Genetic susceptibility to lung cancer as determined by lymphocytic chromosome analysis

Chromosomal anomalies were analyzed in the lymphocyte cultures among 96 untreated lung cancer patients and 74 clinically normal comparison subjects. The analysis revealed that >15% of the lung cancer patients showed structural or numerical rearrangements in chromosomes 1,3,5,7,9,12,14, and 21. A case control comparison showed that these aberrations were significantly higher in chromosome 7 [odds ratio (OR) = 2.32; 95% confidence interval (CI), 1.14 and 4.82], chromosome 9 (OR = 2.61; 95% CI, 1.27 and 5.48), chromosome 12 (OR = 4.10; 95% CI, 1.40 and 14.54), and chromosome 21 (OR = 7.75; 95% CI, 1.73 and 70.80) of the patients than in the controls. However, only chromosome 9 (OR = 3.57; 95% CI, 1.33 and 9.46) and chromosome 21 (OR = 6.94; 95% CI, 3.15 and 9.98) retained significance after stratifying on smoking status. Among the lung cancer patients, the breakpoints cluster in specific regions of some of these chromosomes. These regions are 1p13-q21, 3q21-q13, 7p12-q12, 7q12-q12,7q22, 7q32, 9p13-q13, 12p13, 14q11, and 14q32. The distribution of lung cancer patients, according to histological types, showed that aberrations in chromosomes 1,7, and 9 dominated the scenario of chromosomal changes in non-small cell lung carcinomas. Thus, the data on lymphocytic chromosomal rearrangements in lung cancer patients not only indicate the importance of specific genetic changes in the etiology of lung cancer but also emphasizes the putative role of such analysis in determining primary genetic abnormalities in the large heterogeneous group of lung cancers.

Timely administration of extract of Ferula jaeschkeana causes luteolysis in the ovary of cyclic guineapig

Effect of hexane extract of Ferula jaeschkeana has been studied on corpora lutea of adult cyclic guinea-pigs. Administration of extract showed duration dependent luteolytic changes in the corpora lutea. Its administration for first three days from the onset of estrus caused significant decrease in the diameter of corpora lutea in the ovary at day 10 of cycle. Ovarian wet weight, proteins and glycogen contents were decreased while the activity of acid phosphatase in the ovary was increased. These luteolytic changes in the ovary have also been observed in the histological findings. Administration of extract for other durations (4-6, 7-9 or 10-12 of cycle) did not cause any change at 10th and 16th day.

Regulation of the ribosomal-RNA gene-expression in fibroblasts isolated from different human or murine tissues

Ag-NOR stainings of the fibroblastic cultures derived from skin, lung and kidney of mice and humans have shown differential regulation of rRNA gene expression. Ag-NOR activities were found to be highest in the fibroblasts derived from the lung and the lowest in the skin-derived metaphases from both mice and humans and they were intermediate in the fibroblasts of kidney from both these species. Our observations indicate further that fibroblasts derived from different tissues are different not only in producing organ-specific growth factors but also in differential expression of ribosomal cistrons. This difference can also explain why orthotopic implantation of human tumor cells into nude mice is preferential compared with ectopic implantation in tumor take and metastasis.

Chromosomal markers associated with metastasis in two colon cancer cell lines established from the same patient

The purpose of this study was to identify specific chromosomal abnormalities that might be involved in colon cancer metastasis. For this reason, we performed extensive karyotypic analysis on two colon cancer cell lines (SW480 and SW620) established from two surgical biopsies taken at different intervals and representing different stages of the disease from the same patient. Despite the karyotypic heterogeneity, several marker chromosomes were shared between the two cell lines, indicating their common origin. We hypothesized that these shared chromosomal aberrations might be critical for the continuous growth of the tumor cells and, therefore, were retained through progression of the disease. Duplication of 16q and new or additional structural chromosomal abnormalities involving breakpoints 3p21, 8p11, 10q25, 13q14, 14q11 and 15q15 were observed as the characteristic anomalies only in the SW620 cell line. As SW620 was established from the abdominal metastatic lesion of the patient, we postulated that the acquisition of these new markers in the progression steps of the primary tumor might represent "hot-spots" that possibly contain genes crucial for metastatic potential in colon cancer.

Multiple specific chromosomal alterations in a rat ascitic histiocytoma 'AK-5'

In the rat ascitic histiocytoma, AK-5, chromosome numbers vary between 33 and 41 with a peak at 40 chromosomes. None of the metaphase spreads showed double minute chromosomes. The karyotype of this tumor was characterized by hypodiploid chromosome constitution. Giemsa banding analysis revealed 12 clonal marker chromosomes (M1-M12). Tentative identification of these markers were: M1 = ins(1q); M2 = t(5;?); M3 = t(8;10); M4 = t(8;?); M5 = t(10;X); M6 - t(15;?); M7 = t(5;6); M8 = del(13p); M9-M12 = unidentified. M3 being a large near metacentric chromosome serves as a characteristic marker for this tumor. All marker chromosomes except M2 and M4 were present in single copy per cell. In some metaphases M2 was present in 2 copies while M4 was present in 2 or 3 copies per cell. The total cell cycle duration of AK-5 cells was 15.5 h and the different phases, G1, S, G2 + M were estimated as 1.2, 12.2, and 2 h, respectively.

Chromosome end associations, telomeres and telomerase activity in ataxia telangiectasia cells

Cells derived from individuals with ataxia telangiectasia (AT) show enhanced spontaneous levels of chromosomal abnormalities and are sensitive to ionizing radiations and radiomimetic drugs, as evidenced by decreased survival and increased chromosome aberration frequencies at mitosis when compared with normal cell lines. The higher base line frequencies of chromosome aberrations in part involve chromosome end-to-end associations as seen at metaphase. Since telomeres of tumor cells and aging tissues are often reduced in length, chromosome end associations may be due to loss of telomeric repeats. We studied the chromosome behavior and telomeres of two ataxia telangiectasia lymphoblastoid cell lines compared to two normal control cell lines. The ataxia telangiectasia cell lines showed higher frequencies of chromosome end associations both at metaphase and in interphase, determined in prematurely condensed chromosomes of G1 and G2 cells. They also showed higher frequencies of chromosomal breaks at metaphase and fewer telomeric signals determined using fluorescent in situ hybridization with a (TTAGGG)n probe. The frequency of telomeric repeats was variable in the ataxia telangiectasia cell lines (4.3 and 8.2 kb) compared to the normal cell lines (9.6 and 12 kb) and an inverse correlation between telomere length and chromosome end associations was observed. Both ataxia telangiectasia cell lines showed more robust telomerase activity than the normal cell lines, precluding defective enzymatic capacity as the basis for the chromosome end associations. It is possible that chromatin structure in the form of telomere-nuclear matrix interactions are variant in ataxia telangiectasia cells negatively influencing telomerase function and contributing to telomere associations.

Clonal evolution of an immunoblastic type non-Hodgkin's lymphoma with der(6)t(1;6)(q11;p11) as its primary cytogenetic abnormality

Recurrent pleural effusions from a 45-year-old man who was diagnosed as having non-Hodgkin's lymphoma of immunoblastic type were studied cytogenetically. The majority of the metaphases were tetraploid, but there were also lymphoma cells observed with pseudodiploid chromosome constitutions. Cytogenetic analysis by G-banding revealed the existence of at least two cell populations. The karyotype of the minor pseudodiploid clone, which exhibited partial trisomy of 1q11qter and monosomy of 6p11pter as sole abnormalities, was 46,XY,der(6)t(1;6)(q11;p11). The karyotype of the major clone was 92,XXYY,-1,der(6)t(1;6)(q11;p11)x2, +9. The ancestral diploid clone, carrier of the balanced translocation involving chromosomes 1 and 6, was not observed even in the first pleural effusion harvest. The high proportion of tetraploid cells in the recurrent effusions was an indication that these cells were favorably selected in the environment of the somatic cavity. Our cytogenetic findings suggest that partial trisomy of 1q may be a crucial secondary chromosomal abnormality in highly malignant non-Hodgkin's lymphoma. This genetic imbalance was predetermined from the primary abnormality and may be responsible for further tumor progression, as suggested from the clonal evolution in this particular case and, therefore, may be associated with the aggressive biologic behavior of malignant cells.

Chromosome alterations in cancer development and apoptosis

Normal somatic cells are programmed to die (or undergo apoptosis) whereas cancer cells program themselves to survive. Some of the cytogenetic alterations that might be involved in apoptosis and continuous cell proliferation of normal and cancer cells such as shortening of telomeres, formation of dicentric chromosomes, transfer of telomeric DNA to the homologous chromosomes, malfunction (inactivation) of the centromeres, endoreduplication of chromosomes and other structural and numerical chromosome abnormalities are discussed here.

High frequency of telomeric association in a family with multiple congenital neoplasia

Chromosomal analysis of the peripheral blood cultures of a married couple whose second pregnancy gave birth to twin daughters with multiple congenital malignancies revealed normal karyotypes of 46,XX and 46,XY, respectively. However, in the father's blood, 23.3% of metaphases showed telomere-telomere associations involving single-single and double-double chromatids. Such associations were not observed in the metaphases of the mother. We speculate from these observations that the father's genotype may somehow be responsible for the congenital malignancies in their twin daughters.

Androgen-independent cancer progression and bone metastasis in the LNCaP model of human prostate cancer

Our laboratory has previously reported on the derivation of LNCaP cell sublines from LNCaP tumors maintained in castrated and intact athymic male mice. These LNCaP sublines differ from the parental line in tumorigenicity and androgen dependence. This paper demonstrates that one of these sublines acquired metastatic potential. When inoculated either s.c. or orthotopically, the C4-2 subline metastasized to the lymph node and bone with an incidence of 11-50%. Interestingly, the incidence of osseous metastasis was higher in castrated than in intact male hosts. We evaluated the chromosomal, immunohistochemical, and biochemical characteristics of the LNCaP sublines derived from C4-2 tumors that metastasized to the lymph node and bone. Cytogenetic analysis showed that all sublines were human and shared common marker chromosomes with the parental LNCaP cells. This experimental human prostate cancer model may permit, for the first time, the study of the molecular mechanisms underlying human prostate cancer metastasis.

Derivation of androgen-independent human LNCaP prostatic cancer cell sublines: role of bone stromal cells

A model of human prostate cancer was established to study cellular interaction between prostate cancer and bone stroma in vivo. In this model, subcutaneous co-injection of 2 non-tumorigenic human cell lines--LNCaP, a prostate cancer cell line, and MS, a bone stromal cell-line--into intact adult male mice resulted in formation of carcinomas that secreted prostate-specific antigen (PSA), a clinically useful human serum prostate cancer marker. In castrated hosts, upon cellular interaction with bone fibroblasts, we observed the progression of these tumors from an androgen-dependent (AD) to an androgen-independent state (AI). We derived 4 LNCaP cell sublines from the chimeric LNCaP/MS tumors: the M subline from intact hosts and the C4, C4-2 and C5 sublines from castrated hosts. The LNCaP sublines had chromosomal markers similar to those of the parental LNCaP cells and distinctly different from those of the MS bone stromal cell line. Although the parental and derived cell lines expressed similar steady-state levels of ornithine decarboxylase transcript, the sublines expressed 5- to 10-fold higher basal steady-state levels of PSA transcript than did the parental LNCaP cell line. The LNCaP sublines formed 13- to 26-fold more soft-agar colonies than the parental LNCaP cell line. The sublines became tumorigenic, yielding an incidence of tumors in intact athymic mice of 7-75%. The LNCaP sublines C4 and C5 (but not the parental and M cell line) formed tumors in castrated hosts when co-injected with bone fibroblasts. A second-generation LNCaP subline, C4-2, was derived from a chimeric tumor induced by co-inoculating castrated mouse with C4 cells and MS cells. We found that C4-2 subline was tumorigenic when inoculated into castrated hosts in the absence of inductive fibroblasts. Moreover, C4-2 was the only subline capable of forming soft-agar colonies when cultured in serum-free medium. In comparison with the parental LNCaP cells, the C4-2 subline expressed lower steady-state levels of androgen receptor (AR) protein and mRNA transcript and lost its androgen responsiveness in vitro. Our results suggest that certain genetic traits of prostate cancer cells may be selected or altered through an "adaptive" mechanism that involves cellular interaction with the bone stromal cells.

A tumor suppressor locus within 3p14-p12 mediates rapid cell death of renal cell carcinoma in vivo

High frequency loss of alleles and cytogenetic aberrations on the short arm of chromosome 3 have been documented in renal cell carcinoma (RCC). Potentially, three distinct regions on 3p could encode tumor suppressor genes involved in the genesis of this cancer. We report that the introduction of a centric fragment of 3p, encompassing 3p14-q11, into a highly malignant RCC cell line resulted in a dramatic suppression of tumor growth in athymic nude mice. Another defined deletion hybrid contained the region 3p12-q24 of the introduced human chromosome and failed to suppress tumorigenicity. These data functionally define a tumor suppressor locus, nonpapillary renal carcinoma-1 (NRC-1), within 3p14-p12, the most proximal region of high frequency allele loss in sporadic RCC as well as the region containing the translocation breakpoint in familial RCC. Furthermore, we provide functional evidence that NRC-1 controls the growth of RCC cells by inducing rapid cell death in vivo.

Interphase cytogenetics in paraffin-embedded sections from renal cortical neoplasms. Correlation with cytogenetic and flow cytometric DNA ploidy analyses

Nonisotopic in situ hybridization (ISH) was performed on archival tissue sections from six renal cortical neoplasms and corresponding normal kidney tissue using pericentrometric (alpha-satellite) probes to chromosomes 1, 3, 7, 8, 10, 11, 12, 16, and 17. The results were correlated with classic cytogenetic analyses and flow cytometric DNA ploidy findings of these neoplasms. Our study shows that intratissue and intertissue ISH spot counts were generally homogeneous in normal kidney tissue and markedly heterogenous in tumor specimens. In all cases the correlation between the DNA Index and the ISH spot numbers was statistically significant. A correlation between modal and numerical chromosomal findings by cytogenetic analysis and ISH spot counts was found in three cases and was discordant in three cases. Our results also show that chromosomes 1, 3, 7, and 17 appear to manifest more propensity for aneuploidy than chromosomes 8, 10, 11, 12, and 16. We conclude that 1) numerical chromosomal aberrations by interphase in-situ hybridization correlate with DNA ploidy analysis in these tumors; 2) certain chromosomes may be more prone to aneuploidy than others; 3) determination of monosomy by ISH is less reliable on paraffin-embedded sections; and 4) the ISH technique complements conventional cytogenetic analysis in providing more information for the determination of cytogenetic aberrations and clonal heterogeneity in solid neoplasms.

Development of tumorigenicity and rearrangement of chromosome 1 correlates with down-regulation of cell-surface glycoproteins in human mammary carcinoma cell line

In the current study, attempts were made to identify any products of normal breast cell genes, that may become inactivated in the malignant counterparts. Using an immune-tolerization/immunization procedure of generating antibody, two different cell-surface glycoproteins termed luminal epithelial antigen, LEA.92 and LEA.135 were identified. LEA.92 and LEA.135 expressions on MEC in a culture model-system, that reflect various steps of neoplastic transformation were detected on normal or immortalized MEC lines that were non-tumorigenic in nude mice. Furthermore, no rearrangement of chromosome 1 was observed in those cells. In contrast, both glycoproteins were undetectable on oncogenically transformed or established lines of mammary carcinoma cells that were tumorigenic. LEA.92 or LEA.135 negative cell lines exhibited a partial deletion of their chromosome 1. In tissue sections, LEA.92 expression was detected on the apical plasma membrane of normal and hyperplastic but not on the malignant mammary or extramammary epithelial cells (MEC). However, unlike LEA.92, LEA.135 was detected on certain cases of primary breast carcinoma cells, irrespective of morphological differentiation, in tissue sections.

Nonrandom chromosomal abnormalities in lymphocyte cultures of individuals with colorectal polyps and of asymptomatic relatives of patients with colorectal cancer or polyps

We studied chromosomal alterations in the peripheral blood lymphocytes of 10 individuals with colorectal polyps and 10 asymptomatic first-degree relatives of patients with colon cancer or colorectal polyps. The analysis was performed on T-lymphocytes using short term blood cultures and on B-lymphocytes by establishing lymphoblastoid cell lines by Epstein-Barr virus transformation. Chromosomal changes were not common in T- and B-lymphocytes. Chromosomes 1 and 5 were most frequently involved in numerical or structural changes in the patients with polyps as well as in the asymptomatic relatives. These alterations were observed in either the T-lymphocytes or the B-lymphocytes but rarely in both, thus accentuating the importance of studying both the cultures concurrently. Chromosome 5, which is known to play an important role in the development of adenomatous polyps, was found to be involved in 6 (60%) of 10 patients with polyps and 4 (40%) of 10 asymptomatic relatives. These findings show that lymphocytic chromosomal analysis can aid in identifying individuals who are genetically susceptible and are at a higher risk of developing colorectal cancer. Because lymphocytic chromosomal analysis is relatively simple and inexpensive, we expect that it will be very useful in screening asymptomatic individuals who are at a higher risk due to inherited or environmental factors.

Replication of the A7(74) strain of Semliki Forest virus is restricted in neurons

In neonatal mice the A7(74) and L10 strains of Semliki Forest virus (SFV) are virulent. In 3- to 4-week-old mice the L10 strain is virulent, the A7(74) strain is avirulent. Following intraperitoneal inoculation of 3- to 4-week-old mice both strains produce a transient plasma viremia. This is cleared by IgM antibodies. IgG antibodies of all subclasses are produced. The distribution of viral RNA in the brain as determined by autoradiographic analysis of in situ hybridizations shows that in all cases virus is first apparent as small foci of infected cells around cerebral capillaries. In both neonatal and 3- to 4-week-old mice infected with L10 or neonatal mice infected with A7(74), infection spreads rapidly from the original foci to infect large areas throughout the brain. Both neurons and glial cells are infected resulting in pycnosis and death of the animals. In the brains of 3- to 4-week-old mice infected with A7(74) virus there is little spread from the original perivascular foci. Again neurons and oligodendrocytes are infected but cellular destruction is minimal. The same pattern of A7(74) infection is observed in 3- to 4-week-old athymic nu/nu mice and mice with severe combined immunodeficiency, indicating that failure to spread is not related to specific immune responses. Furthermore, in nu/nu and SCID mice the small restricted foci of A7(74) infection persist. Comparison of the replication of these two viruses by electronmicroscopy shows that although A7(74) virus replicates completely in the neurons of neonatal mice, the virus is unable to bud from the neurons of 3- to 4-week-old mice and aggregates of viral RNA and capsid accumulate. We conclude that there is an age-related restriction of A7(74) replication in mouse neurons and that this restriction is not associated with the maturity of virus-specific immune responses but probably reflects age-related changes in neurons.

Transformation of immortal, non-tumorigenic osteoblast-like human osteosarcoma cells to the tumorigenic phenotype by nickel sulfate

Epidemiological studies have indirectly linked compounds of chromium, nickel and arsenic to human carcinogenesis. However, there is no evidence that metal compounds can transform human cells to the tumorigenic phenotype in culture. We show here that exposure to 36 microM NiSO4 for 48-96 h results in transformation of an immortal, nontumorigenic, osteoblast-like cell line, HOS TE85, to the tumorigenic phenotype. Continuous passaging following treatment leads to the formation of a few dense foci. The cells isolated and expanded from the foci are morphologically transformed, and form anchorage-independent colonies of the size and abundance comparable to that formed by Kirsten murine sarcoma virus transformed HOS TE85 cells. The transformed cells from tumors in nude mice, have enhanced levels of plasminogen activators and have lost the ability to form model bone matrix on extended culture in the presence of ascorbic acid and beta-glycerophosphate. A number of cell lines have been established from nude mouse tumors. Cytogenetic analysis reveals 16 marker chromosomes and an aberrant chromosome 16. This is the first report of the transformation of a human cell line to tumorigenic phenotype by a metal carcinogen.

Cytogenetic abnormalities in colon cancer patients: a comparison of T- and B-lymphocytes

Cytogenetic analysis of peripheral blood lymphocytes of 19 colorectal cancer patients was carried out in short term blood cultures (T-cells) as well as in Epstein-Barr virus transformed B-cell lymphoblastoid cell lines. One hundred Giemsa-banded metaphases from the T lymphocytes and 50 metaphases from the B lymphocytes of each patient were evaluated for cytogenetic abnormalities. Clonality was not observed in every paired sample. Structural and/or numerical aberrations were most frequent in chromosomes #1, #2, #5, #7, #9, #12, #14, #17, #18 and #21. Aberrations among these chromosomes could be observed individually in either of the cultures, which proves that the analysis of both cultures (T and B cells) is complementary to each other. In some cases involving multiple primary cancers it was interesting that the specific chromosomal change, crucial for a particular malignancy, was identified only in the lymphoblastoid cell line analysis. This supports the notion that B-cell analysis can serve as a useful adjunct to the study of short-term blood cultures and also poses a question as to whether the specific chromosomal changes observed in the analysis are confined to the B-cell lineage.

Characterization of the DiFi rectal carcinoma cell line derived from a familial adenomatous polyposis patient

The DiFi human colorectal cancer cell line was recently established from a familial adenomatous polyposis patient with extracolonic features characteristic of the Gardner syndrome. These cells have now been propagated for 150 passages in standard culture media and vessels without feeder layers or collagen coatings. They retain features of colonic epithelial cells such as surface microvilli, secretory vesicles, and desmosomes. Cytosol of DiFi cells contains a high level (502 U/mg protein) of the mucin CA 19-9. In addition, DiFi cells produce carcinoembryonic antigen, and induce tumors in athymic mice. Cytoskeleton analysis of DiFi cells by fluorescence microscopy showed a pronounced disorganization of actin cable structure. The isozyme genetic signature of DiFi cells is unique (0.01 probability of finding the same genetic signature in a different cell line), differs from that of HeLa cells, and has expressional features seen in other colorectal cell lines. The DiFi cell karyotype is tetraploid, contains many marker chromosomes, and shows numerous episomal particles. Two copies of chromosome 18 were absent, and only a single normal chromosome 17 was found. This parallels detection of allelic losses from DiFi cell DNA at loci on chromosomes 17p and 18 using molecular (cDNA) probes. DiFi cells clearly express transcripts for the c-myc proto-oncogene, the c-myb proto-oncogene, and the p53 tumor suppressor gene. Transforming growth factor beta inhibits DiFi cell growth in soft agar and suppresses c-myc expression in these cells. The value of this cell line in the study of genetic alterations in colorectal cancer is discussed.

Lymphotoxin is an autocrine growth factor for Epstein-Barr virus-infected B cell lines

Because human lymphotoxin (LT) was originally isolated from a lymphoblastoid cell line, we investigated the role of this molecule in three newly established Epstein-Barr virus (EBV)-infected human B cell lines. These lines were derived from acute lymphoblastic leukemia (Z-6), myelodysplastic syndrome (Z-43), and acute myelogenous leukemia (Z-55) patients who had a prior EBV infection. Each lymphoblastoid cell line had a karyotype that was different from that of the original parent leukemic cells, and all expressed B cell, but not T cell or myeloid surface markers. In all three lines, rearranged immunoglobulin heavy chain joining region (JH) bands were found, and the presence of EBV DNA was confirmed by Southern blotting. Z-6, Z-43, and Z-55 cell lines constitutively produced 192, 48, and 78 U/ml LT, respectively, as assessed by a cytotoxicity assay and antibody neutralization. Levels of tumor necrosis factor (TNF) were undetectable. Scatchard analysis revealed that all the cell lines expressed high-affinity TNF/LT receptors with receptor densities of 4197, 1258, and 1209 sites/cell on Z-6, Z-43, and Z-55, respectively. Furthermore, labeled TNF binding could be reversed by both unlabeled TNF, as well as by LT. Studies with p60 and p80 receptor-specific antibodies revealed that the three lines expressed primarily the p80 form of the TNF receptor. When studied in a clonogenic assay, exogenous LT stimulated proliferation of all three cell lines in a dose-dependent fashion at concentrations ranging from 25 to 500 U/ml. Similar results were obtained with [3H]TdR incorporation. Monoclonal anti-LT neutralizing antibodies at concentrations of 25-500 U/ml inhibited cellular multiplication in a dose-dependent manner. It is interesting that in spite of a common receptor, TNF (1,000 U/ml) had no direct effect on Z-55 cell growth, whereas it partially reversed the stimulatory effect of exogenous LT. In addition, TNF inhibited Z-6 and Z-43 cell proliferation, and its suppressive effect was reversed by exogenous LT. Both p80 and p60 forms of soluble TNF receptors suppressed the lymphoblastoid cell line proliferation and their inhibitory effect was partially reversed by LT. Our data suggest that (a) LT is an autocrine growth factor for EBV-transformed lymphoblastoid B cell lines; and (b) anti-LT antibodies, soluble TNF/LT receptors, and TNF itself can suppress the growth of lymphoblastoid cells, probably by modulating or competing with LT.(ABSTRACT TRUNCATED AT 400 WORDS)

In vitro evaluation of calcium pectinate: a potential colon-specific drug delivery carrier

Calcium pectinate (CaP)--the insoluble salt of pectin--can potentially be used as a colon-specific drug delivery system. The use of CaP as a carrier was based on the assumption that, like pectin, it can be decomposed by specific pectinolytic enzymes in the colon but that it retains its integrity in the physiological environment of the small bowel. The biodegradation of the carrier was characterized by monitoring the percent cumulative release of the insoluble drug indomethacin, incorporated into pectin or CaP matrices. Compressed tablets of pectin and indomethacin were analyzed for degradation in the presence of Pectinex 3XL, a typical pectinolytic enzyme mixture, and in the presence of the human colonic bacterium Bacteroides ovatus. The degradation of CaP-indomethacin tablets was assessed in the presence of Pectinex 3XL and in rat cecal contents. The release of indomethacin was significantly increased (end-time percentage cumulative release vs control) in the presence of Pectinex 3XL (89 +/- 20 vs 16 +/- 2 for CaP tablets), Bacteroides ovatus (12 and 22 vs 5.2 for pectin tablets), and rat cecal contents (61 +/- 16 vs 4.9 +/- 1.1 for CaP tablets). The weight loss of tablet mass was significantly higher (end-time dry weight vs control) in the presence of Pectinex 3XL (0 vs 75 +/- 6% of initial weight for CaP tablets). These findings indicate the potential of CaP, compressed into tablets with insoluble drug, to serve as a specific drug delivery system to the colon.