Biomedical subjects

M H May

Publications and source records attributed to M H May.

At least 19 recordsLinked to original sources

PubMed2000

Making microencapsulation work: conformal coating, immobilization gels and in vivo performance.

Microencapsulation of cells as a means of insulin or other protein delivery (for example, for gene therapy) has not yet realized its potential. Three aspects of this problem are illustrated with reference to the use of poly(hydroxyethyl methacrylate-co-methyl methacrylate) (HEMA-MMA). Conformal coating was used to coat cell aggregates with a very thin layer of a water-insoluble HEMA-MMA membrane that conforms to the shape of the aggregate, and minimizes the polymer's contribution to the total transplant volume. Cell aggregates were coated at a liquid-liquid interface of a discontinuous density gradient composed of both aqueous and organic liquids. Aggregates of HepG2 cells were coated and remained viable. Immobilization matrices were co-encapsulated in order to control cell phenotype. Ultralow gelling temperature agarose promoted the proliferation of HEK293 cells, while the viability of transfected C2C12 cells was improved in microcapsules that contained Matrigel. Rat or human hepatoma cells in HEMA-MMA microcapsules lost viability within a week after implantation into an omental pouch in Wistar rats. The loss of viability was attributed to the tissue reaction, although it is not clear if the cells lost their viability in vivo leading to the aggressive tissue reaction or if the latter caused the cells to starve or otherwise die. On the other hand, intraperitoneal implantation of microcapsules containing L929 cells in 'syngeneic' C3H mice in a high-strength agarose gel resulted in maintenance of viability of approximately 50% of the encapsulated cells. While progress is being made on several fronts, this type of tissue engineering construct is still several years away from routine use in humans.

Animals↗

PubMed1999

Conformal coating of small particles and cell aggregates at a liquid-liquid interface.

Polymer encapsulation of allogeneic or xenogeneic tissue is under active investigation as a means of isolating transplanted cells, such as pancreatic islets, from the immune system. We report here a method for coating small particles and cell aggregates with a very thin water insoluble hydroxyethyl methacrylate-methyl methacrylate (HEMA-MMA) membrane that conforms to the shape of the aggregate, and minimizes the polymer's contribution to the total transplant volume. Cell aggregates were coated at a liquid-liquid interface of a discontinuous density gradient composed of both aqueous and organic liquids. By increasing the viscosity difference and decreasing the density difference between the two liquids of the coating interface, coatings from approximately 1 to 15 microns thick were formed. Aggregates of HepG2 cells and pancreatic islets were coated and remained viable.

Biocompatible Materials↗

PubMed1997

Synthesis and use of a substrate for the detection of isopeptidase activity.

We have developed a substrate to assay for an isopeptidase, an enzyme capable of cleaving the Nepsilon-(gamma-glutamic) lysine bond which crosslinks polypeptide chains. This substrate consists of modified lysine (N-alpha-[3H]acetyl-l-lysine-N-methylamide or ALMA), linked by its epsilon-amino group to a gamma-carboxyl amide group of casein with guinea pig liver transglutaminase or Factor XIIIa. We used this substrate to demonstrate the release of [3H]ALMA from [3H]ALMA-casein in a culture medium of Bacillus cereus and in brain homogenates of 12- to 14-day-old embryonic chicks. The prokaryotic and the eukaryotic enzymes resemble each other in that both are activated by Ca2+ or Mg2+ and by alkaline phosphatase and both are inhibited by ATP. The [3H]ALMA-casein is a sensitive substrate able to measure reliably specific activities as low as 10(-8) micromol of [3H]ALMA/min/microg protein. The special advantage of this substrate is that the initial rate of ALMA-casein cleavage is not affected significantly by the levels of protease contaminants we have encountered. We were able to rule out alternative mechanisms such as gamma-glutamyl transpeptidase, gamma-glutamyl cyclotransferase, and the reversal of transglutaminase. We conclude that an isopeptidase mechanism most plausibly accounts for the ALMA release.

Animals↗

PubMed1994

Hypertriglyceridemic serum, very low density lipoprotein, and iron enhance Mycobacterium avium replication in human macrophages.

The growth of Mycobacterium avium 7497, serovar 4, in cultured human macrophages is enhanced by Fe3+ and serum lipids over 7 days. Iron (1-80 micrograms/mL) added to macrophages cultured in normal serum resulted in 10-fold increases in growth. If iron-supplemented macrophages were cultured in serum from hypertriglyceridemic donors after infection, M. avium growth increased 10(3)- to 10(4)-fold. Without macrophages, differences in bacterial growth between sera were not seen. Removal of very low density lipoprotein (VLDL) eliminated the differences between sera. Isolated VLDL from hyperlipidemic serum resulted in 10(5)-fold increases in growth over that seen with VLDL from normal sera. Accelerated M. avium growth in macrophages cultured with hyperlipidemic serum was partly inhibited by the addition of superoxide dismutase (1000 IU/mL). Results suggest that iron stimulates O2-induced oxidation of VLDL and its subsequent accumulation in macrophages. The resultant iron- and lipid-laden cells become excellent hosts for mycobacterial growth.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Transferrin, iron, and serum lipids enhance or inhibit Mycobacterium avium replication in human macrophages.

Mycobacterium avium grows exponentially over 7 days in human macrophages when they are cultured in serumless medium. Normal serum inhibits this replication. When serum lipids were extracted using chloroform, the inhibitor was present in the lipid-free component. The lipid extract significantly enhanced M. avium replication. Iron (Fe2+) added at 8-80 micrograms/mL to infected macrophage cultures in serum resulted in enhanced mycobacterial replication. Serum-induced inhibition of bacterial growth in serumless medium could be duplicated with apotransferrin at 50-500 micrograms/mL. At 1000 micrograms/mL, apotransferrin no longer inhibited bacterial growth. Holotransferrin was not inhibitory, and at 500 micrograms/mL, it enhanced M. avium growth. Depletion of the transferrin in serum by affinity chromatography using goat anti-transferrin on protein G-Sepharose removed inhibitory activity. These results indicate that transferrin levels, transferrin saturation, iron levels, and serum lipids can profoundly alter the replication of M. avium in association with macrophages.

Adult↗

PubMed1992

Characterization of inhibition of Mycobacterium avium replication in macrophages by normal human serum.

Serum from some AIDS patients permits the rapid multiplication of Mycobacterium avium in cultured human macrophages. Serum from human immunodeficiency virus-negative individuals inhibits replication. The characteristics of the serum-induced inhibition were examined here. M. avium 7497 serovar 4 grew exponentially in macrophages when they were cultured in serumless medium. Growth was measured by determining the CFU after infected macrophages were lysed at 0 to 7 days after infection. Normal AB serum (5 to 10%) added to infected macrophages resulted in an initial 4-day lag of bacterial growth followed by rapid replication from 4 to 7 days. Serum also inhibited bacterial replication in medium without macrophages. This inhibition was not biphasic but was sustained over 7 days. Macrophage-associated M. avium became less responsive to serum inhibitor within 24 h after infection of macrophages. Within 2 days of culture, M. avium no longer responded to inhibitor. Replication of macrophage-derived M. avium (Vi) was in some instances serum inhibitable and at other times was enhanced by serum, when it was used to infect fresh macrophages. The Vi phenotype remained serum inhibitable without macrophages. Preinfection of macrophages with heat-killed M. avium did not alter serum-induced bacterial inhibition or escape from inhibition.

Blood Physiological Phenomena↗

PubMed1992

Comparison of the abilities of Mycobacterium avium and Mycobacterium intracellulare to infect and multiply in cultured human macrophages from normal and human immunodeficiency virus-infected subjects.

Patients with AIDS commonly develop disseminated infections with Mycobacterium avium (MA) but not its close relative, M. intracellulare (MI). In non-AIDS patients who have these infections, the two species are about equally distributed. The higher incidence of infection with MA than with MI in AIDS patients might be due to the selective susceptibility of these patients to MA. This possibility was tested by comparing the abilities of MA and MI to infect and replicate in cultured macrophages from normal subjects and from patients with AIDS-related complex or AIDS. The macrophages were cultured in medium supplemented with 1 or 5% normal or patient sera or with 1% defined serum substitute. Replication of MA (serovar 4) or MI (serovars 16 and 17) in the macrophages was measured by CFU counts made from lysed samples of the macrophages taken at 0,4, and 7 days after macrophage infection. MA and MI in infected normal macrophages which were cultured in normal serum replicated in these macrophages at similar rates. MA but not MI multiplied abnormally rapidly in patient macrophages cultured in either normal serum or patient serum. The accelerated growth of MA in patient macrophages was macrophage dependent, because patient sera did not change the rate of MA replication in culture medium lacking macrophages. However, patient sera did increase the permissiveness of normal macrophages to MA but not MI. These results suggest that a selective increased susceptibility to MA compared with a retained normal resistance to MI in human immunodeficiency virus-infected patients as they progress from AIDS-related complex to AIDS accounts for the higher prevalence of MA than MI infection in AIDS patients. The results also indicate that the mechanisms of native resistance in human macrophages to MA and MI are different.

Adult↗

PubMed1992

Chlorpromazine: a drug potentially useful for treating mycobacterial infections.

Chlorpromazine (CPZ) is one of several phenothiazines known to have antimicrobial properties. It can inhibit mycobacteria, and was reported in the early literature to improve tuberculosis clinically. CPZ was tested here for its ability to inhibit the replication of Mycobacterium tuberculosis and Mycobacterium avium in cultured normal human macrophages, as determined by counts of viable bacteria at 0, 4, and 7 days after bacterial infection of the macrophages. CPZ inhibited the intracellular bacteria at a concentration range of 0.23-3.6 micrograms/ml, and was more effective intracellularly than extracellularly. It was further tested for its ability to cooperate with isoniazid, streptomycin, pyrazinamide, rifampin, rifabutin, penicillin and ethambutol (EMB) against intramacrophage M. tuberculosis and M. avium. CPZ enhanced the effectiveness of most of the drugs tested against intracellular mycobacteria. However, the combination of CPZ and EMB did not result in augmented antimycobacterial activity.

Antitubercular Agents↗

PubMed1991

Evidence that vesicles containing living, virulent Mycobacterium tuberculosis or Mycobacterium avium in cultured human macrophages are not acidic.

Mycobacterium tuberculosis and Mycobacterium avium multiply in cultured human macrophages (MP) within membrane-enclosed vesicles. These vesicles are generally assumed to be acidic. The evidence most frequently cited for this assumption is that pyrazinamide, which requires an acid pH to be effective, is effective and streptomycin, which loses most of its activity at a low pH, is poorly effective against tubercle bacilli. This assumption was tested by using the two weak bases chloroquine and NH4Cl to raise the pH of acidic vesicles in MP experimentally infected with M. tuberculosis or M. avium. An immunocytochemical locator of acidic regions in the MP was used to monitor the association of intracellular bacilli with acidity. MP were infected with M. tuberculosis or M. avium and incubated with various combinations of the drugs and the weak bases. Replication of the bacteria in the MP was measured by culture counts. Intracellular associations of the mycobacteria with acidity were assessed by electron micrographs and by using the weak base 3-(2,4-dinitroanilino)-3'-amino-N-methyl dipropylamine, which was detected with colloidal gold-labeled antibodies. It was confirmed by immunocytochemistry that both chloroquine and NH4Cl raise the pH of acidic vesicles in the infected MP. However, neither caused any pH-related change in the antimycobacterial activities of pyrazinamide or streptomycin or of the pH-independent drug isoniazid. Immunochemical analyses showed acidity to be associated with killed but not living mycobacteria in the MP. These findings suggest that living M. tuberculosis and M. avium are located in human MP in vesicles which are not acidic.

Ammonium Chloride↗

PubMed1990

Inhibition of tubercle bacilli in cultured human macrophages by chloroquine used alone and in combination with streptomycin, isoniazid, pyrazinamide, and two metabolites of vitamin D3.

Intracellular tubercle bacilli (TB) reside in vacuoles in infected human macrophages (MPs). The relative impotency of streptomycin against TB in MPs and the contrary greatly increased potency of pyrazinamide (PZA) have been attributed to the fact that these vacuoles are phagolysosomes and, therefore, acidic. Chloroquine (CQ) is a lysomotropic base which can be used to raise phagolysosomal pH. Consequently, it was tested for its ability to increase the anti-TB effectiveness of streptomycin and decrease that of PZA in cultured human MPs. MPs infected with virulent Erdman strain TB were incubated in medium with various combinations of the drugs. Samples were taken at 0, 4, and 7 days and lysed for CFU counts of viable TB on nutrient agar. As expected, CQ increased the effectiveness of SM, but unexpectedly, it did not decrease that of PZA. CQ alone was found to be able to inhibit intracellular TB. Because of this, it was also tested with isoniazid, 1,25(OH)2-vitamin D3, and 25-OH-vitamin D3. It significantly enhanced the anti-TB protectiveness of both isoniazid and 25-OH-vitamin D3. Some combinations of CQ and the various drugs tested were able to kill intracellular TB. These results suggest that CQ may be useful in the treatment of tuberculosis.

Adult↗

PubMed1989

1,25(OH)2-vitamin D3 synergizes with pyrazinamide to kill tubercle bacilli in cultured human macrophages.

Pyrazinamide (PZA) is believed to be mycobactericidal in vivo. Because it is ineffective at neutral pH in vitro, it is thought to owe its in vivo activity at least partly to acting upon tubercle bacilli (TB) in the helpfully low pH of macrophage (MP) phagolysosomes. However, when it was tested in TB-infected cultured human MP, it was not bactericidal and was able only to slow intra-MP bacillary growth. Recent evidence has suggested that human MP need hormonal support from certain vitamin D metabolites to resist TB. This support was not provided in the culture medium of the earlier experiments in which the PZA was relatively ineffective. Here, PZA has been retested in MP cultured in medium supplemented with the hormonally active metabolite of vitamin D, 1,25(OH)2-vitamin D3 (1,25D3). The MP were infected with virulent TB and incubated in various concentrations of PZA. 1,25D3 was added to postinfection medium at 4 micrograms/ml. Inhibition or killing of intracellular TB was quantitated by counts of culturable TB from samples of lysed MP taken at zero, 4, and 7 days after MP infection. Previous evidence for the protectiveness of 1,25D3 alone for human MP against TB was confirmed. The weak inhibition of TB in MP by PZA alone also was confirmed. The two used together synergized to decrease concentrations of PZA which were inhibitory and to switch the action of PZA from weakly inhibitory to bacteriostatic or mildly bactericidal. 1,25D3 had no direct anti-TB effect, and it did not synergize with PZA in the absence of MP, as determined with acidified bacteriologic culture medium in the BACTEC radiometric system.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Effects of isoniazid and of ceforanide against virulent tubercle bacilli in cultured human macrophages.

Isoniazid (INH) is said to inhibit tubercle bacilli equally well in vivo and in vitro, and to be mycobactericidal. Ceforanide (CEF) can inhibit tubercle bacilli in vitro but has been found ineffective clinically. These two drugs were tested against virulent tubercle bacilli in cultured human macrophages (MP), partly to compare the results with clinical experience, and partly for a better understanding of antituberculosis activities of these drugs in human beings. INH had the same minimal inhibitory concentration (MIC) against tubercle bacilli in MP as in 7H9 broth cultures. It killed multiplying bacilli in MP but not nonmultiplying bacilli, even at 100 times MIC. It killed both multiplying and nonmultiplying bacilli in broth cultures. It interfered with its own effectiveness against intra-MP bacilli by preventing nonmultiplying bacilli from beginning to multiply and thus become susceptible to killing. These findings help explain why this demonstrably mycobactericidal drug produces relapses of tuberculosis when used alone. It was confirmed that CEF is able to inhibit growth in broth cultures (MIC = 10 micrograms/ml). However, it was not effective against either multiplying or nonmultiplying bacilli in MP at concentrations up to 50 micrograms/ml. These results with the drugs INH and CEF support the good record of correlation between the human MP model of tuberculosis and clinical experience in antituberculosis chemotherapy.

Adult↗

PubMed1988

Effectiveness of ofloxacin against Mycobacterium tuberculosis and Mycobacterium avium, and rifampin against M. tuberculosis in cultured human macrophages.

Ofloxacin (OFL) is a new broad-spectrum drug with potentially valuable antimycobacterial activity. It was tested for ability to inhibit virulent tubercle bacilli (TB) and virulent Mycobacterium avium in cultured human macrophages (MP). The first-line antituberculosis drug rifampin (RMP) also was tested against TB in MP. The drugs were added to the MP cultures immediately after infection or 2 days later. Antimicrobial inhibition was measured by colony-forming-unit (cfu) counts of bacilli from lysed samples of the infected MP taken at zero, 4, and 7 days after infection. Drug inhibition of the bacteria in vitro in 7H9 broth also was measured. OFL showed the same minimal inhibitory concentration (MIC) of 1.25 micrograms/ml against TB in vitro and in MP. At 2 micrograms/ml or more it killed TB in vitro and in MP. It was equally effective in MP against initially nonmultiplying TB and MP-established TB, which were multiplying exponentially in the MP. OFL had the same MIC in vitro against M. avium but was ineffective against both M. avium in MP and M. avium isolated directly from MP at as much as 8 micrograms/ml. The MIC for RMP against TB in MP was 0.1 microgram/ml, and TB in vitro 0.02 microgram/ml. At 0.5 microgram/ml or greater, it killed TB in MP. RMP killed TB in MP rapidly, whereas OFL killed them slowly. These results confirm initial clinical evidence, as published by others, that OFL should be a useful antituberculosis drug. However, they suggest that it may not be very effective against MA infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗

PubMed1987

Inhibition by 1,25(OH)2-vitamin D3 of the multiplication of virulent tubercle bacilli in cultured human macrophages.

Historically, sunlight has seemed to fortify antituberculosis resistance. Evidence is presented here suggesting a role for vitamin D in this effect. The active metabolite of this photosynthesized vitamin, 1,25-dihydroxy-vitamin D3 (1,25D), promotes maturation and activation of human monocytes and macrophages (MPs). Therefore, it was tested for ability to protect MPs against virulent tubercle bacilli. MPs were derived by 7-day culture from blood monocytes, infected with the bacilli, and exposed to 1,25D in several regimens. Their inhibition of bacilli was measured by lysing samples of the cultures at 0, 4, and 7 days after infection and making bacillary CFU counts from serial dilutions of the lysates. 1,25D enabled MPs to slow or stop bacillary replication. Autologous serum supported the 1,25D-induced protection because the vitamin was not effective in medium supplemented with a serum substitute and was less effective in a heterologous AB serum than in autologous serum. The protection developed rapidly and could be induced even when 1,25D was added 3 days after infection. A concentration on the order of 4 micrograms/ml was needed for protection by the regimens used in these experiments. That is considerably higher than normal circulating concentrations of 1,25D but could be reached in infectious granulomas, because MPs can make 1,25D from precursor 25-hydroxyvitamin D3. The precursor circulates at levels 10(3) higher than those of 1,25D and is directly influenced by dietary intake or photosynthetic production of vitamin D. These results identify 1,25D as an immunomodulator which can reproducibly activate human MPs to express tuberculoimmunity. They connect vitamin D, sunlight, and tuberculoimmunity and suggest that vitamin D should be considered a vital factor in the practical control of tuberculosis.

Calcitriol↗

PubMed1986

Comparison of 15 laboratory and patient-derived strains of Mycobacterium avium for ability to infect and multiply in cultured human macrophages.

Mycobacterium avium is a cause of nontuberculous chronic granulomatous infections which is attracting increased attention as a frequent opportunistic pathogen in acquired immunodeficiency syndrome. Some important aspects of its human pathogenicity were investigated by using cultured human macrophages infected with it. The uptake and replication of various strains of M. avium in the macrophages could be measured by CFU counts of the bacteria in samples of lysed, sonicated macrophages. Microscopic counts of acid-fast bacilli were not useful because the bacteria multiplying in the macrophages were usually not acid fast. Electron microscopy showed the intracellular bacilli to multiply by transverse fission, to be surrounded in individual vacuoles by a broad electronlucent zone, and to have thinner cell walls than extracellularly grown M. avium. Fifteen strains, including examples of serovars 1, 2, 4, 8, and 9, were studied for uptake and rate of replication in cultured macrophages from three normal subjects. The strains were isolates from patients with nontuberculous granulomatous infection, acquired immunodeficiency syndrome, or unrelated problems, or they were laboratory reference cultures. There were no differences among them in phagocytosis, but there were differences in intracellular replication. Laboratory strains tended to be avirulent, that is, they did not replicate in the macrophages. Patient isolates usually were virulent and could be compared for virulence by intracellular replication rates. Virulence correlated with flat, transparent bacterial colony morphology on nutrient agar but not with serovar or kind of patient from whom the bacteria were isolated. However, among strains of transparent colony morphology there were wide differences in virulence. A virulent bacilli generally produced domed, opalescent colonies on nutrient agar. A virulent bacilli predominated in populations of M. avium conditioned to growth in bacteriologic culture medium. Bacilli of virulent colony morphology predominated in populations passaged through cultured macrophages. The model described here presents a new approach to the investigation of the pathogenicity of M. avium for human subjects and may be more patient relevant than animal models.

Acquired Immunodeficiency Syndrome↗

PubMed1986

Inhibition by pyrazinamide of tubercle bacilli within cultured human macrophages.

Pyrazinamide (PZA) is a unique antituberculosis drug because it is effective in vivo but not in mediums commonly used to culture tubercle bacilli. Consequently, it was employed to test the validity of an in vitro macrophage model of human tuberculosis for value as a correlate of clinical events. The drug was as active in the macrophage model as it was clinically, inhibiting virulent tubercle bacilli at concentrations at 20 micrograms/ml or higher. By contrast, it was ineffective in 7H9 bacteriologic culture medium, even at concentrations as high as 2,560 micrograms/ml. It could be either bacteriostatic or bactericidal against intramacrophage tubercle bacilli, depending on its concentration, the donor of the macrophages, and the length of exposure of the infected macrophages to the drug. The data presented suggest that the clinical effectiveness of PZA is determined by a complicated self-modulating sequence of interactions between it, tubercle bacilli, and host macrophages. Specific evidence was found that tubercle bacilli may replicate within human macrophages in non-acid-fast form, thus indicating that colony-forming unit counts are inherently more accurate than acid-fast bacilli counts in these experiments, and also suggesting that important changes in bacillary cell wall composition may occur among tubercle bacilli within infected human macrophages.

Adult↗

PubMed1985

The effect of ethambutol on tubercle bacilli within cultured human macrophages.

Ethambutol (EMB) generally is believed to be clinically mycobacteriostatic. This concept was reexamined in an in vitro model of human tuberculosis that has direct relevance to in vivo effects in human subjects. Cultured human monocyte-derived macrophages infected with virulent Erdman tubercle bacilli were treated with EMB, and the resulting antimycobacterial consequences were measured by counts of acid-fast bacilli and bacterial colony-forming units. When added immediately after infection of the macrophages, EMB inhibited and killed tubercle bacilli within the cells at the same concentrations as it did in bacteriologic culture medium. When added 2 days after infection, it first appeared to increase the viable bacillary count above control culture levels, then killed intramacrophage bacilli at lower concentrations than in bacteriologic culture medium. We speculate that this occurs because macrophages enhance EMB effectiveness by killing tubercle bacilli, which have defective cell walls due to the effects of the drug. The concentrations of EMB that proved mycobactericidal in human macrophages are readily achieved clinically. The purported lesser antituberculosis effectiveness of EMB when compared to other bactericidal agents may be due to its less direct and efficient mode of killing tubercle bacilli, and the necessity therefore, for stricter maintenance of effective drug concentrations in vivo.

Adult↗

PubMed1984

Inhibition by streptomycin of tubercle bacilli within cultured human macrophages.

The strategy for using streptomycin against tuberculosis assumes that it is not effective intracellularly. But according to animal cell experiments, this is probably incorrect. We retested this assumption with a new experimental model using cultured human macrophages infected with tubercle bacilli so that the results would be directly relevant to human disease. At 5 and 50 micrograms/ml, streptomycin inhibited the bacilli strongly and killed some; at the lowest tested concentration of 0.5 micrograms/ml, it inhibited them weakly. It was acting intracellularly, because it could inhibit even when added 2 days after the macrophages had been infected and washed free of extracellular bacilli, and because in our experimental model the bacilli were shown to be unable to multiply extracellularly. However, as has been reported for animal macrophages, the antibiotic was quantitatively more than 2 orders of magnitude less effective in human macrophages than in simple bacteriologic medium. Probably this is because streptomycin is concentrated within lysosomes where low pH greatly inhibits it. The human macrophage-tubercle bacillus chemotherapeutic bioassay we describe here for the first time could be a superior patient-consonant new method for testing antituberculosis agents and treatment regimens. It retains important in vivo features, the complete host cell-parasite relationship for instance, without giving up the in vitro advantages of rapidity and objectivity.

Cells, Cultured↗