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Purpose of reviewAs our population ages, patients with arthritic basilar thumb joints will become an ever-increasing part of the practices of those treating hand problems. The gold standard for the surgical treatment of basilar thumb arthritis is the ligament reconstruction, tendon interposition art

Twelve cadaver extremities were used to study the effect of scaphoid and lunate facet depressions on the contact characteristics of the radiocarpal joint. Pressure-sensitive film was inserted into radiocarpal joints with varying degrees of depression, and the specimens were loaded statically in neutral position, radial deviation, and ulnar deviation. The film was removed and analyzed for contact area and pressure. The only statistically significant effect of a lunate fossa depression was an increase in scaphoid fossa pressure with a 3-mm step-off and the hand in neutral position. Scaphoid fossa depression had more significant effects. With a 1-mm scaphoid fossa depression, lunate fossa pressures increased in neutral position and in radial deviation. Lunate fossa contact area increased, compared to intact joints, in ulnar and radial deviation with 1-mm scaphoid fossa depressions and in all loading positions with 3-mm scaphoid fossa depression. Therefore, it appears that the most significant effect on radiocarpal joint contact characteristics occurs with a depression of the scaphoid side of the joint. Even with depressions as small as 1 mm, significant changes on the lunate side of the joint were observed.

Achieving satisfactory digital motion after suturing severed flexor tendons remains a challenge. Although a suture technique proposed by Savage is stronger in vitro than a true Kessler repair, the Savage technique has not been previously tested in vivo. We repaired 96 severed canine tendons using either of two modifications of the Kessler technique or the Savage technique. The tensile strength of these repairs were compared at 0, 1, 3, and 6 weeks after suturing. The Savage technique provided a significantly stronger repair than the "suture locking" method in vitro and at 1 and 3 weeks after repair. We found no significant differences between the tensile strengths of the Kessler-Tajima and suture-locking methods at any time.

Seventy-three patients were treated with either intrafocal pinning (Kapandji technique) alone or in combination with external fixation between 1988 and 1993 for extra-articular fractures of the distal radius (with or without a nondisplaced extension into the radiocarpal articular surface) with inadequate alignment after initial closed reduction. Sixty-one patients were available for follow-up examination at an average of 34 months (range, 24-71 months). The average age was 52 years (range, 16-84 years). Thirty-three of the patients were female. The patients all had dorsally displaced extra-articular fractures, although 56% had a nondisplaced extension of the fracture into the radiocarpal joint and 46% had a nondisplaced fracture extending into the distal radioulnar joint. The patients were separated into groups based on age, degree of comminution, and whether external fixation was also used. In the older patients, range of motion, grip strength, and pain relief were significantly better when external fixation was used, even when only 1 cortex of the radius demonstrated comminution. In the younger patients, good results in terms of range of motion, grip strength, and pain relief were obtained when percutaneous intrafocal pins were used alone in patients with comminution of only 1 surface of the radius (50% of the metaphyseal diameter). Whenor = 2 sides of the radial metaphysis were comminuted, the patients with external fixation had better results than those without external fixation. Although the correction of palmar tilt and radial tilt did result in better functional results, the restoration of radial length had the most significant effect on range of motion and grip strength.

A simple and efficient tantalum strip atomizer is described suitable for use in the atomic absorption determination of trace elements in water. The cell operates with an inexpensive Powerstat-transformer unit to provide the necessary electrothermal heat for atomization. It can be easily fitted in the place of the burner in atomic absorption instruments. The atomizer has been used to determine Ag, Cd, Pb, and Zn in tap water samples and Zn in the presence of albumin.

The electrochemical reduction of potassium ferrate(VI) in 6N-KOH occurs in three steps, at approximately +0.3, −0.7, and −1.4 V vs. Hg/HgO, 6N-KOH. The first reduction appears as a voltammetric wave on a platinum electrode and the second two are observed as polarographic waves with a dropping mercury electrode. Controlled potential coulometric, voltammetric, and chronopotentiometric studies indicate the reduction proceeds stepwise first to iron(III), then to iron(II) and finally to iron(0).

SUMMARY Todetermine theindependent influence oftheextentandsite ofresidual disease on late survival, we analyzed thefate of1448consecutive patients whohadcoronary arterybypass surgery during 1968-1974. There were 1274males, mean age53.4+ 8years(range 24-75years). Females were excluded fromfurther analysis. Twohundred twenty-six patients (17.7%) hadone-vessel disease, 492(38.6%)had two-vessel disease, 408(32.0%) hadthree-vessel disease and148(11.6%) hadleft mainstenosis. Survival was determined ata follow-up ofatleast 5years. Survival data wereanalyzed byKaplan-Meier survival curvesforthepatients withtwo-andthree-vessel disease according totheextent ofresidual disease. Forpatients withtwo-vessel disease andgoodventricular function, survival was similar at5years,89.1 % and87.7 % forno andone residual lesion; forthose with two-vessel disease andpoor ventricular function, 5-year survival was 84.5%and52.6%forno andone residual lesion; forthose withthree-vessel disease andgoodventricular function, itwas 92.0%,83.4 %, and 75.0 % forno,oneandtworesidual lesions, respectively. Withpoorventricular function, thecorresponding results were 83.1%,72.5%and23.1%. TheCoxmultivariate analysis technique was usedtoanalyze theinfluence ofage atoperation, numberof vessels diseased preoperatively, preoperative left ventricular function, period ofsurgery,andthenumber andsite ofresidual lesions after operation. Residual disease, ageatoperation andleft ventricular function werethemostimportant variables affecting survival ofpatients withtwo-andthree-vessel disease. Residual lesions oftheleft anterior descending orcircumflex coronaryarteries werethemostimportant predictors of survival; residual lesions oftheright coronaryartery exerted a lesser influence. Theresults ofthis study suggest thatthegreatest benefit intermsofimproved survival may come fromthefirst twotothree grafts placed. EARLYinourexperience withcoronary bypass, we observed, asdidothers, that operation inpatients with multivessel coronary disease appeared tohaveamore favorable outcome whenmultiple grafts wereplaced.'-' Thus, theconcept developed that ifall significant coronarylesions werebypassed, i.e., complete revascularization wasachieved, superior relief ofsymptoms and enhanced survival wouldresult. However, thevalidity ofthis concept isdifficult to prove, particularly withregard tosurvival. Incomplete revascularizatio n hasbeenmorelikely tooccurinpatients withother variables knowntoaffect survival adversely, suchasextensive multivessel coronary disease, which itself isassociated withhigher prevalence ofpoorleft ventricular function.7 Therefore, despite observations that suggest thebenefits ofcomplete revascularization,6 'analysis oftheinfluence ofresidual disease onsurvival according tothepresence orabsence ofresidual disease alone, without adjustment for other variables, maynotprovide anaccurate assessmentoftheinfluence ofresidual disease onsurvival. Furthermore, theinfluence ofresidual disease ofspecific vessels hasnotbeenexamined. Theaimofthisstudy wastodetermine whether

Acetylacetone extracts the lanthanides from aqueous solution at pH values between four and six. The solubility and extractability of the rare earth acetylacetonates vary with the ionic radii of the central metal ions. Extraction of the lanthanides with acetylacetone is enhanced by the decrease in basicity of the central metal ion. While separations based on differences in the pH 1 2 values of these chelates would be at best fractional, the variations in solubility and in the partition coefficients of these chelates make separations possible.

The synergistic effect of acetylacetone (Hacac) in the extraction of rare earth thenoyltrifluoroacetonates (Mtta3) was attributed to the formation of the species Mtta3 · Hacac. The adduct was isolated and identified by chemical analyses and i.r. spectra.

Chemical analyses, X-ray diffraction patterns, vapour-pressure studies and cryoscopic molecular weight determinations of nine rare-earth acetylacetonates prepared by conventional methods show that only two hydrates are formed: the monohydrate and the trihydrate. None of the conventional methods of preparation and drying yielded the anhydrous rare-earth acetylacetonates. Vapour pressure studies showed the formation of a solvate containing two moles of methanol per mole of chelate. Values of ΔH for the decomposition of the methanol disolvate indicate that the bond energy between the chelate and methanol is equivalent to strong hydrogen bonding. Solubility and cryoscopic molecular weight studies show that the chelates dissolve in benzene to form the monobasic compounds which polymerize, especially upon heating.

The acetylacetonates of the tervalent ions of aluminum, iron, chromium, scandium, gallium and indium form solvates containing one or two moles of halomethane. The formation of the solvates was studied by use of vapour-pressure-composition diagrams, and X-ray powder patterns. From a study of the vapour-pressure as a function of temperature and by use of the van't Hoff equation the value for the energy of the bond formation was calculated for each of seven halomethane solvates of aluminum, iron (III) and indium (III) acetylacetonates. The bonding (2–6 kcal/mole) is attributed to hydrogen bonding of the halomethane to the carbonyl oxygens of the acetylacetonate.

Several previously unreported adducts of rare earth acetylacetonates have been prepared and characterized by chemical analyses (including Karl Fischer titrations for water), i.r. spectra, and X-ray powder diffraction patterns. These adducts include compounds with methanol, ethanol, propanol, butanol, dioxane, pyridine, 2- and 4- methylpyridine, 2,4- and 2,6-dimethylpyridine, acetone, benzene, and acetylacetoneimine. Most of the adducts contain one or more moles of water per mole of chelate. It is concluded that when water and an organic donor are both present, only the water is coordinated to the rare earth ion and that the organic donor molecules are hydrogen-bonded or held in the crystal by lattice forces.

The countercurrent distribution behaviour of the rare-earth acetylacetonates in different solvent systems has been studied. Solubilities of the chelates in various solvents were determined in order to obtain data on the partition coefficients. The hydrated rare-earth acetylacetonates hydrolyze upon dissolving in benzene. Excess acetylacetone prevents hydrolysis and lowers the solubility of the chelates in the organic phase. A four-component system using acetylacetone, chloroform, methanol and water was developed. The acetylacetone in the chloroform phase suppressed hydrolysis and the methanol in the aqueous phase increased the solubilities of the chelates by a factor of ten over the solubilities in the water-acetylacetone system.

Rare-earth trishexafluoroacetylacetonates, Ln(hfac)3·nH2O, have been prepared and characterized by chemical analyses, infra-red spectra, and X-ray powder diffraction patterns. Two series of hydrates exist: Ln(hfac)3·3H2O (Ln = LaNd) and Ln(hfac)3·2H2O (Ln = LaLu). No evidence for a lower hydrate was found. A mixed ligand chelate, Ln(hfac)2CF3CO2·2H2O, is a byproduct of the tris chelate preparations. Several series of salts were also prepared, including NH4Ln (hfac)4·nH2O (n = 0 and 1 for Ln = LaNd; n = 0 for Ln = SmLu), pyHLn(hfac)4·nH2O (n = 0 and 1 for Ln = LnNd; n = 0 for Ln = SmLu), and (pyH)2Ln(hfac)5 (Ln = LaNd). Ln(hfac)3·3H2O. NH4Ln(hfac)4·H2O, and pyHLn(hfac)4·H2O are reversibly converted with great ease to Ln(hfac)3·2H2O, NH4Ln(hfac)4, and pyHLn(hfac)4, respectively. Most of the chelates studied are probably eight-co-ordinate, including Ln(hfac)3·3H2O, NH4Ln(hfac)4·H2O, and pyHLn(hfac)4·H2O, but (pyH)2Ln(hfac)5 may be ten-co-ordinate.

The synergistic extraction of the thenoyltrifluoroacetonates of neodymium, samarium, gadolinium, dysprosium, and erbium by acetylacetone was studied using mixtures of the two β-diketones. The synergistic shift of the extraction curves decreases the separability of the rare earth chelates.

• Over a 30-year period, 190 consecutive patients had repair of coarctation of the descending thoracic aorta at a mean age of 25 years (range, 1 to 60 years); 130 were male. Median preoperative blood pressure (BP) was as follows: systolic, 160 mm Hg (range, 94 to 300 mm Hg) and diastolic, 90 mm Hg (range, 50 to 160 mm Hg). Dacron grafts were used in 64.7% of patients. Follow-up was obtained at a mean interval of 84.9 months, range, one to 360 months. Survival status was established for 86.1% (163/190) of patients. Postoperatively, the median BP was 133 mm Hg systolic (range, 90 to 195 mm Hg) and 80 mm Hg diastolic (range, 50 to 120 mm Hg). Overall, 80% of patients were either normotensive or had mild hypertension after operation. The best BP response and late survival were in patients operated on under 13 years of age. This study further confirms that early operation (below 5 years of age) is desirable. However, contrary to some previous reports, patients operated on as adolescents, despite some mild residual hypertension, had an excellent long-term prognosis. Patients over 21 years of age at operation had a high rate of persistent hypertension and experienced other serious cardiovascular complications. ( Arch Surg 1981;116:1557-1560)

The electrochemical reduction of potassium ferrate(VI) in 6N-KOH occurs in three steps, at approximately +0.3, −0.7, and −1.4 V vs. Hg/HgO, 6N-KOH. The first reduction appears as a voltammetric wave on a platinum electrode and the second two are observed as polarographic waves with a dropping mercury electrode. Controlled potential coulometric, voltammetric, and chronopotentiometric studies indicate the reduction proceeds stepwise first to iron(III), then to iron(II) and finally to iron(0).