Steatohepatitis due to antiretroviral therapy

Jamaica has recorded the largest increase in the rate of HIV/AIDS infection in the English-speaking Caribbean since 1985. Treatment has significantly improved recently with approximately 50% availability of antiretrovirals (ARVs) to patients. The incidence of drug induced hepatotoxicity is not well known for most ARV drugs and few studies have assessed adverse drug effects in clinical practice. A patient with HIV on highly active antiretroviral therapy (HAART) presented with a one year history of progressive abdominal distension. Abdominal examination revealed a 17 cm, smooth, non-tender liver with a rounded edge; 12 cm of which was below the right costal margin. Liver enzymes were grossly abnormal. The liver biopsy revealed parenchymal distortion by fibrosis with macrovesicular fatty change and Mallory's hyaline in keeping with steatohepatitis. Follow-up studies after discontinuation of stavudine revealed that the liver enzymes improved within four months. Physicians should be mindful of the hepatotoxic potential of ARVs and monitor liver enzymes in HIV-infected patients on therapy.

From quadruplex to helix and back: meta-stable states can move through a cycle of conformational changes

Strand displacement cycles can be driven by sequential addition of short oligonucleotide sequences. Successive inter- and intra-molecular interactions based on the rules of Watson-Crick base pairing allow us to design self-assembling molecular systems with predictable folding pathways and conformational changes. Here we present a particular strand displacement cycle that starts from a tethered quadruplex-forming sequence from the human telomere repeat (T(2)AG(3))(4) that forms a G-quartet within a stem-loop structure. Adding an almost matching single strand converts the four-stranded section into a defective double helix. This is the first step of the cycle. The subsequent addition of a "fuel strand" removes the single strand from the loop sequence in favor of a perfect double helix. This displacement frees the hairpin-loop to go back to its initial state. Analysis of this cycle, that resembles an enzyme-substrate pathway as far as the initial state will be regained at the end of the cycle, advances our understanding of the interchanges between meta-stable states that underlie some fundamental steps in molecular biology, and allow for the construction of nano-molecular machines.

Progress in designing nucleic acid structures and fine-tuning their interactions

The prediction of the structure of biological macromolecules at the atomic level and the design of new meta-stable structures and secondary interactions are critical tests of our understanding of the structures and the inter-atomic forces that underlie molecular biology. The capacity to accurately predict and design new structures and interactions will allow us to create nucleic acid sequences that will fold in new and useful ways. Here, we present some results to demonstrate the progress we have made in designing and assembling new nucleic acid structures that will make an increasingly important contribution to biology and medicine. We call the reaction cycle that exemplifies our approach 'A handshake from a hairpin on the way to a double helix.'

Relation of contraceptive and reproductive history to ovarian cancer risk in carriers and noncarriers of BRCA1 gene mutations

In the general population, ovarian cancer risk is inversely associated with oral contraceptive use, tubal ligation, and childbearing. Among carriers of BRCA1 gene mutations, the data are conflicting. The authors identified women diagnosed with incident invasive epithelial ovarian cancer in the San Francisco Bay Area of California from March 1997 through July 2001. They compared the contraceptive and reproductive histories of 36 carrier cases and 381 noncarrier cases with those of 568 controls identified by random digit dialing who were frequency matched to cases on age and race/ethnicity. In both carriers and noncarriers, reduced risk was associated with ever use of oral contraceptives (odds ratio = 0.54 (95% confidence interval (CI): 0.26, 1.13) for carriers and 0.55 (95% CI: 0.41, 0.73) for noncarriers), duration of oral contraceptive use (risk reduction per year = 13% (p = 0.01) for carriers and 6% (p < 0.001) for noncarriers), history of tubal ligation (odds ratio = 0.68 (95% CI: 0.25, 1.90) for carriers and 0.65 (95% CI: 0.45, 0.95) for noncarriers), and increasing parity (risk reduction per childbirth = 16% (p = 0.26) for carriers and 24% (p < 0.001) for noncarriers). These data suggest that BRCA1 mutation carriers and noncarriers have similar risk reductions associated with oral contraceptive use, tubal ligation, and parity.

Urinary compounds in autism

BACKGROUND

Although earlier claims to identify specific compounds in the urine of people with autism had been discredited, it was subsequently suggested that there might be biochemical characteristics that were specific to early childhood, particularly in those who also did not have a severe degree of intellectual disability This study was to establish whether autism might have a distinctive chromatographic profile on urinary analysis.

METHOD

Thirty-four prepubertal boys with autism were matched with two groups of boys without autism--one on ability and chronological age and the other on chronological age alone, being within the normal range of ability. Laboratory analysis of their urine samples was carried out blind as to the clinical diagnosis.

RESULTS

The analysis correctly identified 53% of the autism group as against misidentifying 33% and 18% of the other two groups. When children with a severe learning disability (both with and without autism) were excluded from the comparisons, the laboratory then identified 77% of the 13 boys left in the autism group and misidentified 8% and 18% of the other two groups.

CONCLUSIONS

The results would support the idea of a biological marker in prepubertal children and that it may be absent in, or obscured by the presence of severe LD.

Evaluation of the BAX system for detection of Listeria monocytogenes in foods: collaborative study

A multilaboratory study was conducted to compare the automated BAX system and the standard cultural methods for detection of Listeria monocytogenes in foods. Six food types (frankfurters, soft cheese, smoked salmon, raw, ground beef, fresh radishes, and frozen peas) were analyzed by each method. For each food type, 3 inoculation levels were tested: high (average of 2 CFU/g), low (average of 0.2 CFU/g) and uninoculated controls. A total of 25 laboratories representing government and industry participated. Of the 2335 samples analyzed, 1109 were positive by the BAX system and 1115 were positive by the standard method. A Chi square analysis of each of the 6 food types, at the 3 inoculation levels tested, was performed. For all foods, except radishes, the BAX system performed as well as or better than the standard reference methods based on the Chi square results.

Contrast letter acuity as a visual component for the Multiple Sclerosis Functional Composite

BACKGROUND

Visual dysfunction is one of the most common causes of disability in multiple sclerosis (MS). The Multiple Sclerosis Functional Composite (MSFC), a new clinical trial outcome measure, does not currently include a test of visual function.

OBJECTIVE

To examine contrast letter acuity as a candidate visual function test for the MSFC.

METHODS

Binocular contrast letter acuity testing (Sloan charts) was performed in a subgroup of participants from the International Multiple Sclerosis Secondary Progressive Avonex Controlled Trial (IMPACT Substudy) and in MS patients and disease-free control subjects from a cross-sectional study of visual outcome measures (Multiple Sclerosis Vision Prospective cohort [MVP cohort]). High-contrast visual acuity was measured in both studies; MVP cohort participants underwent additional binocular testing for contrast sensitivity (Pelli-Robson chart), color vision (D-15 desaturated test), and visual field (Esterman test, Humphrey Field Analyzer II).

RESULTS

Contrast letter acuity (Sloan charts, p < 0.0001, receiver operating characteristic curve analysis) and contrast sensitivity (Pelli-Robson chart, p = 0.003) best distinguished MS patients from disease-free control subjects in the MVP cohort. Correlations of Sloan chart scores with MSFC and Expanded Disability Statue Scale (EDSS) scores in both studies were significant and moderate in magnitude, demonstrating that Sloan chart scores reflect visual and neurologic dysfunction not entirely captured by the EDSS or MSFC.

CONCLUSIONS

Among clinical measures, contrast letter acuity (Sloan charts) and contrast sensitivity (Pelli-Robson chart) demonstrate the greatest capacity to identify binocular visual dysfunction in MS. Sloan chart testing also captures unique aspects of neurologic dysfunction not captured by current EDSS or MSFC components, making it a strong candidate visual function test for the MSFC.

Factorial correspondence analysis of fear-related behaviour traits in Japanese quail

Factorial correspondence analysis was performed on 341 quails from a F2 cross between two lines divergently selected on the duration of tonic immobility over 29 generations. Several fear- or stress-related traits were recorded, i.e. tonic immobility duration, number of inductions needed to induce tonic immobility, open-field behaviour (time spent walking, latency before first movement and number of defecations), asymmetry of tibia lengths and corticosterone concentration after restraint stress. Variables were categorised in classes and analysed by factorial correspondence analysis. The first axis was mostly described by open-field behaviour, and the second by tonic immobility traits (duration of tonic immobility and number of inductions), which showed that these behaviours were almost independent. No relationship was found between axes of the factorial correspondence analysis and corticosterone concentration or asymmetry of tibia lengths, showing that these variables reflected other characteristics of stress susceptibility than those described by tonic immobility and open-field behaviour. These results show that reaction to stress of quails is a multidimensional trait and cannot be summarised by one trait.

Restoring the Mauri of Oruarangi Creek

In recognition of the societal and cultural values of ecological restoration several community-based programs have been developed throughout the world. In particular those with interests in the field of freshwater and riparian management have developed numerous programs to encourage community involvement in their management. While each of these programs gives de facto recognition to an ethos typically espoused by indigenous peoples, the concerns, values and localised knowledge of indigenous peoples continues to remain excluded from the management process. In documenting key aspects of the proposed restoration of Oruarangi Creek this paper aims to provide an example of how the concerns, values and knowledge of local indigenous communities can form a major component of the restoration process.

Differential expression of the actin-binding proteins, alpha-actinin-2 and -3, in different species: implications for the evolution of functional redundancy

The alpha-actinins are a multigene family of four actin-binding proteins related to dystrophin. The two skeletal muscle isoforms of alpha-actinin (ACTN2 and ACTN3) are major structural components of the Z-line involved in anchoring the actin-containing thin filaments. In humans, ACTN2 is expressed in all muscle fibres, while ACTN3 expression is restricted to a subset of type 2 fibres. We have recently demonstrated that alpha-actinin-3 is absent in approximately 18% of individuals in a range of human populations, and that homozygosity for a premature stop codon (577X) accounts for most cases of true alpha-actinin-3 deficiency. Absence of alpha-actinin-3 is not associated with an obvious disease phenotype, raising the possibility that ACTN3 is functionally redundant in humans, and that alpha-actinin-2 is able to compensate for alpha-actinin-3 deficiency. We now present data concerning the expression of ACTN3 in other species. Genotyping of non-human primates indicates that the 577X null mutation has likely arisen in humans. The mouse genome contains four orthologues which all map to evolutionarily conserved syntenic regions for the four human genes. Murine Actn2 and Actn3 are differentially expressed, spatially and temporally, during embryonic development and, in contrast to humans, alpha-actinin-2 expression does not completely overlap alpha-actinin-3 in postnatal skeletal muscle, suggesting independent function. Furthermore, sequence comparison of human, mouse and chicken alpha-actinin genes demonstrates that ACTN3 has been conserved over a long period of evolutionary time, implying a constraint on evolutionary rate imposed by continued function of the gene. These observations provide a real framework in which to test theoretical models of genetic redundancy as they apply to human populations. In addition we highlight the need for caution in making conclusions about gene function from the phenotypic consequences of loss-of-function mutations in animal knockout models.

Epitope mapping of monoclonal antibodies capable of neutralizing cytotoxic necrotizing factor type 1 of uropathogenic Escherichia coli

Cytotoxic necrotizing factor type 1 (CNF1) of uropathogenic Escherichia coli belongs to a family of bacterial toxins that target the small GTP-binding Rho proteins that regulate the actin cytoskeleton. Members of this toxin family typically inactivate Rho; however, CNF1 and the highly related CNF2 activate Rho by deamidation. Other investigators have reported that the first 190 amino acids of CNF1 constitute the cellular binding domain and that the CNF1 enzymatic domain lies within a 300-amino-acid stretch in the C terminus of the toxin. Amino acids 53 to 75 appear to be critical for cell receptor recognition, while amino acids Cys866 and His881 are considered essential for deamidation activity. To delineate further the functional domains of CNF1, we generated 16 monoclonal antibodies (MAbs) against the toxin and used them for epitope mapping studies. Based on Western blot immunoreactivity patterns obtained from a series of truncated CNF1 proteins, this panel of MAbs mapped to epitopes located throughout the toxin, including the binding and enzymatic domains. All MAbs showed reactivity to CNF1 by Western and dot blot analyses. However, only 7 of the 16 MAbs exhibited cross-reactivity with CNF2. Furthermore, only three MAbs demonstrated the capacity to neutralize toxin in either HEp-2 cell assays (inhibition of multinucleation) or 5637 bladder cell assays (inhibition of cytotoxicity). Since CNF1 epitopes recognized by neutralizing MAbs are likely to represent domains or regions necessary for the biological activities of the toxin, the epitopes recognized by these three MAbs, designated JC4 (immunoglobulin G2a [IgG2a]), BF8 (IgA), and NG8 (IgG2a), were more precisely defined. MAbs JC4 and BF8 reacted with epitopes that were common to CNF1 and CNF2 and located within the putative CNF1 binding domain. MAb JC4 recognized an epitope spanning amino acids 169 to 191, whereas MAb BF8 mapped to an epitope between amino acids 135 and 164. Despite the capacity of both MAbs to recognize CNF2 in Western blot analyses, only MAb BF8 neutralized CNF2. MAb NG8 showed reactivity to a CNF1-specific epitope located between amino acids 683 and 730, a region that includes a very small portion of the putative enzymatic domain. Taken together, these findings identify three new regions of the toxin that appear to be critical for the biological activity of CNF1.

Memory for faces, shoes, and objects by deaf and hearing signers and hearing nonsigners

The visual spatial memory of 15 deaf signers, 15 hearing signers, and 15 hearing nonsigners for shoes, faces, and verbalizable objects was measured using the game Concentration. It was hypothesized that the deaf and hearing signers would require fewer attempts than the hearing nonsigners on the shoes and faces tasks because of their experience of using a visual-spatial language; and, in the case of the Deaf, also possibly, due to a compensatory mechanism. It was also hypothesized that memory for shoes would be more like that for faces than for simple objects. It was also anticipated that there would be no difference between the three group's memories for verbalizable objects. Deaf signers were found to be similar to hearing signers, both of whom were better than hearing nonsigners on the faces and shoes tasks. Generally, performance on the faces and shoes tasks was similar and followed the same pattern for the three groups. The three groups performed at a similar level on the objects task. There were no gender differences.

Cancer predisposition caused by elevated mitotic recombination in Bloom mice

Bloom syndrome is a disorder associated with genomic instability that causes affected people to be prone to cancer. Bloom cell lines show increased sister chromatid exchange, yet are proficient in the repair of various DNA lesions. The underlying cause of this disease are mutations in a gene encoding a RECQ DNA helicase. Using embryonic stem cell technology, we have generated viable Bloom mice that are prone to a wide variety of cancers. Cell lines from these mice show elevations in the rates of mitotic recombination. We demonstrate that the increased rate of loss of heterozygosity (LOH) resulting from mitotic recombination in vivo constitutes the underlying mechanism causing tumour susceptibility in these mice.

Cytotoxic necrotizing factor type 1 of uropathogenic Escherichia coli kills cultured human uroepithelial 5637 cells by an apoptotic mechanism

Pathogenic Escherichia coli associated with urinary tract infections (UTIs) in otherwise healthy individuals frequently produce cytotoxic necrotizing factor type 1 (CNF1), a member of the family of bacterial toxins that target the Rho family of small GTP-binding proteins. To gain insight into the function of CNF1 in the development of E. coli-mediated UTIs, we examined the effects of CNF1 intoxication on a panel of human cell lines derived from physiologically relevant sites (bladder, ureters, and kidneys). We identified one uroepithelial cell line that exhibited a distinctly different CNF1 intoxication phenotype from the prototypic one of multinucleation without cell death that is seen when HEp-2 or other epithelial cells are treated with CNF1. The 5637 bladder cell line detached from the growth surface within 72 h of CNF1 intoxication, a finding that suggested frank cytotoxicity. To determine the basis for the unexpected toxic effect of CNF1 on 5637 cells, we compared the degree of toxin binding, actin fiber formation, and Rho modification with those CNF1-induced events in HEp-2 cells. We found no apparent difference in the amount of CNF1 bound to 5637 cells and HEp-2 cells. Moreover, CNF1 modified Rho, in vivo and in vitro, in both cell types. In contrast, one of the classic responses to CNF1 in HEp-2 and other epithelial cell lines, the formation of actin stress fibers, was markedly absent in 5637 cells. Indeed, actin stress fiber induction by CNF1 did not occur in any of the other human bladder cell lines that we tested (J82, SV-HUC-1, or T24). Furthermore, the appearance of lamellipodia and filopodia in 5637 cells suggested that CNF1 activated the Cdc42 and Rac proteins. Finally, apoptosis was observed in CNF1-intoxicated 5637 cells. If our results with 5637 cells reflect the interaction of CNF1 with the transitional uroepithelium in the human bladder, then CNF1 may be involved in the exfoliative process that occurs in that organ after infection with uropathogenic E. coli.

Energetics of strand-displacement reactions in triple helices: a spectroscopic study

DNA triple helices offer exciting new perspectives toward oligonucleotide-directed inhibition of gene expression. Purine and GT triplexes appear to be the most promising motifs for stable binding under physiological conditions compared to the pyrimidine motif, which forms at relatively low pH. There are, however, very little data available for comparison of the relative stabilities of the different classes of triplexes under identical conditions. We, therefore, designed a model system which allowed us to set up a competition between the oligonucleotides of the purine and pyrimidine motifs targeting the same Watson-Crick duplex. Several conclusions may be drawn: (i) a weak hypochromism at 260 nm is associated with purine triplex formation; (ii) delta H degree of GA, GT and TC triplex formation (at pH 7.0) was calculated as -0.1, -2.5 and -6.1 kcal/mol per base triplet, respectively. This unexpectedly low delta H degree for the purine triple helix formation implies that its delta G degree is nearly temperature-independent and it explains why these triplexes may still be observed at high temperatures. In contrast, the pyrimidine triplex is strongly favoured at lower temperatures; (iii) as a consequence, in a system where two third-strands compete for triplex formation, displacement of the GA or GT strand by a pyrimidine strand may be observed at neutral pH upon lowering the temperature. This original purine-to-pyrimidine triplex conversion shows a significant hypochromism at 260 nm and a hyperchromism at 295 nm which is similar to the duplex-to-triplex conversion in the pyrimidine motif. Further evidence for this triplex-to-triplex conversion is provided by mung bean-nuclease foot-printing assay.

Neurobehavioral evidence for working-memory deficits in school-aged children with histories of prematurity

Cognitive performance in 7- to 9-year-old preterm neonatal intensive-care survivors was compared with that in age-matched control children. Non-verbal memory span, spatial working-memory abilities, planning, set-shifting, and recognition memory for both spatial and patterned stimuli were assessed using the Cambridge Neuropsychological Testing Automated Battery. Relative to children in the control group, neonatal intensive-care unit (NICU) survivors demonstrated 25% more memory errors on the spatial working-memory task. Their use of strategy on this task was similar to a control group of 5-year-olds. Planning times on 'Tower of London' problems were long relative to those of term controls. NICU survivors demonstrated poorer pattern recognition as well as a shorter spatial memory span. The groups did not differ in visual-discrimination learning or in spatial-recognition memory. No specific neonatal risk factor accounted for the observed differences, although scores on the Neurobiological Risk Score (NBRS), a composite measure of neonatal risk, did predict several aspects of later task performance. Whether these data reflect a developmental delay in brain maturation in NICU survivors or the presence of a permanent information-processing deficit due to adverse neonatal events must be assessed through continued follow-up.

Prevalence of dysthymic disorder in primary care

BACKGROUND

Dysthymic disorder is characterised as a chronic state of depressed mood which is not otherwise attributable to physical, psychological or social events. While it can occur alone, there is increasing evidence that the majority of individuals who meet criteria for dysthymic disorder also experience more severe episodic mood disorders throughout their lifetime, and there is also an aggregation of mood disorders within their family members. Patients with dysthymic disorder are most often seen in primary care. Some researchers suggest that the majority of these individuals are never diagnosed or are not diagnosed until a more severe episodic mood disorder develops. The objective of this study was to determine the 12-month prevalence of Axis I psychiatric disorders, and in particular dysthymic disorder, in a primary care Health Service Organization in Ontario, Canada.

METHODS

Eligible and consenting adults registered with a primary care Health Service Organization were screened using the modified form of the University of Michigan Composite International Diagnostic Interview.

RESULTS

Of the 6280 eligible subjects, 4327 (69%) consented to screening. Two hundred and twenty-two (5.1%) subjects screened positive for dysthymic disorder. In addition, 90% of those who screened positive for dysthymic disorder also screened positive for other Axis I disorders including major depressive disorder, panic, simple phobia, and generalized anxiety disorder.

CONCLUSIONS

There is much potential for the primary care physician to play a pivotal role in the recognition and treatment of dysthymic disorder and associated Axis I disorders. A focus on the family as a unit for care may be especially important given the reported aggregation of dysthymic disorder within families.

Association between subjective sleep quality and depression on immunocompetence in low-income women at risk for cervical cancer

OBJECTIVE

The purpose of this study was to investigate whether subjective sleep quality is more strongly associated with immunocompetence than depression among women at risk for cervical cancer.

METHODS

Participants were 91 women referred for colposcopy because of abnormal results on a Pap smear. On the day of the procedure. participants completed the Center for Epidemiological Studies Depression Scale, two indices of subjective sleep quality (ie, satisfaction with sleep obtained and degree of sleep restfulness), and a health behaviors assessment questionnaire. Levels of peripheral blood lymphocyte subpopulations (helper T, cytotoxic/suppressor T, NK, and B cells) were also assessed at this time. Approximately 10 days later, the presence of depressive disorder was assessed using the Structured Clinical Interview for DSM-III-R.

RESULTS

Hierarchical regression analyses revealed that satisfaction with the amount of sleep obtained was significantly associated with the circulating number and percentage of helper T cells (T(H)/CD4+) and the percentage of cytotoxic/suppressor T cells (T(C)/CD8+), after controlling for confounder variables (ie, age, smoking status, and drug use). Depression was significantly associated only with the percentage of T(C) cells. Sleep satisfaction remained significantly associated with the number and percentage of T(H) cells and percentage of T(C) cells after controlling for the variance explained by depression.

CONCLUSIONS

Results of this study suggest that subjective sleep quality shares a significant and independent portion of the variance with immunity that is not accounted for by depression. Although the long-term impact of these immune alterations on disease progression needs to be directly explored, it may be important to systematically screen for and manage sleep disturbance in women at high risk for cervical cancer.

Disruption of mRad50 causes embryonic stem cell lethality, abnormal embryonic development, and sensitivity to ionizing radiation

The Mre11/Rad50 protein complex functions in diverse aspects of the cellular response to double-strand breaks (DSBs), including the detection of DNA damage, the activation of cell cycle checkpoints, and DSB repair. Whereas genetic analyses in Saccharomyces cerevisiae have provided insight regarding DSB repair functions of this highly conserved complex, the implication of the human complex in Nijmegen breakage syndrome reveals its role in cell cycle checkpoint functions. We established mRad50 mutant mice to examine the role of the mammalian Mre11/Rad50 protein complex in the DNA damage response. Early embryonic cells deficient in mRad50 are hypersensitive to ionizing radiation, consistent with a role for this complex in the repair of ionizing radiation-induced DSBs. However, the null mrad50 mutation is lethal in cultured embryonic stem cells and in early developing embryos, indicating that the mammalian Mre11/Rad50 protein complex mediates functions in normally growing cells that are essential for viability.

Racial bias in federal nutrition policy, Part II: Weak guidelines take a disproportionate toll

Many diet-related chronic diseases take a disproportionate toll among members of racial minorities. Research shows the prevalence of diabetes, hypertension, cancer, and heart disease is higher among various ethnic groups compared with whites. The Guidelines and the Food Guide Pyramid, however, promote the use of multiple servings of meats and dairy products each day and do not encourage replacing these foods with vegetables, legumes, fruits, and grains. The Dietary Guidelines for Americans encourage a 30% caloric reduction in fat intake and make no provision for further reductions for those who wish to minimize health risks. Abundant evidence has shown that regular exercise combined with diets lower in fat and richer in plant products than is encouraged by the Dietary Guidelines for Americans are associated with reduced risk of these chronic conditions. While ineffective Dietary Guidelines potentially put all Americans at unnecessary risk, this is particularly true for those groups hardest hit by chronic disease.

Racial bias in federal nutrition policy, Part I: The public health implications of variations in lactase persistence

The Dietary Guidelines for Americans from the basis for all federal nutrition programs and incorporate the Food Guide Pyramid, a tool to educate consumers on putting the Guidelines into practice. The Pyramid recommends two to three daily servings of dairy products. However, research has shown that lactase nonpersistence, the loss of enzymes that digest the milk sugar lactose, occurs in a majority of African-, Asian-, Hispanic-, and Native-American individuals. Whites are less likely to develop lactase nonpersistence and less likely to have symptoms when it does occur. Calcium is available in other foods that do not contain lactose. Osteoporosis is less common among African Americans and Mexican Americans than among whites, and there is little evidence that dairy products have an effect on osteoporosis among racial minorities. Evidence suggests that a modification of federal nutrition policies, making dairy-product use optional in light of other calcium sources, may be a helpful public health measure.

Prospective care of elderly patients in family practice. Is screening effective?

OBJECTIVE

To evaluate cost and benefits of screening for and treating health and lifestyle risks among community-dwelling elderly.

DESIGN

Randomized controlled trial.

SETTING

Primary care.

PARTICIPANTS

An opportunistic and prompted sample of 619 rostered elderly patients presenting for treatment who screened positive.

INTERVENTIONS

One third (209) of experimental subjects had screening questionnaires placed in their charts with concerns highlighted for referrals. Two control groups received usual care.

MAIN OUTCOME MEASURES

Yearly assessments of health service use and multidimensional functional capacity.

RESULTS

Overall, screening and treatment of functionally active, elderly, middle-class people had no significant beneficial effect. Almost half of the experimental sample was ineligible because of treatment noncompliance. Generally ineligible subjects were older and more severely impaired. Subjects 75 years and older with risk factors showed improvement in daily living activities, and those living alone were found to have improved mental health and social functions (11% and 22%, respectively).

CONCLUSIONS

Screening and treatment was ineffective in improving total functional capacity of all seniors 65 years and older. Elderly people 75 years and older, however, who were living alone or lonely did benefit from screening and treatment showing an improvement in daily activities, mental health scores, and social functions. This finding has implications for selective preventive health care spending for the elderly. A 2-year follow-up period could be too brief to detect long-term effects of early intervention with younger, middle-class seniors, especially those who are already functionally active.

Structure of the Shigella dysenteriae haem transport locus and its phylogenetic distribution in enteric bacteria

The ability to transport and use haemin as an iron source is frequently observed in clinical isolates of Shigella spp. and pathogenic Escherichia coli. We found that many of these haem-utilizing E. coli strains contain a gene that hybridizes at high stringency to the S. dysenteriae type 1 haem receptor gene, shuA. These shuA-positive strains belong to multiple phylogenetic groups and include clinical isolates from enteric, urinary tract and systemic infections. The distribution of shuA in these strains suggests horizontal transfer of the haem transport locus. Some haem-utilizing pathogenic E. coli strains did not hybridize with shuA, so at least one other haem transport system is present in this group. We also characterized the chromosomal region containing shuA in S. dysenteriae. The shuA gene is present in a discrete locus, designated the haem transport locus, containing eight open reading frames. Several of the proteins encoded in this locus participate with ShuA in haem transport, as a Salmonella typhimurium strain containing the entire haem transport locus used haem much more efficiently than the same strain containing only shuA. The haem transport locus is not present in E. coli K-12 strains, but the sequences flanking the haem transport locus in S. dysenteriae matched those at the 78.7 minute region of E. coli K-12. The junctions and flanking sequences in the shuA-positive pathogenic E. coli strains tested were nearly identical to those in S. dysenteriae, indicating that, in these strains, the haem transport locus has an organization similar to that in S. dysenteriae, and it is located in the same relative position on the chromosome.

Funduscopic lesions associated with mortality in shaken baby syndrome

PURPOSE

The shaken baby syndrome (SBS) has been defined as a syndrome of intraocular and intracranial hemorrhage in young children, thought to be caused by violent shaking inflicted by an adult. In many cases SBS is fatal as a result of intracranial injury. Intraocular findings include hemorrhage, which may be accompanied by characteristic retinal folds or retinoschisis lesions. This study was performed to determine whether acute ophthalmologic findings might predict a fatal outcome.

METHODS

A consecutive series of 10 patients meeting a strict definition of SBS was reviewed for ophthalmic findings at presentation and outcome.

RESULTS

Seven patients survived, and three died. Of the six funduscopic characteristics identified in these patients, two were significantly associated with a fatal outcome: circular perimacular retinal folds found in four patients (p = 0.048) and peripheral retinoschisis lesions seen in three patients (p = 0.012). Lack of visual response at initial examination was also significantly associated with a fatal outcome (p = 0.033).

CONCLUSIONS

Ophthalmic examination of children with suspected SBS is important for prognostic as well as diagnostic purposes. Circular perimacular retinal folds, peripheral retinoschisis lesions, and lack of visual response correlated with fatal neurologic trauma and may be useful in predicting severity of central nervous system injury in shaken baby syndrome.

Identification of shuA, the gene encoding the heme receptor of Shigella dysenteriae, and analysis of invasion and intracellular multiplication of a shuA mutant

shuA encodes a 70-kDa outer membrane heme receptor in Shigella dysenteriae. Analysis of the shuA DNA sequence indicates that this gene encodes a protein with homology to TonB-dependent receptors of gram-negative bacteria. Transport of heme by the ShuA protein requires TonB and its accessory proteins ExbB and ExbD. The shuA DNA sequence contains a putative Fur box overlapping the -10 region of a potential shuA promoter, and the expression of shuA is repressed by exogenous iron or hemin in a Fur-dependent manner, although hemin repressed expression to a lesser extent than iron salts. Disruption of this open reading frame on the S. dysenteriae chromosome by marker exchange yielded a strain that failed to use heme as an iron source, indicating that shuA is essential for heme transport in S. dysenteriae. However, shuA is not essential for invasion or multiplication within cultured Henle cells; the shuA mutant invaded and produced normal plaques in confluent cell monolayers.

Triple helical structures involving inosine: there is a penalty for promiscuity

Inosine has the ability to act as a "wild-card" binding nonspecifically to both A.T and G.C base pairs. This has obvious implications for the design of oligonucleotide site-directed probes. In this paper we present a series of oligonucleotides with a 5'pur9-pyr9-pyr9 motif which are designed to fold up sequentially into intramolecular triple helices. One or more inosines are incorporated into the Hoogsteen strands in place of T's and/or C's. Once folded into the triplex, the inosine-containing third strand is incorporated in parallel orientation to the purine strand of the duplex. The influence of inosine on the triplex-duplex equilibrium, characterized by the melting temperature (Tm) and on the phase boundaries, as a function of pH and/or ionic strength, has been assessed by means of UV and CD spectroscopy. There are two distinguishable influences of third-strand inosines which affect binding, namely, backbone distortion due to bulkiness (I for T and I for C+) and/or loss of intramolecular ion pairs between protonated cytosines and the backbone phosphates (I for C+). A single thymine replacement drops the Tm by 25.0 (+/- 2.1) degrees C, and replacing a single protonated cytosine drops the Tm by 32.1 (+/- 1.0) degrees C at pH 6.0. On introducing two inosines in place of thymines, the Tm at pH 6.0 of the triple helix to hairpin transition is lowered by 35.5 (+/- 1.4) degrees C; on introducing two inosines in place of cytosines, the Tm drops by 44.5 (+/- 1.0) degree C, and on replacing a cytosine and a neighboring thymine with inosines, the Tm of the same transition is lowered by 29.2 (+/- 1.6) degrees C. Replacing more than two thymines or cytosines, respectively, eliminates the binding of the Hoogsteen strand at room temperature altogether. Under no circumstances does inosine replacement stabilize the triplex helix: it is a poor substitute and its role as a wild-card is limited.

Genetics and regulation of heme iron transport in Shigella dysenteriae and detection of an analogous system in Escherichia coli O157:H7

Shigella species can use heme as the sole source of iron. In this work, the heme utilization locus of Shigella dysenteriae was cloned and characterized. A cosmid bank of S. dysenteriae serotype 1 DNA was constructed in an Escherichia coli siderophore synthesis mutant incapable of heme transport. A recombinant clone, pSHU12, carrying the heme utilization system of S. dysenteriae was isolated by screening on iron-poor medium supplemented with hemin. Transposon insertional mutagenesis and subcloning identified the region of DNA in pSHU12 responsible for the phenotype of heme utilization. Minicell analysis indicated that a 70-kDa protein encoded by this region was sufficient to allow heme utilization in E. coli. Synthesis of this protein, designated Shu (Shigella heme uptake), was induced by iron limitation. The 70-kDa protein is located in the outer membrane and binds heme, suggesting it is the S. dysenteriae heme receptor. Heme iron uptake was found to be TonB dependent in E. coli. Transformation of an E. coli hemA mutant with the heme utilization subclone, pSHU262, showed that heme could serve as a source of porphyrin as well as iron, indicating that the entire heme molecule is transported into the bacterial cell. DNA sequences homologous to shu were detected in strains of S. dysenteriae serotype 1 and E. coli O157:H7.

Care of dying patients in hospital

OBJECTIVE

To study the process of care of dying patients in general hospitals.

DESIGN

Non-participant observer (MM) carried out regular periods of continuous comprehensive observation in wards where there were dying patients, recording the quantity and quality of care given. Observations were made in 1983.

SETTING

13 wards (six surgical, six medical, and one specialist unit) in four large teaching hospitals (bed capacity 504-796) in west of Scotland.

SUBJECTS

50 dying patients (29 female, 21 male) with mean age of 66 (range 40-89); 29 were dying from cancer and 21 from non-malignant disease.

RESULTS

Final period of hospitalisation ranged from 6 hours to 24 weeks. More than half of all patients retained consciousness until shortly before death. Basic interventions to maintain patients' comfort were often not provided: oral hygiene was often poor, thirst remained unquenched, and little assistance was given to encourage eating. Contact between nurses and the dying patients was minimal; distancing and isolation of patients by most medical and nursing staff were evident; this isolation increased as death approached.

CONCLUSIONS

Care of many of the dying patients observed in these hospitals was poor. We need to identify and implement practical steps to facilitate high quality care of the dying. Much can be learned from the hospice movement, but such knowledge and skills must be replicated in all settings.

Do Hydrofluorocarbons Destroy Stratospheric Ozone?

Hydrofluorocarbons, many of which contain a CF(3) group, are one of the major substitutes for the chlorofluorocarbons and halons that are being phased out because they contribute to stratospheric ozone depletion. It is critical to ensure that CF(3) groups do not cause significant ozone depletion. The rate coefficients for the key reactions that determine the efficiency of the CF(3) radical as a catalyst for ozone loss in the stratosphere have been measured and used in a model to calculate the possible depletion of ozone. From these results, it is concluded that the ozone depletion potentials related to the presence of the CF(3) group in hydrofluorocarbons are negligibly small.