Filaggrin mutations in relation to skin barrier and atopic dermatitis in early infancy

BACKGROUND

Loss-of-function mutations in the skin barrier gene filaggrin (FLG) increase the risk of atopic dermatitis (AD), but their role in skin barrier function, dry skin and eczema in infancy is unclear.

OBJECTIVES

To determine the role of FLG mutations for impaired skin barrier function, dry skin, eczema and AD at three months of age and through infancy.

METHODS

FLG mutations were analyzed in 1836 infants in the Scandinavian population-based PreventADALL study. Transepidermal water loss (TEWL), dry skin, eczema and AD were assessed at three, six and 12 months of age.

RESULTS

Filaggrin mutations were observed in 166 (9%) infants. At three months, carrying FLG mutations was not associated with impaired skin barrier function (TEWL > 11.3 g/m² /h) or dry skin, but with eczema (OR(95%CI): 2.76 (1.81, 4.23), p < 0.001). At six months, mutation carriers had significantly higher TEWL than non-mutation carriers (mean (95%CI) 9.68 (8.69, 10.68) vs. 8.24 (7.97, 8.15), p < 0.01) and at three and six months an increased risk of dry skin on truncus (OR: 1.87 (1.25, 2.80), p = 0.002; 2.44 (1.51, 3.95), p < 0.001) or extensor limb surfaces (1.52 (1.04, 2.22), p = 0.028; 1.74 (1.17, 2.57), p = 0.005). FLG mutations were associated with eczema and AD in infancy.

CONCLUSION

Filaggrin mutations were not associated with impaired skin barrier function or dry skin in general at three months of age, but increased the risk for eczema, as well as for dry skin on truncus and extensors at three and six months.

Exploring reasons for overuse of contralateral prophylactic mastectomy in Canada

Background

Contralateral prophylactic mastectomy (cpm) in women with known unilateral breast cancer (bca) has been increasing despite the lack of supportive evidence. The purpose of the present study was to identify the determinants of cpm in women with unilateral bca.

Methods

This qualitative descriptive study used semi-structured interviews informed by the Theoretical Domains Framework. We interviewed 74 key informants (surgical oncologists, plastic surgeons, medical oncologists, radiation oncologists, nurses, women with bca) across Canada. Interviews were analyzed using thematic analysis and an analysis for shared and discipline-specific beliefs.

Results

In total, 58 factors influencing the use of cpm were identified: 26 factors shared by various health care professional groups, 15 discipline-specific factors (identified by a single health care professional group), and 17 factors shared by women with unilateral bca. Health care professionals identified more factors discouraging the use of cpm (n = 26) than encouraging its use (n = 15); women with bca identified more factors encouraging use of cpm (n = 12) than discouraging its use (n = 5). The factor most commonly identified by health care professionals that encouraged cpm was lack of awareness of existing evidence or guidelines for the appropriate use of cpm (n = 44, 75%). For women with bca, the factor most likely influencing their decision for cpm was wanting a better esthetic outcome (n = 14, 93%).

Conclusions

Multiple factors discouraging and encouraging the use of cpm in unilateral bca were identified. Those factors identify potential individual, team, organization, and system targets for behaviour change interventions to reduce cpm.

Abstract P3-07-08: Multi-omic predictor of rapid and late relapse in primary triple negative breast cancer

Background: Triple-negative breast cancer (TNBC) is a heterogeneous disease. Clinically, we observe three distinct TNBC outcomes: 1) rapid relapse (rrTNBC) characterized by aggressive drug resistant disease; 2) late relapse (lrTNBC) characterized by indolent or treatment responsive disease; and 3) no relapse (NoRTNBC). We hypothesized that distinct clinical and genomic features of primary tumors define rapid versus late relapse in TNBC.

Approach: Using three publicly-available datasets (METABRIC, TCGA, and a prior gene expression meta-analysis), we identified 455 patients diagnosed with primary TNBC with adequate follow-up to be characterized as rrTNBC (relapse or death within 2 years of diagnosis), lrTNBC (relapse or death more than 2 years after diagnosis), or NoRTNBC (no relapse/death with at least 5 years follow-up). We compiled basic clinical (n=455 patients) and primary tumor multi-omic data, including whole transcriptome (n=455), whole genome copy number (n=317), and mutation data for 171 cancer-related genes (n=317). We evaluated intrinsic subtypes (PAM50, TNBCtype), 125 gene expression signatures, CIBERSORT immune subsets, copy number, and mutation frequency.

Results: We first evaluated patients with relapse (rrTNBC+lrTNBC) vs. NoRTNBC. There was no significant difference in age, grade, stage at diagnosis, or PAM50 or TNBC subtype proportion between relapse and NoRTNBC. Among 125 expression signatures, five immune signatures were significantly higher in NoRTNBCs (FDR p&lt;0.05) suggesting increased immune activity in patients who do not relapse. Using CIBERSORT inferred immune subsets, anti-tumor CD8 T-cell, M1 macrophage, and gamma-delta T-cell subsets were all highly correlated to these immune signatures (all Pearson's r &gt;= 0.3, all p&lt;1.2e-8). Among genomic features, patients who relapsed were significantly more likely to harbor a mutation in PIK3CA (Fisher exact FDR p=0.02) but there was no significant difference in tumor mutation burden or percent genome altered (Student's t-test p=0.83 and p=0.99, respectively). We then evaluated primary TNBC genomic data in patients who ultimately developed rapid vs. late relapse. Patients with rrTNBC were more likely to be higher stage (p&lt;0.0001) while lrTNBC were more likely to be non-basal PAM50 subtype (p=0.03). Among 11 significantly altered gene expression signatures (FDR p&lt;0.05), 6 estrogen/luminal signatures were significantly higher in lrTNBC. Mutations in DNAH11 and PIK3CA were more common in lrTNBC (Fisher exact FDR p=0.04 and p=0.05, respectively) but there were no significant differences in tumor mutation burden or copy number burden (Student's t-test p=0.13 and p=0.45, respectively). Using 317 cases with full genomic data divided into training and validation datasets, we will report a comparison of machine learning models for predicting relapse versus no relapse and rapid versus late relapse.

Conclusions: Primary TNBC tumors destined for rapid, late, or no relapse reflect distinct genomic features. Anti-tumor immune signatures and subsets are enriched in patients who do not relapse yet no difference in mutational or copy number burden. Relative to rapid relapse TNBCs, late relapse TNBCs are enriched for non-basal tumors, estrogen/luminal expression signatures, and mutations in DNAH11 and PIK3CA.

Citation Format: Zhang Y, Nock W, Asad S, Adams E, Singh J, Damicis A, Lustberg MB, Noonan A, Reinbolt R, Sardesai S, VanDeusen J, Wesolowski R, Williams N, Ramaswamy B, Stover DG. Multi-omic predictor of rapid and late relapse in primary triple negative breast cancer [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 P3-07-08.

Abstract P1-09-01: CD8+ T-cell gene expression and signatures in breast cancer and adjacent normal breast tissue: Association with body mass index, alcohol intake, and age at diagnosis

Background: Our understanding of mediators of immune infiltration in breast cancer and normal breast tissue remains limited. We hypothesize that patient factors known to be associated with inflammation and immune subsets, including body mass index, alcohol intake, and age and diagnosis, may play an important role in the tumor-immune microenvironment. Analyses of immune gene expression and signatures facilitate interrogation of the immune microenvironment in large patient cohorts.

Methods: Participants from the Nurses' Health Study cohorts I and II diagnosed with invasive breast cancer were included. Total RNA extracted and microarray performed for 882 tumor and 695 tumor-adjacent samples, of which 623 tumors have matched tumor-adjacent data. CD8+ T-cell expression metrics were assessed: CD8A single gene expression (CD8Agene), a CD8 T-cell signature (CD8sig), and a tumor infiltrating lymphocyte signature derived from the GeparSixto clinical trial (GSAct). Standard clinicopathologic features were evaluated, as well as body mass index (BMI) one year prior to diagnosis, cumulative average alcohol intake, and age at diagnosis.

Results: Overall, tumor and adjacent normal tissue demonstrated positive correlation of CD8Agene, CD8sig, and GSAct (n=623 pairs, Pearson's r = 0.46, 0.36, 0.31, respectively; all p&lt;0.001). Similar correlations were present in TCGA breast cancer, an independent cohort (n=112 pairs, Pearson's r = 0.34, 0.17, 0.45, respectively; all p&lt;0.001). We evaluated paired tumor and adjacent normal samples within individual immunohistochemical (IHC) subtype or PAM50 subtype by Wilcoxon signed-rank test. There was not a consistent trend for CD8Agene, CD8sig, nor GSAct to be greater in tumor or normal within subtypes. We then evaluated patient features/exposures and tumor immune expression metrics. For tumor-adjacent normal, there was no significant association of alcohol intake, BMI, or age at diagnosis with CD8 gene/expression metrics. For tumor tissue, a multivariate model demonstrated that BMI one year before diagnosis was significantly associated with CD8Agene expression. There was no significant association of alcohol intake or age at diagnosis with CD8 gene/expression metrics. We are currently evaluating the association of these CD8 T-cell gene expression signatures with CD8 T-cell immunohistochemistry in a subset of patients, which will be reported at the time of abstract presentation.

Conclusion: In this cohort of over 600 tumor:normal pairs and a separate validation cohort, multiple distinct CD8+ T-cell expression metrics are correlated between breast cancer and tumor-adjacent normal breast tissue. This suggests that the adjacent normal breast may reflect an altered immune microenvironment in the context of breast cancer. While age at diagnosis and alcohol intake are not significantly associated with tumor CD8 expression metrics, BMI was significantly associated with tumor CD8Agene expression in a multivariate model.

Citation Format: Damicis A, Heng YJ, Kensler K, Asad S, Adams E, Singh J, Zhang Y, Nock W, Wesolowski R, Williams N, Reinbolt R, Sardesai S, VanDeusen J, Noonan A, Lustberg MB, Ramaswamy B, Eliassen AH, Hankinson SE, Tamimi R, Stover DG. CD8+ T-cell gene expression and signatures in breast cancer and adjacent normal breast tissue: Association with body mass index, alcohol intake, and age at diagnosis [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 P1-09-01.

Abstract P4-01-17: Aggressive subgroups of metastatic triple-negative breast cancer: Inflammatory breast cancer and young patients in the Dana-Farber cell-free DNA cohort

Background: Relative to other metastatic breast cancer subtypes, metastatic triple-negative breast cancer (mTNBC) has a shorter duration of response to therapy and worse overall survival. Within mTNBCs, there is a prevailing belief that inflammatory breast cancer and young women tend to have among the most aggressive phenotypes. We investigated clinical and cell-free DNA (cfDNA) characteristics of inflammatory-mTNBC and young-mTNBC. We hypothesized that inflammatory-mTNBC may have distinct clinical and cfDNA characteristics, offering potential novel biomarker and therapeutic strategies.

Methods: 164 patients from the Dana-Farber metastatic triple-negative cell-free DNA cohort (Stover DG, et al J Clin Oncol 2018) were included in this secondary analysis. Patients were stratified into three groups: 1) inflammatory breast cancer ('IBC'); 2) non-IBC patients aged 45 years (yr) or younger at primary diagnosis ('non-IBC young'); and 3) non-IBC patients over age 45 yr at diagnosis. For each subset population, we evaluated clinicopathologic characteristics, sites of metastasis, survival outcomes, and cfDNA 'tumor fraction' – the fraction of DNA in circulation derived from tumor. Those patients with adequate cfDNA tumor content for high confidence copy number calls (n=101) were included in an analysis of copy number alterations.

Results: Among 164 patients with metastatic TNBC, 13.4% (22/164) had IBC, 37.8% (62/164) were non-IBC young, and 48.8% (80/164) were non-IBC and over 45 yr. Race and primary receptor status were similar. IBC patients were diagnosed at a higher stage (Chi-square p=0.0009) while non-IBC young patients were significantly more likely to harbor a BRCA mutation (Chi-square p=0.03). Analysis of metastatic sites revealed that IBC patients had significantly greater frequency of ipsilateral and contralateral breast chest wall recurrences (p=0.04 and p=0.046, respectively) while non-IBC young patients had the most frequent lung metastases (p=0.002). There were no significant differences in frequency of bone, brain, or liver metastases. cfDNA analyses showed that cfDNA 'tumor fraction' was highest in non-IBC young patients (ANOVA p=0.03 for maximum tumor fraction). Median overall survival from metastatic diagnosis was 22.9 months. IBC and non-IBC young patients had a worse prognosis relative to non-IBC patients over 45 yr (hazard ratio IBC=1.97, 95% CI 1.09-3.57; HR non-IBC young=1.60 95% CI 1.07-2.41; log-rank p=0.023). By subgroup, median overall survival from metastatic diagnosis for IBC was 15.2 months, non-IBC young 21.2 months, and non-IBC over 45 yr 31.2 months. Analyses of genome-wide copy number alterations from cell-free DNA will be presented.

Conclusions: Among metastatic TNBCs, IBC patients and non-IBC young patients have a significantly worse overall survival compared with non-IBC patients over 45 yr of age. Young patients have more frequent lung metastases and higher 'tumor fraction' of cfDNA. Confirmation of the reported findings is limited due to cohort size and may reflect referral bias.

Citation Format: Singh J, Asad S, Nock W, Zhang Y, Adams E, Damicis A, Parsons HA, Adalsteinsson VA, Winer EP, Lin NU, Partridge AH, Overmoyer B, Stover DG. Aggressive subgroups of metastatic triple-negative breast cancer: Inflammatory breast cancer and young patients in the Dana-Farber cell-free DNA cohort [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 P4-01-17.

Wolbachia-induced transcription factor GATA4 suppresses ovary-specific genes blastoderm-specific protein 25D and imaginal disc growth factor

The endosymbiotic bacterium Wolbachia infects a wide array of insect hosts and has been implicated in a range of biological modifications as a consequence of its infection. Previously, it was shown that the transcription factor GATA4 was significantly induced in Wolbachia wMelPop-CLA strain infected Aedes aegypti whole mosquitoes and cells. Here, we provide evidence that this induction also occurs in mosquito ovaries where the ovary-specific genes blastoderm-specific protein 25D (Bsg25D) and imaginal disc growth factor (Disc) are suppressed by Wolbachia. We further demonstrate that transcriptional depletion of GATA4 results in upregulation of both genes and conversely its overexpression leads to downregulation of the genes, suggesting that Wolbachia-induced GATA4 plays a suppressive regulatory role with regards to Bsg25D and Disc expression in mosquito ovaries. When the Disc gene was silenced in mosquitoes, we did not observe any difference in the number of mature ovarian follicles developed between treatment groups. However, we did find a significant delay in the hatching of eggs that had been laid by Disc knockdown mosquitoes.

Clival Defect with Primary CSF Rhinorrhea: A Very Rare Presentation with Challenging Management

BACKGROUND

Primary spontaneous cerebrospinal fluid (CSF) rhinorrhea due to clival defect is an extremely rare presentation, and only 6 cases have been reported in the literature so far¹⁷.

CASE DESCRIPTION

We present a unique case of a 64-year-old woman who presented with a 2-year history of ongoing CSF rhinorrhea. She had similar episode at the age of 40 years and suffered from meningitis. She underwent magnetic resonance imaging, computed tomography cisternogram, as well as computed tomography of the brain, which showed clival defect with CSF leak into the sphenoid sinus. She underwent transsphenoidal repair of the clival defect with concurrent lumbar drain insertion for CSF drainage. She returned a few months later with recurrent CSF rhinorrhea and meningitis. She was administered broad-spectrum antibiotics and underwent septal reconstruction of clival defect.

CONCLUSIONS

Timely endoscopic transnasal, transsphenoidal repair of CSF leaks is the gold standard practice and could prevent devastating complications including repeated episodes of meningitis.

Diabetes mellitus and the risk of cancer

Although diabetes has been known to increase the risk of cancer for over a century, it was not until recently when this area gained momentum and generated a lot of interest. That is in- part because of the rising global diabetes epidemic and the wide spread use of insulin analogues, metformin and other anti-diabetic agents, providing hypothesis generating data on the cancer risk in the diabetic population. Type 2 diabetes is associated with increased risk of breast, colon, pancreatic and other types of cancer, while type 1 diabetes is associated with increase in stomach, pancreatic, endometrial and cervical cancer. Mechanisms postulated for increased cancer risk in diabetes include hyperglycemia, hyperinsulinemia with stimulation of IGF-1 axis, obesity that serves as a common soil hypothesis for both cancer and diabetes as well as other factors such as increased cytokine production. More recently some antidiabetic agents have been thought to increase cancer risk such as insulin glargine, while metformin appears to lower cancer risk. In this review, we present the evidence for the link between diabetes and cancer highlighting the general mechanisms proposed for such a link as well as specific hypotheses for individual cancer. We will also discuss the role of insulin, metformin and other antidiabetic agents in cancer risk.

Engineering broad-spectrum resistance against RNA viruses in potato

RNA silencing technology has become the tool of choice for inducing resistance against viruses in plants. A significant discovery of this technology is that double-stranded RNA (dsRNA), which is diced into small interfering RNAs (siRNAs), is a potent trigger for RNA silencing. By exploiting this phenomenon in transgenic plants, it is possible to confer high level of virus resistance by specific targeting of cognate viral RNA. In order to maximize the efficiency and versatility of the vector-based siRNA approach, we have constructed a chimeric expression vector containing three partial gene sequences derived from the ORF2 gene of Potato virus X, Helper Component Protease gene of Potato virus Y and Coat protein gene of Potato leaf roll virus. Solanum tuberosum cv. Desiree and Kuroda were transformed with this chimeric gene cassette via Agrobacterium tumefaciens-mediated transformation and transgenic status was confirmed by PCR, Southern and double antibody sandwich ELISA detection. Due to simultaneous RNA silencing, as demonstrated by accumulation of specific siRNAs, the expression of partial triple-gene sequence cassette depicted 20% of the transgenic plants are immune against all three viruses. Thus, expression of a single transgene construct can effectively confer resistance to multiple viruses in transgenic plants.

No evidence of association of the PDCD1 gene with Type 1 diabetes

AIMS

To test the association between the immunoreceptor PD-1 (PDCD1) gene and Type 1 diabetes mellitus (T1DM). This gene has been reported to be associated with other autoimmune diseases such as systemic lupus erythematosus (SLE) as well as T1DM.

METHODS

Genotyping of single nucleotide polymorphisms (SNPs) in the PDCD1 gene was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), pyrosequencing and TaqMan in two separate cohorts of Swedish patients and control subjects: a family study consisting of 184 multiplex and eight simplex families and a case-control study consisting of 586 patients and 836 control subjects. Three SNPs were genotyped: PD-1 7146, PD-1 7785 and PD-1 8738.

RESULTS

We did not detect any association or linkage between SNPs in PDCD1 and T1DM. We further performed a meta-analysis for association of PD-1 7146, PD-1 7785 and PD-1 8738 to T1DM. We detected heterogeneity in association with weak evidence for overall association.

CONCLUSIONS

We conclude that PDCD1 is unlikely to be a major susceptibility gene for T1DM.

Bioemulsifier production by a halothermophilic Bacillus strain with potential applications in microbially enhanced oil recovery

A halothermotolerant Gram-positive spore-forming bacterium was isolated from petroleum reservoirs in Iran and identified as Bacillus licheniformis sp. strain ACO1 by phenotypic characterization and 16S rRNA analysis. It showed a high capacity for bioemulsifier production and grew up to 60 degrees C with NaCl at 180 g l(-1). The optimum NaCl concentration, pH and temperature for bioemulsifier production were 4% (w/v), 8.0, and 45 degrees C, respectively. Although ACO1 did not utilize hydrocarbons, it had a high emulsifying activity (E (24) = 65 +/- 5%) on different hydrophobic substrates. Emulsification was optimal while growing on yeast extract as the sole carbon source and NaNO(3) as the nitrogen source. The efficiency of the residual oil recovery increased by 22% after in situ growth of B. licheniformis ACO1 in a sand-pack model saturated with liquid paraffin.

Decolorization of textile azo dyes by newly isolated halophilic and halotolerant bacteria

Studies were carried out on the decolorization of textile azo dyes by newly isolated halophilic and halotolerant bacteria. Among the 27 strains of halophilic and halotolerant bacteria isolated from effluents of textile industries, three showed remarkable ability in decolorizing the widely utilized azo dyes. Phenotypic characterization and phylogenetic analysis based on 16S rDNA sequence comparisons indicate that these strains belonged to the genus Halomonas. The three strains were able to decolorize azo dyes in a wide range of NaCl concentration (up to 20%w/v), temperature (25-40 degrees C), and pH (5-11) after 4 days of incubation in static culture. They could decolorize the mixture of dyes as well as pure dyes. These strains also readily grew in and decolorized the high concentrations of dye (5000 ppm) and could tolerate up to 10,000 ppm of the dye. UV-Vis analyses before and after decolorization and the colorless bacterial biomass after decolorization suggested that decolorization was due to biodegradation, rather than inactive surface adsorption. Analytical studies based on HPLC showed that the principal decolorization was reduction of the azo bond, followed by cleavage of the reduced bond.

Transgenic tobacco expressing geminiviral RNAs are resistant to the serious viral pathogen causing cotton leaf curl disease

Cotton, the major cash crop in Pakistan, suffers 30% losses to cotton leaf curl disease, caused by the geminivirus, cotton leaf curl virus DNA A, plus a satellite component, DNA beta responsible for symptom development with plants failing to produce cotton bolls. We constructed transgenic tobacco expressing sense and antisense RNAs representing: [i] the 5' half of the viral DNA replication gene, AC1, [ii] the 3' half of AC1, [iii] two overlapping genes, AC2, a transcription activator, and AC3, a replication enhancer. In contrast to controls, 25% of 72 transgenic tobacco lines tested showed heritable resistance [T(1) - T(3) generations]: symptom-free and no replication of DNA A or DNA beta even after 120 days of continuous exposure to viruliferous whiteflies. As geminiviral and transgene RNAs are not detected in resistant lines following infection, and selected uninfected resistant tobacco sense lines reveal double-stranded and small interfering RNAs, the most likely mechanism is via post-transcriptional gene silencing.

Inhibition of human immunodeficiency virus type 1 multiplication by antisense and sense RNA expression

Human immunodeficiency virus type 1 (HIV-1) primarily infects CD4+ lymphocytes and macrophages and causes AIDS in humans. Retroviral vectors allowing neomycin phosphotransferase (npt) gene expression were engineered to express 5' sequences of HIV-1 RNA in the antisense or sense orientation and used to transform the human CD4+ lymphocyte-derived MT4 cell line. Cells expressing antisense or sense RNA to the HIV-1 tat mRNA leader sequence, as part of the 3' untranslated region of the npt mRNA, remained sensitive to HIV-1 infection. In contrast, resistance to HIV-1 infection was observed in cells expressing antisense RNA to the HIV-1 primer-binding site or to the region 5' to the primer-binding site as part of the 3' region of the npt mRNA. Cells expressing the tat mRNA leader sequence in the sense orientation as a precise replacement of the 5' untranslated region of npt mRNA were also resistant to HIV-1. These results indicate that sense and antisense approaches can be used to interfere with HIV-1 multiplication.

Resistance to human immunodeficiency virus type 1 (HIV-1) infection in human CD4+ lymphocyte-derived cell lines conferred by using retroviral vectors expressing an HIV-1 RNA-specific ribozyme

Toward gene therapy for the treatment of human immunodeficiency virus type 1 (HIV-1) infections in AIDS, Moloney murine leukemia virus-derived retroviral vectors were engineered to allow constitutive and tat-inducible expression of an HIV-1 5' leader sequence-specific ribozyme (Rz1). These vectors were used to infect the human CD4+ lymphocyte-derived MT4 cell line. The stable MT4 transformants expressing an HIV-1 RNA-specific ribozyme, under the control of the herpes simplex virus thymidine kinase (tk) promoter, were found to be somewhat resistant to HIV-1 infection as virus production was delayed. In cells allowing ribozyme expression under control of the simian virus 40 or cytomegalovirus promoter, the rate of HIV-1 multiplication was slightly decreased, and virus production was delayed by about 14 days. The highest level of resistance to HIV-1 infection was observed in MT4 cells transformed with a vector containing a fusion tk-TAR (trans activation-responsive) promoter to allow ribozyme expression in a constitutive and tat-inducible manner; no HIV-1 production was observed 22 days after infection of these cells. These results indicate that retroviral vectors expressing HIV-1 RNA-specific ribozymes can be used to confer resistance to HIV-1 infection.

Comparative inhibitory and bactericidal activities of FCE 22101 against gram-positive cocci and anaerobes in vitro

The inhibitory activity of penem FCE 22101 was compared with those of imipenem and other relevant antibiotics against over 500 clinical isolates of Gram-positive cocci and anaerobes. The relative bactericidal activities of FCE 22101 and imipenem were compared by a killing curve method. FCE 22101 showed good inhibitory activity against most aerobic Gram-positive cocci although generally less than imipenem. A substantial number of Staphylococcus aureus isolates (43%) were highly susceptible to imipenem (MIC less than 0.0015 mg/l); the mode MIC for FCE 22101 was 0.06 mg/l. Methicillin-resistant Staph. aureus (MRSA) were often slightly more susceptible to FCE 22101 than to imipenem. Streptococci were more susceptible to imipenem than to FCE 22101; mode MICs for group A streptococci were 0.003 and 0.03 mg/l and for enterococci 1 and 4 mg/l, respectively. The anaerobic organisms tested were equally susceptible to both FCE 22101 and imipenem. Imipenem and FCE 22101 showed similar bactericidal activity at a concentration equivalent to 4 x MIC. Fully susceptible staphylococci were killed rapidly by both compounds, whereas less susceptible isolates, especially MRSA, were killed slowly. Streptococci, other than Str. pneumoniae, were also killed relatively slowly. Bacteroides fragilis group organisms were rapidly killed by both FCE 22101 and imipenem.

Potential target sites for antiviral inhibitors of human immunodeficiency virus (HIV)

The rapid identification of anti-HIV compounds in the laboratory following the isolation of the causative virus in 1983 and their subsequent use in the clinic was not unexpected. Three decades of previous work had established a scientific basis for the evaluation of antiviral compounds. However, no antiviral yet discovered can cause total blockade of a virus replicating in a cell. The combination of properties of HIV including latency, antigenic and biochemical variation is unusual and the virus represents a daunting challenge for chemotherapy. But at least 90 antiviral compounds have been discovered, many inhibiting the virus reverse transcriptase. Other targets for inhibition are possible including viral regulatory gene products, viral protease and endonuclease enzymes but compounds for initial study will have to be found by random searching. X-ray crystallography of HIV proteins will shortly be possible, enabling the commencement of a more molecular specific search for inhibitors. Meanwhile, advantage can be taken of comparative nucleotide sequences of the HIV-1 and -2 genomes to test short oligonucleotides as potential inhibitors of mRNA transcription. The pol gene also has a zinc finger amino acid sequence suggesting that chelation chemotherapy may have a potential role. In the absence of HIV vaccines, and associated theoretical problems in their development, antiviral chemotherapy is expected to occupy a central role in combating the AIDS epidemic.

Effect of uremic sera on parathyroid hormone (PTH) mediated release of calcium from normal rat embryonal bone maintained in tissue culture

1. 45Ca released from embryonal fetal rat bone into a tissue culture system containing uremic serum was lower than 45Ca measured in culture media containing normal sera. 2. With stimulation of bone calcium mobilization by the addition of PTH, 1,25(OH)2D3, 24,25(OH)2D3 and 25 (OH)2D3, the 45Ca released into media containing uremic serum was significantly lower than measured in cultures containing normal serum. 3. Addition of PTH in combination with 24,25(OH)2D3 or with 24,25(OH)2D3 and 1,25(OH)2D3 to bone cultures containing uremic serum increased the 45Ca released into the media when compared to cultures containing uremic serum and PTH.