bluuebunny/crossref_metadata_2025 huggingface dataset:
Reinforced poly(L‐lactic acid) fibres as suture material
Authors: Lam K. H. , Nijenhuis A. J. , Bartels H. , Postema A. R. , Jonkman M. F. , Pennings A. J. , Nieuwenhuis P.
Published: May 2005

In this study, reinforced poly(L‐lactic acid) (PLLA) fibers made by a dry‐spinning/hot‐drawing process were evaluated for use as a suture. The initial tensile strength of the PLLA fibers was lower than the initial tensile strength of the commercially available sutures: PDS, VicrylTM, silk, and Ethilon™. However, after 12 weeks immersion in a phosphate saline buffer at 37°C, PDS sutures have lower tensile strength than PLLA sutures and the tensile strength of Vicryl™ was unmeasurable because of fragmentation. Initially, PLLA fibers distinegrated into fibrils during degradation triggering an inflammatory response comparable to degradable multifilament sutures. However, the intensity of the inflammatory response against the PLLA fibers decreased and after 80 weeks implantation in the muscle layer of the abdominal wall of rats it was comparable to the one against Ethilon™. The inflammatory response against Ethilon™, which is considered to be nondegradable, increased in the same period, probably due to the change in shape. In practice, the handling characteristics of PLLA sutures are superior to the monofilament sutures like PDS and EthilonTM and comparable with the multifilament sutures like VicrylTM and silk. The knot security, but this remains to be investigated. It is concluded that dry‐spun/hot‐drawn (reinforced) PLLA fibers have the potential for use as long‐term degradable suture material. © 1995 John Wiley & Sons, Inc.
Effect of corrosion products (neodymium iron boron) on oral fibroblast proliferation
Authors: Evans R. D. , McDonald F.
Published: May 2005

The biological effects of the corrosion products of neodymium iron boron (Nd2Fe14B) magnets are largely unknown. The aim of this study was to identify the types of corrosion product and to evaluate the effect of the corrosion products (CP) of Nd2Fe14B magnets on the proliferation of human oral mucosal fibroblasts. Uncoated Nd2Fe14B magnets were stored in saline at 37°C for 6 months and the corrosion products collected. 100 μL of a cell suspension (human oral mucosal fibroblasts [4 × 104 cell/mL]) was aliquoted into 72 wells of a 96‐well plate, the remaining plates receiving culture medium only. After 12 h incubation at 37°C, each well then received 100 μL of either (A) culture medium, (B) 100% CP, (C) 50%, or (D) 0% CP. The plates were reincubated at 37°C for a further 48, 96 or 144 h. Fibroblast proliferation was assessed using the methylene blue uptake/elution technique. The compounds in the corrosion product were examined using quantitative X‐ray analysis. Statistical analysis (ANOVA, Bonferroni's test 0.05, SAS v 6.04), showed that at each time point, the cell numbers in groups B, C. and D were significantly lower than group A. Within groups B, C, and D no significant differences were found, despite the suggestion of a dose response effect. Fibroblast proliferation in the presence of corrosion products was significantly lower than with culture medium. Fibroblast proliferation did occur in the presence of 0, 50, and 100% CP. The actual corrosion products appeared to be salts of iron but 3.2% (±0.6) of neodymium chloride (NDCl3) was found. © 1995 John Wiley & Sons, Inc.
Comparison of diametral shrinkage of centrifuged and uncentrifuge simplex P® bone cement
Authors: Davies Jeffrey P. , Harris William H.
Published: May 2005

Reducing the porosity of bone cement substantially strengthens the cement in fatigue. However, concern has been raised that reducing the porosity of the cement would increase the shrinkage of the cement and thus compromise the cement‐bone interface. We measured diametral shrinkage of cement mantles prepared with and without centrifugation of the cement. Four cement preparations (centrifuged and uncentrifuged mixed with monomer at either room temperature or 0°C) were used to form cement mantles of four different thicknesses (2, 4, 6, and 8 mm) around a stainless steel rod. We conclude that porosity reduction dramatically increases the fatigue strength of bone cement without substantially changing the diametral dimensions of the polymerized cement when studied in the shape and volume of a cement mantle that would be used for total hip replacement. © 1995 John Wiley & Sons, Inc.
Production of L‐tryptophan in submerged culture
Authors: Malin Bernard , Westhead Jack
Published: May 2005

A strain of C. purpurea has been isolated which will produce L‐tryptophan from indole in submerged culture.

The L‐tryptophan produced is extracellular and in a free form.

Levels of up to 1·5 mg/ml of L‐tryptophan have been obtained.
An apparatus for the culture of algae under controlled conditions
Authors: Fogg G. E. , Smith W. E. E. , Miller J. D. A.
Published: May 2005

An apparatus is described in which large numbers of algal cultures can be maintained under the following conditions: (1) Constant temperature within the range 5 to 70°C, four different temperatures being maintained simultaneously; (2) uniform illumination at intensities up to 20,000 metre‐candles; (3) continuous shaking at variable speed; and (4) aeration under aseptic conditions with mixtures of up to four different gases in any desired proportions.

Among other features, thermoregulator heads, flow‐meters and heaters for sterile filters, of improved design are described.

To illustrate the use of the apparatus, data showing the effects of light intensity and temperature on the growth of Monodus subterraneus are presented.
Microbiological evaluation of peptones
Authors: Kheshgi Saeed , Saunders Richard
Published: May 2005

Information on a reliable method for determining the nutritive value of existing and experimental peptones is lacking in the literature. To overcome this handicap, a method for comparative evaluation of microbiological peptones has been developed.

The method is based on measuring the growth of eight carefully selected, fastidious, test cultures. The cultures are grown in presence and absence of yeast extract in an inorganic basal medium containing test peptone and a low and high level of glucose.

Statistical analysis of replicate peptone evaluations of six peptones, conducted over a period of six months, shows that 95 per cent confidence limits for this method are ± 2·5 to 7·9 per cent of the mean.

Four criteria are employed for determining the overall performance of 12 widely used, commercial peptones.

The method is very sensitive for detecting differences between batches of commercial peptones. With the aid of this method a new peptone ‘N‐Z‐Amine YT’ has been developed. Considering performance and relative cost, this peptone is the most economical of the peptones evaluated.
Batch centrifuge scale‐up for virus processing
Authors: Patrick William C. , Freeman Robert R.
Published: May 2005

The mathematical relationship between the throughput of a batch centrifuge and its mechanical characteristics has been applied to the scale‐up of one of the steps in virus processing for possible application to the production of vaccines and similar antigens. Slurries that contained a test virus were purified in a laboratory centrifuge. The Q/Σ relationship, developed by Ambler, was used to predict the operating conditions of a larger centrifuge in order to achieve the same clarification of slurry as that produced in the laboratory centrifuge. A correlation between conditions of centrifugation and amount of virus removed from the feed to the centrifuge shows that there is a well‐defined Q/Σ value at which significant concentrations of the test virus are sedimented.
The evaluation of a process for the preparation of co‐enzyme A from yeast
Authors: Reece M. C. , Donald M. B. , Crook E. M.
Published: May 2005

A process is described for the extraction of co‐enzyme A from dried yeast. It involves cold water extraction, charcoal adsorption followed by pyridine elution, preparation of an acetone power, co‐precipitation as the double cuprous complex with glutathione and removal of the glutathione by means of an ion exchange resin.

Improvements over previous processes include use of drum dried yeast plus cold extraction resulting in easy filtration and increase of throughput by a factor of three to five, together with the elimination of the ion exchange step formerly thought necessary to remove zine before the co‐precipitation stage. Under the best conditions yields represent 30% recovery of the co‐enzyme A in the yeast, the product being 90% pure.
An automatic apparatus for extraction of cell suspensions by repeated freezing and thawing
Authors: Billaudelle H. , Brunér P.‐O.
Published: May 2005

An account is given of the construction and operation of a fully automatic apparatus in which the material is kept under agitation in a closed container alternately surrounded by hot and cold alcohol supplied from separate baths. The apparatus has the following applications in microbiology and cell physiology:

Extraction of micro‐organisms and cell tissues by repeated freezing (F) and thawing (T) at variable temperatures and lengths of FT cycle. Extraction can be controlled automatically or manually. As a practical example of the use of the apparatus a description is given of the extraction of living virulent S. typhi bacteria.

Studies of the reactions of living micro‐organisms and tissues under varying physical conditions (e.g. high‐ and low‐temperature resistance experiments, osmotic studies, thermal synchronization of bacterial cultures, etc.).

If required, the normal gas mixture in the residual air space can without difficulty be replaced by other gases or mixtures such as CO2 or N2.
A highly sensitive katharometer and its application to the measurement of ethylene and other gases of biological importance
Authors: Burg Stanley P. , Stolwijk J. A. J.
Published: May 2005

The design and construction of a highly sensitive katharometer is described with special reference to the application of the instrument for the precise determination of traces of ethylene by gas chromatography. Factors influencing katharometer sensitivity, and the relative advantages and disadvantages of katharometers as compared with other types of detectors, are discussed.
Automatic feed device for laboratory‐size glass circulating evaporator
Authors: Barry Guy T. , Pierce Frank
Published: May 2005

A simple, rugged and compact automatic feed control attachment for the laboratory‐size glass circulating evaporator has been designed and constructed. Experience has demonstrated that this apparatus operates satisfactorily with a variety of aqueous biological extracts and solutions having resistivity values of 50,000 ohm‐in. or less. The device in adaptable to other evaporators and stills.
A method of achieving photosynthesis in a stainless steel fermentor
Authors: Hedén C.‐G. , Levin K.
Published: May 2005

A description of the cultivation of Rhodospirillum rubrum in 1,000 and 3,000 l. fermentors fitted with a special illumination device, and a discussion of the results.
Aeration‐agitation studies on the novobiocin fermentation
Authors: Maxon W. D.
Published: May 2005

Novobiocin fermentations in 20 l. baffled fermentors were studied as a function of the size and speed of the dual four‐bladed flat‐blade turbines used. Power input and sulphite oxidation rate measurements were made. The courses of pH, sugar utilization, mycelial dry weight, carbon dioxide evolution and antibiotic titer were determined. Optimum antibiotic yields were achieved at a power input of 0·5 h.p./100 gal, equivalent to a sulphite oxidation rate of 110 mmoles O2/l.h, when the impeller diameters were 29 per cent or 39 per cent of the tank diameter. A power input of 0·75 h.p./100 gal, equivalent to a sulphite oxidation rate of 160 mmoles O2/l.h, was required for equivalent results with the impeller diameter 49 per cent of the tank diameter. Some explanations of the lack of equivalent results with the large impeller are discussed.
Continuous antibiotic fermentation—design of a 20 litre, single‐stage pilot plant and trials with two contrasting processes
Authors: Bartlett M. C. , Gerhardt Philipp
Published: May 2005

The feasibility of producing antibiotics by single‐stage continuous fermentation was explored by means of a specially designed pilot plant. Both the chloramphenicol and penicillin processes appeared adaptable to such an operation. At dilution rates of 1·0 and 0·5 volume changes per day respectively, yields of from ¼ to ½ of the maxima obtained in batch operation were maintained in the steady‐state for more than 2 weeks.
Fermentation process kinetics
Authors: Gaden Elmer L.
Published: May 2005

Information on fermentation process kinetics is potentially valuable for the improvement of batch process performance; it is essential for continuous process design. An empirical examination of rate patterns in various fermentations discloses three basic types: (1) ‘growth associated’ products arising directly from the energy metabolism of carbohydrates supplied, (2) indirect products of carbohydrate metabolism and (3) products apparently unrelated to carbohydrate oxidation. Effects of operating variables on the primary kinetic processes, growth, sugar utilization and antibiotic formation, in the penicillin process, illustrate the special nature of this type.
Production and isolation of the antibiotic, oligomycin
Authors: Visser J. , Weinauer D. E. , Davis R. C. , Peterson W. H. , Nazarewicz W. , Ordway H.
Published: May 2005

Production of oligomycin has been studied in fermentations ranging from 100 ml in shaken flasks to 1000 gal in agitated and aerated tanks. The yields ranged from nothing to 3675 μ;g per ml. The main factor favouring the production of oligomycin was a medium giving good growth and supplying an abundance of slowly utilized energy. Media meeting these requirements contained yeast extract and/or molasses for growth and lard oil for energy. Glycerol, glucose or starch as the main source of carbon gave poor results. A pH close to 7 favoured oligomycin production. Considerable organic nitrogen was synthesized and excreted by the mycelium during oligomycin production.

Under suitable conditions practically all of the oligomycin remained in the mycelium. Extraction of the mycelium with acetone, concentration of the extract, removal of oily material with a low‐boiling hydrocarbon, decolourization and final crystallization from methanol or ethanol were the main steps in the recovery process. From pilot plant and tank fermentations about 4500 g of crystalline oligomycin have been prepared.

Three oligomycins, A, B and C were found by paper chromatography in even well‐crystallized oligomycin. In different lots the proportions varied from 10–75 per cent A, 4–90 per cent B and 0–36 per cent C. High yields and high percentages of A and C were obtained on the neutral, lard‐oil medium. Low yields and high proportions of B were given by the glycerol, low‐pH medium.
The disintegration of micro‐organisms by shaking with glass beads
Authors: Rodgers A. , Hughes D. E.
Published: May 2005

A new vibrator, commercially available as the Sonomec Wave‐Pulse Generator, is described, in which micro‐organisms may be disrupted by shaking with glass beads. The amplitude and frequency of vibration of the shaker may be varied independently by suitable linkages incorporated in the mechanism. A study has been made of the effect of several variables, particularly the height of the liquid column in the vibrating container, on the rate of disruption. A relation is shown to exist between the acoustic heating produced in the container by the passage of sound waves through the liquid and the rate of disruption of baker's yeast. It is considered that at most depths of the liquid column, the action is similar to that of other shakers, but at a certain depth of liquid, additional forces arise which greatly increase the rapidity of disruption. How these forces act is not known. Factors affecting the rate of disruption of baker's yeast, Corynebacterium xerosis and Bacillus megatherium have been studied and a comparison has been made of the fractions obtained by differential centrifugation of the cell dispersion and compared with similar preparations from the Hughes press.
Continuous centrifugation in virus processing
Authors: Patrick William C. , Freeman Robert R.
Published: May 2005

Ambler's Q/Σ relationship between the throughput of a centrifuge and its mechanical characteristics has been translated from batch data in order to predict operating conditions for continuous centrifugation in virus processing. A Sharples Laboratory Supercentrifuge was converted from batch to continuous operation and a slurry feed device was developed. A correlation between operating conditions for continuous centrifugation and amount of test virus recovered from the feed showed that the Q/Σ values at which high concentrations of the virus were recovered were almost identical to the Q/Σ values for significant virus recovery in batch centrifugation. Titration and gravimetric determinations of the sediments recovered from continuous centrifugation operations indicate that product purity might be influenced by operating conditions.
Effect of antifoam agents on oxygen transfer in deep tank fermentations
Authors: Phillips K. L. , Spencer J. F. T. , Sallans H. R. , Roxburgh J. M.
Published: May 2005

Development of a foam breaker which operates on the principle of rapid acceleration of foam through a nozzle has allowed large‐scale aerobic fermentations to be run without addition of antifoam agents. Fermentations have been investigated over a wide range of aeration levels in which oxygen supplied to the organisms was the limiting growth factor.

With Torulopsis utilis grown in a 5 per cent molasses medium. oxygen utilization followed an exponential pattern during the early phase of growth, with carbon dioxide production equal to the consumption of oxygen. At the point where oxygen supply to the organism became limiting, anaerobic fermentation began, and the consumption of oxygen remained constant. The level of oxygen absorption beyond which the respiratory quotient exceeded unity was used as a measure of limiting oxygen supply.

Addition of three types of antifoam compounds to T. utilis fermentations resulted in a marked depression of oxygen consumption, and a decrease in cell production. Incremental addition of small quantities of antifoam to maintain a constant foam level in the fermentor depressed the oxygen absorption rate to a lesser extent. Sulphite oxidation rates did not reflect the true value of oxygen absorption rates found for fermentations without addition of antifoam.
Theoretical aspects of sterilization of tissue culture medium by depth filtration
Authors: Daniels William F. , Hale Malcolm B.
Published: May 2005

Filtration theory is briefly reviewed with regard to possible application to sterilization by filtration. Of the different devices tested, Seitz asbestos sheets, acid‐treated to remove toxic materials, offered most advantages for routine use and scale‐up potential. The standard law of Hermans and Bredée best expressed mathematically, the filtration of tissue culture media sterilized by Seitz No. 6 laboratory filters. Data are presented showing the correlation between the performance of the Seitz No. 6 filter, and the Seitz No. 200 plate and frame press (involving a scale‐up ratio of up to 400 to 1). An expression:

derived from experimental data obtained, expressing time in terms of pressure, surface area, and volume of filtrate, enabled prediction of filtration parameters with accuracy acceptable for engineering purposes for unclarified media, and greatly improved for media which had been initially clarified.

The influence of streaming potential is discussed with regard to its influence on the course of a filtration.
Handling of antifoam oils for fermentations
Authors: Bungay H. R. , Simons C. F. , Hosler P.
Published: May 2005

Control of foams by oil additions is of large economic importance to the fermentation industry. Excessive foaming causes loss of material and contamination, while excessive oil additions may decrease the product formation. Antifoam oils may be synthetic, such as silicones or polyglycols, or natural, such as lard oil or soybean oil. Either will substantially change the physical structure of foam, principally by reducing surface elasticity.

Industrial antifoam systems usually operate automatically from level‐sensing devices. Methods for metering of oil under aseptic conditions are: timed delivery through a solenoid, two solenoids with an expansion chamber between, a motor‐driven hypodermic syringe, and certain industrial pumps.

Distribution devices can improve efficiency over straight‐pipe entry. Types described are spray distribution, diverter bars, and wick devices.
A conductance bridge method for the amperometric estimation of low oxygen tension
Authors: Gutmann F. , Moss F. , Lehoczky L.
Published: May 2005

Oxygen tension in aqueous media of the order of 10−6 to 10−9 molar is measured amperometrically by means of a stationary inert metal electrode. The electrolytic cell is connected into a high resistance bridge circuit, which is energized from a low resistance d.c. source of voltage adjusted to give a potential difference across the cell corresponding to a position on the diffusion current plateau of the first oxygen wave. This cell potential is monitored by means of a vacuum tube millivoltmeter and maintained constant. A vacuum tube millivoltmeter measures the bridge output. The bridge is initially balanced with the medium deoxygenated; subsequent introduction of low concentrations of oxygen dissolved in the medium unbalance the bridge. Either the resulting bridge output voltage, as read on the millivoltmeter, or the resistance change in the bridge arm opposite the cell, is related to the oxygen tension by means of a previous calibration. Both quantities are directly proportional to oxygen concentration, at least over limited ranges of such concentration changes. The method is also applicable to the estimation of other substances which can be discharged under amperometric conditions at a stationary electrode.
Polarographic measurement of oxygen supply and demand during aerobic propagation of a bacterial culture
Authors: Lemp John Frederick
Published: May 2005

The sampling method of polarographic analysis for dissolved oxygen in culture medium is unaffected by the presence of viable micro‐organisms. This method allows measurement of peak oxygen demand, critical oxygen concentration, and oxygen supply during actual mass propagation of an aerobic culture. Fermentation operating conditions may be adjusted to supply the oxygen required by the aerobic culture.
Developments in the production of mushroom mycelium in submerged liquid culture
Authors: Block S. S.
Published: May 2005

The process for the production of mushroom mycelium for food purposes has great potentiality. It would offer a simple, mechanized, inexpensive method for producing a nutritious food. Mushroom mycelium can be cultivated in submerged liquid culture on simple carbohydrate and nitrogen compounds with mineral salts. Yields are high and no special production problems are involved. Those species reported to have flavour are Agaricus campestris, Morchella crassipes, Lepiota rachodes, and Coprinus comatus. The mycelial growth is usually either in ball form or dispersed. The dispersed form, characterized by fine mycelium and secondary spores, may be a physiological mutation which gives greater yield but less flavour. Mycelium grown on solid media is said to have greater flavour than mycelium grown in submerged culture. Several methods for enhancing the flavour of the mycelium have been investigated. The taste of the mycelium has been variously reported from flavourless to equivalent or even preferable to that of the fruiting bodies. The fact remains, however, that it is only the problem of taste that has kept the process from commercial exploitation.
Process report: Large‐scale production of foot‐and‐mouth disease virus
Authors: Ubertini B. , Nardelli L. , Santero G. , Panina G.
Published: May 2005

A pilot plant is described for the mass cultivation of foot‐and‐mouth disease virus, in vitro, on calf kidney cell monolayers. The pilot plant produces up to 400 litres of virus per week; it can be enlarged with ease to a sufficient capacity to meet any requirements.
Clinical‐size dextran by direct fermentation (with NRRL B–1351 Streptococcus sp.)
Authors: Rogovin S. P. , Senti F. R. , Benedict R. G. , Tsuchiya H. M. , Watson P. R. , Tobin R. , Sohns V. E. , Slodki M. E.
Published: May 2005

Dextran, a polymer of glucose, has been widely used as a blood‐plasma volume expander. In whole culture fermentations most dextran‐producing organisms elaborate dextrans that have molecular weights of many millions and must be depolymerized and fractionated to obtain a product suitable for clinical use. An exception however is Streptococcus sp. (Strain DS–50) NRRL B–1351. In the work described here, this organism is used to produce clinical‐size dextran in high yields, both on a laboratory‐ and a pilot‐plant scale. With this process, fractionation is required but depolymerization is not. Fermentations of media containing 15 per cent sucrose are complete in less than 48 hours with 0·2 per cent inoculum. Yields of native dextran and clinical‐size dextran by methanol precipitation are 68 and 43 per cent of the theory, respectively. The structurally heterogeneous dextran formed by NRRL B–1351 has a higher viscosity for a given molecular weight than does NRRL B–512 dextran. The viscosity–molecular weight relationship for the former may be expressed by the equation [η] = 6·51 × 10−4Mw0·554. The high‐molecular weight fraction had approximately 75 per cent of 1,6‐like linkages, as compared with 87 per cent for the clinical fraction. All fractions had a lower ratio of 1,6 to non‐1,6 linkages than did NRRL B–512 dextrans.
Pilot plant studies on parboiling of rice—II. Dehydration
Authors: Mazumder A. C. , Bose A. N. , Ganguli N. C. , Guha B. C.
Published: May 2005

A compact dryer for the parboiling of paddy has been described. The use of steam tubes along the circumference of the shell has made high drying rates possible. The rate of water removal is dependent on steam pressure in the tubes. Blowing of pre‐heated air through the dryer shell is necessary. The optimum drying conditions for parboiled paddy as observed in the experimental rotary dryer are: (a) the steam pressure in the tubes should be about 45 lb/in2 gauge; (b) the feed rate should be 150 lb/h, approximately; (c) the rotation should be about 5 rev/min; (d) the inclination of the shell should be nearly 2° to the horizontal and (e) air at a rate of 100 ft3/min should be blown parallel to the feed, pre‐heated to a temperature of 90°C.
A rapid estimation of prednisolone produced by fermentative oxidation
Authors: Mizsei Antal , Szabó Antal
Published: May 2005

An analytical method has been devised for the rapid determination of prednisolone produced in a fermentative oxidation process. It allows frequent checking of concentrations of the prednisolone formed during the oxidation of hydrocortisone.

The estimation of prednisolone in the presence of hydrocortisone is based upon the diversity of colour shown by the chromogens produced from these steroids by sulphuric acid and ethanol. Using the optimal reagent mixture and conditions, the interference of hydrocortisone is negligible. The steroids are extracted from the fermentation broth with ethyl acetate. One test takes about 20 min.
An improved pH electrode assembly for pilot plant and plant fermentors
Authors: West J. M. , Stickle G. P. , Walter K. D. , Brown W. E.
Published: May 2005

A modified pH electrode assembly is desccribed which is capable of steam sterilization and which can be installed in steel fermentors of all sizes in a variety of ways. Its design is such that electrode life is prolonged and contamination hazards are reduced.
A preliminary study of depth filtration at a constant rate
Authors: Hale Malcolm B. , Daniels William F.
Published: May 2005

The constant‐rate operation of a system utilizing asbestos filter‐pads for the cold sterilization of a tissue culture medium is described. Filtration theory is briefly reviewed with regard to the constant‐rate process, and the results of several data treatment methods are reported. The standard law of Hermans and Bredée4, 5 best describes the constant‐rate data. Computation of the data, when plotted by the standard‐law method, results in two straight lines divided by a transition zone. The second region is characterized by a slower plugging rate and a plot of the standard‐law slopes versus the initial filtration pressures shows a linear relation. The constant‐rate method is compared with the constant‐pressure method and is found to yield equivalent overall filtrate rates at lower operating pressures.

The observed filtration behaviour is discussed, and available data are presented to indicate the sterilization capability of the filter.
Small‐scale studies of microbiological oxidation of hydrocarbons to long‐chain fatty acids
Authors: Lnday E. Margery , Donald M. B.
Published: May 2005

Several strains of Pseudomonas, Nocardia and incompletely identified soil isolates have been grown in a mineral salts plus hydrocarbon medium, and the fatty acids produced by the organisms have been isolated, identified and estimated. The results of an estimation of the percentage conversion to these acids under varying experimental conditions is discussed in relation to the metabolic systems involved. Some indication has been obtained that the hydrocarbon breakdown pathway by these organisms is that of ω oxidation followed by β oxidation. Preliminary experiments carried out with one strain of organism, Pseudomonas aeruginosa 5940, indicate that there may be some difference in the utilization of odd‐ and even‐chain hydrocarbons by this organism. An improvement of 3 ·8‐fold was obtained by using nitrate instead of ammonium nitrogen; 13‐fold by using continuous instead of batch operation; and 8‐fold by the use of liquid instead of solid paraffins, giving a total improvement of yield of 400‐fold.
Measurement of dissolved oxygen in fermentations
Authors: Phillips Donald H. , Johnson Marvin J.
Published: May 2005

Two methods have been investigated for the measurement of dissolved oxygen in fermentations: the tubing method and the probe method. The sensing elements for both methods are steam‐sterilizable and measure only the oxygen tension in the liquid phase. The tubing method is probably the most accurate and reliable method available for measurement of dissolved oxygen in fermentations but it requires extensive ancillary apparatus.
Aeration in fermentations
Authors: Phillips Donald H. , Johnson Marvin J.
Published: May 2005

Symptoms of oxygen deficiency and variations in dissolved‐oxygen level have been described in some typical aerobic fermentations. In bacterial fermentations, dissolved‐oxygen levels were almost the same in different parts of the fermentor. As a result, good correlations between apparent and true critical oxygen concentrations were obtained. Poor correlations were obtained in mould fermentations.
The chemical sterilization of liquid media with beta‐propiolactone and ethylene oxide
Authors: Toplin Irving , Gaden Elmer L.
Published: May 2005

The effectiveness of beta‐propiolactone (BPL) and ethylene oxides as sterilants for liquid microbiological media was studied. Preliminary tests against heavy suspensions of B. coagulans in various media confirmed the sterilizing levels found by earlier investigators. In actinomycin fermentation tests, both compounds were found to sterilize effectively at concentrations up to 0·5 per cent without significant effects on the growth‐promoting qualities of the medium. At the concentrations required to sterilize large numbers of spores (0·5–1·0 per cent), however, both agents exhibit inhibitory effects on the fermentation. In these cases BPL is less damaging than ethylene oxide.
Production of concentrated cell suspensions: The sponge fermentor
Authors: Freeman Robert R.
Published: May 2005

A novel fermentor is described in which aerobic microorganisms are grown on solid medium. Cellulose sponges support a nutrient‐agar medium, resulting in a large surface area for growth within a relatively small volume. The sponges are alternately squeezed and relaxed within a piston‐and‐cylinder‐type apparatus during fermentation. Provision is made for inoculation, harvesting, and for supplying air during operation. The apparatus has been operated semicontinuously in that there are enough cells left in the sponges after harvest to inoculate fresh medium. Cell concentrations of Serratia marcescens up to 84 × 1010 per ml have been recovered. A growth curve for this micro‐organism is given and sample data on semicontinuous operation are presented.
Chemical separation methods for common microbes
Authors: Nakamura Hiroshi
Published: May 2005

To collect microbes from suspensions by a process other than centrifugation, it has been found effective to add inorganic and organic electrolytes in the colloidal state. The addition of electrolytes causes a neutralization of charges on the particles in suspension resulting in their coagulation and precipitation. High‐molecular‐weight compounds which form micelles also promote coagulation and precipitation. It is believed that chemical collection is an extremely efficient method of treatment for the mass production of microbial suspensions.
Management of polyamine pools and the regulation of ornithine decarboxylase
Authors: Davis Rowland H.
Published: May 2005

The management of polyamine synthesis and polyamine pools differs fundamentally from that of most other small molecular‐weight endproducts. The polyamines are vital to growth and important cellular functions, but they are toxic in excess. I argue here that their multivalent cationic character, leading to binding to cell constituents, precludes fluent feedback inhibition of synthesis. This has led to the development of elaborate alternative regulatory mechanisms controlling ornithine decarboxylase, the key initial enzyme of the pathway. Poorly regulated polyamine synthesis and the toxicity of polyamines impose upon cells a need to control uptake and to dispose of excess polyamines. Recent data on polyamine transport suggest unorthodox mechanisms of accomplishing these functions.
Cell density‐dependent decrease in cytoskeletal actin and myosin in cultured osteoblastic cells: Correlation with cyclic AMP changes
Authors: Egan John J. , Gronowicz Gloria , Rodan Gideon A.
Published: May 2005

During bone development, osteoblasts form a contiguous layer along recently deposited osteoid and their morphology changes from fibroblast‐like to cuboidal. In culture, similar changes occur with increased cell density. We examined the possible role of cyclic AMP in this process since cyclic AMP was reported to increase in fibroblasts with increased cell density and similar shape changes were seen in response to parathyroid hormone, which also increases cellular cyclic AMP in osteoblastic cells. Osteoblast‐enriched rat calvaria cells were seeded at increasing density. The distribution between Triton X‐100 extractable and nonextractable actin and myosin was estimated by polyacrylamide gel electrophoresis. Intracellular cyclic AMP was estimated by prelabeling the cellular ATP pool with 3H‐adenine, followed by extraction and separation of 3H‐cAMP by high‐performance liquid chromatography. We found that osteoblastic cells contain about 40 pg actin and 5.3 pg myosin per cell. Around 60% of the actin and 70% of the myosin were in the nonextractable (crosslinked) form at cell densities of 10,000 to 50,000 cells per cm2. Above 50,000 cells/cm2, there was a cell density‐dependent reduction in crosslinked actin and myosin and a concomitant increase in cellular cyclic AMP. A comparable rise in cyclic AMP, produced by incubation with phosphodiesterase inhibitors, and treatment with other agents that increase cyclic AMP produced a similar decrease in the level of cytoskeletal actin and myosin. Cytochalasin B treatment, through its effect on actin polymerization, produced similar changes in cell shape and cytoskeletal actin. The findings suggest that an elevation in intracellular cyclic AMP may play a role in the density‐dependent changes in cell shape and microfilament organization observed in osteoblasts.
Effects of soluble factors and extracellular matrix components on vascular cell behavior in vitro and in vivo: Models of de‐endothelialization and repair
Authors: Madri Joseph A. , Marx Martin , Merwin June R. , Basson Craig , Prinz Christian , Bell Leonard
Published: May 2005

Vessel walls are comprised of several different cell populations residing in and on complex extracellular matrices. Each of the vascular cell types has diverse and sometimes unique functions and morphologies, and each has roles in repair processes following injury. Large vessel endothelial cells are known to respond to denudation injury by sheet migration and proliferation. This is in contrast to the migration through soft tissues with tube formation and subsequent lumen formation exhibited by microvascular endothelial cells in response to injury. Vascular smooth muscle cells of larger vessels respond to injury by migration from the arterial media into the intima, proliferation, and matrix biosynthesis, ultimately causing intimal thickening. Both these cell types exhibit “dysfunctional” phenotypes during their responses to injury. Microvascular cell responses to injury, while extremely variable, are less well documented. Specifically, responses to injury by microvascular endothelial vascular cells appear to be modulated, in part, by the composition and organization of the surrounding matrix as well as by the various soluble factors and cytokines found at sites of injury, suggesting that the extracellular matrix and soluble factors modulate each other's effects on local vascular cell populations following injury.
Lectin cell adhesion molecules (LEC‐CAMs): A new family of cell adhesion proteins involved with inflammation
Authors: Lasky Laurence A.
Published: May 2005

The means by which leukocytes, including lymphocytes, monocytes, and neutrophils, migrate from the circulation to sites of acute and chronic inflammation is an area of intense research interest. Although a number of soluble mediators of these important cellular interactions have been identified, a major site of great importance to the inflammatory response is the physical interface between the white cell and the endothelium. This critical association is mediated by an array of cell surface adhesion molecules. Previous data have demonstrated that the integrin subfamily of heterotypic adhesion molecules was a major component of these adhesive interactions, although it was clear that other, non‐integrin‐like molecules of unknown identity also seemed to be involved during the inflammatory process. A number of these other cell‐surface glycoproteins which may be involved with inflammation have recently been characterized by molecular cloning. These glycoproteins, including the peripheral lymph node homing receptor (pln HR), the endothelial cell adhesion molecule (ELAM), and PADGEM/gmp140, are all members of a family of proteins which are unified by the inclusion of three characteristic protein motifs: a lectin or carbohydrate recognition domain, an epidermal growth factor (egf) domain, and a variable number of short concensus repeats (scr) which are also found in members of the complement regulatory proteins. The appearance of lectin domains in all of these adhesion molecules is consistent with the possibility that these glycoproteins function by binding to carbohydrates which are expressed in a cell and/or region specific manner, and the members of this adhesion family have been given the generic name LEC‐CAM (lectin cell adhesion molecules). The discovery of adhesive proteins which appear to utilize the recognition of carbohydrate moieties for restricted cell adhesion may present new opportunities for the development of carbohydrate based anti‐inflammatory drugs.
Progesterone augments proliferation induced by epidermal growth factor in a feline mammary adenocarcinoma cell line
Authors: Modiano Jaime F. , Kokai Yasuo , Weiner David B. , Pykett Mark J. , Nowell Peter C. , Lyttle C. Richard
Published: May 2005

Steroid hormones and peptide growth factors promote growth and development of normal mammary tissues and some types of breast cancer. Ovarian steroids may influence mammary growth directly or indirectly. The epidermal growth factor (EGF) family of proteins may also regulate mammary growth. These two pathways may function independently of each other or they may act in concert, with steroids inducing transcription of genes that encode growth factors or growth factor receptors. We used a feline mammary adenocarcinoma cell line (K12) to address whether there was an interrelation between progesterone (PGN) and EGF‐associated growth pathways. K12 cells responded to EGF by a dose‐dependent increase in proliferation. PGN or promegestone (R5020, a synthetic progestagen) alone did not stimulate K12 growth, but when EGF and PGN, or EGF and R5020 were combined, they were synergistic. This synergistic response was abrogated by the PGN receptor antagonist RU486 or by antibodies that blocked binding of EGF to its receptor. K12 cells expressed characteristic double‐affinity EGF receptors, as well as p185 (a functionally and structurally related protein, product of the neu gene) on their surface. PGN receptors were also found on intact cells and in cleared cytosols. Stimulation of K12 cells by PGN or by R5020 induced a two‐ to threefold increase in the number of high‐affinity surface EGF receptors after 24 h. Stimulation of these cells by PGN also affected the relative levels of phosphorylation of the EGF receptors and p185 within minutes, but not of other cellular phosphoproteins. Our results show that PGN enhances the EGF‐induced growth of K12 cells and suggest that this effect may be mediated at least partly via an increase in the number or function of high‐affinity EGF receptors.
Epidermis generated in vitro: practical considerations and applications
Authors: Parenteau Nancy L. , Nolte Cynthia M. , Bilbo Patrick , Rosenberg Mireille , Wilkins Leon M. , Johnson Eric W. , Watson Stephen , Mason Valerie S. , Bell Eugene
Published: May 2005

The technology for culture of epidermis is one of the most advanced to date for generation of a tissue in vitro. Cultured epidermis is already used for a number of applications ranging from use as a permanent skin replacement to use as an organotypic culture model for toxicity testing and basic research. While simple epidermal sheets have been grafted successfully, more advanced models for skin replacement consisting of both dermal and epidermal components are in development and being tested in a number of laboratories. One of the most advanced in vitro models is the living skin equivalent, an organotypic model consisting of a collagen lattice contracted and nourished by dermal fibroblasts overlaid with a fully formed epidermis.
Expression and function of interleukin‐6 in epithelial cells
Authors: Krueger James , Ray Anuradha , Tamm Igor , Sehgal Pravinkumar B.
Published: May 2005

Epithelial cells both produce and are affected by interleukin‐6 (IL‐6). Experiments with an adenocarcinoma‐derived cell line (HeLa) reveal that activation of the transfected human IL‐6 promoter occurs largely through two partially overlapping second messenger (cAMP, phorbol ester)‐ and cytokine (IL‐1, TNF, serum)‐responsive enhancer elements (MRE I, −173 to −151 and MRE II, −158 to −145). MRE I contains the typical GACGTCA cAMP and phorbol ester‐responsive (CRE/TRE) motif, whereas MRE II defines a new CRE/TRE motif that contains an imperfect dyad repeat. The mechanism of dexamethasone‐mediated repression of IL‐6 gene expression in epithelial cells involves occlusion of the entire MRE enhancer region and of the core‐promoter elements (TATA‐box and RNA start site) by ligand‐activated glucocorticoid receptor. Enhanced levels of IL‐6 expression are observed in many solid tumors and in the hyperprolifer active (and glucocorticoid‐suppressible)lesions of psoriasis. In cell culture, IL‐6 enhances, inhibits, or has no effect on the proliferation of epithelial cells depending upon the cell‐type examined IL‐6 enhances proliferation of keratinocytes but inhibits that of breast carcinoma cell lines ZR‐75‐1 and T‐47D. In these breast carcinoma cells, IL‐6 elicits a major change in cell phenotype which is characterized by a fibroblastoid morphology, enhanced motility, increased cell‐cell separation, and decreased adherens type junctions (desmosomes and focal adhesions). The new data identify IL‐6 as a regulator of epithelial cell growth and of cell‐cell association.
Genetics of the malignant progression of astrocytoma
Authors: Mikkelsen Tom , Cairncross J. Gregory , Cavenee Webster K.
Published: May 2005

The tendency of human cancers to progress towards a more malignant state over time is a well described biological phenomenon. Recent investigations elucidating the genetic nature of malignancy and the possible mechanisms responsible for this evolution have suggested that a sequential pathway may exist whereby a cell population accumulates a nested set of genetic aberrations which endow it with the ability to overwhelm other populations and dominate the tumor. Human astrocytomas are a dramatic case in point, where specific genetic events of amplification and deletion are seemingly related to the stages of malignancy. The identification of these aberrations represents the first stage in the dissection of the temporal process of this cancer. Its augmentation with functional analyses will likely allow a fuller genetic description of in vivo transformation.
Regulation of the sarcoplasmic reticulum Ca2+‐release channel requires intact annexin VI
Authors: Hazarika P. , Sheldon A. , Kaetzel M. A. , Díaz‐Muñoz M. , Hamilton S. L. , Dedman J. R.
Published: May 2005

Annexin VI has eight highly conserved repeated domains; all other annexins have four. Díaz‐Muñoz et al. (J Biol Chem 265:15894, 1990) reported that annexin VI alters the gating properties of the ryanodine‐sensitive Ca2+‐release channel isolated from sarcoplasmic reticulum. To investigate the domain structure of rat annexin VI (67 kDa calcimedin) required for this channel regulation, various proteolytic digestions were performed. In each case, protease‐resistant core polypeptides were produced. Annexin VI was digested with V8 protease and two core polypeptides were purified by Ca2+‐dependent phospholipid binding followed by HPLC. The purified fragments were shown to be derived from the N‐ and C‐terminal halves of annexin VI, and demonstrated differential immunoreactivity with monoclonal antibodies to rat annexin VI. While both core polypeptides retained their ability to bind phospholipids in a Ca2+‐dependent manner, they did not regulate the sarcoplasmic reticulum Ca2+‐release channel as did intact annexin VI.
From growth arrest to growth suppression
Authors: Philipson Lennart , Sorrentino Vincenzo
Published: May 2005

Since the introduction of the cell cycle concept two approaches to study growth regulation of cells have been proposed. One claims that cells are naturally quiescent, requiring a stimulatory encounter with growth factors for induction of cell division. The other considers cellular multiplication as the natural steady‐state; cessation of multiplication is thus a restriction imposed on the system. In the latter case emphasis is mainly on the signals involved in arrest of multiplication. This Prospect focuses on specific events occurring in mammalian cells at growth arrest, senescence, and terminal differentiation, specifically emphasizing the growth inhibitory factors, tumor suppressor genes, and other signals for growth suppression.