Abstract P1-09-02: Prevalence of genetic mutations in patients with second primary breast cancers

Background: Women newly diagnosed with primary breast cancer (PBC) often undergo multi-gene panel testing to determine their contralateral breast cancer (BC) risk and whether a contralateral prophylactic mastectomy is warranted. However, with the exception of BRCA1/2, gene-specific associations with contralateral or second PBC (SPBC) have not been established. Methods: The study sample was comprised of 83,278 women with BC referred to a single diagnostic laboratory for multi-gene panel testing. The frequency of pathogenic/likely pathogenic variants in clinically-actionable genes (CAG), including highly penetrant genes (HPG: BRCA1, BRCA2, TP53, PTEN) and moderately penetrant genes (MPG: ATM, CHEK2, PALB2, CDH1, NBN, NF1) was compared between women with a PBC and SPBC. Women with a SPBC <1 year from their first diagnosis were excluded. Logistic regression burden tests were used to test for associations between mutated genes and SPBC adjusting for age at diagnosis of first BC, histology, presence of first- or second-degree relative with BC, and race/ethnicity. Results: The study included 75,550 women with PBC and 7,728 with SPBC. The median (IQR) time between primaries for the SPBC group was 11 (6,17) years . Women with SPBC were slightly more likely to be Caucasian (67.8% vs. 63.4%; p<0.001), older when referred for genetic testing (mean difference 9.7 years, p<0.001), slightly younger at first BC diagnosis (mean difference 2.1 years, p<0.001) and slightly more likely to have >1 first or second degree relative with BC (62.2% vs. 60.8%; p=0.004) than PBC. Among women tested for all CAGs, 4,883 (8.1%) were carriers of pathogenic/likely pathogenic variants (11.1% SPBC vs. 7.8% PBC). CHEK2 was the most frequently mutated gene (3.4% SPBC vs. 2.3% PBC), followed by BRCA1 (2.7% SPBC vs.1.6% PBC), BRCA2 (2.2% SPBC vs. 1.8% PBC), and PALB2 (1.4% SPBC vs. 0.9% PBC). In fully adjusted models, women with SPBC were 1.38 times as likely (p=<0.0001) as women with PBC to test positive for a CAG (OR=1.35 for HPG and 1.34 for MPG). BRCA1 (OR=1.49; p<0.0001), followed by CHEK2 (OR=1.36; p<0.0001) and PALB2 (OR=1.53; p<0.001) were most significantly associated with SPBC. TP53, BARD1, ATM and BRCA2 were marginally associated with SPBC (p=0.01 to 0.06). When results were stratified by race/ethnicity, ORs among Caucasians were similar to those observed overall. Among African Americans, women with SPBC were 1.76 times as likely to carry a CAG (p<0.001) than their PBC counterparts. PALB2 (OR=2.69; p=0.002), BRCA2 (OR=1.85; p=.004), and TP53 (OR=3.88; p=.009) were most significantly associated with SPBC followed by BRCA1 (OR=1.63; p=.002). Analysis of gene associations for other racial/ethnic groups was limited by small sample size. Conclusions: There is a significantly higher prevalence of CAG mutations among women with SPBC, even after adjusting for age at diagnosis and family history. These findings support SPBC as a standalone indication for multigene panel testing. Additional studies aimed to assess cumulative risk of SPBC for CAG beyond BRCA1/2 are needed to help guide clinical management decisions for mutation carriers.

Citation Format: Yao K, Clifford J, Li S, LaDuca H, Hulick PJ, Xu J, Gutierrez S, Black MH. Prevalence of genetic mutations in patients with second primary breast cancers [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-09-02.

Forced expression of a constitutively active form of Stat3 in mouse epidermis enhances malignant progression of skin tumors induced by two-stage carcinogenesis

Recently, our laboratory demonstrated that Stat3 is required for the de novo development of chemically-induced skin tumors. We have further investigated the role of Stat3 in epithelial carcinogenesis using mice in which the expression of a constitutively active/dimerized form of Stat3 (Stat3C) is targeted to the proliferative compartment of epidermis (referred to as K5.Stat3C transgenic mice). Keratinocytes from K5.Stat3C mice showed increased survival following exposure to 7,12-dimethylbenz[a]anthracene (DMBA) and enhanced proliferation following exposure to 12-O-tetradecanoylphorbol-13-acetate (TPA). In two-stage chemical carcinogenesis experiments using DMBA as the tumor initiator and TPA as the promoter, K5.Stat3C mice developed skin tumors with a shorter latency and in much greater number compared to non-transgenic littermates. Remarkably, 100% of the skin tumors that developed in K5.Stat3C transgenic mice bypassed the premalignant stage and were initially diagnosed as carcinoma in situ which rapidly progressed to squamous cell carcinoma (SCC). These tumors were highly vascularized, poorly differentiated and invasive and loss of expression of K10, filaggrin and E-cadherin was observed by 20 weeks. Finally, overexpression of Stat3C in a papilloma cell line led to enhanced cell migration and enhanced invasion through Matrigel in both the absence and presence of growth factors. In addition to its critical role in early stages of epithelial carcinogenesis, the current study reveals a novel role for Stat3 in driving malignant progression of skin tumors in vivo.

Radiostrontium contamination of soil and vegetation within the Semipalatinsk test site

The Semipalatinsk nuclear test site (STS) in the Republic of Kazakhstan was an important site for testing atomic bombs and other civil and military nuclear devices of the former Soviet Union. Results are presented from investigations on the extent of radiostrontium contamination in soils and vegetation at the technical areas of the STS, where the tests were conducted and in pastures used by farmers for grazing animals or for hay production. Our data are compared with those reported largely in the recent Russian language literature that has been reviewed. The extent of (90)Sr contamination of soil is highly variable over the STS with the highest values associated with the technical areas, particularly the Degelen mountains. Recently measured values in both the present data and the Russian language literature confirm the relatively high current contamination of soil and vegetation in the vicinity of tunnels and associated watercourses in the Degelen area. The proportion of (90)Sr in soil which could not be extracted with 6 M HCl was only an average of 20%, which is low compared to other test site areas and possibly indicates a relatively high mobility in this area, because the (90)Sr is derived from leakage from explosion tunnels along watercourses rather than being associated with fused silicates. A comparison of relative activity concentrations in soil and vegetation suggests that the transfer of (90)Sr to vegetation on the STS is high compared to that of (137)Cs and plutonium.

USDA options for regulatory changes to enhance the prevention and control of avian influenza

During the past decade, several examples of the ability of H5 and H7 low-pathogenicity avian influenza (LPAI) viruses to mutate to high-pathogenicity (HP) viruses have been documented worldwide. During this time, the introduction and persistence of an H7N2 LPAI virus in the northeast live-bird marketing system in the United States has raised concern on how to prevent the possibility of such a mutation occurring in this country. The United States has periodically experienced trade restrictions based on the occasional introduction of H5 and H7 LPAI viruses into commercial poultry and based on AI-related changes in the import requirements for poultry and poultry products of several of our trading partners. Consequently, the U.S. Department of Agriculture (USDA) is exploring options for how our regulatory response to H5 and H7 LPAI viruses might be revised to better protect our domestic poultry flocks from HPAI and to ensure that any interruptions in trade are scientifically supportable. The options under consideration include mandatory and voluntary measures to improve the surveillance for and control of H5 and H7 LPAI virus infections.

Genetic and environmental contributions to loneliness in children

This report presents the results of the first behavioral genetic studies of children's loneliness. Data were collected using both an adoption design and a twin-sibling design. As part of the Colorado Adoption Project, 133 sibling pairs (69 biologically related pairs and 64 unrelated pairs in adoptive families) completed a general loneliness scale when they were 9, 10, 11, and 12 years old. As part of the San Diego Sibling Study, 142 sibling pairs (22 monozygotic twin, 40 dizygotic twin, and 80 full-sibling pairs) between the ages of 8 and 14 years old completed a scale assessing loneliness at school. Both studies showed significant heritability and nonshared environmental influences for children's loneliness.

Nursing leaders predict top trends for 2000

Nursing Management's Editorial Advisory Board predicts the top 10 trends that will impact nurse leaders in 2000. Use them to lead in the new millennium.

Distal scaphoid resection arthroplasty for the treatment of degenerative arthritis secondary to scaphoid nonunion

Nineteen patients with chronic scaphoid nonunion and associated degenerative arthritis between the distal fragment and the radial styloid were treated by resection of the distal fragment. All patients had a dorsal intercalated segment instability wrist collapse pattern with an average radiolunate angle of -32 degrees and a 10% reduction in the carpal height, both of which changed minimally during the follow-up period. The duration of the nonunion averaged 12 years and the follow-up period averaged 49 months. Range of motion improved 85% and grip improved 134%. Thirteen of the patients experienced complete pain relief. One patient required additional surgery and elected wrist arthrodesis. Resection of the distal fragment is not recommended for patients with capitolunate arthritis. Two of the 4 patients with capitolunate arthritis had persistent symptoms; 3 had progressive degenerative changes.

Giving voice to childbearing teens: views on sexuality and the reality of being a young parent

Interpretive phenomenology was the qualitative research approach used to explore the lived experience of teenage mothers in regard to their sexuality and associated development, decision making, relationships, and hopes for the future. Several interviews were conducted with each of nine low-income, African-American teen mothers over the course of several months. This paper presents narrative exemplars from the lives of these teenage mothers gathered during interviews in the school nurse's office. Exemplars were: Sand Castles: the unreliability of support systems; Tough Boys, Soft Hearts: feeling less powerless with a strong male; Erosion of Trust: the deterioration of trusted kin networks; and Staying the Course: the intergenerational nature of adolescent pregnancy. Intervention and prevention implications for school nurses and other school professionals are suggested based on the findings.

Altered expression of selectable marker URA3 in gene-disrupted Candida albicans strains complicates interpretation of virulence studies

The ura-blaster technique for the disruption of Candida albicans genes has been employed in a number of studies to identify possible genes encoding virulence factors of this fungal pathogen. In this study, the URA3-encoded orotidine 5'-monophosphate (OMP) decarboxylase enzyme activities of C. albicans strains with ura-blaster-mediated genetic disruptions were measured. All strains harboring genetic lesions via the ura-blaster construct showed reduced OMP decarboxylase activities compared to that of the wild type when assayed. The activity levels in different gene disruptions varied, suggesting a positional effect on the level of gene expression. Because the URA3 gene of C. albicans has previously been identified as a virulence factor for this microorganism, our results suggest that decreased virulence observed in strains constructed with the ura-blaster cassette cannot accurately be attributed, in all cases, to the targeted genetic disruption. Although revised methods for validating a URA3-disrupted gene as a target for antifungal drug development could be devised, it is clearly desirable to replace URA3 with a different selectable marker that does not influence virulence.

Specific and redundant functions of retinoid X Receptor/Retinoic acid receptor heterodimers in differentiation, proliferation, and apoptosis of F9 embryonal carcinoma cells

We have generated F9 murine embryonal carcinoma cells in which either the retinoid X receptor (RXR)alpha and retinoic acid receptor (RAR)alpha genes or the RXRalpha and RARgamma genes are knocked out, and compared their phenotypes with those of wild-type (WT), RXRalpha-/-, RARalpha-/-, and RARgamma-/- cells. RXRalpha-/-/ RARalpha-/- cells were resistant to retinoic acid treatment for the induction of primitive and parietal endodermal differentiation, as well as for antiproliferative and apoptotic responses, whereas they could differentiate into visceral endodermlike cells, as previously observed for RXRalpha-/- cells. In contrast, RXRalpha-/-/RARgamma-/- cells were defective for all three types of differentiation, as well as antiproliferative and apoptotic responses, indicating that RXRalpha and RARgamma represent an essential receptor pair for these responses. Taken together with results obtained by treatment of WT and mutant F9 cells with RAR isotype- and panRXR-selective retinoids, our observations support the conclusion that RXR/ RAR heterodimers are the functional units mediating the retinoid signal in vivo. Our results also indicate that the various heterodimers can exert both specific and redundant functions in differentiation, proliferation, and apoptosis. We also show that the functional redundancy exhibited between RXR isotypes and between RAR isotypes in cellular processes can be artifactually generated by gene knockouts. The present approach for multiple gene targeting should allow inactivation of any set of genes in a given cell.

Distinct retinoid X receptor-retinoic acid receptor heterodimers are differentially involved in the control of expression of retinoid target genes in F9 embryonal carcinoma cells

The F9 murine embryonal carcinoma cell line represents a well-established system for the study of retinoid signaling in vivo. We have investigated the functional specificity of different retinoid X receptor (RXR)-retinoic acid (RA) receptor (RAR) isotype pairs for the control of expression of endogenous RA-responsive genes, by using wild-type (WT), RXR alpha(-/-), RAR alpha(-/-), RAR gamma(-/-), RXR alpha(-/-)-RAR alpha(-/-), and RXR alpha(-/-)-RAR gamma(-/-) F9 cells, as well as panRXR and RAR isotype (alpha, beta, and gamma)-selective retinoids. We show that in these cells the control of expression of different sets of RA-responsive genes is preferentially mediated by distinct RXR-RAR isotype combinations. Our data support the conclusion that RXR-RAR heterodimers are the functional units transducing the retinoid signal and indicate in addition that these heterodimers exert both specific and redundant functions on the expression of particular sets of RA-responsive genes. We also show that the presence of a given receptor isotype can hinder the activity of another isotype and therefore that functional redundancy between retinoid receptor isotypes can be artifactually generated by gene knockouts.

Influence of diet and exercise on skeletal muscle and visceral adipose tissue in men

The effects of diet only (DO) and diet combined with either aerobic (DA) or resistance (DR) exercise on subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), lean tissue (LT), and skeletal muscle (SM) tissue were evaluated in 33 obese men (DO, n = 11; DA, n = 11; DR, n = 11). All tissues were measured by using a whole body multislice magnetic resonance imaging (MRI) model. Within each group, significant reductions were observed for body weight, SAT, and VAT (P < 0.05). The reductions in body weight (approximately 10%) and SAT (approximately 25%) and VAT volume (approximately 35%) were not different between groups (P > 0.05). For all treatments, the relative reduction in VAT was greater than in SAT (P < 0.05). For the DA and DR groups only, the reduction in abdominal SAT (approximately 27%) was greater (P < 0.05) than that observed for the gluteal-femoral region (approximately 20%). Conversely, the reduction in VAT was uniform throughout the abdomen regardless of treatment (P > 0.05). MRI-LT and MRI-SM decreased both in the upper and lower body regions for the DO group alone (P < 0.05). Peak O2 uptake (liters) was significantly improved (approximately 14%) in the DA group as was muscular strength (approximately 20%) in the DR group (P < 0.01). These findings indicate that DA and DR result in a greater preservation of MRI-SM, mobilization of SAT from the abdominal region, by comparison with the gluteal-femoral region, and improved functional capacity when compared with DO in obese men.

Two distinct actions of retinoid-receptor ligands

Signalling by all-trans retinoic acid is mediated through RXR-RAR retinoid receptor heterodimers, in which RXR has been considered to act as a transcriptionally silent partner. However, we show here that in cultured NB4 (ref. 6) human acute promyelocytic leukaemia cells treated with either an RAR-alpha-selective agonist alone, or certain RAR-alpha antagonists in combination with an RXR agonist, receptor-DNA binding is induced in vivo, resulting in expression of the target genes of retinoic acid as well as acute promyelocytic leukaemia protein (PML) relocation to nuclear bodies and differentiation before apoptosis. These results indicate that RAR-alpha ligands can induce two separate events: one enables RXR-RAR-alpha heterodimers to bind to DNA in vivo and allows RXR agonists to act; the other induces transcriptional activity of RAR-alpha. The availability of receptor-specific synthetic retinoids that can induce distinct receptor functions has potential in extending the therapeutic repertoire of retinoids.

RXRalpha-null F9 embryonal carcinoma cells are resistant to the differentiation, anti-proliferative and apoptotic effects of retinoids

The F9 murine embryonal carcinoma (EC) cell line, a well established model system for the study of retinoic acid (RA)-induced differentiation, differentiates into cells resembling three types of extra-embryonic endoderm (primitive, parietal and visceral), depending on the culture conditions and RA concentration used. A number of previously identified genes are differentially expressed during this process and serve as markers for the different endodermal cell types. Differentiation is also accompanied by a decreased rate of proliferation and an apoptotic response. Using homologous recombination, we have disrupted both alleles of the retinoid X receptor (RXR) alpha gene in F9 cells to investigate its role in mediating these responses. The loss of RXRalpha expression impaired the morphological differentiation of F9 EC cells into primitive and parietal endoderm, but has little effect on visceral endodermal differentiation. Concomitantly the inducibility of most primitive and parietal endoderm differentiation-specific genes was impaired, while several genes upregulated during visceral endodermal differentiation were induced normally. We also demonstrate that RXRalpha is required for both the anti-proliferative and apoptotic responses in RA-treated F9 cells. Additionally, we provide further evidence that retinoic acid receptor (RAR)-RXR heterodimers are the functional units transducing the effects of retinoids in F9 cells.

Establishing an interdisciplinary patient care team: collaboration at the bedside and beyond

The authors describe how an interdisciplinary team used skills in communication and collaboration to improve patient care on a busy surgical service. A major goal was to establish and maintain continuity of care in the face of decreasing lengths of stay and increasing patient acuity. The authors share their insight about designing and supporting a successful interdisciplinary patient care team and discuss how their experiences relate to concepts such as case management and career development.

Process and outcomes in general practice consultations: problems in defining high quality care

In order to explore the relationships between the verbal interactions of the consultation and several outcomes (patient health change, patient compliance and the satisfaction of both doctor and patient), 21 General Practitioners contributed ten audiotaped consultations each, from consecutive consenting adult patients. The effects of GP sex and postgraduate training were also investigated, but were found to be minimal. Patient health change was most clearly related to acuteness of symptoms at presentation, whereas reported compliance was predicted by patient satisfaction after the consultation. Different consultations were maximally satisfying for doctors and for patients, and patient and doctor satisfaction with specific consultations showed little correlation. This result implies that the measurement of quality of care, in general practice at least, is a more complex task than has been assumed, and in turn raises issues about whose definition of outcome is relevant in discussing quality of care.

Conditional site-specific recombination in mammalian cells using a ligand-dependent chimeric Cre recombinase

We have developed a strategy to generate mutant genes in mammalian cells in a conditional manner by employing a fusion protein, Cre-ER, consisting of the loxP site-specific Cre recombinase linked to the ligand-binding domain of the human estrogen receptor. We have established homozygous retinoid X receptor alpha-negative (RXR alpha-/-) F9 embryonal carcinoma cells constitutively expressing Cre-ER and have shown that estradiol or the estrogen agonist/antagonist 4-hydroxytamoxifen efficiently induced the recombinase activity, whereas no activity was detected in the absence of ligand or in the presence of the antiestrogen ICI 164,384. Furthermore, using a targeting vector containing a selection marker flanked by loxP sites, we have inactivated one retinoic acid receptor alpha allele in such a line, demonstrating that the presence of the recombinase does not inhibit homologous recombination. Combining this conditional site-specific recombination system with tissue-specific expression of Cre-ER may allow modification of the mammalian genome in vivo in a spatiotemporally regulated manner.

What do experienced GPs really need in communication skills training?

In studying the connections between the verbal interactions in general practice consultations and outcomes such as patient and doctor satisfaction, the authors developed an interest in the various sources of occupational stress for Australian GPs. Doctors and their patients do not necessarily agree about how satisfactory a consultation was, raising questions about whose definition of quality in medical care should prevail. Doctors' concerns about exceeding the Health Insurance Commission (HIC) norms for frequency and length of consultations seemed to inhibit them from providing the listening time some patients need. Complexity of consultations proved difficult to rate reliably. Experienced GPs in a preceptor role expressed mixed feelings about the value of communication skills training compared with changes in remuneration policies. We seek comment from readers about these observations.

Sources of occupational stress for Australian GPs, and their implications for postgraduate training

Following a study of process and outcomes in general practice consultations, we returned to the GP participants and asked them to comment on taped consultations which they had found unsatisfying. Their comments were then analysed for information about sources of occupational stress, coping strategies, and this method of self-monitoring. About two-thirds of the stressors which they described arose from their interaction with the patient, and the rest from sources either internal to the doctor or else external to the particular doctor and consultation. The subjects' comments about their coping techniques, and their acceptance of this method of self-monitoring, in conjunction with the findings about sources of occupational stress provide a basis for planning vocational education in general practice.

RAR beta isoforms: distinct transcriptional control by retinoic acid and specific spatial patterns of promoter activity during mouse embryonic development

That both deficiency and excess of vitamin A lead to a wide spectrum of congenital abnormalities has strongly implicated the active metabolite, retinoic acid (RA), in normal embryonic development. There are 3 families of RA receptors (RARs), RAR alpha, RAR beta and RAR gamma, each having at least two isoforms derived from primary transcripts initiated at two promoters P1 and P2 (reviewed in Leid et al., 1992) Transcripts encoding all 4 isoforms of RAR beta (RAR beta 1 to RAR beta 4) accumulate in embryonal carcinoma (EC) cells in the presence of RA. It has been previously shown that the RA modulation of RAR beta 2/beta 4 transcripts is achieved at the level of transcriptional initiation via a RA response element (RARE) present in the P2 RAR beta 2/beta 4 promoter. In contrast, the mechanism by which RA up-regulates RAR beta 1/beta 3 transcripts has not yet been elucidated. We describe here the isolation of the P1 RAR beta 1/beta 3 promoter and characterization of its activity in transgenic animals. We find that RAR beta 1/beta 3 promoter activity, which is apparently confined to the embryonic CNS, is not modified by RA treatment, unlike that of the RAR beta 2/beta 4 promoter (Mendelsohn et al., 1991). Nuclear run-on transcription analysis in EC cells supports the conclusion that RAR beta 1/beta 3 transcript initiation is not modulated by RA, and that the RA-induced accumulation of RAR beta 1/beta 3 transcripts occur via a RA-dependent release of a block in RNA chain elongation.

Determining medical necessity of outpatient physical therapy services

A patient referred for physical therapy may attend one or several therapy visits or may continue to receive ongoing therapy services several times weekly for several months. The question of the continued medical necessity of those services arises often. Determination of medical necessity for continued therapy services requires knowledge of the natural history of diseases that may require therapy services, familiarity with the effectiveness of treatment alternatives for those diseases, and awareness of community practice patterns. Accurate and complete documentation from the therapist or referring physician is required for the physician advisor or utilization review consultant to make an accurate determination of medical necessity. A structured format for providing this documentation is suggested.

Age-associated changes in the circadian rhythm of retinal N-acetylserotonin and melatonin in rats with pigmented eyes

Using a semiquantitative immunohistochemical procedure, we have evaluated the 24 hour circadian rhythm of N-acetylserotonin- and melatonin-like immunoreactivity in the retina of male hooded rats that have pigmented eyes. Three and twenty months old Long Evans rats were used. Animals were kept under a 14 light (L): 10 dark (D) lighting cycle and were sacrificed during the month of June. Four time points were assessed in the 24 hour light/dark cycle. Retinal N-acetylserotonin and melatonin were assessed by immunohistochemistry and microphotometric procedures as previously used by us. In young animals, the intensity of retinal N-acetylserotonin and melatonin immunofluorescence was significantly different (P less than 0.005, DF = 17) in animals killed during the light vs the dark period with peak values during the dark period. In contrast, retinal N-acetylserotonin and melatonin-immunofluorescence in old animals showed a flattened 24 hour rhythm, with light values as high as those observed during the dark period. The age-associated bluntness of the 24 hour rhythm was more noticeable for N-acetylserotonin than for melatonin immunofluorescence.

The effect of fenclofenac on thyroid function

The non-steroidal anti-inflammatory agent fenclofenac competitively inhibits the binding of thyroxine(T4) and triiodothyronine (T3) by thyroxine-binding globulin(TBG). Eight male volunteers completed a 4-week study during which they took fenclofenac 600 mg twice daily. The concentration of fenclofenac in serum reached a plateau after 1 week of therapy after which the mean concentration(+/SEM) of the drug in serum was 78.6 o.2 mg/1. During the steady state period on treatment there were reductions of the mean serum concentrations of total T4 to 35% (P less than 0.001), total T3 to 55% (P less than 0.001), free T4 to 69% (P less than 0.001) and free T3 to 90% (NS) of the respective pretreatment values. There were also significant changes in the concentrations of thyrotropin and reverse T3 in serum. After starting treatment with fenclofenac serum concentrations of thyrotrophin fell to a nadir after 2-4 days at which time the mean concentration was 34% (P less than 0.01) of the pretreatment value, whilst reverse T3 values increased to a maximum of 136% (P less than 0.001) of the pretreatment values over 1-2 days. There was subsequently an increase of the thyrotrophin and a reduction in reverse T3 concentrations to normal by 2 weeks of pretreatment. Transient pituitary suppression was also suggested by the response to to thryotrophin-releasing hormone (TRH): 7 days after starting fenclofenac the mean thyrotrophin response was 62% (P less than 9.001) of the pretreatment value. After 4 weeks of fenclofenac the response of TRH had returned to normal. After discontinuing fenclofenac there was a transient increase in the mean concentration of thyrotrophin in serum, to 129% of the pretreatment value (P less than 0.001), with a subsequent return to normal. Four weeks after discontinuing fenclofenac the serum concentrations of thyroid hormones and thyrotrophin were normal.

The effects of surfactants on cell aggregation

Trypsin-dissociated HeLa and human amnion cells were employed to investigate the effects of an anionic, a cationic, and a non-ionic surfactant on cell reaggregation. All the surfactants inhibited the reaggregation process, the effect increasing with surfactant concentration, and becoming significant at concentrations of about 10(−6) M for the anionic surfactant and about 10(−5) M for the others. The effects of temperature and ionic strength on HeLa cell aggregation, and of surfactants on the electrophoretic mobility of HeLa cells and the release of sialic acid from their surfaces by neuraminidase, were also examined. The results indicate that although electrostatic effects occur and are likely to be of importance in cell reaggregation, the effect of surfactants cannot be accounted for on this basis alone, and it is suggested that interactions involving the cell-surface glycoproteins, possibly indirectly via effects on the fluidity of the cell membrane, are also significant in this respect.