Association of circulating tumor DNA (ctDNA) tumor mutational burden (TMB) with DNA repair mutations and response to anti-PD-1/PD-L1 therapy in non-small cell lung cancer (NSCLC)

11537

Background: Identifying optimal biomarkers for response to anti-PD-1/PD-L1 therapies in NSCLC is critical. TMB is a potential biomarker of genomic instability and neoantigen binding sites to activated effector T cells. The goal of this study was to derive a measure of ctDNA TMB and to examine the association between TMB and clinical variables, DNA repair mutations, and response to checkpoint blockade. Methods: We retrospectively examined 136 patients with NSCLC who had undergone ctDNA next-generation sequencing (NGS) in our institution. The ctDNA testing, performed by Guardant360, is not currently clinically indicated for TMB. We derived ctDNA TMB using coding base substitutions and indel alterations both including and excluding potentially functional variants, but excluded rearrangements, fusions, and copy number variants. In addition, survival data were obtained for 17 patients who were treated with anti-PD-1/PD-L1 therapy and had ctDNA before first line therapy or within 90 days of therapy initiation. Results: ctDNA TMB was associated with the number of direct and indirect DNA repair gene mutations (t-test, p < 0.05). Smoking was also associated with higher TMB when including functional variants (chi-square test, p = 0.034). Driver mutations (EGFR, KRAS) and prior radiation therapy were not correlated with TMB. Lower ctDNA TMB (below the median, 15 mutations/MBp) was associated with longer PFS and OS (Kaplan-Meier log-rank test, p < 0.05). Conclusions: ctDNA TMB was derived and was significantly associated with greater number of DNA repair mutations. Smoking predicted higher TMB score. However, in a small subset of patients, lower ctDNA TMB predicted response to checkpoint blockade. Potential reasons include the small sample size, the possibility of ctDNA reflecting tumor burden, and the limited length of DNA sequenced (~78,000-138,000 bp). Larger, prospective studies are necessary to validate these findings.

Comparison of tumor mutational burden (TMB) across tumor tissue and circulating tumor DNA (ctDNA)

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Background: TMB is a potential biomarker for response to checkpoint blockade. Prior studies have associated tissue TMB with genomic instability and neoantigen binding sites for activated effector T cells. The goal of our study was to compare TMB in patients with paired next-generation sequencing (NGS) tests from tissue and ctDNA. Methods: Ninety-seven patients with NSCLC (N=53), breast cancer (N=34), and other solid tumors (N=10) with paired tissue (FoundationOne) and ctDNA (Guardant360, currently not clinically indicated for TMB) were examined retrospectively. Insufficient samples were eliminated (e.g., poor tissue quality or no mutations detected). TMB was compared using variants of unknown significance and synonymous mutations both with (N=74) and without potentially functional/driver variants (N=55). Results: Paired samples were compared using both continuous and binary TMB classifications (Table 1). TMB scores were significantly different using both comparisons (paired t-test, p<0.05). In addition, correlation coefficients between the two assays were low (Pearson Correlation, r=0.24-0.33). No significant differences were found based on timeframe between biopsies. Conclusions: This study demonstrated a lack of concordance between TMB for tissue and ctDNA in paired samples. Potential reasons include differences in sequencing length (~0.79-1.1 million bp for tissue vs. 78,000-138,000 bp for ctDNA), mutation detection, and methods of determining TMB. Future studies are warranted to determine whether ctDNA TMB can predict response to immunotherapy. [Table: see text]

Association of tumor mutational burden with smoking and mutation status in non-small cell lung cancer (NSCLC)

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Background: Reponses to immunotherapy have been observed in multiple solid tumors including non-small cell lung cancer (NSCLC). Identifying optimal biomarkers for response to anti-PD-1/PD-L1 therapies remains critical. Tumor mutational burden (TMB) may indicate genomic instability and potential neoantigen binding sites to activated effector T cells. Methods: We retrospectively examined tumor mutational burden (TMB) using next-generation sequencing (Foundation Medicine) for 83 patients with NSCLC in our institution. TMB included both coding and non-coding regions, but excluded potentially functional mutations. We correlated TMB (mutations per megabase) with smoking history, number of potentially functional mutations, variants of unknown significance, and the driver mutations EGFR, ALK, and KRAS. TMB high versus low was stratified based on 15 mutations per megabase pair. Results: Our findings demonstrated that TMB was significantly associated with current/former smoking status (p = 0.01, Table 1). TMB was also significantly associated with number of potentially functional mutations, number of variants of unknown significance (VUS), and total reported mutations (p < 0.01). The absence of mutations in EGFR, ALK, or KRAS tended to be associated with higher TMB as well (p = 0.07). Conclusions: TMB was associated with smoking status, as well as potentially functional mutations, VUS, and total number of reported mutations. Our results indicate that number of coding region mutations predict genomic instability in non-coding regions. Future studies are needed to correlate this measure with other immune biomarkers and patient outcome in NSCLC. [Table: see text]

Abstract 5233: Concordance of genomic alterations by next generation sequencing (NGS) in tumor tissue vs. cell-free DNA

Introduction:

Genomic analysis of circulating tumor cell-free DNA (cfDNA) represents a non-invasive method of assessing genomic alterations using peripheral blood. We compared the concordance between cfDNA and tissue biopsies across genomic alterations in 65 genes in this pilot retrospective study.

Methods:

54 consecutive patients with cfDNA NGS testing (Guardant360) were identified. Of these, 28 had tissue DNA NGS testing (Foundation One). 65 genes were common to both assays. Concordance was defined as the absence or presence of the identical genomic sequencing alteration(s) in a single gene. The analysis included non-synonymous DNA mutations, rearrangements, and copy number variants regardless of clone percentage.

Results:

There were 14 lung cancers and 14 other advanced solid tumors. Including all alterations and variants of unknown significance (VUS), the average number of alterations per patient for tissue and cfDNA was 4.82 (SD 3.02) and 2.96 (SD 3.01), respectively. Concordance between the two assays was 91.9%. Among only genes with reported genomic alterations in either assay (n = 170), concordance was 12.4%. Concordance was similar when stratifying based on timeframe between biopsies (median time interval between assays; 89 days). 21.5% of alterations found in tissue were detected in cfDNA. 34.9% of alterations found in cfDNA were detected in tissue. Across the 5 most common genes, sensitivity and specificity were 40.0% and 94.2%, respectively (Table 1).

Discussion:

Concordance between tumor tissue and cfDNA NGS was 91.9%. The cfDNA assay had high specificity, but low sensitivity. In addition, more mutations were detected in tissue. Reasons for these findings may include different sequencing techniques, spatial and temporal factors, tumor heterogeneity, and inclusion of subclones.

[AD and YC contributed equally.]

Table 1: Diagnostic Accuracy across 5 Most Common Genes Tissue MutationsSensitivity (%)Specificity (%)PPV (%)NPV (%)Diagnostic Accuracy (%)cfDNA mutations(+)(-)TP53(+)82(-)8850.080.080.050.057.1EGFR(+)12(-)22333.392.033.392.085.7KRAS(+)41(-)22166.795.580.091.389.3APC(+)01(-)4230.095.80.085.282.1CDKN2A(+)10(-)52216.7100.0100.081.582.1Total positive146Total negative2197Total (positive + negative)3510340.094.270.082.280.4

PPV: positive predictive value

NPV: negative predictive value

Citation Format: Young Kwang Chae, Andrew A. Davis, Benedito A. Carneiro, Sunandana Chandra, Nisha Mohindra, Aparna Kalyan, Jason Kaplan, Maria Matsangou, Leonidas C. Platanias, Massimo Cristofanilli, Francis J. Giles. Concordance of genomic alterations by next generation sequencing (NGS) in tumor tissue vs. cell-free DNA. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5233.

Biomarkers for PD-1/PD-L1 Blockade Therapy in Non-Small-cell Lung Cancer: Is PD-L1 Expression a Good Marker for Patient Selection?

Immunotherapy has emerged as a promising treatment modality in cancer therapy. With improved understanding of how to tip the balance of immune homeostasis, novel therapeutics targeting immune checkpoints have been developed, with durable responses observed in multiple solid tumors, including melanoma, renal cell carcinoma, and non-small-cell lung cancer. Clinical trials have reported favorable responses using programmed cell death-1 protein receptor (PD-1)/programmed cell death-1 protein ligand (PD-L1) blockade as monotherapy and most impressively in combinatorial trials with cytotoxic T-lymphocyte antigen-4 protein blockade. Nonetheless, a clinical benefit has not been observed in all patients. Therefore, identifying the ideal biomarkers for patient selection would be of great value in optimizing and personalizing immunotherapy. The utility of PD-L1 expression as a biomarker has varied in different clinical trials and immunohistochemistry assays. In addition, the response to immune checkpoint inhibition has been complicated by PD-L1 expression as a marker influenced by the dynamic tumor microenvironment. No consensus has yet been reached on whether PD-L1 expression is an ideal marker for patient selection. Recent research has shown promise for alternative markers, including T-cell immunohistochemistry, other immunologic markers, T-cell receptor clonality, and somatic mutational burden. However, additional studies are needed to assess the value of these as practical predictive biomarkers for patient selection and treatment response.

Immunotherapy for cancer in the central nervous system: Current and future directions

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults and still remains incurable. Although immunotherapeutic vaccination against GBM has demonstrated immune-stimulating activity with some promising survival benefits, tumor relapse is common, highlighting the need for additional and/or combinatorial approaches. Recently, antibodies targeting immune checkpoints were demonstrated to generate impressive clinical responses against advanced melanoma and other malignancies, in addition to showing potential for enhancing vaccination and radiotherapy (RT). Here, we summarize the current knowledge of central nervous system (CNS) immunosuppression, evaluate past and current immunotherapeutic trials and discuss promising future immunotherapeutic directions to treat CNS-localized malignancies.

Adenoid cystic carcinoma: current therapy and potential therapeutic advances based on genomic profiling

Adenoid cystic carcinoma (ACC) is a rare cancer with high potential for recurrence and metastasis. Efficacy of current treatment options, particularly for advanced disease, is very limited. Recent whole genome and exome sequencing has dramatically improved our understanding of ACC pathogenesis. A balanced translocation resulting in the MYB-NFIB fusion gene appears to be a fundamental signature of ACC. In addition, sequencing has identified a number of other driver genes mutated in downstream pathways common to other well-studied cancers. Overexpression of oncogenic proteins involved in cell growth, adhesion, cell cycle regulation, and angiogenesis are also present in ACC. Collectively, studies have identified genes and proteins for targeted, mechanism-based, therapies based on tumor phenotypes, as opposed to nonspecific cytotoxic agents. In addition, although few studies in ACC currently exist, immunotherapy may also hold promise. Better genetic understanding will enable treatment with novel targeted agents and initial exploration of immune-based therapies with the goal of improving outcomes for patients with ACC.

Optoporation and genetic manipulation of cells using femtosecond laser pulses

Femtosecond laser optoporation is a powerful technique to introduce membrane-impermeable molecules, such as DNA plasmids, into targeted cells in culture, yet only a narrow range of laser regimes have been explored. In addition, the dynamics of the laser-produced membrane pores and the effect of pore behavior on cell viability and transfection efficiency remain poorly elucidated. We studied optoporation in cultured cells using tightly focused femtosecond laser pulses in two irradiation regimes: millions of low-energy pulses and two higher-energy pulses. We quantified the pore radius and resealing time as a function of incident laser energy and determined cell viability and transfection efficiency for both irradiation regimes. These data showed that pore size was the governing factor in cell viability, independently of the laser irradiation regime. For viable cells, larger pores resealed more quickly than smaller pores, ruling out a passive resealing mechanism. Based on the pore size and resealing time, we predict that few DNA plasmids enter the cell via diffusion, suggesting an alternative mechanism for cell transfection. Indeed, we observed fluorescently labeled DNA plasmid adhering to the irradiated patch of the cell membrane, suggesting that plasmids may enter the cell by adhering to the membrane and then being translocated.

Metabolic syndrome and triple-negative breast cancer: a new paradigm

Triple-negative breast cancers (TNBCs) are aggressive tumors with poor prognosis compared to other breast cancer subtypes. The evidence linking TNBC with the metabolic syndrome, which consists of central obesity, insulin resistance, impaired glucose tolerance, dyslipidemia, and hypertension, has emerged from clinical studies and experiments using cell lines and mouse models. Epidemiological studies have associated abdominal obesity with increased incidence of TNBC. Additionally, insulin resistance, dyslipidemia, and hypertension are associated with increased incidence of breast cancer across all subtypes. The insulin-leptin-adiponectin axis has been implicated mechanistically in breast cancer tumorigenesis. Specifically, increased leptin and decreased adiponectin levels disrupt homeostatic signaling pathways involved in cell proliferation, survival, cell-cycle regulation, and angiogenesis. Insulin, insulin-like growth factor I (IGF-I), and epidermal growth factor receptor (EGFR) may mediate interactions between these two hormones. Further research will facilitate the development of targeted therapeutics and programs to modify lifestyle factors to modulate the insulin-leptin-adiponectin axis for TNBC.

Paraphilias in adult psychiatric inpatients

BACKGROUND

The goal of the present study was to examine the prevalence of paraphilias in an adult inpatient psychiatric population.

METHODS

One hundred twelve consecutive, voluntarily admitted, adult male psychiatric inpatients were administered the Structured Clinical Interview for DSM-IV, Sexual Disorders Module, Male Version, to assess the rates of DSM-IV paraphilias.

RESULTS

Fifteen patients (13.4%) reported symptoms consistent with at least one lifetime DSM-IV paraphilia. The most common paraphilias were voyeurism (n = 9 [8.0%]), exhibitionism (n = 6 [5.4%]), and sexual masochism (n = 3 [2.7%]). Patients who screened positive for a paraphilia had significantly more psychiatric hospitalizations (P = .006) and, on a trend level, were more likely to have attempted suicide. In addition, patients with paraphilias were significantly more likely to report having been sexually abused than patients without a paraphilia (P = <.001). Only 2 of the 15 paraphilic patients (13.3%) carried an admission diagnosis of a paraphilia.

CONCLUSIONS

Paraphilias appear to be more common in adult male psychiatric inpatients than previously estimated. The study also demonstrated that these disorders were not screened for by the treating physician and thus may go untreated. Further, larger-scale studies are necessary in order to further examine the rates of these disorders in the general population.

Symptom presentation and classroom functioning in a nonclinical sample of children with social phobia

This study investigates symptom presentation and school functioning in a nonclinical sample of children with social phobia (SP). Forty-five children with SP were identified via school-wide screenings and follow-up diagnostic interviews. Analyses examined types and intensity of fears, number of social situations avoided, interpersonal relationships, and classroom functioning. To identify characteristics unique to social phobic children, children with SP (n = 45) were compared to anxious children without SP (n = 56) on the above variables. Comorbidity in children with SP and factors associated with SP severity were also evaluated. Compared to anxious children without SP, children with SP feared and avoided a significantly greater number of social situations. In addition, they were significantly more likely to have trouble with making friends and to prefer being alone rather than with peers. All children with SP met criteria for at least one comorbid disorder. Significant factors explaining child-reported severity of SP were number of social situations avoided and intensity of fears. Greater severity of SP was significantly associated with poorer social skills, poorer leadership skills, greater attention difficulties, and greater learning problems in the classroom. It is important to understand the symptom presentation of SP so that children with SP are identified early and effective interventions are instituted. This is especially critical given the impact of SP on school functioning.

Metallothionein-3 and neuronal nitric oxide synthase levels in brains from the Tg2576 mouse model of Alzheimer's disease

Using antiserum against the recombinant isoform 3 of mouse brain metallothionein (MT3), the amount of MT3 protein was determined in whole brain homogenates from the Tg2576 transgenic mouse model of Alzheimer's Disease. Twenty-two month old transgenic positive mice showed a 27% decrease of MT3 normalized to the total protein in the extracts compared to same age, control transgenic negative mice. Metallothioneins bind seven molar equivalents of divalent metal ions per mole of protein so metal levels also were measured in these whole brain extracts using inductively coupled plasma atomic absorption (ICP-AA) spectrometry. No significant difference was observed for any metal assayed. Because neuronal nitric oxide synthase (nNOS) is involved in neurodegenerative disease and nitric oxide specifically interacts with MT3, the concentration and total nNOS activity also were evaluated. The transgenic positive mice showed a decrease of 28% in nNOS protein compared to the same age transgenic negative mice. Normalized to the amount of nNOS protein, total NOS activity was higher in the transgenic positive mice. These data showed that protein levels of both MT3 and nNOS were reduced in transgenic positive mice that show many characteristics of Alzheimer's Disease. In vitro studies suggested that MT3 was not a likely candidate for directly affecting nNOS activity in the brain.

The WldS protein protects against axonal degeneration: a model of gene therapy for peripheral neuropathy

The WldS mouse is a spontaneous mutant that is characterized by the phenotype of delayed degeneration of transected nerves (slow Wallerian degeneration). Molecular genetic analysis identified a mutation in this animal that codes for a unique protein expressed in brain tissue of WldS mice. We asked whether the WldS phenotype, in addition to delaying axonal degeneration after axotomy, might provide neuroprotection against toxic neuropathy. In dorsal root ganglia (DRG) cultures, neurites from WldS transiently exposed to vincristine not only resisted axonal degeneration but resumed growth after withdrawal of the toxin. Neurites from wild type mice died rapidly and did not recover. To prove that the identified mutation and its protein product are responsible for the WldS phenotype, we used an adenoviral gene transfer system to deliver the WldS to rat DRG neurons. Rat neurons expressing the WldS protein were resistant to vincristine-induced axonal degeneration, confirming the functional significance of the identified gene mutation. These data provide evidence that the WldS protein can be neuroprotective against vincristine neuropathy, and possibly other disorders characterized by axonal degeneration. In addition, delivery of this gene to wild type cells can transfer the WldS phenotype, providing the possibility of "gene therapy" for peripheral neuropathy.

Evaluation of travoprost as adjunctive therapy in patients with uncontrolled intraocular pressure while using timolol 0.5%

PURPOSE

To evaluate the intraocular pressure-lowering efficacy and safety of travoprost 0.0015% and 0.004%, dosed daily in the evening compared with vehicle, in patients with open-angle glaucoma or ocular hypertension, whose intraocular pressure was not adequately controlled on timolol 0.5% twice daily (twice daily).

METHODS

Subjects who qualified at screening began a run-in period dosing timolol twice daily for 3 weeks. If the subjects had an intraocular pressure of 24 to 36 mm Hg at 8 AM and 21 to 36 mm Hg at 10 AM and 4 pm in at least one eye on timolol, they were randomized to one of two concentrations of travoprost (0.0015% or 0.004%) or vehicle solution every day and were followed for 6 months. Four hundred twenty-six subjects were randomized. The mean intraocular pressure at 8 AM, 10 AM, and 4 PM in the patient's eye with the higher intraocular pressure was used for the analysis.

RESULTS

Mean baseline values (25 mm Hg) for subjects at eligibility (while maintained on timolol) were not significantly different (P <.0001) among the treatment groups. The intraocular pressure was lowered an additional -5.7 to -7.2 mm Hg and -5.1 to -6.7 mm Hg in the travoprost 0.004% and 0.0015% concentrations, respectively. These changes were significantly (P < or =.0001) different from the vehicle group (-1.3 to -2.8 mm Hg). The intraocular pressure range on treatment at all visit times over the 6-month treatment period ranged from 17.9 to 19.2 mm Hg for travoprost 0.004% and 18.3 to 20.1 mm Hg for travoprost 0.0015% compared with 22.4 to 24.1 mm Hg for vehicle. Average hyperemia scores ranged from trace to mild (mean 0.5 on a scale of 0 = none/trace; 1= mild; 2 = moderate; 3 = severe) for all treatment groups. No iris pigmentation changes were observed in any patient during this study. There were no clinically or statistically significant changes from baseline in visual acuity, ocular cells and flare, fundus parameter, cup-to-disk ratio and visual field between the treatment groups. There were no serious adverse events reported for any treatment group.

CONCLUSIONS

Travoprost produced clinically relevant and statistically significant additional intraocular pressure reductions from baseline when used adjunctively with timolol in subjects with open-angle glaucoma or ocular hypertension.

Travoprost compared with latanoprost and timolol in patients with open-angle glaucoma or ocular hypertension

PURPOSE

This study evaluated the safety and intraocular pressure-lowering efficacy of two concentrations of travoprost (0.0015% and 0.004%) compared with latanoprost 0.005% and timolol 0.5% in patients with open-angle glaucoma or ocular hypertension.

METHODS

Eight hundred one patients with open-angle glaucoma or ocular hypertension were randomly assigned to travoprost 0.0015%, travoprost 0.004%, latanoprost 0.005%, or timolol 0.5%. The efficacy and safety of travoprost (0.0015% and 0.004%) daily was compared with latanoprost daily and timolol twice daily for a period of 12 months.

RESULTS

Travoprost was equal or superior to latanoprost and superior to timolol with mean intraocular pressure over visits and time of day ranging from 17.9 to 19.1 mm Hg (travoprost 0.0015%), 17.7 to 19.1 mm Hg (travoprost 0.004%), 18.5 to 19.2 mm Hg (latanoprost), and 19.4 to 20.3 mm Hg (timolol). For all visits pooled, the mean intraocular pressure at 4 PM for travoprost was 0.7 mm Hg (0.0015%, P =.0502) and 0.8 mm Hg (0.004%, P =.0191) lower than for latanoprost. Travoprost 0.004% was more effective than latanoprost and timolol in reducing intraocular pressure in black patients by up to 2.4 mm Hg (versus latanoprost) and 4.6 mm Hg (versus timolol). Based on a criterion of 30% or greater intraocular pressure reduction from diurnal baseline or intraocular pressure 17 mm Hg or less, travoprost 0.0015% and 0.004% had an overall response to treatment of 49.3% and 54.7%, respectively, compared with 49.6% for latanoprost and 39.0% for timolol. Iris pigmentation change was observed in 10 of 201 of patients (5.0%) receiving travoprost 0.0015%, six of 196 of patients (3.1%) receiving travoprost 0.004%, 10 of 194 of patients (5.2%) receiving latanoprost, and none of the patients receiving timolol (0 of 196). The average ocular hyperemia score was less than 1 on a scale of 0 to 3, indicating that on average patients experienced between none/trace and mild for all treatment groups. There were no serious, unexpected, related adverse events reported for any therapy.

CONCLUSIONS

Travoprost (0.0015% and 0.004%), a highly selective, potent prostaglandin F (FP) receptor agonist, is equal or superior to latanoprost and superior to timolol in lowering intraocular pressure in patients with open-angle glaucoma or ocular hypertension. In addition, travoprost 0.004% is significantly better than either latanoprost or timolol in lowering intraocular pressure in black patients. Travoprost is safe and generally well tolerated in the studied patient population.

Timing of CNS cell generation: a programmed sequence of neuron and glial cell production from isolated murine cortical stem cells

Multipotent stem cells that generate both neurons and glia are widespread components of the early neuroepithelium. During CNS development, neurogenesis largely precedes gliogenesis: how is this timing achieved? Using clonal cell culture combined with long-term time-lapse video microscopy, we show that isolated stem cells from the embryonic mouse cerebral cortex exhibit a distinct order of cell-type production: neuroblasts first and glioblasts later. This is accompanied by changes in their capacity to make neurons versus glia and in their response to the mitogen EGF. Hence, multipotent stem cells alter their properties over time and undergo distinct phases of development that play a key role in scheduling production of diverse CNS cells.

Activin A promotes progenitor differentiation into photoreceptors in rodent retina

Activins are TGF beta-like proteins that were first discovered for their actions on the reproductive system, but have subsequently been shown to play a role in a variety of developmental processes. Previous studies have demonstrated that activins and their receptors are present in the developing retina, as well as other regions of the embryonic nervous system. We used both in vitro and in vivo approaches to test for functions of activin during retinal development. We found that activin A treatment of embryonic day 18 rat retinal cultures causes the progenitor cells in the cultures to exit the cell cycle and differentiate into rod photoreceptors. This effect is dose-dependent and the promotion of rod photoreceptor differentiation is specific, since the other primary retinal neurons generated in these cultures, the C1+ amacrine cells, are not affected by activin A treatment. Mice with homozygous deletion of the activin betaA gene show a specific decrease in the number of rod photoreceptors compared to wild-type or heterozygous littermates. These data demonstrate that activin A is an important regulator of photoreceptor differentiation in the developing retina.

HSF1 is required for extra-embryonic development, postnatal growth and protection during inflammatory responses in mice

HSF1 is the major heat shock transcriptional factor that binds heat shock element (HSE) in the promoter of heat shock proteins (Hsps) and controls rapid Hsp induction in cells subjected to various environmental stresses. Although at least four members of the vertebrate HSF family have been described, details of their individual physiological roles remain relatively obscure. To assess whether HSF1 exhibited redundant or unique in vivo functions, we created Hsf1(-/-) deficient mice. We demonstrate that homozygous Hsf1(-/-) mice can survive to adulthood but exhibit multiple phenotypes including: defects of the chorioallantoic placenta and prenatal lethality; growth retardation; female infertility; elimination of the 'classical' heat shock response; and exaggerated tumor necrosis factor alpha production resulting in increased mortality after endotoxin challenge. Because basal Hsp expression is not altered appreciably by the HSF1 null mutation, our findings suggest that this factor, like Drosophila Hsf protein, might be involved in regulating other important genes or signaling pathways. Our results establish direct causal effects for the HSF1 transactivator in regulating critical physiological events during extra-embryonic development and under pathological conditions such as sepsis to modulate pro-inflammatory responses, indicating that these pathways have clinical importance as therapeutic targets in humans.

Transcriptional regulation of cellular retinaldehyde-binding protein in the retinal pigment epithelium. A role for the photoreceptor consensus element

Cellular retinaldehyde-binding protein (CRALBP) is abundantly expressed in the retinal pigment epithelium (RPE) and Muller cells of the retina, where it is thought to function in retinoid metabolism and visual pigment regeneration. Mutations in human CRALBP that destroy retinoid binding have been linked to autosomal recessive retinitis pigmentosa. To identify the DNA elements that regulate expression of the human CRALBP gene in the RPE, transient transfection studies were carried out with three CRALBP-expressing human RPE cell culture systems. The regions from -2089 to -1539 base pairs and from -243 to +80 base pairs demonstrated positive regulatory activity. Similar activity was not observed with cultured human breast, liver, or skin cells. Since sequence analysis of the -243 to +80 region identified the presence of two photoreceptor consensus element-1 (PCE-1) sites, elements that have been implicated in photoreceptor gene regulation, the role of these sequences in RPE expression was examined. Mutation of either PCE-1 site significantly reduced reporter activity, and mutation or deletion of both sites dramatically reduced activity. Electrophoretic mobility shift analysis with RPE nuclear extracts revealed two complexes that required intact PCE-1 sites. These studies also identified two identical sequences (GCAGGA) flanking PCE-1, termed the binding CRALBP element (BCE), that are also important for complex formation. Southwestern analysis with PCE-1/BCEcontaining probes identified species with apparent masses near 90-100 and 31 kDa. These results begin to identify the regulatory regions required for RPE expression of CRALBP and suggest that PCE-1-binding factor(s) may play a role in regulating RPE as well as photoreceptor gene expression.

FGF2 concentration regulates the generation of neurons and glia from multipotent cortical stem cells

The embryonic cerebral cortex contains a population of stem-like founder cells capable of generating large, mixed clones of neurons and glia in vitro. We report that the default state of early cortical stem cells is neuronal, and that stem cells are heterogeneous in the number of neurons that they generate. In low fibroblast growth factor (FGF2) concentrations, most maintain this specification, generating solely neuronal progeny. Oligodendroglial production within these clones is stimulated by a higher, threshold level of FGF2, and astrocyte production requires additional environmental factors. Because most cortical neurons are born before glia in vivo, these data support a model in which the scheduled production of cortical cells involves an intrinsic neuronal program in the early stem cells and exposure to environmental, glia-inducing signals.

A human retinal pigment epithelial cell line that retains epithelial characteristics after prolonged culture

PURPOSE

A spontaneously arising, apparently transformed, cell line has been cloned from a primary culture of human retinal pigment epithelial (RPE) cells and has been subcultured more than 200 times. The similarities of these cells to human RPE cells in vivo have been determined.

METHODS

The structure of the transformed cells has been determined by light and electron microscopy and by immunocytochemistry using antibodies that detect cytoskeletal and other proteins. The ability of the cell line to bind and phagocytose photoreceptor material has also been assessed by fluorescence and electron microscopy. The metabolism of all-trans-retinol has been investigated by incubation of the cells with 3H-all-trans-retinol and analysis of the metabolic products by high-performance liquid chromatography.

RESULTS

The transformed cells possess an epithelial cobblestone morphology with intercellular junctional complexes containing N-cadherin. The cytoskeleton of these cells comprises cytokeratins that are characteristic of epithelial cells, together with actin, spectrin, and vimentin. The keratins expressed are those typical of RPE cells. The cells also express cellular retinaldehyde binding protein and retinol dehydrogenase activity but do not express retinoid isomerase or lecithin retinol acyl transferase activities. These cells also exhibit phagocytic activity.

CONCLUSIONS

This cell line retains many of the metabolic and morphologic characteristics of RPE cells in vivo although there are some differences, particularly the loss of some enzymatic activities and cytoskeletal polarization. These cells should be useful in further studies of RPE cell metabolism and other functions.

A self-renewing multipotential stem cell in embryonic rat cerebral cortex

Neuroectoderm cells in the cortical ventricular zone generate many diverse cell types, maintain the ventricular zone during embryonic life and create another germinal layer, the subventricular zone, which persists into adulthood. In other vertebrate tissues, including skin, intestine, blood and neural crest, stem cells are important in maintaining a germinal population and generating differentiated progeny. By following the fates of single ventricular zone cells in culture, we show here that self-renewing, multipotential stem cells are present in the embryonic rat cerebral cortex. Forty per cent of these stem cells produced all three principal cell types of the central nervous system: neurons, astrocytes and oligodendrocytes. Stem cells constituted about 7% of cortical clones; in contrast, over 80% consisted of small numbers of neurons or glia. We suggest that multipotential stem cells may be the ancestors of other cortical progenitor cells that exhibit more limited proliferation and more restricted repertoires of progeny fates.

Characterization of marine prokaryotic communities via DNA and RNA

We know very little about species distributions in prokaryotic marine plankton. Such information is very interesting in its own right, and ignorance of it is also beginning to hamper process studies, such as those on viral infection. New DNA- and RNA-based approaches avoid many prior limitations. Here we discuss four such applications: (1) cloning and sequencing of 16S rRNA genes to produce lists of what types of organisms are present; (2) quantification of these individual types in marine samples by nucleic acid hybridization, including single cell fluorescence; (3) quantitative comparison by DNA-DNA hybridization of entire microbial communities in terms of shared common types, without knowledge of community components; and (4) finding cultures that are representative of native communities. Several previously uncharacterized types of bacteria and archaea (probably including novel phyla) are present in marine plankton. Evidence from both the Atlantic and Pacific suggests that as-of-yet uncultivated archaea may dominate the deep sea, and thus may be the most abundant group of organisms on Earth. Such archaea are in surface waters as well, and can be visualized with fluorescent probes and enriched at room temperature with addition of organic nutrients. Community hybridization shows that variability of microbial community compositions in time and space is high. Although most native bacteria do not grow in culture, some proteobacterial cultures appear by genomic hybridization to be representative of certain communities. These and other results indicate the utility of DNA- and RNA-based methods.

Isolated rat cortical progenitor cells are maintained in division in vitro by membrane-associated factors

Ventricular zone cells in the developing CNS undergo extensive cell division in vivo and under certain conditions in vitro. The culture conditions that promote cell division have been studied to determine the role that contact with cell membrane associated factors play in the proliferation of these cells. Progenitor cells have been taken from the ventricular zone of developing rat cerebral cortex and placed into microwells. Small clusters of these cells can generate large numbers of neurons and non-neuronal progeny. In contrast, single progenitor cells largely cease division, approximately 90% acquiring neuron-like characteristics by 1 day in vitro. DiI-labeled, single cells from embryonic day 14 cortex plated onto clusters of unmarked progenitor cells have a significantly higher probability (approximately 3-fold) of maintaining a progenitor cell phenotype than if plated onto the plastic substratum around 100 microns away from the clusters. Contact with purified astrocytes also promotes the progenitor cell phenotype, whereas contact with meningeal fibroblasts or balb3T3 cells promotes their differentiation. Membrane homogenates from cortical astrocytes stimulate significantly more incorporation of BrdU by E14 cortical progenitor cells than membrane homogenates from meningeal fibroblasts. These data indicate that the proliferation of rat cortical progenitor cells can be maintained by cell-type specific, membrane-associated factors.

Bilateral facet dislocation at the lumbosacral joint. A report of a case and review of literature

Traumatic facet dislocation of the lumbosacral joint is uncommon. This report of a bilateral L5-S1 facet dislocation is compared with prior reported unilateral and bilateral cases with respect to mechanism of injury, neurologic injury, surgical reduction and fixation, and clinical outcome. Attention to the disk injury is recognized as essential to prevent cauda equina or root compression after reduction and fixation of the dislocation.

Transferrin is made and bound by photoreceptor cells

Retinal pigment epithelial cells, which form one aspect of the blood-retinal barrier, control the access of blood-borne components such as diferric transferrin to the neural retina. It has recently been shown that RPE cells remove iron from diferric transferrin in a low pH compartment and subsequently release it in a low molecular weight form that can be chelated by apo-transferrin (Hunt and Davis: J. Cell Physiol. 152:102-110, 1992). It is now shown that photoreceptor cells can bind diferric transferrin to receptors on their inner segments. Moreover, polymerase chain reaction and in situ hybridization show that cells of the neural retina, particularly photoreceptors, make apo-transferrin.

Phylogenetic diversity of subsurface marine microbial communities from the Atlantic and Pacific Oceans

The extent of the diversity of marine prokaryotes is not well known, primarily because of poor cultivability. However, new techniques permit the characterization of such organisms without culturing, via 16S rRNA sequences obtained directly from biomass. We performed such an analysis by polymerase chain reaction amplification with universal primers on five oligotrophic open-ocean samples: from 100-m (three samples) and 500-m depths in the western California Current (Pacific Ocean) and from a 10-m depth in the Atlantic Ocean near Bermuda. Of 61 clones, 90% were in clusters of two or more related marine clones obtained by ourselves or others. We report 15 clones related to clone SAR 11 found earlier near Bermuda (S. J. Giovannoni, T. B. Britschgi, C. L. Moyer, and K. G. Field, Nature [London] 345:60-63, 1990), 11 related to marine cyanobacteria, 9 clustered in a group affiliated with gram-positive bacteria, 9 in an archaeal cluster we recently described (mostly from the 500-m sample), 4 in a novel gamma-proteobacterial cluster, and 6 in three two-membered clusters (including other archaea). One clone was related to flavobacteria. Only the cyanobacteria plus one other clone, related to Roseobacter denitrificans (formerly Erythrobacter longus Och114), were within 10% sequence identity to any previously sequenced cultured organism in a major data base. We never found more than two occurrences of the same sequence in a sample, although four times we found identical sequences between samples, two of which were between oceans; one of these sequences was also identical to SAR 11.(ABSTRACT TRUNCATED AT 250 WORDS)

Release of iron by human retinal pigment epithelial cells

Retinal pigment epithelial cells, which form one aspect of the blood-retinal barrier, take up iron in association with transferrin by a typical receptor-mediated mechanism (Hunt et al., 1989. J. Cell Sci. 92:655-666). This iron is dissociated from transferrin in a low pH environment and uptake is sensitive to agents that inhibit endosomal acidification. The dissociated iron enters the cytoplasm as a low molecular weight (less than 10 kD) component and subsequently binds to ferritin. No evidence for recycling of iron in association with transferrin was found. Nevertheless, much of the iron that is taken up is recycled to the extracellular medium, primarily from the low molecular weight pool. This release of iron is not sensitive to inhibitors of energy production or of vesicular acidification but is increased up to a maximum of about 40% of the total 55Fe incorporated when cells are incubated with serum or the medium is changed. When a short loading time for 55Fe from 55Fe-transferrin is used (i.e., when the low molecular weight pool is proportionately larger), a much larger fraction of the cell-associated radiolabel is released than when longer loading times are used. The data suggest that a releasable intracellular iron pool is in equilibrium with the externalized material. The released iron may be separated into a high and a low molecular weight component. The former is similar on polyacrylamide gel electrophoresis to ferritin although it cannot be immune precipitated by anti-ferritin antibodies. The low molecular weight 55Fe which is heterogeneous in nature can be bound by external apo-transferrin and may represent a form that can be taken up by cells beyond the blood-retinal barrier.

Novel major archaebacterial group from marine plankton

Marine bacteria often dominate the plankton biomass and are responsible for much of the cycling of organic matter, but bacterial diversity is poorly understood because conventional identification methods (requiring culturing) miss about 99% of the organisms. Recent advances permit characterization of microbial communities by analysis of 16S ribosomal RNA gene sequences directly from biomass without the need to culture the organisms; such studies from surface ocean samples have found only eubacteria, not archaebacteria (or Archaea), which are profoundly different. Here we report 16S rRNA sequences obtained from Pacific Ocean bacterioplankton samples collected from depths of 100 m and 500 m. Among these we found sequences only distantly related to those of any organisms previously characterized by 16S rRNA sequences, with similarities to the nearest such relatives (extreme thermophiles) approximately the same as those between animals and plants. We suggest that these sequences are from a previously undescribed archaebacterial group that may have diverged from the ancestors of characterized organisms very early in evolution.

Sciatica: Treating a Painful Symptom

In brief Contrary to popular belief, sciatica, a symptom of lumbar disk herniation, is relatively uncommon. Characteristics include pain in the posterior thigh, lower leg, or foot that is greater than accompanying low-back pain. Sciatic tension tests confirm the presence of sciatica by reproducing the pain. Many patients who have sciatica recover spontaneously; most others can be treated conservatively with limitation of activity, anti-inflammatory medication, and gradual return to full activity. A variety of surgical options are available for patients who have extruded disks and progressive neurologic deficit or severe, persistent, intolerable pain.

Selective inhibition of growing pigment epithelial cells by a receptor-directed immunotoxin

An immunotoxin conjugate of a murine monoclonal antibody against human transferrin receptors and the A chain of ricin was examined for its potential to inhibit selectively the growth of retinal pigment epithelial (RPE) cells which grow in an uncontrolled manner in proliferative vitreoretinopathy. The probable efficacy of such an agent in vivo stems from the observation that actively proliferating cells possess many more transferrin receptors than normal quiescent cells. The authors showed in vitro that the immunoconjugate (454A12 MAB-rRA) inhibits protein synthesis in actively dividing RPE cells but has a smaller or no effect on protein synthesis by confluent, nondividing RPE cells. The effect was specific in that neither the free ricin A chain (rRA) nor the monoclonal antibody (454A12 MAB) alone has any inhibitory effect. Furthermore, the antibody competes with the immunotoxin and suppresses the latter's toxicity. This immunotoxin has applications for therapy in conditions in which the pathologic proliferation of RPE cells occurs.

Altered expression of keratin and vimentin in human retinal pigment epithelial cells in vivo and in vitro

Actively proliferating human retinal pigment epithelial (RPE) cells grown in tissue culture possess keratin-containing intermediate filaments that react with a combination of AE1 and AE3 anti-keratin monoclonal antibodies. Antibody reactivity is lost, however, from RPE cells as the cell population ceases to proliferate when it approaches confluence and attains morphological characteristics more similar to those in vivo. In contrast, clone 8.13 anti-keratin antibody stains all cells in the culture at all stages of the growth cycle and cell densities. These findings were reflected in vivo using retinal pigment epithelium taken directly from the eye. Normal non-proliferating RPE cells bound 8.13 antibody to cytoskeletal structures, as judged by indirect immunofluorescence, but did not bind AE1/AE3 antibodies. However, proliferating dedifferentiated RPE cells from the vitreous humor of patients with proliferative vitreoretinopathy possess filaments that bind both AE1/AE3 and 8.13 antibodies. Thus it appears that structures detected by AE1/AE3 antibodies only occur in actively growing RPE cells in vitro and in vivo. Keratins produced by RPE cells were identified using Western blotting. Species with molecular masses of 54 (keratin 7), 52 (keratin 8), 42 (keratin 18), and 40 (keratin 19) kiloDaltons were the most abundant in proliferating cultured cells, but cells isolated directly from the eye were found to lack keratin 7 and 19. Keratin 19 was, however, observed in proliferating RPE cells from some patients with proliferative vitreoretinopathy. The latter findings explain the differential staining observed with AE1/AE3 antibodies in cells in culture and isolated directly from the eye since these antibodies interact primarily with keratin 19 which is absent from non-proliferating RPE cells. In contrast to the presence of keratin-containing intermediate filaments in human RPE cells in vivo, there are apparently no detectable vimentin-containing cytoskeletal structures. However, all RPE cells cultured in vitro develop filaments composed of vimentin which persist in cells that have reached confluence.

Changes in glycosylation alter the affinity of the human transferrin receptor for its ligand

When transferrin receptors of human erythroleukemic cells were pulse-labeled with [35S]methionine and then chased in the absence of radioactive precursor, the first detectable immunoprecipitable form of the receptor had a molecular mass of 85 kDa. This form of the receptor was converted to the mature form of 93 kDa with a half-time of about 40-60 min. Both the immature (85 kDa) and mature (93 kDa) receptors associated as dimers, the native form of the receptor. The 85-kDa, as well as the 93-kDa, receptors bound to a monoclonal antibody raised against the transferrin receptor or to transferrin-Sepharose. In order to determine whether glycosylation was necessary for ligand binding, purified receptors were isolated from cells grown in the presence of tunicamycin. When K562 cells were grown in the presence of tunicamycin, an 80-kDa nonglycosylated form of the receptor was synthesized. This nonglycosylated receptor was also capable of dimer formation; however, much less of it reached the cell surface than the fully glycosylated form, although both untreated and tunicamycin-grown cells appeared to synthesize transferrin receptors at similar rates. Although the number of receptor molecules/cell was similar in control and tunicamycin-treated cells, the nonglycosylated receptors exhibited a much lower affinity for transferrin than those of untreated cells; in contrast, when receptors were purified by immunoprecipitation and digested with bacterial alkaline phosphatase, no difference was observed between the affinity of these receptors and undigested immunoprecipitated receptors. These results suggest that glycosylation is not necessary for specific binding of transferrin to its receptor, but the affinity of this binding can be influenced greatly by the presence or absence of carbohydrate residues.

Transferrin receptors on the surfaces of retinal pigment epithelial cells are associated with the cytoskeleton

Retinal pigment epithelial cells, derived from human donor eyes, have been grown in culture as monolayers on membrane filters or plastic surfaces and shown to possess transferrin receptors with a monomeric molecular mass of 93,000. These receptors internalize 125I-labelled transferrin and recycle it to the surrounding medium in a similar manner to other cell types. Scatchard analyses show that there are about 100,000 high-affinity receptors on the surface of each cell and most of these receptors are associated with the cytoskeleton. In total cell extracts, there are additional low-affinity binding sites that do not appear to be strongly associated with the cytoskeleton. The apparent interaction of transferrin receptors with the cytoskeleton was confirmed in two ways: first, using 200 kV electron microscopy for stereo analyses, skeleton-associated transferrin receptors were detected by a monoclonal anti-receptor antibody and a colloidal gold-conjugated second antibody after Triton X-100 extraction of pigment epithelial cells grown directly on laminin-coated gold grids; and, second, when cell surface receptors were labelled with radioiodinated transferrin and then incubated for various periods of time, the labelled transferrin was observed to move from a Triton X-100-insoluble fraction (a putative cytoskeletal compartment) to a Triton-soluble compartment that was not associated with the cytoskeleton. Using either horseradish peroxidase or colloidal gold-labelled transferrin, it has been shown that basolateral and apical surface-located receptors participate in receptor-mediated endocytosis via clathrin-coated pits, endosomes and tubular structures. Initially, transferrin internalized from the apical surface is observed in small endosomes that often appear to be embedded in an apical layer of microfilaments. From these peripheral regions of the cells, the labelled receptors move to larger endosomes and multivesicular bodies deeper in the cytoplasm. These structures have no apparent association with cytoskeletal elements.

Twelve years of clinical experience with lithium pulse generators

The clinical performance of 9,651 lithium pulse generators, which were implanted at our registry hospitals since 1973, was assessed by analysis of actuarial survival data and information obtained at the time of pacemaker failure. Cumulative survival estimates for all units were: 5 years, 94 percent, 7 years, 81 percent, 10 years, 62 percent. Discriminant actuarial analysis revealed no differences between lithium iodine and lithium cupric sulfide longevity. Battery depletion was found in 49.1 percent of 277 units subjected to detailed explant analysis, while 31 percent and 8.7 percent had component and hermetic seal defects, respectively. Of the pulse generators with battery depletion, all but two units exhibited normal end-of-battery life behavior. We conclude that the lithium iodine and lithium cupric sulfide batteries are safe, long-term energy sources; however, the impact of reduced battery size and dual chamber pacing on these performance parameters is unknown.

"Montrose" Child Life Protection Unit: a treatment and assessment model in child abuse intervention

In New South Wales, Australia, the Department of Youth and Community Services is empowered by statute to deal with cases of child abuse and neglect. Its child protection services include the Montrose Child Life Protection Unit which is designed to support and complement the work of both the Intake Service, Field Service and most importantly the work of child protective facilities in the community. The service has intake crisis counselling and call out resources; maintains a central register; provides a facility for crisis residential care for children and families, diagnostic assessment, and a day programme. The emphasis in service delivery in New South Wales in the area of child protection is on multidisciplinary intervention. The Department of Youth and Community Services is involved in promoting interagency cooperation and co-ordination. Over and above a philosophy that underlies service delivery is the Montrose Unit's involvement in sensitising the community to the difficult and often demanding role of parenting. Montrose represents an attempt to create an environment where parenting myths can be examined from a reality base and strategies implemented for reeducation.

One hundred and eighty-seven cases of child abuse and neglect

The case histories of 187 abused and neglected children, admitted to the Royal Alexandra Hospital for Children over a three-year-period, were reviewed. Multiproblem families from the lower socioeconomic groups predominated, reflecting the hospital's geographic catchment area. Eight children died and 30 were made state wards. A high proportion of mothers described problems during the pregnancy, a difficult delivery and neonatal problems. The majority of parents in this study were married and had small families. First-born male infants of young isolated mothers were found to be at greatest risk of child abuse and neglect.