Early Cancer Detection in Li-Fraumeni Syndrome with Cell-Free DNA

People with Li-Fraumeni syndrome (LFS) harbor a germline pathogenic variant in the TP53 tumor suppressor gene, face a near 100% lifetime risk of cancer, and routinely undergo intensive surveillance protocols. Liquid biopsy has become an attractive tool for a range of clinical applications, including early cancer detection. Here, we provide a proof-of-principle for a multimodal liquid biopsy assay that integrates a targeted gene panel, shallow whole-genome, and cell-free methylated DNA immunoprecipitation sequencing for the early detection of cancer in a longitudinal cohort of 89 LFS patients. Multimodal analysis increased our detection rate in patients with an active cancer diagnosis over uni-modal analysis and was able to detect cancer-associated signal(s) in carriers prior to diagnosis with conventional screening (positive predictive value = 67.6%, negative predictive value = 96.5%). Although adoption of liquid biopsy into current surveillance will require further clinical validation, this study provides a framework for individuals with LFS.

SIGNIFICANCE

By utilizing an integrated cell-free DNA approach, liquid biopsy shows earlier detection of cancer in patients with LFS compared with current clinical surveillance methods such as imaging. Liquid biopsy provides improved accessibility and sensitivity, complementing current clinical surveillance methods to provide better care for these patients. See related commentary by Latham et al., p. 23. This article is featured in Selected Articles from This Issue, p. 5.

Long noncoding RNA GATA2-AS1 augments endothelial Hypoxia Inducible Factor 1-α induction and regulates hypoxic signaling

Vascular endothelial cells form the inner cellular lining of blood vessels and have myriad physiologic functions including angiogenesis and response to hypoxia. We recently identified a set of endothelial cell (EC)-enriched long noncoding RNAs (lncRNAs) in differentiated human primary cell types and described the role of the STEEL lncRNA in angiogenic patterning. We sought to further understand the role of EC-enriched lncRNAs in physiologic adaptation of the vascular endothelium. In this work, we describe an abundant, cytoplasmic, and EC-enriched lncRNA, GATA2-AS1, that is divergently transcribed from the EC-enriched developmental regulator, GATA2. While GATA2-AS1 is largely co-expressed with GATA2 in ECs, GATA2-AS1 and GATA2 appear to be complementary rather than synergistic as they have mostly distinct target genes. Common single nucleotide variants (SNVs) in GATA2-AS1 exons are associated with early onset coronary artery disease (CAD) and decreased expression of GATA2-AS1 in endothelial cell lines. In most cells, HIF1-α is central to the transcriptional response to hypoxia, while in ECs, both HIF1-α and HIF2-α are required to coordinate an acute and chronic response respectively. In this setting, GATA2-AS1 contributes to the "HIF switch" and augments HIF1-α induction in acute hypoxia to regulate HIF1-α/ HIF2-α balance. In hypoxia, GATA2-AS1 orchestrates HIF1-α-dependent induction of the glycolytic pathway, and HIF1-α-independent maintenance of mitochondrial biogenesis. Similarly, GATA2-AS1 coordinates both metabolism and "tip/stalk" cell signaling to regulate angiogenesis in hypoxic ECs. Furthermore, we find that GATA2-AS1 expression patterns are perturbed in atherosclerotic disease. Together, these results define a role for GATA2-AS1 in the EC-specific response to hypoxia.

Pursuing Quality in the Application of Bladder Cancer Quality of Life Research

Patient-reported outcomes (PRO), including health-related quality of life (HRQOL) measures, represent important means for evaluating patients' health outcomes and for guiding health care decisions made by patients, practitioners, investigators, and policy makers. In spite of the large number of studies examining HRQOL in patients with bladder cancer, very few review articles investigated this topic. Because these review studies report mixed results, incorporating bladder cancer HRQOL measures into standard urological practice is not a viable option. In this non-systematic review of the literature and commentary we note some general concerns regarding PRO research, but our primary focus is on the HRQOL methodology within the context of two types of bladder cancer: muscle invasive and non-muscle invasive bladder cancer. Considering bladder cancer HRQOL as the interaction of four areas of the assessment process (i.e., what model of HRQOL to choose, what instruments are available to fit the choice, how interpretation of the resulting data fits the model, and how to derive some utility from the chosen model) and the two types of disease (i.e., muscle invasive and non-muscle invasive) may move us toward a better understanding of bladder cancer HRQOL. Establishing a useful model of perceived general health or specific symptoms is the first and most important step in developing the responsive bladder cancer HRQOL measures necessitated by clinical settings.

Cytokine-induced alteration of platelet and hemostatic function

A number of nonplatelet-specific cytokines that augment platelet recovery following chemo/radiotherapy have been described. The members of the interleukin 6 (IL-6) family have properties that influence the hematopoietic system beyond their modest thrombocytopoietic effects. Studies performed in a canine model with IL-6 have shown that this factor augments plasma fibrinogen and von Willebrand factor (vWf) concentrations and decreases the level of free protein S. IL-6 appears to decrease the bleeding time in thrombocytopenic dogs, although this effect does not seem to be due to a direct influence of the factor on endothelial vWf or tissue factor production. The factor does not directly alter platelet function in vitro, but when administered to dogs, it increases the sensitivity of the platelets to activation by thrombin. Normal platelets injected into IL-6-treated dogs, and platelets from IL-6-treated dogs injected into normal animals, survive normally. Following injection of either IL-6 or the more specific thrombocytopoietic cytokine thrombopoietin (TPO), IL-6 increases platelet responsiveness to thrombin-induced activation to a greater extent than does TPO. The data show that IL-6 has certain properties that might be construed as prohemostatic, and these properties may prove to be useful clinically.

Use of course-embedded projects for program assessment

There is increasing demand on science faculty to develop authentic assessment measures for both individual courses and undergraduate programs. We report here on a quarter-long group project used in a neurophysiology course that can be used for either purpose. Small groups of four to five students critically analyze at least 10 articles from the primary scientific literature. The end result of this process is the equivalent of a scientific review article that is presented in two formats, a 10-min oral presentation and a scientific poster presentation. Students perform better on application tasks than on analysis, synthesis, or evaluation tasks associated with the project (P < 0.025) and generally respond positively to process questions (59-82%) but less positively to task questions (36-76%) about group dynamics. The cognitive skills and basic content knowledge required to complete this project are developed throughout the undergraduate program. Thus the project is a type of culminating program experience. However, the project also assesses basic course proficiency, because students cannot analyze primary neuroscience research without an understanding of neurophysiological principles.

Expression of a foreign protein in human megakaryocytes and platelets by retrovirally mediated gene transfer

Recent progress in the culture of human megakaryocytes (MKs) has led to the capacity to produce platelets in vitro. This capability enables investigation into the possibility of modifying platelet structure and/or function by genetically altering the MK. To this end, a cDNA for the murine CD9 (mCD9) cell surface protein was introduced into MK progenitors by retrovirally mediated gene transfer and subsequently detected in cultured MKs with a monoclonal antibody (MoAb) that specifically recognizes the murine protein. CD34+ human peripheral blood or marrow progenitors, enriched by immunomagnetic bead selection, were cultured for 5 days in the presence of growth factors, including stem cell factor and thrombopoietin, to induce MK progenitors into the cell cycle. The stimulated cells were then cocultured with the mCD9 retroviral producer cell line for 3 days, followed by culture in serum-depleted medium for 3 to 7 additional days. Flow cytometry analysis using the anti-CD9 MoAb and TAB, a MoAb recognizing human GPIIb, revealed that a large proportion (40-100%) of the MKs expressed mCD9. To ascertain whether these cells were capable of producing mCD9+ platelets, flow cytometry analysis was performed at a time when proplatelets were observed in the culture. mCD9 was detected in up to 59% of the TAB+ platelet-sized particles. Because deteriorating MKs can produce platelet-sized particles in vitro, experiments were performed to determine whether mCD9+ TAB+ particles were functionally active. Addition of phorbol myristate acetate resulted in the redistribution of P-selectin (CD62) from the alpha granule to the platelet surface as detected by MoAbs S12 and G5 in three-color flow cytometry analyses. These studies showed that up to 76% of the mCD9+ TAB+ particles were functionally active. The data show that retrovirally mediated gene transfer is a viable approach for genetically altering MK progenitors, resulting in platelets that express heterologous proteins.

A cancer risk model with adaptive repair

The cancer risk model described herein first appeared in 1982. The model provides a plausible mechanism with biological underpinnings that might reasonably explain observed phenomena in cancer dose-response studies that are not being addressed by the risk models currently in use. This article is a summary and explanation of the features of the model that relate to hormesis. Data from several saccharin studies served in large part to motivate the original research, and were used to illustrate beneficial low-dose effects that could be explained by the model. The model itself is a function of linear ratios of the administered dose x. Linear ratios arise naturally from non-linear Michaelis-Menten kinetics, as described in the next section. The one-hit cancer risk model is used to illustrate the hormetic concepts brought out by linear ratios. The one-hit model is modified to account for repair and for non-linear kinetics, by using a linear ratio of the administered dose instead of the actual administered dose, and by expressing the probability that a 'hit' is repaired as a linear ratio of the administered dose. The phenomenon of hormesis - or low-dose beneficial effects-has been widely observed and accepted. Yet none of the cancer risk models currently in wide use have attempted to accommodate hormetic effects. The modified one-hit model developed herein does not attempt to account for elimination or detoxification, but nevertheless it provides plausible explanations for certain classes of observed hormetic phenomena associated with experimental testing of carcinogenic substances in animals.

Delayed-interval delivery in a quadruplet pregnancy after intrauterine death of a partial molar pregnancy and preterm delivery. A case report

BACKGROUND

Delayed-interval delivery is infrequent in twin gestation and more rare in triplet and quadruplet gestation. Coexistence of a triploid pregnancy with a normal fetus has not previously been reported to have resulted in survival of the normal fetus.

CASE

A 26-year-old woman, gravida 2, para 0-0-1-0, was diagnosed with a quadruplet pregnancy. At 16 1/2 weeks' gestation she developed preeclampsia and severe hyperemesis. Ultrasound was consistent with partial molar pregnancy in quadruplet D. Quadruplet D died in utero, and the preeclampsia and hyperemesis resolved. At 19 5/7 weeks, spontaneous rupture of the membranes and preterm labor occurred, and quadruplet A, stillborn female weighing 260 g, was delivered. With the use of antibiotic therapy, tocolysis and bed rest, the remaining two fetuses were maintained in utero until 32 6/7 weeks' gestation, when quadruplet B, a 1,470-g female, and quadruplet C, a 1,700-g female, were delivered.

CONCLUSION

This was the first reported case of surviving fetuses coexisting with a partial molar pregnancy. This case was also complicated by preterm delivery and successful delayed-interval birth in a quadruplet pregnancy.

Expression of catalytically active human cytochrome p450scc in Escherichia coli and mutagenesis of isoleucine-462

Cytochrome P450scc (P450scc) catalyzes the first step in steroid hormone synthesis, the conversion of cholesterol to pregnenolone. Human P450scc has been poorly studied due to the difficulty of purifying reasonable quantities of enzyme from human tissue. To provide a more convenient source of the human enzyme and to enable structure-function studies to be done using site-directed mutagenesis, we expressed the mature form of human P450scc in Escherichia coli. The expression system enabled us to produce larger quantities of active cytochrome than have previously been isolated from placental mitochondria. The expressed P450scc was purified to near homogeneity and shown to have catalytic properties comparable to the enzyme purified from the human placenta. The mature form of human adrenodoxin was also expressed in E. coli and supported cholesterol side chain cleavage activity with the same Vmax as that observed using bovine adrenodoxin but with a higher Km. Mutation of Ile-462 to Leu in human P450scc caused a decrease in the catalytic rate constant (kcat) with cholesterol as substrate, increased the Km for 22R-hydroxycholesterol, but did not affect the kinetic constants for 20 alpha-hydroxycholesterol. This suggests that Ile-462 lies close to the side chain binding site and that the side chains of cholesterol, 22R-hydroxycholesterol, and 20 alpha-hydroxycholesterol occupy slightly different positions in the active site.

Assessing the burden of cancer in Texas using vital statistics data

BACKGROUND

Vital statistics data were used to describe the burden of cancer in Texas.

METHODS

Average annual age-adjusted mortality data in Texas (1986 to 1990) for 17 cancer types were compared with the US data for whites and blacks and with California data for Hispanics. Trends were examined from 1980 to 1990 for the entire state and from 1976 to 1989 for 24 geographic regions within the state.

RESULTS

Mortality excesses were detected for lung and liver cancer, and deficits for colorectal, breast, and prostate cancers. Rates were generally stable from 1980 to 1990 with several exceptions (lung, liver, colon). Six areas of Texas, including four areas along the Gulf Coast, had relatively more excesses of various cancers, without a discernible pattern by cancer type.

CONCLUSIONS

Overall, Texas has fared favorably in cancer mortality when compared with the United States. Enhanced evaluation of the frequency of cancer, as well as the conduct of etiologic research, must await the availability of statewide long-term cancer incidence data.

Erythropoietin potentiates thrombus development in a canine arterio-venous shunt model

Erythropoietin (EPO) has been previously shown to affect platelet as well as red cell production. In addition, recent studies demonstrated that platelets from EPO-treated dogs are hyperreactive towards thrombin when compared to age-matched, control platelets. This report extends these observations by quantitating the thrombogenic potential of EPO in dogs. Dogs with arterio-venous (A-V) shunts received 100 U EPO/kg/day for 6 days, and thrombogenicity was serially monitored by insertion of a thrombotic surface into the A-V shunt. The resulting experimental thrombi were analyzed for platelet and erythrocyte content after formalin-fixation and chymotrypsin digestion, a technique which allows non-isotopic quantitation of cellular components. By day 5 of EPO-administration all animals demonstrated a significant increase in platelet and red cell content of the experimental thrombi; the average increase in platelet number was 2.94 +/- 0.12 fold (mean +/- 1 SE; n = 3; p = 0.006) above baseline while that for red cells was 2.46 +/- 0.18 fold above baseline (p = 0.023). After cessation of EPO, thrombogenicity returned to normal. During EPO-treatment, the percentage of thiazole orange-positive (TO+) platelets increased significantly to 17.2 +/- 1.6% (mean +/- 1 SE; n = 3) on day 5 compared to a pre-treatment level of 8.5 +/- 0.9% (p = 0.029). Although the percentage of TO+ erythrocytes also increased during the short course of EPO administration, the change was not significant. Despite the increases in TO+ cells, total platelet and erythrocyte counts did not change significantly within the time frame of these experiments. Fibrin/fibrinogen content of the experimental thrombi was unaltered with EPO-treatment. These data demonstrate that human EPO is pro-thrombotic in dogs and, in conjunction with earlier studies, suggest that hyperreactive platelets may be responsible for the potentiated thrombogenicity.

Cancer mortality among petroleum refinery and chemical manufacturing workers in Texas

Epidemiologic historical cohort studies of petroleum refinery and chemical manufacturing workers in Texas were reviewed to examine their cancer mortality in comparison to the U.S. and to assess the possible impact of cancer mortality among these workers on the State of Texas as a whole. Summary standardized mortality ratios and 95% confidence intervals were calculated for 20 cancer types, taking into account the heterogeneity of individual studies. There were 4314 cancer deaths among the 92,318 workers employed in 10 independent plant populations. Overall, there was a significant deficit in cancer mortality among petrochemical workers compared with the general U.S. population (SMR = 88, 95% CI = 80 to 96). Only the summary SMRs for brain cancer (SMR = 113, 95% CI = 96 to 133) and leukemias (SMR = 112, 95% CI = 94 to 130) approached statistical significance. Lung and liver cancer mortality excesses, noted for Texas as a whole, were decreased in these workers. Additional follow-up of these cohorts, their expansion to include minority and female workers, and additional study of possible occupational contributions to leukemia and brain cancer are recommended.

Inhibition of the acute-phase response in vivo by anti-gp130 monoclonal antibodies

The acute-phase response is believed to be an important systemic defence reaction to inflammation during infection, trauma, injury or neoplasia. Although the interleukin-6 (IL-6) family of cytokines appear to be the major regulators of the acute-phase reaction, the exact biological significance of this process remains unknown. In this study, a panel of monoclonal antibodies (Mabs) was raised against the extracellular domain of human gp130 (the common signal transducing chain of the IL-6 cytokine family) in order to inhibit the biological activity of IL-6-like cytokines in vivo. Mabs designated 4B11 and 2H4 were most effective in the inhibition of the in vitro acute-phase response on hepatoma cells and prevented the IL-6-induced growth inhibition of A375 cells. Administration of the antibodies to dogs at a dosage of 8 mg/kg/d showed that 2H4 was a potent inhibitor of the IL-6-induced (40 micrograms/kg/d) acute-phase response, abrogating IL-6-mediated increments in fibrinogen, C-reactive protein and the platelet count. This antibody, the first described to abrogate the acute-phase response in vivo, may not only permit development of a new anti-inflammatory strategy, but provides an excellent tool for defining the function of acute-phase proteins in inflammation and infection.

Is there transplacental transfer of asbestos? A study of 40 stillborn infants

An autopsy study was conducted to investigate whether there is transplacental transfer of asbestos in humans. The asbestos burden of lung, liver, skeletal muscle, and placenta digests of 40 stillborn infants was determined using a bleach digestion method. The fibers detected in the tissue digests were characterized as to the type of asbestos, using electron microscopy, energy-dispersive x-ray analysis, and selected-area diffraction analysis. Placental digests of 45 full-term, liveborn infants were similarly processed as controls. Low levels of small, thin, uncoated asbestos fibers were detected in the placentas and organs of 37.5% of the stillborn infants (15 of 40). The fiber sizes ranged from 0.05 to 5.0 microns in length and 0.03 to 0.3 micron in width, with a mean length of 1.15 microns and a mean width of 0.069 micron. Maximum numbers of fibers were found in the lungs (mean 235,400 fibers/g; n = 10), followed by liver (mean 212,833 fibers/g; n = 6), placenta (mean 164,500 fibers/g; n = 4), and skeletal muscle (80,000 fibers/g; n = 1). The fibers were detected at all stages of gestation and showed no association with gestational age. A significant association was found between fiber presence and working mothers, and positive but nonsignificant associations were found with maternal history of drug abuse, previous abortions, and fetal maceration. No association was found between premature rupture of membranes and fiber presence. No fibers were detected in the 45 placentas of the liveborn control infants. There was a highly significant difference in the asbestos fiber counts of the placentas of the stillborn and liveborn infants (P < .001). Our studies demonstrate the presence of short and thin asbestos fibers in stillborn infants and their positive association with working mothers.

Ovine fetal-placental cocaine pharmacokinetics during continuous cocaine infusion

OBJECTIVE

To investigate fetal-placental cocaine clearance, and to determine the fetal catecholamine and cardiovascular responses to continuous intravenous cocaine infusion in fetal sheep.

METHODS

Eleven pregnant ewes and their fetuses (127 +/- 2 days' gestation; term 150 days) were chronically instrumented. Fetuses received intravenous cocaine at 0.05, 0.1, or 0.2 mg/kg/minute. Fetal cardiovascular and hematologic measurements were made before and serially for 90 minutes after initiation of the cocaine infusion.

RESULTS

Steady-state fetal plasma cocaine concentrations were observed by 15 minutes of infusion and averaged 136 +/- 11, 318 +/- 65, and 610 +/- 36 ng/mL, respectively, at each dose. Fetal-placental cocaine clearance rate was independent of dose (337 +/- 39 mL/kg/minute), indicating that it is a first-order pharmacokinetic process. Fetal plasma concentration of benzoylecgonine, a principle cocaine metabolite, increased throughout the study to approximately 25% above cocaine levels by 90 minutes. There were significant increases in fetal heart rate (from 169 +/- 11 to 242 +/- 36 beats per minute), mean blood pressure (from 53 +/- 4 to 63 +/- 5 mmHg), and systolic blood pressure (from 68 +/- 2 to 80 +/- 5 mmHg), with a corresponding increase in catecholamine levels seen in the fetuses infused with 0.2 mg/kg/minute. These changes were not seen in the fetuses given lower doses of cocaine.

CONCLUSION

Fetal-placental clearance of cocaine is a rapid, first-order pharmacokinetic process. During prolonged cocaine exposure, plasma benzoylecgonine concentrations accumulate significantly. Significant catecholamine and cardiovascular changes are seen in fetal sheep with a continuous infusion of cocaine at 0.2 mg/kg/minute or greater.

Relative reactivity of platelets from thrombopoietin- and interleukin-6-treated dogs

Previous reports have shown that interleukin-6 (IL-6) enhances the responsiveness of platelets to thrombin stimulation and has modest thrombocytopoietic effects in vivo. Thrombopoietin (TPO; mpl ligand) has been shown to have dramatic thrombocytopoietic effect in vivo, but little is known of its capacity to alter platelet function. In this study, a direct comparison of the effects of IL-6 and TPO on platelet function in dogs has been performed, with modest doses of TPO (1 microgram/kg/d) chosen to match or moderately exceed the platelet counts achieved with IL-6 (40 micrograms/kg/d) for 10 days. Platelet responsiveness to thrombin stimulation was assessed in TPO-treated, IL-6-treated, and control dogs by flow cytometric measurement of P-selectin expression. On day 5, the dose of thrombin promoting half maximal stimulation (EC50) of platelets was not significantly changed in TPO-treated dogs, whereas in IL-6-treated dogs the EC50 decreased to 73.1% +/- 6.1% (mean +/- 1 SD; n = 5) of control values (P < 0.01). These experiments were performed on both gel-filtered platelets and washed whole blood, indicating that the observed changes in EC50 were caused by cytokine-mediated alteration of platelets rather than plasma components. Because it has been shown that thiazole orange specifically labels a subpopulation of dog platelets that is less than 24 hours old, the thrombin responsiveness of these young, newly synthesized platelets was determined. The EC50 of thiazole orange-positive platelets from IL-6-treated dogs decreased dramatically by day 5 to 46.5% +/- 13.1% (n = 4) of control values (P < 0.001), whereas TPO-treated dogs did not significantly change. When TPO was directly incubated with platelets ex vivo, no effects on either thrombin-mediated P-selectin expression or adenosine diphosphate-induced fibrinogen binding were observed. These data show that IL-6 alters platelet function, as measured by reactivity to thrombin, whereas TPO does not. This divergence in function is observed even though TPO is equally, or more, effective at promoting platelet production under these experimental conditions.

A survey of actinic keratoses among paraquat production workers and a nonexposed friend reference group

Follow-up on two reports of an excess of keratoses among paraquat production workers was conducted to evaluate the contribution of occupational exposures to the prevalence of keratoses among workers in a paraquat production plant in Texas. A cross-sectional study design was used to compare the prevalence of keratoses among current workers to an age, race, and sex frequency-matched group of their friends who had never worked at the plant. The analysis is based on 112 workers and 232 friends. Exposure, outcome, and covariables used in the analyses were obtained from an interview questionnaire, dermatology exam, and company records. Overall, the prevalence proportion of the presence of any actinic keratoses among workers and friends was similar (0.30 and 0.28, respectively). Among high cumulative exposed workers, the prevalence of any actinic keratoses was 0.40 compared to 0.20 among low-exposed workers and 0.28 among friends. These results were further explored using a multiple logistic regression approach to adjust for known risk and possibly confounding variables. Statistically significant high risks of actinic keratoses were demonstrated for freckling before age 16 years, older age, suntanning behaviors, occupational exposure to polycyclic aromatic hydrocarbons (PAH), and Fitzpatrick skin type. There was no significant contribution of overall exposure status (worker vs. friend). Similar to the crude analysis, the odds of actinic keratoses of high-exposed workers compared to friends was 1.9 (confidence interval [CI] = 0.9-4.2) whereas the comparable odds ratio for low-exposed workers vs. friends was 0.6 (CI = 0.2-1.7). These data do not demonstrate an excess of actinic keratoses overall nor any consistent increase in the odds of keratoses with an increase in plant exposure level.

Comments on ;Optimal training of thresholded linear correlation classifiers' [with reply]

A difficulty with the application of the closed-form training algorithm for the neocognitron proposed by T.H. Hildebrandt (ibid., vol.2, p.557-88, Nov. 1991) is reported. In applying this algorithm the commenters have observed that S-cells frequently fail to respond to features that they have been trained to extract. Results which indicate that this training vector rejection in an important factor in the overall classification performance of the neocognitron trained using Hildebrandt's procedure are presented. In reply, Hildebrandt explains that the negative results obtained by the commenter are not specific to the proposed algorithm and are easily explained in terms of set theory.

Characteristics of a novel rat anti-mouse platelet monoclonal antibody: application to studies of megakaryocytes

Using murine platelets as an immunogen, a rat monoclonal antibody (designated 4A5) that recognizes only murine blood platelets and marrow megakaryocytes was developed. The extent of binding of 4A5 to platelets was dependent upon their state of activation. Following phorbol ester, ionophore, or thrombin stimulation of resting platelets, a decrease of > 50% in the binding of 4A5 was observed by flow cytometry. This decrease in antibody binding to the platelets was accompanied by an increase in antibody released into the platelet-free supernatant following platelet activation. When platelets were first radioiodinated, followed by activation and incubation of the platelet-free supernatant with 4A5-derivatized beads, no precipitable counts were observed compared with control resting platelets. This suggests that antibody release was related to an activation-dependent conformational change in the 4A5 epitope. Following solubilization of biotinylated platelets, 4A5 bound to an 80-kd membrane protein. Immunohistochemical studies with 4A5 showed that megakaryocytes could be identified both in vitro and ex vivo. When marrow was first stained histochemically with 4A5 followed by staining for acetylcholinesterase, the distribution of stained cells was similar. Flow cytometric analysis using 4A5 and propidium iodide showed that the antibody could be used to identify megakaryocytes for ploidy analysis in vivo or in vitro. 4A5 was capable of inducing a moderate thrombocytopenia in mice compared with polyclonal anti-platelet serum. When bound to plastic or to magnetic beads, 4A5 could be used to purify murine megakaryocytes to homogeneity. The data suggest that monoclonal antibody 4A5 will be useful in quantitative studies of murine platelets and megakaryocytes.

Thrombocytopoiesis in normal and sublethally irradiated dogs: response to human interleukin-6

The response of megakaryocytes and platelets to the administration of recombinant human interleukin-6 (IL-6) was investigated in normal and sublethally irradiated dogs. IL-6 was administered for 2 weeks at doses of 10 to 160 micrograms/kg/d to normal animals to assess dose-response and toxicity. Subsequently, 40, 80, or 160 micrograms/kg/d for 2 weeks was administered to animals treated with 200 cG total body irradiation. Analysis of normal dogs showed a significant increment in the platelet count detectable approximately 11 days after initiation of IL-6 at all administered doses. Large platelets greater than 6.3 microns in diameter were observed 1 day after beginning IL-6, progressively increasing to as many as 19.1% of the total circulating platelets by day 10. The ploidy distribution of the marrow megakaryocytes did not differ from the normal at doses of less than or equal to 80 micrograms/kg/d, but at 160 micrograms/kg/d, a shift toward higher ploidy cells was noted. No change in total white count was noted; however, a decrease in hematocrit was seen at all doses. In the irradiated animals, the platelet count recovered earlier in the IL-6-treated dogs than in the controls, but no consistent change in the ploidy distribution was observed irrespective of dose. Large platelets were also noted in the treated animals, comprising up to 6.9% of the total platelet count. Fibrinogen levels were elevated to greater than 4 times normal. A significant decrease in hematocrit was seen in all animals, while no consistent change was noted in the white count. Elevations in serum cholesterol, triglycerides, and alkaline phosphatase, together with a decline in serum albumin were observed in all the treated animals (both normal and irradiated), but clinical symptoms were observed only in the dogs receiving greater than or equal to 80 micrograms/kg/d. The data show that IL-6 alone is capable of enhancing platelet recovery in dogs with bone marrow suppression.

Interleukin-6 mRNA and protein increase in vivo following induction of acute thrombocytopenia in mice

Induction of experimental thrombocytopenia in rodents results in the enhancement of megakaryocytic growth and differentiation. Interleukin-3 (IL-3) and IL-6, cytokines with a broad spectrum of biologic activities, stimulate megakaryocytopoiesis in vitro. To determine if expression of these factors might increase in response to experimental thrombocytopenia, we measured steady-state levels of IL-3 and IL-6 mRNA following rabbit antiplatelet serum (APS) injection. Groups of mice were injected intravenously with 0.2 mL APS while control animals received rabbit antilymphocyte serum (ALS), normal rabbit serum (NRS), or phosphate-buffered saline (PBS). At various times up to 72 hours after injection mice were exsanguinated and splenectomized. Platelet counts in the experimental animals were less than 12% of controls. Splenic RNA was hybridized in solution to 32P-UTP-labeled cRNA probes for IL-3 and IL-6. RNase-resistant hybrids were resolved on denaturing gels and visualized autoradiographically. IL-3 hybrids were undetectable at all time points tested, irrespective of the film exposure time or specific activity of the probe. Conversely, IL-6 hybrids were easily visualized and showed peak expression at 1.5 to 2.0 hours. By 3 hours, IL-6 mRNA had returned almost to the level of the controls. Similar results were observed in the bone marrow, although maximal IL-6 mRNA in that tissue was observed 4 hours following APS administration. To determine if this mRNA increment was associated with a concomitant increase in bioactive protein, serum was tested for its ability to stimulate IL-6-dependent B9 cells. At 1.75 hours following injection, experimental animals showed a small but significant increment in IL-6 activity compared with controls (200 +/- 30 U/mL IL-6 compared with 129 +/- 17 U/mL in ALS-injected controls, 106 +/- 17 U/mL in NRS-injected controls and 84 +/- 17 U/mL in PBS-injected controls). The data show that IL-6 mRNA and bioactive protein increase in response to acute immunothrombocytopenia, while no increment in IL-3 is detectable. These results suggest that IL-6 may play a role in the physiologic response to acute immunothrombocytopenia.

Canine megakaryocytopoiesis: analysis utilizing a monoclonal antibody to a 140-kd dog platelet protein

The dog, a convenient and relatively large animal whose size permits repetitive blood and marrow sampling, marrow biopsy, and mechanical apheresis, would be a suitable experimental model for the study of in vivo megakaryocytopoiesis. A monoclonal antibody to a 140-kd dog platelet membrane protein has been developed that reacts with canine megakaryocytes. Using the fluoresceinated derivative of this antibody to identify megakaryocytes and propidium iodide staining to measure relative DNA content, the DNA distribution of megakaryocytes in dog bone marrow or in cultured dog marrow cells could be rapidly assessed by flow cytometry. Normal dogs showed a modal ploidy of 16N (54%), with 17% 8N and 16% 32N. In contrast, dogs made thrombocytopenic by plateletpheresis showed a shift in distribution to higher ploidy cells (36% 32N). The data show that use of a specific marker of megakaryocytes in combination with flow cytometric analysis is an accurate and reproducible method of assessing megakaryocytopoiesis in a convenient and easily manipulable animal model.

Medical management of acromegaly due to ectopic production of growth hormone-releasing hormone by a carcinoid tumor

A 59-yr-old woman with a disseminated carcinoid tumor was evaluated for acromegaly. She had previously undergone a hypophysectomy for acromegaly and an enlarged pituitary, with a reduction in her serum GH levels from 100 to 4 micrograms/L. Recurrence of acromegalic symptoms 2 yr later was accompanied by elevated serum GH (16 micrograms/L) and insulin-like growth factor I (IGF-I; 528 micrograms/L) and plasma GHRH levels (12 micrograms/L; normal, less than 30 ng/L). Computed tomographic scan did not reveal pituitary enlargement. Metastatic carcinoid tissue in bone removed at biopsy contained GHRH (100 pg/mg tissue). High performance liquid chromatography of plasma GHRH revealed predominantly GHRH-(3-40)-OH, a biologically inactive GHRH metabolite, along with mature GHRH forms, while carcinoid tissue contained both GHRH-(1-40)-OH and GHRH-(1-44)-NH2. Treatment with pergolide initially resulted in reduction in serum GH and IGF-I levels and amelioration of symptoms of acromegaly. However, after 14 months of pergolide therapy, serum GH levels increased despite administration of up to 1000 micrograms pergolide/day. Plasma GHRH levels remained elevated throughout the treatment period. Subsequent treatment with SMS 201-995, a long-acting somatostatin analog, for over 1 yr resulted in sustained reductions of ectopic GHRH secretion, GH hypersecretion, and IGF-I levels. Plasma GHRH levels correlated with simultaneously measured serum GH levels in response to acute SMS 201-995 administration. SMS 201-995 was an effective medical treatment for acromegaly caused by ectopic GHRH production in this patient.

Mitotic inhibition and aneuploidy induction by naturally occurring and synthetic estrogens in Chinese hamster cells in vitro

We used a predominantly diploid Chinese hamster cell line to test a number of naturally occurring and synthetic estrogens for their ability to arrest cells at metaphase, their potential for allowing anaphase recovery, and their capability of inducing aneuploid progeny. The chemicals employed included diethylstilbestrol, dienestrol, hexestrol, beta-estradiol, ethynylestradiol and estriol. We also tested progesterone, estrone and testosterone in this regard. Only estrogens and their synthetic analogs caused mitotic arrest and aneuploidy, while progesterone, estrone and testosterone did not cause mitotic disturbances. Among the estrogens, DES was the most effective arrestant on a comparative molar basis, whereas dienestrol was most potent over a wide range of concentrations. Estriol was the least potent as an arrestant but was an effective inducer of aneuploidy. The addition of a metabolic activator (S9) did not alter the ability of DES to arrest mitosis. Following the removal of the drugs, cells were able to quickly reorganize a spindle apparatus and enter anaphase. Diethylstilbestrol, dienestrol, hexestrol, beta-estradiol, ethynylestradiol and estriol caused significant increase in aneuploidy within a narrow range of high concentrations in recovering cell populations. Aneuploidy was induced in a non-random manner. Immunofluorescence studies with anti-tubulin antibody indicate that estrogens may have a mechanism of mitotic arrest similar to that of colchicine and colcemid, viz inhibiting the polymerization of tubulin to form microtubules. These data suggest that the interaction between estrogens and microtubules may mediate the induction of aneuploidy in somatic cells. Aneuploidy induction by DES and similar compounds may be related to their carcinogenic potential.

Production of monoclonal antibodies against parainfluenza 3 virus and their use in diagnosis by immunofluorescence

Monoclonal antibodies were produced against parainfluenza virus type 3 (PI-3) and used to identify PI-3 clinical isolates in cell culture and PI-3 antigen in cells obtained from nasopharyngeal (NP) washes of patients. Two (2E9 and 4G5) of the three monoclonal antibodies characterized reacted by immunoblotting with a 67,000-dalton PI-3 protein, and one antibody (4E5) reacted with two viral proteins in the range of 29,000 to 31,000 daltons. The three monoclonal antibodies did not cross-react by indirect immunofluorescence (IFA) with PI-1 or PI-2 and identified by IFA 18 isolates of PI-3 in cell culture. The 2E9 antibody reacted with PI-3 antigen in cells of 8 NP wash specimens that also yielded PI-3 in cell culture. Cells from 12 specimens reactive by IFA for respiratory syncytial virus, 1 specimen yielding adenovirus in cell culture, and 5 specimens yielding influenza virus were not reactive.

Extrahypothalamic growth-hormone-releasing factor (GRF) secretion is a rare cause of acromegaly: plasma GRF levels in 177 acromegalic patients

To assess the frequency with which acromegaly is caused by ectopic secretion of GRF, we collected plasma samples from 177 unselected acromegalic patients. The samples together with those of three acromegalic patients with previously diagnosed tumors secreting GRF and of normal subjects were assayed in 3 independent GRF RIAs. Plasma immunoreactive GRF (IR-GRF) levels in normal subjects were either undetectable or detectable at levels up to 62.5 pg/ml. In none of the 177 specimens from acromegalic patients were IR-GRF values detectable in all assays, and in the most sensitive assay, the levels were similar to those in normal subjects, with the highest level measuring 82 pg/ml. In contrast, plasma IR-GRF found in the 3 patients with tumors that secreted GRF ranged from 2.0-24.4 ng/ml. These data suggest that extrahypothalamic GRF secretion is a rare cause of acromegaly. However, it is important that this rare cause of acromegaly be diagnosed before the patient has unnecessary surgery and/or irradiation directed at the pituitary. We recommend that plasma IR-GRF be measured in each new acromegalic patient.