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L E Williams

Publications and source records attributed to L E Williams.

At least 19 recordsLinked to original sources
PubMed2001

Heterocycle-based MMP inhibitors with P2' substituents.

Potent and selective inhibition of matrix metalloproteinases was demonstrated for a series of sulfonamide-based hydroxamic acids. The design of the heterocyclic sulfonamides incorporates a six- or seven-member central ring with a P2' substituent that can be modified. Binding interactions of this substituent at the S2' site are believed to contribute to high inhibitory potency against stromelysin, collagenase-3 and gelatinases A and B, and to provide selectivity against collagenase-1 and matrilysin. An X-ray structure of a stromelysin inhibitor complex was obtained to provide insights into the SAR and selectivity trends observed for the series.

Collagenases↗
PubMed2001

Accumulation of radiolabeled anti-CEA antibody (mT84.66) in the case of multiple LS174T tumors in a nude mouse model.

A comparison was made between labeled antibody accumulations in nude mice having either single or multiple human xenografts. The LS174T tumors were implanted subcutaneously. All animals were given 2 micrograms of labeled murine anti-carcinoembryonic antigen (CEA) monoclonal antibody 111In-mT84.66. Some animals were also given specific antibody pretreatment (SAP) of 200 micrograms of unlabeled mT84.66 to reduce liver accumulation of activity. In order to represent these multiple tumor examples, a simple initial-phase pharmacokinetic model was first fitted to each of the two groups (SAP and PBS treated) of single-tumor animals. Using the resultant six non-adjustable parameters as constants, the n = 1 uptake model was then used to represent tumor, liver and blood accumulations (%injected dose/organ) in the multiple-tumor animals. The model was found to be a good representation; in particular, it had far better agreement than single tumor predictions in the PBS mice. Differences between the single-tumor accumulations and those seen in multiple tumor examples were generally between two- and three-fold. The model also demonstrated that the result of SAP was to essentially eliminate the effect of liver targeting of tumor-secreted CEA. We conclude that an initial-phase one-tumor model can describe the decrease of accumulation of activity in the case of multiple tumors in nude mice in both untreated (PBS) and pretreated conditions. Implications for clinical imaging and therapy with monoclonal agents are discussed.

Algorithms↗
PubMed2001

Numerical selection of optimal tumor imaging agents with application to engineered antibodies.

Three analytic indicators were used to compare five members of a monoclonal antibody (Mab) family. The cognates consisted of the genetically engineered intact chimeric IgGI (cT84.66) and related engineered fragments [scFv, diabody, minibody, F(ab')2] reactive against the same epitope of carcinoembryonic antigen (CEA). All analyses were based on radioiodinated Mabs targeting to colorectal xenografts of LS174T tumors in nude mice. Affinity constants were evaluated initially. A second indicator was the imaging figure of merit (IFOM) which determines how rapidly a statistically significant tumor image can be acquired. Finally, deconvolution was used to determine tumor temporal response to an arterial bolus. This last analysis gave the possible tumor accumulation in the absence of normal tissue sequestration. Affinities were all in excess of 10(8) M-1 and were highest for the divalent Mabs. Using the IFOM criterion, an 131I label was best suited as a radiolabel for the intact (IgG) T84.66, while an 123I label indicated optimal imaging with either minibody or F(ab')2. Deconvolution analyses showed that divalent members behaved similarly while the univalent member (scFv) had a tumor residence time smaller by an order of magnitude. The diabody had the largest impulse response function, but renal uptake may limit its present usefulness.

Animals↗
PubMed2001

Utilization of the rpoB gene as a specific chromosomal marker for real-time PCR detection of Bacillus anthracis.

The potential use of Bacillus anthracis as a weapon of mass destruction poses a threat to humans, domesticated animals, and wildlife and necessitates the need for a rapid and highly specific detection assay. We have developed a real-time PCR-based assay for the specific detection of B. anthracis by taking advantage of the unique nucleotide sequence of the B. anthracis rpoB gene. Variable region 1 of the rpoB gene was sequenced from 36 Bacillus strains, including 16 B. anthracis strains and 20 other related bacilli, and four nucleotides specific for B. anthracis were identified. PCR primers were selected so that two B. anthracis-specific nucleotides were at their 3' ends, whereas the remaining bases were specific to the probe region. This format permitted the PCR reactions to be performed on a LightCycler via fluorescence resonance energy transfer (FRET). The assay was found to be specific for 144 B. anthracis strains from different geographical locations and did not cross-react with other related bacilli (175 strains), with the exception of one strain. The PCR assay can be performed on isolated DNA as well as crude vegetative cell lysates in less than 1 h. Therefore, the rpoB-FRET assay could be used as a new chromosomal marker for rapid detection of B. anthracis.

Animals↗
PubMed2001

Establishment of two vaccine-associated feline sarcoma cell lines and determination of in vitro chemosensitivity to doxorubicin and mitoxantrone.

OBJECTIVE: To establish 2 vaccine-associated feline sarcoma (VAFS) cell lines and to determine their in vitro sensitivity to the chemotherapeutic agents doxorubicin and mitoxantrone. SAMPLE POPULATION: Tumor specimens collected from 2 cats undergoing surgery for removal of vaccine-associated sarcomas. PROCEDURES: Tumor specimens were minced and treated with trypsin under aseptic conditions to obtain single-cell suspensions, which were then cultured in vitro in medium supplemented with 5% heat-inactivated fetal bovine serum. Growth rates and sensitivity after 24 hours of exposure to various concentrations (0.1 to 100 microg/ml) of doxorubicin and mitoxantrone were assessed for each cell line. Survival of cells was estimated 3 days after exposure to the 2 agents, and the concentration of each drug that resulted in a 50% reduction in the number of viable cells (IC50) was calculated. RESULTS: Two tumor-derived cell lines (FSA and FSB) were successfully established and determined to be sensitive to doxorubicin and mitoxantrone. Under the conditions tested, the IC50 of doxorubicin were 0.6 and 1.5 microg/ml for cell lines FSB and FSA, respectively. The IC50 of mitoxantrone was 0.4 microg/ml for both cell lines. CONCLUSIONS AND CLINICAL RELEVANCE: The establishment of VAFS cell lines provides a tool for the in vitro screening of antitumor drugs. Doxorubicin and mitoxantrone were effective in decreasing the number of viable cells in the 2 cell lines tested. Both of these anthracycline antibiotics have been used to treat various neoplasias in cats, and their efficacy for adjuvant treatment of vaccine-associated sarcomas should be further evaluated.

Animals↗
PubMed2000

Targeting and therapy of carcinoembryonic antigen-expressing tumors in transgenic mice with an antibody-interleukin 2 fusion protein.

The purpose of this study was to engineer a bivalent single-chain anticarcinoembryonic antigen (CEA) antibody and an interleukin 2 (IL-2) fusion protein derivative for selective tumor targeting of cytokines. The variable domains of a high affinity anti-CEA antibody, T84.66, were used to form a single-gene-encoded antibody [single-chain variable fragment joined to the crystallizable fragment, Fc (scFvFc)]. The fusion protein (scFvFc.IL-2) consisted of mouse IL-2-fused to the COOH-terminal end of the scFvFc. The engineered proteins were assembled as complete molecules and were similar to the intact anti-CEA monoclonal antibody (Mab) in antigen-binding properties. Based on IL-2 content of the fusion protein, its ability to support proliferation of CTLL-2 cells was identical with that of IL-2. Despite a molecular size similar to that of the intact Mab, the blood clearance of the fusion protein was markedly faster than that of the intact Mab or scFvFc. Incubation of radiolabeled scFvFc.IL-2 but not the intact or scFvFc antibodies in mouse serum was accompanied by the appearance of complexes, suggesting that the latter may contribute to the accelerated clearance of the fusion protein. Biodistribution and tumor targeting studies were carried out in CEA-transgenic mice bearing CEA-positive murine tumors as well as the antigen-negative parental tumor. The bivalent anti-CEA scFvFc had tumor localization properties similar to those of the intact Mab. Although fusion of IL-2 to the COOH-terminal end of the bivalent scFvFc altered its pharmacokinetic properties, the fusion antibody was able to target tumors specifically. Maximum uptake of the intact Mab, scFvFc, and scFvFc.IL-2 in CEA-positive tumors was 29.3 +/- 5.0, 19.5 +/- 2.1, and 6.6 +/- 0.9% injected dose/g, respectively. Maximum tumor localization ratios (CEA-positive/CEA-negative tumor) were similar for all three antibody types (4.6-6.0), demonstrating the antigen specificity of the tumor targeting. Significant antigen-specific targeting to CEA-positive normal tissues of transgenic mice was not observed. Although the tumor-targeting properties of the fusion protein were low, the growth of CEA-expressing (P = 0.01) but not antigen-irrelevant (P = 0.22) syngeneic tumor cells was inhibited after treatment of transgenic mice with the anti-CEA-IL-2 antibody. Therapy of CEA-expressing tumors was improved after i.v. administration of the fusion protein (P = 0.0001). These studies indicate that anti-CEA antibody-directed cytokine targeting may offer an effective treatment for CEA-expressing carcinomas. The availability of an immunocompetent CEA transgenic mouse model will also help to determine the immunotherapeutic properties of these fusion proteins.

Animals↗
PubMed2000

High-resolution microPET imaging of carcinoembryonic antigen-positive xenografts by using a copper-64-labeled engineered antibody fragment.

Rapid imaging by antitumor antibodies has been limited by the prolonged targeting kinetics and clearance of labeled whole antibodies. Genetically engineered fragments with rapid access and high retention in tumor tissue combined with rapid blood clearance are suitable for labeling with short-lived radionuclides, including positron-emitting isotopes for positron-emission tomography (PET). An engineered fragment was developed from the high-affinity anticarcinoembryonic antigen (CEA) monoclonal antibody T84.66. This single-chain variable fragment (Fv)-C(H)3, or minibody, was produced as a bivalent 80 kDa dimer. The macrocyclic chelating agent 1,4,7, 10-tetraazacyclododecane-N,N',N", N"'-tetraacetic acid (DOTA) was conjugated to the anti-CEA minibody for labeling with copper-64, a positron-emitting radionuclide (t(1/2) = 12.7 h). In vivo distribution was evaluated in athymic mice bearing paired LS174T human colon carcinoma (CEA positive) and C6 rat glioma (CEA negative) xenografts. Five hours after injection with (64)Cu-DOTA-minibody, microPET imaging showed high uptake in CEA-positive tumor (17.9% injected dose per gram +/- 3.79) compared with control tumor (6.0% injected dose per gram +/- 1.0). In addition, significant uptake was seen in liver, with low uptake in other tissues. Average target/background ratios relative to neighboring tissue were 3-4:1. Engineered antibody fragments labeled with positron-emitting isotopes such as copper-64 provide a new class of agents for PET imaging of tumors.

Animals↗
PubMed2000

Emerging mechanisms for heavy metal transport in plants.

Heavy metal ions such as Cu(2+), Zn(2+), Mn(2+), Fe(2+), Ni(2+) and Co(2+) are essential micronutrients for plant metabolism but when present in excess, these, and non-essential metals such as Cd(2+), Hg(2+) and Pb(2+), can become extremely toxic. Thus mechanisms must exist to satisfy the requirements of cellular metabolism but also to protect cells from toxic effects. The mechanisms deployed in the acquisition of essential heavy metal micronutrients have not been clearly defined although a number of genes have now been identified which encode potential transporters. This review concentrates on three classes of membrane transporters that have been implicated in the transport of heavy metals in a variety of organisms and could serve such a role in plants: the heavy metal (CPx-type) ATPases, the natural resistance-associated macrophage protein (Nramp) family and members of the cation diffusion facilitator (CDF) family. We aim to give an overview of the main features of these transporters in plants in terms of structure, function and regulation drawing on information from studies in a wide variety of organisms.

Amino Acid Sequence↗
PubMed2000

Tumor targeting with radiolabeled antibodies in a human carcinoembryonic antigen transgenic mouse model.

Mice transgenic for the carcinoembryonic (CEA) gene were used to study the biodistribution and tumor targeting of a radioiodinated monoclonal antibody (MAb), T84.66. The specificity of antibody uptake in tumors was assessed in mice bearing a CEA-transfected syngeneic tumor as well as the antigen-negative parental tumor. With high CEA-expressing tumors, the percent injected dose per gram (%ID/g) approached 30% at 48 hr. Tumor uptake in antigen-positive tumors was 5-8-fold higher than that observed in the antigen-negative parental tumors. Only antigen-positive tumors were visualized by immunoscintigraphy. The tumor targeting obtained in athymic nude mice bearing human tumor xenografts was similar to that observed with CEA-expressing murine tumors implanted in either athymic nude or transgenic mice. The degree of localization of CEA-transfected murine tumors was related with the level of antigen expression. Circulating antigen-radio-antibody complexes were not detected while blood clearance of radio-antibody was similar between transgenic and non-transgenic mice. With the exception of the large bowel, the distribution of radioiodinated MAb in normal tissues was similar in both CEA transgenic and non-transgenic mice. Increased localization of intact antibody was observed in the large bowel from transgenic mice, suggesting specific targeting to antigen-positive normal tissues. These results suggest that the CEA transgenic mouse model will be useful in the development of antibodies for radio-immunodetection and treatment of carcinomas expressing CEA.

Animals↗
PubMed2000

Evaluating changes in stable chromosomal translocation frequency in patients receiving radioimmunotherapy.

PURPOSE: The lack of any consistent correlation between radioimmunotherapy (RIT) dose and observed hematologic toxicity has made it difficult to validate RIT radiation dose estimates to marrow. Stable chromosomal translocations (SCT) which result after radiation exposure may be a biologic parameter that more closely correlates with RIT radiation dose. Increases in the frequency of SCT are observed after radiation exposure and are highly correlated with absorbed radiation dose. SCT are cumulative after multiple radiation doses and conserved through an extended number of cell divisions. The purpose of this study was to evaluate whether increases in SCT frequency were detectable in peripheral lymphocytes after RIT and whether the magnitude of these increases correlated with estimated radiation dose to marrow and whole body. METHODS AND MATERIALS: Patients entered in a Phase I dose escalation therapy trial each received 1-3 intravenous cycles of the radiolabeled anti- carcinoembryonic antigen (CEA) monoclonal antibody, 90Y-chimeric T84.66. Five mCi of 111In-chimeric T84.66 was co-administered for imaging and biodistribution purposes. Blood samples were collected immediately prior to the start of therapy and 5-6 weeks after each therapy cycle. Peripheral lymphocytes were harvested after 72 hours of phytohemagglutinin stimulation and metaphase spreads prepared. Spreads were then stained by fluorescence in situ hybridization (FISH) using commercially available chromosome paint probes to chromosomes 3 and 4. Approximately 1000 spreads were evaluated for each chromosome sample. Red marrow radiation doses were estimated using the AAPM algorithm and blood clearance curves. RESULTS: Eighteen patients were studied, each receiving at least one cycle of therapy ranging from 5-22 mCi/m2. Three patients received 2 cycles and two patients received 3 cycles of therapy. Cumulative estimated marrow doses ranged from 9.2 to 310 cGy. Increases in SCT frequencies were observed after each cycle for both chromosomes 3 and 4 in 16 of 18 patients and in at least one chromosome for the remaining 2 patients. Cumulative increases in SCT frequencies ranged from 0.001 to 0.046 with no major differences observed between chromosomes 3 and 4. A linear correlation between cumulative marrow dose and increases in SCT frequencies was observed for chromosome 3 (R2 = 0.63) and chromosome 4 (R2 = 0.80). A linear correlation was also observed between increases in SCT frequency and whole body radiation dose or administered activity (R2 = 0.67-0.89). There was less correlation between observed decrease in wbc or platelet counts and marrow dose, whole body dose, or administered activity (R2 = 0.28-0.43). CONCLUSIONS: Increases in SCT frequency were detectable in peripheral lymphocytes after low dose-rate RIT irradiation. A linear correlation was observed between increases in SCT and marrow dose, whole body dose, and administered activity. This correlation provides one of the strongest radiation dose-response and activity-response relationships observed with RIT. The detection of SCT may therefore have application as an in situ integrating biodosimeter after RIT. This biologic parameter should prove useful in comparing effects on marrow for different therapeutic radionuclides and in comparing effects of RIT and external beam radiation doses on a cGy per cGy basis. As a result, this should allow for a more direct comparison between different methods of irradiation and in further refinement of radioimmunotherapy dose estimates and dosimetry methodology.

Bone Marrow↗
PubMed2000

Midcycle and luteal elevations of follicle stimulating hormone in squirrel monkeys (Saimiri boliviensis) during the estrous cycle.

Follicle stimulating hormone (FSH) has fundamental importance in reproductive function, but its cyclic pattern has not previously been described in the squirrel monkey, due primarily to the lack of a suitable assay. An homologous radioimmunoassay (RIA) based on recombinant cynomolgus FSH measured changes in serum FSH relative to patterns of bioactive luteinizing hormone (LH), estradiol, and progesterone during the estrous cycle. FSH was observed to have a sharp peak during the late follicular phase coincident with the LH surge and then rose again during the luteal phase. Estradiol was low except for the midcycle rise, suggesting an inhibitory relationship. The rat granulosa cell in vitro FSH bioassay confirmed high levels of this hormone. Measurement of FSH in the squirrel monkey has found a pattern different from Old World primates in the luteal phase, which may provide insight into the reproductive mechanisms of this species.

Animals↗
PubMed2000

Sugar transporters in higher plants--a diversity of roles and complex regulation.

Sugar-transport proteins play a crucial role in the cell-to-cell and long-distance distribution of sugars throughout the plant. In the past decade, genes encoding sugar transporters (or carriers) have been identified, functionally expressed in heterologous systems, and studied with respect to their spatial and temporal expression. Higher plants possess two distinct families of sugar carriers: the disaccharide transporters that primarily catalyse sucrose transport and the monosaccharide transporters that mediate the transport of a variable range of monosaccharides. The tissue and cellular expression pattern of the respective genes indicates their specific and sometimes unique physiological tasks. Some play a purely nutritional role and supply sugars to cells for growth and development, whereas others are involved in generating osmotic gradients required to drive mass flow or movement. Intriguingly, some carriers might be involved in signalling. Various levels of control regulate these sugar transporters during plant development and when the normal environment is perturbed. This article focuses on members of the monosaccharide transporter and disaccharide transporter families, providing details about their structure, function and regulation. The tissue and cellular distribution of these sugar transporters suggests that they have interesting physiological roles.

Carbohydrate Metabolism↗
PubMed2000

Truncation of blood curves to enhance imaging and therapy with monoclonal antibodies.

Targeting of monoclonal antibody (Mab) to solid tumor sites is a function of the blood curve of activity versus time. It has been suggested that the blood curve be artificially reduced to approach zero so that the contrast between tumor and blood uptake is maximized. We analyzed tumor uptake as a function of the time tc of blood curve truncation. By using a convolution approach, we were able to find the optimal times for setting the blood curve to zero in either diagnostic or therapeutic animal examples. Two iodinated cT84.66 anti-CEA engineered fragments, diabody and minibody, were considered using previous data from nude mouse studies involving the LS174T colorectal tumor model. Figures of merit (FOMs) were used to compare ordinary and truncated blood curves and their associated tumor accumulations. Using a 1231 label, it was seen that the appropriate time for diagnostic truncation occurred when tumor uptake, as measured, was a maximum. The corresponding point for therapy (with 1311 as a label) was at infinite time. We also demonstrated that the use of traditional indices led to ambiguities in the choice of truncation times. The traditional therapy index, the ratio of the integral of the tumor uptake to the integral of the blood uptake, was found to be a numerical constant independent of tc. This ratio was proved to be the integral of the tumor impulse response function. Use of such convolution techniques to assess truncation of the perfused material is probably also applicable to multistep processes as well as to lesion targeting with other tumor-specific pharmaceuticals.

Animals↗
PubMed2000

Developing a framework to evaluate patient hoists.

Manual handling of patients should be avoided as far as is reasonably practical. Hoist equipment must be appropriate for the specialty's needs and staff should be trained to use it correctly. Ease of use and patient comfort are important factors to consider when choosing hoists.

Attitude of Health Personnel↗
PubMed2000

A phase I radioimmunotherapy trial evaluating 90yttrium-labeled anti-carcinoembryonic antigen (CEA) chimeric T84.66 in patients with metastatic CEA-producing malignancies.

Chimeric T84.66 (cT84.66) is a genetically engineered human/murine chimeric IgG, with high affinity and specificity to carcinoembryonic antigen (CEA). The purpose of this Phase I dose escalation therapy trial was to evaluate the toxicities, biodistribution, pharmacokinetics, tumor targeting, immunogenicity, and organ and tumor absorbed dose estimates of cT84.66 labeled with 90Y. Patients with metastatic CEA-producing malignancies were first administered 5 mCi 111In-labeled DTPA-cT84.66 (5 mg), followed by administration of the therapy dose of 90Y-labeled DTPA-cT84.66 1 week later. The therapy infusion was immediately followed by a 72-h administration of DTPA at 250 mg/m2/24 h. Dose levels of administered activity ranged from 5 to 22 mCi/m2 with three to six patients per level. Serial nuclear scans, blood samples, and 24-h urine collections were performed out to 5 days after infusion. Human antichimeric antibody response was assayed out to 6 months. Patients were administered up to 3 cycles of therapy every 6 weeks. Radiation absorbed doses to organs were estimated using a five compartment model and MIRDOSE3. Twenty-two patients received at least one cycle of therapy, with one individual receiving two cycles and two receiving three cycles of therapy. All were heavily pretreated and had progressive disease prior to entry in this trial. Reversible leukopenia and thrombocytopenia were the primary dose-limiting toxicities observed. Maximum tolerated dose was reached at 22 mCi/ m2. In general, patients with liver metastases demonstrated more rapid blood clearance of the antibody. Thirteen patients developed an immune response to the antibody. Average radiation doses to marrow, liver, and whole body were 2.6, 29, and 1.9 cGy/mCi 90Y, respectively. Dose estimates to tumor ranged from 66 to 1670 cGy (8.7 to 52.2 cGy/mCi 90Y) for each cycle of therapy delivered. Although no major responses were observed, three patients demonstrated stable disease of 12-28 weeks duration and two demonstrated a mixed response. In addition, a 41-100% reduction in tumor size was observed with five tumor lesions. 90Y-labeled cT84.66 was well tolerated, with reversible thrombocytopenia and leukopenia being dose limiting. Patients with extensive hepatic involvement by tumor demonstrated unfavorable biodistribution for therapy with rapid blood clearance and poor tumor targeting. Average tumor doses when compared with red marrow doses indicated a favorable therapeutic ratio. Stable disease and mixed responses were observed in this heavily pretreated population with progressive disease. This trial represents an important step toward further improving the therapeutic potential of this agent through refinements in the characteristics of the antibody and the treatment strategies used. Future trials will focus on the use of peripheral stem cell support to allow for higher administered activities and the use of combined modality strategies with radiation-enhancing chemotherapy drugs. Further efforts to reduce immunogenicity through humanization of the antibody are also planned. Finally, novel engineered, lower molecular weight, faster clearing constructs derived from cT84.66 continue to be evaluated in preclinical models as potential agents for radioimmunotherapy.

Animals↗
PubMed2000

Use of the feed additive sodium hexametaphosphate to prevent dental calculus in squirrel monkeys (Saimiri spp.).

Dental calculus and associated periodontal disease are serious clinical problems in captive squirrel monkeys. Calculus begins to appear as early as 2 years of age, with subsequent development of periodontal disease, dental abscessation, tooth loss and other sequelae. When used as a feed additive, sodium hexametaphosphate (HMP) retards the growth of calculus on previously cleaned teeth in rhesus monkeys, lemurs, and other species. We wanted to determine whether HMP would reduce dental calculus in squirrel monkeys (Saimiri spp.) whose teeth had not been pre-cleaned. The study animals were divided into two groups. One received a standard diet; the other received an identical diet containing the HMP additive at a concentration effective in other primate and non-primate species that had received dental cleaning prior to treatment with HMP. Teeth were graded for extent of calculus formation at the start of the study and at 3 and 6 months during HMP treatment. We compared the results from the two groups both by total score per animal and according to tooth type (e.g., incisors versus incisors in test and control groups). At the end of 6 months, dental calculus did not differ significantly between the experimental groups. Therefore, we conclude that HMP is ineffective in squirrel monkeys with preexisting dental calculus.

Animal Feed↗