All-fiber optical frequency shifter

A new type of all-fiber frequency shifter is demonstrated. It is capable of operation at lower frequencies than traditional approaches based on surface acoustic waves and is believed to be unique in not requiring the removal of the fiber buffer coat. For 2.3-W electrical drive the prototype achieved a 2.5% conversion efficiency and greater than 20-dB unwanted sideband suppression.

Model of removal of immunoglobulins from plasma by extracorporeal immunoadsorption with sepharose-protein A

A mathematical model is developed which relates the time needed to perform immunoadsorption with Sepharose-Protein A to the column dimensions and choice of whether to use one or two columns. Measurements of parameters needed to apply the model, including the reaction rate constant and adsorption capacity, are reported. It is concluded that one large column can remove immunoglobulins more quickly than two smaller columns containing the same total volume of Sepharose-Protein A, but with the penalty of a greater loss of other plasma constituents. The model involves only simple computations, and can be applied to other immunoadsorbents if the dissociation constant of the complex formed by adsorption is lower than the final plasma concentration of the molecule adsorbed.

Comparative study of reaction kinetics in membrane and agarose bead affinity systems

Compared to conventional agarose bead affinity supports, a microporous nylon membrane exhibits greatly improved reaction kinetics as quantified in the reaction between gamma-globulin and immobilised protein A. The improvement is only observed when the solution of gamma-globulin is forced through the membrane pores. In the absence of flow in the pores, it is possible to relate approximately the rate of uptake onto either type of affinity support to independently determined diffusion coefficients. In the presence of flow, the reaction rate is similar for membranes having 0.45 and 3.0 microns diameter pores, and considerably smaller than predicted by the Smoluchowski formula.

Determination of diffusion coefficients of proteins in beaded agarose by gel filtration

A method for determining approximately the coefficient of diffusion of solute molecules in beaded gels, based on the analysis of breakthrough curves obtained in gel filtration, is described. This is applied to the diffusion of porcine serum proteins, gamma-globulin and fibrinogen in Sepharose CL-4B. The diffusion coefficients at 20 degrees C are 11.2 and 3.6 microns 2/s, respectively, about half those calculated from the partition coefficients using published equations.

From somatic variation to variant plants: mechanisms and applications

Plants from cell cultures show a high incidence of mutation. The causes of somaclonal variation are unknown, but the genetic consequences have been analysed. A range of genetic events are responsible, including single base changes; altered gene copy number; altered expression of multigene families; chromosome fragment interchanges; and mobilisation of transposable elements. Recent applications of these phenomena are discussed in this paper, for example, in vitro selection, somaclonal variation for agronomic traits, and limited gene transfer from cultured sexual and somatic hybrids. Research is outlined attempting to use high frequency chromosomal interchanges in wheat cell cultures to introgress genes from alien chromosomes. Two examples are cereal cyst nematode resistance on a rye chromosome and barley yellow dwarf resistance on a Thinopyrum chromosome. Some presumptive introgressed lines show selfed and backcross segregations, suggesting that the resistance, but not other alien markers, is now on a wheat chromosome.Key words: somaclonal variation, introgression, somatic hybridization, chromosome rearrangement, in vitro selection.

Somaclonal variation in wheat: genetic and cytogenetic characterisation of alcohol dehydrogenase 1 mutants

The progeny of 551 regenerants of the hexaploid wheat cultivar 'Millewa' were analysed for somaclonal mutants at the threeAdh-1 loci in hexaploid wheat. Seventeen regenerants gave rise to progeny having altered ADH1 zymograms. Progeny with altered zymograms in 13 of these regenerants were aneuploid. The remaining 4 regenerants gave rise to euploid progeny with altered ADH1 zymograms. The genetics of three of these somaclonal mutants is described in detail. These regenerants were interpreted to possess a 4Aα isochromosome, a 3BS/4Aα translocation and a 7BS/4Aα translocation, respectively.

The stability of preservative-free morphine in plastic syringes

The stability of preservative-free morphine in plastic syringes over 36 hours in the range of concentrations commonly used in our hospital to provide continuous morphine infusions was investigated. The morphine concentration remained at 100% (SD 1.5 percent) of the control values over 36 hours and demonstrates that the concentration of morphine is not reduced with time in these circumstances.

Centric fusion between nonhomologous rye chromosomes in wheat

The frequency of centric fusion has been compared in three wheat–rye double monosomic addition lines. In one plant, designated plant A, both monosomes were bibrachial. In the second plant, B, one monosome was bibrachial and one telocentric. In the remaining plant, C, both monosomes were telocentric. Rye centric fusion chromosomes were identified in the progeny by C-banding mitotic root-tip chromosomes and electrophoresis of endosperm storage protein. Four of 97 analyzed progeny of plant A and 4 of 96 analyzed progeny of plant B possessed centric fusion chromosomes. In contrast, none of the 492 progeny of plant C possessed centric fusion chromosomes. The data indicate that at least one bibrachial monosome is necessary for the efficient production of centric fusion chromosomes.Key words: centric fusion, centromeric misdivision, monosomes.

Fine needle aspiration cytology of an unusual presentation of leukemia. A case report

A 17-year-old active sportsman presented three weeks after a football injury with pain in the right hip and back. Osteomyelitis was the initial clinical diagnosis. A full blood count and erythrocyte sedimentation rate were normal. Fine needle aspiration of the anterior inferior iliac spine showed the presence of numerous blasts. This case represents an unusual presentation and method of diagnosis of acute leukemia.

Changing blood culture isolates in a referral neonatal intensive care unit

An analysis was made of all cases of bacteraemia that had occurred in the referral neonatal intensive care unit at Hammersmith Hospital during the years 1976--79. One hundred and thirteen infants had positive blood cultures; 27 were born in the hospital, and 86 admitted from elsewhere. This gave a rate of 5.7/1000 live hospital births, and 165/1000 outborn admissions to the unit. The latter infants were predominantly of very low birthweight or were ill. Thirty-three of the isolates were cultured in the first 48 hours of life (early) and the remaining 80 after that time (later). Staphylococcus epidermidis was the organism most often isolated both early and later. These results were different from those recorded in the previous 9 years (1967--75) from the same unit. Then, group B beta-haemolytic streptococcus was the organism most often isolated early, while Gram-negative bacteria predominated among later isolates. The changing nature of care may contribute to these findings.