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Biomedical subjects

S M Walker

Publications and source records attributed to S M Walker.

At least 73 records · Page 4Linked to original sources
PubMed1988

Influence of organ environment on the growth, selection, and metastasis of human colon carcinoma cells in nude mice.

The purpose of these studies was to determine whether the biological and metastatic behaviors of tumor cells isolated from fresh surgical specimens of human colon carcinomas are influenced by the isolation method and the organ site of implantation and growth in nude mice. Three surgical specimens were obtained from three different patients. Two tumors were primary human colorectal carcinomas (HCC) classified as Dukes' B2 (KM12) and Dukes' D stages (KM20), and the third was from a liver metastasis (KM23). The tumors were enzymatically dissociated, and viable cells were implanted into the subcutis or spleen of different nude mice or were established in culture. Tumors developed in both sites of implantation, but hepatic metastases were found only in those nude mice that received splenic implantations of HCC cells. Cells from Dukes' D stage tumors produced more hepatic disease than cells from the Dukes' B tumor. Cells of the parental KM12C (culture) were injected into the spleen or cecum of nude mice to produce experimental and spontaneous hepatic metastases, respectively. HCC lesions were harvested from livers of nude mice and established as individual cell lines in culture. This procedure yielded cell lines KM12SM (spontaneous metastasis) and KM12L1 (experimental metastasis). The selection cycle for cells implanted into the spleen was repeated three more times to produce the cell line designated KM12L4. Cells of the parental KM12C and the three selected variants were injected into nude mice by different routes: i.v., s.c. into the cecum, and into the spleen. Subsequent to implantation into the spleen, all cell lines were shown to be tumorigenic. Cells from the selected KM12L4 and KM12SM lines produced a significantly higher number of experimental liver metastases than the parental cells. Moreover, subsequent to the injection into the cecum, cells of the once-selected KM12SM (for spontaneous metastasis) produced a higher incidence of spontaneous liver metastasis than all other lines. The human origin of all the lines was confirmed by isoenzyme and karyotype analyses. The two highly metastatic lines (KM12L4 and KM12SM) were tetraploid and produced elevated levels of type IV collagenolytic activity. Collectively, the results demonstrate that the orthotopic implantation of HCC cells into the appropriate organ environment can be used for efficient isolation and for study of metastatic subpopulations of cells from human colon carcinoma.

Animals↗
PubMed1988

In vivo selection of highly metastatic cells from surgical specimens of different primary human colon carcinomas implanted into nude mice.

The purpose of these studies was to select and isolate cells with increased liver-metastasizing potential from heterogeneous primary human colon carcinomas (HCCs). Cells derived from a primary HCC classified as Dukes' stage B2 were directly established in culture or were injected into the subcutis, cecum, or spleen of nude mice. Progressively growing tumors were excised, dissociated, and established in culture. Subsequent to implantation into the cecum or spleen of nude mice, cells from all four lines produced only a few liver tumor foci. HCC cells from the few liver metastases were expanded in culture and then injected into the spleen of nude mice to provide a source for further cycles of selection. With each successive in vivo selection cycle, the metastatic ability of the isolated propagated cells increased. Four cycles of selection yielded cell lines with a very high metastatic efficiency in nude mice. In parallel studies using another primary HCC classified as Dukes' stage D, we isolated cell lines that were highly metastatic in nude mice. Successive selection cycles for growth in the liver increased the metastatic properties of the HCC cells, albeit to a lesser extent than it did those of the Dukes' B2 stage HCC. The ability of the HCC cells to produce liver metastases was not due to simple trapping in the liver. In vivo distribution studies using [125I] iododeoxyuridine-labeled tumor cells revealed that, shortly after injection into the spleen, a comparable number of cells with either low or high metastatic properties arrested in the liver. The differences between the low- and high-degree metastatic cells became apparent by 24 h after injection and, by 72 h, only highly metastatic cells survived in the liver. These results demonstrate that hepatic metastasis by HCC cells is a selective process and that the nude mouse model can be useful for isolating highly metastatic HCC cells and for studying the relevant host organ factors that regulate the pathogenesis of metastasis.

Animals↗
PubMed1988

Relationship between the rate of appearance of oxprenolol in the systemic circulation and the location of an oxprenolol Oros 16/260 drug delivery system within the gastrointestinal tract as determined by scintigraphy.

1. The position in the gastrointestinal tract of an orally administered oxprenolol Oros drug delivery system labelled with technetium-99m DTPA was followed by gamma scintigraphy, and the corresponding plasma drug concentration-time profiles after oral and i.v. administration were used to relate pharmacokinetic and transit data. 2. Gastric emptying time (0.8 +/- 0.4 h, mean +/- s.d.), and the time to arrival in the colon (3.8 +/- 0.7 h) were reasonably consistent after administration of the Oros system to fasted subjects, as were the calculated small intestine transit times (3.0 +/- 0.7 h). As expected there were wide individual variations in colonic transit, so that recorded values for total transit ranged from 6 to 32 h (median, 24.7 h). 3. Absorption of oxprenolol occurred throughout the GI tract including the colon. Plasma drug concentration-time profiles and input functions (calculated by deconvolution) could be related to transit behaviour and in vitro release. Inflexions in the calculated rate of drug input when the Oros system was located in the colon corresponded with periods of stagnation at the hepatic and splenic flexures in two subjects and the ileocaecal junction in two others. The mechanism of these changes is unclear.

Adolescent↗
PubMed1987

Serum-mediated suppression of nonspecific B-cell activation. III. Selective inhibition of the polyclonal B-cell response by normal mouse serum.

Normal, nonimmune adult serum is known to inhibit in vitro immune responses when present in sufficient amounts. The significance of inhibition of the immune response by serum, however, is not known. Previous work suggested that normal mouse plasma or serum (NMS) was selectively more inhibitory to nonantigen-specific (e.g., polyclonal) as compared to antigen-specific responses. This led to the hypothesis that constituents of serum (or plasma) may serve naturally to minimize the polyclonal type of antibody response, preserving immune specificity. The present study further examined the effect of NMS on polyclonal versus antigen-specific antibody responses. Under the in vitro assay conditions used, 0.5% NMS supported bacterial endotoxin (ET)-induced mitogenic and polyclonal B lymphocyte responses, antigen (SRBC, TNP-KLH)-specific antibody (IgM, IgG) responses, and antigen-induced or -specific T-lymphocyte proliferative responses, while 5% NMS inhibited all of these responses. However, antigen-specific T-lymphocyte responses could be restored by a 10-fold increase in the antigen concentration and antigen-specific antibody responses could be restored by the addition of ET (10 micrograms/ml) as adjuvant. On the other hand, the mitogenic response to ET remained suppressed regardless of ET concentration. Thus, despite significant reduction of the mitogenic and polyclonal properties of ET in 5% NMS (greater than 70% suppression), sufficient antigenic stimuli permitted optimal specific T- and B-cell responses. Many naturally occurring antigens, e.g., bacterial, fungal, and viral, have inherent B-cell mitogenic and polyclonal activity in addition to adjuvanticity and the presence of the serum inhibitory factor may serve to minimize their indiscriminate polyclonal stimulation of antibody.

Adjuvants, Immunologic↗
PubMed1987

The role of humoral immunity in Lactobacillus casei cell wall induced arthritis.

Although both cellular and humoral immunity have been shown to play important roles in the development of collagen induced arthritis, their roles in the pathogenesis of bacterial cell wall induced arthritis remain unclear. Previous studies of humoral immunity in bacterial cell wall induced arthritis were carried out in outbred animals and measured the humoral response to only the eliciting bacteria. We compared the humoral immune responses of arthritis susceptible Lewis and arthritis resistant Fisher rats after the injection of arthritogenic group B Lactobacillus casei cell wall fragments. Both strains developed significant IgG and IgM responses to the Lactobacillus casei cell wall fragments. Neither strain developed a significant immune response to types I, II, IX or 1a2a3a collagens. These data suggest that humoral immune responses to the Lactobacillus casei cell wall fragments and types I, II, IX, or 1a2a3a collagens do not play a significant role in determining the differing arthritis susceptibilities of Lewis and Fisher rats.

Animals↗
PubMed1987

Determination of ovarian steroid hormone levels in saliva. An overview.

Assessment of ovarian activity based on saliva samples has proven particularly useful in studies of women in well-developed countries and is potentially of even greater value in women of lower socioeconomic status in Third World countries. Assay techniques suitable for measuring low concentrations of steroids in saliva have become available only recently, so data derived from salivary sampling regimens are far less extensive than those based on plasma or urinary sampling procedures. Collecting saliva is an attractive alternative to the more conventional procedures because of the ease of frequent collection and freedom from religious and social constraints. Simple, direct assays for salivary progesterone have been established, but those for estradiol require considerably more research before becoming useful in routine practice. Predicting ovulation with data derived from saliva sampling awaits the development of more suitable assays for salivary estradiol.

Estradiol↗
PubMed1986

Immunohistochemical identification of prolactin and 24K protein in secretory endometrium.

Inadequate endometrial differentiation is a cause of infertility and recurrent pregnancy loss. Diagnostic histologic dating criteria may be supplemented by the immunohistochemical identification of protein markers in late secretory endometrium. Late secretory endometrium has been shown to contain prolactin. The authors report the immunohistochemical localization of prolactin and 24K protein in late secretory endometrium using monoclonal antisera and the dinitrophenyl hapten sandwich-staining technique. The appearance of these proteins in decidualized stromal cells of late secretory endometrium may provide a more specific indicator of endometrial development and differentiation, if their late appearance or absence can be correlated with pregnancy wastage.

Antibodies, Monoclonal↗
PubMed1986

Plasma noradrenaline in Goldblatt models of renovascular hypertension in the rat, before and after surgical reversal.

Plasma noradrenaline (NA), blood pressure (BP) and heart rate (HR) were measured simultaneously in conscious rats under basal conditions in the early phase (4-6 weeks) of one-kidney, one-clip hypertension (1K1C), in the early (4-6 weeks) and chronic (greater than 16 weeks) phases of the two-kidney, one-clip model (2K1C) and in age-matched loose clip control animals before and 2 days after unclipping. The elevated BP in all three hypertensive groups fell to normal after unclipping, whereas removal of the constricting clip in loose clip controls had no effect on BP. Plasma NA was elevated in 1K1C hypertension (P less than 0.05) and fell slightly but non-significantly on unclipping. However, in the early phase of 2K1C hypertension plasma NA was unaltered before and rose significantly (P less than 0.05) after unclipping. Plasma NA did not change with unclipping in the chronic phase of 2K1C hypertension and was not different from controls. Unclipping loose clip control animals produced no change in plasma NA. Changes in HR on unclipping followed a similar pattern to changes in plasma NA: changes in the two variables were significantly correlated in all three models (1K1C: r = 0.61, P less than 0.005; early 2K1C: r = 0.45, P less than 0.05; chronic 2K1C: r = 0.62, P less than 0.01). However, BP was only correlated with plasma NA in 1K1C hypertension (r = 0.49, P less than 0.02) and not in either phase of the 2K1C model. There was also a highly significant correlation between HR and plasma NA in 1K1C hypertension (r = 0.71, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Seminal acid phosphatase in relation to fertility.

In a study involving 176 males attending an infertility clinic and 88 controls awaiting elective vasectomy, the semen acid phosphatase activity was found to be significantly higher in the former group (p less than 0.001). However, no definite relationship of semen acid phosphatase level to ejaculate volume, sperm motility, viability, morphology, seminal zinc, magnesium or fructose was observed in either group. The distribution of acid phosphatase in the males attending the infertility clinic, unlike that of the controls, was found to be bimodal. 32 presumably infertile males had acid phosphatase values exceeding the control mean +/- 2 SD. These 32 nevertheless did not have a significantly different mean ejaculate volume, sperm motility, morphology or viability, when compared with the group with normal acid phosphatase levels. Causes of the bimodal distribution of concentrations of acid phosphatase are discussed.

Acid Phosphatase↗
PubMed1986

Experimental nude mouse model of human colorectal cancer liver metastases.

A nude mouse model (BALB/c) was established for investigating the production of hepatic metastases by human colorectal carcinoma (HCC) cells. The malignant potentials of 3 different HCCs derived from a primary tumor (HCC-P4733), a lymph node metastasis (HCC-M14328), and a hepatic metastasis (HCC-M1410) were investigated following implantation into the spleens of athymic nude mice. Cells of the HCC-M1410 line produced extensive liver tumors in all mice by 30 days after injection. Cells of the HCC-M14328 and HCC-P4733 lines produced few liver tumors in the inoculated mice and then only after a 90-day period. Isozyme and karyotype analyses ascertained the human origin of all the tumors. Studies with [125I]IdUrd-labeled HT-29 carcinoma cells suggested that tumor cells reached the liver shortly after injection into the spleen. Thus the production of HCC tumors in livers of nude mice was determined by the ability of HCC cells to proliferate in the liver parenchyma rather than by the ability of the cells to reach the liver. The results suggest that the intrasplenic injection of HCC cells can provide a valuable model for the study of the biology and therapy of the liver metastases.

Animals↗
PubMed1985

Coronary arteritis in mice following the systemic injection of group B Lactobacillus casei cell walls in aqueous suspension.

We describe the induction of an asymmetric, focal, inflammatory coronary arteritis by a single intraperitoneal injection of group B Lactobacillus casei cell wall fragments in various inbred mouse strains. This coronary arteritis resembles the arteritis which is responsible for the 1-2% fatality rate among children with mucocutaneous lymph node syndrome. Coronary arteritis developed in 18 of 26 C57BL/6, 14 of 26 A/J, 7 of 15 Balb/c, and 8 of 15 C3Heb/FeJ mice injected. It also developed in 2 of 4 "nude" A/J background mice and 3 of 4 "nude" C57BL/6 mice, but in 0 of 15 C3H/HeJ mice. Lesions were evident as early as 3 days following injection. The development of arteritis was accompanied by disruption of the arterial intima and media with true aneurysm formation. Measurement of serial IgG and IgM titers indicated no relationship between the development of coronary arteritis and immunoglobulin response to L casei cell walls or the development of antibodies cross-reactive with normal myocardium. The absence of disease in only the C3H/HeJ mice, which are known to have defective macrophages, suggests that macrophages may play an essential role in the pathogenesis of coronary arteritis.

Animals↗
PubMed1985

Abrogation of macrophage-mediated suppression of T-lymphocyte proliferation with hemoglobin and hemin is a function of iron content.

Hemoglobin, hemin, and ferric ion (Fe) were shown to reverse peritoneal exudate cell (PEC)-mediated suppression of concanavalin A-elicited murine spleen cell activation. Titration of hemoglobin and hemin relative to Fe showed a direct relationship between Fe content and reversal of PEC suppression. Indomethacin enhanced the capacity of all three compounds to abrogate PEC suppression on the order of five- to eight-fold. The capacity of endogenous Fe-containing substances as hemoglobin and its catabolites, e.g., hemin, to modulate macrophage expression may be of special significance at sites of inflammation.

Animals↗
PubMed1985

Primed lymphoid cell tolerance. II. In vivo tolerization of highly tolerogen-sensitive hapten-primed, potentially IgG-producing B cells.

The relative ease of tolerizing IgM-bearing versus IgG-bearing B cells was investigated. Previous work had shown that IgG-bearing trinitrophenyl (TNP)-specific B cells from mice primed and boosted with TNP-keyhole limpet hemocyanin (TNP-KLH) are highly susceptible to tolerization in vitro by TNP presented on an unrelated carrier. TNP-OVA was used as tolerogen, as it may represent a more general class of tolerogens than those which are nonmetabolizable or immunoglobulin containing. This study showed that highly primed B cells are tolerizable in vivo using TNP-OVA, with the IgG response to TNP-KLH easier to tolerize than the IgM response. To determine if the ease of tolerization of the IgG response in vivo was due to intrinsic differences in B-cell precursors of the IgM and IgG responses, tolerance was performed in vitro with B cells of defined surface isotypes. A T-independent antigen, TNP-endotoxin, was employed to minimize T-cell effects. At least 10 times as much TNP-OVA was required to tolerize B cells bearing the IgM surface isotype than those with the IgG surface isotype. Thus, the ease of inhibition of the IgG response as compared to the IgM response in vivo by preexposure to TNP-OVA may be at least partially explained by inherent differences in IgM and IgG B-cell precursors.

Animals↗
PubMed1985

Characterization of profiles of salivary progesterone concentrations during the luteal phase of fertile and subfertile women.

Salivary progesterone concentrations were measured in daily samples collected between 08.00 and 09.00 h throughout the menstrual cycle of women with a history of fertility. The luteal-phase salivary progesterone profiles in these normally menstruating, healthy women were characterized using a computer program based on a cumulative sum procedure. This method of statistical analysis led to the development of a 'progesterone boundary diagram', the inner and outer domains of which distinguished between the profiles of salivary progesterone considered compatible with fertility, and those observed in subfertile women attending an infertility clinic.

Adolescent↗
PubMed1984

Interference with tolerance induction of primed B cells by the Fc fragment of immunoglobulin.

The capacity to interfere with tolerance induction in primed B cells was examined. Previous work had shown that TNP-specific splenic B cells from mice primed and boosted with TNP-KLH are highly susceptible to in vitro tolerization upon a brief exposure to TNP on a carrier unrelated to KLH. In the present work it was found that tolerance induction in these primed B cells could be partially disrupted by addition of the Fc fragment of immunoglobulin, a B-cell mitogen, and adjuvant, during exposure of the B cells to tolerogen. Addition of Fc fragments prepared by papain digestion of human IgG interfered with tolerization routinely in approximately 30-60% of the spleen cells susceptible to tolerogen. Addition of whole IgG or Fab fragments had no effect on tolerance induction. As little as 5 micrograms/ml of the Fc fragment preparation significantly interfered with tolerization and 32-64 micrograms/ml was optimal. Disruption of tolerization was most effective when the Fc fragment was added to the spleen cells either 4 hr prior to tolerogen or simultaneously with tolerogen; addition of the Fc fragment 4 hr after exposure to tolerogen was significantly less effective. Disruption of tolerization by the Fc fragment was not through polyclonal activation of B cells, as antigen was required for generation of significant numbers of PFC to TNP. Also, disruption was not through expansion of low avidity clones of B cells insusceptible to tolerogen, as the avidity of the antibody produced with and without Fc fragments present was approximately the same. These results show that the Fc fragment of IgG can partially interfere with tolerization of primed B cells. The manner in which Fc fragments may function to prevent tolerization through its lymphoid cell stimulatory capacities is discussed.

Animals↗
PubMed1984

The effect of Ureaplasma urealyticum on semen characteristics.

Semen samples from 280 men were cultured for Ureaplasma. The presence of Ureaplasma in the male genital tract did not affect ejaculate volume, motility, viability, or morphology. Sperm concentration was significantly lower in the presence than in the absence of Ureaplasma. The longevity of sperm as evaluated by sperm motility and viability at different intervals of time was also not influenced by the presence of Ureaplasma. Biochemical parameters, namely zinc, magnesium, acid phosphatase, and fructose were not affected by the presence of Ureaplasma. No relationship of Ureaplasma with sperm antibodies, aerobic infection, or anaerobic infection was observed.

Acid Phosphatase↗