The Female Sexual Function Index (FSFI): a multidimensional self-report instrument for the assessment of female sexual function

This article presents the development of a brief, self-report measure of female sexual function. Initial face validity testing of questionnaire items, identified by an expert panel, was followed by a study aimed at further refining the questionnaire. It was administered to 131 normal controls and 128 age-matched subjects with female sexual arousal disorder (FSAD) at five research centers. Based on clinical interpretations of a principal components analysis, a 6-domain structure was identified, which included desire, subjective arousal, lubrication, orgasm, satisfaction, and pain. Overall test-retest reliability coefficients were high for each of the individual domains (r = 0.79 to 0.86) and a high degree of internal consistency was observed (Cronbach's alpha values of 0.82 and higher) Good construct validity was demonstrated by highly significant mean difference scores between the FSAD and control groups for each of the domains (p < or = 0.001). Additionally, divergent validity with a scale of marital satisfaction was observed. These results support the reliability and psychometric (as well as clinical) validity of the Female Sexual Function Index (FSFI) in the assessment of key dimensions of female sexual function in clinical and nonclinical samples. Our findings also suggest important gender differences in the patterning of female sexual function in comparison with similar questionnaire studies in males.

Risk of dementia and mild cognitive impairment in older people with subjective memory complaints: meta-analysis

OBJECTIVE

To investigate whether people with subjective memory complaints (SMC) but no objective deficits are at increased risk of developing mild cognitive impairment (MCI) and dementia.

METHOD

Major electronic databases were searched till 03/2014, and a meta-analysis was conducted using inception cohort studies.

RESULTS

Across 28 studies, there were 29,723 unique individuals (14,714 with SMC and 15,009 without SMC) (mean 71.6 years) followed on average for 4.8 years through to dementia. The annual conversion rate (ACR) of SMC to dementia was 2.33% (95% CI = 1.93%-2.78%) a relative risk (RR) of 2.07 (95% CI = 1.76-2.44) compared with those without SMC (n = 15,009). From 11 studies the ACR of developing MCI was 6.67% (95% CI = 4.70-8.95%). In long-term studies over 4 years, 14.1% (9.67-19.1%) of people with SMC developed dementia and 26.6% (95% CI = 5.3-39.7) went on to develop MCI. The ACR from SMC to dementia and MCI were comparable in community and non-community settings.

CONCLUSION

Older people with SMC but no objective complaints are twice as likely to develop dementia as individuals without SMC. Approximately 2.3% and 6.6% of older people with SMC will progress to dementia and MCI per year.

Plasmodium falciparum-infected erythrocytes modulate the maturation of dendritic cells

The malaria parasite Plasmodium falciparum is one of the most successful human pathogens. Specific virulence factors remain poorly defined, although the adhesion of infected erythrocytes to the venular endothelium has been associated with some of the syndromes of severe disease. Immune responses cannot prevent the development of symptomatic infections throughout life, and clinical immunity to the disease develops only slowly during childhood. An understanding of the obstacles to the development of protective immunity is crucial for developing rational approaches to prevent the disease. Here we show that intact malaria-infected erythrocytes adhere to dendritic cells, inhibit the maturation of dendritic cells and subsequently reduce their capacity to stimulate T cells. These data demonstrate both a novel mechanism by which malaria parasites induce immune dysregulation and a functional role beyond endothelial adhesion for the adhesive phenotypes expressed at the surface of infected erythrocytes.

Mouse LYVE-1 is an endocytic receptor for hyaluronan in lymphatic endothelium

The glycosaminoglycan hyaluronan is a key substrate for cell migration in tissues during inflammation, wound healing, and neoplasia. Unlike other matrix components, hyaluronan (HA) is turned over rapidly, yet most degradation occurs not locally but within distant lymph nodes, through mechanisms that are not yet understood. While it is not clear which receptors are involved in binding and uptake of hyaluronan within the lymphatics, one likely candidate is the lymphatic endothelial hyaluronan receptor LYVE-1 recently described in our laboratory (Banerji, S., Ni, J., Wang, S., Clasper, S., Su, J., Tammi, R., Jones, M., and Jackson, D.G. (1999) J. Cell Biol. 144, 789-801). Here we present evidence that LYVE-1 is involved in the uptake of hyaluronan by lymphatic endothelial cells using a new murine LYVE-1 orthologue identified from the EST data base. We show that mouse LYVE-1 both binds and internalizes hyaluronan in transfected 293T fibroblasts in vitro and demonstrate using immunoelectron microscopy that it is distributed equally among the luminal and abluminal surfaces of lymphatic vessels in vivo. In addition, we show by means of specific antisera that expression of mouse LYVE-1 remains restricted to the lymphatics in homozygous knockout mice lacking a functional gene for CD44, the closest homologue of LYVE-1 and the only other Link superfamily HA receptor known to date. Together these results suggest a role for LYVE-1 in the transport of HA from tissue to lymph and imply that further novel hyaluronan receptors must exist that can compensate for the loss of CD44 function.

Dormancy of mammary carcinoma after mastectomy

BACKGROUND

The longest interval between primary treatment of breast cancer and tumor recurrence, i.e., the limit of breast cancer dormancy, defines the appropriate length of follow-up, the effectiveness of treatment, and curability (no excess mortality risk for patients relative to the general population) for the disease. To determine this limit, we analyzed long-term follow-up data from patients who underwent a radical mastectomy during a four-decade period at the University of Chicago Hospitals.

METHODS

For 1547 patients operated on during the period from 1945 through mid-1987, the number of recurrences and deaths occurring within each postoperative year were tabulated, and the hazard rate for first recurrence or death from breast cancer was estimated by use of the actuarial method. The excess mortality rate was calculated for successive 5-year intervals, beginning at the time of mastectomy, by use of U.S. life tables and matching on the basis of age, race, and sex.

RESULTS

Most recurrences occurred within the first 10 years after mastectomy. Recurrences were rare after 20 years; only one recurrence was reported among 192 patients followed for 26-45 years. Patients who had a recurrence within 5 years following mastectomy had shorter subsequent survival times than those whose recurrence appeared after 5 years (two-sided P = .0001). The excess death rate increased with pathologic stage of the primary tumor. Overall, there was evidence of excess mortality up to 20 years postsurgery (two-sided P = .009).

CONCLUSIONS

The limit of breast cancer dormancy in this patient population appears to be between 20 and 25 years. After this time, recurrences were rare, and the mortality rate was no longer statistically significantly different from that of the general population. Patients surviving to this time without evidence of recurrence or contralateral breast cancer are probably cured.

Identification of the renal erythropoietin-producing cells using transgenic mice

Regulation of erythropoietin production by the kidneys is central to the control of erythropoiesis. Uncertainty about the identity of the renal cells involved has been a major obstacle to understanding this mechanism. We have used sequence from the mouse erythropoietin locus to direct expression of a marker gene, SV40 T antigen, to these cells in transgenic mice. The transgenic constructs contained an oligonucleotide marker (Epo-M) or SV40 sequence (Epo-TAg) in the 5' untranslated region of the mouse erythropoietin gene, flanked on each side by 9 and 7.5 kb of DNA from the mouse erythropoietin locus. Anemia-inducible expression of Epo-M and Epo-TAg was observed in the kidney. In one of thirteen lines, homologous integration of Epo-TAg into the mouse erythropoietin locus occurred. In transgenic mice bearing Epo-TAg at homologous and heterologous insertion sites, renal expression was restricted to a population of cells in the interstitium of the cortex and outer medulla. Immunohistochemical characterization by light and electron microscopy shows that these are the fibroblast-like type I interstitial cells.

Morphological evaluation of cell turnover in relation to the menstrual cycle in the "resting" human breast

This study examines cell turnover within the lobules of the "resting" human breast and correlates it to the stage of the menstrual cycle. The results are based on the morphological identification of both cell multiplication (mitosis) and cell deletion (apoptosis). It is found that these events undergo significant cyclical changes during the menstrual cycle, with raised levels towards the end of the cycle and during menses. However, in relation to a 28-day menstrual cycle, the position of the mitotic and apoptotic peaks, at Days 25 and 28 respectively, are significantly different. The high values are associated with an increase in the number of lobules showing a slight response rather than a large reaction within a few lobules. It appears that the "resting" breast tissue shows a general, rather than a focal reaction to a given hormonal environment. The possible role of oestrogen and progesterone as effectors of these changes is discussed. Our results show that the menstrual cycle influences cell turnover, though different factors may be affecting mitosis and apoptosis.

Carcinoembryonic antigens (CD66) on epithelial cells and neutrophils are receptors for Opa proteins of pathogenic neisseriae

Opa protein-expressing pathogenic neisseriae interact with CD66a-transfected COS (African green monkey kidney) and CHO (Chinese hamster ovary) cells. CD66a (BGP) is a member of carcinoembryonic antigen (CEA, CD66) family. The interactions occur at the N-terminal domain of CD66a, a region that is highly conserved between members of the CEA subgroup of the CD66 family. In this study, we have investigated the roles of CD66 expressed on human epithelial cells and polymorphonuclear phagocytes (PMNs) in adhesion mediated via Opa proteins. Using human colonic (HT29) and lung (A549) epithelial cell lines known to express CD66 molecules, we show that these receptors are used by meningococci. A monoclonal antibody, YTH71.3, against the N-terminal domain of CD66, but not 3B10 directed against domains, A1/ B1, inhibited meningococcal adhesion to host cells. When acapsulate bacteria expressing Opa proteins were used, large numbers of bacteria adhered to HT29 and A549 cells. In addition, both CD66a-transfected CHO cells and human epithelial cells were invaded by Opa-expressing meningococci, suggesting that epithelial cell invasion may occur via Opa-CD66 interactions. In previous studies we have shown that serogroup A strain C751 expresses three Opa proteins, all of which mediate non-opsonic interactions with neutrophils. We have examined the mechanisms of these interactions using antibodies and soluble chimeric receptors. The results indicate that the nature of their interactions with purified CD66a molecules and with CD66 on neutrophils is alike and that these interactions occur at the N-terminal domain of CD66. Thus, the Opa family of neisserial ligands may interact with several members of the CD66 family via their largely conserved N-terminal domains.

Evidence for the shikimate pathway in apicomplexan parasites

Parasites of the phylum Apicomplexa cause substantial morbidity, mortality and economic losses, and new medicines to treat them are needed urgently. The shikimate pathway is an attractive target for herbicides and antimicrobial agents because it is essential in algae, higher plants, bacteria and fungi, but absent from mammals. Here we present biochemical, genetic and chemotherapeutic evidence for the presence of enzymes of the shikimate pathway in apicomplexan parasites. In vitro growth of Toxoplasma gondii, Plasmodium falciparum (malaria) and Cryptosporidium parvum was inhibited by the herbicide glyphosate, a well-characterized inhibitor of the shikimate pathway enzyme 5-enolpyruvyl shikimate 3-phosphate synthase. This effect on T. gondii and P. falciparum was reversed by treatment with p-aminobenzoate, which suggests that the shikimate pathway supplies folate precursors for their growth. Glyphosate in combination with pyrimethamine limited T. gondii infection in mice. Four shikimate pathway enzymes were detected in extracts of T. gondii and glyphosate inhibited 5-enolpyruvyl shikimate 3-phosphate synthase activity. Genes encoding chorismate synthase, the final shikimate pathway enzyme, were cloned from T. gondii and P. falciparum. This discovery of a functional shikimate pathway in apicomplexan parasites provides several targets for the development of new antiparasite agents.

Cell turnover in the "resting" human breast: influence of parity, contraceptive pill, age and laterality

Morphological identification of cell multiplication (mitosis) and cell deletion (apoptosis) within the lobules of the "resting" human breast is used to assess the response of the breast parenchyma to the menstrual cycle. The responses are shown to have a biorhythm in phase with the menstrual cycle, with a 3-day separation of the mitotic and apoptotic peaks. The study fails to demonstrate significant differences in the responses between groups defined according to parity, contraceptive-pill use or presence of fibroadenoma. However, significant differences are found in the apoptotic response according to age and laterality. The results highlight the complexity of modulating influences on breast parenchymal turnover in the "resting" state, and prompt the investigation of other factors as well as steroid hormones and prolactin in the promotion of mitosis. The factors promoting apoptosis in the breast are still not clear.

Canadian Stroke Best Practice Recommendations for Acute Stroke Management: Prehospital, Emergency Department, and Acute Inpatient Stroke Care, 6th Edition, Update 2018

The 2018 update of the Canadian Stroke Best Practice Recommendations for Acute Stroke Management, 6th edition, is a comprehensive summary of current evidence-based recommendations, appropriate for use by healthcare providers and system planners caring for persons with very recent symptoms of acute stroke or transient ischemic attack. The recommendations are intended for use by a interdisciplinary team of clinicians across a wide range of settings and highlight key elements involved in prehospital and Emergency Department care, acute treatments for ischemic stroke, and acute inpatient care. The most notable changes included in this 6th edition are the renaming of the module and its integration of the formerly separate modules on prehospital and emergency care and acute inpatient stroke care. The new module, Acute Stroke Management: Prehospital, Emergency Department, and Acute Inpatient Stroke Care is now a single, comprehensive module addressing the most important aspects of acute stroke care delivery. Other notable changes include the removal of two sections related to the emergency management of intracerebral hemorrhage and subarachnoid hemorrhage. These topics are covered in a new, dedicated module, to be released later this year. The most significant recommendation updates are for neuroimaging; the extension of the time window for endovascular thrombectomy treatment out to 24 h; considerations for treating a highly selected group of people with stroke of unknown time of onset; and recommendations for dual antiplatelet therapy for a limited duration after acute minor ischemic stroke and transient ischemic attack. This module also emphasizes the need for increased public and healthcare provider’s recognition of the signs of stroke and immediate actions to take; the important expanding role of paramedics and all emergency medical services personnel; arriving at a stroke-enabled Emergency Department without delay; and launching local healthcare institution code stroke protocols. Revisions have also been made to the recommendations for the triage and assessment of risk of recurrent stroke after transient ischemic attack/minor stroke and suggested urgency levels for investigations and initiation of management strategies. The goal of this updated guideline is to optimize stroke care across Canada, by reducing practice variations and reducing the gap between current knowledge and clinical practice.

Meningococcal Opa and Opc proteins: their role in colonization and invasion of human epithelial and endothelial cells

Neisseria meningitidis (Nm) isolates from disease or during carriage express, on their outer membranes, one or more of a family of closely related proteins designated Opa proteins. In this study, we have examined the potential roles of Nm Opa proteins in bacterial attachment and invasion of endothelial as well as epithelial cells and compared the influence of Opa proteins with that of Opc protein, which has been previously shown to increase bacterial interactions with eukaryotic cells. Several variants expressing different Opa proteins (A, B, D) or Opc were selected from a culture of capsule-deficient non-piliated bacteria of strain C751. Although the Opa proteins increased bacterial attachment and invasion of endothelial cells, Opc was the most effective protein in increasing bacterial interactions with these cells. In contrast, attachment to several human epithelial cells was facilitated at least as much by OpaB as Opc protein. OpaA was largely without effect whereas OpaD conferred intermediate attachment. OpaB also increased invasion of epithelial cells; more bacteria were internalized by Chang conjunctival cells compared with Hep-2 larynx carcinoma or A549 lung carcinoma cells. Monoclonal antibody reacting with OpaB inhibited bacterial interactions with the host cells. Opa-mediated interactions were also eliminated or significantly reduced in variants expressing capsule or those with sialylated lipopolysaccharide. These data are consistent with the notion that environmental factors controlling capsule and lipopolysaccharide phenotype may modulate bacterial interactions mediated by these OM proteins. In permissive microenvironments, some Opa proteins may be important in bacterial colonization and translocation in addition to Opc. The data also support the notion that Nm Opa may confer tissue tropism.

Platelet-mediated clumping of Plasmodium falciparum-infected erythrocytes is a common adhesive phenotype and is associated with severe malaria

Sequestration of malaria-infected erythrocytes in the peripheral circulation has been associated with the virulence of Plasmodium falciparum. Defining the adhesive phenotypes of infected erythrocytes may therefore help us to understand how severe disease is caused and how to prevent or treat it. We have previously shown that malaria-infected erythrocytes may form apparent autoagglutinates of infected erythrocytes. Here we show that such autoagglutination of a laboratory line of P. falciparum is mediated by platelets and that the formation of clumps of infected erythrocytes and platelets requires expression of the platelet surface glycoprotein CD36. Platelet-dependent clumping is a distinct adhesive phenotype, expressed by some but not all CD36-binding parasite lines, and is common in field isolates of P. falciparum. Finally, we have established that platelet-mediated clumping is strongly associated with severe malaria. Precise definition of the molecular basis of this intriguing adhesive phenotype may help to elucidate the complex pathophysiology of malaria.

Effects of chronic restraint stress and estradiol on open field activity, spatial memory, and monoaminergic neurotransmitters in ovariectomized rats

Twenty-one days of chronic restraint stress impairs male rat performance on the radial arm maze [Luine et al. (1994) Brain Res. 639, 167-170], but enhances female rat performance [Bowman et al. (2001) Brain Res. 904, 279-289]. To assess possible ovarian hormone mechanisms underlying this sexually dimorphic response to stress, we examined chronic stress effects in ovariectomized rats. Ovariectomized rats received Silastic capsule implants containing cholesterol or estradiol and were assigned to a daily restraint stress (21 days, 6 h/day) or non-stress group. Following the stress period, subjects were tested for open field activity and radial arm maze performance. Stress and estradiol treatment affected open field activity. All stressed animals, with or without estradiol treatment, made fewer total outer sector crossings. In contrast, estradiol-treated animals, with or without stress, made more inner sector visits, an indication that estradiol decreased anxious behavior on the open field across time. As measured by the total number of visits required to complete the task, stress did not affect radial arm maze performance in ovariectomized rats, but estradiol-treated animals, with or without stress, performed better than non-treated animals on the radial arm maze. Stressed subjects receiving estradiol showed the best radial arm maze performance. Following killing, tissue samples were obtained from various brain regions known to contribute to learning and memory, and monoamine and metabolite levels were measured. Several changes were observed in response to both stress and estradiol. Most noteworthy, stress treatment decreased homovanillic acid levels in the prefrontal cortex, an effect not previously observed in stressed intact females. Estradiol treatment increased norepinephrine levels in CA3 region of the hippocampus, mitigating stress-dependent changes. Both stress and estradiol decreased dentate gyrus levels of 5-hydroxyindole acetic acid. In summary, the current study provides novel information showing that estradiol alters behavioral and neurochemical responses to stress in ovariectomized rats. Estradiol treatment decreased anxious behavior on the open field and stressed animals receiving estradiol had enhanced radial arm maze performance. In relation to interactions between stress and estradiol on cognition and anxiety, changes in the prefrontal cortex dopaminergic system, dentate gyrus serotonergic system, and norepinephrine levels in the CA3 region appear important. Results show that estradiol may moderate stress effects on cognition and anxiety through both organizational and activation effects.

An ultrastructural study of the early development and tissue cyst formation of Toxoplasma gondii in the brains of mice

The ultrastructural features of the early development and tissue cyst formation of Toxoplasma gondii were examined in the brains of mice at various intervals from 7 days to 22 months post inoculation (PI). At 11 days PI toxoplasmas, with the ultrastructural features of the proliferative (endozoite) form, were identified undergoing multiplication within both inflammatory and neural cells. Early tissue cyst formation was also observed, predominantly within neurons. By 21 days PI the proliferative forms had disappeared and only developing tissue cysts containing densely packed cystozoites were present. The proportion of dividing cystozoites decreased with increasing size and age of the cysts. The wall of the tissue cyst developed as an adaptation of the lining of the parasitophorous vacuole. In the majority of older cysts, numerous tubular structures were present beneath the cyst wall. All the cysts observed were retained within intact host cells. The only morphological change with increasing age was that a proportion of the older cysts contained loosely packed cystozoites in an electron lucent ground substance. There was no evidence of any degenerative changes within the cystozoites.

Surface antigens of Toxoplasma gondii: variations on a theme

Toxoplasma gondii is an obligate intracellular protozoan parasite with an exceptionally broad host range. Recently, it has become apparent that the number of surface antigens (SAGs) it expresses may rival the number of genera it can infect. Most of these antigens belong to the developmentally regulated and distantly related SAG1 or SAG2 families. The genes encoding the surface antigens are distributed throughout the T. gondii genome, with remarkably little polymorphism observed at each locus. Results from a number of studies have suggested that the surface antigens play an important role in the biology of the parasite. For example, SAG3 null mutants generated by targeted disruption provide convincing evidence that this surface antigen, at least, functions during parasite attachment. Analyses of a SAG1 knockout in rodents, however, indicate that this surface antigen may play a crucial role in immune modulation or virulence attenuation. The current understanding of the SAG1 and SAG2 families will be discussed here.

The role of pili in the interactions of pathogenic Neisseria with cultured human endothelial cells

The influence of the two surface structures of Neisseria meningitidis, capsule and pili, in bacterial interactions with human endothelial cells was investigated. Increased association correlated with the presence of pili on bacteria while capsule type had no apparent effect. Strains expressing both Class I and Class II pili associated with endothelial cells in significantly larger numbers compared with the non-piliated variants of the same strains (greater than 10x). Variants of Neisseria gonorrhoeae strain P9 expressing antigenically distinct pili also associated with endothelial cells in larger numbers (greater than 30x) compared with the non-piliated variant. Electron microscopic studies confirmed these data and showed that gonococci were internalized more frequently compared with meningococci. One consequence of increased association was an increase in the cytopathic effect of bacteria on the target cells.

The chromatin-associated protein H-NS alters DNA topology in vitro

H-NS is one of the two most abundant proteins in the bacterial nucleoid and influences the expression of a number of genes. We have studied the interaction of H-NS with DNA; purified H-NS was demonstrated to constrain negative DNA supercoils in vitro. This provides support for the hypothesis that H-NS influences transcription via changes in DNA topology, and is evidence of a structural role for H-NS in bacterial chromatin. The effects of H-NS on topology were only observed at sub-saturating concentrations of the protein. In addition, a preferred binding site on DNA was identified by DNase I footprinting at sub-saturating H-NS concentrations. This site corresponded to a curved sequence element which we previously showed, by in vivo studies, to be a site at which H-NS influences transcription of the proU operon. When present in saturating concentrations, H-NS did not constrain supercoils and bound to DNA in a sequence-independent fashion, covering all DNA molecules from end to end, suggesting that H-NS may form distinct complexes with DNA at different H-NS:DNA ratios. The data presented here provide direct support for the hypothesis that H-NS acts at specific sites to influence DNA topology and, hence, transcription.

Defective embryonic neurogenesis in Ku-deficient but not DNA-dependent protein kinase catalytic subunit-deficient mice

Mammalian nonhomologous DNA end joining employs Ku70, Ku80, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), XRCC4, and DNA ligase IV (Lig4). Herein, we show that Ku70 and Ku80 deficiency but not DNA-PKcs deficiency results in dramatically increased death of developing embryonic neurons in mice. The Ku-deficient phenotype is qualitatively similar to, but less severe than, that associated with XRCC4 and Lig4 deficiency. The lack of a neuronal death phenotype in DNA-PKcs-deficient embryos and the milder phenotype of Ku-deficient versus XRCC4- or Lig4-deficient embryos correlate with relative leakiness of residual end joining in these mutant backgrounds as assayed by a V(D)J recombination end joining assay. We conclude that normal development of the nervous system depends on the four evolutionarily conserved nonhomologous DNA end joining factors.

Cloning and characterization of a bradyzoite-specifically expressed gene (hsp30/bag1) of Toxoplasma gondii, related to genes encoding small heat-shock proteins of plants

Stage conversion between the tachyzoite and bradyzoite forms of the protozoan parasite Toxoplasma gondii is an important aspect in the pathogenesis of toxoplasmosis. In an initial investigation of molecular regulation of stage conversion in T. gondii, we describe the cloning and characterization of a bradyzoite-specifically expressed gene (hsp30/bag1). Bradyzoite formation was induced in cell culture by alkaline pH, and this was followed by purification of this parasitic stage using magnetic cell sorting. A bradyzoite cDNA library was constructed by random amplification using the polymerase chain reaction. Screening with a bradyzoite-specific monoclonal antibody identified a reactive clone. The amino acid sequence derived from the 687 bp open reading frame showed similarity to the conserved C-terminal region of small heat-shock proteins from plants. Stage-specific expression of the naturally occurring 30 kDa antigen in bradyzoites was confirmed by polyclonal antisera generated against the recombinant antigen. Immunoelectron microscopy indicated a cytosolic location of this antigen in bradyzoites. The expression of HSP30/BAG1 seems to be regulated at the mRNA level, since reverse polymerase chain reaction using bradyzoite-specific primers amplified transcripts in bradyzoites only, not in tachyzoites.

Opc- and pilus-dependent interactions of meningococci with human endothelial cells: molecular mechanisms and modulation by surface polysaccharides

The interplay between four surface-expressed virulence factors of Neisseria meningitidis (pili, Opc, capsule and lipopolysaccharide (LPS)) in host cell adhesion and invasion was examined using derivatives of a serogroup B strain, MC58, created by mutation (capsule, Opc) and selection of variants. To examine the role of Opc and of additional expression of pili, bacteria lacking the expression of Opa proteins were used. The effects of different LPS structures were examined in variants expressing either sialylated (L3 immunotype) or truncated non-sialylated (L8 immunotype) LPS. Studies showed that (i) pili were essential for meningococcal interactions with host cells in both capsulate and acapsulate bacteria with the sialylated L3 LPS immunotype, (ii) the Opc-mediated invasion of host cells by piliated and non-piliated bacteria was observed only in acapsulate organisms with L8 LPS immunotype, and (iii) expression of pili in Opc-expressing bacteria resulted in increased invasion. Investigations on the mechanisms of cellular invasion indicated that the Opc-mediated invasion was dependent on the presence of serum in the incubation medium and was mediated by serum proteins with arginine-glycine-aspartic acid (RGD) sequence. Cellular invasion in piliated Opc+ phenotype also required bridging molecules containing the RGD recognition sequence and appeared to involve the integrin alpha v beta 3 as a target receptor on endothelial cells. These studies extend the previous observations on variants of a serogroup A strain (C751) and show that Opc mediates cellular invasion in distinct meningococcal strains and provide confirmation of its mechanism of action. This is the first investigation that evaluates, using derivatives of a single strain, the interplay between four meningococcal surface virulence factors in host cell invasion.

Pilus-facilitated adherence of Neisseria meningitidis to human epithelial and endothelial cells: modulation of adherence phenotype occurs concurrently with changes in primary amino acid sequence and the glycosylation status of pilin

Adherence of capsulate Neisseria meningitidis to endothelial and epithelial cells is facilitated in variants that express pili. Whereas piliated variants of N. meningitidis strain C311 adhered to endothelial cells in large numbers (> 150 bacteria/cell), derivatives containing specific mutations that disrupt pilE encoding the pilin subunit were both non-piliated and failed to adhere to endothelial cells (< 1 bacterium/cell). In addition, meningococcal pili recognized human endothelial and epithelial cells but not cells originating from other animals. Variants of strain C311 were obtained that expressed pilins of reduced apparent M(r) and exhibited a marked increase in adherence to epithelial cells. Structural analysis of pilins from two hyper-adherent variants and the parent strain were carried out by DNA sequencing of their pilE genes. Deduced molecular weights of pilins were considerably lower compared with their apparent M(r) values on SDS-PAGE. Hyper-adherent pilins shared unique changes in sequence including substitution of Asn-113 for Asp-113 and changes from Asn-Asp-Thr-Asp to Thr-Asp-Ala-Lys at residues 127-130 in mature pilin. Asn residues 113 and 127 of 'parental' pilin both form part of the typical eukaryotic N-glycosylation motif Asn-X-Ser/Thr and could potentially be glycosylated post-translationally. The presence of carbohydrate on pilin was demonstrated and when pilins were deglycosylated, their migration on SDS-PAGE increased, supporting the notion that variable glycosylation accounts for discrepancies in apparent and deduced molecular weights. Functionally distinct pilins produced by two fully piliated variants of a second strain (MC58) differed only in that the putative glycosylation motif Asn-60-Asn-61-Thr-62 in an adherent variant was replaced with Asp-60-Asn-61-Ser-62 in a non-adherent variant. Fully adherent backswitchers obtained from the non-adherent variant always regained Asn-60 but retained Ser-62. We propose, therefore, that functional variations in N. meningitidis pili may be modulated in large part by primary amino acid sequence changes that ablate or create N-linked glycosylation sites on the pilin subunit.

Intraleucocytic malaria pigment and prognosis in severe malaria

The quantity of malaria pigment liberated into the circulation at schizogony reflects the pathogenic sequestered parasite burden in Plasmodium falciparum malaria, and may therefore be a measure of disease severity. Among 300 consecutive adult patients with severe falciparum malaria, the 40 who died had significantly higher proportions of malaria pigment-containing neutrophils on admission (mean = 7.7%, standard deviation (SD) = 5.9%) and pigment-containing monocytes (mean = 8.6%, SD = 5.9%) than did survivors (mean 3.2%, SD = 4.1% and mean 4.8%, SD = 4.6%, respectively) (P < 0.0001). This proved a better indicator of prognosis than the peripheral parasite count. A count of peripheral neutrophils containing visible pigment > or = 5% predicted a fatal outcome with 73% sensitivity and 77% specificity (relative risk 6.2, 95% confidence interval (CI) 3.2-11.8) compared to 60% sensitivity and 57% specificity for parasitaemia > 100,000/microL (relative risk 1.8, 95% CI 1.0-3.3). The peripheral blood count of pigment-containing neutrophils in severe malaria is a rapid, simple, and practical prognostic test.

Natural history of node-negative breast cancer: a study of 826 patients with long-term follow-up

PURPOSE

We were interested in examining the long-term outcome of patients with node-negative breast cancer to address the following questions: (1) Is node-negative breast cancer a disease that is curable by local modalities? (2) Are there predictors of disseminated disease in node-negative breast cancer? (3) Are there subgroups of tumors that have different times to recurrence?

METHODS

From 1927 to 1984, 826 women with node-negative breast cancer were treated at the University of Chicago. Patients underwent either a radical or extended radical mastectomy (83%) or a modified radical mastectomy (13%).

RESULTS

Follow-up evaluation ranged from 9 to 523 months (43.6 years); the mean follow-up period of survivors is 162 months (13.5 years). On multivariate analysis, the strongest predictor of outcome and time to relapse was pathologic tumor size. Patients with tumors less than 2 cm had a 20-year disease-free survival (DFS) rate of 79% and a median time to recurrence of 48 months as compared with patients with tumors greater than 2 cm, who had a survival rate of 64% (P < .001) and a median time to recurrence of 37 months (P = .01).

CONCLUSION

With extended follow-up evaluation, node-negative breast cancer is a curable disease. Size is the strongest predictor of dissemination and rate of relapse. These data suggest that given the natural history of node-negative breast cancer, analysis of clinical trials with short follow-up periods can be misleading, since it may identify those patients whose tumors have a greater virulence but not necessarily a greater likelihood to metastasize.