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Akamatsu, N., H. Nakajima, M. Ono, and Y. Miura, "Increase in acetyl CoA synthetase activity after phenobarbital treatment.", Biochemical pharmacology, vol. 24, issue 18, pp. 1725-7, 1975 Sep 15. Abstract
Anderson, T. R., and T. A. Slotkin, "Maturation of the adrenal medulla--IV. Effects of morphine.", Biochemical pharmacology, vol. 24, issue 16, pp. 1469-74, 1975 Aug 15. Abstract
Asakura, T., K. Adachi, M. Shapiro, S. Friedman, and E. Schwartz, "Mechanical precipitation of hemoglobin köln.", Biochimica et biophysica acta, vol. 412, issue 2, pp. 197-201, 1975 Dec 15. Abstract

Hb Köln (beta 98 Val leads to Met) was found to precipitate rapidly during mechanical shaking. The rate of precipitation of Hb Köln is 5-6 times faster than that of Hb S. The kinetics of precipitation of the patient's hemolysate, which is a mixture of Hb Köln and Hb A, showed a biphasic curve indicating that Hb Köln precipitates independently from Hb A. The instability of Hb Köln may be attributed to the conformational change in the vicinity of heme. The mechanical shaking may be used as a new method for detection and quantitation of hemoglobin Köln and other unstable hemoglobins.

Baccanari, D., A. Phillips, S. Smith, D. Sinski, and J. Burchall, "Purification and properties of Escherichia coli dihydrofolate reductase.", Biochemistry, vol. 14, issue 24, pp. 5267-73, 1975 Dec 2. Abstract

Dihydrofolate reductase has been purified 40-fold to apparent homogeneity from a trimethoprim-resistant strain of Escherichia coli (RT 500) using a procedure that includes methotrexate affinity column chromatography. Determinations of the molecular weight of the enzyme based on its amino acid composition, sedimentation velocity, and sodium dodecyl sulfate gel electrophoresis gave values of 17680, 17470 and 18300, respectively. An aggregated form of the enzyme with a low specific activity can be separated from the monomer by gel filtration; treatment of the aggregate with mercaptoethanol or dithiothreitol results in an increase in enzymic activity and a regeneration of the monomer. Also, multiple molecular forms of the monomer have been detected by polyacrylamide gel electrophoresis. The unresolved enzyme exhibits two pH optima (pH 4.5 and pH 7.0) with dihydrofolate as a substrate. Highest activities are observed in buffers containing large organic cations. In 100 mM imidazolium chloride (pH 7), the specific activity is 47 mumol of dihydrofolate reduced per min per mg at 30 degrees. Folic acid also serves as a substrate with a single pH optimum of pH 4.5. At this pH the Km for folate is 16 muM, and the Vmax is 1/1000 of the rate observed with dihydrofolate as the substrate. Monovalent cations (Na+, K+, Rb+, and Cs+) inhibit dihydrofolate reductase; at a given ionic strength the degree of inhibition is a function of the ionic radius of the cation. Divalent cations are more potent inhibitors; the I50 of BaCl2 is 250 muM, as compared to 125 mM for KCl. Anions neither inhibit nor activate the enzyme.

Bhagwat, V. M., and B. V. Ramachandran, "Malathion A and B esterases of mouse liver-I.", Biochemical pharmacology, vol. 24, issue 18, pp. 1713-7, 1975 Sep 15. Abstract
Bland, R. D., T. L. Clarke, and L. B. Harden, "Rapid infusion of sodium bicarbonate and albumin into high-risk premature infants soon after birth: a controlled, prospective trial.", American journal of obstetrics and gynecology, vol. 124, issue 3, pp. 263-7, 1976 Feb 1. Abstract

We conducted a controlled, prospective trial to evaluate the effectiveness of rapidly infusing sodium bicarbonate (NaHCO3) and salt-poor albumin into high-risk, premature infants in the first 2 hours of life. Fifty-three infants, randomized into one of four treatment groups, received 8 ml. per kilogram of a solution containing either (A) glucose in water, (B) salt-poor albumin, (C) NaHCO3, or (D) a combination of albumin and NaHCO3. After the initial infusion, the babies received no colloid or alkali solutions until 4 hours of age. We managed them supportively with warmth, appropriate oxygen administration, isotonic fluid infusion, and close monitoring. Among the infants who received alkali, 14 of 26 acquired the respiratory distress syndrome (RDS), 11 died, and four had intracranial hemorrhage. Among babies who received no alkali, RDS occurred in 11 of 27, 5 died, and none had intracranial hemorrhage. These results do not support the common practice of rapidly infusing NaHCO3 into high-risk, premature infants, and they suggest that the early management of such infants needs renewed critical evaluation.

Buchet, R., L. Beauvais, and C. Sandorfy, "Hydrogen bond equilibrium constants of some unusual nucleotide base pairs.", Journal of biomolecular structure & dynamics, vol. 2, issue 1, pp. 221-32, 1984 Aug. Abstract

Approximate hydrogen bond association constants were determined for base pairs formed by an adenine derivative and a number of unusual pyrimidine bases. A series is found in which the H-bond strength in the base-pairs varies. In certain cases the H-bond equilibrium constant is larger than in the adenine-thymine pair. Inosine derivatives seem to have a non-negligible chance of replacing guanosine in the guanosine-cytosine pair. Infrared, near-infrared (overtone) and NMR spectra were used to determine the equilibrium constants.

Chow, Y. W., R. Pietranico, and A. Mukerji, "Studies of oxygen binding energy to hemoglobin molecule.", Biochemical and biophysical research communications, vol. 66, issue 4, pp. 1424-31, 1975 Oct 27. Abstract
Coscia, L., P. Causa, E. Giuliani, and A. Nunziata, "Pharmacological properties of new neuroleptic compounds.", Arzneimittel-Forschung, vol. 25, issue 9, pp. 1436-42, 1975 Sep. Abstract

RMI 61 140, RMI 61 144 and RMI 61 280 are newly synthetized N-[8-R-dibenzo(b,f)oxepin-10-yl]-N'-methyl-piperazine-maleates which show interesting psychopharmacologic effects. This work contains the results of a study performed with these three compounds, in order to demonstrate their neuropsycholeptic activity in comparison with chloropromazine (CPZ) and chlordiazepoxide (CPD). The inhibition of motility observed in mice shows that the compounds reduce the normal spontaneous motility as well as the muscle tone. The central-depressant activity is evidenced by increased barbiturate-induced sleep and a remarkable eyelid ptosis can also be observed. Our compounds do not show any activity on electroshock just as do CPZ and CPD. As to the antipsychotic outline, our compounds show strong reduction of lethality due to amphetamine in grouped mice and a strong antiapomorphine activity. They show also an antiaggressive effect and an inhibitory activity on avoidance behaviour much stronger than CPZ. We have also found extrapyramidal effects, as catalepsy, common to many tranquillizers of the kind of the standards used by us. As for vegetative phenomena, the compounds show hypotensive dose related action ranging from moderate to strong, probably due to an a-receptor inhibition. Adrenolytic activity against lethal doses of adrenaline, antiserotonin and antihistaminic effects, as well as other actions (hypothermia, analgesia, etc.) confirm that RMI 61 140, RMI 61 144 and RMI 61 280 are endowed with pharmacologic properties similar and more potent than those of CPZ. Studies on the metabolism of brain catecholamines show that they are similar to CPZ, although with less effect on dopamine level.

Crow, T. J., J. F. Deakin, and A. Longden, "Proceedings: Do anti-psychotic drugs act by dopamine receptor blockade in the nucleus accumbens.", British journal of pharmacology, vol. 55, issue 2, pp. 295P-296P, 1975 Oct. Abstract
Dzudza, D., "[Chronic adhesive spinal arachnoiditis].", Medicinski arhiv, vol. 38, issue 6, pp. 291-6, 1984. Abstract
Elkhadem, A., and S. Wanees, "Limited evidence suggests standard fluoride toothpaste reduces caries potential in preschool children.", Evidence-based dentistry, vol. 15, issue 1, pp. 5, 2014 Mar. Abstract

DATA SOURCES: CENTRAL, Medline, Embase, Web of Science, LILACS and BBO databases, the Brazilian database of thesis and dissertations (Banco de Teses CAPES), a Brazilian register of ethically approved projects involving human beings (SISNEP) and two registers of ongoing trials (Current Controlled Trials and Reference lists were also scanned for relevant papers. Study authors were contacted for additional information.

STUDY SELECTION: Individual or cluster-randomised or quasi-randomised controlled trials conducted in children under seven were included.

DATA EXTRACTION AND SYNTHESIS: Study selection and data abstraction were conducted by two reviewers independently. Risk of bias assessment was undertaken using the Cochrane Collaboration tool. Meta-analyses of prevented fractions (PF) were performed to assess the effect of fluoride toothpaste on the dmft and dmfs. Meta-analyses were also performed to obtain a pooled relative risk (RR) to assess the effect of fluoride toothpastes on the proportion of children developing caries.

RESULTS: Eight studies were included. When standard F toothpastes were compared to placebo or no intervention, significant caries reduction at surface (PF = 31%; 95% CI 18-43; 2644 participants in five studies), tooth (PF = 16%; 95% CI 8-25; 2555 participants in one study) and individual (RR = 0.86; 95% CI 0.81-0.93; 2806 participants in two studies) level were observed. Low F toothpastes were effective only at surface level (PF = 40%; 95% CI 5-75; 561 participants in two studies).

CONCLUSIONS: Standard F toothpastes are effective in reducing dental caries in the primary teeth of preschool children and thus their use should be recommended to this age group.

Elkhadem, A., and I. Sami, "No clear evidence of superiority regarding pulp medicaments in primary molars.", Evidence-based dentistry, vol. 15, issue 4, pp. 100-1, 2014 Dec. Abstract

DATA SOURCES: Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase, the Web of Science, OpenGrey, the US National Institutes of Health Trials Register and the World Health Organization (WHO) Clinical Trials Registry Platform.

STUDY SELECTION: Two reviewers independently selected studies. Randomised controlled trials comparing different pulp interventions combining a pulp treatment technique and a medicament in primary teeth were considered.

DATA EXTRACTION AND SYNTHESIS: Data abstraction and risk of bias assessment were carried out independently by two reviewers. The primary outcomes were clinical failure and radiological failure, as defined in trials, at six, 12 and 24 months. Pairwise meta-analysis using fixed-effect models was conducted with statistical heterogeneity being assessed using I2 coefficients.

RESULTS: Forty-seven trials involving 3910 teeth were included. All were small single centre studies. The overall level of evidence was low with only one trial having a low risk of bias, 20 a high risk and 26 unclear risk of bias.The 47 trials examined 53 different comparisons: 25 for pulpotomy, 13 for pulpectomy, 13 for direct pulp capping and two comparisons between pulpotomy and pulpectomy.Regarding pulpotomy, 14 trials compared mineral trioxide aggregate (MTA) with formocresol (FC). MTA reduced both clinical and radiological failures at six, 12 and 24 months, although the difference was not statistically significant. MTA also showed favourable results for all secondary outcomes measured, although again, differences between MTA and FC were not statistically significant (with the exception of pathological root resorption at 24 months and dentine bridge formation at six months). MTA showed favourable results compared with calcium hydroxide (CH) (two trials) for all outcomes measured, but the differences were not statistically significant (with the exception of radiological failure at 12 months). When comparing MTA with ferric sulphate (FS) (three trials), MTA had statistically significantly fewer clinical, radiological and overall failures at 24 months. This difference was not shown at six or 12 months.FC was compared with CH in seven trials and with FS in seven trials. There was a statistically significant difference in favour of FC for clinical failure at six and 12 months, and radiological failure at six, 12 and 24 months. FC also showed favourable results for all secondary outcomes measured, although differences between FC and CH were not consistently statistically significant across time points. The comparisons between FC and FS showed no statistically significantly difference between the two medicaments for any outcome at any time point.For all other comparisons of medicaments used during pulpotomies, pulpectomies or direct pulp capping, the small numbers of studies and the inconsistency in results limits any interpretation.

CONCLUSIONS: We found no evidence to identify one superior pulpotomy medicament and technique clearly. Two medicaments may be preferable: MTA or FS. The cost of MTA may preclude its clinical use and therefore FS could be used in such situations. Regarding other comparisons for pulpectomies or direct pulp capping, the small numbers of studies undertaking the same comparison limits any interpretation.

Elkhadem, A., "Large overjet may double the risk of dental trauma.", Evidence-based dentistry, vol. 16, issue 2, pp. 56, 2015 Jun. Abstract

DATA SOURCES: Medline/PubMed, SCOPUS and Google Scholar.

DATA EXTRACTION AND SYNTHESIS: Studies were split according to the type of teeth and the overjet threshold used, thus obtaining three subsets; primary teeth - overjet threshold 3-4 mm; permanent teeth - overjet threshold 3-4 mm and permanent teeth - overjet threshold 6 ± 1 mm. Pooled odds ratios for TDI were estimated for each dataset.

RESULTS: Fifty-four studies were included involving patients from five continents. The adjusted pooled odds ratios were 2.31 (95%CI; 1.01-5.27) for primary teeth with 3-4 mm overjet; 2.01 (95%CI; 1.39-2.91) for permanent teeth with 3-4 mm overjet and 2.24 (95%CI; 1.56-3.21) for permanent teeth with 6 ± 1 mm overjet.

CONCLUSIONS: The present meta-analysis of observational studies showed that large overjet may double or even triple the risk for TDI to anterior primary and permanent teeth and that, at global level, large overjet is partly responsible for 100-300 million TDIs.

Elkhadem, A., and S. Wanees, "Socioeconomic indicators and traumatic dental injury.", Evidence-based dentistry, vol. 16, issue 4, pp. 120-1, 2015 Dec. Abstract

Data sourcesPubMed, ISI, LILACS, Cochrane Library and Embase databases were searched.Study selectionEpidemiological studies (cross-sectional, case-control, cohort clinical trials) addressing possible associations between socioeconomic indicators (eg mother's schooling, household income, number of children, type of school) and traumatic dental injury in the primary dentition were considered.Data extraction and synthesisTwo reviewers independently selected studies. with study quality being assessed using the Newcastle-Ottawa Scale (NOS). Data were extracted for categorical variables considered risk factors for TDI and recorded based on the distribution and frequency of TDI among children exposed to risk factors vs the frequency among children not exposed to risk factors. Meta-analysis was undertaken.ResultsSixteen studies (15 cross-sectional studies and one cohort study) were included. A wide range of socioeconomic indicators were investigated including; parents' schooling, parents' employment status, home ownership, having changed address in the previous year, income, family structure, number of residents in the home, number of children in the family, type of school and socioeconomic status. Children from families with household income less than two times average salary (US$ 592) (OR: 0.77; 95% CI: 0.66-0.90) or more than three times the average salary (US$ 888) (OR: 0.76; 95% CI: 0.65-0.89) had a significantly lower chance of having TDI in the primary dentition. TDI was not associated with socioeconomic status (high vs low - OR: 0.77; 95% CI: 0.43-1.36; high vs medium - OR: 1.03; 95% CI: 0.72-1.48; medium vs low - OR: 0.70; 95% CI: 0.42-1.19), house ownership (owned vs rented - OR: 1.28; 95% CI: 0.98-1.66), mother's schooling (OR: 0.89; 95% CI: 0.74-1.08), or father's schooling (OR: 1.01; 95% CI: 0.62-2.74).ConclusionsThe scientific evidence demonstrates that socioeconomic indicators are not associated with TDI in the primary dentition. The evidence of an association between a low income and TDI is weak. In general, studies had low risk of bias. Further prospective cohort studies are needed to confirm this association.

Elkhadem, A., S. Mickan, and D. Richards, "Adverse events of surgical extrusion in treatment for crown-root and cervical root fractures: a systematic review of case series/reports.", Dental traumatology : official publication of International Association for Dental Traumatology, vol. 30, issue 1, pp. 1-14, 2014 Feb. Abstract

BACKGROUND: Crown-root and cervical root fractures constitute a restorative challenge due to sub-gingival position of the fracture margin. Surgical tooth extrusion is one of the treatment options. There is uncertainty regarding the prognosis of such treatment modality.

OBJECTIVE: To assess adverse events of surgical tooth extrusion in the treatment for crown-root and cervical root fractures in permanent teeth.

METHODS: PubMed, Embase, and Google Scholar were searched through 15th of June 2012. Search was limited to English and Arabic languages. Reference list of relevant studies were hand-searched. Grey literature was searched using Open Grey. Two review authors independently extracted data, while only one assessed trial quality using 8-point methodological index for non-randomized studies (MINORS) scale. A sensitivity analysis was performed to exclude studies with suspected patients' duplicates.

RESULTS: Eleven case reports and eight case series involving 226 patients with 243 teeth were identified. No randomized controlled trials were found. The mean quality score for all case series was 9 suggesting a fair quality, while that of all case reports was 5 suggesting poor quality. Non-progressive root resorption is the most common finding following surgical extrusion with an event rate of 30% (95% CI 24.6-36.7%). This is followed by low event rates of tooth loss (5%), slight mobility (4.6%), marginal bone loss (3.7%), and progressive root resorption (3.3%). No ankylosis occurred to any extruded tooth, while severe tooth mobility showed negligible overall event rate of 0.4%.

CONCLUSION: The available evidence suggests that surgical tooth extrusion is a valid technique in management of crown-root and cervical root fracture of permanent teeth. Minimal adverse events and good prognosis are expected. Further, surgical extrusion can be considered as a treatment option in teeth suffering sub-gingival decay.

Elkhadem, A., and S. Wanees, "Fluoride releasing sealants may possess minimal cariostatic effect on adjacent surfaces.", Evidence-based dentistry, vol. 16, issue 1, pp. 12, 2015 Mar. Abstract

DESIGN: Randomised controlled trial.

INTERVENTION: Children with at least two sound permanent first molars and the presence of at least one sound distal surface of adjacent second primary molar were eligible. Children were randomised into three groups. In group one first permanent molars were sealed with a high-viscosity glass ionomer cement (GIC group; n = 926), group two received a resin-based fluoride containing sealant (RBF group; n = 923) and group three a resin-based sealant without fluoride (RB group; n = 927). Two examiners blind to group allocation conducted examinations at 30 months. Sealant retention and caries at D1-D3 levels was assessed. Bitewing radiographs were taken.

OUTCOME MEASURE: Caries prevalence and incidence rate ratios were calculated.

RESULTS: Two thousand seven hundred and seventy-six children were enrolled; the number of dropouts were similar in each group (GIC group; n = 75), (RBF group; n = 67), (RB group; n = 77). The prevalence of affected surfaces was significantly lower in the GIC (p = .03) and FRB groups (p = .04). Fewer new caries developed on the distal surfaces of the second primary molars in the GIC group than in the other two groups. Incidence rate ratios (IRRs) were: 0.70 (95% CI: 0.50, 0.68; p < .01) for GIC vs. RB; 0.89 (95% CI: 0.89, 1.28; p = .10) for GIC vs. FRB and 0.79 (95% CI: 0.53, 1.04; p = .005) for FRB vs RB. Partial sealant loss was higher in the GIC group (76 molars; 2.95%), compared with FRB (52 molars; 1.41%), RB group (50 molars;1.35%).

CONCLUSIONS: Fluoride-releasing sealants (high-viscosity GIC and fluoride RB) were demonstrated to provide protection against caries on the distal surface of second primary molars. This preventive strategy might contribute to maintaining the integrity of the mesial surfaces of the first permanent molars.

Elkhadem, A., and N. Orabi, "Weak evidence suggests higher risk for bracket bonding failure with self-etch primer compared to conventional acid etch over 12 months.", Evidence-based dentistry, vol. 14, issue 2, pp. 52-3, 2013. Abstract

DATA SOURCES: Medline, Embase, Cochrane Oral Health Group's Trials Register and the Cochrane Central Register of Controlled Trials (CENTRAL). Unpublished data were sought by searching, the National Research Register and Pro-Quest Dissertation Abstracts and Thesis database. There were no language restrictions.

STUDY SELECTION: Randomised and controlled clinical trials (including split mouth) directly comparing self-etch and acid-etch primers including patients with full-arch, fixed and bonded orthodontic appliances (not banded) with follow-up periods of at least 12 months were included.

DATA EXTRACTION AND SYNTHESIS: Two authors abstracted data independently, with disagreements being resolved by a third. The Cochrane Risk of Bias tool was used to assess study quality. A random effects meta-analysis was undertaken.

RESULTS: Eleven studies were included in the qualitative summary with five studies contributing to a meta-analysis. These five studies (n =3444 brackets, 1721 acid-etch, 1723 self-etch) had relatively low statistical and clinical heterogeneity. Meta-analysis demonstrated a tendency for a higher risk of failure (odds ratio 1.35; 95% CI, 0.99-1.83; P 5 0.06) with self-etch primers. The use of self-etch techniques was also associated with a small but statistically significant time saving (weighted mean difference 23.2 seconds per bracket; 95% CI, 20.7-25.8; P \0.001). There was insufficient evidence to assess the effect of bonding modality on demineralisation rates.

CONCLUSIONS: There is weak evidence indicating higher odds of failure with self-etch primer than acid-etch over 12 months in orthodontic patients, and there is strong evidence that a self-etch primer is likely to result in modest time savings (eight minutes for full bonding) compared with acid-etch.

Elkhadem, A., and P. Nagi, "No evidence for effectiveness of interventions used to treat displaced permanent anterior teeth.", Evidence-based dentistry, vol. 14, issue 3, pp. 83, 2013 Sep. Abstract

DATA SOURCES: The Cochrane Oral Health Group Trials register, Cochrane Central Register of Controlled trials (CENTRAL), Medline, Embase, LILACS and Dissertation, Theses and Abstracts databases.

STUDY SELECTION: Randomised controlled trials or quasi-randomised controlled trials that included a minimum follow-up period of 12 months.Data extraction and synthesisTwo review authors independently and in duplicate assessed the eligibility of all reports identified in the searches. Authors were contacted for additional information where required.

RESULTS: No randomised or quasi-randomised controlled trials were found.

CONCLUSIONS: We found no randomised or quasi-randomised trials of interventions to treat displaced luxated permanent front teeth. Current clinical guidelines are based on available information from case series studies and expert opinions. Randomised controlled trials in this area of dental trauma are required to robustly identify the benefits of different treatment strategies.

Elkhadem, A., and P. Nagi, "Effectiveness of MTA pulpotomy in primary molars: a critical assessment of relevant studies.", Evidence-based dentistry, vol. 14, issue 2, pp. 46, 2013. Abstract


STUDY SELECTION: Studies that evaluated the efficacy of MTA as a pulpotomy medicament in primary teeth were included, abstracts, observational studies and case reports were excluded. Only English language studies were considered.

DATA EXTRACTION AND SYNTHESIS: Studies were assessed and graded by two reviewers using a weighted criteria based system and a qualitative summary of the evidence provided.

RESULTS: Twenty-two studies were included, 17 studies compared MTA with formocresol, four studies compared MTA with calcium hydroxide, ferric sulphate, Portland cement, calcium-enriched mixture cement (CEM) and one study compared white MTA with grey MTA.

CONCLUSIONS: Based on the assessment criteria employed, there was no evidence that MTA was better than present materials and techniques as a pulpotomy medicament.

Fahnestock, S. R., "Evidence of the involvement of a 50S ribosomal protein in several active sites.", Biochemistry, vol. 14, issue 24, pp. 5321-7, 1975 Dec 2. Abstract

The functional role of the Bacillus stearothermophilus 50S ribosomal protein B-L3 (probably homologous to the Escherichia coli protein L2) was examined by chemical modification. The complex [B-L3-23S RNA] was photooxidized in the presence of rose bengal and the modified protein incorporated by reconstitution into 50S ribosomal subunits containing all other unmodified components. Particles containing photooxidized B-L3 are defective in several functional assays, including (1) poly(U)-directed poly(Phe) synthesis, (2) peptidyltransferase activity, (3) ability to associate with a [30S-poly(U)-Phe-tRNA] complex, and (4) binding of elongation factor G and GTP. The rates of loss of the partial functional activities during photooxidation of B-L3 indicate that at least two independent inactivating events are occurring, a faster one, involving oxidation of one or more histidine residues, affecting peptidyltransferase and subunit association activities and a slower one affecting EF-G binding. Therefore the protein B-L3 has one or more histidine residues which are essential for peptidyltransferase and subunit association, and another residue which is essential for EF-G-GTP binding. B-L3 may be the ribosomal peptidyltransferase protein, or a part of the active site, and may contribute functional groups to the other active sites as well.

Goss, D. J., L. J. Parkhurst, and H. Görisch, "Kinetic light scattering studies on the dissociation of hemoglobin from Lumbricus terrestris.", Biochemistry, vol. 14, issue 25, pp. 5461-4, 1975 Dec 16. Abstract

The kinetics of the pH-induced dissociation of the 3 X 10(6) mol wt hemoglobin from Lumbricus terrestris (the earthworm) have been studied in a light-scattering stopped-flow apparatus. The ligand dependent dissociation data were fit well by a simple sequential model. The data for CO and oxyhemoglobin are consistent with Hb12 leads to 2Hb6 leads to 12Hb. Methemoglobin at pH 7 appears to be hexameric and the dissociation is consistent with the model: Hb6 leads to 6Hb. In a sequential decay scheme for which light-scattering changes are monitored, the relative amounts of rapid and slow phase are determined by the rate constants as well as the molecular weights of intermediate species. Assignment of the hexameric intermediate is supported by an investigation of the sensitivity of the theoretical kinetic curves to the molecular weights of the intermediates. This assignment is further supported by the following: (1) the same model will fit the data for oxy- and CO-hemoglobin at all three temperatures (a 24-29-fold variation in rate constants), (2) evidence from electron microscopy shows hexameric forms, and (3) methemoglobin is apparently stable as a hexamer at pH 7. When CO replaces O2 as the ligand, the dissociation rate increases by a factor of four. The met is about 20 times faster than the initial oxyhemoglobin dissociation rate, but perhaps more relevant for comparing dissociation of the hexamer, the met rate was respectively 100 times and 500 times faster than that for the assumed hexameric forms of CO- and oxy-hemoglobin. The activation energies for the dodecamer to hexamer dissociation and for the dissociation of the hexamer to smaller forms were about 30 kcal/mol for oxy-, CO-, and methemoglobin.

Hendrickson, W. A., and K. B. Ward, "Atomic models for the polypeptide backbones of myohemerythrin and hemerythrin.", Biochemical and biophysical research communications, vol. 66, issue 4, pp. 1349-56, 1975 Oct 27. Abstract
Howell, R. M., and S. L. Deacon, "The interaction of clotting factor X with adsorbents containing bivalent cations.", Biochemical Society transactions, vol. 4, issue 4, pp. 718-20, 1976. Abstract
Jallon, J. M., Y. Risler, and M. Iwatsubo, "Beef liver L-Glutamate dehydrogenase mechanism: presteady state study of the catalytic reduction of 2.oxoglutarate by NADPH.", Biochemical and biophysical research communications, vol. 67, issue 4, pp. 1527-36, 1975 Dec 15. Abstract