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Freedman ML. Anemia in the elderly. COMPREHENSIVE THERAPY 1983; 9:45-53. [PMID: 6883979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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202
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Freedman ML, Guggenheim B. Dextran-induced aggregation in a mutant of Streptococcus sobrinus 6715-13. Infect Immun 1983; 41:264-74. [PMID: 6190754 PMCID: PMC264773 DOI: 10.1128/iai.41.1.264-274.1983] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A mutant of wild-type Streptococcus sobrinus 6715-13 has been isolated which resists aggregation by exogenous dextran. This variant is able to form adherent plaque deposits in vitro when cultured in the presence of sucrose and has dextranase activity. In these respects it is the complement of previously described isolates which are plaque formation defective but aggregation normal. Measurements of the incorporation of glucose from glucosyl-labeled sucrose into glucan by cell-associated glucosyltransferase enzyme activity and the thermal labilities of catalytic and receptor functions, as well as the binding of labeled dextrans to the cells, provide evidence that neither dextranase nor glucosyltransferase is the receptor involved in dextran-induced aggregation. Blockage of such bacterial aggregation by anti-glucosyltransferase or anti-dextranase sera suggests cross-reactivity between the antigenic determinants of proteins which recognize alpha(1-6) glucan linkages. A model is proposed, consistent with these and previous findings, in which enzymatic function precedes dextran receptor activity in emergence from the cell. It is also proposed that dextran receptor components of the multireactive glucosyltransferase enzyme(s) and dextranase(s) are spatially separate from, although functionally and antigenically related to, the receptors on the bacterial surface involved in dextran-induced aggregation.
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203
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Freedman ML. Common hematologic problems: diagnosis and treatment. Geriatrics (Basel) 1983; 38:119-23, 127-30, 134. [PMID: 6832586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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204
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Finkelstein MS, Petkun WM, Freedman ML, Antopol SC. Pneumococcal bacteremia in adults: age-dependent differences in presentation and in outcome. J Am Geriatr Soc 1983; 31:19-27. [PMID: 6848574 DOI: 10.1111/j.1532-5415.1983.tb06283.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In order to evaluate the effect of age on the presentation of and response to acute bacterial infection, the hospital charts of 187 adult patients with community-acquired pneumococcal bacteremia admitted to Bellevue Hospital over a nine-and-a-half year period were reviewed. Compared with younger patients, older patients (aged 65 or older) more frequently had (1) a lower fever in response to the infection, (2) an unclear history of illness, (3) a delay in diagnosis and/or therapy, and (4) a higher risk of dying. On admission, their leukocyte counts and heart rates were similar to those in a group of younger patients, which was composed largely of alcoholic patients and those addicted to intravenous drugs. Response to therapy was also similar in surviving older patients. Lower temperature and an unclear history were features most commonly associated with both delayed diagnosis and higher mortality. When patients with a history of alcohol abuse and those dying shortly after admission (i.e., presenting in a moribund state) were eliminated from the analysis, many of these age-related differences in presentation and outcome became even more evident.
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Freedman ML. Anemias in the elderly: physiologic or pathologic? HOSPITAL PRACTICE (HOSPITAL ED.) 1982; 17:121-9, 133-6. [PMID: 6979503 DOI: 10.1080/21548331.1982.11702313] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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207
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Freedman ML, Coykendall AL, O'Neill EM. Physiology of "mutans-like" Streptococcus ferus from wild rats. Infect Immun 1982; 35:476-82. [PMID: 6276304 PMCID: PMC351065 DOI: 10.1128/iai.35.2.476-482.1982] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Strains of Streptococcus ferus isolated from the oral cavities of wild rodents inhabiting sucrose-rich and sucrose-poor environments have many traits in common with the "mutans" streptococci. Thus, S. ferus HD3 and 8S1, like cariogenic S. sobrinus 6715-13, from adherent, alpha (1 leads to 3) glucopyranosyl-glucose linkage-rich, plaquelike deposits in vitro and in vivo through the action of constitutive glucosyltransferase(s) enzymes on sucrose, produce and degrade intracellular polysaccharide, produce short-chain fatty acids from the catabolism of mono- and disaccharides, carry the c antigen of S. mutans, and penetrate, persist, and proliferate in a sucrose-augmented fashion in the oral cavities of specific-pathogen-free rodent caries models. However, unlike infection with common S. mutans, infection with tested S. ferus strains does not cause caries. This avirulence appeared to result more from the reduced aciduricity of S. ferus than from differences in glucosyltransferase complements. Studies showed that despite generally similar growth rates and extracellular glucan syntheses, the acidogenic metabolism of S. ferus was more inhibited by declining environmental pH than was cariogenic S. sobrinus 6715-13 and that, in vitro, less hydroxyapatite was solubilized by S. ferus metabolic end products. The physiology of these S. ferus strains demonstrated that, in addition to plaque formation and acid production, acid tolerance was crucial to the carious process.
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208
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Marcus DL, Lew G, Gruenspecht-Faham N, Freedman ML. Effect of inhibitors and stimulators on isolated liver cell mitochondrial protein synthesis from young and old rats. Exp Gerontol 1982; 17:429-35. [PMID: 7183450 DOI: 10.1016/s0531-5565(82)80004-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Mitochondria isolated from the livers of old rats (26-30 months) were found to incorporate 41% less leucine into mitochondrial proteins as compared to those from young rats (2-3 months). The initial rates of incorporation of label were 145 cpm/mg/min for the "old" animals, and 320 cpm/mg/min for the young animal. No difference in either amino acid pool size or leakage of label through the mitochondrial membrane was detected in the two age groups. Young rats were treated in vivo with cycloheximide (10 mg/kg) followed by isolation and incubation of their mitochondria in vitro two hours later. There was a two-fold increase in incorporation of leucine into mitochondrial proteins. In contrast, mitochondria isolated from old rats showed a markedly blunted response to cycloheximide pre-treatment. When mitochondria isolated from young and old rats were exposed to inhibitors of mitochondrial protein synthesis, alpha-alpha-dipyridyl (2 x 10(-4)M) and ethanol (0.15M), the old mitochondria showed greater susceptibility to inhibition. These results suggest that the control of the biosynthesis of mitochondrial proteins is altered in the old animals.
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209
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Tanzer JM, Fisher J, Freedman ML. Preemption of Streptococcus mutans 10449S colonization by its mutant 805. Infect Immun 1982; 35:138-42. [PMID: 6459292 PMCID: PMC351007 DOI: 10.1128/iai.35.1.138-142.1982] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Oral infection of rats with Streptococcus mutans mutant 805 was used to prevent the establishment of its highly virulent wild-type progenitor NCTC 10449S. The dose of wild-type cells required to colonize 100% of the specific pathogen-free Osborne-Mendel rats (21 to 43 days old) consuming caries test diet 2000 was greater than 4 x 10(5) but less than 4 x 10(6) cells. Therefore, the latter dose was used to challenge rats which had already been colonized by an oral dose of about 6 x 10(8) cells of mutant 805. This prior infection by 805 either completely protected rats from subsequent colonization by wild-type cells or greatly delayed and diminished their emergence. Rats in which wild-type cells became established showed much lower percentages of wild-type cells in their total recoverable floras than did rats that were not first infected by the mutant. Large doses of mutant 805, however, did not displace wild-type cells from rats once it became established. There was no evidence of reversion of the mutant, which is defective in intracellular polysaccharide synthesis and hence is less virulent than wild-type cells. The data indicate that the S. mutans cell which first colonizes rats gains the strongest ecological position and is difficult to displace. Also, they suggest the possible prophylactic utility of infection by this mutant of S. mutans.
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210
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Marcus DL, Ibrahim NG, Freedman ML. Age-related decline in the biosynthesis of mitochondrial inner membrane proteins. Exp Gerontol 1982; 17:333-41. [PMID: 7169093 DOI: 10.1016/0531-5565(82)90033-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Isolated mitochondria from rat livers of various ages show a gradual decline in the rate of inner membrane-matrix protein synthesis with advancing age of the animal. Rats at 112-120 weeks synthesize these proteins at only 40% of the rate of 2-8-week-old animals. The initial rates of incorporation of label were 145 cpm/mg/minute for the "old" animals, and 320 cpm/mg/minute for the "young" animal. No difference in either amino acid pool size or leakage of label through the mitochondrial membrane was detected in the two age groups. Treatment of the mitochondria with ferrous ammonium sulphate produced a 1.62 fold increase in mitochondrial protein synthesis in the young animal but not in the old. Hemin treatment produced a similar effect. These results suggest that the decrease in delta-aminolevulinic acid synthase activity seen with age (Paterniti et al., 1978) may be due to a decrease in the synthesis of mitochondrial inner membrane proteins.
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211
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Finkelstein MS, Freedman ML, Shenkman L, Krugman S. Evidence of prior hepatitis B and hepatitis A virus infections in an ambulatory geriatric population. JOURNAL OF GERONTOLOGY 1981; 36:302-5. [PMID: 6262400 DOI: 10.1093/geronj/36.3.302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Ninety-five randomly selected patients attending an ambulatory geriatric medical clinic were tested for the presence in their sera of hepatitis B surface antigen and of antibody to hepatitis B and A viruses. Such evidence of past hepatitis infection was correlated with current liver function and history of having received blood transfusions. The results showed that 94% of patients had antibody to hepatitis A virus, and 32% had antibody to hepatitis B virus. Patients with abnormal liver function tests, or those with a history of blood transfusions were no more likely to have hepatitis B antibody than patients with normal liver function tests or those with no history of transfusion.
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212
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Abstract
Streptococcus ferus, which is indigenous to wild rats, is a member of the mutans group of streptococci. We tested its ability to colonize and to cause caries in laboratory rats by comparing two strains of S. ferus with the very cariogenic Streptococcus sobrinus strain 6715. Groups of rats were fed either finely ground mouse chow or a 56% sucrose diet, or they were switched from chow to the sucrose diet. All three strains colonized the mouths of rats regardless of diet. However, the infectants reached higher proportions of the total flora more quickly in the rats consuming sucrose. Similarly, the percentage of the oral flora represented by an infecting organism increased numerically when rats originally fed chow were switched to the sucrose diet. S. ferus formed plaques on the teeth of the rats, but these plaques did not proliferate over smooth tooth surfaces as extensively as did those of S. sobrinus. Although S. ferus colonized and accumulated, it was non-cariogenic in rats fed sucrose compared both with rats fed similarly but infected with S. sobrinus 6715 and with uninfected controls. In vitro measurements suggested the S. ferus produced acid less rapidly than S. sobrinus. Thus, the lack of cariogenicity in S. ferus may result from an inability to form copious plaques on smooth tooth surfaces and from low acid production and, therefore, may represent a natural absence of the pathogenic potential usually inherent in the mutans streptococci.
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Abstract
There is currently a controversy of whether elderly people (over age 65) have an age-related physiologic decline in red cell parameters. If this is so, a new normal range might be established for geriatric patients, as has been suggested by others. However, since anemia is often the first sign of severe illness in a patient, new normal values might include a danger of overlooking patients with true anemia secondary to an underlying disease. In this article we shall review what is known about red cell parameters in elderly patients and attempt to answer the questions of whether new geriatric norms should be established.
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214
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Freedman ML, Cunningham PM, Schindler JE, Zimmerman MJ. Effect of lead speciation on toxicity. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 1980; 25:389-393. [PMID: 7426787 DOI: 10.1007/bf01985543] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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215
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Marcus DL, Ibrahim NG, Gruenspecht N, Freedman ML. Iron requirement for isolated rat liver mitochondrial protein synthesis. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 607:136-44. [PMID: 7370259 DOI: 10.1016/0005-2787(80)90227-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Isolated rat liver mitochondrial protein synthesis was severly inhibited by alpha, alpha-dipyridyl (a ferrous iron-chelating agent), chloramphenicol and hemin (10(-7) M or greater). In contrast, gamma, gamma-dipyridyl (a non-iron-chelating analogue of alpha, alpha-dipyridyl), cycloheximide and lower concentrations of hemin were non-inhibitory. The inhibitory action of alpha, alpha-dipyridyl was reversed by addition of Fe(NH4)2(SO4)2 while ZnCl2, CuCl2 and CoCl2 were ineffective. Hemin, however, did not protect against the alpha, alpha-dipyridyl inhibition of mitochondrial protein synthesis. These results indicate that ferrous iron is required for mitochondrial protein synthesis and suggests that it is through a mechanism independent of hemin concentration.
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216
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Htoo MS, Kofkoff RL, Freedman ML. Erythrocyte parameters in the elderly: an argument against new geriatric normal values. J Am Geriatr Soc 1979; 27:547-51. [PMID: 512282 DOI: 10.1111/j.1532-5415.1979.tb01250.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Erythrocyte parameters in 292 unselected geriatric patients were studied retrospectively. Statistically significant mean decreases compared to the laboratories' normal mean values were found in the red blood cell count (RBC), hemoglobin level, hematocrit, and mean corpuscular hemoglobin concentration; there also was a slight increase in mean corpuscular volume and mean corpuscular hemoglobin. However, when 17 patients with a hemoglobin level less than 10 gm/dl or a hematocrit reading less than 35 percent were excluded, all of the mean values for erythrocyte parameters fell within the normal range. In 71 percent of these 17 patients the etiology of the anemia was documented. Although one cannot definitely exclude a slight change in erythrocyte parameters with aging, it is concluded that the establishment of so-called new geriatric norms is premature, as the population studied included patients with various diseases. Good medical practice dictates continued evaluation and monitoring of patients in whom erythrocyte values are outside the established normal ranges.
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217
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Gruenspecht NR, Torre J, Marcus DL, Freedman ML. Additive inhibition of in vitro rabbit reticulocyte heme and protein synthesis with combinations of isoniazid, chloramphenicol and ethanol. Am J Med Sci 1979; 278:207-15. [PMID: 539598 DOI: 10.1097/00000441-197911000-00004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Isoniazid, chloramphenicol and ethanol are well known hematopoietic toxins. These agents inhibit in vitro rabbit reticulocyte heme synthesis and, as a result, inhibit protein synthesis. When combinations of isoniazid (2 x 10(-3)M) and ethanol (0.1M), isoniazid and chloramphenicol (10(-3)M) or ethanol and chloramphenicol were present in the same incubation, their inhibitory effects on heme and protein synthesis were additive. These results suggest that the development of clinical hematological toxicity in man may result from additive interaction of chemically unrelated compounds which inhibit the heme synthetic pathway.
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218
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Ibrahim NG, Hoffstein ST, Freedman ML. Induction of liver cell haem oxygenase in iron-overloaded rats. Biochem J 1979; 180:257-63. [PMID: 486109 PMCID: PMC1161048 DOI: 10.1042/bj1800257] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Rats were chronically iron-overloaded by intraperitonel injections of iron-dextran. Electron microscopy revealed that the excess iron was deposited in ferritin-like particles packed in lysosomes and scattered in hepatic cytoplasm. No mitochondrial iron deposition or damage was seen. Furthermore, mitochondrial preparations from chronically iron-overloaded animals were found to be contaminated with lysosomes, which could explain previously reported increases in mitochondrial iron by chemical analysis. Mitochondrial function, as measured by cytochromes a-a3, b and c concentrations as well as activity of the rate-limiting enzyme of haem synthesis, delta-aminolaevulinate synthetase, was not diminished by chronic iron-overloading. Microsomal haem was decreased by 30% at the time that haem oxygenase, the rate-limiting enzyme of haem degradation, was increased approx. 3-fold. Animals were given a single intraperitoneal injection of iron-dextran and the activities of delta-aminolaevulinate synthetase and haem oxygenase were measured over 24 h. delta-Aminolaevulinate synthetase activity increased approx. 2-fold in these acutely iron-overloaded rat livers, but at a time after the increase in haem oxygenase. These results suggest that an early consequence of excess iron in liver is acceleration of the rate of haem degradation, possible by haem oxygenase.
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219
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Ibrahim NG, Spieler PJ, Freedman ML. Ethanol inhibition of rabbit reticulocyte haem synthesis at the level of delta-aminolaevulinic acid synthetase. Br J Haematol 1979; 41:235-43. [PMID: 218606 DOI: 10.1111/j.1365-2141.1979.tb05852.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ethanol inhibition of rabbit reticulocyte synthesis occurs as a result of a decrease in haem synthesis. The present study therefore was undertaken in order to localize the inhibitory site of ethanol on the haem biosynthetic pathway. Ethanol (0.05--0.15 M) inhibition of reticulocyte protein synthesis was prevented by simultaneous incubation with 0.025--1 mM delta-aminolaevulinic acid (ALA). Ethanol inhibited both 14C-glycine and 14C-ALA incorporation into haem. However, the extent of haem formation with 14C-ALA as substrate in the presence of ethanol was still equal to that when 14C-glycine was used. These data suggest that ethanol inhibits the haem synthetic pathway at several loci, but that the decrease in haem synthesis, responsible for the decrease in protein synthesis, is due to the inhibition at the rate-limiting enzyme, delta-aminolaevulinic acid synthetase (ALA-S). To confirm this, ALA-S activity was then directly measured in intact reticulocytes, and it was shown that ethanol indeed inhibited its activity. The inhibition of ALA-S was prevented by 10(-4) M dibutyryl cyclic AMP (db cAMP) or theophylline, agents which elevate intracellular cAMP and which have previously been shown to prevent and reverse ethanol inhibition of haem and protein synthesis. Thus, it appears that cAMP protects against ethanol toxicity by preventing inhibition of ALA-S.
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220
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Abstract
An in vitro model consisting of enamel from extracted human molars, suspended from wires in inoculated culture tubes, was used to study the adhesion of bacteria to enamel. Under conditions in which there was no macroscopically visible plaque formation, electron micrographs showed no bacterial deposits on the enamel surface. In samples where Streptococcus mutans attached to enamel, an extracellular, pellicle-like material was associated with the bacteria adjacent to the enamel. This material appeared to bind to the enamel surface and to mediate bacterial attachment. Membrane-filtered (Millipore Corp.) saliva deposited a thin surface layer on the enamel, but there were no observable alterations of S. mutans attachment to enamel pretreated with saliva. It was noted that Bratthall serotype c and e strains of S. mutans, when grown in glucose-containing medium, attached, although less tenaciously, to enamel and nichrome wires. Chemical and gas chromatographic analyses of cell-associated materials formed by serotype c and e strains cultured in glucose-containing medium revealed low amounts of glucose-positive material and no polymer linkages characteristic of glucan; yet the same strains cultured in sucrose-containing medium had relatively high amounts of glucose-positive material, with polymer linkages-characteristic of glucan. Serotype a, b, and d strains could attach only in sucrose-containing media.
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221
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Karpatkin S, Freedman ML. Hypersplenic thrombocytopenia differentiated from increased peripheral destruction by platelet volume. Ann Intern Med 1978; 89:200-3. [PMID: 567025 DOI: 10.7326/0003-4819-89-2-200] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Platelet volume distribution was examined in 16 patients with hepatosplenomegaly and platelet counts of 45 000 to 90 000/mm; 12 patients with autoimmune thrombocytopenia and randomly matched platelet counts; and 20 normal subjects. Five platelet volume variables of increasing platelet size were defined from the averages of 20 normal curves. Patients with hypersplenism had decreased volume values of 78% to 87% (mean, 83%) of the average normal population (P less than 0.001). Patients with autoimmune thrombocytopenic purpura had values significantly greater than normal by 124% to 149% (mean, 134%) (P less than 0.001). Patients with autoimmune thrombocytopenic purpura, when compared with hypersplenic patients, had significantly greater platelet volume values ranging from 154% to 174% (mean, 161%), P less than 0.001. We concluded that patients with hepatosplenomegaly have smaller platelets in their peripheral blood and a platelet volume distribution that can be distinguished easily from patients with autoimmune thrombocytopenic purpura, despite comparable platelet counts.
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222
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Spieler PJ, Ibrahim NG, Freedman ML. Heat inhibition of reticulocyte protein synthesis. Evidence for a mechanism independent of the hemin-controlled repressor. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 518:366-79. [PMID: 656422 DOI: 10.1016/0005-2787(78)90193-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Incubation of rabbit reticulocytes at 45 degrees C results in a prompt but reversible decrease in protein synthesis and a concomitant conversion of polyribosomes to smaller aggregates. These effects occur even in the presence of 100 micrometer hemin in the incubation medium. There is also inhibition of heme synthesis but this occurs at a later time than the effect on protein synthesis. The inhibtion of heme synthesis results from a decrease in activity of beta-aminolevulinic acid synthetase. This decrease of heme synthesis appears to be secondary to the inhibition of protein synthesis with resultant accumulation of intramitochondrial heme (which will decrease beta-aminolevulinic acid synthetase activity). An inhibitor of reticulocyte cell-free protein synthesis formed in the postribosomal supernatants of cells incubated at both 45 and 37 degrees C but not at 0 degrees C. No temporal or quantitative differences in the amount of this inhibitor from cells treated at either 37 or 45 degrees C was apparent. The inhibitor was not found in the fraction where the hemin-controlled repressor is isolated. It is concluded that heat inactivation of intact reticulocyte protein synthesis does not depend upon a decrease in heme synthesis, heme concentration or generation of the hemin-controlled repressor. Furthermore, it appears that the inhibitor formed in the post-ribosomal supernatant cannot be the sole cause of the heat inhibition of protein synthesis.
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223
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Cohen HS, Freedman ML, Goldstein BD. The problem of benzene in our environment: clinical and molecular considerations. Am J Med Sci 1978; 275:124-36. [PMID: 352148 DOI: 10.1097/00000441-197803000-00001] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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224
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Ibrahim NG, Gruenspecht NR, Freedman ML. Hemin feedback inhibition at reticulocyte delta-aminolevulinic acid synthetase and delta-aminolevulinic acid dehydratase. Biochem Biophys Res Commun 1978; 80:722-8. [PMID: 637863 DOI: 10.1016/0006-291x(78)91304-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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225
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Tanzer JM, Freedman ML. Genetic alterations of Streptococcus mutans' virulence. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1978; 107:661-72. [PMID: 33544 DOI: 10.1007/978-1-4684-3369-2_75] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The use of mutants defective in caries-associated traits has enabled the genetic dissociation of agglutination from adhesion, the demonstration of serotype-specific contributions of IPS to virulence, the importance of glucanohydrolase to virulence to a greater degree than to plaque formation, and the apparent lack of importance of agglutination to virulence. We have also been able to demonstrate the ability of plaque formation-defective mutants and other variants both to infect and to emerge, yet not to cause disease. Additional mutants, currently under study in our laboratory include fructanase, invertase, and sucrose permease-defectives. Ultimately, the identification of key, probably surface-associated virulence factors will offer more potent and specific antigens for directed immune responses by the host.
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226
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Freedman ML, Spieler PJ, Rosman J, Wildman JM. Cyclic AMP maintenance of rabbit reticulocyte haem and protein synthesis in the presence of ethanol and benzene. Br J Haematol 1977; 37:179-94. [PMID: 203310 DOI: 10.1111/j.1365-2141.1977.tb06834.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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227
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Reiskin AB, Hummel E, Kirchhof S, Freedman ML. Rare earth imaging in dental radiology. THE JOURNAL OF PREVENTIVE DENTISTRY 1977; 4:7-13. [PMID: 269266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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228
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Freedman ML, Matteson SR. Fine structure of the Panorex image. ORAL SURGERY, ORAL MEDICINE, AND ORAL PATHOLOGY 1977; 43:631-42. [PMID: 265492 DOI: 10.1016/0030-4220(77)90120-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The plane of focus free of blur margin, as well as the rate of increase of blur margin both medial and lateral to the plane of focus, has been described in the Panorex panoramic x-ray machine by means of a continuous phantom. The average of readings made at ninety-eight separate film positions yields a focaltrough thickness of 4.3 mm. if a blur margin of 10 per cent of the phantom's film image is accepted, the percentage blur increasing directly with trough thickness. The factor enlargement of objects at the plane of focus is uniform at 1.25 and increases along with percentage blur more rapidly for objects medial to the plane of focus than for objects lateral to it.
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229
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Freedman ML, Wildman JM, Rosman J, Eisen J, Greenblatt DR. Benzene inhibition of in vitro rabbit reticulocyte haem synthesis at delta aminolaevulinic acid synthetase: reversal of benzene toxicity by pyridoxine. Br J Haematol 1977; 35:49-60. [PMID: 857848 DOI: 10.1111/j.1365-2141.1977.tb00562.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Benzene (0.113 M) inhibited haem and protein synthesis in rabbit reticulocytes. This inhibition of haem synthesis was found when L-2-[14C]-glycine was used as the radioactive precursor. However, when 4-[14C]delta-aminolaevulinic acid (ALA) was used, there was no significant inhibition. Since ALA measures the haem synthetic pathway beyond the enzyme delta-aminolaevulinic acid synthetase (ALA synthetase), these results suggest that benzene inhibits haem synthesis at or before ALA synthetase. This was confirmed by demonstrating that 1 mM ALA both protected against and reversed the benzene inhibition of reticulocyte protein synthesis. In addition, 1 mM pyridoxine both protected against and reversed the benzene inhibition of reticulocyte protein synthesis. In addition, ImM pyridoxine both protected against and reversed the benzene inhibition of reticulocyte haem and protein synthesis. These results indicate that benzene (or a metabolite) either competes with pyridoxal phosphate at ALA synthetase or competes with pyridoxine for pyridoxal phosphokinase. These results are discussed in terms of their implications for the possible roles of ALA synthetase and the haemin-controlled repressor in benzene-induced aplastic anaemia.
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Freedman ML, Cohen HS, Rosman J, Forte FJ. Ferritin and sideroblastic anaemias: inhibition of protein synthesis by protease contaminants in commercial preparations of ferritin. Br J Haematol 1976; 32:579-87. [PMID: 1259940 DOI: 10.1111/j.1365-2141.1976.tb00962.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Commercial preparations of ferritin inhibited reticulocyte-lysate cell-free protein synthesis and disaggregated polyribosomes to monoribosomes and ribosomal subunits. These effects were prevented by addition of reduced glutathione (GSH) to the incubation medium, but ferritin did not lower GSH concentration in the lysates. The more purified the ferritin preparation, the less inhibition of protein synthesis was observed. These data suggested that the effect was due to a contamination of the ferritin with proteolytic activity. In confirmation of this proposal we demonstrated that there was protease activity in both the 2X and 5X crystalized ferritin preparations, with 2.5 times greater activity in the 2X preparation. The proteolytic activity in ferritin was inhibited by incubation with the protease inhibitor tosyl lysine chloromethyl ketone (TLCK). When an amount of trypsin equivalent to the protease activity of the ferritin was added to the incubation mixture, similar effects on protein synthesis and the ribosome-polyribosome component were found. Both GSH and TLCK prevented these effects of trypsin. These data suggest that the previously reported effect of ferritin on reticulocyte cell-free protein synthesis was due to contamination of the ferritin by a protease. It appears that ferritin does not play a direct role in the pathogenesis of sideroblastic anaemias.
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Wildman JM, Freedman ML, Rosman J, Goldstein B. Benzene and lead inhibition of rabbit reticulocyte heme and protein synthesis: evidence for additive toxicity of these two components of commercial gasoline. RESEARCH COMMUNICATIONS IN CHEMICAL PATHOLOGY AND PHARMACOLOGY 1976; 13:473-88. [PMID: 935637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Both benzene and lead are known hematopoietic toxins. These compounds are components of commercial gasoline, and therefore pose an environmental risk. The present study demonstrates that benzene and lead individually inhibit both intact reticulocyte heme and protein synthesis in the presence or absence of iron-transferrin. When these two compounds are present in the same incubation, their effects are additive. These in vitro results suggest that further evaluation of the combined risks of benzene and lead is indicated. Furthermore, the data shows the potential for additive interaction by chemically unrelated environmental compounds.
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Freedman ML, Rosman J. A rabbit reticulocyte model for the role of hemin-controlled repressor in hypochromic anemias. J Clin Invest 1976; 57:594-603. [PMID: 2617 PMCID: PMC436692 DOI: 10.1172/jci108315] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Hemin allows maximal protein synthesis in intact rabbit reticulocytes and their cell-free lysate preparations by retarding the formation of a translational repressor (HCR) found in the postribosomal supernate. In order to evaluate the role of HCR in the pathogenesis of hypochromic anemias, HCR was isolated and partially purified from intact rabbit reticulocytes incubated in vitro with either 0.1 mM alpha,alpha-dipyridyl (an iron-chelating agent) or 0.1 M ethanol. Both of these agents inhibit reticulocyte protein synthesis. Hemin (50 muM) protects against the inhibition by both agents. A ferrous iron-transferrin mixture, however, protects only against alpha,alpha-dipyridyl. Both alpha,alpha-dipyridyl and ethanol inhibit heme synthesis before the time that protein synthesis is affected, while neither lowers either ATP or GSH levels. These results indicate that while both agents inhibit heme synthesis, alpha,alpha-dipyridyl does so by inducing iron deficiency while ethanol works at a non-iron-requiring step. When HCR was isolated from intact cells and assayed in the reticulocyte cell-free systems, plus and minus hemin, premature appearance of HCR was found in cells incubated in vitro with alpha,alpha-dipyridyl or ethanol. When hemin was present in the intact cell incubation, the appearance of HCR was retarded. The HCR from alpha,alpha-dipyridyl ethanol-treated cells was partially purified and eluted at the same location on a Sephadex G-200 column (molecular weight approximately 3 x 10(5)) as that from postribosomal supernates incubated minus hemin. In addition rabbits with phenylhydrazine-induced hemolytic anemia were given intravenous ethanol in vivo at a dose of 0.4 ml/kg. This concentration of alcohol resulted in an inhibition of the rate of heme synthesis and protein synthesis as well as an acceleration of HCR formation in reticulocytes. The HCR from these in vivo treated rabbits was isolated, partially purified, and assayed in an identical fashion as the in vitro experiments. These in vivo experiments further support the physiological and pathophysiological role of HCR in reticulocytes. On the basis of these results a model for a role of HCR in some of the hypochromic anemias is proposed. In iron deficiency or chronic disease (where iron is not available to the erythroblast for heme synthesis) HCR appears prematurely and inhibits protein synthesis. When heme synthesis is inhibited by ethanol but there is sufficient intracellular iron, HCR appears prematurely and inhibits protein synthesis, iron accumulates in the erythroblast, and the end result is sideroblastic anemia.
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Forte FJ, Cohen HS, Rosman J, Freedman ML. Hemin reversal of benzene-induced inhibition of reticulocyte protein synthesis. Blood 1976; 47:145-54. [PMID: 1244909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Benzene (0.056-0.113 M) rapidly and reversibly inhibited protein synthesis in anucleate human sickle cell and rabbit reticulocytes. Hemin (50 muM) both prevented and reversed this effect of benzene. The inhibition in rabbit reticulocytes was accompanied by a conversion of polyribosomal disaggregation required ribosomal movement along mRNA and was also prevented and reversed by 50 muM hemin. Benzene was also shown to inhibit heme synthesis in rabbit reticulocytes while neither ATP nor GSH levels were altered. A translational repressor (HCR) of reticulocyte cell-free protein synthesis was isolated from intact cells incubated with benzene, while no significant amount of HCR was found in cells incubated with both benzene and hemin. These results indicated that benzene inhibits translation at the heme-dependent site of initiation. The clinical implications of these experiments remain to be elucidated.
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234
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Freedman ML, Matteson SR. A collimator for reduced radiation dose with improved visualization of soft tissues. Radiology 1976; 118:226-8. [PMID: 1244661 DOI: 10.1148/118.1.226] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The authors describe a collimator for use in diagnostic radiology. Clinical radiographs show enhanced soft-tissue detail through the use of interchangeable straight and curved wedge filters, and in situ dosimetry using a head phantom shows that the provision for asymmetric beam limitation results in reduction of absorbed dose.
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235
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Freedman ML, Forte FJ, Roseman J. Comparison of the effects of carbamyl phosphate and sodium cyanate on protein synthesis and glutathione concentration in human sickle cell and rabbit reticulocytes. J Pharmacol Exp Ther 1975; 195:340-6. [PMID: 1185603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Two carbamylating agents, carbamyl phosphate and sodium cyanate, are currently being evaluated as therapeutic drugs for the treatment of sickle cell anemia. Since the clinical usefulness of these drugs might be limited by toxicity, a comparative in vitro study of the relative inhibition of human sickle cell and rabbit reticulocyte protein synthesis was performed. Sodium cyanate was found to inhibit human sickle cell protein synthesis at concentrations one-eighth that of carbamyl phosphate. Carbamyl phosphate lowered reduced glutathione levels to a similar degree as sodium cyanate and was slightly more effective as an in vitro antisickling agent, which is evidence that carbamyl phosphate enters these cells. When rabbit reticulocyte protein synthesis was investigated, carbamyl phosphate was found to be noninhibitory at concentrations as high as 128 mol/mol of hemoglobin in the incubation medium, while cyanate was inhibitory at much lower concentrations. The effect of carbamyl phosphate on glutathione concentrations, however, was virtually identical to that of cyanate. These results show that the effect on protein synthesis does not result from the lowered glutathione levels. It is concluded that both the therapeutic and toxic effects of sodium cre, there might be differences in toxicity between animals and humans.
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Freedman ML, Karpatkin S. Heterogeneity of rabbit platelets. V. Preferential splenic sequestration of megathrombocytes. Br J Haematol 1975; 31:255-62. [PMID: 1201241 DOI: 10.1111/j.1365-2141.1975.tb00855.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Rabbits were either splenectomized or subjected to splenic blockade with phenylhydrazine in order to determine the splenic platelet and megathrombocyte (large-platelet) pools. The average splenic platelet pool calculated from both methods was 35% of total platelets. The average splenic megathrombocyte pool was 54% of total megathrombocytes. Adrenaline injection into rabbits or dogs revealed a rapid increase in both platelet count and megathrombocyte number which peaked at 2-6 min and returned toward normal in 5-10 min. The platelet volume distribution curve was shifted to the right, indicating the release of large platelets (megathrombocytes) into the circulation. The peak rise in megathrombocyte number was significantly greater than the peak rise in platelet count. Rabbits subjected to splenic massage shifted their platelet volume distribution curve to the right in the absence of a rise in platelet count. It is concluded that the spleen preferentially sequesters megathrombocytes.
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237
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Freedman ML, Karpatkin S. Elevated platelet count and megathrombocyte number in sickle cell anemia. Blood 1975; 46:579-82. [PMID: 1174691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Eight adult patients with sickle cell anemia were followed over a 6-mo period. During this time all patients had elevated plateletcounts, 1.7-fold (mean, 438,398 +/- 86,223), and megathrombocyte numbers, 2.3-fold (mean, 79,535 +/- 38,907), during asymptomatic periods. These data are interpreted as suggesting that the elevated platelets and megathrombocytes in asymptomatic sickle cell patients result from lack of splenic sequestration. During three crises in two patients, both megathrombocyte number and platelet count fell significantly. It is speculated that platelets may be associated with the pathology in this disease. Platelet function studies performed during crises, therefore, must take into account the number of megathrombocytes.
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238
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Freedman ML, Coykendall AL. Variation in internal polysaccharide synthesis among Streptococcus mutans strains. Infect Immun 1975; 12:475-9. [PMID: 240778 PMCID: PMC415311 DOI: 10.1128/iai.12.3.475-479.1975] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Five strains, representative of Streptococcus mutans genetic group III antigenic group d, synthesized and degraded less intracellular polysaccharide (IPS) then 17 strains representative of other S. mutans groups. The strains that synthesize IPS degraded it rapidly. The production of acid in titratable amounts from endogenous IPS was usually complete within 1 h. IPS synthesis in S. mutans increased abruptly at culture glucose concentrations between 0.2 and 0.5% and was quantitated as both iodine-and glucose oxidase-positive material in cell hyrolysates. IPS degradation was measured by acid production in a pH-stat maintained at 7. The existence within group III d of a strain recently shown to be cariogenic in experimental animals suggest that IPS may not be a prerequisite for virulence in these cariogenic bacteria.
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Freedman ML, Cohen HS, Rosman J, Forte FJ. Ethanol inhibition of reticulocyte protein synthesis: the role of haem. Br J Haematol 1975; 30:351-63. [PMID: 1201218 DOI: 10.1111/j.1365-2141.1975.tb00551.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ethanol, in concentrations of 0.05-0.8 M, inhibited intact human and rabbit reticulocyte protein synthesis in the presence of iron-transferrin for endogenous haem synthesis. Associated with this effect there was a conversion of polyribosomes to monoribosomes and a decreased incorporation of radioactive leucine into nascent globin chains. When physiological levels of ethanol (0.05-0.1 M) were used, these effects were prevented by incubation with 50 muM haemin and reversed by removing the alcohol and reincubating with iron-transferrin or haemin. The polyribosomal disaggregation was also prevented by stopping ribosomal movement with 5 mM cycloheximide. Neither ATP nor GSH levels were altered in the presence of ethanol. When non-physiological levels of 0.8 M ethanol were used, haemin did not prevent the inhibition of protein synthesis. Likewise, in the rabbit reticulocyte cell-free lysate system containing haemin inhibition was noted at concentrations greater than 0.05 M ethanol. The polyribosomal disaggregation in reticulocytes incubated with 0.8 M ethanol was associated with decreased dissociation of monoribosomes into subunits. Similarly, when ribosomes were directly suspended cell-free in 0.1 or 0.8 M ethanol there was a decreased percentage of subunits. These results indicate that physiological concentrations of ethanol inhibit initiation of reticulocyte protein synthesis secondary to a block in haem synthesis. When intact cells are exposed to high non-physiological concentrations of ethanol the inhibition is secondary to decreased ribosomal dissociation. The cell-free lysate inhibition is also through this effect on ribosomal dissociation. This study supports the view that alcohol is a direct toxin to developing red cell precursors via its effect on mitochondrial haem synthesis. The physiological role of the decreased dissociation of monoribosomes into subunits is not yet clear.
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Freedman ML, Geraghty M, Rosman J. Hemin control of globin synthesis. Isolation of a hemin-reversible translational repressor from human mature erythrocytes. J Biol Chem 1974; 249:7290-4. [PMID: 4436311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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241
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Nalbandian J, Freedman ML, Tanzer JM, Lovelace SM. Ultrastructure of Mutants of
Streptococcus mutans
with Reference to Agglutination, Adhesion, and Extracellular Polysaccharide. Infect Immun 1974; 10:1170-9. [PMID: 16558106 PMCID: PMC423078 DOI: 10.1128/iai.10.5.1170-1179.1974] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An electron microscopic study of
S. mutans
6715-13 wild type and representatives of three distinct classes of glucan synthesis-defective mutants (which fail to form adherent microbial plaques but agglutinate normally in the presence of exogenous glucans) disclosed the presence of two sucrose-dependent, glucanase-sensitive, extracellular components. In the wild type, these extracellular glucans had predominantly fibrillar (with some globular) morphologies. However, in the mutant strains, there was a consistent reduction in or loss of the fibrillar components and dramatic increases in globular forms. A cell surface-associated fuzzy coat was consistently seen, and it was neither sucrose-dependent nor glucanase-sensitive. The data indicated that in vitro and in vivo adhesion and virulence at smooth tooth surfaces (all these properties dramatically reduced in the mutants) were causally and functionally related to the extracellular, fibrillar, glucan component, whereas in vitro glucan-mediated agglutination may be related to the cell-associated surface fuzzy coat.
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Freedman ML, Tanzer JM. Dissociation of plaque formation from glucan-induced agglutination in mutants of Streptococcus mutans. Infect Immun 1974; 10:189-96. [PMID: 4601768 PMCID: PMC414976 DOI: 10.1128/iai.10.1.189-196.1974] [Citation(s) in RCA: 96] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The traits adhesion and cohesion are manifested in Streptococcus mutans by in vitro plaque formation and glucan-mediated agglutination and have been dissociated in mutants of this caries-associated microbe. In these mutants, which differ from each other in colonial morphology, we have observed a consistent loss of ability to form adhesive microbial deposits (plaque) on wires, but only a minimal alteration from the wild type in ability to agglutinate into macroscopic clumps in the presence of exogenous glucans or sucrose. Also, when these mutants were cultured in sucrose-containing medium, there was an increase in the synthesis of water-soluble, extracellular glucans and a decrease in the synthesis of alkali-soluble, cell-associated glucans. Based on these findings, it appears (i) that in vitro plaque formation and agglutination are distinct and dissociable traits, and (ii) that adhesion but not agglutination appears related to the synthesis of alkali-soluble, cell-associated glucans.
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Tanzer JM, Freedman ML, Fitzgerald RJ, Larson RH. Diminished virulence of glucan synthesis-defective mutants of Streptococcus mutans. Infect Immun 1974; 10:197-203. [PMID: 4842127 PMCID: PMC414977 DOI: 10.1128/iai.10.1.197-203.1974] [Citation(s) in RCA: 148] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The virulence of cell surface-associated, glucan synthesis-defective mutants of Streptococcus mutans strain 6715-13 was studied. Representatives from three groups of such mutants were tested for their pathogenicity in conventionalized, specific pathogen-free rats and gnotobiotic rats. The mutants differ from the wild-type strain in that each failed to form plaque on the smooth surfaces of the teeth and to cause smooth surface caries. Although the ability to form cell surface-associated glucans was not a strict requirement for the expression of virulence in the sulci of the teeth, it augmented virulence at such sites. However, the ability to form cell surface-associated glucans and to adhere to the teeth was clearly not the sole determinant of virulence.
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Freedman ML, Schiffman FJ, Geraghty M. Studies on the mechanism of cyanate inhibition of reticulocyte protein synthesis. Br J Haematol 1974; 27:303-12. [PMID: 4846277 DOI: 10.1111/j.1365-2141.1974.tb06797.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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246
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247
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Freedman ML, Friedberg D, Mucha J, Troll W. Tosyl lysine chloromethyl ketone inhibition of the initiation of hemoglobin synthesis. Biochem Pharmacol 1973; 22:2441-51. [PMID: 4745640 DOI: 10.1016/0006-2952(73)90347-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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248
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249
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Brown F, Freedman ML, Troll W. Sensitive fluorescent determination of trypsin-like proteases. Biochem Biophys Res Commun 1973; 53:75-81. [PMID: 4795362 DOI: 10.1016/0006-291x(73)91403-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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250
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Freedman ML. New drugs in the treatment of sickle cell anemia. Am J Med Sci 1973; 265:371-3. [PMID: 4576757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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