Linking Chromosomal Silencing With Xist Expression From Autosomal Integrated Transgenes

Xist is the master regulator of X-Chromosome Inactivation (XCI), the mammalian dosage compensation mechanism that silences one of the two X chromosomes in a female cell. XCI is established during early embryonic development. Xist transgene (Tg) integrated into an autosome can induce transcriptional silencing of flanking genes; however, the effect and mechanism of Xist RNA on autosomal sequence silencing remain elusive. In this study, we investigate an autosomal integration of Xist Tg that is compatible with mouse viability but causes male sterility in homozygous transgenic mice. We observed ectopic Xist expression in the transgenic male cells along with a transcriptional reduction of genes clustered in four segments on the mouse chromosome 1 (Chr 1). RNA/DNA Fluorescent in situ Hybridization (FISH) and chromosome painting confirmed that Xist Tg is associated with chromosome 1. To determine the spreading mechanism of autosomal silencing induced by Xist Tg on Chr 1, we analyzed the positions of the transcriptionally repressed chromosomal sequences relative to the Xist Tg location inside the cell nucleus. Our results show that the transcriptionally repressed chromosomal segments are closely proximal to Xist Tg in the three-dimensional nucleus space. Our findings therefore support a model that Xist directs and maintains long-range transcriptional silencing facilitated by the three-dimensional chromosome organization.

Functional Conservation of LncRNA JPX Despite Sequence and Structural Divergence

Long noncoding RNAs (lncRNAs) have been identified in all eukaryotes and are most abundant in the human genome. However, the functional importance and mechanisms of action for human lncRNAs are largely unknown. Using comparative sequence, structural, and functional analyses, we characterize the evolution and molecular function of human lncRNA JPX. We find that human JPX and its mouse homolog, lncRNA Jpx, have deep divergence in their nucleotide sequences and RNA secondary structures. Despite such differences, both lncRNAs demonstrate robust binding to CTCF, a protein that is central to Jpx's role in X chromosome inactivation. In addition, our functional rescue experiment using Jpx-deletion mutant cells shows that human JPX can functionally complement the loss of Jpx in mouse embryonic stem cells. Our findings support a model for functional conservation of lncRNAs independent from sequence and structural divergence. This study provides mechanistic insight into the evolution of lncRNA function.

Abstract 1717: Orthogonal identification of circulating tumor cells (CTCs) using single cell low pass whole-genome sequencing (WGS) and copy-number alteration (CNA) analysis

Introduction: Presence of circulating tumor cells has prognostic value in multiple malignancies, and molecular analysis of CTCs is currently ongoing in numerous clinical trials. Most CTC enrichment methods rely on standard epithelial and leukocyte markers (CK+CD45-), so recovered cells are assumed to be of epithelial origin but never shown to be bona fide tumor cells. Conversely, atypical cells lacking the characteristic marker profile may not be analyzed, even though they may represent important tumor subpopulations. Here we evaluate a rapid, non-exhaustive, and cost-effective first-pass genomic analysis of individual candidate CTCs. This approach allows efficient upfront CNA-based confirmation that a given cell is of tumor origin, while leaving abundant DNA for deeper subsequent analysis in cells of interest.

Methods: Whole peripheral blood of metastatic prostate cancer patients was enriched for CTCs using the CellSearch® system (Janssen Diagnostics) under an IRB-approved protocol, and 5 samples with >5 CTCs were selected for further study. Next, the DEPArray™ v2 system (Menarini Silicon Biosystems) was used to identify and isolate single CTCs (CK+CD45-DAPI+) and paired white blood cells (WBCs; CK-CD45+DAPI+) from the enriched samples. In addition, cells negative for both cytokeratin and CD45 but with characteristic malignant morphology (large with high nuclear-cytoplasmic ratio) were isolated. Recovered single cells were whole-genome amplified with Ampli1™ WGA and quality controlled by Ampli1 QC. Ampli1 LowPass kit was then used to prepare NGS libraries for absolute CNA profiling by low-pass WGS.

Results: Thirty-three single CTCs (CK+CD45-DAPI+) and 30 WBCs (CK-CD45+DAPI+), as well as 47 putative CTCs with non-conventional phenotype (CK-CD45-DAPI+) were isolated. Single-cell WGA products with high Genome-Integrity Index (QC score ≥3) were prioritized for CNA analysis. Ampli1 LowPass data demonstrated copy number gains/losses confirming tumor origin of the CK+ cells, while WBCs showed a normal profile. In addition, a portion of the cells having non-conventional phenotype also demonstrated copy number alterations consistent with tumor origin.

Discussion: We demonstrate a WGA and low-pass WGS approach on single CTCs sorted from enriched peripheral blood, which offers a dual benefit: i) it allows rapid, non-exhaustive upfront identification of bona fide tumor cells for further study, and ii) it reveals genetic similarities and diversities (vis a vis copy number alteration) across CTCs of classical as well as non-conventional phenotypes, which may better represent clonal diversity. In a clinical setting, this molecular approach may be more effective for reliably identifying and characterizing heterogeneous CTCs, yielding profiles that more accurately reflect disease evolution and inform treatment strategies.

Citation Format: Gareth Morrison, Valeria Sero, Yucheng Xu, Jacek Pinski, Sue Ingles, David Quinn, Claudio Forcato, Genny Buson, Chiu-Ho Webb, Kyle Horvath, Aditi Khurana, Gianni Medoro, Suman Verma, Matthew Moore, Philip Cotter, Nicolò Manaresi, Farideh Bischoff, Amir Goldkorn. Orthogonal identification of circulating tumor cells (CTCs) using single cell low pass whole-genome sequencing (WGS) and copy-number alteration (CNA) analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1717. doi:10.1158/1538-7445.AM2017-1717

A self-enhanced transport mechanism through long noncoding RNAs for X chromosome inactivation

X-chromosome inactivation (XCI) is the mammalian dosage compensation strategy for balancing sex chromosome content between females and males. While works exist on initiation of symmetric breaking, the underlying allelic choice mechanisms and dynamic regulation responsible for the asymmetric fate determination of XCI remain elusive. Here we combine mathematical modeling and experimental data to examine the mechanism of XCI fate decision by analyzing the signaling regulatory circuit associated with long noncoding RNAs (lncRNAs) involved in XCI. We describe three plausible gene network models that incorporate features of lncRNAs in their localized actions and rapid transcriptional turnovers. In particular, we show experimentally that Jpx (a lncRNA) is transcribed biallelically, escapes XCI, and is asymmetrically dispersed between two X's. Subjecting Jpx to our test of model predictions against previous experimental observations, we identify that a self-enhanced transport feedback mechanism is critical to XCI fate decision. In addition, the analysis indicates that an ultrasensitive response of Jpx signal on CTCF is important in this mechanism. Overall, our combined modeling and experimental data suggest that the self-enhanced transport regulation based on allele-specific nature of lncRNAs and their temporal dynamics provides a robust and novel mechanism for bi-directional fate decisions in critical developmental processes.

The impact of a PCR assay for candidemia on antifungal drug prescribing in critical care: an interrupted time series pilot study

SUMMARY OBJECTIVE

To evaluate the feasibility of conducting a definitive study to assess the impact of introducing a rapid PCR-based test for candidemia on antifungal drug prescribing.

METHOD

Prospective, single centre, interrupted time series study consisting of three periods of six months' duration. The assay was available during the second period, during which the PCR assay was available for routine use by physicians Monday-Friday with guaranteed 24-h turnaround time. For each period total antifungal drug use, expressed as treatment-days, was recorded and an adjustment was made to exclude estimated use for proven candidemia. Also, during the intervention period, antifungal prescribing decisions for up to 72 h after each PCR result became available were recorded as either concordant or discordant with that result.

RESULTS

While overall antifungal use remained relatively stable throughout, after adjustment for candidemia, there was a 38% reduction in use following introduction of the PCR test; however, this was nonsignificant at the 95% level. During the intervention period overall concordance between the PCR result and prescribing decisions was 84%.

CONCLUSIONS

The PCR assay for candidemia was requested, prescribing decisions were generally concordant with the results produced and there was an apparent decrease in antifungal prescription, although this was sustained even after withdrawal of the intervention; these findings should be more thoroughly evaluated in a larger trial.

Rapid differentiation between fluconazole-sensitive and -resistant species of Candida directly from positive blood-culture bottles by real-time PCR

In view of both the delay in obtaining identification by conventional methods following blood-culture positivity in patients with candidaemia and the close relationship between species and fluconazole (FLC) susceptibility, early speciation of positive blood cultures has the potential to influence therapeutic decisions. The aim was to develop a rapid test to differentiate FLC-resistant from FLC-sensitive Candida species. Three TaqMan-based real-time PCR assays were developed to identify up to six Candida species directly from BacT/Alert blood-culture bottles that showed yeast cells on Gram staining at the time of initial positivity. Target sequences in the rRNA gene complex were amplified, using a consensus two-step PCR protocol, to identify Candida albicans, Candida parapsilosis, Candida tropicalis, Candida dubliniensis, Candida glabrata and Candida krusei; these are the most commonly encountered Candida species in blood cultures. The first four of these (the characteristically FLC-sensitive group) were identified in a single reaction tube using one fluorescent TaqMan probe targeting 18S rRNA sequences conserved in the four species. The FLC-resistant species C. krusei and C. glabrata were detected in two further reactions, each with species-specific probes. This method was validated with clinical specimens (blood cultures) positive for yeast (n=33 sets) and the results were 100 % concordant with those of phenotypic identification carried out concomitantly. The reported assay significantly reduces the time required to identify the presence of C. glabrata and C. krusei in comparison with a conventional phenotypic method, from ∼72 to <3 h, and consequently allows optimization of the antifungal regimen at an earlier stage.

Trends in candidemia and antifungal susceptibility in a university hospital in Northern Ireland 2001-2006

OBJECTIVES

To describe the species distribution and antifungal susceptibility trends for documented episodes of candidemia at the Royal Hospitals, Belfast, 2001-2006.

METHODS

Laboratory-based retrospective observational study of all episodes of candidemia.

RESULTS

There were 151 episodes of candidemia. The species recovered were: 96 C. albicans; 26 C. glabrata; 18 C. parapsilosis; five C. tropicalis; four C. guilliermondii; one C. famata and one C. dubliniensis. We separated the data into two periods 2001-2003 and 2004-2006; contrary to the findings of other investigators, there was a notable trends toward increasing frequency of C. albicans and decreasing frequency of non-albicans species over time. Although the proportion of C. albicans, C. parapsilosis and C. tropicalis isolates susceptible to fluconazole was unchanged over time, a trend of decreased susceptibility of C. glabrata to fluconazole was noted over the six-year period. Overall, 73% and 7.7% of C. glabrata isolates had susceptible-dose-dependent and resistant phenotypes, respectively. The percentage of C. glabrata isolates susceptible to fluconazole (MIC <8 microg/ml) decreased from 36% in 2001-2003 to 0% in 2004-2006. Flucytosine resistance was detected in only 4 (2.7%) isolates. None of the isolates had an amphotericin B MIC <1 microg/ml.

CONCLUSION

A shift towards increasing dominance of C. albicans contrasts both with reports from other countries and previous data from Northern Ireland. Upwards fluconazole MIC drift among C. glabrata has important implications for empirical therapeutic decisions.

A prospective clinical study of Epstein-Barr virus and host interactions during acute infectious mononucleosis

BACKGROUND

Characterizing virus-host interactions during self-limited infectious mononucleosis could explain how Epstein-Barr virus (EBV) replication is normally controlled and provide insight into why certain immunocompromised patients fail to contain it.

METHODS

University students had an average of 7 clinical and virologic evaluations during acute infectious mononucleosis. EBV was quantified in 697 samples of oral wash fluid, whole blood, peripheral blood mononuclear cells (PBMCs), and plasma by a real-time (TaqMan) polymerase chain reaction (qEBV) assay developed in our laboratory.

RESULTS

Twenty of 25 subjects had serologically confirmed primary EBV infection. EBV was cleared from whole blood by a first-order process with a median half-life of 3 days, and its quantity was associated with severity of illness (r2=0.82). Oral shedding persisted at a median of >or=1x104 copies/mL for 32 weeks and was unrelated to severity of illness. Subjects with nonprimary EBV infection shed virus intermittently, and median quantities for all samples became undetectable within 4 weeks.

CONCLUSIONS

Using a novel qEBV assay, we demonstrated that young adults with primary EBV infection rapidly cleared virus from blood but not from the oropharynx. High oral concentrations of EBV in asymptomatic persons who have resumed normal activities support the concept that infectious mononucleosis is most likely acquired by kissing.

Tricuspid valvar endocarditis caused by penicillin resistant pneumococcus

A 6-year-old boy presented with endocarditis of the tricuspid valve caused by penicillin resistant pneumococcus. He had no history of congenital cardiac disease. The likely portal of entry for the organism was the middle ear.

Implications of endotracheal tube biofilm for ventilator-associated pneumonia

OBJECTIVE

To determine the relationship between, and antibiotic resistance of, endotracheal tube (ET) biofilm and pulmonary pathogens in ventilator-associated pneumonia (VAP).

SETTING

General intensive care units in two university teaching hospitals.

DESIGN

The microbiology of ET biofilm and tracheal samples from patients with and without VAP were compared. For individual patients, matching pairs of pathogens were confirmed as identical and characterised for antibiotic susceptibility.

PATIENTS

40 intensive care unit patients - 20 with VAP, 20 without VAP as control. The duration of intubation (median and range) was 6.5 days (3-17) and 5 days (2-10), respectively.

MEASUREMENTS AND RESULTS

Samples of tracheal secretions were taken during ventilation for bacteriological culture. Following extubation, ETs were examined for the presence of biofilm. Isolates of high pathogenic potential included Staphylococcus aureus, enterococci, Enterobacteriaceae, pseudomonads and Candida spp. Where the same microorganism was found on tracheal and ET samples by phenotyping, these were confirmed as identical by genotyping and characterised for antibiotic susceptibility in both the free floating and biofilm forms. Seventy per cent of patients with VAP had identical pathogens isolated from both ET biofilm and tracheal secretions. No pairing of pathogens was observed in control patients (p < 0.005). Susceptibility data for these pairs show that the ET acts as a reservoir for infecting microorganisms which exhibit significantly greater antibiotic resistance than their tracheal counterparts.

CONCLUSION

This investigation provides further evidence for the role of ET biofilm in VAP. The difficulty in eradicating an established microbial biofilm using antibiotics implies that increased attention must be directed towards modification of the ET to prevent or substantially reduce biofilm formation.

Closed tracheal suctioning systems and infection control in the intensive care unit

Closed tracheal suction catheters offer a number of microbiological advantages over the conventional single-use suction catheters. Intensive care staff, however, have experienced difficulties such as pooling of the catheter irrigation saline within the connectors, and hand contamination from condensate which escapes via the irrigation port. Using a descriptive survey design we quantified how frequently these problems occurred. Over an eight-week period, staff completed 923 survey forms. Hand contamination from condensate was reported in 61% of responses. Rinsing the catheter after use was ineffective in 39% of responses, and 70% reported pooling of the saline in the swivel and ventilator connectors. Forty-five percent of responses reported ineffective secretion removal. The infection implications for clinical practice are discussed.

Contamination of multi-use closed tracheal suction catheters: an in-vitro study

The use of closed multi-use tracheal suction systems in ventilated patients is increasingly popular as it offers a number of potential physiological and microbiological advantages. As the use of these systems has been associated with an increased prevalence of tracheal colonization, effective self-cleaning mechanisms employed in these catheters are necessary. Using an in-vitro model we assessed the degree of catheter colonization in two multi-use catheter systems; Stericath and Trach-Care. Fifty of each catheter type were tested for colonization with five challenge organisms: Staphylococcus aureus (NCTC 6571); Pseudomonas aeruginosa (NCTC 10662); Haemophilus influenzae type b; S. epidermidis (slime producer); and S. epidermidis (slime non-producer). All five challenge strains had colonized both catheter types after 24 h and all 100 catheter tips were colonized. The extent and density of colonization was variable and interspecies variation in the pattern of catheter colonization was observed. The mean colonized lengths of Stericath catheters was 10.9 +/- 1.4 cm and of Trach-Care 2.7 +/- 1.3 cm (P < 0.0001).

Investigation of a nosocomial outbreak of Pseudomonas aeruginosa pneumonia in an intensive care unit by random amplification of polymorphic DNA assay

From July to September 1993 in the intensive care unit of the Royal Victoria Hospital there were 10 cases of pneumonia associated with sputum culture of Pseudomonas aeruginosa. The isolates had an identical biotype and pyocine typing profile. The same strain of P. aeruginosa was recovered from the sink plug-hole in two rooms, and the tap handles and ventilator tubing in a third room. All strains were retrospectively typed by the random amplification of polymorphic DNA (RAPD) method using a 26-mer oligonucleotide primer, and were identical in profile. Recommendations to medical and nursing staff included secretion isolation precautions, terminal disinfection after patient discharge, use of disposable vinyl gloves by hospital staff for all body substance contacts, thorough handwashing with 4% chlorhexidine gluconate before and after dealing with all patient contacts, and prompt, appropriate antibiotic treatment for P. aeruginosa pneumonia. RAPD is a simple and effective method to determine the relatedness of P. aeruginosa isolates, and typing results are available within a single working day; thus dramatically increasing its clinical relevance over existing molecular methods.

Market penetration of new drugs in one United Kingdom region: implications for general practitioners and administrators

OBJECTIVE

To determine the use of new drugs in one United Kingdom region.

DESIGN

Examination of data on prescribing of angiotensin converting enzyme inhibitors, new broad spectrum antibiotics, and H2 receptor antagonists. Calculation of number of defined daily doses prescribed each month.

SETTING

All general practices in Northern Ireland.

MAIN OUTCOME MEASURES

Drug use index and market share of each drug.

RESULTS

During 1988-91 prescribing of angiotensin converting enzyme inhibitors increased by 126%, of H2 receptor antagonists by 46%, and of new antibiotics by 207%. The first drug on the market usually retained the largest market share. Use of oral antibiotics increased threefold irrespective of the reporting policy of the general practitioners' local laboratory.

CONCLUSIONS

The increase in prescribing of these drugs seems to be greater than can be accounted for by an increase in patients with specific indications for these drugs. This suggests that the profession has not instituted effective checks to ensure that the legitimate promotion of new products does not lead to inappropriate and wasteful use.

Selective decontamination of the digestive tract (SDD) does not prevent the formation of microbial biofilms on endotracheal tubes

The purpose of selective decontamination of the digestive tract (SDD) is to eradicate potentially disease-producing micro-organisms from the oropharynx and gastro-intestinal tract of intensive care unit (ICU) patients, thereby reducing the incidence of nosocomial sepsis, particularly pneumonia. Microbial biofilms form on endotracheal (ET) tubes even when SDD is being administered and may represent a persistent focus for infection. The aim of this investigation was to determine the susceptibilities of organisms adherent to ET tubes to SDD antibiotics (amphotericin B, tobramycin and polymyxin) and to measure the concentrations of these agents in the tracheal aspirates of 11 patients who were being mechanically ventilated. Following extubation, a section was cut from the tip of each ET tube and any adherent microorganisms subsequently isolated were identified and their MICs determined. Samples of tracheal aspirate were obtained three hours after administration of the SDD regimen and the concentrations of the constituent antimicrobials were measured. Enterobacteriaceae were not recovered from any of the tubes but six strains of Staphylococcus aureus, three Pseudomonas spp., three enterococci and four yeasts were isolated. Wide variations in the concentrations of all antibiotics were observed and in many cases they were below the MICs for the organisms isolated. In particular, tobramycin concentrations were uniformly less than the median MIC for the S. aureus isolates and this may account for the predominance of Gram-positive bacteria adherent to the ET tubes. Microbial biofilms attached to these tubes may have a role in the pathogenesis of nosocomial pneumonia in ICU patients.

Helping the helpers: the development of a critical incident stress management team through university/community cooperation

Prehospital emergency services personnel often are exposed to high levels of occupational stress. Besides chronic stress, they can be involved in critical incidents, which cause a well-recognized set of overwhelming emotional reactions. If these reactions are not addressed promptly, emergency responders and their families can suffer further emotional trauma, and this can impair the ability of responders to care for patients in the field. A critical incident stress management team has been established through cooperation between the Charleston Division of the West Virginia University Health Sciences Center and emergency personnel in Charleston, as well as the rural countries in southern West Virginia. This team provides preincident education and postincident interventions for firefighters, police, emergency medical services, and on occasion, hospital emergency department personnel. This team can serve as a model for other such teams to organize to deal with this growing problem in the health care delivery field.

Five cases of Alcaligenes pseudobacteraemia

A cluster of five cases of pseudobacteraemia due to the organism Alcaligenes denitrificans occurred in three hospital medical wards over a four week period. The same organism was isolated from four of twelve commercially prepared bottles for erythrocyte sedimentation tests. The most likely explanation for the outbreak is that the ESR bottles were filled prior to inoculation of blood culture bottles. The outbreak was brought to an end by advising on correct procedure.

Antibiotic resistance associated with selective decontamination of the digestive tract

Selective decontamination of the digestive tract (SDD) appears to reduce infection, particularly pneumonia, in intensive care, and some patients benefit markedly. Gram-positive overgrowth and antibiotic resistance in both Gram-positive and Gram-negative organisms has been recorded. However, the clinical and epidemiological significance of these observations is still debated. Future studies will need to be of sufficient size and duration to provide good quality data on which the safety and efficacy of SDD can be properly judged.

Critical incident stress in prehospital emergency care

In addition to the routine pressures associated with their demanding roles, prehospital emergency responders can suffer severe stress as a result of exposure to a critical incident. Such an event overwhelms the individual's ability to emotionally adjust, and can lead to symptoms which cause suffering in emergency personnel, their families and their patients. A Critical Incident Stress Management (CISM) Team has been established in southern West Virginia to address this occupational hazard. This group was formed as a cooperative arrangement between the Charleston Division of the West Virginia University Health Sciences Center and emergency personnel in the Greater Kanawaha Valley. This article offers an explanation of the team's functioning and specific information regarding its activation.

Epidemiology of Pseudomonas aeruginosa in an intensive care unit using selective decontamination of the digestive tract

Selective decontamination of the digestive tract (SDD) aims to reduce the rate of nosocomial infections in critical care patients. Pseudomonas spp. are common nosocomial pathogens and in this study isolates collected from patients and the environment during an SDD trial were examined. The study enrolled 161 SDD cases and 170 controls. Pseudomonads were isolated from 27% of SDD patients and 30% of controls. SDD partially suppressed colonization in the 'gastro-respiratory' mucosae but not in the rectum. A total of 108 isolates of pseudomonads were recovered from the environment. Resistance in rectal isolates was minimal but isolates from 'gastro-respiratory' sites showed increasing aminoglycoside resistance. Eighty-six per cent of aminoglycoside-resistant isolates from both patient groups and environment were pyocine type 1x. Episodes of infection were reduced in the SDD patients (6) compared with the controls (16), aminoglycoside-resistant strains being associated with zero episodes in SDD patients but with five in the control group.

Haemophilus aphrophilus endocarditis

We report a case of Haemophilus aphrophilus endocarditis involving mitral and tricupsid valves in a boy with congenital heart disease. He had received dental treatment without antibiotic cover. Prolonged high-dose ampicillin with gentamicin was necessary for cure. Short courses of ampicillin alone may not successfully treat H. aphrophilus.

Preoperative assessment for practicing oral and maxillofacial surgeons

A three-day workshop was designed for practicing oral and maxillofacial surgeons to review the clinical skills needed for preoperative assessment. The intent of the workshop was to prepare participants for broader hospital privileges under the new recommendations of the Joint Commission on Accreditation of Hospitals. The course was characterized by small group interaction and team-teaching involving physicians and oral and maxillofacial surgeons. Instruction included observation of simulated cases, a review of the documentation of such encounters, lecture-discussions, and examination of patients with positive physical findings.

The measurement of blood pressure and its interpretation

The auscultatory or indirect technique of measuring blood pressure has been proved reliable in multiple clinical settings and has received wide application. In clinical studies, special efforts are used to train observers in the measurement of blood pressure and to ensure properly functioning equipment. Similar diligence in providing quality control is necessary in everyday practice to guard against potential errors. With proper care it is possible to obtain readings that classify the pressure to the nearest 5 mm Hg. Table 1 lists some of the sources of error that are possible with the indirect technique and the magnitude of these errors. It should be emphasized that many factors affect blood pressure variation and that any single reading is of limited value. A number of specific sources of information are useful to the practicing physician and his staff for maintaining equipment and for standardizing technique and procedure. Application of these principles to primary care practice should improve the accuracy of health maintenance and allow proper clinical application of the results of the many clinical studies of mild hypertension that are presently being conducted around the world.