Report on the investigation into the Tilapia population of Lake Naivasha, Kenya

Introduction: In 1959 fishing on a commercial scale was begun in Lake Naivasha, in the Kenya rift Valley, by Mr. F. Bisletti. The fish were taken fresh by lorry to the Nairobi market daily. Since nothing was known about the size and charateristics of the population and hence the potentia1 scope of the fishery Mr Bisletti requested advice from the Kenya Department of Game and Fisheries. Dr V.D. van Someren and Mr. P.J.P. Whitehead of the Fish Culture Research Station at Sagana visited the lake and invited the co-operation of E.A.F.F.R.O. to make a stock assessment using the methods which Mr. D.J. Garrod was applying to the Tilapia esculenta population of N. Lake Victoria. Van Someren and Whitehead also noted a few aberrant specimens which they thought might be hybrids. Accordingly D.J. Garrod and myself visited the lake several times in 1960 and 1961. It was hoped that this would provide a singularly good opportunity to study an almost virgin fishery based on a single population and to follow the changes in population size and structure as a known fishing pressures with gear of know selectivity, was applied. From this, it would have been possible to deduce ago composition, growth rate and recruitment, and hence compute the optimum yield ,which could be sustained. Mr Garrod submitted a report at the beginning of this work

The global retinoblastoma outcome study : a prospective, cluster-based analysis of 4064 patients from 149 countries

DATA SHARING : The study data will become available online once all analyses are complete.BACKGROUND : Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival. METHODS : We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models. FINDINGS : The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope). INTERPRETATION : This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.The Queen Elizabeth Diamond Jubilee Trust and the Wellcome Trust.https://www.thelancet.com/journals/langlo/homeam2023Paediatrics and Child Healt

Critical review of the methods used to measure the apparent dissociation constant and ligand purity in Ca2+ and Mg2+ buffer solutions

Using simulated Ca2+ and Mg2+ buffers, methods proposed to measure both ligand purity and the apparent dissociation constant (Kapp) were investigated regarding (1) predicted accuracy of both parameters and (2) generality of the solution. The Bers’ Ca2+ macroelectrode method [Bers, D. M., 1982 A simple method for the determination of free [Ca] in Ca-EGTA solutions Am. J. Physiol. 242, C404–C408] cannot be used with Mg2+-macroelectrodes and is partly arbitrary since the linear part of the Scatchard plot is judged subjectively. Iterative methods have therefore been introduced. Iteration based on the Bers’ method or the lumped interference in the Nicolsky–Eisenman equation also failed with Mg2+ macroelectrodes. The Oiki et al., method [Oiki, S., Yomamoto, T., Okada, Y., 1994. Apparent stability constants and purity of Ca-chelating agents evaluated using Ca-sensitive electrodes by the double-log optimization method Cell Calcium 15, 209–46.] cannot be applied to Mg2+ macroelectrodes. The pH titration method of Moisescu and Pusch (Pflügers, Arch., 355, R122, 1975) predicted EGTA purity and Ca2+ contamination, but Kapp values for EGTA were approximate. It cannot be applied to Mg2+ binding. The partition method [Godt, R.E., 1974. Calcium-activated tension of skinned muscle fibres of the frog. Dependence on magnesium adenosine triphosphate concentration J. Gen. Physiol. 63, 722–739.] only approximately estimated the Kapp. Calibration, maintaining contaminating [Ca2+]/[Mg2+] at <1 μmol l−1, and setting standards by dilution, is the ultimate check of calculated ionised concentrations, although technically difficult. The macroelectrode method of Lüthi et al. [1997. Calibration of Mg2+-selective macromolecules down to 1 μmol l−1 in intracellular and Ca+- containing extracellular solutions. Exp. Physiol. 82, 453–467] accurately predicted purity and Kapp at pKapp values >4 and was independent of electrode characteristics. It is considered the method of choice. Macroelectrode primary calibration should be carried out in solutions varying from 0.5 to 10 mmol l−1 combined with either Ca–EGTA or Mg–EDTA buffers; the [Ca2+] and [Mg2+] in other buffer ligands can be measured in a secondary calibration

Why are the problems associated with the lack of international standards for Ca²⁺/Mg²⁺ buffers still being ignored?

No abstract available

Why are the problems associated with the lack of international standards for Ca²⁺/Mg²⁺ buffers still being ignored?

No abstract available

Towards automatic segmentation and classification of mineralised bone

No abstract available

Comparison between measured and calculated ionised concentrations in Mg2+/ATP,Mg2+/EDTA and Ca2+/EGTA buffers;influence of changes in temperature, pH and pipetting errors on the ionised concentrations

The apparent dissociation constants (K app) and total ligand concentrations ([Ligand] T) from extensive published and unpublished macroelectrode measurements for Mg 2+/ATP, Mg 2+/EDTA and Ca 2+/EGTA buffers have been recalculated. These calculations were made feasible by the introduction of an Excel program which reduced the time of calculation for K app and [Ligand] T from over an hour to under five minutes. These estimations of K app and [Ligand] T allowed, not only a comparison between measured and calculated ionised magnesium and calcium concentrations ([Mg 2+] and [Ca 2+]) for Mg 2+/ATP, Mg 2+/EDTA and Ca 2+/EGTA buffers but also a comparison amongst calculated values. Calculated [X 2+] values always differed from measured, and calculated values differed amongst themselves by factors of at least 2. These variations cast doubts on the published absolute values for intracellular [Mg 2+] estimated by 31P-NMR and the resting values for [Ca 2+] in cells.The allowable range for [X 2+] in the buffers and consequently for K app and [Ligand] T has not been defined, which introduces uncertainties into published absolute values for [X 2+]. This paper shows that an upper limit of ± 10% deviation from the mean value for [X 2+] is attainable. This requires the temperature to be maintained within ± 0.5°C, pH within ± 0.01 units and pipetting errors of less than 0.25%. Until internationally defined buffer standards are available, the lack of correlation between measured and calculated [X 2+] means that measurement of K app and [Ligand] T and hence [X 2+] is more reliable than calculation