Multimodal surveillance of SARS-CoV-2 at a university enables development of a robust outbreak response framework.

BACKGROUND: Universities are vulnerable to infectious disease outbreaks, making them ideal environments to study transmission dynamics and evaluate mitigation and surveillance measures. Here, we analyze multimodal COVID-19-associated data collected during the 2020-2021 academic year at Colorado Mesa University and introduce a SARS-CoV-2 surveillance and response framework. METHODS: We analyzed epidemiological and sociobehavioral data (demographics, contact tracing, and WiFi-based co-location data) alongside pathogen surveillance data (wastewater and diagnostic testing, and viral genomic sequencing of wastewater and clinical specimens) to characterize outbreak dynamics and inform policy. We applied relative risk, multiple linear regression, and social network assortativity to identify attributes or behaviors associated with contracting SARS-CoV-2. To characterize SARS-CoV-2 transmission, we used viral sequencing, phylogenomic tools, and functional assays. FINDINGS: Athletes, particularly those on high-contact teams, had the highest risk of testing positive. On average, individuals who tested positive had more contacts and longer interaction durations than individuals who never tested positive. The distribution of contacts per individual was overdispersed, although not as overdispersed as the distribution of phylogenomic descendants. Corroboration via technical replicates was essential for identification of wastewater mutations. CONCLUSIONS: Based on our findings, we formulate a framework that combines tools into an integrated disease surveillance program that can be implemented in other congregate settings with limited resources. FUNDING: This work was supported by the National Science Foundation, the Hertz Foundation, the National Institutes of Health, the Centers for Disease Control and Prevention, the Massachusetts Consortium on Pathogen Readiness, the Howard Hughes Medical Institute, the Flu Lab, and the Audacious Project.

Monolithic microfabricated valves and pumps by multilayer soft lithography.

Soft lithography is an alternative to silicon-based micromachining that uses replica molding of nontraditional elastomeric materials to fabricate stamps and microfluidic channels. We describe here an extension to the soft lithography paradigm, multilayer soft lithography, with which devices consisting of multiple layers may be fabricated from soft materials. We used this technique to build active microfluidic systems containing on-off valves, switching valves, and pumps entirely out of elastomer. The softness of these materials allows the device areas to be reduced by more than two orders of magnitude compared with silicon-based devices. The other advantages of soft lithography, such as rapid prototyping, ease of fabrication, and biocompatibility, are retained.

Gravitational lensing reveals ionizing ultraviolet photons escaping from a distant galaxy.

During the epoch of reionization, neutral gas in the early Universe was ionized by hard ultraviolet radiation emitted by young stars in the first galaxies. To do so, ionizing ultraviolet photons must escape from the host galaxy. We present Hubble Space Telescope observations of the gravitationally lensed post-reionization galaxy PSZ1-ARC G311.6602-18.4624 (nicknamed the "Sunburst Arc"), revealing bright, multiply imaged ionizing photon escape from a compact star-forming region through a narrow channel in an optically thick gas. The gravitational lensing magnification shows how ionizing photons escape this galaxy, contributing to the reionization of the Universe. The multiple sight lines to the source probe absorption by intergalactic neutral hydrogen on a scale of less than a few hundred parsecs.

Clinicopathological characteristics and non-adhesive organ culture of insulinomas.

BACKGROUND AND AIMS: Insulinoma is a very rare type of islet cell tumour, but nevertheless the most common endocrine tumour of the pancreas. We aimed at reviewing our clinical experience with this tumour type and to assess whether organ culture could be obtained from surgically resected insulinoma material. MATERIAL AND METHODS: All patients with insulinomas (6 men and 10 women) referred to Haukeland University Hospital between 1986 and 2006 were included in the study. Median age of onset was 53 years (range 21-74). Biochemical diagnosis was established during a 72 h fast test. Imaging and localization of the tumours were performed with intra-operative ultrasonography, endoscopic ultrasonography, CT-scan and/or transcutaneous ultrasonography. For six patients, organ cultures were set up from tumour tissue fragments. RESULTS: The annual incidence of insulinoma was 0.8 per million. The patients generally presented with non-specific, episodic symptoms, which often were mistaken for cardiovascular, neurological or diabetic disease and in some cases delayed the diagnosis with several years. Two patients had diabetes prior to the diagnosis of insulinoma. Patient weight gain was probably due to increased food intake, compensating for the hypoglycemia. Intra-operative ultrasonography detected all tumours correctly, whereas 73% were detected by endoscopic ultrasonography and 38% by CT scan. Five insulinomas were located in the head, eight in the body and three in the tail of the pancreas. All were removed by open-access surgery, eleven cases by resection and five by enucleation. One tumour was malignant with liver metastases and two patients had tumours defined as borderline. Insulinoma tissue fragments developed into spheroids during the first week of culturing and insulin secretion into the media was demonstrated. CONCLUSIONS: Insulinomas are rare and diagnostically challenging tumours. Intra-operative ultrasonography was superior to other imaging modalities to locate the lesion. In organ culture, insulinomas readily form spheroids which may be used to yield insight into beta-cell biology.

Saliva cortisol measurement: simple and reliable assessment of the glucocorticoid replacement therapy in Addison's disease.

No ideal parameter is available for assessment of the glucocorticoid replacement therapy in Addison's disease. Serum cortisol day-curves can be used to monitor the therapy, but this technique is cumbersome and expensive. We evaluated the potential for saliva cortisol measurement in this setting. We found excellent correlation between serum and saliva cortisol after oral intake of cortisone acetate (no. 7) or iv administration of hydrocortisone (no. 4) (Pearson's R=0.83-0.98, p<0.002). A morning dose of 12.5 mg cortisone acetate yielded wide interindividual variations in cortisol levels in saliva. Saliva cortisol measurements were successfully adopted to evaluate and adjust doses in outpatients. We conclude that cortisol measurement in saliva is practical and reliable, and is preferable to serum cortisol measurement in the assessment of the glucocorticoid replacement therapy. Our results confirm that only a minority of patients require more than 12.5 mg of cortisone acetate (equivalent to 10 mg hydrocortisone) in the morning to have sufficient cortisol levels during the first part of the day.

Progesterone-binding cyst protein in human breast tumor cytosol.

Breast tumor cytosol has been analyzed for the presence of a progesterone-binding protein (PBCP), commonly present in benign breast cysts in huge concentrations. In 377 primary carcinoma investigated PBCP was present in measurable quantities in 60.7% using "rocket" immunoelectrophoresis. Concentrations of PBCP ranged from 0 to 12.4% of total cytosol protein with an average of 4.0 micrograms/mg cytosol protein. The distribution of PBCP values seems to suggest two tumor populations, one of which is lacking in PBCP and the other showing a lognormal distribution. In malignant tumors PBCP levels were negatively correlated (P = 0.024) to estrogen receptor but not to (P = 0.38) progestin receptor levels. There was a highly significant (P less than 0.001) positive correlation to cytosol albumin concentration which suggests an extracellular localization of PBCP possibly caused by restricted lymphatic drainage of tumor tissue. In benign breast tumors, mainly fibroadenomas, both PBCP incidence (81%) and average concentration (13.5 micrograms/mg protein) was higher than in malignant tumors. A positive correlation to sex-hormone receptor levels were observed indicating that PBCP production could be under hormonal control in this type of tumor development. In 71 metastatic tumors examined PBCP incidence was far less than in primary tumors (P less than 0.001) and the levels seen were also considerably lower. PBCP holds promise as a marker of tumors in an early stage of development and/or with a low metastatic potential.

Improved measurement of androgen receptors in human breast cancer.

Molybdate-stabilized androgen receptors have been quantitated in cytosols derived from 1026 malignant breast tumors including all new cases of primary breast cancer reported in the western region of Norway during the 3-year period 1985-1987. A simple single point saturation assay using the synthetic labeled ligand methyltrienolone was evaluated for this purpose. This approach also allowed the simultaneous determination of estrogen and progesterone receptor from the same cytosol preparation. The cytosol content of albumin was also recorded in order to control for dilution by extracellular proteins. Androgen receptor was the sex hormone receptor most frequently found both in primary and secondary breast cancer. In primary tumors 84.9% (723 of 852) showed a cytosol concentration higher than 10 fmol/mg protein compared to 71.2 and 67.1% for estrogen and progesterone receptors, respectively. This incidence is about 2 times higher than previously reported for androgen receptors in the literature and may be due to the stabilizing effects of molybdate and a serine protease inhibitor on the recovery of active binding sites in cytosol. Cytosol concentration of androgen receptor is generally lower than that of the other sex hormone receptors; the average level was 65.5 fmol/mg cytosol protein compared to 86.8 and 84.7 for estrogen and progesterone receptors, respectively. Both incidence and cytosol concentrations were lower for all sex hormone receptors in soft tissue metastasis than in the primary tumor. This decrease is not likely to be due to differences in tumor cellularity since metastatic tumors appear to be more cellular as judged from a lower cytosol content of extracellular proteins (albumin). No significant differences were observed in any parameter investigated between different metastatic sites (skin, lymph nodes). Androgen receptor levels were strongly correlated to estrogen and progesterone receptor concentration in both primary and secondary cancers. Cytosol androgen receptor concentration increases with age. This increase is more significant in metastatic than in primary tumors. Evidently, tumor cellularity is a confounding factor in primary tumors since tumor cytosols from younger patients showed a higher content of extracellular proteins. Receptor levels in lymph node metastasis did not exhibit age dependence. This may suggest that locally produced factors rather than circulating levels of sex steroids modulate tumor receptor expression. In metastatic tissues androgen receptors are present with twice the frequency of progesterone receptors and one in four of these tumors express androgen receptor as their sole sex hormone receptor. This supports the view that some of the beneficial effects of high dose progestin treatment of advanced breast cancer are mediated through the androgen receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Growth control of human mammary cancer cells (MCF-7 cells) in culture: effect of estradiol and growth factors in serum-containing medium.

The growth control of estrogen-dependent mammary cancer is very complex and only partly understood. The present study was undertaken in order to establish conditions for growth control of MCF-7 cells in monolayer culture with focus on the effect of estradiol-17 beta, fetal calf serum, and growth factors. The effect of charcoal-stripped fetal calf serum (CSFCS) on cell growth was dependent upon the presence of hormones or growth factors in the medium. In the presence of insulin (or insulin-like growth factor 1) and in the absence of estradiol-17 beta, increasing concentrations of CSFCS, 0.625-20%, produced a bell-shaped growth response curve. Serum concentrations greater than 2.5% inhibited cell growth in the absence of estradiol-17 beta, whereas CSFCS in a dose-dependent way up to 10% stimulated growth in the presence of estradiol-17 beta (5 x 10(-10) mol/liter). The growth inhibitory effect of CSFCS could not be demonstrated in the absence of insulin (or insulin-like growth factor 1) and estradiol-17 beta. CSFCS stimulated growth in a dose-dependent way in the presence of estradiol-17 beta and also in the absence of insulin. Both the putative growth inhibitor and stimulator were found to be heat stable and not dialyzable. Epidermal growth factor stimulated growth but was unable to eliminate the growth inhibitory effect of 5-10% CSFCS. Interleukin-1 alpha inhibited MCF-7 cell growth in a dose-dependent way and produced a 75% reduction in cell number at a concentration of 5 x 10(-10) mol/liter. This inhibition was almost totally overcome by estradiol-17 beta. It is concluded that serum appears to contain factors with both stimulatory and inhibitory effects on the growth of MCF-7 cells. The inhibitory effect can be eliminated by estradiol (5 x 10(-10) mol/liter). In the presence of estradiol cell growth is stimulated by CSFCS in a dose-related way up to 5-10%. Taken together these data seem to indicate that estradiol stimulates cell growth in two principal ways: partly by eliminating the effect of an inhibitor, in support of a "negative hypothesis," and partly by an effect whereby estradiol permits a growth stimulator in CSFCS to be expressed, in support of the "indirect positive hypothesis."

Predictive value of tumour cell proliferation in locally advanced breast cancer treated with neoadjuvant chemotherapy.

We previously reported that defects in apoptotic pathways (mutations in the TP53 gene) predicted resistance to doxorubicin monotherapy. The aim of this study was to evaluate whether cell proliferation, as assessed by mitotic frequency and Ki-67 levels, may provide additional predictive information in the same tumours and to assess any potential correlations between these markers and mutations in the TP53 gene and erbB-2 overexpression. Surgical specimens were obtained from ninety locally advanced breast cancers before commencing primary chemotherapy consisting of weekly doxorubicin (14 mg/m2) for 16 weeks. 38% of the patients had a partial response (PR) to therapy, 52% had stable disease (SD) while 10% had progressive disease (PD). Univariate analysis showed a significant association between a high cell proliferation rate (expressed as a high mitotic frequency) and resistance to doxorubicin (P = 0.001). Further analyses revealed this association to be limited to the subgroup of tumour expressing wild-type TP53 (P = 0.016), and TP53 mutation status was the only factor predicting drug resistance in the multivariate analyses. The finding that a high mitotic frequency, as well as a high Ki-67 staining, correlated to TP53 mutations (P = 0.001 for both), suggests TP53 mutations are the key predictor of drug resistance, although cell proliferation may play an additional role in tumours harbouring wild-type TP53. Regarding overall (OS) and relapse-free survival (RFS), multivariate analyses (Cox' proportional hazards regression) revealed a high histological grade and negative oestrogen receptor (ER) status to be the variables that were most strongly related to breast cancer death (P = 0.001 and P = 0.001, respectively). A key reason for this difference with respect to the factors predicting chemotherapy resistance could be due to the adjuvant use of tamoxifen in all patients harbouring ER-positive tumours.

Modulation of mouse estrogen receptor transcription activity by protein kinase C delta.

The effect of protein kinase C (PKC) delta on the transcriptional activity of the mouse estrogen receptor was investigated. The receptor was expressed transiently in Cos-1 and NIH3T3 cells in the presence of wild-type, dominant negative or constitutively active forms of PKC delta. Transfection experiments demonstrated that PKC delta stimulated both unliganded and liganded estrogen receptor transcriptional activity. This stimulatory effect was not observed using PKC alpha or PKC epsilon. 4-Hydroxytamoxifen and the pure anti-estrogen ICI 164,384 reduced receptor transcriptional activity in the presence of PKC delta. The stimulatory effect of PKC delta on estrogen receptor transcriptional activity was mediated by the N-terminal activation function 1 (AF-1) domain. The reduced stimulatory effect of PKC delta on transcriptional activity of the phosphorylation defective mutant of estrogen receptor suggests that phosphorylation of serine 122 in the AF-1 region may mediate the modulatory effect of PKC delta. Wild-type PKC delta caused a twofold increase in estrogen receptor phosphorylation, while a dominant negative mutant of PKC delta reduced the receptor phosphorylation to five percent of that caused by wild-type PKC delta. Our results suggest that PKC delta participates in the signaling pathways that lead to estrogen receptor phosphorylation and its effect on estrogen receptor transcriptional activation is both cell type and promoter specific.

Microbubble-induced phospholipase C activation does not correlate with platelet aggregation.

The effect of nitrogen-(N2-)microbubbles on platelets resembles that of common platelet agonists with respect to aggregation and secretion, but is considerably slower and is poorly inhibited by aspirin. This paper reports the effect of microbubbles on platelet phospholipase C activity in gelfiltered human platelets prelabelled with [32P]Pi ([32P]-GFP). The experiments were run in the presence of an ADP scavenging system in order to rule out effects of ADP. Stimulation of [32P]-GFP for 30 min with microbubbles caused a significant reduction in single platelets (p < 0.0004) and a significant increase in 32P-activity in the phosphatidic acid (PA) fraction (p < 0.02). Epinephrine potentiated the microbubble-induced reduction in single platelets (p < 0.05), but did not enhance the amount of 32P in the platelet [32P]PA fraction. The 32P-radioactivity in the PI-fraction increased with time to a similar extent when [32P]-GFP was stirred for 30 min in absence of microbubbles as it did after 30 min of agonist exposure. There were no significant changes in the [32P]PIP and [32P]PIP2 fractions. Aspirin abolished the microbubble-induced increase in 32P-activity in the PA fraction, but had no significant effect on the reduction in single platelets. Aspirin had a small but significant, reducing effect on platelet aggregation induced by a combination of epinephrine and microbubbles (p < 0.05). With epinephrine, however, aspirin did not completely abolish the increase in [32P]-PA. It is concluded that microbubbles alone cause platelets to aggregate by a novel mechanism that operates independent of cyclooxygenase-dependent arachidonic acid metabolites and phospholipase C activation.

Microbubble-induced serotonin secretion in human platelets.

The effect of nitrogen (N2) microbubbles on platelets resembles that of common platelet agonists with respect to aggregation (Thorsen T et al., Undersea Biomed Res 1986; 13: 289-303). In the present study we examined the effect of microbubbles on platelet secretion of preloaded 14C-serotonin. We demonstrate that stirring of platelet-rich plasma with N2-microbubbles causes a loss of single platelets that is associated with secretion. However, secretion did not increase above baseline values until after 20 min of microbubble exposure, when platelet aggregation had reached 40%. After that time the secretion rate increased. There was no correlation between secreted serotonin and the degree of platelet aggregation. Although no 14C-serotonin secretion occurred in presence of acetylsalicyclic acid (ASA), microbubble-induced platelet aggregation was only marginally reduced. Epinephrine alone caused significant platelet aggregation but no 14C-serotonin secretion and it enhanced N2-microbubble-induced platelet aggregation and secretion; ASA completely prevented secretion under these circumstances but failed to abolish the enhancement of aggregation compared with microbubbles alone. Earlier studies have shown that platelets adhere to the bubble surfaces (Thorsen T et al., Undersea Biomed Res 1987; 14: 45-59). The results in the present study indicate that non-adhering platelets in the bulk phase are not activated by means of autocrine stimulation through dense granule material.

Alterations in the metabolism of oestrogens during treatment with aminoglutethimide in breast cancer patients. Preliminary findings.

In this small study, the effect of aminoglutethimide on the disposition of oestrogens in women with advanced breast cancer was investigated using bolus injections of 4-[14C]-oestradiol and 6,7-[3H]-oestrone sulphate, alone or in combination. No alterations in oestrogen disposition were seen after short term (6 hours) aminoglutethimide administration. During long term (3 weeks to 8 months) aminoglutethimide treatment mean 4-[14C]-oestradiol clearance was not changed. 14C-Oestrone sulphate AUC was reduced by 43% at a low dose of aminoglutethimide (125 mg twice daily) and by 65% at a high dose (250 mg 4 times daily) with hydrocortisone acetate 25 mg twice daily. The oestrone sulphate terminal elimination rate constant (lambda z) was concurrently increased (mean of 46 and 79%, respectively, with the 2 dosage regimens). A possible increase in oestrone sulphate clearance during long term treatment was tested for by injecting 6,7-[3H]-oestrone sulphate. These studies revealed a marked increase (mean 104%) in oestrone sulphate clearance in patients receiving the high dose aminoglutethimide schedule. Following injection of 4-[14C]-oestradiol plus 6,7-[3H]-oestrone sulphate, the fraction of 4-[14C]-oestradiol metabolised to oestrone sulphate was found to be reduced in all patients (mean 13%). A mean increase of 80% in the urinary excretion of 14C-oestriol was observed after 4-[14C]-oestradiol administration. Our results, although preliminary, suggest that aminoglutethimide is a potent inducer of aminoglutethimide metabolism, thereby producing a significant reduction in plasma bioavailability of oestrone sulphate. These effects may have a role in the action of aminoglutethimide, a finding which warrants further investigation.

Phosphorylation of the estradiol receptor in MCF-7 human breast cancer cells in culture.

Double labelling and Western blot techniques were used to demonstrate phosphorylation of estradiol receptor. Cells in monolayer culture were incubated with [32P]orthophosphate for 18 h followed by covalent whole cell labelling of the estradiol receptor with tritiated tamoxifen aziridine [( 3H]TA). Labelled receptor was precipitated with the monoclonal antibodies H222 or JS 34/32, coupled to protein A-Sepharose, and purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), or transferred to nitrocellulose paper. Receptor protein was detected on the Western blot with the monoclonal antibody H222 and rabbit anti-rat peroxidase conjugate. Phosphorylated receptor was visualized by autoradiography. Tritium and 32P activities were monitored in the gels. Two phosphorylated forms of the receptor (molecular weights 67 and 50 kDa) have been detected in MCF-7 cells. Estradiol treatment of the cells was found to increase phosphorylation of the receptor. In estradiol-treated cells both phosphorylated receptor forms were present mainly in the nuclear extract. Both forms bound [3H]TA as evidence by SDS-PAGE. [3H]TA binding was abolished by excess non-radioactive estradiol. In addition two phosphorylated proteins of approximately 120 and 90 kDa were regularly coprecipitated with receptor in cytosol. These proteins did not bind [3H]TA. The 90 kDa phosphorylated protein was identified as a heat shock protein (hsp-90).

Estradiol increases phosphorylation of the 90 kDa heat shock protein not associated with estradiol receptor in MCF-7 cells in culture.

MCF-7 cells in monolayer culture were incubated with [32P]orthophosphate for 18 h followed by covalent whole cell labelling of the estradiol receptor with tritiated tamoxifen aziridine [( 3H]TA). The heat shock protein (hsp-90) bound to receptor was precipitated with monoclonal antibodies H222 or JS 34/32, coupled to protein A-Sepharose and purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. Hsp-90 not associated with receptor was similarly purified after isolation with the monoclonal antibody AC88. It was found that estradiol treatment of the cells markedly increased phosphate incorporation in the free hsp-90, without affecting heat shock protein bound to receptor. A 6-fold increase in phosphate content was observed after 10 min incubation of the cells with estradiol. A similar effect was seen after treatment of the cells with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). The calcium ionophore A23187 had no influence on hsp-90 phosphorylation, and treatment of the cells with forskolin to increase the cellular content of cAMP had a reverse effect. A 50% reduction of the phosphate content in the free hsp-90 was observed after 15 min treatment. The observation that estradiol, TPA and forskolin had effect only on hsp-90 not bound to receptor is an indication that the receptor-hsp-90 complex exists in vivo. Time course studies show that the effect of estradiol is non-genomic. Two possible explanations of the results seem to exist. Either estradiol induces an increase in the degree of phosphorylation of hsp-90, or hsp-90 is translocated to the cytosol from a different cellular compartment.

Oestradiol treatment increases the sensitivity of MCF-7 cells for the growth stimulatory effect of IGF-I.

MCF-7 cells were grown in serum free medium (Dulbecco MEM without phenol red, supplemented with Costar SF-1 without insulin). Insulin was added as required and gave dose dependent growth stimulation at concentrations between 5 and 10,000 nM. Identical growth response curves were obtained for thymidine uptake and cell number. Oestradiol and insulin-like growth factor I (IGF-I) added individually both gave a dose dependent stimulation of cell growth in serum free medium containing 50 nM insulin. The growth stimulatory effect of oestradiol was to a large extent inhibited with suramine, a general inhibitor of growth factors, indicating that the effect of oestradiol was mediated through stimulating autocrine secretion of a growth factor. To investigate a possible link between the effects of oestradiol and IGF-I, a specific IGF-I receptor antibody (alpha IR-3), 10 micrograms/ml was used. These experiments were carried out with 2.5 nM insulin in the medium, a concentration at which insulin had no growth stimulatory effect. Stimulation was carried out for 18 h before assay of thymidine uptake. The effect of oestradiol was not significantly reduced by alpha IR-3, indicating that IGF-I was not an autocrine mediator of oestradiol stimulation of cell growth under these conditions, whereas alpha IR-3 extensively reduced growth stimulation by IGF-I. On long term stimulation (5 days) oestradiol had a marked stimulatory effect on cell number and alpha IR-3 almost totally abrogated this effect. When oestradiol (1 nM) and IGF-I (2.5 nM) were added together, the combined effect on thymidine incorporation and cell number was significantly greater than additive. This synergistic effect on the IGF-I growth response was totally abolished by the IGF-I receptor antibody. The results suggest a cooperative interaction of oestradiol and IGF-I. It is concluded that growth stimulation of MCF-7 cells by long term treatment with oestradiol may be mediated through autocrine secretion of IGF-I. the effect of short term stimulation of thymidine incorporation suggest that the growth response of oestradiol is more complex, and indicate that a cooperative interaction with IGF-I is involved, which is unrelated to stimulated autocrine secretion.

Nitrogen microbubbles induce a disappearance of single platelets (aggregation) with porcine platelets: a comparative study of the effects of anticoagulants and blood collection methods.

The pathogenesis of decompression illness (DCI) is uncertain. DCI involves all parts of the organism where gas bubbles are produced. They have both primary and secondary effects and have been classified as an agonist aggregating human platelets. In vitro effects of N2 bubbles on porcine platelets were investigated. Comparative studies using two different anticoagulants and three different sampling methods were performed. A disappearance of single platelets interpreted as platelet aggregation was observed in the presence of N2 bubbles in all studied groups. Aggregatory responses were more profound with platelets in heparinized plasma than in citrated plasma. In citrated plasma the aggregatory responses were more profound when blood was obtained from nonanaesthetized (awake) animals than from slaugtherhouse animals. Adrenaline (1 microM) had an inhibitory effect on N2 bubble induced platelet aggregation in vitro. The pig could be useful to investigate possible gas bubble effects in vivo.

Estrogen receptor in breast cancer; its relation to mean nuclear area, age and lymph node status.

A study of 378 patients with infiltrating breast carcinoma using linear logistic regression and ANOVA analysis demonstrated a different relation between age at operation and estrogen-receptor (ER) concentration in the lymph-node negative and the lymph-node positive groups. Tumours from patients between 51 and 70 years old had lower median ER concentration in the lymph-node negative group than in the lymph-node positive group. In the group older than 70 years, however, tumours from lymph-node negative patients had higher median ER concentrations than those from the lymph-node positive patients. Patients 50 years and younger had similar median ER concentrations in both lymph-node groups. Low mean nuclear area (MNA) of the tumour cells was associated with high frequency of tumours able to produce ER. No such association was found for age. Independent of age and lymph-node status tumours with low MNA also had high ER concentration. These findings suggest that tumours from different lymph-node/age groups may have different biological properties. The relationship between ER and nuclear size point to a key function of the nucleus, both as regards the ability to produce ER and its level of production.

Functional expression of horseradish peroxidase in E. coli by directed evolution.

In an effort to develop a bacterial expression system for horseradish peroxidase (HRP), we inserted the gene encoding HRP into the pET-22b(+) vector (Novagen) as a fusion to the signal peptide PelB. A similar construct for cytochrome c peroxidase (CcP) leads to high CcP activity in the supernatant. Expression of the wild-type HRP gene in the presence of isopropyl-beta-D-thiogalactopyranoside (IPTG) yielded no detectable activity against ABTS (azinobis(ethylbenzthiazoline sulfonate)). However, weak peroxidase activity was detected in the supernatant in the absence of IPTG. The HRP gene was subjected to directed evolution: random mutagenesis and gene recombination followed by screening in a 96-well microplate format. From 12 000 clones screened in the first generation, one was found that showed 14-fold higher HRP activity than wild-type, amounting to approximately 110 microg of HRP/L, which is similar to that reported from laborious in vitro refolding. No further improvement was obtained in subsequent generations of directed evolution. This level of expression has nonetheless enabled us to carry out further directed evolution to render the enzyme more thermostable and more resistant toward inactivation by H2O2. These results show that directed evolution can identify mutations that assist proteins to fold more efficiently in Escherichia coli. This approach will greatly facilitate efforts to "fine-tune" those many enzymes that are promising industrial biocatalysts, but for which suitable bacterial or yeast expression systems are currently lacking.

Extracellular proteins in breast tumor cytosol.

Several proteins have been quantitated in cytosols prepared from benign and malignant tumors of the breast; orosomucoid, albumin, transferrin, complement 4, C-reactive protein alpha 2-macroglobulin and hemoglobin. With the exception of hemoglobin, concentrations of the proteins measured were significantly intercorrelated. Their relative abundance was close to that reported in blood, except for alpha 2-macroglobulin and hemoglobin which were present in lower amounts. From hemoglobin measurements it can be concluded that blood contamination contributed less than 10% to the cytosol proteins measured. When compared to albumin, none of the proteins investigated occurred in concentrations sufficient to indicate local synthesis of a magnitude that would significantly influence tumor environment. From the present data it can be concluded that extracellular proteins constitute about 50% of total cytosol protein. This indicates an exceptional capillary leakage in breast tumors possibly related to abnormal hormonal influences. There were, however, large individual variations and about 10% of the cytosols could be predicted to contain negligible amounts of cell-derived protein. There was a highly significant difference between benign and malignant tumors in their cytosol content of extracellular protein, benign tumors containing nearly twice as much albumin. It is suggested that measurement of an extracellular protein (albumin) should be included in tumor characterization to correct for cellularity and representativity of tumor samples used for steroid receptor determinations and for measurements of other parameters using "cytosol" protein to express specific activity.