Examining the Awareness, Acceptability, and Adoption of Conventional and non-conventional Forms of Pre-Exposure Prophylaxis (PrEP) for HIV Prevention Among jail-involved Black Sexual Minority men (BSMM) and Black Transgender Women (BTW) in Two Diverse US Cities

Black sexual minority men (BSMM) and Black transgender women (BTW) are disproportionately impacted by HIV and incarceration in the United States. In-depth interviews (N=34) and ongoing thematic analysis guided by the Exploration Phase of the Exploration, Preparation, Implementation, Sustainment framework were conducted to uncover key themes focused on the awareness, acceptability, and early adoption of conventional (i.e., daily oral pill) and non-conventional forms of PrEP (i.e., long-acting injectable, e-prescription for pick up post release) among jail-involved BSMM and BTW in Chicago, Illinois and Baton Rouge, Louisiana. The majority of participants were cisgender BSMM (88%) and were enrolled in Chicago (65%). There was greater awareness, availability, and adoption of conventional PrEP and non-conventional PrEP e-prescription for pick up post release among Chicago participants compared with Baton Rouge participants. Participants were largely receptive to all three forms of PrEP and stated a high need for HIV prevention in jails and immediately following release. PrEP stigma emerged as a major barrier to conventional daily PrEP adoption while incarcerated; potential misuse (e.g., pill selling) as a potential barrier to PrEP eprescription; and needle aversion and added clinic time as potential barriers to longacting injectable (LAI)-PrEP. Participants indicated that PrEP e-prescription could help support continuity of care post release and highlighted reduced stigma, convenience, and longer-term HIV protection as benefits for LAI-PrEP. Study findings provided context-specific information to inform the implementation of future PrEP interventions for jail-involved BSMM and BTW in two highly HIV-impacted jurisdictions.

Experimental verification of principal losses in a regulatory particulate matter emissions sampling system for aircraft turbine engines

A sampling system for measuring emissions of nonvolatile particulate matter (nvPM) from aircraft gas turbine engines has been developed to replace the use of smoke number and is used for international regulatory purposes. This sampling system can be up to 35 m in length. The sampling system length in addition to the volatile particle remover (VPR) and other sampling system components lead to substantial particle losses, which are a function of the particle size distribution, ranging from 50 to 90% for particle number concentrations and 10-50% for particle mass concentrations. The particle size distribution is dependent on engine technology, operating point, and fuel composition. Any nvPM emissions measurement bias caused by the sampling system will lead to unrepresentative emissions measurements which limit the method as a universal metric. Hence, a method to estimate size dependent sampling system losses using the system parameters and the measured mass and number concentrations was also developed (SAE 2017; SAE 2019). An assessment of the particle losses in two principal components used in ARP6481 (SAE 2019) was conducted during the VAriable Response In Aircraft nvPM Testing (VARIAnT) 2 campaign. Measurements were made on the 25-meter sample line portion of the system using multiple, well characterized particle sizing instruments to obtain the penetration efficiencies. An agreement of ± 15% was obtained between the measured and the ARP6481 method penetrations for the 25-meter sample line portion of the system. Measurements of VPR penetration efficiency were also made to verify its performance for aviation nvPM number. The research also demonstrated the difficulty of making system loss measurements and substantiates the E-31 decision to predict rather than measure system losses.

Education and clinical decision support for healthcare professionals on emergency preparedness for extremely dangerous pathogens: report of a conference workshop

Clinical decision support and e-learning will be essential if we are to achieve the goal of preventing outbreaks of infectious diseases caused by extremely dangerous pathogens. However, these resources on their own will not be enough to achieve this outcome. To achieve this outcome, resources must be integrated into undergraduate and postgraduate educational curricula, accredited as part of continuous professional development programmes, built around the knowledge and skills gaps of learners and developed using an evidence-based methodology that will enable healthcare professionals to put their learning into action for the benefit of both patients and populations. This article describes and contextualises the personal views discussed at a workshop on education and clinical decision support for healthcare professionals reacting to an infectious disease outbreak from extremely dangerous pathogens.

A Study to Investigate the Role of GULP/ CED 6 Gene in "Eat Me" Signaling in Cellular Efferocytosis and Immunosurveillance

In this report, investigations were done to study human GULP/ CED 6 genes role in presenting cancer cells to scavenger cells. CED 6 SiRNA was used to knock out the gene in Astrocytoma (HTB-12) cell lines to study its effects on expression of various "eat me" signals on these cells including Phosphatidyl serine (PtdSer) expression, nitric oxide (NO) signaling and Leukotrine B4 (LTB4) expression and Caspase 3 activation. Investigations were done by fluorescence microscopy techniques, ELISA assay and colorimetric assays using a standard microplate reader and spectrophotometer. Initial results showed all the above mentioned "eat me" signals were significantly decreased in CED 6 knock out cell lines. Therefore CED 6 gene must have a role in cancer cell clearance, pathway involved in the cross talk between CED 6 and other genes in this process is a matter of farther investigation.

Breast dynamic contrast-enhanced examinations with fat suppression: are contrast-agent uptake curves affected by magnetic field inhomogeneity?

OBJECTIVES

To investigate the effect of magnetic field heterogeneity in breast dynamic contrast-enhanced examinations with fat saturation (DCE-FS).

METHODS

The magnetic field was mapped over the breasts in ten patients. DCE-FS was undertaken at 1.5 T with fast spoiled gradient echoes and spectrally selective fat saturation. Signal intensity was calculated for T1 values 25-1,200 ms both on and off resonance, and results were verified with a test object. Clinical examinations were evaluated for the predicted effects of field heterogeneity.

RESULTS

Magnetic field was found to vary by 3.6 ± 1.2 ppm over the central transaxial slice and 5.1 ± 1.5 over the whole breast volume (mean ± standard deviation). Computer simulations predict a reduction in the dynamic range if field heterogeneity leads to unintended water suppression, and distortion to CA uptake curves due to fat suppression failure (for fat containing pixels). A compromise between dynamic range and fat saturation performance is required. Both water suppression and fat suppression failure are apparent in clinical examinations.

CONCLUSION

Magnetic field heterogeneity is likely to reduce the sensitivity of DCE-FS by distorting the CA uptake curves because of fat suppression failure (for fat containing pixels) and by reducing the dynamic range because of unintended water suppression.

KEY POINTS

• Magnetic field heterogeneity is significant in breast magnetic resonance. • Contrast-agent uptake curves are distorted by a non-uniform magnetic field. • Radiologist must be aware of possibility of distortion to interpret uptake curves correctly. • Compromise between fat suppression and dynamic range is required.

Climate change impacts on mycotoxin risks in US maize

To ensure future food security, it is crucial to understand how potential climate change scenarios will affect agriculture. One key area of interest is how climatic factors, both in the near- and the long-term future, could affect fungal infection of crops and mycotoxin production by these fungi. The objective of this paper is to review the potential impact of climate change on three important mycotoxins that contaminate maize in the United States, and to highlight key research questions and approaches for understanding this impact. Recent climate change analyses that pertain to agriculture and in particular to mycotoxigenic fungi are discussed, with respect to the climatic factors – temperature and relative humidity – at which they thrive and cause severe damage. Additionally, we discuss how climate change will likely alter the life cycles and geographic distribution of insects that are known to facilitate fungal infection of crops.

The 'omics' tools: genomics, proteomics, metabolomics and their potential for solving the aflatoxin contamination problem

Aflatoxins are highly carcinogenic secondary metabolites produced primarily by the fungi Aspergillus flavus and Aspergillus parasiticus. Aflatoxin contamination of food and feed is an age old problem of particular concern over the last four decades. Now, for the first time control measures for this problem appear within reach. For practical and sustainable control of aflatoxin contamination to be realised, however, additional information is needed rather rapidly, particularly for understanding the specific molecular factors (both in the plant and the fungus) involved during host plant-fungus interaction. The information derived from the use of novel tools such as genomics, proteomics and metabolomics provides us with the best and the quickest opportunity to achieve a clear understanding of the survival of toxigenic fungi in the field, the ability of the fungus to invade crops, and the process of toxin contamination under various environmental conditions. Significant progress has been made recently in understanding the genomic makeup of the most significant aflatoxin producing field fungus, namely Aspergillus flavus. Progress also has been made in the study of host crop resistance to fungal invasion through the use of proteomics. The information available on production of aflatoxin and other metabolites by Aspergillus flavus is reasonably extensive, although the application of metabolomics as a tool in this study is relatively new. In this review there is a discussion of the use of genomics, proteomics and metabolomics in deriving the requisite information for developing effective strategies to interrupt the machinery in the fungus for production of these toxins, as well as to assist in the development of host-resistance against fungal invasion and aflatoxin contamination of crops.

What can comparative genomics tell us about species concepts in the genus Aspergillus?

Understanding the nature of species" boundaries is a fundamental question in evolutionary biology. The availability of genomes from several species of the genus Aspergillus allows us for the first time to examine the demarcation of fungal species at the whole-genome level. Here, we examine four case studies, two of which involve intraspecific comparisons, whereas the other two deal with interspecific genomic comparisons between closely related species. These four comparisons reveal significant variation in the nature of species boundaries across Aspergillus. For example, comparisons between A. fumigatus and Neosartorya fischeri (the teleomorph of A. fischerianus) and between A. oryzae and A. flavus suggest that measures of sequence similarity and species-specific genes are significantly higher for the A. fumigatus - N. fischeri pair. Importantly, the values obtained from the comparison between A. oryzae and A. flavus are remarkably similar to those obtained from an intra-specific comparison of A. fumigatus strains, giving support to the proposal that A. oryzae represents a distinct ecotype of A. flavus and not a distinct species. We argue that genomic data can aid Aspergillus taxonomy by serving as a source of novel and unprecedented amounts of comparative data, as a resource for the development of additional diagnostic tools, and finally as a knowledge database about the biological differences between strains and species.

Concurrent comparison of three water contact measurement tools in four endemic villages of the Philippines. The schistosomiasis transmission ecology in the Philippines project (STEP)

BACKGROUND

Schistosomiasis japonica is a chronic helminthic infection contracted through contact with water infested with Schistosoma japonicum. The infection is associated with severe disease and is an important public health concern in Philippines.

OBJECT

To estimate the agreement in the frequency of water contact between bimonthly interviews, self-administered diaries and observations.

METHODS

A total of 286 individuals were followed over either a 4 or a 6 months period. Agreement between direct observation and both the bimonthly and diary methods were estimated.

RESULTS

The agreement between the observation and the bimonthly interview was 71.8% when days without any water contacts were considered, but decreased to 23.3% when only days with at least some water contact were considered. The agreement between the observation and the diary was 78.7% when days without any water contacts were considered and 40.8% when only days with some water contacts were considered.

CONCLUSIONS

Agreement about the degree of water contact is poor between the different measurement tools. This has important implications for future research, since a high degree of measurement error can severely bias any results from studies involving water contact.

Management and outcomes of acute coronary syndrome with minimal myocardial necrosis: analysis of a large prospective registry from a non-interventional centre

The aim of this study was to assess the clinical risk of minimal myonecrosis below the cut-off for acute myocardial infarction (MI) in comparison with other grades of acute coronary syndrome (ACS). One-thousand four hundred and sixty seven consecutive patients with ACS admitted between May 2001 and April 2002 were studied in a non-interventional centre. Patients were divided into unstable angina (UA) (cTnT < 0.01 microg/l), non-ST elevation ACS with minimal myonecrosis (0.01 <or= cTnT < 0.1 microg/l), non-ST elevation MI (NSTEMI) (cTnT >or= 0.1 microg/L) and ST elevation myocardial infarction (STEMI). UA (n = 638) was associated with the fewest events at 6 months (2% cardiac death or MI). Patients with any myonecrosis (n = 829) had worse outcomes (6-month cardiac death or MI 18.3-23.3%). Compared with ACS patients with minimal myonecrosis, UA patients were at significantly lower risk (OR 0.21, 95% CI 0.12-0.45, p < 0.001), NSTEMI patients were at similar risk (OR 1.45, 95% CI 0.89-2.35, p = 0.13), and STEMI patients were at higher risk (OR 2.12 95% CI 1.26-3.85, p = 0.008) in adjusted analyses. Nearly 85% of cardiac deaths occurred within 6 months. The risk of adverse events was higher among patients managed by non-cardiologists (OR 1.66, 95% CI 1-2.75, p = 0.049). Patients with non-ST elevation ACS and minimal myonecrosis are a high-risk group more comparable with NSTEMI and clearly distinguishable from patients with UA.

Participant recruitment in the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)

The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) is a practice-based, randomized, multicenter clinical trial in 42,419 high-risk hypertensive patients aged 55 years and older; 10,356 of these patients are also in a lipid-lowering trial component. The purpose of the antihypertensive component is to determine whether the occurrence of fatal coronary heart disease and/or nonfatal myocardial infarction differs between patients randomized to diuretic (chlorthalidone) and those randomized to either calcium antagonist (amlodipine), angiotensin-converting enzyme inhibitor (lisinopril), or alpha-adrenergic blocker (doxazosin) therapy. (The doxazosin arm has been discontinued.) The purpose of the lipid-lowering component is to determine whether lowering low-density lipoprotein cholesterol with a 3-hydroxymethyl-glutaryl coenzyme A reductase inhibitor (pravastatin) in moderately hypercholesterolemic patients will reduce all-cause mortality compared to a control group receiving "usual care." ALLHAT recruited patients from a variety of practice settings from February 1994 through January 1998. Sites were paid for randomizations and are paid for completed follow-up visits and documented study events. Communication and monitoring were facilitated by nine regional coordinator teams. It was recognized from the outset that patient recruitment would be a very large task because of the number of participants (> 40,000) needed, the ambitious nature of the goal for recruitment of African-Americans (> 55%), and the knowledge that many investigators had limited experience recruiting participants for clinical trials. Multiple adjustments in the initial ALLHAT overall recruitment plan facilitated achievement of sample size goals for both components of the trial. The experience obtained from this large trial should be valuable for the planning and implementation of successful recruitment in future trials.

Growth factors inactivate the cell death promoter BAD by phosphorylation of its BH3 domain on Ser155

The Bcl-2 family protein BAD promotes apoptosis by binding through its BH3 domain to Bcl-x(L) and related cell death suppressors. When BAD is phosphorylated on either Ser(112) or Ser(136), it forms a complex with 14-3-3 in the cytosol and no longer interacts with Bcl-x(L) at the mitochondria. Here we show that phosphorylation of a distinct site Ser(155), which is at the center of the BAD BH3 domain, directly suppressed the pro-apoptotic function of BAD by eliminating its affinity for Bcl-x(L). Protein kinase A functioned as a BAD Ser(155) kinase both in vitro and in cells. BAD Ser(155) was found to be a major site of phosphorylation induced following stimulation by growth factors and prevented by protein kinase A inhibitors but not by inhibitors of the phosphatidylinositol 3-kinase/Akt pathway. Growth factors inhibited BAD-induced apoptosis in both a Ser(112)/Ser(136)- and a Ser(155)-dependent fashion. Thus, growth factors engage an anti-apoptotic signaling pathway that inactivates BAD by direct modification of its BH3 cell death effector domain.

Proton magnetic resonance spectroscopy ((1)H-MRS) of the brain following high-dose methotrexate treatment for childhood cancer

BACKGROUND

To avoid the late sequelae associated with cranial radiation therapy in childhood, intermediate- or high-dose intravenous methotrexate (HDMTX) has found increasing application as a means of preventing the development of overt central nervous system disease in childhood acute leukaemia. However, acute and chronic neurotoxicity has been described following HDMTX therapy, and the long-term intellectual outcome in children treated in this way is inadequately documented. Proton magnetic resonance spectroscopy ((1)H-MRS) of the brain is a noninvasive, quantitative way of assessing aspects of cerebral metabolism, which has not previously been applied to the study of children undergoing central nervous system directed therapy.

PROCEDURE

To evaluate the potential role of (1)H-MRS in the investigation of related neurotoxicity, 11 children who had received HDMTX (cumulative dose 6-96 g/m(2)) underwent localised (1)H-MRS, magnetic resonance imaging. Neuropsychological assessments were performed on the children who had more than 1 year of follow-up time since last methotrexate treatment. Control (1)H-MRS studies on 11 adult and 6 young volunteers were undertaken. Eight patients had spectra of adequate quality. Comparisons between (1)H-MRS metabolite ratios and normal controls were made.

RESULTS

Patients had a low choline/water ratio compared to controls (P < 0.01). No differences between patient and control NAA/water, Cr/water, Naa/Cr, and Cho/Cr ratios were seen. Overall, 3 patients had abnormal white matter changes on MRI. The mean IQ of the patients (104.1) was in the normal range.

CONCLUSIONS

It is postulated that choline depletion in the brains of these patients may reflect subclinical disturbances of myelin metabolism as a result of methotrexate therapy and may represent a possible avenue of treatment in patients with clinical chronic methotrexate-related neurotoxicity.

Re-engineering the soft machine: the impact of developing technology and changing practice on diagnostic radiographer skill requirements

This paper describes research to investigate the extent to which new technology and changing work practices in diagnostic imaging have changed the skill requirements of working radiographers. Interviews were conducted with radiography managers, radiologists and industry representatives. While changes in technology were viewed as having a significant impact on skill requirements, levels of resourcing and both national and local policy were seen as key factors driving changes in work practice. Respondents believed that significant changes would be required to pre- and post-registration training requirements for radiographers in the light of changing practice.

Socio-economic re-structuring and employment: the case of minority ethnic groups

The consequences of major changes in employment, due to the decline of manufacturing and the growth of the service sector, have not been well-documented, nor theorized, in the sociology of ethnic relations, even in recent studies. For example, Blumer's classic argument that economic development adapts to 'race relations', rather than the reverse as predicted by the modernization school, has not been either empirically resolved or conceptually applied to the UK. By adapting data from the Labour Force Survey and the Census, the paper begins to fill this gap with a detailed account of three main minority ethnic groups, and a separate analysis of male and female employment. It is demonstrated that, contrary to assumptions that members of the minority ethnic groups suffered most from de-industrialization, they actually did rather well, and in some cases did better than the majority population. These findings are re-conceptualized as collective social mobility, as part of a review of a number of conceptual frameworks in the light of the data.

Expression of the insulin-like growth factor I receptor C terminus as a myristylated protein leads to induction of apoptosis in tumor cells

The insulin-like growth factor I receptor (IGF-IR) has been shown to mediate mitogenesis and suppression of apoptosis. Certain mutations in the COOH terminus of the receptor abrogate the antiapoptotic activity but not the mitogenic activity. However, truncation of the receptor by deletion of the COOH-terminal 108 amino acids enhances suppression of apoptosis by the IGF-IR, which suggests that the COOH terminus has a negative regulatory role. To investigate this further, a series of mammalian expression vectors were generated that encoded either the COOH terminus of the receptor or the COOH terminus plus the kinase domain. In some cases, the first 16 amino acids of SRC were included at the NH2 terminus to provide a site for myristylation. In transient transfection assays, the membrane-targeted COOH-terminal construct, MyCF, was found to induce apoptosis in MCF-7 breast carcinoma cells and C6 glioblastoma cells, whereas the COOH-terminal construct without the myristylation signal, CF, was poorly cytotoxic. MyKCF, which encodes the kinase domain as well as the COOH terminus, had intermediate cytotoxicity. The cytotoxicity of MyCF was diminished by point mutations that were previously shown to abrogate suppression of apoptosis in the context of the full-length receptor. MCF-7 cells stably expressing the CF or the MyCF proteins exhibited decreased clonogenicity in soft agar and increased sensitivity to UV irradiation. These results indicate that expression of the IGF-IR COOH terminus promotes apoptosis of tumor cells, possibly by interfering with signals necessary for cell survival.

The optimal pacing rate: an unpredictable parameter

A three phase relation has been demonstrated between increasing heart rate and cardiac output at rest. Phase I with cardiac output increasing with increasing heart rate, phase II a plateau, and phase III decreasing cardiac output with any further increase in heart rate. The "optimal rate" can be defined as the heart rate at the onset of phase II. Twenty patients were studied, 13 male, mean age 60 years (range 31-71 years). All had chronic complete heart block and established DDD pacing. A maximal exercise test was performed to determine peak sinus rate. Exercise hemodynamics were measured using an ambulatory monitor (Capintec Vest), which permits measurement of relative cardiac output and relative ejection fraction. The patients were programmed to VVI pacing at a rate of 60 beats/min and performed three exercise tests at different workloads. The order of workloads was randomized and selected from a range (0, 25, 50, or 75 W) depending on fitness. After 3-minute stabilization, the VVI pacing rate was increased at 1-minute intervals until higher than peak sinus rate giving a total exercise time of 12 minutes. The "optimal rate band" was determined at each workload. The mean of this "optimal rate band" for each workload varied in a nonlinear manner. There was no correlation between "mean optimal rate" and age or the peak rate predicted by the Astrand formula. Current definitions of chronotropic incompetence are inaccurate. Are some of these people at their "optimal rate" already? The arbitrary selection of rate response curves on age related criteria may lead to an impaired hemodynamic response.

Outcome-based practice: disclosure rates of child sexual abuse comparing allegation blind and allegation informed structured interviews

The way in which children are interviewed can make the difference between prosecution, or continued abuse. There is a clear need for the development of an interview style that is acceptable in the legal system without compromising disclosure rate. This study was conducted to compare the disclosure rate of alleged child sexual abuse victims interviewed in a formal forensic setting with a structured "allegation informed" technique versus a structured "allegation blind" technique. The only difference between techniques was that the interviewer did not know the allegation for condition "allegation blind." Of the 1,535 interviews, 1,330 or 86.64% were conducted "allegation blind," 196 or 12.76% were conducted "allegation informed" and for 9 or .6% the interview type was unknown. The "allegation blind" interview technique yielded a statistically higher disclosure rate (chi 2 p = 0.378). Further research is warranted.

Posttranslational modifications of meningococcal pili. Identification of a common trisaccharide substitution on variant pilins of strain C311

Neisseria meningitidis pili are filamentous protein structures that are essential adhesins in capsulate bacteria. Pili of adhesion variants of meningococcal strain C311 contain glycosyl residues on pilin (PilE), their major structural subunit. Recent studies have shown that a novel O-linked trisaccharide substituent, not previously found as a constituent of glycoproteins, is present within a peptide spanning amino acid residues 50 to 73 of the PilE molecule. The structure was shown to be Gal beta 1-4 Gal alpha 1-3 diacetamidotrideoxyhexose which is directly attached to pilin. Pilins derived from galactose epimerase (galE) mutants lack the digalactosyl moiety, but retain the diacetamidotrideoxyhexose substitution. These studies confirm our previous observations that meningococcal pili are glycosylated and provide the first structural evidence for the presence of covalently linked carbohydrate on pili. We have identified a completely novel protein/carbohydrate linkage on a multimeric protein that is an essential virulence determinant in N. meningitidis.

Discovery of a novel protein modification: alpha-glycerophosphate is a substituent of meningococcal pilin

Pili, which are filamentous protein structures on the surface of the meningitis-causing organism Neisseria meningitidis, are known to be post-translationally modified with substituents that affect their mobility in SDS/PAGE and which might play a crucial role in adherence and bloodstream invasion. Tryptic digests of pili were analysed by fast atom bombardment and electrospray MS to identify putative modifications. Serine-93 was found to carry a novel modification of alpha-glycerophosphate. This is the first time that alpha-glycerophosphate has been observed as a substituent of a prokaryotic or eukaryotic protein.

Erythropoietin treatment of erythropoietin-deficient anemia without renal disease during pregnancy

BACKGROUND

The use of recombinant human erythropoietin in pregnancy has been described in patients with renal impairment. We present a patient with a hypoproliferative anemia with low serum erythropoietin levels and no renal disease or other known cause for this type of anemia, who was treated with recombinant human erythropoietin.

CASE

A 29-year-old white woman who became pregnant after leuprolide acetate and menopausal gonadotropin therapy developed a moderate anemia (hemoglobin 8.5 g/dL) in early pregnancy. The only important laboratory findings were a hypoproliferative marrow and a low serum erythropoietin level. She was treated successfully with injections of recombinant human erythropoietin. Her pregnancy was otherwise uncomplicated and her pre-delivery hemoglobin level was 12 g/dL.

CONCLUSION

Hypoproliferative anemia in pregnancy with low erythropoietin levels and no renal disease can be treated successfully with recombinant human erythropoietin.

Meningococcal pilin: a glycoprotein substituted with digalactosyl 2,4-diacetamido-2,4,6-trideoxyhexose

Neisseria meningitidis pili are filamentous protein structures that are essential adhesins in capsulate bacteria. Pili of adhesion variants of meningococcal strain C311 contain glycosyl residues on pilin (PilE), their major structural subunit. Despite the presence of three potential N-linked glycosylation sites, none appears to be occupied in these pilins. Instead, a novel O-linked trisaccharide substituent, not previously found as a constituent of glycoproteins, is present within a peptide spanning amino acid residues 45 to 73 of the PilE molecule. This structure contains a terminal 1-4-linked digalactose moiety covalently linked to a 2,4-diacetamido-2,4,6-trideoxyhexose sugar which is directly attached to pilin. Pilins derived from galactose epimerase (galE) mutants lack the digalactosyl moiety, but retain the diacetamidotrideoxyhexose substitution. Both parental (#3) pilins and those derived from a hyper-adherent variant (#16) contained identical sugar substitutions in this region of pilin, and galE mutants of #3 were similar to the parental phenotype in their adherence to host cells. These studies have confirmed our previous observations that meningococcal pili are glycosylated and provided the first structural evidence for the presence of covalently linked carbohydrate on pili. In addition, they have revealed a completely novel protein/saccharide linkage.

Modification of Ser59 in the unique N-terminal region of tyrosine kinase p56lck regulates specificity of its Src homology 2 domain

During T-cell activation, Ser59 in the unique N-terminal region of p56lck is phosphorylated. Mutation of Ser59 to Glu59 mimics Ser59 phosphorylation, and upon CD4 crosslinking, this mutant p56lck induces tyrosine phosphorylation of intracellular proteins distinct from those induced by wild-type p56lck. Mutant and wild-type p56lck have similar affinities for CD4 and similar kinase activities. In glutathione S-transferase fusion proteins, the p56lck Src homology 2 (SH2) domain with the SH3 domain and the unique N-terminal region (including Ser59) has a different binding specificity for phosphotyrosyl proteins than the SH2 domain alone. Either deletion of the unique N-terminal region or mutation of Ser59 to Glu59 in the fusion protein reverts the phosphotyrosyl protein binding specificity back to that of the SH2 domain alone. These results suggest that phosphorylation of Ser59 regulates the function of p56lck by controlling binding specificity of its SH2 domain.

Functional implications of the expression of PilC proteins in meningococci

Multiple forms of PilC were found in Neisseria meningitidis (Nm) strains isolated from the oropharynx, blood or cerebrospinal fluid expressing either Class I or Class II pili. PilC expression was observed less frequently in case as opposed to carrier isolates. Moreover, PilC and pili were not always co-expressed. Several heavily piliated strains had no detectable PilC protein as determined by Western blotting using an antiserum previously used to detect such proteins in adhesive variants (Nassif et al., 1994). Serogroup B strain MC58 produced large numbers of pili, but expressed barely detectable amounts of PilC. A clonal variant of this strain with increased expression of PilC concurrently exhibited increased adherence to Chang conjunctival epithelial cells and human umbilical vein endothelial cells (Huvecs), but with more rapid binding to the former. No alteration in pilin sequence occurred in this variant, suggesting the involvement of PilC in increased adhesion. A Pil- backswitcher isolated from the hyper-adherent variant was PilC+ but was non-adherent, indicating that any PilC adherence function requires pilus expression. Parental variant (low PilC) produced pili in bundles that were easily detached from the bacterial surface and were frequently associated with Huvec surfaces after bacteria had been sheared off, but pili infrequently replaced bacteria during infection with the PilC-expressing variant. The hyper-adherent variant, which appeared to produce morphologically distinct pilus bundles, was able to withstand considerable shearing force and remained firmly attached to Huvecs. This raises the possibility that the observed hyper-adherence may arise from better anchorage of pili to the bacterial surface in addition to increased adhesion to some host cell surfaces.

Usefulness of culture in the diagnosis of Clostridium difficile infection

Between January and April 1993, culture for Clostridium difficile and a faecal cytotoxin assay were performed on 500 selected specimens. Isolates from culture-positive patients from whom faecal samples were cytotoxin negative were also examined in vitro for cytotoxin production. The significance of a positive culture result in the absence of faecal cytotoxin was assessed. Forty-one of the 500 specimens were toxin positive. In only 25 of these was Clostridium difficile examination specifically requested. Six of nine culture-positive cytotoxin-negative patients (11 specimens) had recently received antibiotics. In four of these, Clostridium difficile was considered to be of possible clinical significance. Culture and in vitro determination of toxin production of isolates may aid in the diagnosis of some additional cases, but cytotoxin detection remains the single optimal routine laboratory method for diagnosis.

Mother-daughter correlations of obesity and cardiovascular disease risk factors in black and white households: the NHLBI Growth and Health Study

OBJECTIVES

This study sought to evaluate obesity as a potential explanatory factor for the increased relative risk for cardiovascular disease in Black compared with White women.

METHODS

Familial associations for obesity and cardiovascular disease risk factors were assessed in 720 White and 580 Black mother-daughter pairs from the National Heart, Lung, and Blood Institute's Growth and Health Study by using Pearson's chi square, Spearman's correlations, and partial correlations.

RESULTS

Black girls and mothers were significantly heavier and had higher body mass indices than their White counterparts. In each racial group, significant, positive mother-daughter correlations existed for weight, body mass index, and triceps skinfolds, and for all cardiovascular disease risk factors. Obesity measures correlated positively with systolic blood pressure and triglycerides and inversely with high-density lipoprotein cholesterol in girls and mothers of both races. Correlations between mothers and daughters for exercise and ideal body shape were weak and did not explain obesity associations.

CONCLUSIONS

Intrafamilial associations of obesity, cardiovascular disease risk factors, and the obesity-cardiovascular disease risk factor relationship support the position that increased cardiovascular disease morbidity and mortality rates in Black women may be linked to excess obesity in Black women compared with White ones.

The phosphopeptide-binding specificity of Src family SH2 domains

BACKGROUND

Src homology 2 (SH2) domains mediate protein/protein interactions by binding phosphotyrosyl proteins with high specificity. The protein Lck, a Src-like lymphocyte-specific tyrosine kinase which is important in signals involved in T-cell development, contains one such domain. The crystal structure of a complex of the Lck SH2 domain with a high-affinity ligand, pY324, is known. This ligand has the sequence EPQpYEEIPIYL.

RESULTS

We designed and synthesized a series of phosphopeptides with single amino-acid changes in the four residues C-terminal to the phosphotyrosine (pTyr) in pY324. Surprisingly, the Glu one residue C-terminal to the phosphotyrosine (at position pY + 1) is sensitive to substitution, whereas the Ile at position pY + 3 is much less sensitive, accommodating a Glu with only modest loss of binding affinity. Replacement of the Glu and Pro on either side of the Ile had little effect, as predicted. Truncated phosphopeptides that end at position pY + 5 and have only an acetyl group N-terminal to the pTyr bound with only slightly lower affinity than pY324. In addition, naturally occurring phosphopeptide sequences that span a 1,000-fold range in binding affinity for the Lck SH2 domain have been identified.

CONCLUSIONS

The Lck SH2 domain is highly selective for phosphotyrosyl-peptide binding; its specificity is dictated by the first and third residues C-terminal to the pTyr. The unexpected effects of some amino-acid substitutions indicate that the interactions seen between SH2 domains and ligand in the crystal structure may not be identical to those that occur in solution.

Physical and functional interactions between SH2 and SH3 domains of the Src family protein tyrosine kinase p59fyn

The Src family protein tyrosine kinases participate in signalling through cell surface receptors that lack intrinsic tyrosine kinase domains. All nine members of this family possess adjacent Src homology (SH2 and SH3) domains, both of which are essential for repression of the enzymatic activity. The repression is mediated by binding between the SH2 domain and a C-terminal phosphotyrosine, and the SH3 domain is required for this interaction. However, the biochemical basis of functional SH2-SH3 interaction is unclear. Here, we demonstrate that when the SH2 and SH3 domains of p59fyn (Fyn) were present as adjacent domains in a single protein, binding of phosphotyrosyl peptides and proteins to the SH2 domain was enhanced, whereas binding of a subset of cellular polypeptide ligands to the SH3 domain was decreased. An interdomain communication was further revealed by occupancy with domain-specific peptide ligands: occupancy of the SH3 domain with a proline-rich peptide enhanced phosphotyrosine binding to the linked SH2 domain, and occupancy of the SH2 domain with phosphotyrosyl peptides enhanced binding of certain SH3-specific cellular polypeptides. Second, we demonstrate a direct binding between purified SH2 and SH3 domains of Fyn and Lck Src family kinases. Heterologous binding between SH2 and SH3 domains of closely related members of the Src family, namely, Fyn, Lck, and Src, was also observed. In contrast, Grb2, Crk, Abl, p85 phosphatidylinositol 3-kinase, and GTPase-activating protein SH2 domains showed lower or no binding to Fyn or Lck SH3 domains. SH2-SH3 binding did not require an intact phosphotyrosine binding pocket on the SH2 domain; however, perturbations of the SH2 domain induced by specific high-affinity phosphotyrosyl peptide binding abrogated binding of the SH3 domain. SH3-SH2 binding was observed in the presence of proline-rich peptides or when a point mutation (W119K) was introduced in the putative ligand-binding pouch of the Fyn SH3 domain, although these treatments completely abolished the binding to p85 phosphatidylinositol 3-kinase and other SH3-specific polypeptides. These biochemical SH2-SH3 interactions suggest novel mechanisms of regulating the enzymatic activity of Src kinases and their interactions with other proteins.

Thoracic impedance and pulmonary atrial natriuretic peptide during head-up tilt induced hypovolaemic shock in humans

Head up and down tilts were used for manipulating the central blood volume in eight volunteers. During head-up tilt thoracic electrical impedance (TI) increased from 36.7 (33.9-52.1) ohm (mean and range) to 41.9 (36.9-59.2) ohm, heart rate from 60 (49-72) to 80 (65-90) beats min-1 (P < 0.05) and decreased again to 57 (48-67) beats min-1 accompanying a fall in mean arterial pressure from 86 (76-97) to 54 (41-79) mmHg and in cardiac output from 9.2 (5.9-12.1) to 6.9 (3.4-8.8) 1 min-1 (n = 7, P < 0.07). Central venous pressure did not change significantly. Pulmonary arterial mean, 6 (3-12) mmHg, and wedge pressures, 4 (1-9) mmHg, decreased to 4 (1-11) and 1 (0-7) mmHg, respectively, and mixed, 78 (77-79%), and central venous oxygen saturations, 72 (71-73)%, fell to 62 (46-75) and 54 (44-58)%, respectively (P < 0.05). Atrial natriuretic peptide (ANP) was determined from blood of the superior vena cava and pulmonary and brachial arteries. Pulmonary artery ANP, 18.4 (7.5-30.7) pmol l-1, was higher than in vena cava, 13.3 (5.2-20.9) pmol l-1 (P < 0.05). At the time of presyncope, pulmonary artery ANP decreased from 20.8 (37.4-10.1) to 13.7 (19.7-5.7) pmol l-1, in vena cava from 13.8 (23.1-7.1) to 10.2 (17.9-6.7) pmol l-1 and in the brachial artery from 16.9 (34.1-5.2) to 11.3 (18.5-5.1) pmol l-1 (P < 0.05). Head-down tilt did not affect the recorded variables significantly. Thoracic electrical impedance, pulmonary artery pressure and venous oxygen saturations were sensitive indices of the central blood volume as reflected in the release of atrial natriuretic peptide from the right side of the heart.

Kinetics of p56lck and p60src Src homology 2 domain binding to tyrosine-phosphorylated peptides determined by a competition assay or surface plasmon resonance

Src homology 2 (SH2) domains are phosphotyrosine-binding modules found within various signal-transducing proteins. We have determined by 125I competition assay and surface plasmon resonance that the SH2 domains of Src and Lck bind to a variety of phosphopeptides with similar affinity and specificity. Both bound with highest affinity [Kd(app) approximately 3.7 nM; ka = 2.4 x 10(5) M-1 x s-1; kd = 1.2 x 10(-3) s-1] a phosphopeptide having a Tyr(P)-Glu-Glu-Ile motif found in the hamster polyomavirus middle-sized tumor antigen. Intermediate affinity (5- to 40-fold lower) was observed with phosphopeptides corresponding to the regulatory domains of Src and Lck, containing Tyr527 and Tyr505, respectively. Lowest affinity (80- to 300-fold lower) was observed with phosphopeptides corresponding to phosphorylated tyrosines of GTPase-activating protein, insulin receptor substrate 1, and SH2 domain-containing protein-tyrosine-phosphatase 1.

An indifference point for electrical impedance in humans

Regional electrical impedance was used over eight sections of the human body (two thoracic; one abdominal; two thigh; two around the knee; and one lower leg) to determine the volume indifference point during passive head-up tilt in eight subjects. Head-up tilt was performed in 10 degrees increments from 0 degree to 60 degrees over 6 min. Electrical impedance increased over the thorax in proportion to the head-up tilt angle, while abdominal impedance did not change significantly, and over the thigh and the lower leg it decreased with increasing head-up tilt angle. No change in electrical impedance was noted just above the knee, and electrical impedance just below the knee decreased only marginally. Results demonstrate minimal fluid accumulation around the knee during head-up tilt. Furthermore, in humans the electrical impedance and therefore probably the volume indifference point is positioned between the umbilicus and crista iliaca.

Effect of limb anesthesia on middle cerebral response to handgrip

Transcranial Doppler ultrasound was used to measure middle cerebral arterial mean flow velocity (Vmean) on both sides of the brain in 12 subjects during hand contractions before and during regional anesthesia of the left arm. At rest Vmean was 49 (36-104) cm/s (median and range) and was unaffected by regional anesthesia. During right-hand contractions Vmean remained unchanged on the right side of the brain, whereas it increased 20 (4-37)% (P < 0.01) on the left side of the brain. Similarly, during left-hand contractions Vmean increased 24 (2-42)% (P < 0.01) on the right side of the brain, while it remained unchanged on the left side of the brain. Regional anesthesia did not quantitatively affect Vmean during right-hand contractions. In contrast, during left-hand contractions, both right and left Vmean tended to decrease. Increases in Vmean appeared despite a decrease in arterial carbon dioxide tension (P < 0.01). Heart rate and blood pressure responses to hand contractions were enhanced during regional anesthesia (P < 0.01), but left-hand contractions resulted in a less pronounced increase in blood pressure (P < 0.01). These data demonstrate a contralateral increase in cerebral perfusion during hand contractions that is dependent on intact afferent input from the working limb.

Effects of axillary blockade on regional cerebral blood flow during dynamic hand contractions

Regional cerebral blood flow (rCBF) was measured at orbitomeatal (OM) plane +5.0 and +9.0 cm in 10 subjects at rest and during dynamic hand contractions before and after axillary blockade. Handgrip strength was significantly reduced, and rating of perceived exertion increased after blockade. During hand contractions before blockade, contralateral hemispheric cerebral blood flow (CBF) at OM +9.0 increased from a resting value of 58 (49-75) to 63 (52-82) ml.100 g-1.min-1; contralateral motor sensory rCBF at OM +9 from 58 (50-77) to 71 (64-84); motor sensory rCBF at OM +5 from 67 (54-76) to 77 (64-87) and 70 (62-84) contralaterally and ipsilaterally, respectively; and supplementary motor area (SM) rCBF from 64 (53-69) to 75 (67-88) ml.100 g-1.min-1. During dynamic hand contractions after axillary blockade, CBF did not increase at OM +5 or in the SM. Furthermore, contralateral motor sensory rCBF at OM +9 increased much less. Axillary blockade had no effect on resting CBF, rCBF, or increases in the two during hand contractions of the opposite hand. Thus neural feedback from the contracting muscle is necessary for the increases in SM bilateral OM +5 motor sensory rCBF and the maximal increase in contralateral OM +9 motor sensory rCBF during dynamic hand contractions.

Acidic and basic class III chitinase mRNA accumulation in response to TMV infection of tobacco

Complementary DNA clones encoding acidic and basic isoforms of the class III chitinase were isolated from Nicotiana tabacum. The clones share ca. 65% identity, are equally homologous to the class III chitinases from cucumber and Arabidopsis, and are members of small gene families in tobacco. An acidic class III chitinase was purified from the intercellular fluid of tobacco leaves infected with tobacco mosaic virus (TMV). Partial amino acid sequencing of the protein confirmed that it was encoded by one of the cDNA clones. The mRNAs of the class III chitinases are coordinately expressed in response to TMV infection, both in infected and uninfected tissue. The acidic and basic class III chitinases constitute previously undescribed pathogenesis-related proteins in tobacco.