Diagnostic challenges and prognostic implications of extranodal extension in head and neck cancer: a state of the art review and gap analysis

Extranodal extension (ENE) is a pattern of cancer growth from within the lymph node (LN) outward into perinodal tissues, critically defined by disruption and penetration of the tumor through the entire thickness of the LN capsule. The presence of ENE is often associated with an aggressive cancer phenotype in various malignancies including head and neck squamous cell carcinoma (HNSCC). In HNSCC, ENE is associated with increased risk of distant metastasis and lower rates of locoregional control. ENE detected on histopathology (pathologic ENE; pENE) is now incorporated as a risk-stratification factor in human papillomavirus (HPV)-negative HNSCC in the eighth edition of the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control (UICC) TNM classification. Although ENE was first described almost a century ago, several issues remain unresolved, including lack of consensus on definitions, terminology, and widely accepted assessment criteria and grading systems for both pENE and ENE detected on radiological imaging (imaging-detected ENE; iENE). Moreover, there is conflicting data on the prognostic significance of iENE and pENE, particularly in the context of HPV-associated HNSCC. Herein, we review the existing literature on ENE in HNSCC, highlighting areas of controversy and identifying critical gaps requiring concerted research efforts.

Pathologic complete response following low-dose radiation for advanced oral cavity cancer in a patient with human immunodeficiency virus

BACKGROUND

Advanced squamous cell carcinoma (SCCa) of the oral cavity is often not amenable to curative-intent therapy due to tumor location, tumor size, or comorbidities.

CASE PRESENTATION

A 51-year-old male patient with human immunodeficiency virus and on highly active antiretroviral therapy (HAART) presented with a cT4aN2c SCCa of the tongue. He received a preoperative single course of Quad-Shot radiation therapy to 14 Gy in 4 fractions followed by surgical resection. Patient had no residual carcinoma on surgical pathology and no evidence of disease on subsequent clinical and radiological exams.

CONCLUSIONS

To our knowledge, this is the first case of pathologic complete response for a patient on HAART following a single cycle of the Quad-Shot regimen for advanced oral cavity SCCa. Protease inhibitors in HAART can induce spontaneous tumor regression via inhibition of proteasome function and activation of apoptosis, and thus act as a cancer therapeutic.

A bacterial vaccine polypeptide protective against nontypable Haemophilus influenzae

Nontypeable strains of Haemophilus influenzae (NTHi) are one of the most common cause of otitis media and the most frequent infection associated with exacerbations of chronic obstructive pulmonary disease; there is currently no vaccine in the U.S. to prevent NTHi. Using bioinformatics and structural vaccinology, we previously identified several NTHi species-conserved and sequence-conserved peptides that mediate passive protection in the rat model of infection. Using these, and similar peptides, we designed Hi Poly 1, a Bacterial Vaccine Polypeptide, comprising 9 unique peptides from 6 different surface proteins. Recombinant Hi Poly 1 was purified by affinity chromatography. Forty chinchillas were immunized three times with 200 µg of Hi Poly 1 with alum adjuvant; similarly, 41 controls were immunized with adjuvant alone. The average Log₂ IgG titer among immunized animals was 17.04, and IgG antibodies against each component peptide were detected. In the infant rat model, antisera from immunized chinchillas provided significant passive protection compared to PBS (p = 0.01) and pre-immune sera (p = 0.03). In the established chinchilla model of NTHi otitis media, the vaccinated group cleared infection faster than the control group as indicated by significantly decreased positive findings on video-otoscopy (p < 0.0001) and tympanometry (p = 0.0002) on day 7, and for middle ear fluid obtained by aspiration (p = 0.0001) on day 10 post-infection. Using 12 representative NTHi strains in a Live-Cell ELISA, greater antibody binding to each strain was detected with post Hi Poly 1 than the pre-immune chinchilla antisera. The data from this proof-of-principle study demonstrate the effectiveness of Hi Poly 1 against the NTHi in two relevant preclinical models of bacteremia and otitis media as well as surface antibody binding across the species. The Bacterial Vaccine Polypeptide approach to a vaccine against NTHi also serves as a paradigm for development of similar vaccines to protect against other bacteria.

2019 Chitranjan S. Ranawat Award: Elective joint arthroplasty outcomes improve in malnourished patients with nutritional intervention: a prospective population analysis demonstrates a modifiable risk factor

AIMS

To date, no study has demonstrated an improvement in postoperative outcomes following elective joint arthroplasty with a focus on nutritional intervention for patients with preoperative hypoalbuminaemia. In this prospective study, we evaluated differences in the hospital length of stay (LOS), rate of re-admission, and total patient charges for a malnourished patient study population who received a specific nutrition protocol before surgery.

PATIENTS AND METHODS

An analytical report was extracted from the electronic medical record (EMR; Epic, Verona, Wisconsin) of a five-hospital network joint arthroplasty patient data set between 2014 and 2017. A total of 4733 patients underwent joint arthroplasty and had preoperative measurement of albumin levels: 2220 at four hospitals and 2513 at the study hospital. Albumin ≤ 3.4 g/l, designated as malnutrition, was found in 543 patients (11.5%). A nutritional intervention programme focusing on a high-protein, anti-inflammatory diet was initiated in January 2017 at one study hospital. Hospital LOS, re-admission rate, and 90-day charges were compared for differential change between patients in study and control hospitals for all elective hip and knee arthroplasty patients, and for malnourished patients over time as the nutrition intervention was implemented.

RESULTS

Malnourished patients with nutritional intervention at the study hospital had shorter hospital LOS beginning in 2017 than malnourished patients at control hospitals during the same period (p = 0.04). Similarly, this cohort had significantly lower primary hospitalization charges, charges associated with hospital re-admissions, and 90-day total charges (p < 0.001). Inclusion of covariant potential confounders (age, anaemia, diabetes, and obesity) did not alter the conclusions of the primary statistical analysis.

CONCLUSION

Joint arthroplasty outcomes were positively affected in study patients with low albumin when a high-protein, anti-inflammatory diet was encouraged. Elective surgery was neither cancelled nor delayed with a malnutrition designation. While the entire network population experienced improved postoperative outcomes, malnourished control patients did not experience this improvement. This study demonstrated that education on malnutrition can benefit patients. Cite this article: Bone Joint J 2019;101-B(7 Supple C):17-21.

Antisera Against Certain Conserved Surface-Exposed Peptides of Nontypeable Haemophilus influenzae Are Protective

Nontypeable Haemophilus influenzae (NTHi) cause significant disease, including otitis media in children, exacerbations of chronic obstructive pulmonary disease, and invasive disease in susceptible populations. No vaccine is currently available to prevent NTHi disease. The interactions of NTHi and the human host are primarily mediated by lipooligosaccharide and a complex array of surface-exposed proteins (SEPs) that act as receptors, sensors and secretion systems. We hypothesized that certain SEPs are present in all NTHi strains and that a subset of these may be antibody accessible and represent protective epitopes. Initially we used 15 genomic sequences available in the GenBank database along with an additional 11 genomic sequences generated by ourselves to identify the core set of putative SEPs present in all strains. Using bioinformatics, 56 core SEPs were identified. Molecular modeling generated putative structures of the SEPs from which potential surface exposed regions were defined. Synthetic peptides corresponding to ten of these highly conserved surface-exposed regions were used to raise antisera in rats. These antisera were used to assess passive protection in the infant rat model of invasive NTHi infection. Five of the antisera were protective, thus demonstrating their in vivo antibody accessibility. These five peptide regions represent potential targets for peptide vaccine candidates to protect against NTHi infection.

Acculturation and functional impairment among older Chinese and Vietnamese in San Diego County, California

Level of acculturation and the relationship to functional impairment was examined among a group of Chinese (n = 50) and Vietnamese (n = 50) 45 years and older in San Diego County, California. Prevalence of functional impairment and level of acculturation, one-way analysis of variance and Pearson correlations were utilized to examine differences between ethnicity, gender and age groups, as well as significant relationships between various dimensions of impairment and levels of acculturation. Findings indicated that lack of English language skills and lack of use and exposure to English were associated with social and economic resource impairment, mental and physical health impairment, and ADL impairment, as measured by a modified OARS instrument. Data suggested that the visibility and extensiveness of the Vietnamese community may serve to buffer the negative effects associated with the acculturation process for the Vietnamese.

Comparison of transcription of the Haemophilus influenzae iron/heme modulon genes in vitro and in vivo in the chinchilla middle ear

Background

Haemophilus influenzae is a significant cause of childhood otitis media, and also has an absolute growth requirement for heme. Recent microarray studies using three H. influenzae isolates were used to propose a putative core of genes responsive to iron and heme levels. Included in the core modulon were thirty seven genes that are preferentially expressed under iron/heme limitation, most of which are directly involved with iron and or heme acquisition. In this report, the core iron/heme modulon was further refined following microarray analysis of two additional nontypeable H. influenzae isolates from patients with otitis media. The transcriptional status of the genes comprising the refined iron/heme core modulon was then assessed in vivo, in a chinchilla model of otitis media. These in vivo experiments were performed to address the hypothesis that iron and heme regulated genes are both highly expressed in vivo and important, during clinical infection.

Results

Microarray analysis of two additional H. influenzae strains resulted in the definition of a core of iron/heme responsive genes. This core consisted of 35 genes maximally expressed under heme restriction and a further 20 genes maximally expressed in heme replete conditions. In vivo studies were performed with two nontypeable H. influenzae strains, 86-028NP and HI1722. The majority of operons identified as members of the core modulon by microarray were also actively upregulated in the chinchilla ear during otitis media. In 86-028NP, 70% of the operons were significantly upregulated while in HI1722 100% of the operons were upregulated in samples recovered from the chinchilla middle ear.

Conclusion

This study elucidates a conserved core of H. influenzae genes the transcription of which is altered by the availability of iron and heme in the growth environment, and further assesses transcription of these genes in vivo. Elucidation of this modulon allows for identification of genes with unrecognized roles in iron/heme acquisition or homeostasis and/or potential roles in virulence. Defining these core genes is also of potential importance in identifying targets for therapeutic and vaccine designs since products of these genes are likely to be preferentially expressed during growth in iron/heme restricted sites of the human body.

The role of the RNA chaperone Hfq in Haemophilus influenzae pathogenesis

Background

The RNA binding protein Hfq of Haemophilus influenzae is highly homologous to Hfq from other bacterial species. In many of these other bacteria, Hfq affects the expression of a broad range of genes and enhances the ability to respond to stressful environments. However, the role of Hfq in H. influenzae is unknown.

Results

Deletion mutants of hfq were generated in the nontypeable H. influenzae strains R2866 and 86-028NP to assess the role of Hfq in these well characterized but genotypically and phenotypically divergent clinical isolates. A deletion mutation of hfq had no effect on growth of H. influenzae in nutrient rich media and had no effect on survival in several stressful conditions in vitro. However, the mutation resulted in a reduced ability to utilize heme from hemoglobin. The mutant and wild type strains were assessed for virulence and competitive fitness in models of invasive disease and otitis media. In the chinchilla model of otitis media, the hfq mutant of 86-028NP exhibited impaired competitive fitness when compared to its wild type progenitor but exhibited no apparent defect in virulence. In the infant rat model, deletion of hfq in R2866 resulted in reduced bacterial titers in blood and a shorter duration of infection when compared to the wild type strain in the competitive fitness study.

Conclusion

We conclude that Hfq is involved in the utilization of essential nutrients and facilitates infection by H. influenzae.

Signature-tagging of a bacterial isolate demonstrates phenotypic variability of the progeny in vivo in the absence of defined mutations

Awareness of the high degree of redundancy that occurs in several nutrient uptake pathways of Haemophilus influenzae led us to attempt to develop a quantitative STM method that could identify both null mutants and mutants with decreased fitness that remain viable in vivo. To accomplish this task we designed a modified STM approach that utilized a set of signature tagged wild-type (STWT) strains (in a single genetic background) as carriers for mutations in genes of interest located elsewhere in the genome. Each STWT strain differed from the others by insertion of a unique, Q-PCR-detectable, seven base pair tag into the same redundant gene locus. Initially ten STWTs were created and characterized in vitro and in vivo. As anticipated, the STWT strains were not significantly different in their in vitro growth. However, in the chinchilla model of otitis media, certain STWTs outgrew others by several orders of magnitude in mixed infections. Removal of the predominant STWT resulted in its replacement by a different predominant STWT on retesting. Unexpectedly we observed that the STWT exhibiting the greatest proliferation was animal dependent. These findings identify an inherent inability of the signature tag methodologies to accurately elucidate fitness in this animal model of infection and underscore the subtleties of H. influenzae gene regulation.

A functional tonB gene is required for both virulence and competitive fitness in a chinchilla model of Haemophilus influenzae otitis media

Background

Haemophilus influenzae requires heme for aerobic growth and possesses multiple mechanisms to obtain this essential nutrient.

Methods

An insertional mutation in tonB was constructed and the impact of the mutation on virulence and fitness in a chinchilla model of otitis media was determined. The tonB insertion mutant strain was significantly impacted in both virulence and fitness as compared to the wildtype strain in this model.

Conclusions

The tonB gene of H. influenzae is required for the establishment and maintenance of middle ear infection in this chinchilla model of bacterial disease.

Identification of a siderophore utilization locus in nontypeable Haemophilus influenzae

BACKGROUND

Haemophilus influenzae has an absolute aerobic growth requirement for either heme, or iron in the presence of protoporphyrin IX. Both iron and heme in the mammalian host are strictly limited in their availability to invading microorganisms. Many bacterial species overcome iron limitation in their environment by the synthesis and secretion of small iron binding molecules termed siderophores, which bind iron and deliver it into the bacterial cell via specific siderophore receptor proteins on the bacterial cell surface. There are currently no reports of siderophore production or utilization by H. influenzae.

RESULTS

Comparative genomics revealed a putative four gene operon in the recently sequenced nontypeable H. influenzae strain R2846 that encodes predicted proteins exhibiting significant identity at the amino acid level to proteins involved in the utilization of the siderophore ferrichrome in other bacterial species. No siderophore biosynthesis genes were identified in the R2846 genome. Both comparative genomics and a PCR based analysis identified several additional H. influenzae strains possessing this operon. In growth curve assays strains containing the genes were able to utilize ferrichrome as an iron source. H. influenzae strains lacking the operon were unable to obtain iron from ferrichrome. An insertional mutation in one gene of the operon abrogated the ability of strains to utilize ferrichrome. In addition transcription of genes in the identified operon were repressible by high iron/heme levels in the growth media.

CONCLUSIONS

We have identified an iron/heme-repressible siderophore utilization locus present in several nontypeable H. influenzae strains. The same strains do not possess genes encoding proteins associated with siderophore synthesis. The siderophore utilization locus may enable the utilization of siderophores produced by other microorganisms in the polymicrobial environmental niche of the human nasopharynx colonized by H. influenzae. This is the first report of siderophore utilization by H. influenzae.

Characterization of the Haemophilus influenzae tehB gene and its role in virulence

The Haemophilus influenzae ORF designated HI1275 in the Rd KW20 genomic sequence encodes a putative S-adenosyl methyltransferase with significant similarity to tellurite-resistance determinants (tehB) in other species. While the H. influenzae tehB can complement an Escherichia coli tehB mutation, thus restoring tellurite resistance, its role in H. influenzae is unknown. In a previous study defining the iron and haem modulon of H. influenzae, we showed that transcription of this gene in H. influenzae Rd KW20 increases during growth in iron- and haem-restricted media. Since iron and haem uptake genes, and other known virulence factors, constitute the majority of the iron- and haem-regulated gene set, we postulated that tehB may play a role in nutrient acquisition and/or the virulence of H. influenzae. A tehB mutant was constructed in the H. influenzae type b strain 10810 and was evaluated for growth defects in various supplemented media, as well as for its ability to cause infection in rat models of infection. Deletion of tehB leads to an increase in sensitivity both to tellurite and to the oxidizing agents cumene hydroperoxide, tert-butyl hydroperoxide and hydrogen peroxide. The tehB mutant additionally showed a significantly reduced ability to utilize free haem as well as several haem-containing moieties including haem-human serum albumin, haemoglobin and haemoglobin-haptoglobin. Examination of the regulation kinetics indicated that transcription of tehB was independent of both tellurite exposure and oxidative stress. Paired comparisons of the tehB mutant and the wild-type H. influenzae strain 10810 showed that tehB is required for wild-type levels of infection in rat models of H. influenzae invasive disease. To our knowledge this is the first report of a role for tehB in virulence in any bacterial species. These data demonstrate that H. influenzae tehB plays a role in both resistance to oxidative damage and haem uptake/utilization, protects H. influenzae from tellurite exposure, and is important for virulence of this organism in an animal model of invasive disease.

The heme-binding protein (HbpA) of Haemophilus influenzae as a virulence determinant

Haemophilus influenzae has an absolute growth requirement for heme and the heme-binding lipoprotein (HbpA) and has been implicated in the utilization of this essential nutrient. We constructed an insertional mutation of hbpA in a type b and a nontypeable H. influenzae strain. In the type b strain, the hbpA mutant was impaired in utilization of heme complexed to either hemopexin or to albumin and in the utilization of low levels of heme but not in the utilization of heme at high levels or of hemoglobin or hemoglobin-haptoglobin complexes. In contrast, the hbpA mutant derivative of the nontypeable strain was impaired in utilization of all tested heme sources. We further examined the impact of the hbpA mutation in animal models of H. influenzae disease. The hbpA mutant of the nontypeable strain was indistinguishable from the wild-type strain in the chinchilla model of otitis media. The hbpA mutant derivative of the type b strain caused bacteremia as well as the wild-type strain in 5-day old infant rats. However, in 30-day old rats the hbpA caused significantly lower rates of bacteremia than the wild-type strain indicating a role for hbpA and heme acquisition in virulence in this model of H. influenzae disease. In conclusion, HbpA is important for heme utilization by multiple H. influenzae strains and is a virulence determinant in a model of H. influenzae invasive disease.

The dppBCDF gene cluster of Haemophilus influenzae: Role in heme utilization

BACKGROUND

Haemophilus influenzae requires a porphyrin source for aerobic growth and possesses multiple mechanisms to obtain this essential nutrient. This porphyrin requirement may be satisfied by either heme alone, or protoporphyrin IX in the presence of an iron source. One protein involved in heme acquisition by H. influenzae is the periplasmic heme binding protein HbpA. HbpA exhibits significant homology to the dipeptide and heme binding protein DppA of Escherichia coli. DppA is a component of the DppABCDF peptide-heme permease of E. coli. H. influenzae homologs of dppBCDF are located in the genome at a point distant from hbpA. The object of this study was to investigate the potential role of the H. influenzae dppBCDF locus in heme utilization.

FINDINGS

An insertional mutation in dppC was constructed and the impact of the mutation on the utilization of both free heme and various proteinaceous heme sources as well as utilization of protoporphyrin IX was determined in growth curve studies. The dppC insertion mutant strain was significantly impacted in utilization of all tested heme sources and protoporphyin IX. Complementation of the dppC mutation with an intact dppCBDF gene cluster in trans corrected the growth defects seen in the dppC mutant strain.

CONCLUSION

The dppCBDF gene cluster constitutes part of the periplasmic heme-acquisition systems of H. influenzae.

The adoption of smoke-free hospital campuses in the United States

BACKGROUND

The adoption of a smoke-free hospital campus policy is often a highly publicised local event. National media coverage suggests that the trend towards adopting these policies is growing, and this publicity can frequently lead hospital administrators to consider the adoption of such policies within their own institutions. Little is actually known, however, about the prevalence of these policies or their impact.

OBJECTIVES

To determine the national prevalence of smoke-free hospital campus policies and the relation between these policies and performance on nationally standardised measures for smoking cessation counselling in US hospitals.

METHODS

4494 Joint Commission-accredited hospitals were invited to complete a web-based questionnaire assessing current smoking policies and future plans. Smoking cessation counselling rates were assessed through nationally standardised measures.

RESULTS

The 1916 hospitals responding to the survey (43%) were statistically similar to non-responders with respect to performance measure rates, smoking policies and demographic characteristics. Approximately 45% of responders reported an existing smoke-free hospital campus policy. With respect to demographics, higher proportions of smoke-free campus policies were reported in non-teaching and non-profit hospitals. Smoke-free campus hospitals were also more likely to provide smoking cessation counselling to patients with acute myocardial infarction, heart failure and pneumonia who smoke (p<0.001).

CONCLUSIONS

By February 2008, 45% of US hospitals (up from approximately 3% in 1992) had adopted a smoke-free campus policy; another 15% reported actively pursuing the adoption of such a policy. By the end of 2009, it is likely that the majority of US hospitals will have a smoke-free campus.

The iron/heme regulated genes of Haemophilus influenzae: comparative transcriptional profiling as a tool to define the species core modulon

BACKGROUND

Haemophilus influenzae requires heme for aerobic growth and possesses multiple mechanisms to obtain this essential nutrient. Although an understanding of the heme acquisition mechanisms of H. influenzae is emerging, significant gaps in our knowledge remain. Unresolved issues include the identities of all genes exhibiting altered transcription in response to iron and heme availability, the fraction of such genes functioning in iron/heme acquisition, and the heterogeneity of this gene set among clinical isolates. Previously we utilized H. influenzae strain Rd KW20 to demonstrate the utility of transcriptional profiling in defining the genes exhibiting altered transcription in response to environmental iron and heme levels. The current study expands upon those observations by determining the iron/heme modulons of two clinical isolates, the type b isolate 10810 and the nontypeable isolate R2866. These data are used to begin to define the core iron/heme modulon of the species.

RESULTS

Microarray studies were performed to compare gene expression on transition from iron/heme-restricted to iron/heme-replete conditions for each isolate. Of 1820 ORFs on the array corresponding to R2866 genes, 363 were significantly differentially expressed: 233 were maximally transcribed under iron/heme-replete conditions and 130 under iron/heme-restricted conditions. Of the 1883 ORFs representing genes of strain 10810, 353 were significantly differentially transcribed: 150 were preferentially transcribed under iron/heme-replete conditions and 203 under iron/heme-restricted conditions. Comparison of the data sets indicated that 163 genes exhibited similar regulation in both isolates and that 74 of these exhibited similar patterns of regulation in Rd KW20. These comprise the putative core iron/heme modulon.

CONCLUSION

This study provides evidence for a conserved core of H. influenzae genes the transcription of which is altered by the availability of iron and/or heme in the growth environment. Elucidation of this modulon provides a means to identify genes with unrecognized roles in iron/heme acquisition or homeostasis, unanticipated responsiveness to environmental levels of the micronutrients or potential roles in virulence. Defining these core genes is also of potential importance in identifying targets for therapeutic and vaccine designs since products of these genes are likely to be preferentially expressed during growth in iron/heme restricted sites of the human body.

Hip axis length variation: its correlation with anthropometric measurements in women from three ethnic groups

We compared hip axis length (HAL) in 157 non-Hispanic white women, 292 African-American women, and 210 Mexican-American women. After adjusting for maximal hip girth, there were no residual differences in HAL by ethnicity. Differences in hip fracture risk seen between these groups cannot be explained by ethnic differences in HAL.

INTRODUCTION

Hip axis length (HAL) has been reported to be an independent predictor of hip fracture. Significant ethnic differences in HAL have been noted, but no direct comparison has been made between African-American, Mexican-American, and non-Hispanic white women using the same protocol.

METHODS

We compared 157 non-Hispanic white women from the Rancho Bernardo Study, 292 women from the Health Assessment Study of African-American Women, and 210 women from the Skeletal Health of Mexican-American Women Project. A standardized questionnaire was used to obtain medical history; height, weight, waist girth, and hip girth were measured; and percentage body fat and HAL were obtained using dual energy X-ray absorptiometry. All HAL comparisons were adjusted for maximum hip girth to control for differences in size magnification by fan-beam absorptiometry.

RESULTS

Though there were ethnic differences in the unadjusted HAL measurement, after adjusting for hip circumference, there were no residual differences in HAL with regard to ethnicity: 10.7 cm in Mexican-American women vs. 10.8 in non-Hispanic white women and African-American women (p = 0.61).

CONCLUSIONS

There were no ethnic differences in HAL in women from the three ethnic groups. Differences in fracture risk among these groups cannot be explained by ethnic differences in HAL.

Catalase as a source of both X- and V-factor for Haemophilus influenzae

Haemophilus influenzae requires two growth factors, designated factor X (porphyrin) and factor V (NAD). Mammalian catalases contain both bound heme and NADPH. This study shows that catalase can supply both factors X and V to H. influenzae in vitro, thus representing a potential in vivo source of these essential growth factors.

Lipoprotein e (P4) of Haemophilus influenzae: role in heme utilization and pathogenesis

Lipoprotein e (P4) of Haemophilus influenzae is a phosphomonoesterase, encoded by the hel gene, that has been implicated in the acquisition of heme by this fastidious organism. However, lipoprotein e (P4) is also involved in the utilization of NAD and NMN. Some reports have concluded that the reported heme-related growth defect actually reflects a growth defect for NAD. In the current study, hel insertion mutants were constructed and a role for e (P4) in heme acquisition was demonstrated independent of its role in NAD or NMN acquisition. In addition, a rat model of infection demonstrated a role for e (P4) in the pathogenesis of invasive disease.

The haem–haemopexin utilization gene cluster (hxuCBA) as a virulence factor of Haemophilus influenzae

Haemophilus influenzae has an absolute growth requirement for a porphyrin source, which can be supplied in vitro by haem, haemoglobin, or the haemoglobin-haptoglobin, haem-haemopexin and haem-albumin complexes. Utilization of the haem-haemopexin complex is known to be mediated by the products of the hxuCBA gene cluster. It was demonstrated that hxuC, but not hxuA or hxuB, is also essential for the utilization of haem from haem-albumin complexes. Mutants of the type b strain E1a lacking genes in the hxuCBA gene cluster were examined for their ability to cause bacteraemia in rat models of invasive disease. In 5-day-old rats, mutants in the hxuCBA genes yielded a significantly reduced bacteraemic titre compared to the wild-type strain. In addition, 5-day-old rats infected with the hxuCBA mutant strains exhibited significantly improved survival rates compared to those infected with the wild-type strain. Mutations in the haemoglobin/haemoglobin-haptoglobin-binding protein genes (hgps), either alone or in combination with the hxuCBA mutations, had no impact on virulence in 5-day-old rats. In 30-day-old rats infected with either the hxuCBA mutants or the wild-type strains, there was no significant difference in the ability to establish bacteraemia although bacterial titres were lower in rats infected with the hxuCBA mutants than in those infected with the wild-type strain. These age-related differences in the impact of mutations in the hxuCBA gene cluster may be related to changes in levels of host haem-binding proteins during development of the rat.

Complex role of hemoglobin and hemoglobin-haptoglobin binding proteins in Haemophilus influenzae virulence in the infant rat model of invasive infection

Haemophilus influenzae requires an exogenous heme source for aerobic growth in vitro. Hemoglobin or hemoglobin-haptoglobin satisfies this requirement. Heme acquisition from hemoglobin-haptoglobin is mediated by proteins encoded by hgp genes. Both Hgps and additional proteins, including those encoded by the hxu operon, provide independent pathways for hemoglobin utilization. Recently we showed that deletion of the set of three hgp genes from a nontypeable strain (86-028NP) of H. influenzae attenuated virulence in the chinchilla otitis media model of noninvasive disease. The present study was undertaken to investigate the role of the hgp genes in virulence of the wild-type serotype b clinical isolate HI689 in the infant rat model of hematogenous meningitis, an established model of invasive disease requiring aerobic growth. Bacteremia of high titer and long duration (>14 days) and histopathologically confirmed meningitis occurred in >95% of infant rats challenged at 5 days of age with strain HI689. While mutations disrupting either the Hgp- or Hxu-mediated pathway of heme acquisition had no effect on virulence in infant rats, an isogenic mutant deficient for both pathways was unable to sustain bacteremia or produce meningitis. In contrast, mutations disrupting either pathway decreased the limited ability of H. influenzae to initiate and sustain bacteremia in weanling rats. Biochemical and growth studies also indicated that infant rat plasma contains multiple heme sources that change with age. Taken together, these data indicate that both the hgp genes and the hxuC gene are virulence determinants in the rat model of human invasive disease.

Transcriptional profile of Haemophilus influenzae: effects of iron and heme

Haemophilus influenzae requires either heme or a porphyrin and iron source for growth. Microarray studies of H. influenzae strain Rd KW20 identified 162 iron/heme-regulated genes, representing approximately 10% of the genome, with > or =1.5-fold changes in transcription in response to iron/heme availability in vitro. Eighty genes were preferentially expressed under iron/heme restriction; 82 genes were preferentially expressed under iron/heme-replete conditions.

Utilization of myoglobin as a heme source by Haemophilus influenzae requires binding of myoglobin to haptoglobin

Haemophilus influenzae has an absolute growth requirement for heme. One potential in vivo source of heme is the protein myoglobin which is found at low levels in human serum. No tested H. influenzae strain was able to use myoglobin as a heme source. However, all strains were able to utilize the heme from myoglobin when myoglobin was complexed with haptoglobin. Utilization of the haptoglobin-myoglobin complex was shown to be mediated by the previously described hemoglobin/hemoglobin-haptoglobin-binding proteins of H. influenzae.

Burkholderia cenocepacia utilizes ferritin as an iron source

Burkholderia cenocepacia is a member of the Burkholderia cepacia complex, a group of genetically similar species that inhabit a number of environmental niches, including the lungs of patients with cystic fibrosis (CF). To colonize the lung, this bacterium requires a source of iron to satisfy its nutritional requirements for this important metal. Because of the high potential for damage in lung tissue resulting from oxygen-iron interactions, this metal is sequestered by a number of mechanisms that render it potentially unavailable to invading micro-organisms. Such mechanisms include the intracellular and extracellular presence of the iron-binding protein ferritin. Ferritin has a highly stable macromolecular structure and may contain up to 4500 iron atoms per molecule. To date, there has been no known report of a pathogenic bacterial species that directly utilizes iron sequestered by this macromolecule. To examine the ability of ferritin to support growth of B. cenocepacia J2315, iron-deficient media were supplemented with different concentrations of ferritin and the growth kinetics characterized over a 40 h period. The results indicated that B. cenocepacia J2315 utilizes iron bound by ferritin. Further studies examining the mechanisms of iron uptake from ferritin indicated that iron utilization results from a proteolytic degradation of this otherwise stable macromolecular structure. Since it is known that the ferritin concentration is significantly higher in the CF lung than in healthy lungs, this novel iron-acquisition mechanism may contribute to infection by B. cenocepacia in people with CF.

Differential utilization by Haemophilus influenzae of haemoglobin complexed to the three human haptoglobin phenotypes

Haemophilus influenzae has an absolute requirement for heme, which may be supplied as the haemoglobin-haptoglobin complex. Utilization of haemoglobin-haptoglobin by H. influenzae is mediated by a family of proteins termed the haemoglobin-haptoglobin binding proteins (Hgps), of which a given strain may contain up to four genes. Human haptoglobin occurs in three phenotypes (1-1, 2-1 and 2-2). Using mutant derivatives of an H. influenzae type b strain that expressed single Hgps we analysed the ability of each Hgp to utilize haemoglobin complexed to the various haptoglobin phenotypes. A strain expressing only HgpB was able to utilize haemoglobin bound to all haptoglobin phenotypes significantly better than strains expressing either HgpA or HgpC.

Identification of an RTX determinant of Burkholderia cenocepacia J2315 by subtractive hybridization

This study utilized suppressive subtractive hybridization between the clinical isolate Burkholderia cenocepacia J2315 and the closely related environmental isolate Burkholderia cepacia ATCC 25416T to isolate DNA fragments specific to B. cenocepacia J2315. Analysis of the resulting pools of B. cenocepacia-specific DNAs identified several fragments that may be part of putative virulence factors. Further in silico analysis of a single fragment indicated that it was internal to a gene of which the predicted product had characteristics of repeat in toxin (RTX)-like proteins and high similarity to proteins in other human or plant pathogens. In conjunction with this finding, phenotypic traits associated with known RTX proteins were assessed. A haemagglutinating activity of B. cenocepacia J2315 was identified that was absent in B. cepacia ATCC 25416T. The expression of this activity appeared to be growth phase-dependent. Analysis of the gene presence and haemagglutinating activity across the species of the B. cepacia complex showed that both were common to the ET12 lineage of B. cenocepacia, but were absent in the other species examined. Haemagglutinating activity was limited to isolates with the RTX-like gene. Expression studies utilizing quantitative PCR demonstrated an association between onset of haemagglutinating activity and increased expression of the gene, which suggests that the putative RTX determinant encodes a haemagglutinating activity.

The heme-binding lipoprotein (HbpA) of Haemophilus influenzae: role in heme utilization

Haemophilus influenzae has an absolute growth requirement for heme and a heme binding lipoprotein (HbpA) has been implicated in the utilization of this essential nutrient. HbpA was identified by examining clones from an H. influenzae genomic library that caused Escherichia coli harboring the clone to bind heme. However, HbpA has not been shown to mediate heme acquisition in H. influenzae. We constructed an insertional mutation of hbpA in a nontypeable H. influenzae strain and demonstrated a role for the gene in utilization of multiple heme sources. This is the first report confirming a role for HbpA in utilization of heme.

Identification of a haem-utilization protein (Hup) in Haemophilus influenzae

Haemophilus influenzae has an absolute growth requirement for a porphyrin source. This growth requirement can be satisfied in vitro by haem, haemoglobin or the haemoglobin-haptoglobin, haem-haemopexin and haem-albumin complexes. A family of proteins, termed the Hgp proteins, which are essential for utilization of the haemoglobin-haptoglobin complex, has previously been identified. A strain lacking the Hgp proteins also has a residual ability to utilize haemoglobin, indicating that additional moieties contribute to haemoglobin utilization. Using a haemoglobin affinity method an approximately 105 kDa protein was isolated. Mutation of the identified gene in an Hgp null background reduced the ability of the mutant strain to utilize haemoglobin in vitro. The mutation also resulted in a reduced ability to utilize haem, haem-haemopexin, haem-albumin and haemoglobin-haptoglobin, thus identifying a general haem-utilization protein (Hup) in Haemophilus influenzae.

Characterization of three new competence-regulated operons in Haemophilus influenzae

Haemophilus influenzae is one of a growing number of bacteria in which the natural ability to uptake exogenous DNA for potential genomic transformation has been recognized. To date, several operons involved in transformation in this organism have been described. These operons are characterized by a conserved 22-bp regulatory element upstream of the first gene and are induced coincident with transfer from rich to nutrient-depleted media. The previously identified operons comprised genes encoding proteins that include members of the type II secretion system and type IV pili, shown to be essential for transformation in other bacteria, and other proteins previously identified as required for transformation in H. influenzae. In the present study, three novel competence operons were identified by comparative genomics and transcriptional analysis. These operons have been further characterized by construction of null mutants and examination of the resulting transformation phenotypes. The putative protein encoded by the HI0366 gene was shown to be essential for DNA uptake, but not binding, and is homologous to a protein shown to be required for pilus biogenesis and twitching motility in Pseudomonas aeruginosa. An insertion in HI0939 abolished both DNA binding and uptake. The predicted product of this gene shares characteristics with PulJ, a pseudopilin involved in pullulanase export in Klebsiella oxytoca.

Reduced severity of middle ear infection caused by nontypeable Haemophilus influenzae lacking the hemoglobin/hemoglobin–haptoglobin binding proteins (Hgp) in a chinchilla model of otitis media

Since Haemophilus influenzae lacks enzymes necessary for synthesis of the porphyrin ring, it has an absolute growth requirement for a porphyrin source. This requirement can be satisfied in vitro by hemoglobin and hemoglobin complexed to haptoglobin. The products of the hgp genes mediate the utilization of heme from hemoglobin-haptoglobin. These genes are also involved in the use of heme from hemoglobin, although additional gene products independently mediate the acquisition of heme from this substrate. Different strains of H. influenzae possess one to four hgp genes. A nontypeable H. influenzae mutant lacking all the hgp genes was constructed and compared to the wild-type strain in a chinchilla (Chinchilla lanigera) model of otitis media. Compared to the wild-type strain, the hgp-deficient mutant exhibited a significantly delayed onset of detectable middle ear infection and significantly reduced duration of infection as assessed by both video otoscopy and tympanometry and as evidenced by viable bacterial counts in middle ear effusions. In addition, the maximum bacterial load in the middle ears of chinchillas infected with the mutant strain was significantly reduced when compared to the parent. These data indicate that the hemoglobin/hemoglobin-haptoglobin binding proteins are required for bacterial proliferation during H. influenzae-induced otitis media in chinchillas.

Vitamin C supplement use and bone mineral density in postmenopausal women

Vitamin C is known to stimulate procollagen, enhance collagen synthesis, and stimulate alkaline phosphatase activity, a marker for osteoblast formation. Studies of dietary vitamin C intake and the relation with bone mineral density (BMD) have been conflicting, probably because of the well-known limitations of dietary nutrient assessment questionnaires. The purpose of this study was to evaluate the independent relation of daily vitamin C supplement use with BMD in a population-based sample of postmenopausal women. Subjects were 994 women from a community-based cohort of whom 277 women were regular vitamin C supplement users. Vitamin C supplement use was validated. Daily vitamin C supplement intake ranged from 100 to 5,000 mg; the mean daily dose was 745 mg. Average duration of use was 12.4 years; 85% had taken vitamin C supplements for more than 3 years. BMD levels were measured at the ultradistal and midshaft radii, hip, and lumbar spine. After adjusting for age, body mass index (BMI), and total calcium intake, vitamin C users had BMD levels approximately 3% higher at the midshaft radius, femoral neck, and total hip (p < 0.05). In a fully adjusted model, significant differences remained at the femoral neck (p < 0.02) and marginal significance was observed at the total hip (p < 0.06). Women taking both estrogen and vitamin C had significantly higher BMD levels at all sites. Among current estrogen users, those also taking vitamin C had higher BMD levels at all sites, with marginal significance achieved at the ultradistal radius (p < 0.07), femoral neck (p < 0.07), and total hip (p < 0.09). Women who took vitamin C plus calcium and estrogen had the highest BMD at the femoral neck (p = 0.001), total hip (p = 0.05), ultradistal radius (p = 0.02), and lumbar spine. Vitamin C supplement use appears to have a beneficial effect on levels of BMD, especially among postmenopausal women using concurrent estrogen therapy and calcium supplements.

Lower extremity arterial disease in older women: the Rancho Bernardo Study

Most studies of lower extremity arterial disease (LEAD) have not included women. To study the frequency of LEAD and its association with cardiovascular disease risk factors and estrogen use in community-dwelling postmenopausal women, we conducted a cross-sectional study of LEAD in 826 women whose average age was 74 years. Cardiovascular disease risk factors and medical history, body mass index (BMI), blood pressure, glucose tolerance, lipids and lipoproteins, and current and past medication use were determined using a standard protocol. Ankle-brachial artery index (ABI) of systolic blood pressure was measured by a trained technician using Doppler ultrasound. LEAD was defined as ABI <0.8. LEAD prevalence increased with age from nearly 5% in the 60-69-year-old group to >25% in women aged 90 and older. In age-adjusted analyses, women with LEAD had significantly lower levels of high-density lipoprotein (HDL) cholesterol, were less likely to exercise regularly, and were less likely to have ever used estrogen replacement therapy. They also had significantly higher levels of blood pressure, low-density lipoprotein (LDL) cholesterol, triglycerides, glucose, and insulin. In multivariate analyses, high HDL cholesterol, regular exercise, and estrogen use were each associated with a reduced risk of LEAD, whereas age, high blood pressure, and abnormal glucose tolerance were each associated with increased risk. Few women (6%) were smokers, but they had twice the risk of LEAD compared with nonsmokers. Estrogen was independently associated with LEAD in a model containing all covariates except LDL and HDL, and this association was no longer significant in a second model adjusting for these lipoproteins. LEAD is common in older women and associated with modifiable risk factors. The apparent protection associated with estrogen should be studied in clinical trials.

Birth weight as a predictor of adult bone mass in postmenopausal women: the Rancho Bernardo Study

Understanding the determinants of adult bone mass may help to identify women for prevention of osteoporosis. We postulated that birth weight would predict low adult bone mass in old age. Subjects were 305 postmenopausal Caucasian women (mean age 70 years). Bone mineral content (BMC) and bone mineral density (BMD) were measured at the wrist, forearm, hip and lumbar spine. Birth weight was assessed by self-report. Birth weight was positively correlated with BMC at the forearm (r = 0.15), hip (r = 0.12) and lumbar spine (r = 0.18), and the age-adjusted mean BMC increased significantly from the lowest to the highest birth weight tertile. Adjusting for adult weight diminished this association at the forearm and hip, but not at the spine. Adjustment for multiple other covariates, including height, did not materially change these associations. Adult weight and height were significantly correlated with birth weight (r = 0.19 and r = 0.24, respectively). Birth weight was not independently correlated with BMD. Birth weight was thus positively correlated with adult weight and BMC 70 years later. These findings suggest that low birth weight may be a marker for future low bone mass and that different mechanisms exist for establishing the adult bone envelope (estimated by BMC) versus its density (estimated by BMD).

Role of CCAA nucleotide repeats in regulation of hemoglobin and hemoglobin-haptoglobin binding protein genes of Haemophilus influenzae

Haemophilus influenzae utilizes hemoglobin and hemoglobin-haptoglobin as heme sources. The H. influenzae hemoglobin- and hemoglobin-haptoglobin binding protein genes, hgpA, hgpB, and hgpC, contain lengths of tetrameric CCAA repeats. Using an hgpA-lacZ translational gene fusion, we demonstrate phase-variable expression of lacZ associated with alteration in the length of the CCAA repeat region.

Quality of care for patients hospitalized with heart failure at academic medical centers

BACKGROUND

The purpose of this study was to determine the standard of care provided by academic medical centers for the management of congestive heart failure (CHF).

METHODS AND RESULTS

The standard of care was estimated by assessing adherence to the treatment guidelines published by the US Agency for Health Care Policy and Research among 522 patients hospitalized at 7 university hospitals with a diagnosis of CHF. Data were abstracted by retrospective chart review. Of the 522 patients analyzed, 435 (83%) had a left ventricular ejection fraction (LVEF) measured or documented. Among these patients, 192 were considered "ideal" candidates for angiotensin-converting enzyme (ACE) inhibitor therapy (ie, with systolic dysfunction [LVEF <40%] and no contraindications to ACE inhibitors). In this cohort of "ideal" candidates, 138 (72%) were receiving ACE inhibitors at hospital discharge, including 60 (44%) who were prescribed doses recommended in large clinical trials. Compliance with patient education guidelines was assessed in all 487 patients who were alive at the time of discharge. Of these patients, 365 (75%) received dietary counseling, 404 (83%) were educated about exercise, 54 (11%) were instructed to follow daily weights, and 468 (96%) were counseled regarding medication compliance. Among the 87 smokers who were alive at time of discharge, 8 (9%) had documented advice to quit smoking.

CONCLUSIONS

This study indicates that academic medical centers performed fairly well on the assessment of LVEF, the prescription of ACE inhibitors at discharge, and on education regarding diet, exercise, and compliance with medications. However, the results suggest opportunities for improvement in ACE inhibitor dosing and patient education regarding the importance of monitoring daily weights and smoking cessation.

Effect of multiple mutations in the hemoglobin- and hemoglobin-haptoglobin-binding proteins, HgpA, HgpB, and HgpC, of Haemophilus influenzae type b

Haemophilus influenzae requires heme for growth and can utilize hemoglobin and hemoglobin-haptoglobin as heme sources. We previously identified two hemoglobin- and hemoglobin-haptoglobin-binding proteins, HgpA and HgpB, in H. influenzae HI689. Insertional mutation of hgpA and hgpB, either singly or together, did not abrogate the ability to utilize or bind either hemoglobin or the hemoglobin-haptoglobin complex. A hemoglobin affinity purification method was used to isolate a protein of approximately 120 kDa from the hgpA hgpB double mutant. We have cloned and sequenced the gene encoding this third hemoglobin/hemoglobin-haptoglobin binding protein and designate it hgpC. Insertional mutation of hgpC did not affect the ability of the strain to utilize either hemoglobin or hemoglobin-haptoglobin. An hgpA hgpB hgpC triple mutant constructed by insertional mutagenesis showed a reduced ability to use the hemoglobin-haptoglobin complex but was unaltered in the ability to use hemoglobin. A second class of mutants was constructed in which the entire structural gene of each of the three proteins was deleted. The hgpA hgpB hgpC complete-deletion triple mutant was unable to utilize the hemoglobin-haptoglobin complex and showed a reduced ability to use hemoglobin. We have identified three hemoglobin/hemoglobin-haptoglobin-binding proteins in Haemophilus influenzae. Any one of the three proteins is sufficient to support growth with hemoglobin-haptoglobin as the heme source, and expression of at least one of the three is essential for hemoglobin-haptoglobin utilization. Although the three proteins play a role in hemoglobin utilization, an additional hemoglobin acquisition mechanism(s) exists.

Distribution of a family of Haemophilus influenzae genes containing CCAA nucleotide repeating units

A family of genes containing lengths of CCAA nucleotide repeating units directly following the sequence encoding the leader peptide has been identified in Haemophilus influenzae. The length of the CCAA repeats ranges from 6 to 43 and all of the identified genes encode proteins or predicted proteins with a significant homology to bacterial iron- or heme-related outer membrane proteins. We have previously shown that two of these gene products, HgpA and HgpB, bind hemoglobin and the hemoglobin-haptoglobin complex. Studies were performed to define the species distribution of the five identified genes and the CCAA repeats. We show that both the CCAA motif and the structural genes for hemoglobin and hemoglobin-haptoglobin binding are widely distributed among H. influenzae strains.

Characterization of hgpA, a gene encoding a haemoglobin/haemoglobin-haptoglobin-binding protein of Haemophilus influenzae

Haemophilus haemoglobin-haptoglobin complex and utilizes either as a sole source of haem. Previously, a DNA fragment was cloned from H. influenzae that encodes an approximately 120 kDa protein (HgpA) expressing haemoglobin-binding activity in Escherichia coli. Partial sequence analysis revealed significant homology of HgpA with other bacterial haem- and iron-utilization proteins, and a length of CCAA repeating units immediately following the nucleotide sequence encoding the putative leader peptide. In the present study, the complete nucleotide sequence of the cloned DNA fragment was determined and the sequence was analysed. In addition to homology with other haem- and iron-utilization proteins, seven regions typical of TonB-dependent proteins were identified. The transcript of hgpA was determined to be monocistronic by RT-PCR. PCR performed with different colonies of a single H. influenzae strain at one CCAA-repeat-containing locus indicated varying lengths of CCAA repeats, suggesting that haemoglobin and haemoglobin-haptoglobin binding in H. influenzae is regulated by strand slippage across CCAA repeats, as well as by haem repression. E. coli containing cloned hgpA bound both haemoglobin and the haemoglobin-haptoglobin complex. A deletion/insertion mutation of hgpA was constructed in H. influenzae strain H1689. Mutation of hgpA did not affect the ability of H. influenzae either to bind or to utilize haemoglobin or haemoglobin-haptoglobin following growth in haem-deplete media. Affinity purification of haemoglobin-binding proteins from the mutant strain revealed loss of the 120 kDa protein and an increased amount of a 115 kDa protein, suggesting that at least one additional haemoglobin-binding protein exists.

Nonsteroidal anti-inflammatory drugs and bone mineral density in older women: the Rancho Bernardo study

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to inhibit synthesis of prostaglandins and may help prevent bone loss, but no study has shown the differential association of type or dose of NSAID compound with bone mineral density (BMD). The purpose of this study was to determine the relation of NSAIDs by type and dose to BMD. Participants were 932 Caucasian, community-dwelling women aged 44-98 years from southern California. Data were collected from 1988 to 1991 through the use of standardized medical questionnaires. Medication use was validated by a nurse. BMD at the ultradistal and midshaft radii were measured using single-photon absorptiometry, and at the hip and lumbar spine using dual-energy X-ray absorptiometry. Women (mean age, 72 years) were classified into 818 nonusers and 114 regular daily users of NSAIDs, of which 84 used propionic acid NSAIDs and the remainder used acetic acid NSAIDs. Occasional NSAID users were excluded. Women who used propionic acid NSAIDs, but not acetic acid NSAIDs, had higher BMD at all five sites and significantly higher BMD at the midshaft radius and lumbar spine. These differences remained after controlling for known covariates of osteoporosis. When women with self-reported osteoarthritis were excluded from the model, significantly higher BMD in propionic acid NSAID users was also observed at the femoral neck and total hip. Those who concurrently used estrogen and propionic acid NSAIDs had the highest BMD at all sites, suggesting an additive effect. We conclude that regular daily use of propionic acid NSAIDs, with or without simultaneous use of estrogen, may be helpful in preventing bone loss in older women. However, further research is needed to confirm these results before any clinical practice guidelines can be recommended due to the increased risk of serious complications associated with NSAID use.

hgpB, a gene encoding a second Haemophilus influenzae hemoglobin- and hemoglobin-haptoglobin-binding protein

Haemophilus influenzae requires heme for growth and can utilize both hemoglobin and hemoglobin-haptoglobin as heme sources. We previously identified a hemoglobin- and hemoglobin-haptoglobin-binding protein, HgpA, in H. influenzae HI689. Mutation of hgpA did not affect binding or utilization of either heme source. The hgpA mutant exhibited loss of a 120-kDa protein and increased expression of a 115-kDa protein. These data suggested that at least one other gene product is involved in binding of these heme sources by H. influenzae. A 3.2-kbp PCR product derived from HI689 was cloned. The nucleotide sequence indicated a separate, distinct gene with high homology to hgpA, which would encode a 115-kDa protein. Primers were designed for directional cloning of the structural gene in the correct reading frame. Sonicates of induced Escherichia coli harboring the cloned open reading frame bound both hemoglobin and hemoglobin-haptoglobin. An insertion/deletion mutant of H. influenzae at the newly identified locus, designated hgpB, was constructed. The 115-kDa protein was not detected in the mutant after affinity purification using biotinylated hemoglobin. An hgpA hgpB double-mutant strain exhibited a reduced ability to utilize hemoglobin-haptoglobin, although it was unaltered in the ability to utilize hemoglobin. Affinity isolation of hemoglobin-binding proteins from the double mutant resulted in isolation of an approximately 120-kDa protein. Internal peptide sequencing revealed this protein to be a third distinct protein, highly homologous to HgpA and HgpB. In summary a second hemoglobin- and hemoglobin-haptoglobin-binding protein of H. influenzae has been identified and characterized, and the presence of an additional protein of similar function has been revealed.

Construction of antibiotic resistance cassettes with multiple paired restriction sites for insertional mutagenesis of Haemophilus influenzae

Insertional mutagenesis of cloned genes coupled with site specific recombination into the genome of the parent organism is an ideal method for characterizing gene function. In this paper we describe the production and utility of two antibiotic resistance cassettes for use in Haemophilus influenzae. The mutagenic elements encode resistance to chloramphenicol or spectinomycin. Multiple paired restriction enzyme sites bound both cassettes. Use of these constructs to create mutants in H. influenzae demonstrated that the cassettes are readily incorporated into the genome in single copy and allow easy detection of mutant constructs. The insertions are stable following repeated in vitro passage. In addition, the elements are compatible with each other and allow the construction of multiple mutations within a single strain.

Serum albumin and bone mineral density in healthy older men and women: the Rancho Bernardo Study

Serum albumin has been found to be positively correlated with bone mass in small studies of ambulatory men or women with diagnosed osteoporosis. In this study the relation between serum albumin and bone mineral density (BMD) was examined in 1593 white, community-dwelling men and women aged 50-95 years. BMD was determined using single-photon absorptiometry (SPA) at the ultradistal radius and the midshaft radius, and using dual-energy X-ray absorptiometry (DXA) at the hip and spine. Albumin was measured from a fasting blood sample using the Technicon SMA 12 autoanalyzer. Mean albumin levels in both men and women decreased significantly with increasing age. All but four values were within the normal range (3.5-5.0 g/dl). BMD decreased with increasing age at all sites. In both sexes there was weak positive correlation between serum albumin and BMD in the unadjusted model (Pearson's r values < 0.3, p values < 0.005). After age adjustment, however, the relationship was no longer significant (Pearson's r values < 0.05, p values > 0.18). Men and women were divided into three sex-specific categories--osteoporotic, osteopenic and normal--based on World Health Organization criteria in relation to young adult means (normal, BMD > -1 SD; osteopenia, BMD between -1 SD and -2.5 SD; osteoporosis, BMD < -2.5 SD). Mean albumin values did not differ significantly across the three BMD categories in men or women. BMD levels stratified for albumin levels and calcium supplement status (a marker for osteoporosis awareness) also did not differ. Albumin levels were also not associated with a history of low-trauma fractures. In summary, there was no age-independent association between serum albumin within the normal range and low BMD or fractures in community-dwelling healthy older adults. We conclude that previously reported associations most likely reflect inadequate adjustment for the age-related decrease in albumin levels and the selection of very frail osteoporotic subjects.

Transcription of genes encoding iron and heme acquisition proteins of Haemophilus influenzae during acute otitis media

Unencapsulated Haemophilus influenzae is the second most common etiologic agent of otitis media in children. H. influenzae requires heme for aerobic growth in vitro and is able to utilize hemoglobin and complexes of heme-hemopexin, heme-albumin, and hemoglobin-haptoglobin and ferritransferrin as sources of iron and heme in vitro. Several of the acquisition mechanisms have been characterized and been shown to be heme repressible in vitro. However, little is known about the expression of heme and/or iron acquisition mechanisms during infections in the middle ear. This study was performed to determine if the genes encoding heme and iron acquisition proteins are transcribed during in vivo growth and to compare these findings with those for samples grown in vitro. Reverse transcriptase PCR (RT-PCR) was used to analyze total RNA fractions derived from in vitro- and in vivo-grown H. influenzae. Genes encoding the transferrin-binding proteins TbpA and TbpB, the 100-kDa hemopexin-binding protein HxuA, and the hemoglobin-binding protein HgpA were transcribed during otitis media. Twelve middle ear fluid samples were analyzed by blind RT-PCR to determine the transcriptional status of these genes in H. influenzae during otitis media. Five isolates had transcripts corresponding to tbpA, tbpB, and hxuA. The presence of hgpA transcripts was variable, depending on the presence of hgpA in the genome of the H. influenzae isolate. Samples without H. influenzae gene transcripts contained other etiologic agents commonly causing otitis media. These data demonstrate that H. influenzae iron and/or heme acquisition genes are transcribed during otitis media and suggest that the microenvironment during acute otitis media starves H. influenzae of heme.

Economic impact of digoxin toxicity

The costs of digoxin toxicity to the US healthcare system have not been previously reported. Therefore, the 1994 database of US University Health-System Consortium (UHC) was searched for cases of digoxin toxicity using the International Classification of Diseases (9th edition) [ICD-9] codes. In addition, the medical records of 17 patients admitted to the University of Illinois Hospital from September 1994 to July 1995 with a diagnosis of digoxin toxicity were also reviewed. Of the 17 patients, 14 were admitted with a primary diagnosis of digoxin toxicity. Causes of digoxin toxicity were worsening renal function (6 patients), excessive dosage prescribed (4 patients), excessive dosage self-administered (2 patients), multiple prescriptions (2 patients), accidental ingestion (1 patient), drug-drug interaction (1 patient) and unknown (1 patient). Digoxin toxicity could have been prevented in 9 (53%) of the 17 patients. The mean length of stay in the hospital as a result of digoxin toxicity was 3.3 +/- 1.2 days. The mean laboratory cost associated with digoxin toxicity was $US275.54 +/- $US106.57 and the mean hospital bed cost was $US3781.92 +/- $US2572.22. The mean overall cost associated with digoxin toxicity was $US4087.05 +/- $US2659.76. There was a significant correlation between the total cost associated with digoxin toxicity and the serum digoxin concentration on admission (r = 0.73, p < 0.01). From the UHC database, a total of 836 cases of digoxin toxicity in 56 hospitals were identified. This represented the occurrence of digoxin toxicity in 0.07% of all patients admitted to these US academic hospitals. Digoxin toxicity results in considerable costs to the healthcare system. Most cases can be considered readily preventable with proper patient counselling and education.

Clinical characteristics and management of acute stroke in patients with atrial fibrillation admitted to US university hospitals

The optimal evaluation and management of patients with atrial fibrillation who suffer an acute ischemic stroke remains controversial.

METHODS

Medical records of 171 consecutive patients with atrial fibrillation and acute stroke at six U.S. university hospitals were reviewed. Data collected included the use of antithrombotic therapy, brain and cardiac imaging, bleeding complications, stroke risk factors, and contraindications to anticoagulation.

RESULTS

Mean age was 75.4 years. Cardiovascular risk factors associated with increased stroke risk were present in 87%; 35% had at least one contraindication to anticoagulation. Half of the patients with stroke risk factors and no contraindications to anticoagulation were not receiving any antithrombotic therapy at the time of admission. Of the 22 patients who were treated with warfarin, and had INR values on admission, 16 had levels of < 2.0; only six had INR values between 2.0 and 3.0. Transthoracic echocardiography was performed in 107 patients (63%); intracardiac thrombi were visualized in only 5%. Initial brain imaging revealed hemorrhagic transformation in nine. Heparin was used in 93 patients (54%), usually within 48 hours of stroke onset. Patients who received delayed heparin typically did not have repeat brain imaging prior to starting heparin. One patient had a delayed symptomatic cerebral hemorrhage. Of the survivors, 47% were discharged and treated with warfarin (or warfarin plus aspirin), 28% with ASA, 7% with other antithrombotic therapies, and 18% with no antithrombotic therapy.

CONCLUSION

Antithrombotic therapy was underutilized and inadequately monitored in atrial fibrillation patients prior to stroke onset. After hospital admission, a wide range of diagnostic and management strategies, which often did not follow current recommendations, were employed.

Timing of postmenopausal estrogen for optimal bone mineral density. The Rancho Bernardo Study

OBJECTIVE

To determine the effect of the timing of initiation and the duration of postmenopausal estrogen therapy on bone mineral density (BMD).

DESIGN

Cross-sectional study.

SETTING

White, middle-class to upper middle-class community-dwelling women.

PARTICIPANTS

A total of 740 women aged 60 to 98 years who participated in a study of osteoporosis.

MEASUREMENTS

Questionnaire, validated medication use, and height and weight. Bone mineral density at the ultradistal radius and midshaft radius using single-photon absorptiometry (SPA) and at the hip and lumbar spine using dual-energy x-ray absorptiometry (DEXA).

RESULTS

Of the 740 women, 69% had used oral estrogen after menopause and 30% were current users. Five groups of estrogen use were identified: never users, past users who started at menopause, past users who started after age 60 years, current users who started after age 60 years, and current users who started at menopause. At all 4 bone sites, current users who started at menopause had the highest BMD levels, which were significantly higher than never users or past users who started at menopause (with 10 years' duration of use). These differences persisted after controlling for all major risk factors for osteoporosis. Among current users, there was no significant difference in BMD levels at any site between those who started estrogen at menopause (with 20 years of use) and those who started after age 60 years (with 9 years of use).

CONCLUSIONS

Estrogen initiated in the menopausal period and continued into late life is associated with the highest bone density. Nevertheless, estrogen begun after age 60 years and continued appears to offer nearly equal bone-conserving benefit.

Carbonated beverage consumption and bone mineral density among older women: the Rancho Bernardo Study

OBJECTIVES

The association between carbonated beverage consumption and bone mineral density was examined in a community-based cohort of older White women.

METHODS

One thousand women 44 to 98 years of age had bone mineral density measured at four sites and provided medical and behavioral histories, including type and quantity of carbonated beverages consumed.

RESULTS

Bone mineral density levels were not associated with intake of any type of carbonated beverage after adjustment for age, obesity, calcium intake, exercise, and current use of tobacco and alcohol, thiazides, estrogen, or thyroid hormone.

CONCLUSIONS

Modest intake of carbonated beverages does not appear to have adverse effects on bone mineral density in older women.

Status of antithrombotic therapy for patients with atrial fibrillation in university hospitals

BACKGROUND

The risk of stroke in patients with atrial fibrillation can be significantly reduced with antithrombotic therapy. Despite this, many physicians remain hesitant to prescribe warfarin sodium or aspirin therapy for patients with atrial fibrillation.

OBJECTIVE

To assess the use of antithrombotic therapy in patients with atrial fibrillation at 6 academic hospitals in the United States.

METHODS

Records were reviewed from consecutive hospital admissions of 309 patients with atrial fibrillation at 6 members of the University Health System Consortium, Oak Brook, III, which is a member driven alliance of 70 academic health centers in the United States. Risk factors for stroke, contraindications to anticoagulant therapy, and use of antithrombotic therapy at admission and discharge were recorded.

RESULTS

The mean age of patients was 71.6 years, 54% had chronic, 22% paroxysmal, and 24% new-onset atrial fibrillation. Eighty-two percent of the patients had cardiovascular risk factors that have been associated with increased risk of stroke. At least 1 relative contraindication to anticoagulant therapy was present in 44%. At the time of admission. 32% of the patients with previously diagnosed atrial fibrillation (n = 235) were receiving warfarin (or warfarin plus aspirin), 31% were receiving aspirin alone, and 36% were receiving no antithrombotic therapy. At discharge (n = 230), 41% of these patients were taking warfarin (or warfarin plus aspirin) and 36% were taking aspirin. Forty-four percent of the patients with risk factors for stroke and no contraindications to anticoagulation (n = 134) were discharged on a regimen of warfarin (or warfarin plus aspirin), 34% were discharged on a regimen of aspirin, and 22% received no antithrombotic therapy.

CONCLUSIONS

About half of the patients with atrial fibrillation admitted to these academic hospitals had clinical risk factors that are associated with increased risk of stroke and no contraindications to anticoagulation. Antithrombotic therapy was underused in these patients.

Cloning of a DNA fragment encoding a heme-repressible hemoglobin-binding outer membrane protein from Haemophilus influenzae

Haemophilus influenzae is able to use hemoglobin as a sole source of heme, and heme-repressible hemoglobin binding to the cell surface has been demonstrated. Using an affinity purification methodology, a hemoglobin-binding protein of approximately 120 kDa was isolated from H. influenzae type b strain HI689 grown in heme-restricted but not in heme-replete conditions. The isolated protein was subjected to N-terminal amino acid sequencing, and the derived amino acid sequence was used to design corresponding oligonucleotides. The oligonucleotides were used to probe a Southern blot of EcoRI-digested HI689 genomic DNA. A hybridizing band of approximately 4.2 kb was successfully cloned into pUC19. Using a 1.9-kb internal BglII fragment of the 4.2-kb clone as a probe, hybridization was seen in both typeable and nontypeable H. influenzae but not in other bacterial species tested. Following partial nucleotide sequencing of the 4.2-kb insert, a putative open reading frame was subcloned into an expression vector. The host Escherichia coli strain in which the cloned fragment was expressed bound biotinylated human hemoglobin, whereas binding of hemoglobin was not detected in E. coli with the vector alone. In conclusion, we hypothesize that the DNA fragment encoding an approximately 120-kDa heme-repressible hemoglobin-binding protein mediates one step in the acquisition of hemoglobin by H. influenzae in vivo.