Additional cochinmicins from a Microbispora sp.
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Bacteria↗
Biomedical subjects
D L Williams
Publications and source records attributed to D L Williams.
A sequential multi-assay protocol for the preclinical assessment of natural product complex carbohydrate immunomodulators.
A major barrier to the understanding, development and utilization of natural product complex carbohydrate immunomodulators has been the lack of standardization during pre-clinical efficacy and safety testing. In addition, it has been our experience that no single assay system or model is adequate for assessing preclinical efficacy and safety of these agents. To address these important issues, our laboratory group has developed a sequential multi-assay protocol for the preclinical evaluation of natural product complex carbohydrate immunomodulators. This sequential multi-assay screening protocol is divided into four phases: 1) physiochemical characterization of the carbohydrate polymer; 2) evaluation of immune stimulatory activity; 3) assessing in vivo anti-microbial activity and anti-tumor efficacy and 4) preclinical safety evaluation. This sequential protocol provides an effective, reproducible and rational approach to the preclinical assessment of complex carbohydrate immunomodulators that, in our experience, is predictive of clinical safety and efficacy.
Adjuvants, Immunologic↗
Trisomy 21 as the sole acquired chromosomal abnormality in children with acute lymphoblastic leukemia.
Most studies of cytogenetic abnormalities in leukemia patients have focused on structural chromosomal rearrangements. Less attention has been paid to the role of single numerical abnormalities in the complex mechanisms of leukemia pathogenesis. We therefore studied 11 cases of acute lymphoblastic leukemia (ALL) with trisomy 21 as the sole chromosomal abnormality, representing 1.8% of 601 completely banded cases of ALL seen during a 10-year period. Bone marrow cells from all but one of these cases also had normal karyotypes, representing 8 to 77% of the completely analyzed metaphases. Each of the five cases tested lacked evidence of trisomy 21 mosaicism of constitutional origin in peripheral blood samples. The presenting features of these five girls and six boys were heterogeneous but tended to reflect lower-risk ALL: median age, 3.3 years (range 1-18 years), median leukocyte count, 11.6 x 10(9)/l (range 1.8-82 x 10(9)/l), white race, and a B-cell precursor immunophenotype. Complete remissions were readily induced in all 11 patients. With follow-up ranging from 1+ months to 6.4+ years, the only relapses have been extramedullary (testis and central nervous system) in two patients, both of whom have since achieved second remissions of greater than 76 and greater than 65 months. Trisomy 21 as the sole chromosomal abnormality in childhood ALL appears related to favorable presenting risk features and may represent a good prognosis subset within the group of patients with 47-50 chromosomes.
Adolescent↗
Impact of three methods of treatment intensification on acute lymphoblastic leukemia in children: long-term results of St Jude total therapy study X.
Long-term follow-up observations are reported on 427 patients who received one of three different intensified therapies in total therapy study X for acute lymphoblastic leukemia (ALL). In the trial for 'standard-risk' ALL, 154 of 309 patients in complete remission were randomized to receive high-dose methotrexate (HDMTX, 1 g/m2) periodically during the first 72 of 120 weeks of standard continuation therapy with 6-mercaptopurine and oral MTX; the remaining 155 patients received 1800 cGy cranial irradiation and intrathecal MTX, followed by 6-mercaptopurine/MTX therapy interrupted from week 36-71 for substitution of two other pairs of drugs. At 9 years of follow-up, significantly higher proportions of patients in the HDMTX group have maintained complete remissions (64 +/- 7%, SE, vs. 52 +/- 6%, p = 0.03), hematologic remissions (73 +/- 6% vs. 62 +/- 6%, p = 0.03), and testicular remissions (94 +/- 5% vs. 80 +/- 8%, p = 0.03); however, the proportion continuing in central nervous system remission has been lower (84 +/- 5% vs 93 +/- 4%, p = 0.02). In the evaluation of teniposide/cytarabine and delayed cranial irradiation for 'high-risk' ALL, 36 +/- 9% of 101 patients are predicted to be event-free survivors at 9 years. Altogether, 217 (51%) of the 427 patients are event-free survivors after at least 7 years of follow-up (median, 9 years); an additional 75 patients are alive and free of leukemia for a median of 6.4 years after successful remission retrieval therapy, boosting the total number of long-term survivors to 292 (68%). These results establish the efficacy of HDMTX for patients with standard-risk ALL and indicate the potential of teniposide/cytarabine for use in multiagent regimens for patients with high-risk disease. The overall survival figure, 68%, affords a benchmark for other studies assessing long-term outcome in ALL.
Child↗
Suppression of cAMP-mediated signal transduction in mouse adrenocortical cells which express apolipoprotein E.
We have reported previously that expression of the human apolipoprotein E (apoE) gene in mouse Y1 adrenocortical cells suppresses basal and adrenocorticotropin (ACTH)-stimulated steroidogenesis. To understand the mechanism of this suppression, we have examined the integrity of cAMP regulated events required for adrenal steroidogenesis. Both acute and chronic responses to ACTH or cAMP are suppressed in Y1 cells which express apoE (Y1-E cells) as compared with parental Y1 cells. Acute morphologic changes in response to cAMP and acute induction of steroidogenesis by cAMP are suppressed in the Y1-E cell lines. Constitutive expression of P450-cholesterol side chain cleavage enzyme mRNA, the rate-limiting enzyme in steroid hormone synthesis, is reduced up to 11-fold in the Y1-E cell lines. The level of mRNA encoding P450-cholesterol side chain cleavage correlates directly with the reduction in basal steroid production observed in the individual Y1-E cell lines. Expression of P450-11 beta-hydroxylase mRNA, although readily detectable in Y1 parent cells, is absent or reduced in the Y1-E cell lines. Inhibition of cAMP-regulated gene expression is not restricted to genes required for steroid synthesis, since cAMP induction of ornithine decarboxylase mRNA is also inhibited in the Y1-E cell lines. These data indicate that suppression of steroidogenesis in Y1-E cells is due, at least in part, to inhibition of cAMP-regulated gene expression. These effects are not due to a defective cAMP-dependent protein kinase, since kinase activity in vitro and activation in vivo are unaltered in the Y1-E cell lines. These results suggest that expression of apoE in Y1 cells blocks cAMP-mediated signal transduction at a point distal to activation of cAMP-dependent protein kinase.
Adrenal Cortex↗
Identification of high affinity endothelin-1 receptor subtypes in human tissues.
Two subtypes of the high affinity endothelin-1 (ET-1) receptor were identified in human tissue, and were distinguished by their differential affinities for sarafotoxin S6c (S6c). Uterus contains mostly the ETA subtype, with low affinity for S6c (Ki greater than 7300 nM), while the predominant subtype in hippocampus is ETB, with high affinity for S6c (Ki = 0.25 nM). These subtypes also have different affinities for [Ala1,3,11,15]-ET-1, which was found to be ETB selective. The two subtypes distinguished by these ligands in human tissue correspond to the subtypes previously identified in rat. Differential stimulation of phosphatidyl inositol turnover in rat tissue slices by ET-1 and S6c indicates that both ETA and ETB subtypes represent functional receptors.
Animals↗
A method for the solubilization of a (1----3)-beta-D-glucan isolated from Saccharomyces cerevisiae.
This report describes a method for the solubilization of a micro-particulate beta-D-glucan. Insoluble glucan is dissolved in methyl sulfoxide and urea (8M) and partially phosphorylated at 100 degrees. The resulting water-soluble product is called glucan phosphate. The conversion rate is 70%, and the preparation is endotoxin free as determined by the Limulus lysate procedure. Glucan phosphate is composed of 34.66% C, 6.29% H, 42.83% O, and 2.23% P and has a repeating-unit empirical formula of (C6H10O5)7.PO3H2, indicating a phosphate group substitution on every seventh glucose subunit. Molecular-weight averages, polydispersity, and intrinsic viscosity were determined by aqueous high-performance size-exclusion chromatography (s.e.c.) with on-line, multi-angle laser light scattering (m.a.l.l.s.) photometry and differential viscometry (d.v.). Two polymer peaks were resolved. Peak 1 (Mw = 3.57 x 10(6) daltons), represents approximately 2% of the total polymers, while peak 2 (Mw = 1.10 x 10(5) daltons) comprises approximately 98% of polymers. 13C- and 31P-n.m.r. spectroscopy confirmed the beta-1,3 interchain linkage and the presence of a phosphate group. In solution, glucan phosphate polymers self-associate in a triple-helical arrangement. The ability to prepare a immunologically active, non-toxic, water-soluble beta-D-glucan preparation will greatly enhance the clinical utility of this class of compounds.
Drug Compounding↗
New recurring chromosomal translocations in childhood acute lymphoblastic leukemia.
We identified seven new recurring translocations among 483 cases of acute lymphoblastic leukemia (ALL) with adequate chromosome banding studies. Four were apparently balanced [t(1;3)(p34;p21), t(7;9)(p15;p23-p24), t(12;13)(p13;q14), t(17;19)(q22;p13)], while three were unbalanced with the formation of a dicentric chromosome [dic(7;9)(p13;p11), dic(7;12)(p11;p12), and dic(12;17)(p11;p11-p12)]. One translocation was observed in five cases, two in four cases, and the remaining four in two cases each. The modal chromosome numbers in these 21 cases were 45 (n = 11), 46 (n = 8), and 47 (n = 2). Eight of the 11 cases with a dicentric chromosome had a modal number of 45. Only a single translocation was found in 14 cases (67%), representing the sole structural abnormality in six cases. In three of the seven translocation subgroups, the blast cells were consistently of B lineage (pre-B, early pre-B, or both); in all others, they represented both the B and T lineages. The small size of these subgroups prevented definitive clinical correlations, although it may be important that two of the four cases with a t(17;19) and an early pre-B-cell immunophenotype had disseminated intravascular coagulation, an event usually observed in acute promyelocytic leukemia or T-cell ALL. These findings add substantially to the existing list of nonrandom chromosomal translocations in childhood ALL and may help to explain the genetic alterations leading to the loss of normal growth control mechanisms in this disease.
Adolescent↗
The bovine endothelin receptor has an apparent molecular weight of 43,000.
In crosslinking experiments, [125I]endothelin-1 was treated with N-hydroxysuccinimidyl-4-azidobenzoate, purified by HPLC, allowed to bind to bovine aortic membranes and then photoactivated. Autoradiography of sodium dodecyl sulfate polyacrylamide gel electrophoretograms of the products of this reaction showed that a component of apparent Mr = 42,000 was specifically labelled by endothelin-1 under reducing conditions. Under nonreducing conditions, a small amount of 125I-labelled endothelin-1 specifically labelled a component of apparent Mr = 45,900 in the absence of crosslinking agent. Non-radiolabelled endothelin analogues with a wide range of binding affinities inhibited specific labelling of the Mr = 42,000 and 45,900 components in parallel over the concentration ranges which inhibited binding of radiolabelled endothelin. Specific labelling of these components was also observed in parallel in membranes from bovine heart and kidney. The components labelled in the presence and absence of crosslinker appear to be the same, and the small difference in apparent Mr in the labelled components is likely due to a difference in conformational constraints arising from the two labelling processes, with a true, corrected Mr of 43,400. Since the specific labelling of this component is related to physiologically relevant binding in several bovine tissues, we conclude that it is a component of the bovine endothelin receptor.
Affinity Labels↗
Sarafotoxin S6c: an agonist which distinguishes between endothelin receptor subtypes.
In contrast to endothelin-1 (ET-1) and several of its analogues, sarafotoxin S6c (S6c) was a much more potent inhibitor of [125I]-ET-1 binding in rat hippocampus and cerebellum (Ki approximately 20 pM) than in rat atria and aorta (Ki approximately 4500 nM), suggesting the existence of ET-1 receptor subtypes (aorta/atria, ETA; hippocampus/cerebellum, ETB). S6c was a potent activator of PI turnover in hippocampus (EC50 approximately 10 nM) but not atria (EC50 greater than 1 microM), unlike ET-1 which was active in both tissues. S6c, therefore, is a highly selective ETB agonist. Furthermore, S6c was a potent pressor agent in the pithed rat (ED25 mm Hg approximately 0.1 nmoles/kg, i.v.), suggesting that the ETB receptor subtype may be important in cardiovascular function.
Animals↗
Expression of the human apolipoprotein E gene suppresses steroidogenesis in mouse Y1 adrenal cells.
The lipid transport protein, apolipoprotein E (apoE), is expressed in many peripheral tissues in vivo including the adrenal gland and testes. To investigate the role of apoE in adrenal cholesterol homeostasis, we have expressed a human apoE genomic clone in the Y1 mouse adrenocortical cell line. Y1 cells do not express endogenous apoE mRNA or protein. Expression of apoE in Y1 cells resulted in a dramatic decrease in basal steroidogenesis; secretion of fluorogenic steroid was reduced 7- to greater than 100-fold relative to Y1 parent cells. Addition of 5-cholesten-3 beta,25-diol failed to overcome the suppression of steroidogenesis in these cells. Cholesterol esterification under basal conditions, as measured by the production of cholesteryl [14C]oleate, was similar in the Y1 parent and the apoE-transfected cell lines. Upon incubation with adrenocorticotropin or dibutyryl cAMP, production of cholesteryl [14C]oleate decreased 5-fold in the Y1 parent cells but was unchanged in the apoE-transfected cell lines. These results suggest that apoE may be an important modulator of cholesterol utilization and steroidogenesis in adrenal cells.
Adrenal Glands↗
Improved outcome in childhood acute lymphoblastic leukaemia with reinforced early treatment and rotational combination chemotherapy.
To improve outcome in childhood acute lymphoblastic leukaemia (ALL), a stratified, randomised study of extended intensified chemotherapy was done. 358 evaluable patients received remission reinforcement therapy (teniposide, cytarabine, high-dose methotrexate) added to a four-drug induction regimen. Those achieving complete remission were randomised on the basis of risk group assignment to conventional continuation treatment or to four pairs of drugs rotated weekly or every 6 weeks. All patients received intrathecal chemotherapy; higher-risk patients also received 1800 cGy cranial irradiation after 1 year of remission. Complete remission was induced in 96% of the patients. At median follow-up of 40 (range 19-73) months, 4-year event-free survival (SE) was 73 (4)% overall, 81 (6)% in the lower-risk group (n = 110), and 69 (5)% in the higher-risk group (n = 248). Outcome within risk groups was not significantly affected by the speed of rotation of drug pairs during continuation treatment. Various high-risk subgroups had apparently improved responses to this treatment. This intensified chemotherapy may cure 69-77% of children with ALL.
Actuarial Analysis↗
Proteoglycan-collagen interactions in chronic superficial keratitis in the dog.
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Animals↗
Macrophages from nephrotic rats regulate apolipoprotein E biosynthesis and cholesterol content independently.
The effects of the nephrotic syndrome in rats on the cholesterol content and the biosynthesis of apolipoprotein E (apoE) by resident peritoneal macrophages have been investigated. Since the nephrotic syndrome has been associated with an increased risk of coronary atherosclerosis, we hypothesized that macrophages from nephrotic rats would accumulate cholesterol and undergo transformation into foam cells, with a concomitant increase in apoE biosynthesis. The nephrotic syndrome was induced in rats with puromycin aminonucleoside. Peritoneal macrophages exposed in vivo for 7-21 d to ascites fluid derived from plasma containing sixfold elevations of lipoproteins did not accumulate unesterified or esterified cholesterol. Nevertheless, immunoprecipitation assays after incubation of the isolated cells with [35S]methionine, or immunoblot analysis of the incubation medium demonstrated a 2.6-fold increase in apoE secretion compared with normal macrophages. This increase was accompanied by 5- to 10-fold increases in cellular apoE messenger RNA as determined by quantitative solution hybridization assay. Peritoneal macrophages cultured from nephrotic rats during the period of hypercholesterolemia also showed distinct and highly reproducible morphologic changes. The dissociation between apoE biosynthesis and macrophage cholesterol content provides new insight into the response of peritoneal macrophages in vivo to endogenous hyperlipemia.
Animals↗
Comparison of polymerase chain reaction technique with other methods for detection of Mycobacterium leprae in tissues of wild nine-banded armadillos.
Thirty, nine-banded armadillos weighing between 3 and 5 kilograms trapped from an area endemic for armadillo leprosy were collected at random; killed, autopsied and examined histopathologically. Also, one of the right inguinal lymph nodes was removed under sterile precautions and examined using PCR, direct smear examination, mouse footpad study, culture in laboratory media and histopathology with a view to detecting Mycobacterium leprae. Blood was collected at death and tested for IgM antibodies to PGL-1. According to the PCR study of the inguinal lymph nodes 16 of 30 armadillos (53.3%) had evidence of M. leprae. Significant levels of IgM antibodies to PGL-1 and identifiable lepromatous granuloma in inguinal lymph nodes were found in 2 animals (6.7%) with advanced disseminated disease. The prevalence of generalized leprosy according to autopsy study was 13.3% and according to histopathological examination of ear tissue 3.3%. The presence of M. leprae in the tissues evoked no special tissue reaction in the early stages. The pattern of spread of the disease in 2 animals closely resembled that found in experimental animals infected intracutaneously. Initiation of infection by inoculation of M. leprae through thorn pricks remains a distinct possibility.
Animals↗
Relationship between apolipoprotein E mRNA expression and tissue cholesterol content in rat adrenal gland.
Among extrahepatic tissues the adrenal gland has one of the highest concentrations of apoE mRNA and the highest rate of apoE synthesis. In the present investigation several previously described in vivo treatments were used to assess the relationship between apoE expression and cellular cholesterol in the rat adrenal gland. Treatment of rats with 4-aminopyrazolo[3,4-d]pyrimidine (4-APP) to lower serum cholesterol concentration and deplete adrenal gland cholesterol content decreased adrenal gland apoE mRNA concentration. These adrenal responses were blocked by dexamethasone (DEX) suggesting that the effect of 4-APP occurred indirectly via stimulation of the adrenal gland by endogenous adrenocorticotrophic (ACTH). Relative to control rats, DEX treatment increased both adrenal gland cholesterol content and apoE mRNA concentration. Concurrent ACTH and DEX administration reduced both adrenal gland cholesterol content and apoE mRNA concentration relative to DEX-treated rats. ACTH administration also rapidly decreased adrenal gland apoE mRNA concentration and cholesterol content in rats pretreated with DEX. In all the above experiments, adrenal gland cholesterol content and apoE mRNA concentration were positively correlated (r = 0.78, P = 0.0001). In contrast, aminoglutethimide treatment, which blocks adrenal gland steroidogenesis and greatly increases adrenal gland cholesterol content, was without effect on apoE mRNA concentration. ACTH administration to rats treated with DEX + aminoglutethimide resulted in decreased adrenal apoE mRNA despite greatly increased adrenal cholesterol content. This uncoupling of adrenal gland cholesterol content and apoE mRNA concentration suggests that apoE mRNA expression and cellular cholesterol are regulated independently by ACTH.
Adrenal Glands↗
Isolation, physicochemical characterization and preclinical efficacy evaluation of soluble scleroglucan.
Herein we describe the isolation, physicochemical characterization and preclinical evaluation of a water-soluble biologic response modifier extracted from Sclerotium glucanicum. Alkaline extraction of insoluble S. glucanicum exopolymers produced a soluble scleroglucan composed of a triple-helical beta-1,3-linked glucopyranose backbone with single beta-1,6-linked glucopyranosyl branches every third subunit. Scleroglucan has a weight average molecular mass of 1.56 x 10(6) Da, a weight average root mean square distance from the center of gravity of the molecule to its farthest elements of 51.8 nm, a polydispersity (weight-average molecular mass/number average molecular mass) of 1.83 and intrinsic viscosity of 3.081 dl/g. Scleroglucan (250 mg/kg, intravenously) stimulated in vivo murine macrophage phagocytic activity (66%, P less than .001) and increased in vitro macrophage tumor cytotoxicity against syngeneic tumor targets by 124% (P less than .05). Scleroglucan enhanced (P less than .001) murine bone marrow proliferation in a biphasic manner by up to 328%. Scleroglucan therapy increased survival of mice challenged with syngeneic lymphoma, melanoma or adenocarcinoma. AKR/J mice bearing syngeneic lymphoma (1 x 10(3) cells, intraperitoneally) demonstrated increased (P less than .001) long-term survival (100% vs. 0%, greater than 64 days). C57Bl/6J mice bearing syngeneic melanoma B16 (5 x 10(5) cells, subcutaneously) demonstrated increased long-term survival (64% vs. 0%, P less than .05). C57Bl/6J mice bearing syngeneic adenocarcinoma BW10232 (1 x 10(5) cells, subcutaneously) demonstrated increased (P less than .05) median survival time. In addition, scleroglucan prophylaxis increased resistance of mice to challenge with Staphylococcus aureus, Candida albicans and mouse hepatitis virus A-59. Scleroglucan did not induce toxicity or hepatomegaly. We conclude that: 1) a branched, water-soluble beta-1,3-linked scleroglucan biologic response modifier can be extracted from S. glucanicum; 2) scleroglucan will stimulate immunity, modify experimental neoplastic disease and increase resistance to microbial challenge; and 3) scleroglucan shows promise as an immunopotentiating drug.
Animals↗
Polymerase chain reaction and leprosy.
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DNA, Bacterial↗