferation. All dogs survived until sacrifice with no clinical side effects. Liver function tests at euthanasia were not significantly altered when compared to baseline values. Intimal area in rFGF2-SAP-treated vessels averaged 0.31 +/- 0.10 mm2 versus 0.57 +/- 0.24 mm2 in the control segments (P = 0.02), a relative reduction of 46%. Cell proliferation, however, was not significantly different at 14 days postendarterectomy (2.40 +/- 1.31% vs 2.39 +/- 0.45%). From this study it can be concluded that locally delivered rFGF2-SAP reduces intimal hyperplasia and that the boundary layer infusion strategy is an effective means for delivering high local drug concentration while minimizing systemic drug effects.

Synthesis and characterization of a homogeneous chemical conjugate between basic fibroblast growth factor and saporin

Basic fibroblast growth factor (FGF-2) and saporin were chemically conjugated using the crosslinker, N-succinimidyl-3(2-pyridyldithio)-propionate. When purified, the conjugate was found to be heterogeneous as analyzed by SDS/PAGE, size-exclusion HPLC and reverse-phase HPLC. Therefore, we sought to synthesize a molecule that would be homogeneous and thus easier to characterize and evaluate its efficacy and toxicity for pharmaceutical drug development. A homogeneous chemical conjugate was successfully synthesized by using a mutant FGF-2 with Cys96 replaced by Ser ([S96]FGF-2) and a recombinant saporin mutant containing a single Cys at the -1 position (C-SAP). The latter was expressed in Escherichia coli and isolated to 99% purity by expanded-bed adsorption chromatography followed by cation-exchange chromatography. The cysteine in C-SAP was activated by Ellman's reagent and then reacted with the only available cysteine (position 78) in [S96]FGF-2 to produce the homogeneous conjugate, designated as FGF2-C-SAP. The purified FGF2-C-SAP was more than 98% pure as judged by HPLC. In vitro biological assays indicated that FGF2-C-SAP was a potent inhibitor of protein synthesis in a cell-free system and was cytotoxic to FGF-receptor-bearing cells.

Selection of a gene for apolipoprotein A1 using autoantibodies from a patient with systemic lupus erythematosus

OBJECTIVE

To investigate immunoreactivity of systemic lupus erythematosus (SLE) sera with apolipoprotein A1, (Apo A1), the major lipid-binding protein of high-density lipoprotein (HDL).

METHODS

Since early attempts to identify Apo A1 autoantibodies using standard enzyme-linked immunosorbent assay (ELISA) and immunoblotting techniques had been unsuccessful, a mouse complementary DNA lambda phage expression library was screened.

RESULTS

A selected clone (MA1) was found to have 82% DNA sequence homology to a segment of human Apo A1. Since there were nonconservative substitutions in the MA1 protein and lack of a complete sequence, it was possible that the SLE patient's antibodies were binding MA1 epitopes that were shared by the complete human protein but had not been conformationally accessible using the earlier techniques. Thus, gamma-irradiated ELISA plates were used as an alternative antigen-binding surface for intact human Apo A1, and high-titer anti-human Apo A1 autoantibodies were then identified in the sera of 5 more SLE patients.

CONCLUSION

These findings show that Apo A1 is immunogenic. Apo A1 antibodies may play a role in the decreased HDL levels and Apo A1:Apo B ratios previously reported to occur in subgroups of SLE patients.

Influence of autonomic blockade and aging on AV conduction and responses to verapamil in the beagle

BACKGROUND

Age-related differences in responses to verapamil have been noted in both intact humans and isolated denervated perfused rat hearts. The study was designed to determine the effects of aging on intracardiac conduction and pharmacodynamic responses to verapamil, and also to determine the potential role of autonomic responses in previously reported age-related differences in responses to verapamil.

METHODS

After stability of measures was demonstrated in senescent animals, nine young (aged 3-4 years: 12.3 +/- 2.4 kg; 5 female, four male) and nine senescent (aged 8-11 years: 12.0 +/- 2.2 kg; 5 female, four male) beagles were randomized to undergo 60-minute verapamil infusions during pentobarbital anesthesia alone or after 1 mg/kg propranolol and 0.5 mg/kg atropine.

RESULTS

In the nonblocked state, verapamil increased A-A intervals (p < .001), P-R (p < .001), A-H intervals (p < .001), and AV Wenckebach block cycle length (p < .0001) and decreased blood pressure (p < .001) without age-related differences in responses. After autonomic blockade, heart rate and blood pressure decreased (p < .0001) and AV conduction intervals (p < .05) and AV Wenckebach block cycle length increased (p < .006). A-A intervals, A-H intervals, and AV Wenckebach block cycle length were significantly longer in senescent vs young beagles (559 +/- 87 vs 471 +/- 42 msec, p < .002; 103 +/- 6 vs 89 +/- 14, p < .05), 273 +/- 21 vs 238 +/- 26, p < .006, respectively). Verapamil effects on heart rate (p < .001) and AV conduction intervals (p < .007) and diastolic blood pressure (p < .003) were enhanced in younger, but not senescent, beagles after propranolol and atropine.

DISCUSSION

Verapamil produced similar effects on heart rate, blood pressure, and AV conduction in young and senescent beagles during barbiturate anesthesia. After double pharmacologic autonomic blockade, heart rate and AV conduction intervals and AV Wenckebach cycle length were significantly longer in senescent beagles when compared to younger beagles. Responses to verapamil after pharmacologic double autonomic blockade were enhanced only in younger beagles, suggesting greater contribution of reflex responses to results during verapamil infusions in the nonblocked state in younger animals.

Characterization of treated porcelain surfaces via dynamic contact angle analysis

Successful porcelain repair requires conditioning of porcelain surfaces. Conditioning is intended to facilitate wetting by repair materials and improve interfacial bonding. The objective of this investigation was to determine the effects of selected surface treatments upon the wettability of a representative feldspathic porcelain. Dynamic contact angle analysis and scanning electron microscopy were used to characterize the effects of such treatments. Standardized porcelain specimens were subjected to the following five treatment regimens: (1) control (no treatment); (2) airborne particle abrasion using 50 microns aluminum oxide; (3) etching with ammonium bifluoride gel; (4) etching with acidulated phosphate fluoride gel; and (5) etching with hydrofluoric acid gel. Following treatment, specimens were cleansed and dried. Advancing contact angles were quantified using dynamic contact angle analysis. Mean values and 95% confidence intervals were (in degrees): control, 63.8 +/- 2.7; ammonium bifluoride, 39.4 +/- 2.0; airborne particle abrading, 29.1 +/- 2.9; acidulated phosphate fluoride, 24.9 +/- 1.7; and hydrofluoric acid, 16.5 +/- 1.2. Significant differences were found between all treatment groups (P = .05). Subsequent scanning electron microscopy examination of treated surfaces indicated lesser contact angles were associated with surfaces displaying deeper and wider grooves. Apparently, the resultant increase in surface area produces increased wettability. It is inferred that an increase in surface area may correspond to enhanced resin-porcelain bonding.

[Specificity of the recombinant DNA pCX7 and its restriction enzyme map]

The recombinant DNA pCX7 derived from L. interrogans serovar lai strain 017 was applied for hybridization with 17 strains (8 serogroups of L. interrogans, L. biflexa strain Patoc I and Leptonema strain 3055); meanwhile 15 restriction endonucleases were used for analysis of the restriction enzyme map of pCX7. The result showed that the recombinant DNA probe is specific to species L. interrogans and its homology with DNA from different leptospires. A restriction enzyme map of pCX7 was constructed. Unique site for Bgl II and 3 sites for Bst BI were located within the cloned fragment (1.7 kb).

System for the pH-dependent release of a dye in model dental restorations

We are developing a system for detecting recurrent caries under dental restorations. The controlled release of dyes under conditions of likely demineralization will alert the dentist to potential secondary caries. Production of acidic species is a characteristic of caries activity; hence, the system uses pH-sensitive polymers to release markers when the pH at the cavity wall of the restored tooth is below 6.5. The objectives of this investigation were to test the hypotheses that (1) the proposed system can be designed to release detectable marker continuously for at least six months in a simulated carious environment, and (2) the transient pH changes in the oral cavity caused by simulated dietary intake will not induce premature marker release from the pH-sensitive polymer placed beneath restorations. Two types of dye-loaded microspheres based on styrene, vinylpyridine, and divinylbenzene were prepared and placed on the floor of model cavity preparations made from an acrylic rod. Each model cavity was restored with a hybrid dental composite, placed in a vial with 5 mL of sodium-lactate/lactic-acid base buffer solution, and stored at 37 degrees C. Solutions of three different pH values were used: 2.86, 4.73, and 6.39. The dye release into storage media was monitored periodically with a UV/VIS spectrophotometer. Results showed that the duration could extend beyond six months for pH > 4.73, and that transient oral pH changes are not likely to result in premature dye release. The data indicate that it would take approximately 21 days for the acidic agent external to the restoration to initiate dye release from restored sites.

Identification of pathogenic leptospires by recombinant DNA probes

Early diagnosis of leptospirosis of pulmonary diffuse hemorrhage type (PDH) is of crucial importance in saving patients. To develop a sensitive and specific method for diagnosis, a genomic library of the main pathogen of PDH, L. interrogans serovar lai strain 017, was constructed with the plasmid vector pUC9. Recombinant plasmids which have homologous fragments of pathogenic leptospires were screened from the bank. A recombinant plasmid, designated pCX7, could detect 1.7 kb fragment of strain 017, 9.0 kb of strain 601 and 30.0 kb of strain Hebdomadis, respectively, without cross hybridization with nonpathogenic leptospires such as L. biflexa strain Patoc I and Leptonema illini. The recombinant plasmid pCX7 could detect pathogenic leptospires which are the main pathogens endemic to Sichuan Province.

Sensitivity of catalyst/base ratio on curing of resin luting agents: polymerization exotherm analysis

OBJECTIVES

Currently, the proposed test of the International Standardization Organization (ISO) for measuring working and setting times of resin luting agents is based on measurement of times to reach specified stages on the polymerization exotherm. The objective of this study was to use this test to investigate the influence of variations in the mass ratios of catalyst paste to base paste on the working and setting times of three dual-cured dental resin luting agents.

METHODS

The materials used were Dicor Light Activated Cement (Dentsply International Inc.), Palfique Inlay Resin Cement (Tokuyama Soda Co.), and Vivadent Dual Cement (Vivadent). Fifteen specimens of each material were tested for working time by spatulating mass ratios from 0.7 to 1.3 for 30s at 23 degrees C and recording the time from beginning of spatulation to the time at which a temperature increase occurs. Ten specimens of each material were tested for setting time by spatulating in a similar manner at 37 degrees C and recording the time at which the temperature reaches a maximum value.

RESULTS

The data were fitted to the relation, In t = In A + Bm, where t is the time in seconds, m is the mass ratio, and A and B are regression coefficients. The results suggest that working and setting times of the specimens were independent of variations in mass ratio. A comparison among the materials was made by using a multiple linear regression with the relation, In t = In C + Dm + E gamma + Fm gamma, where gamma is a dummy variable to help distinguish between materials, and C, D, E, and F are regression coefficients. The results suggest that differences in materials influence the working time but not the setting time.

SIGNIFICANCE

These results infer that variations in mass ratio (+/- 20%) often observed in the clinical setting should not have a significant influence on the working and setting times of resin luting agents.

[Characterization of leptospiral DNA by southern hybridization serovar lai recombinant probe pCX7]

The recombinant probe pCX7, derived from genomic library of serovar lai strain 017, was applied for the characterization of DNA from 20 strains of leptospires in different genus species, sero-groups and serovars by southern hybridization. The probe, specific to partial species L. interrogans, did not hybridized with DNA of L. biflexa strain Patoc I and L. illini strain 3055, neither with DNA of serovars javanica, manhao 2 and ranarum which had shown very weak virulence, but hybridized with DNA of the other 15 strains of L. interrogans in 8 serogroups. It was easy to distinguish the banding patterns, since the pCX7 probe hybridized with a limited number of DNA fragments. Different leptospires showed different banding patterns. A few differences between strain 017 (strain of strong virulence) and strain 601 (strain of weak virulence) of serovar Lai were observed although their hybridization banding patterns were very similar. Differences in hybridization signals in combination with the banding pattern appear to provide good characteristics for identification of leptospiral serogroups and serovars, even strains. The result indicated that southern hybridization with the probe pCX7 might provide good tools for identification of leptospira.

The development of an instrument to measure self-consistency

The maintenance of self-consistency is a task that engages elderly people, and it can be viewed as an indicator of how well a person can cope with stress in the ageing process. However, there is no reliable and valid instrument to date that measures this phenomenon. To help elderly people to accomplish the task warrants the necessity to develop an instrument to measure self-consistency. The purpose of this study was to develop an instrument to measure self-consistency in elderly people with chronic conditions. The Self-Consistency Scale (SCS) was designed and administered to hearing-impaired elderly people (n = 130) in the north-east part of the USA. Psychometric properties of the SCS were evaluated and the results indicated a promising psychometric integrity. The obtained alpha coefficient for the SCS total scale was 0.89, with a score range of 51-104 and a mean total score of 85.10 (SD = 11.04). Convergent validity of the SCS was established by correlating the SCS to a Visual Analogue Scale--A Sense of Self (VAS), r = 0.60 (P < 0.01). Divergent validity with the Geriatric Depression Scale (GDS) was established, r = -0.57 (P < 0.01). Maximum likelihood factor analysis with oblimin rotation resulted in a two-factor solution: Factor I, self-knowledge; and Factor II, stability of self-concept.

Effect of hydration on the biaxial flexural strength of a glass ionomer cement

OBJECTIVES

The purpose of this study was to test the hypothesis that hydration during setting enhances the strength of glass ionomer cements.

METHODS

Thirty-four groups of eight disks each were prepared and sealed in nonpermeable bags to age for 30 min to 360 d before biaxial flexure testing. At each time interval, one group was tested immediately, while the second group was immersed in water for an additional 48 h prior to the same testing. Six of each group were used for strength testing and the remaining two were placed in a desiccator for determining evaporative water content with respect to initial weight.

RESULTS

A major portion of the disk strength developed within the first 2 wk and continued to improve at a much slower pace with time. Tukey's multiple range test indicated that additional 48 h immersion caused significant strength reduction for disks aged less than 30 d. The amount of weight loss in the desiccator decreased with aging time. The profiles of biaxial flexure strengths with respect to weight loss are similar for both groups. It infers that additional water storage introduces surface flaws that result in the strength reduction.

SIGNIFICANCE

Glass ionomer cement must be kept from direct water contact as long as possible to reach an acceptable level of strength.

Control of lymphocyte integrin function: evidence for multiple contributing factors

The control of lymphocyte adhesion is critical for proper cellular functions. The alpha 2 beta 1 integrin complex serves as a receptor for collagen on lymphocytes. The T cell leukemia Jurkat expresses alpha 2 beta 1 in a latent form on the cell surface. Three types of stimuli, antibody to the alpha 2 chain (JBS2), antibody to the beta 1 chain (JB1B), and phorbol ester (PMA), each induce activation of alpha 2 beta 1-dependent Jurkat binding to collagen. A comparison of the JBS2, JB1B, and PMA induction requirements indicated that the JB1B and the JBS2 effects are not sensitive to staurosporine while the PMA response is completely inhibited. Combinations of functionally saturating concentrations of the stimuli displayed an additive effect. Collectively these results suggest that several factors contribute to the generation of full integrin functionality and cellular adhesion, thus providing a possible basis for incrementally controlling the adhesive potential of lymphoid cells.

[Relative DNA content and cycle distribution of cells in pleural effusions studied by flow-cytometry]

Pleural effusions from 28 patients were studied by cytology, chromosome and flow-cytometry. Relative cellular DNA content was measured. An estimate of ploidy as well as cycle distribution has been given. Eighteen patients suffered from malignant effusions while the rest had TB effusions. 83.3% of malignant effusion had aneuploid. The relative cellular DNA content and the cell cycle distribution can provide valuable and decisive information. The study of chromosome also help the diagnosis in addition to cytological results.

Role of tumor necrosis factor in neonatal sepsis

In order to assess the role of tumor necrosis factor (TNF) in neonatal sepsis, plasma TNF levels were determined by a method using L929 cells at the time of septic work-up in 67 neonates. Thirty-three patients with sepsis were found to have significantly higher TNF levels (533.33 +/- 468.74 U/ml; 1 U corresponding to 1.67 pg recombinant TNF) as compared with 34 non-sepsis patients (100.0 +/- 188.97 U/ml) and 30 healthy newborns (27.33 +/- 16.17 U/ml, P < 0.05, respectively). The upper limit of normal plasma TNF levels was 60 U/ml and the best cutoff value for predicting neonatal sepsis was 160 U/ml. This had remarkable sensitivity (88%), specificity (82%), positive predictive value (83%), and negative predictive value (88%). Plasma TNF levels were significantly associated with the occurrence of shock, organ failure, scleroma and outcome. Thus, anti-TNF antibodies might be used in protecting newborns from septic death.

Induction of alpha v beta 3 integrin-mediated attachment to extracellular matrix in beta 1 integrin (CD29)-negative B cell lines

beta 1 integrin containing complexes have been implicated as the primary adhesion structures in many lymphocyte extracellular matrix (ECM) interactions. However, many B lymphocytes lack surface expression of the beta 1 subunit, implying that this subpopulation of lymphoid cells must employ alternate adhesion structures if they are to maintain an interactive capacity with ECM. An examination of the adherence properties of the beta 1 integrin-negative B cell line JY indicated that these cells exhibit little or no basal adherence to any of the ECM components examined. However, these cells could be induced to adhere to the ECM components fibronectin, laminin, and vitronectin following treatment with PMA. Blocking studies with monoclonal antibodies indicated the alpha v beta 3 integrin complex was involved in the attachment to each of these ligands. However, the adherence to fibronectin displayed a complex pattern of inhibition suggesting the involvement of other ECM receptors. The utilization of the alpha v beta 3 complex was not unique to the JY cell line. Other B cell lines were observed to employ alpha v beta 3, and these lines similarly lacked expression of beta 1 integrin. These results indicate that alpha v beta 3 can act as a lymphoid ECM-adhesion structure which may provide an alternative means for lymphocytes to interact with ECM. Furthermore, these studies provide evidence for the presence of lymphoid-associated alpha v beta 3 integrins with regulatable activity, which contrasts with the constitutive adhesive potential of these complexes when present on other cell types.

T1 and T2 of ferritin at different field strengths: effect on MRI

Nuclear magnetic relaxation times T1 and T2 were measured in ferritin solutions at field strengths from 0.04 to 1.5 T. T1 was relatively constant, but 1/T2 increased linearly with field strength, in agreement with earlier MRI observations in the monkey brain. This finding supports the theory that ferritin is responsible for T2 shortening in brain nuclei containing iron. The linear dependence of 1/T2 on magnetic field is unique and not explained by present theories of the magnetic properties of ferritin.

Effect of different sealers on thermoplasticized Gutta-percha root canal obturations

The objective of this study was to test the hypothesis that the apical seal provided by thermoplasticized root canal obturations depends on the film thickness of the sealer used. The root canals of 120 maxillary cuspid teeth were instrumented and divided into six equal groups of 20 teeth. A thermoplasticized gutta-percha root canal obturator was used to make an impression of the lubricated canal and coated with a sealer cement before reseating. Five different sealer cements of known film thickness were studied. They were, in the decreasing order of film thickness, Roth's Type I Cement, Seal-apex, Lee Endofil, AH26, and Ketac-Cem. The control group that received no sealer was prepared as recommended by the manufacturer. The degree of microleakage was based on the depth of dye penetration from the apical end measured by two independent examiners. The data collected were analyzed by analysis of variance and Weibull distribution. Analysis of variance shows that the control group exhibited significantly higher dye penetration depth (p < 0.05) while there were no significant differences among the other five groups. Analysis by Weibull distribution function shows that Lee Endofil and AH26 exhibited a higher percentage of lower linear dye penetration values compared with other groups.

Reactivity of gamma delta T cells induced by the tumour cell line RPMI 8226: functional heterogeneity of clonal populations and role of GroEL heat shock proteins

The human tumour cell lines RPMI 8226 and Daudi are potent inducers of V gamma 9-expressing T cells. The inducing element of RPMI 8226 has not been defined but evidence suggests that a member of the GroEL heat shock protein (HSP) family (HSP 58) may have a role in the induction by Daudi cells. The present study examined the reactivity patterns of gamma delta T-cell clones generated in response to RPMI 8226 and addressed the possible role of HSP 58 in this process. RPMI 8226 induced a population of V gamma 9 TCR+ cells which were heterogeneous in terms of their cell surface markers, patterns of proliferation and cytotoxic responses. All clones expressed CD3, CD2, CD18 and CD29. They demonstrated variability in expression of CD56, CD8 and HLA-DR. RPMI 8226 stimulated proliferation in purified bulk gamma delta cultures and clones. Daudi was also capable of inducing these cells to proliferate while mycobacterial products were not effective. The clones demonstrated a limited non-MHC-restricted cytotoxicity pattern with some evidence of clonal heterogeneity. Although both Daudi and RPMI 8226 were sensitive to lysis by the clones, cold inhibition experiments indicated differential activity towards these targets. Anti-HSP 58 was inhibitory to gamma delta T-cell induction by RPMI 8226, Daudi and mycobacterial products. However, the anti-HSP 58 antibody appears to bind to the surface of at least six different tumour cell lines with no correlation to their ability to induce gamma delta T cells and the anti-HSP 58 inhibited non-gamma delta responses.

Strengthening of feldspathic porcelain by ion exchange and tempering

This study investigated the effectiveness of tempering and ion-exchange treatments on crack growth and bi-axial flexural strength of seven feldspathic porcelains. The results showed that tempering treatment was more effective in strengthening porcelain than was the ion-exchange process as measured by the bi-axial flexural strength. However, the results of initial crack size induced by a microhardness tester showed that ion-exchange yielded a surface that was more resistant to crack initiation than was that yielded by the tempering treatment. EDX and microprobe analyses showed that there was evidence of exchange between Na+ within the porcelain surface and K+ from the ion-exchange agent applied on the surface.

Baseline fibrinolytic state and the risk of future venous thrombosis. A prospective study of endogenous tissue-type plasminogen activator and plasminogen activator inhibitor

BACKGROUND

Although isolated abnormalities of plasminogen activation and inhibition have been reported among selected patients with venous thrombosis, it is unclear whether these deficiencies of fibrinolysis are important risk factors for thromboembolic disease.

METHODS AND RESULTS

To evaluate whether baseline levels of endogenous tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor type 1 (PAI-1) predict the future occurrence of venous thrombosis, levels of these proteins were measured in prospectively collected plasma samples from 55 participants in the Physicians' Health Study who later developed deep venous thrombosis or pulmonary embolism and from an equal number of age- and smoking-matched control subjects who remained free of vascular disease during a mean follow-up period of 60.2 months. Overall, there were no statistically significant differences between case patients and control subjects in baseline levels of PAI-1 (50.5 versus 59.5 ng/ml, p = 0.26), t-PA (13.4 versus 13.3 ng/ml, p = 0.94), or PAI-1:t-PA ratio (6.84 versus 6.58, p = 0.82). No evidence of a threshold effect or trend was seen when these data were analyzed by increasing quartiles of PAI-1 (p = 0.73), t-PA (p = 0.62), or PAI-1:t-PA ratio (p = 0.93). These results were unchanged after multivariate analysis that simultaneously controlled for other baseline cardiovascular risk factors.

CONCLUSIONS

In contrast to previous uncontrolled case series and smaller retrospective studies, these prospective data provide strong evidence that baseline fibrinolytic state, as measured by t-PA and PAI-1, does not predict the occurrence of future venous thrombosis.