Potassium substitution via the oral route: Does its efficacy depend on the anion of the potassium salt?

Summary In an open, randomized study, we investigated the effect of oral potassium chloride (KCl) and of potassium citrate/bicarbonate (K-cit/bic) in 42 patients with hypokalemia (3.5 mmol/l). In both groups 80 mmol K⁺ were administered daily. The parameters examined were serum potassium concentration, acid-base status, and urinary electrolyte excretion. Parameters were evaluated on days 0, 2, 4, and 6. With KCl, [K⁺] increased from 3.2± 0.2 (mean± SD) on day 0 to 3.8± 0.4 mmol/l on day 2 (p<0.005) and 4.0± 0.5 mmol/l on day 4 (p< 0.005). On day 6 [K⁺] was also 4.0±0.4 mmol/l (p< 0.005 vs day 0). With K-cit/bic, [K⁺] increased from 3.2± 0.2 to 3.7± 0.4 on day 2, 3.9± 0.5 on day 4, and 4.1± 0.6 mmol/l on day 6 (allp< 0.005 vs day 0). The increase of [K⁺] was not different between the two groups. Blood pH on day 0 was in the normal range in both groups and did not change significantly during the study. There was a decrease of carbon dioxide partial pressure (pCO₂) with KCl from 38.7± 4.9 on day 0 to 36.4± 3.6 on day 2 (p<0.05). On days 4 and 6, pCO₂ was back up to the basal level. In contrast, with K-cit/bic, pCO₂ rose from 35.0±5.8 mmHg on day 0 to 39.9± 5.8 mmHg on day 2 (p< 0.05). On days 4 and 6, pCO₂ was not different from day 0. The increase in urinary potassium excretion was equal in both groups. These results indicate that oral substitution with either KCl or K-citrate/bicarbonate may have only minor effects on the acid-base status under the conditions of the present study. Both potassium salts appeared to be equally effective in correcting hypokalemia via the oral route.Abbreviations GFR glomerular filtration rate - K-bic potassium bicarbonate - K-cit potassium citrate - KCl oral potassium chloride - pCO₂ carbon dioxide partial pressure - t.i.d. three times a day     

Acid-base balance and subjective feelings of fatigue during physical exercise

Six trained male subjects performed exercise on a bicycle ergometer. The external load was increased every minute by 10 watt until exhaustion. The subjects quantified their subjective feeling of fatigue by means of a rating scale.Parameters of acid-base balance (pH, ) were determined in arterial blood from the a. brachialis.Correction of the acidaemia by infusion of NaHCO₃ (8%) during exercise had no effect upon the subjective feeling of fatigue, and except for carbon dioxide output no effect upon some important physiological functions (heart rate, blood pressure, ventilation, and oxygen consumption) during submaximal and maximal exercise.     

Circulation to the brain of the rat during acute and prolonged respiratory changes in the acid-base balance

Summary The fraction of the cardiac output distributed to the brain was studied with a particle distribution method at different acutely induced arterialP _{CO 2} levels in control rats and in rats kept during 24 h before the experiment in an atmosphere containing either 10% CO₂ in air (prolonged hypercapnia) or 10% O₂ in N₂ (hypoxic hyperventilation producing prolonged hypocapnia). The curve relating the fraction of the cardiac output distributed to the brain and theP _{a CO 2} is shifted upwards and to the left after prolonged hypocapnia, and downwards and to the right after prolonged hypercapnia. A similar shift is observed when orthosympathetic vasoconstrictor activity is eliminated in the three groups of rats by alpha-adrenergic receptor blockade. The changes in the fraction of the cardiac output perfusing the brain are essentially due to modifications in the cerebral blood flow, since the cardiac output was not significantly influenced by the alterations in theP _{a CO 2}. The results are discussed in relation to the changes occurring in the CO₂/HCO ₃ ^– dissociation curve in blood and brain during prolonged respiratory changes in the acid-base balance.     

Effect ofP CO2, bicarbonate and lactate on the isometric contractions of isolated soleus muscle of the rat

Summary Isometric contractions of isolated soleus muscles of 3 weeks old rats show a potentiation of the maximal twitch tension when theP _CO2 is increased, or when the [HCO ₃ ^– ] is increased with a reciprocal decrease in [Cl^–]. The reverse response is observed on decrease of theP _CO2 and on decrease of the [HCO ₃ ^– ] with a reciprocal increase in [Cl^–].The addition of lactate ions results in a potentiation of the maximal twitch, whether accompanied by a reciprocal decrease in [HCO ₃ ^– ] or in [Cl^–].The maximal tetanic tension is augmented by rising theP _CO2, by increasing the [HCO ₃ ^– ] with simultaneous lowering of [Cl^–], or by the addition of lactate ions.     

Pufferung und Verteilung von Bicarbonat in Erythrocytensuspensionen mit verschiedenen Zellkonzentrationen

Summary Red blood cell suspensions in Ringer solution were used as a model for analysis of buffering and intracellular-extracellular exchange processes accompanying buffering in tissues. Bovine erythrocyte suspensions of varied cell concentration were equilibrated at various CO₂ tensions and the partition of bicarbonate between the intracellular and extracellular spaces was determined.It was found that with falling cell concentration a larger fraction of the bicarbonate formed or disintegrated by buffering was exchanged with the extracellular space, reaching a maximum of 83% at very low cell concentrations. Correspondingly, the apparent intracellular buffer value (=change of intracellular bicarbonate concentration per unit change of intracellular pH) was found to decrease with decreasing cell concentration to 17% of the true intracellular buffer value (=quantity of bicarbonate formed or disintegrated per unit red cell volume and per unit change of intracellular pH).It is concluded that by exclusive measurement of the pH and bicarbonate changes occurring in the intracellular space after changes of CO₂ tension the intracellular buffering power may be considerably underestimated.

     

An approach for the quality control in clinical microbiology laboratory by antibiotic susceptibility

It is important to develop a system for the prevention of various errors and the maintenance of the high quality level in the department of laboratory medicine. We developed a computer program to infer the species of microorganisms by assessing the minimal inhibitory concentration of respective microorganisms to various antibiotics, antibiotic susceptibility patterns(ASP). Retrospective analysis of 3,405 strains from 39 species using this program resulted in a sensitivity of 91.4% and specificity of 98.9%. Furthermore, in 1,660 strains isolated from September 1999 to August 2000, the efficacy of this program was evaluated using both this program and conventional identifying method such as VITEK, api and ATB. The discrepancy between this inferring method and conventional method was noted in 179 strains, revealing errors in 12 strains. We conclude that this ASP inferring program is useful for preventing errors and the maintenance of high quality examination by combining with conventional methods in the laboratory.     

Calculation of antibody and antigen concentrations from ELISA data using a graphical method.

A graphical method for determining the concentration of either the antibody or the antigen from ELISA data is presented in the form of a GWBASIC program. In the program, ELISAEQ, optical densities (OD) obtained from a 96-well ELISA plate can be input either directly by interfacing a microplate reader to the computer or manually. The program uses standard sample data, and selects the semilogarithmic linear range. Over this range, a least-squares method is used to determine the concentrations of interest. In addition, a hyperbolic interpolation formula is derived over the entire range for estimating the antibody or antigen concentration of the unknown samples whose OD is beyond the linear range.     

Procedures and a computer program for the determination of fractional protein synthetic rates by numerical solution of an implicit equation

Fractional protein synthetic rates may be determined in vivo by infusion with a labelled amino acid and measurements of the specific radioactivities of the free and protein-bound amino acid. The calculation requires the solution of an implicit equation which is usually done by the laborious and inaccurate method of interpolation from a series of standard curves. In this report a BASIC computer program (PROSYN) is given which enables a quick and accurate solution by a numerical method. The basis of several solution methods is described; the PROSYN program is capable of using either of two (bracketting and the secant method) of these procedures.     

Serial observations of arterial and mixed-venous blood gases after step change in ventilation

Summary In 22 dogs, subjected to a step change in ventilation, serial changes in blood gas composition and lactate and pyruvate concentrations of arterial as well as mixed venous blood were studied. The change of was approximately 20 mm Hg both in hypo- and hyperventilation. During hypoventilation the difference in various forms of CO₂ between arterial and mixed venous blood showed first a downward shift and then gradually increased, whereas during hyperventilation they progressively increased and reached a constant level within 10–20 min. This difference was assumed to be mainly due to more efficient CO₂ elimination through lung ventilation in hyperventilation as compared with CO₂ accumulation from tissue metabolism in hypoventilation.In vivo buffer slopes for CO₂ during hypoventilation were about half those in vitro, whereas during hyperventilation both slopes were approximately the same. In vivo arterial buffer slope was higher during hypoventilation and lower during hyperventilation as compared to that of mixed venous blood in the respective state of ventilation.This word was supported in part by a research grant from the Ministry of Education of Japan (857025).     

Computer control of fast protein liquid chromatography (FPLC)

A program has been developed to allow the control, the storage of method files, file text, peak and graphical data generated by a Pharmacia FPLC. The program allows for the remote control of a LCC 500 and the storage of up to 9,999,999 different method files. The program can either be used to start the FPLC and store text and peaks or also store monitor data from two monitors including percentage pump B, graphically. System requirements are an IBM PC or fully compatible microcomputer, mouse, CGA or EGA card and GEM Desktop software.     

胚胎连续组织切片的计算机三维重建

目的制备动物胚胎的连续切片,并利用计算机的三维重建技术,获得可视的“虚拟胚胎”。方法通过数码显微摄像系统对连续的石蜡切片进行拍照、拼接,获得胚胎连续切片的JPEG图像,再利用三维医学重建软件,把二维的切片图像重建成三维的“虚拟胚胎”。结果利用三维医学重建软件,重建得到“虚拟胚胎”,重建后的胚胎可进行任意的切割、旋转、操作回复等操作。结论医学三维图像工作室的三维重建软件运用于连续组织切片的计算机三维重建是完全可行的。     

Screening program theory: decision functions and protocols

A screening program is defined to include a set of tests, a decision function, and a protocol. The major characteristics of a screening program are the error rates of the individual tests, the overall error rates of the program, the costs of the individual tests, and the overall program costs. It is shown how to calculate the program error rates for any given decision function. The concept of a screening protocol is developed and a method for enumerating all protocols of a given decision function is given. A given protocol has two calculable costs: the average cost of testing a mutagen and the average cost of calculating a nonmutagen. A method for calculating these costs for any protocol is given. All decision functions utilizing up to five tests are enumerated.     

Computer control of a Braun Infusomat pump

Machine code programs have been produced to allow a simple method of communication between a computer and the Braun Infusomat pump. Commands are set up as character strings using a high-level language and passed to a machine code program which transmits them to the pump. Messages from the pump are received under interrupt control for display by the high-level language. Any error in communication is stored in memory and the appropriate action taken by the main application program.     

Determination of the neutron and photon spectra of a clinical fast neutron beam

A simple technique to determine the neutron and photon spectra of a clinical fast neutron beam is described. This technique involves making narrow beam attenuation measurements with a pair of ionization chambers and an iterative fitting program to analyze the data. A method is also described for determining the first-guess neutron spectrum for input into the iterative program. The results of the analysis yield spectra suitable for use in dose calculation algorithms and dosimetry protocols. Presented here is the first-known published photon spectrum from a clinical machine.     

Computer control of a Braun Infusomat pump

Machine code programs have been produced to allow a simple method of communication between a computer and the Braun Infusomat pump.

Commands are set up as character strings using a high-level language and passed to a machine code program which transmits them to the pump. Messages from the pump are received under interrupt control for display by the high-level language. Any error in communication is stored in memory and the appropriate action taken by the main application program.     

眼底病灶的计算机图像识别及临床应用可靠性测试

设计眼底病灶识别的计算程序，并进行可靠性试验。采用“区域生长法”，在ＶｉｓｕａｌＣ＾＋＋环境下设计程序；应用该程序测量糖尿病棉邕状渗出灶面积（１５只眼），计算变异系数以判断稳定性。结果表明渗出灶面积测量的变异系数为３．２２％～９．４６％。应用此方法识别并定量病灶简便迅速、稳定性好。     

PC program for comparing tracking indices in several independent groups

A method for computing a measure of tracking based on Cohen's kappa statistic for one-sample longitudinal data sets was previously described and implemented. This paper shows how one may test the equality of several kappas, each computed from an independent longitudinal sample. Thus, it is possible to formally compare groups of individuals with regard to stability in growth (or adaptive) patterns. Relative assessments of predictability in growth outcomes in different populations can be made with this approach. Also, when a common value of kappa is not contradicted by the data, a method to estimate this value and obtain a confidence interval for it is shown. A menu-driven GAUSS program for carrying out the procedure is described and made available. The method and program are illustrated with three samples of Guatemalan children. © 1992 Wiley-Liss, Inc.     

A microcomputer program for probit analysis of interleukin-2 (IL-2) titration data

IL-2 activity is commonly estimated in cell culture supernatants by an IL-2-dependent cell proliferation assay. This method is both reproducible and sensitive. However, it often appears from the literature that statistical analysis of the titration data either is disregarded or, when performed, is based on statistically incorrect assumptions. The proposed method is based on the principle of biological assay by parallel lines as applied to probit analysis of quantitative responses. The procedure has been embodied in a simple and interactive computer program which automatically estimates the IL-2 concentration in the biological sample, in terms of U/ml, and provides its standard error and confidence limits. This program is also suitable for quantitative determination of other biologically active substances that show a sigmoid dose/response relationship.     

A FORTRAN technique for correlating a circular environmental variable with a linear physiological variable in the sugar maple

This paper deals with a computer program adapted to a statistical method for analyzing an unlimited quantity of binary recorded data of an independent circular variable (e.g. wind direction), and a linear variable (e.g. maple sap flow volume). Circular variables cannot be statistically analyzed with linear methods, unless they have been transformed. The program calculates a critical quantity, the acrophase angle (PHI, phi o). The technique is adapted from original mathematics [1] and is written in Fortran 77 for easier conversion between computer networks. Correlation analysis can be performed following the program or regression which, because of the circular nature of the independent variable, becomes periodic regression. The technique was tested on a file of approximately 4050 data pairs.     

Quantifying bluetongue virus in adult Culicoides biting midges (Diptera: Ceratopogonidae)

A TissueLyser system (QIAGEN) was used to rapidly and accurately estimate bluetongue virus "loads" in individual adult Culicoides sonorensis Wirth & Jones (Diptera: Ceratopogonidae). The optimized homogenization program that was developed, involved shaking insects for 1 min at 25 Hz with 2- or 3-mm stainless steel ball bearings. This program was used to measure the quantities of bluetongue virus present in insects that had either been inoculated or had ingested a viremic bloodmeal through an artificial membrane. The virus titers obtained using either infection technique and the optimized program did not differ significantly from those obtained using a polypropylene motor-driven pestle, a method that is currently in common use for studies of vector competence). The advantages of the new method, as a rapid means of detecting fully disseminated infections in individual field-caught flies, are discussed. Its use is compared with the processing of pools of Culicoides by conventional methods, where the extent of dissemination of the virus is unknown and could wrongly implicate species that are of low importance in transmission.