Comparison of immunoscintigraphy and computerized tomography in identifying colorectal cancer: individual lesion analysis

Monoclonal antibody scintigraphy with 111In-ZCE025 was used in presurgical staging of 45 patients prior to abdominal exploration for primary, recurrent or metastatic colorectal carcinoma. A total of 186 lesions were identified, of which 147 were evaluated by abdominal surgery and pathology. Sensitivity was 40.5% (49 of 121) for immunoscintigraphy (IS), 61.2% (74 of 121) for computerized tomography (CT), and 72.7% (88 of 121) for IS and CT combined. The positive predictive value was 83.1% (49 of 59) for IS and 88.1% (74 of 84) for CT. Sensitivity of IS was 100% (23 of 23) for primary tumors, 17.7% (11 of 62) for hepatic metastases, and 41.7% (15 of 36) for extrahepatic abdominal metastases. Of the 50 hepatic lesions evaluated by single-proton emission computerized tomography, 11 were localized by IS. Only one was visualized by planar scintigraphy. Sensitivity of CT was 87% (20 of 23) for primary tumors, 67.7% (42 of 62) for hepatic metastases, and 33.3% (12 of 36) for extrahepatic abdominal metastases. Sensitivity of IS combined with CT was 72.6% (45 of 62) for hepatic and 55.6% (20 of 36) for extrahepatic abdominal metastases. Of 24 malignant lesions measured by the pathologist to be less than 3.0 cm (maximum dimension), 7 (29.2%) were detected by IS and 3 (12.5%) by CT. Of 28 malignant lesions greater than 3.0 cm, 23 (82.1%) were detected by IS and 24 (85.7%) by CT. Overall, IS and CT complemented each other in presurgical staging of colorectal carcinoma. IS was of greater value for identification of extrahepatic and small metastases. CT was more effective for identification of hepatic metastases.

Interferon enhancement of radioimmunotherapy for colon carcinoma

Recombinant human gamma-interferon (IFN-gamma) has recently been shown to enhance localization of radiolabeled monoclonal antibodies (MAb) to human colon carcinoma xenografts in athymic mice. The present study investigates the ability of gamma-interferon to enhance radioimmunotherapy of a low carcinoembryonic antigen-expressing human colon cancer (WiDr) in athymic mice. Growth curve analysis, antibody localization, and dose estimation studies were performed. A significant tumor growth delay, measured as the time to reach 1.0 g, was noted for animals receiving specific anti-carcinoembryonic antigen 90Y-MAb (ZCE025, 120 microCi) plus IFN-gamma (61.8 days) as compared to animals that received specific 90Y-MAb with phosphate-buffered saline (34.9 days; P less than 0.005). IFN-gamma (100,000 units) was given i.p. every 8 h for 2 days before and 4 days after 90Y-MAb therapy. The time required to reach 1.0 g for animals treated with nonspecific 90Y-MAb (ZME018) was significantly less either with (38.3 days) or without (34.4 days) IFN-gamma. The difference was more apparent when compared to animals receiving IFN-gamma alone (30.0 days) or phosphate-buffered saline alone (28.9 days; P less than 0.001). Increased antibody localization in the tumors of animals treated with IFN-gamma plus specific 90Y-MAb (43.2% injected dose/g) was seen in comparison to animals treated with specific 90Y-MAb without IFN-gamma (18.2% injected dose/g). The estimate of radiation dose delivered to the tumors, based on biodistribution data over time, revealed significantly higher levels in animals treated with specific 90Y-MAb with IFN-gamma (2477 cGy) compared to animals treated without IFN-gamma (1217 cGy). These results provide support for the use of gamma-interferon as an immunomodulating agent prior to radioimmunotherapy.

A transition metal complex (Venus flytrap cluster) for radioimmunodetection and radioimmunotherapy

A novel transition metal complex, Venus flytrap cluster (VFC), is described for the preparation of radio-labeled antibodies. VFC contained 57Co, which was held tightly between the faces of two covalently bridged carborane ligands by cluster bonding of the metal with appropriate ligand orbitals. Anti-carcinoembryonic antigen monoclonal antibody T84.66 was conjugated to 57Co-VFC with full retention of immunological activity. Biodistribution studies in nude mice bearing carcinoembryonic antigen-producing tumors showed excellent tumor localization of 57Co-VFC-T84.66. The accumulation of radionuclide in normal liver was low and independent of dose, which may reflect the stability of the radionuclide complex. These results presage the use of VFC systems for binding transition metals that are clinically useful for radioimmunodiagnosis and radioimmunotherapy.

Radiobiologic studies comparing Yttrium-90 irradiation and external beam irradiation in vitro

The purpose of this study was to compare the effectiveness of Yttrium-90 (Y-90) labeled antibody irradiation to 60Co external beam irradiation in vitro by colony formation assay. Two human colon carcinoma cell lines, LS174T, a high CEA producer, and WiDr, a low CEA producer, were exposed to specific activities of Y-90 labeled murine monoclonal anti-CEA antibody ranging from 2.5 to 30 microCi/ml for a fixed period of time. This resulted in calculated doses of 2.25 to 27 Gy and initial dose rates of 2.5 to 29 cGy/hr. Results were compared to similar doses of Y-90 labeled non-specific antibody, unlabeled specific and non-specific antibody, and 60Co external beam irradiation. External beam irradiation studies showed that WiDr, compared to LS174T, was more radioresistant with a larger shoulder to the survival curve, indicating a greater capacity for radiation-induced sublethal damage repair. WiDr was also more radioresistant to Y-90 antibody irradiation. When compared to external beam irradiation, Y-90 labeled antibody irradiation resulted in less cell killing by a factor of 2.4 for LS174T and 3.4 for WiDr. Unlabeled antibody had no significant effect on cell survival. Radiation-induced cell cycle delay experiments demonstrated that WiDr had less cell cycle delay (0.9 to 1.0 min/cGy) compared to LS174T (1.2 min/cGy) after single fraction external beam irradiation. Our results indicate that Y-90 low dose-rate irradiation is radiobiologically less effective in vitro than high dose-rate external beam irradiation by a factor of about 2.4 to 3.4. The results also suggest that the magnitude of this difference depends on the cell line's ability to repair sublethal radiation damage and the degree of cell cycle prolongation after irradiation.

Mating-related estradiol fluctuations during the estrous cycle of the Bolivian squirrel monkey (Saimiri boliviensis boliviensis)

The female squirrel monkey, Saimiri boliviensis, a New World monkey, has 10-day estrous cycles during the annual breeding season. Measurements of serum estradiol (E) concentrations in females housed with males in breeding pens revealed markedly higher levels than previously reported. Additionally, females in breeding pens appeared to have two distinct patterns of serum E peaks relative to the LH surge. Serum estrogen peaks averaging 5-fold greater than levels on the preceding day were observed on the same day as the LH surge, whereas other females had only a small E rise on the day of the LH surge followed by a 6-fold E rise on the next day. The serum progesterone (P) levels in all animals were depressed for 1-2 days before the LH surge but frequently started to rise on the day of the LH surge. The effect of the presence of a breeding male was examined by studying females housed in a group pen without exposure to a breeding male. In contrast to breeding-pen patterns, relatively small E rises were found in the 10 cycles observed. To further elucidate estrus-related E rises, a limited male-access paradigm was used to isolate mating-related hormone fluctuations. Pre-mating E levels had no marked rises; however, 4 h after mating, whether on the day of the LH surge or the next day, large E rises were found. These studies indicate that the LH surge in cycling squirrel monkeys is consistently preceded by a marked P nadir and associated with relatively small E rises.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of different atmospheric ozone partial pressures on photosynthesis and growth of nine fruit and nut tree species

Nursery stock of peach (Prunus persica L. Batsch, cv. O'Henry), nectarine (P. persica L. Batsch, cv. Fantasia), plum (P. salicina Lindel., cv. Casselman), apricot (P. armeniaca L., cv. Tilton), almond (P. dulcis Mill., cv. Nonpareil), prune (P. domestica L., cv. Improved French), cherry (P. avium L., cv. Bing), oriental pear (Pyrus pyrifolia Rehd., cv. 20th Century), and apple (Malus pumula Mill., cv. Granny Smith) were planted in open-top chambers on April 1, 1988 at the University of California's Kearney Agricultural Center located in the San Joaquin Valley (30 degrees 40' N 119 degrees 40' W). Trees were exposed to three atmospheric ozone partial pressures (charcoal-filtered air (C), ambient air (A), or ambient air + ozone (T)) from August 1 to November 17, 1988. The mean 12-h (0800 to 2000 h) ozone partial pressures measured in open-top chambers during the experimental period were 0.030, 0.051, and 0.117 microPa Pa(-1) in the C, A and T treatments, respectively. Leaf net CO(2) assimilation rate decreased linearly with increasing 12-h mean ozone partial pressure for the almond, plum, apricot, prune, pear, and apple cultivars. Stomatal conductances of apricot, apple, almond, and plum decreased linearly with increasing ozone partial pressure. Cross-sectional area relative growth rates of almond, plum, apricot, and pear decreased linearly with increasing ozone partial pressure. Net CO(2) assimilation rate, stomatal conductance, and trunk growth of cherry, peach and nectarine were unaffected by the ozone treatments. Reduced leaf gas exchange probably contributed to ozone-induced growth reduction of the susceptible species and cultivars. Several of the commercial fruit tree species and cultivars studied were relatively tolerant to the ozone treatments.

Characterization of solute transport in plasma membrane vesicles isolated from cotyledons ofRicinus communis L. : I. Adenosine triphosphatase and pyrophosphatase activities associated with a plasma membrane fraction isolated by phase partitioning

A highly enriched plasma membrane fraction has been isolated from dark-grown cotyledons ofRicinus communis by phase partitioning. This is demonstrated by the properties of the associated ATPase: high vanadate sensitivity, azide and nitrate insensitivity, sharp pH optimum around 6.5, and high specificity for ATP as substrate. The upper plasma membrane fraction also contained a pyrophosphatase activity, normally considered to be located on the tonoplast or Golgi membranes, which showed a specific activity higher than that in the lower phase. Sucrose gradient centrifugation of both microsomal and upper phase fractions showed a comigration of some pyrophosphatase activity with the plasma membrane fraction. Sucrose uptake changes with development inRicinus cotyledons. The ATPase activity in the upper (plasma membrane) phase also varied in a similar way with development, whereas activity in the lower phase showed little change. Pyrophosphatase activity in the upper phase also increased with development but did not show a peak and fall as seen for sucrose uptake and ATPase. The possibility that changes in plasma membrane ATPase may contribute to changes in sucrose uptake capacity and the possible cellular origin and physiological significance of the pyrophosphatase activity are discussed.

Characterization of solute transport in plasma membrane vesicles isolated from cotyledons ofRicinus communis L. : II. Evidence for a proton-coupled mechanism for sucrose and amino acid uptake

Evidence is presented for the proton-coupled transport of sucrose and glutamine in purified plasma membrane vesicles isolated from cotyledons ofRicinus communis. Imposition of a pH gradient (internal alkaline) across the plasma membrane resulted in a rapid uptake of sucrose and glutamine which was inhibited in the presence of carbonyl cyanide-m-chlorophenyl hydrazone. Imposition of a pH gradient plus an internal negative membrane potential stimulated uptake further. Glucose and fructose uptakes were negligible under these conditions. Sucrose uptake into the vesicles demonstrated saturation kinetics with a Km of 0.87 mol·m(-3), indicating carrier-mediated transport. In support of this, uptake was very sensitive to the protein-modifying reagentp-chloromercuribenzenesulphonic acid. N-Ethylmaleimide, another sulphydryl reagent, was only slightly inhibitory. However, both reagents strongly inhibited sucrose uptake into intact cotyledons; the possible reasons for the difference between the intact and isolated systems are assessed. The value of this system for the study of sucrose and amino acid carriers is discussed.

Preliminary report: imaging of Kaposi sarcoma and lymphoma in AIDS with indium-111-labelled liposomes

Kaposi sarcoma and malignant lymphoma were successfully imaged with high purity liposomes containing indium-111 in two patients with AIDS. Gamma camera images of the patient with Kaposi sarcoma showed four discrete lesions along the left foot and calf with no foci along the right foot, and no uptake into clinically enlarged but non-neoplastic lymph nodes. The spread of the Kaposi sarcoma was proximal along the leg. The neoplastic cervical lymph nodes in the second patient who had large-cell diffuse intermediate grade lymphoma were also imaged successfully. Since Kaposi sarcoma and lymphoma frequently involve occult sites, liposome imaging may prove useful in the diagnosis and management of these diseases.

Localization of intraperitoneal xenografts of human colon cancer by radiolabeled anti-CEA antibodies

An intraperitoneal xenograft tumor model was developed in the nude mouse to represent advanced colorectal disease in the human patient. Intraperitoneal (ip) and subcutaneous (sc) tumor xenografts were successfully localized by indium 111-labeled anti-carcinoembryonic antigen monoclonal antibodies (Indacea) administered intravenously (IV) or intraperitoneally (IP). In the sc model, tumor uptake (% injected dose per g of tumor tissue--%ID/g) was significantly improved at 72 hours postinjection when Indacea was administered IP (44.01 +/- 1.94 vs. 33.74 +/- 0.87, P less than 0.005). In the ip model, tumor uptake at 72 hours was improved with IP Indacea (28.23 +/- 5.42 vs. 19.36 +/- 5.50, P less than 0.01) and the tumor to blood ratio was significantly improved for IP Indacea (17.83 +/- 2.95 vs. 8.45 +/- 1.38, P less than 0.01). Tumor mass was not a contributing factor in these differences. This study demonstrates that ip xenografts can be successfully imaged using radiolabeled antibodies and that the IP route of administration results in better tumor uptake of the antibody in ip lesions.

Hypoglycemia of squirrel monkey neonates: implications for infant survival

Neonatal deaths are a serious problem in breeding colonies of squirrel monkeys. Seriously ill neonates in our colony are always hypoglycemic on presentation. To determine normal glucose values for squirrel monkey infants of various ages, serum glucose determinations were done at 1, 3, 7, 10, 14 days and 1 month of age using a standard laboratory test for serum glucose. Glucose concentration increased from a low of 49 +/- 3 mg/dl (Mean +/- SEM) at 1 day (n = 21) to 109 +/- 4 mg/dl at 1 month of age (n = 17). Glucose values for 1, 3 and 7 day-old infants were significantly lower than 1 month-old infants (P less than .05). To provide a time-averaged indication of blood glucose, glycosylated hemoglobin (GHb) measurements were made at 1 day, 1 week, 2 weeks, 1 month, 2 months, 1 year of age and in adults (greater than 3 years of age). GHb values ranged from 2.6% +/- 0.1 for 1 day old infants (n = 13) to 4.0 +/- 0.2 for adults (n = 10) with a steady increase during the first 2 months of life. Animals 1 year of age and younger had significantly lower glycosylated hemoglobin than adults. These studies indicate that blood glucose concentration is significantly lower in squirrel monkey neonates than in older infants, juveniles and adults. Maternal rejection, trauma, and associated problems occur commonly in socially reared squirrel monkeys. The marginal hypoglycemic state of these infants places them at high risk for clinical hypoglycemia as a sequel to such perturbations.

Radioimmunotherapy of human colon cancer in nude mice

Nude mice bearing subcutaneous human colon cancer xenografts (LS174T) were treated with 120 microCi of yttrium 90-labeled anti-carcinoembryonic antigen monoclonal antibodies (specific therapy), 120 microCi of 90Y-labeled anti-melanoma monoclonal antibodies (nonspecific therapy), or phosphate-buffered saline solution (no treatment control). Mean (+/- SD) tumor growth rates (percent increase per day) over the first 30 days of the study were as follows: 0.6% +/- 0.2% per day (specific therapy); 17.7% +/- 5.7% per day (nonspecific therapy); and 30.5% +/- 4.2% per day (control). In all three groups, tumors over 1 g had similar doubling times (5.74 +/- 0.71 d). Specific therapy caused a lag in tumor growth corresponding to a 3-logarithm cell kill. Estimated tumor dose of radiation obtained by tissue analysis was 34 and 14 Gy for specific and nonspecific therapy, respectively. In conclusion, 120 microCi of 90Y-labeled anti-carcinoembryonic antigen monoclonal antibodies was effective in suppressing growth of human colon cancer xenografts. Clinical studies with this preparation are recommended.

Further Characterization of the Red Beet Plasma Membrane Ca-ATPase Using GTP as an Alternative Substrate

The GTP-driven component of Ca(2+) uptake in red beet (Beta vulgaris L.) plasma membrane vesicles was further characterized to confirm its association with the plasma membrane Ca(2+)-translocating ATPase and assess its utility as a probe for this transport system. Uptake of (45)Ca(2+) in the presence of GTP demonstrated similar properties to those previously observed for red beet plasma membrane vesicles utilizing ATP with respect to pH optimum, sensitivity to orthovanadate, dependence on Mg:substrate concentration and dependence on Ca(2+) concentration. Calcium uptake in the presence of GTP was also strongly inhibited by erythrosin B, a potent inhibitor of the plant plasma membrane Ca(2+)-ATPase. Furthermore, after treatment with EGTA to remove endogenous calmodulin, the stimulation of (45)Ca(2+)-uptake by exogenous calmodulin was nearly equivalent in the presence of either ATP or GTP. Taken together these results support the proposal that GTP-driven (45)Ca(2+) uptake represents the capacity of the plasma membrane Ca(2+)-translocating ATPase to utilize this nucleoside triphosphate as an alternative substrate. When plasma membrane vesicles were phosphorylated with [gamma-(32)P]-GTP, a rapidly turning over, 100 kilodalton phosphorylated peptide was observed which contained an acyl-phosphate linkage. While it is proposed that this peptide could represent the catalytic subunit of the plasma membrane Ca(2+)-ATPase, it is noted that this molecular weight is considerably lower than the 140 kilodalton size generally observed for plasma membrane Ca(2+)-ATPases present in animal cells.

Biochemical genetic markers of squirrel monkeys and their use for pedigree validation

Family data for 14 biochemical genetic markers fo squirrel monkeys (genus Saimiri) were derived from 73 pedigreed progeny and both parents of each, as well as from 16 additional progeny and one parent of each. The data for each marker and the phenotypic patterns were consistent with autosomal codominant inheritance. It was concluded from the genetic marker data that the pedigree records of seven progeny were incorrect. Retrospective investigations of colony records followed by typing of animals that might possibly have been a parent enabled five of the pedigree records to be corrected. Although five of the pedigree errors were cases of mistaken paternity, the other two apparently were the consequence of infant swapping between dams shortly after birth. Because squirrel monkeys exhibit a high degree of allomaternal behavior, infant swapping between dams may occur more frequently than in many other nonhuman primate species.

Presurgical imaging with indium-labeled anti-carcinoembryonic antigen for colon cancer staging

Over a 4-year period, 108 patients with known or suspected colorectal cancer were studied by radioimmunoconjugate scintigraphy prior to operative procedures. Study subjects received 0.2 to 40 mg i.v. of murine anti-carcinoembryonic antigen monoclonal antibody labeled with 2-5 mCi of 111In (Indacea). Resected tissues were analyzed for 111In and carcinoembryonic antigen content. Tumor, liver, and draining lymph nodes had over 10% injected dose/kg compared to less than 2.5% injected dose/kg for other normal tissues. Primary tumors that were successfully imaged were significantly larger and had higher 111In and carcinoembryonic antigen content. In 54 patients, primary tumors were visualized with a sensitivity of 78%. Hepatic metastases (58 patients) were visualized as negative filling defects (sensitivity, 45%). Extrahepatic (intraabdominal) metastases (25 patients) were visualized (sensitivity, 48%) as areas of increased uptake. Extraabdominal metastases were uncommon (10 patients; sensitivity, 80%). Of 56 patients with known or suspected hepatic metastases who presented with no evidence of extrahepatic disease by conventional tests (X-ray, computerized tomographic scan), 20 (36%) were documented to have extrahepatic metastases at exploratory surgery and 10 of these (50%) had the extrahepatic disease localized by the Indacea scan. The management of these 10 patients was, or could have been, modified by the scan findings and unnecessary surgery eliminated.

Estimation of monoclonal antibody-associated 90Y activity needed to achieve certain tumor radiation doses in colorectal cancer patients

In these measurements, we quantitated, via surgical samples, human primary tumor uptake of the anti-carcinoembryonic antigen monoclonal antibody T84.66. Uptake was measured in units of percentage of injected dose/kg with 111In as the radiolabel. All 11 colorectal lesions were nonnecrotic and were visualized upon scanning. Tumor volume was calculated using the three orthogonal dimensions as described by pathology. Uptake mean +/- SD was 6.55 +/- 3.55% injected dose/kg with a range of 1.2 to 10.4% injected dose/kg. Lesion mean volume was 36 cm3 with a range of 1.5 to 304 cm3. Using mean values, assuming no biological clearance and that the biodistribution of the monoclonal is independent of its radiolabel, the predicted human tumor 90Y beta dose was 0.12 Gy/mCi. Therefore a 10-Gy tumor dose would require 83 mCi of i.v. activity. Using least and highest uptake results, requisite activity values were 3-fold larger and smaller respectively. Thus, there was approximately an order of magnitude variation in the amount of 90Y predicted to achieve a given tumor dose in colorectal cancer patients. Murine and human uptake values were consistent if lesion mass and carcinoembryonic antigen content were taken into account.

Effects of Ambient and Acute Partial Pressures of Ozone on Leaf Net CO(2) Assimilation of Field-Grown Vitis vinifera L

Mature, field-grown Vitis vinifera L. grapevines grown in open-top chambers were exposed to either charcoal-filtered air or ambient ozone partial pressures throughout the growing season. Individual leaves also were exposed to ozone partial pressures of 0.2, 0.4, or 0.6 micropascals per pascal for 5 hours. No visual ozone damage was found on leaves exposed to any of the treatments. Chronic exposure to ambient O(3) partial pressures reduced net CO(2) assimilation rate (A) between 5 and 13% at various times throughout the season when compared to the filtered treatment. Exposure of leaves to 0.2 micropascals per pascal O(3) for 5 hours had no significant effect on A; however, A was reduced 84% for leaves exposed to 0.6 micropascals per pascal O(3) when compared to the controls after 5 hours. Intercellular CO(2) partial pressure (c(i)) was lower for leaves exposed to 0.2 micropascals per pascal O(3) when compared to the controls, while c(i) of the leaves treated with 0.6 micropascals per pascal of 0(3) increased during the fumigation. The long-term effects of ambient O(3) and short-term exposure to acute levels of O(3) reduced grape leaf photosynthesis due to a reduction in both stomatal and mesophyll conductances.

The effects of hyperthermia on tumor carcinoembryonic antigen expression

The effects of hyperthermia on carcinoembryonic antigen (CEA) expression were investigated. The human colon adenocarcinoma cell line, LS174T, was heated in vitro for 42 degrees C/1 hr, 43 degrees C/1 hr, or 45 degrees C/30 min. Carcinoembryonic antigen membrane expression was assayed by live cell radioimmunoassay 0-6 days after heating. A heat exposure of 45 degrees C/30 min resulted in an initial decrease in carcinoembryonic antigen membrane expression 1 day post-heating followed by a 2-3 fold increase which peaked 3 days post-heating. Carcinoembryonic antigen expression began returning to normal by the sixth day. Heat exposures of 42 degrees C/1 hr and 43 degrees C/1 hr also resulted in increased carcinoembryonic antigen expression but this increase was of lesser magnitude and of shorter duration. Carcinoembryonic antigen shed into the medium, as measured by enzyme immunoassay, also increased after heating in a temperature-dependent fashion. Flow cytometry analysis demonstrated that cells in all phases of the cell cycle expressed this increase. We conclude that hyperthermia results in significant changes in carcinoembryonic antigen membrane expression and shedding. The implications that these findings have with regards to clinical hyperthermia and radioimmunotherapy are discussed.

Measurement and estimation of organ Bremsstrahlung radiation dose

Bremsstrahlung radiation doses were measured in an anthropomorphic phantom using thermoluminescent dosimeters. A single source of 90Y (beta-ray range less than or equal to 1.0 cm) was inserted in the bladder region and dosimeters were placed at distances greater than or equal to 3 cm to preclude detection of decay betas. Doses were corrected so as to represent the case of no biologic clearance. By comparing dosimeter location with the standard MIRD human geometry, sample organ doses could be determined. Representative results were 432 +/- 76 mrad/mCi at 3 cm (bladder), 260 +/- 60 mrad/mCi (uterus), 71 +/- 4 mrad/mCi (lower large intestine), and 1.4 +/- 0.7 mrad/mCi (liver). An estimation method, based on absorbed fraction tables, gave organ doses that were within the errors of measurement for all tissues with the exception of the bladder site. We conclude that organ bremsstrahlung radiation doses are not negligible and that they can be estimated using an integration over both the brake and beta-ray spectra.

Net CO(2) Assimilation and Carbohydrate Partitioning of Grapevine Leaves in Response to Trunk Girdling and Gibberellic Acid Application

Leaf net CO(2) assimilation rate (A), stomatal conductance (g(s)), carboxylation efficiency, and foliar nonstructural carbohydrates were measured on mature, field-grown Vitis vinifera L. (cv Thompson Seedless) vines that had been trunk girdled, sprayed with gibberellic acid, or both, shortly after anthesis. Girdling reduced A, g(s), and carboxylation efficiency when measured 2 weeks after imposition of the treatments. Diurnal measurements indicated that A of girdled vines was less than that of control vines between 1000 and 1800 hours. Gibberellic acid mitigated the depressing effect of girdling on g(s) during the same diurnal measurements. The concentrations of foliar carbohydrates were greatest for the girdled vines, followed by the combination treatment and were lowest for the control vines. Foliar carbohydrates were greater for girdled vines 4 weeks after the treatments were imposed, however, by this time there was no significant difference in A between the control and girdled vines. Two and 4 weeks after the experiment was initiated root carbohydrate concentrations were less for the girdled vines when compared to the control vines. The data indicate that the reduction in A of girdled grapevines is not associated with the accumulation of leaf nonstructural carbohydrates following the girdling treatment.

Effect of specific antibody pretreatment on liver uptake of 111In-labeled anticarcinoembryonic antigen monoclonal antibody in nude mice bearing human colon cancer xenografts

Administration of a large dose (0.2 mg) of unlabeled specific anticarcinoembryonic antigen (anti-CEA) monoclonal antibody (MAB) to nude mice bearing LS174T human colon cancer xenografts significantly decreased normal liver uptake of 111In-labeled anti-CEA MAB (Indacea). Mice bearing tumors of approximately 1 g showed liver accumulation of indium-111 at 48 h following injection of 2 micrograms/10 microCi Indacea of 33.8 +/- 1.5% injected dose per gram (%ID/g) (N = 25). Treatment with 0.2 mg unlabeled anti-CEA MAB reduced this to 8.9 +/- 0.5% ID/g (N = 22; P less than 0.001). The dose of pretreatment was found to be critical. Increasing the amount of unlabeled MAB to 2.0 mg did not significantly improve the liver level of indium-111, but did compromise the tumor uptake of Indacea (15.9 +/- 1.3 versus 12.4 +/- 0.4% ID/g; P less than 0.05). Lowering the dose of pretreatment 10-fold resulted in increased (P less than 0.001) liver uptake of the label (26.5 +/- 2.8% ID/g). The unlabeled anti-CEA MAB treatment given as a single dose or fractionated over several days gave the same results. The decrease in liver uptake was the same for i.v. administration of the unlabeled MAB given 1 week prior to Indacea injection or mixed together with Indacea. With i.p. administration, simultaneous injection of the unlabeled MAB with Indacea was not as effective as pretreatment (20 min to 7 days) in decreasing the liver uptake of 111In (P less than 0.05). Epitope specificity and affinity were shown to be important considerations in the choice of MAB combinations used for pretreatment and imaging. Pretreatment with nonspecific MAB was ineffective in decreasing liver uptake of Indacea.

The effects of tumor mass, tumor age, and external beam radiation on tumor-specific antibody uptake

The effects of external beam radiation on tumor uptake of radiolabeled monoclonal antibody were investigated. Nude mice bearing carcinoembryonic antigen (CEA)-producing subcutaneous human tumor xenografts (LS174T) were irradiated (60Co) with a single fraction of 0, 2 or 20 Gy, 6 or 11 days after tumor inoculation. An Indium-111 labeled anti-CEA monoclonal antibody (T84.66) was injected 1-2 hrs after irradiation. Biodistribution studies performed at 48 hrs showed a statistically significant (p less than 0.01) inverse correlation between tumor mass and tumor antibody uptake. Tumor age was also a significant factor with 11 day old tumors having significantly less uptake (p less than 0.0001) compared to 6 day old tumors for a given mass. Radiation increased tumor antibody uptake only in those tumors where growth inhibition also occurred. Multiple regression analysis showed that this inverse correlation between tumor mass and antibody uptake was the same for irradiated and nonirradiated tumors. We conclude that, in this model system, radiation does not act independently to enhance tumor antibody deposition. Radiation's primary effect is to reduce tumor mass, with mass reduction then resulting in an increase in antibody uptake. The clinical implications of this study are discussed.

Determination of lactogenic activity in the serum of the squirrel monkey (Saimiri boliviensis) using the Nb2 lymphoma bioassay

Determination of squirrel monkey prolactin by immunoassay has been hampered by the lack of antiserum specific to prolactin from this species. As an alternate method, we have investigated whether the Nb2 lymphoma bioassay could be adapted for routine measurement of the lactogenic activity of samples of squirrel monkey serum. The growth of the Nb2 cells is absolutely dependent on the presence of lactogens in the culture medium. The cells were maintained in Fisher's medium supplemented with 10% horse serum, 10% fetal calf serum (FCS), and 10^-4M β-mercaptoethanol. For each assay, the cells were plated at an initial density of 1 × 10⁵ cells/ml in 22-mm 12-well dishes in the above medium, but devoid of FCS. Serum samples were heated to 56°C for 20 minutes to abolish the unusually high cytolytic complement activity of squirrel monkey serum and were incubated for 72 hours with Nb2 cells at serial dilutions from 1/40 to 1/2,560. Growth curves were generated with pooled samples of squirrel monkey serum, and the level of lactogenic activity was estimated using a calibration growth curve generated with known concentrations of purified rhesus monkey prolactin standard. We have found that the Nb2 lymphoma bioassay provides a sensitive and adaptable means for determination of lactogenic activity in the serum of the squirrel monkey.