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By L. Nahai

THE OUTPUT ff the mineral industry in 1964 in both non-Communist and Communist Europe showed an upward trend for most countries in keeping with the higher index of overall industrial production. Comparable indexes of mineral industry production for non-Communist and Communist Europe (including the U.S.S.R. in Asia) are not available, primarily because the U.S.S.R. does not report details of its industrial production by industrial sectors. However, available data both in the form of index numbers on production published by the United Nations and based on data as reported to the United Nations by the various countries, and actual production data for selected major commodities published by the various European countries reflect generally expanded output by both the extractive sector and the processing sector of the mineral industry in most of the 26 nations of Europe.

Jan 1, 1966

By M. J. Beus, B. Stewart, S. Iverson

Synopsis U.S. Mine Safety and Health Administration (MSHA) accidents statistics have identified ore-pass hazards as a significant safety problem in U.S. underground metal mines. The statistics show that nearly 75% of injuries are directly or indirectly related to pulling or freeing of ore-pass chutes, the use of hand tools in ore passes, fails of broken rock in ore passes and structural failures of chutes or gates and ore-pass walls. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating hazards in and around ore passes in hard rock mines. Risk assessment methods, such as fault-tree analysis, have been employed to identify the most probable causes of orepass failures, define research priorities and analyse the factors that result in malfunctioning and unsafe ore passes. Static and dynamic loads are being measured in a laboratory setting with the use of a reduced-scale orepass mock-up. Field tests are being initiated in mine ore passes to determine static and dynamic loads. Data from the test ore passes are being compared with data from the mine to characterize true system behaviour. Computer modelling with the use of closed-form solutions, finite-element analyses and a newly developed particle flow code predicts static and dynamic leads from the flow and the impact of ore and waste in the ore pass. Preliminary results indicate that dynamic impacts from ore and waste rock might be considerably greater than expected. The total static load is substantially less than is typically used fur the structural design of chute and gate support members. It is suggested that damping factors, normal and shear stiffness and mass frictional characteristics have a significant effect on particle flow and resulting impact loads. This is being verified with the use of results from laboratory tests, field tests and particle flow analyses. Ore passes are vertical or steeply inclined openings in a rock mass through which ore and waste are transported and where they mar also be stored. A typical underground mining system is shown in Fig. 1. The arrows indicate the locations of ore passes and loading pockets and their relative configurations. The control of material flow is potentially one of the most hazardous operations in underground mining. According to MSHA data. most of the ore pass-related accidents in the U.S.A. are associated with the loading-unloading cycle and removal of blockages from ore passes. In particular, attempts to free ore hang-ups have resulted in multiple fatalities. The hazards are obvious; there is uncertainty as to when the ore will break loose and miners are unable to escape falling rock to a safe location. Although ore passes and chutes and gate systems for underground metal and non-metal mines roust meet the requirements specified in the U.S. Code of Federal Regulations (CFR). Parts 57 and 75, recent structural failures of ore-pass linings and gates have underlined the lack of adequate ore-pass design standards available to both MSHA enforcement staff and mine engineers. Because of the importance of an ore pass to the safe operation of a mine design criteria need to be assessed and new guidelines developed. Researchers at the Spokane Research Laboratory of the Nationals Institute for Occupational Safety and Health (NIOSH) are investigating hazards in and around ore passes in hard rock mines and studying design criteria for ore passes. The near-term goal is to conduct laboratory and field experiments and computer modelling to evaluate the ore-pass design criteria currently used. Literature searches, field site

By C. F. McCarroll

The effectiveness of an industry's safety activities can be gaged best by the accident records of that industry. In an effort to gage conditions in the petroleum industry, and with the objective of helping to reduce the number of accidents in it, the Bureau of Mines from time to time has tabulated, analyzed, and published pertinent statistical information.3/. These reports have dealt with distribution, causes, and costs and related phases of accidents for various and collective divisions of the petroleum industry in several sections of the country. This type of study aids the personnel of the Bureau in planning the course of its activities in accident-prevention work and gives useful data to persons engaged or interested in the promotion of safety in the petroleum industry, which will aid them in their efforts to reduce the number and severity of accidents. A majority of petroleum operators and "service? contractors have acknowledged their responsibility to provide their employees with safe working conditions and to their stockholders for greater economic value of invested capital by establishing safety divisions within their respective organizations. Such divisions have a primary duty, namely, to see that properly designed and guarded machinery and working equipment are furnished the employees and that they are trained in the safest practical methods of performing their work. Some companies and individual operators, however, have shown little or

Jan 1, 1939

By G. L. Oldwright, Virgil Miller

"The data presented in this paper were collected at the smelter of the Consolidated Mining & Smelting Co. of Canada Limited, Trail (Tadanac), Brithish Columbia. The authors are greatly indicated to S.G. Blayrock, vice president and general manager; James Buchman, smelter superintendent; and the staff members mentioned in Report of Investigation 3243. The authors are exceedingly grateful to George Murray, assistant smelter superintendent, for his keen interest, suggestions, and help in carrying out this investigation.INTRODUCTIONThe methods of charign the blast furnaces at Toole and Kelloggs were noted in Report of Investigations 2957 and 3094 respectively. Report of Investigations 2957 cited (4 to 9 inclusive) Hofman's Metallurgy of Lead (p. 226) and the work of A.S. Dwight, Thompson and Sicka, the staff of the Engineering and Mining Journal, and L.D. Anderson, N.F. Collins, in The Metallurgy of Lead (Chas. Griffin, London, 1910) also gives (pp. 247 254) the principles that he believes govern the successful charging of the blast furnace."

Dec 1, 1934

By Gordon T. Austin

The combined production value of natural abrasives, which consist of tripoli, special silica stone, garnet, and emery, decreased in 1986. Shipments of processed tripoli increased slightly in quantity and 20% in value. Production of garnet, a common iron- aluminum-silicate mineral, decreased 12% in quantity and value. There was a 4% increase in the quantity and an 11% increase in the value of refined garnet shipped when compared with 1985 shipments, a new record high. Production of crude special silica stone decreased 7% in quantity and slightly in value, and shipments of finished special silica stone products decreased slightly in quantity and increased 229% in value. Production of emery, an impure aluminum oxide, increased 77% in quantity and increased 269% in value of product mined and shipped. [ ]

Jan 1, 1988

By O. C. Blade

Total sales of diesel fuel in the United States continue to Increase. This growth is due primarily to two causes: More conversion to diesel units by the rail-roads In recent years, and the greater use of diesel engines in trucks, busses, and tractors. Following are some figures on the distribution of the fuel computed from data issued by the Bureau of Mines.2/ [ ] Deliveries of diesel type fuel from refineries totaled 91,522,000 barrels during the first six months of 1955,3/ corresponding figure for 1954 was 91,170,000 barrels. Information on the properties of this engine fuel is very important to the petroleum industry, engine manufacturers, and consumers. To supply such information the American Petroleum Institute and the Bureau of Mines, United States Department of the Interior, under cooperative agreement, are conducting annual surveys of diesel fuel oil produced in refineries in this country.

Jan 1, 1955

The safety analysis of shaft-sinking operations included a review of accident reports from coal and metal-nonmetallic mine shaft-sinking projects in the United States, a review of foreign and domestic shaft laws, and discussions with shaft contractors and Federal mine inspectors. Accident data were studied to identify the most common and the most severe types of shaft accidents and to determine their immediate and contributing causes. Additional factors such as worker training and experience, equipment and sinking procedures, regulations and enforcement practices were also investigated to determine their impact on shaft safety. The results of the study are summarized in recommendations for improved training of shaft miners and clarification of Federal shaft-sinking regulations. A guide to assist mine inspectors in examining shaft-sinking projects is also included.

Jan 1, 1977

By V. E. Erwin, W. W. Adams, E. V. Walters

"Increased production of explosives in the United States in 1933 compared with 1932 is shown by statistics compiled by the Demographical Division, Health and Safety Branch, United States Bureau of Mines. The figures relate only to explosives used for industries purposes, such as mining, quarrying, and road building, and do not cover nonindustrial explosives, such as ammunition or fireworks. Industrial explosives include black blasting powder, permissible explosives, 5 and high explosives other than permissibles figures in the tables of this report were compiled from reports covering sales by the individual companies manufacture of explosives in the United States in 1933. Because of the close agreement among the several series of figures, the quantity of explosives sold is considered as reflecting production and consumption, and the three terms ""sales"", ""production"", and ""consumption"" are used interchangeably in the discussion unless otherwise stated.Of the principal industries that use high construction operations accounted for the largest percentage of increase in consumption during 1933; metal mining and quarrying also used more of this class of explosives than in the previous year. Coal mining is the chief consumer of permissible explosives; the figures for 1933 showed that bituminous-coal mining used a larger quantity than in 1932, and that anthracite mines also showed a small increase. Although a net increase of less than 1 percent in consumption was reported for black blasting powder, large increases in use of this class of explosives were reported for metal mining, miscellaneous types of work, and bituminous-coal mining. (See table 1.)"

Nov 1, 1934

By Clarke E. Schuetze

This project had as its objective the experimental investigation of water capsule production utilizing the Southwest Research Institute's submerged nozzle encapsulation apparatus (U.S. Patent 3,389,194). Initial efforts on this project involved nozzle configuration and shell formulation optimization. The shell formulation developed on a prior program was modified during the course of the project to obtain the best balance of capsule breakage resistance and water retention. Subsequent effort centered on determining operating conditions which would produce the best quality capsules for each candidate shell formulation as determined by laboratory tests. Some preliminary work was done to increase the production capacity of the encapsulation equipment. The program was extended with major emphasis concerned with scale-up studies of capsule production capacity and the treatment of problems associated with grouting cartridge fabrication. During the course of the program, water-containing capsules were produced which have good long-term water retention, block resistance and adequate strength. Using a single-nozzle design, a production capacity of 15.9kg (35 pounds) per hour was demonstrated to give acceptable capsules based on initial results.

Jan 1, 1978

By R. R. Falier, W. E. Rice

"PURPOSE OF REPORTThis paper presents the results of a series of tests made by the U. S. Bureau of Mines in cooperation with The Ohio State University Engineering Experiment Station as part of an investigation on the use of fuel in kilns.This report is preliminary and gives only enough of the test data to illustrate results and show the reasons for the successes and failures of the method of firing investigated; fuller details will be included in the final report.PERSONNEL FOR TESTSThe investigation is conducted under supervision of P. Nicholls, supervising fuel engineer, of the United States Bureau of Mines, and G. A. Bole, research professor, of The Ohio State University. These tests were made under direction of W. E. Rice, associate fuel engineer, assisted by R. R. Faller, assistant fuel engineer, of the United States Bureau of Mines; H. C. Harrison, senior research engineer (until October 1, 1930), C. R. Austin, senior research engineer (since October 1, 1930), and H. K. Van Sohoick, junior research engineer, of The Ohio State University. M. J. Rice, field engineer, represented the manufacturer of the stoker.PURPOSE OF INVESTIGATIONThe general aim of the investigation is to develop more economical methods of using fuel in kilns and to improve the over—all efficiency of the process of firing by methods that will produce ware of better quality. One phase of this investigation is the burning of coal on an automatic stoker to gain the advantages of control, constant rate of application of heat, and ability to burn cheaper coal than can be used in the hand—fired furnaces of kilns. It a stoker in to be used it is desirable that the coot of the installation should be low, the control of operation simple, and the distribution of heat in the kiln as good or better than with hand firing. These desiderata were sought in the stoker and furnaces that were used for the tests described herein. The tests were made to determine whether it is feasible to fire a large kiln with a single stoker, whether the use of a single furnace simplifies control, and whether the admission of all the hot gam at the center of the kiln will give symmetrical distribution of heat."

Aug 1, 1931

By John R. McWilliams

This report is one of a series published by the Bureau of Mines describing methods and practices at various mines throughout the United States. A previous program, conducted from 1928 to 1939, was well received by the mining industry and technical institutions and provided much source material for engineering textbooks and technical handbooks. The stringent wartime demands on the mining industry, the rapidly changing postwar economic situation, and greatly accelerated technologic growth have combined to render many of the previous data obsolete. The objective of the present program is to assemble reliable technical information on mining methods and practices throughout the country and present it for the use of the mining industry, technical schools, textbook authors, and other interested persons. This report deals with the design and development of the Berkeley open- pit mine at Butte, Mont., owned and operated by The Anaconda Company. The Berkeley pit is but one facet of a well-organized and integrated copper-mining operation involving the entire Butte district. Vein-type mining, important for 75 years, is still in progress at depths from 600 feet to nearly 1 mile; on intermediate levels, low-grade ore left untouched by earlier vein-type mines is being extracted by block caving entire ore zones,3/ and secondarily enriched but lower grade near-surface portions of the same ore zones are being mined by open-pit operations (fig. 1). The Berkeley pit itself is named for the Berkeley mine, one of the old mines that extracted copper ore from high-grade veins in the area that now will be mined by open-pit methods.

Jan 1, 1959

By Forrest T. Moyer

The overall injury experience, excluding officeworkers, at metal mines and mills during the period 1961-63, reported by operators, was 174 fatal and 11,357 nonfatal disabling work injuries during an aggregate worktime of 451 million man-hours. These injuries occurred at a frequency rate of 25.55 per million man-hours, comprising 0.39 for the fatal and 25.17 for the nonfatal injuries. The combined severity rate of the disabilities was 3,779 days lost or charged per million man- hours, consisting of 2,314 for the fatal and 1,465 for the nonfatal injuries. The average severity of all disabilities during 1961-63, was 148 days per injury. The number of days lost and/or charged, ex- cluding officeworkers, at metal mines and mills during the period 1961-63, was 1,440,000 days charged to fatal injuries and 661,290 days lost from nonfatal injuries. An average of 70,966 men were at work daily. The outstanding cause for fatal injuries was the fall of rock or ore from the back, while most of the nonfatal injuries were caused by handling materials, slips or falls of persons, machinery, falls of rock or ore from back and side, and haulage. Injury experience at primary nonferrous smelters, refineries, and reduction plants during 1961-63, excluding officeworkers, was 23 fatal and 3,214 nonfatal disabling injuries during a total work- time of 277 million man-hours. The injuries occurred at frequency rates of 0.08 per million man-hours for the fatalities and 11.61 for the nonfatal disabilities. The severity rate for all injuries of 1,085 days lost or charged per million man-hours comprised 498 for fatal and 587 for nonfatal injuries. The number of days lost, excluding officeworkers, at primary nonferrous smelters, refineries, and reduction plants during 1961-63 was 138,000 from fatal injuries and 162,385 from nonfatal injuries, An average of 34,938 men were at work daily an active plant days during the three year period. The injury experience for officeworkers at metal mines and mills during the period 1961-63 was 20 nonfatal disabling work injuries, (there were no fatal injuries reported), during an aggregate work-time of 28,694,244 man-hours. These injuries occurred at a frequency rate of 0.70 per million man-hours. There were no fatal injuries reported for officeworkers at non-ferrous smelters, refineries, and reduction plants during 1961-63, but seven nonfatal injuries were reported during an aggregate work-time of 30,814,772 man-hours. The frequency rate for these injuries was 0.23 per million man-hours for this period.

Jan 1, 1967

By J. E. Rourke, O&apos

A wide variety of techniques and equipment are available for coring soft or poorly consolidated geological material. This report presents a comprehensive literature review and evaluation of these techniques and equipment. A potential user will find guidelines in this report to assist him in selecting sampling equipment. A bar chart shows what samplers have been used under what geological conditions, and gives the specific literature references. Two matrices rate the present techniques and equipment with respect to reported success for sampling specific materials, and with respect to several performance characteristics including complexity of use and core quality. These matrices are supplemented with tables of typical sampling equipment. and program costs. Near-term future developments are seen primarily in improved training of drillers, and in instrumenting the drilling operation to provide objective data on drilling characteristics. An extensive annotated bibliography, a catalogue of equipment suppliers including specifications and cost ranges, and a list of manufacturers and distributors are appended to the report.

Jan 1, 1978

By Wm. F. Netzeband

"The mode of ore occurrence and the methods and costs of mining at one of the zinc-lead mines in the Tri-State zinc and lead district, Oklahoma, are presented in this paper for the information of mine operators in other districts.No. 2 mine property was acquired by lease in 1918 after some 30 holes had been drilled and a shaft had been sunk to the 305-foot level by the first lessees. After acquisition of the lease, the present operating company drilled a rich ore body on the 260-foot level and in 1920 started sinking two shafts. Production was begun late in 1921, and the mine has been operated more or less continuously to the present time.The mill has a capacity of 400 tons in 10 hours, the usual length of the mill shift in the district.The geology of Mine No. 2 is very similar to that of Mine No. 13 except that the Cherokee shale is thicker, ranging from 80 to 160 feet, and all the formations are correspondingly deeper, the Short Creek oolite horizon here being at a depth of about 300 feet. The oolite has not been found on this property, but the lime comes in at about the level at which the oolite should appear.The ore deposits of Mine No. 2 occur in the brecciated and bowlder ground above the Short Creek oolite. The main or 260-foot level is about 40 feet above the oolite horizon, and the lower or 300-foot level is immediately above it.The ore deposition is controlled by a zone of shearing and fracturing, and the mineable areas are divided into two distinct runs which have a northwest trend with a lean or practically barren area dividing them. This characteristic has controlled the mining to a large extent, for it enables the mine superintendent to locate the large pillars in lean ore and leave only small pillars in the richer ore. Figure 1 shows the outlines of the ore body and the pillars.The ore on the main level occurs disseminated throughout the jasperoid breccia as patches or lenses in the jasperoid, or cementing massive bowlders of jasperoid breccia and chert. The ore of the lower level is more of the bowlder type than that on the main level and occurs chiefly cementing the bowlders but also with some disseminated ore in the jasperoid breccia.The gangue minerals are jasperoid breccia, chert, and dolomite. Calcite is found in minor quantities. Sphalerite is the principal ore mineral; galena is found only in minor quantities around the edges of the ore body. When galena is encountered in this ore body, the limit of the ore can be expected.The exploration and estimation of ore reserves at Mine No. 2 are similar in many respects to the methods used at Mine No. 1.4After the mine was opened up and the general character of the ore deposit had been determined, drilling operations were concentrated along the trend of the shear zone. Later drilling has proved what appears to be a parallel shear zone or an offset of the zone now being mined."

May 1, 1929

By J. S. Coffman

Wyoming is estimated to have more than 700 million tons and Utah more than 2.5 billion tons of +10 percent P2O6 phosphate rock considered to have some future economic potential. In Wyoming, the +24 and +18 percent P205 rock potential resources total nearly 250 and 450 million tons, respectively. In Utah, the +31, +24, and +18 percent rock total approximately 33 million, 222 million, and 2.2 billion tons, respectively. These resources are all located above the local drainage levels and do not include latent resources. All of the mining and beneficiation of phosphate rock in the two States is done by San Francisco Chemical Co. The facilities include open pit mines at Vernal, Utah, and Leefe, Wyo.; an underground mine in the Crawford Mountains, Utah, and beneficiation plants at Leefe and Vernal. One of the principal markets for the phosphate rock is Western Phosphates, Inc., fertilizer plant at Garfield, Utah. Recent exploration and development has been under-taken by different companies in the Southeastern Wind River Range, Sublette Range, and Crawford Mountains. The facilities at Leefe and Vernal are in the process of expansion. Some of the areas of western Wyoming contain vast quantities of phosphate rock in minable units, but, because of their remote location, are classed as latent areas. In these areas, there are estimated to be about 700 million, 2 billion, and 3 billion tons of phosphate rock in the +24, +18, and +10 percent P205 grade classes, respectively. The Snake River Range of Idaho and Wyoming is also estimated to contain roughly 21, 106, 177, and 214 million tons of potential resources in the +31, +24, +18, and +10 grade categories, respectively. This area also contains a large amount of latent rock in the more remote areas.

Jan 1, 1967

By Lewis A. Martin

Researchers from the Spokane Research Laboratory, National Institute for Occupational Safety and Health, in cooperation with engineers from the Department of Mining and Geological Engineering, Montana Tech, Butte, MT, conducted tests to evaluate the tensile strength, fiber count, and adhesion of shotcrete applied to panels at the Chief Joseph Mine, a research and training facility operated by Montana Tech. The tests were conducted in the mine ramp 45 m (150 ft) inward from the access portal at a 15.25-m- (50-ft) long test area divided into five 3-m- (10-ft) long sections. The shotcrete was applied with an Aliva 240.5 machine fitted with a predampener. Different amounts of fiber were entrained for each panel. Background data for the tests were obtained from earlier tests in Nevada, where the typical amount of fiber in the shotcrete is 6.54 kg/m3 (11 lb/yd3). All shotcrete was applied to a minimum thickness of 76 mm (3 in). Cylindrical cores were drilled at the wall-rock interface, and adhesion was tested after 28 days of curing. The goal of this research is to reduce the need to install multiple supports at the advancing face by creating a safer mining system that limits the time miners are exposed to unprotected roof.

Jan 1, 2004

By Jonathan S. Kelly

Effective control of respirable dust is one of the most serious problems associated with longwall mining in the United States. This report describes the development and the underground evaluation of ventilated cutting drums, on a double ended ranging drum shearer. The ventilated drum uses high pressure (1,500 psi) water sprays to draw air (3,500 cfm) through 12 airmoving tubes mounted in the drum hub. The sprays draw dusty air from the face side of the drum, scrub the air, and discharge the clean air on the gob side of the drum against a deflector plate. During a three week underground evaluation, the cutting drums reduced shearer generated dust levels at the shearer operators position by 40%, at the shield operators downwind of the shearer by 55%, and at the tailgate by 55%. Cutting and loading performance of the drums were superior to the mine?s conventional drums. After the evaluation, the mine continued to use the ventilated drums to finish mining the panel. During this 3 month period, there were no mechanical or seal failures demonstrating excellent system reliability.

Jan 1, 1987

By J. R. Thoenen

Profits in the crushed-stone industry, as in any other, represent the difference between selling price and production cost. When consumer demand increases rapidly, as occurred in the crushed-stone industry from 1918 to 1927, selling prices tend to rise. Cost of production usually rises, also, owing to the expense of expanding facilities, searching for and developing new quarries, and purchasing, installing, and operating new equipment. Frequently, also, the inattention of managements to the details of operating costs is responsible for their increase. This is not due to negligence but rather to the necessity of confining attention to the problems involved in producing material to supply orders. When market conditions change and consumer demand becomes stabilized or contracts, the producer r s attention usually is directed to assuring the orders necessary to keep his enlarged facilities busy. Hence, competition increases and soiling prices decline.

Jan 1, 1939

By J. R. Thoenen

Profits in the crushed-stone industry, as in any other, represent the difference between selling price and production cost. When consumer demand increases rapidly, as occurred in the crushed-stone industry from 1918 to 1927, selling prices tend to rise. Cost of production usually rises, also, owing to the expense of expanding facilities, searching for and developing new quarries, and purchasing, installing, and operating new equipment. Frequently, also, the inattention of managements to the details of operating costs is responsible for their increase. This is not due to negligence but rather to the necessity of confining attention to the problems involved in producing material to supply orders. When market conditions change and consumer demand becomes stabilized or contracts, the producer's attention usually is directed to assuring the orders necessary to keep his enlarged facilities busy. Hence, competition increases and soiling prices decline.

Jan 1, 1939

By P. Wearden, K. Bryner, K. Vrana, V. Castranova, R. Dey, R. Reist, J. Blackford

"Summary: Fibroblast proliferation and enhancement of collagen synthesis are key steps in the development and progression of pulmonary fibrosis. The current investigation presents a fibroblast proliferation assay to detect the release of competence factors from pneumocytes. The specific objective of this study was to define cell culture conditions for fibroblasts that would allow selective detection of competence factors in test media. The results indicate the following: (a) fibroblasts should be cultured for 2 days in plasma-free medium rather than 2% plasma to assure complete quiescence; (b) 1% plasma was optimum for producing progression activity for the bioassay of a competence factor, while 0.5% plasma did not produce sufficient progression activity (yielding false negatives) and 2% plasma often contained significant competence activity (yielding false positives); and (c) fresh plasma should be used since the progression activity of plasma was adversely affected by freezing and thawing. Under these conditions, this bioassay can be employed with either rat or human lung fibroblasts to detect competence factors such as platelet-derived growth factor (PDGF), at levels as low as 25 ng/ml.Fibrotic lung disease, as a consequence of occupational exposure to silica dust. is characterized by the development of concentric hyalinized nodular lesions in the lung and the progressive loss of pulmonary diffusion capacity. Proliferation of pulmonary fibroblasts and enhanced synthesis of collagen by these pneumocytes have been shown to be key steps in the development of chronic silicosis ( 1 ). The regulation of lung fibroblast proliferation by cytokines released from alveolar macrophages may be an important pathogenetic mechanism in the development of the fibrotic process (2). Some cytokines stimulate fibroblast proliferation by activating specific phases of the cell cycle (3,4). In particular, platelet-derived growth factor (PDGF) promotes fibroblast proliferation by inducing the movement of quiescent (G0 ) cells into the G1 phase of the cell cycle (5). Insulin-like growth factor (IGF) and transforming growth factor-P (TGF-P). on the other hand, regulate the rate of transition of fibroblasts from G 1 into the S phase (5,6). These two classes of cytokines have been termed competence and progression factors, respectively. One approach used to examine the release of cytokines from macrophages is the fibroblast proliferation assay in which quiescent fibroblasts are exposed to culture supematants from macrophages exposed to various stimuli. In most of these assays, the supernatant contains fetal calf serum (FCS), which provides the competence factor(s) necessary to facilitate the proliferation of fibroblasts (7-9). Recently, a fibroblast proliferation assay using platelet-poor .plasma [lacking competence factor(s)] as a substitute for FCS bas been described (I 0, 11 ). In this assay, the release of a competence-inducing PDGF-like growth factor from rat and human macrophages can be distinguished from other cytokines that act as progression factors."

Mar 1, 1992