The respiratory enzyme complex Rnf is vital for metabolic adaptation and virulence in Fusobacterium nucleatum

IMPORTANCE

This paper illuminates the significant question of how the oral commensal Fusobacterium nucleatum adapts to the metabolically changing environments of several extra-oral sites such as placenta and colon to promote various diseases as an opportunistic pathogen. We demonstrate here that the highly conserved Rhodobacter nitrogen-fixation complex, commonly known as Rnf complex, is key to fusobacterial metabolic adaptation and virulence. Genetic disruption of this Rnf complex causes global defects in polymicrobial interaction, biofilm formation, cell growth and morphology, hydrogen sulfide production, and ATP synthesis. Targeted metabolomic profiling demonstrates that the loss of this respiratory enzyme significantly diminishes catabolism of numerous amino acids, which negatively impacts fusobacterial virulence as tested in a preterm birth model in mice.

The respiratory enzyme complex Rnf is vital for metabolic adaptation and virulence in Fusobacterium nucleatum

A prominent oral commensal and opportunistic pathogen, Fusobacterium nucleatum can traverse to extra-oral sites such as placenta and colon, promoting adverse pregnancy outcomes and colorectal cancer, respectively. How this anaerobe sustains many metabolically changing environments enabling its virulence potential remains unclear. Informed by our genome-wide transposon mutagenesis, we report here that the highly conserved Rnf complex, encoded by the rnfCDGEAB gene cluster, is key to fusobacterial metabolic adaptation and virulence. Genetic disruption of the Rnf complex via non-polar, in-frame deletion of rnfC (Δ rnfC ) abrogates polymicrobial interaction (or coaggregation) associated with adhesin RadD and biofilm formation. The defect in coaggregation is not due to reduced cell surface of RadD, but rather an increased level of extracellular lysine, which binds RadD and inhibits coaggregation. Indeed, removal of extracellular lysine via washing Δ rnfC cells restores coaggregation, while addition of lysine inhibits this process. These phenotypes mirror that of a mutant (Δ kamAΔ ) that fails to metabolize extracellular lysine. Strikingly, the Δ rnfC mutant is defective in ATP production, cell growth, cell morphology, and expression of the enzyme MegL that produces hydrogen sulfide from cysteine. Targeted metabolic profiling demonstrated that catabolism of many amino acids, including histidine and lysine, is altered in Δ rnfC cells, thereby reducing production of ATP and metabolites including H2S and butyrate. Most importantly, we show that the Δ rnfC mutant is severely attenuated in a mouse model of preterm birth. The indispensable function of Rnf complex in fusobacterial pathogenesis via modulation of bacterial metabolism makes it an attractive target for developing therapeutic intervention.

Methamphetamine and cardiac disease among people with HIV infection

OBJECTIVES

People living with HIV (PWH) are at elevated risk of cardiac disease compared to the general population. Methamphetamine use has been associated with structural heart disease and increased mortality from cardiovascular disease but has not been explored as a cause of cardiac disease among PWH. We sought to evaluate the association of methamphetamine use and cardiac disease among PWH.

METHODS

We performed a case-control study of participant data in the HIV Neurobehavioral Research Program. Cases were defined as PWH with a history of myocardial infarction or a history of heart failure (systolic or diastolic). Covariates, including methamphetamine abuse/dependence, were assessed using multiple logistic regression.

RESULTS

Among 3747 PWH, there was a history of myocardial infarction in 115 subjects (3.1%), and a history of heart failure in 41 (1.1%). Current or prior methamphetamine abuse/dependence was reported in 1036 (27.9%) and was not associated with myocardial infarction (P = 0.27) or heart failure (P = 0.84). In addition to traditional risk factors, variables associated with myocardial infarction included the presence of HIV infection (P = 0.01) and duration of HIV infection (P = 0.05). Variables associated with heart failure among PWH included older age, hypertension and myocardial infarction.

CONCLUSIONS

No association between methamphetamine abuse/dependence and a diagnosis of myocardial infarction or heart failure was found among PWH. Significant covariates for myocardial infarction and heart failure included traditional risk factors, the presence of HIV infection and the duration of HIV infection, emphasizing the need for optimal traditional cardiovascular risk factor management among PWH.

A-06 Current Norms May Overestimate Rates of Neurocognitive Impairment among American Indian and Alaskan Native Adults

Objective

Currently available normative data subsume American Indian and Alaskan Native (AI/AN) populations within the non-Latinx white (NLW) ethnoracial group. The classification accuracy of such norms among AI/AN remains unknown. This cross-sectional study aims to identify whether disparities exist in the rates of neurocognitive impairment (NCI) between AI/AN and NLW adults. < br><br > 

Method

Two hundred community-dwelling adults (50% NLW; 50% Male; M Age = 42 ± 14 years; M Education = 13 ± 3 years) completed comprehensive neurocognitive, quality of education (Wide Range Achievement Test- 4 [WRAT-4]), neuromedical, urine toxicology, and psychiatric/substance use evaluations. Average T-scores were calculated using widely used demographically corrected (age, gender, education) NLW norms to identify NCI (> 1 SD; e.g., Heaton et al., 2004; Heaton & Marcotte, 2000). A comorbid condition propensity score (CCPS) identified the probability to which comorbid conditions (e.g., Heaton et al., 2010) informed ethnoracial identity. <br><br > 

Results

After adjusting for WRAT-4 and CCPS, the results of a logistic regression analysis demonstrated a significant ethnoracial disparity in risk for NCI (X2(3) = 13.88, p<.01, R2 = .07), such that the AI/AN group was at 2.52 times higher odds (32.3% vs. 16.0, CI: 1.15–5.46, p = .01, Cohen’s d = .51) for NCI in comparison to the NLW group. <br><br > 

Conclusions

Published norms for NLW adults may overestimate impairment in AI/AN adults. Thus, population-specific normative data are needed to clarify the classification accuracy of neurocognitive impairment and possible disparities in neurocognitive disorders (e.g., HIV-associated neurocognitive disorders) among AI/AN adults. Future work should replicate these findings among other diverse populations (e.g., Caribbean, Middle Eastern) lacking population-specific normative data.876199.

Demographically-Corrected Norms for the Grooved Pegboard Test and Finger Tapping Test in monolingual Spanish speakers from the U.S.-Mexico Border Region

Objective

We developed demographically-corrected norms for US-dwelling, Spanish-speaking Hispanics on two widely used tests of motor skills - the Grooved Pegboard Test (Pegs) and Finger Tapping Test (Tapping). We then examined the effects of applying established norms for non-Hispanic Caucasians (NH Whites) and non-Hispanic African Americans (NH Blacks) on motor test results from our Hispanic population.

Participants and Method

254 participants living in the US-Mexico border region of San Diego, CA and Tucson, AZ completed Pegs, and a subset (n = 183) completed Tapping. Age ranged from 19-60 and education from 0-20 years, with 59% women. Raw test scores were converted to demographically-corrected T-scores with a fractional polynomial procedure and compared to a fitted curve for the original data.

Results

Findings included significant main effects of education on both tests (p < .001), and of age for Pegs (p < .001). There was a significant interaction of sex and age on Tapping, such that older age was associated with lower scores in men only (p = .02). The resulting normative T-scores were confirmed to be free from demographic influences. Using a T < 40 cut point, rates of impairment in the Spanish speaking normative sample for dominant (D) and nondominant (ND) hands, respectively, were 17% and 14% for Pegs, and 12% and 10% for Tapping. Applying existing norms for NH Whites and NH Blacks to the raw scores of Spanish speakers generally yielded lower impairment rates on all measures, with one exception, Pegs ND, for which NH White norms overestimated impairment (23%).

Conclusions

Normative standards from other groups are not a good fit for interpreting motor test performance in this Hispanic population, which in the current instance would have generally underdiagnosed fine motor impairment. These findings underscore the importance of appropriate, population-specific normative data- even for tests of motor ability.

Comparison of Rates of Impairment Between Three Sets of Normative Data for Spanish-speakers of Mexican Origin in a Healthy Cohort

Objective

With over 37 million Spanish-speakers, the US is the second country in the world with the largest number of Spanish-speakers. Identification of neurological dysfunction via neuropsychological testing for this language group requires knowledgeable application of available tests and normative data. Accordingly, we investigated whether rates of neurocognitive impairment (NCI) varied based on the Spanish language normative method used.

Method

Participants included 254 healthy native Spanish-speakers (Age: M = 37.3, SD = 10.4; Education: M = 10.7, SD = 4.3; 59% Female; 78.7% of known Mexican origin/descent) living in the US-Mexico border region. Participants completed the Hopkins Verbal Learning Test-Revised (HVLT-R), Trail Making Test (TMT) A&B, and Animal Naming in Spanish. Raw test scores were converted to demographically-adjusted T-scores based on normative adjustments developed for this population (Neuropsychological Norms for the US-Mexico Border Region in Spanish [NP-NUMBRS]) and norms developed based on samples in Mexico (Latin American Norms from Mexico [LAN-M] and NEUROPSI). Rates of NCI (T < 40) based on the different normative methods were compared via McNemar’s tests.

Results

Rates of NCI for NP-NUMBRS and NEUROPSI fell between the expected 15-17%. Compared to NP-NUMBRS, significantly lower rates were found when applying LAN-M for HVLT-R Total (4%) and Delayed Recall (8%), TMT-A (1%), and Animal Naming (10%; all ps < .0002). No significant differences were found for TMT-B (p > .05).

Conclusions

Present findings revealed that while the NP-NUMBRS and NEUROPSI norms yielded similar NCI rates, and LAN-M norms underestimated NCI on three tests. This highlights the importance of carefully considering available normative adjustments for Spanish-speakers when applying them to specific populations.

Controlling alcohol availability through local policy: an observational study to evaluate Cumulative Impact Zones in a London borough

Background

Cumulative impact zones (CIZs) are a discretionary policy lever available to local government, used to restrict the availability of alcohol in areas deemed already saturated. Despite little evidence of their effect, over 200 such zones have been introduced. This study explores the impact of three CIZs on the licensing of venues in the London Borough of Southwark.

Methods

Using 10 years of licensing data, we examined changes in the issuing of licences on the introduction of three CIZs within Southwark, relative to control areas. The number of licence applications made (N = 1110), the number issued, and the proportion objected to, were analysed using negative binomial regression.

Results

In one area tested, CIZ implementation was associated with 119% more licence applications than control areas (incidence rate ratios (IRR) = 2.19, 95% confidence intervals (CI): 1.29-3.73, P = 0.004) and 133% more licences granted (IRR = 2.33, 95% CI: 1.31-4.16, P = 0.004). No significant effect was found for the other two areas. CIZs were found to have no discernible effect on the relative proportion of licence applications receiving objections.

Conclusions

CIZs are proposed as a key lever to limit alcohol availability in areas of high outlet density. We found no evidence that CIZ establishment reduced the number of successful applications in Southwark.

Disparities in HIV Viral Load Suppression by Race/Ethnicity Among Men Who Have Sex with Men in the HIV Outpatient Study

Maximizing the rates of virologic suppression (VS) among gay, bisexual, and other men who have sex with men (MSM) is essential to limiting HIV morbidity and sexual transmission of HIV in the United States. We analyzed data for MSM of non-Hispanic white (white), non-Hispanic black (black), or Hispanic/Latino race/ethnicity in the HIV Outpatient Study (HOPS) at nine U.S. HIV clinics. VS (HIV RNA <50 copies/ml) was measured closest to January 1, 2015. We modeled factors associated with VS among persons prescribed antiretroviral therapy (ART) for ≥6 months and assessed VS for a subset of participants with behavioral interview data. Among 1,303 MSM studied, 24% were black and 11% were Hispanic/Latino. Fewer black than white or Hispanic/Latino MSM had any documented ART use history (92% vs. 99% and 94%, respectively), and fewer had VS (72% vs. 91% and 81%), p < .001. In analyses of MSM prescribed ART, which adjusted for insurance type, duration of ART use, and CD4⁺ cell count, blacks had lower prevalence of VS than whites [adjusted prevalence ratio (PR) 0.87, confidence interval (95% CI) 0.81-0.93] and Hispanics/Latinos did not (PR 0.95, 95% CI 0.88-1.02). Among 331 MSM with interview data, 6% had no VS, but reported anal sex without a condom with an HIV-uninfected or unknown HIV serostatus male partner in the past 6 months. In this study of HIV-infected MSM, blacks had a significantly lower prevalence of VS than white men. Optimizing HIV care and prevention among all MSM will require addressing underlying risk factors and social determinants of health that contribute to racial/ethnic disparities in HIV outcomes.

The impact of ethnicity/race on the association between the Veterans Aging Cohort Study (VACS) Index and neurocognitive function among HIV-infected persons

The Veterans Aging Cohort Study (VACS) Index was developed as a risk index for health outcomes in HIV, and it has been consistently associated with mortality. It shows a significant, yet relatively weak, association with neurocognitive impairment, and little is known about its utility among ethnic/racial minority groups. We examined whether the association between the VACS Index and neurocognition differed by ethnic/racial group. Participants included 674 HIV-infected individuals (369 non-Hispanic whites, 111 non-Hispanic blacks, and 194 Hispanics). Neurocognitive function was assessed via a comprehensive battery. Scaled scores for each neurocognitive test were averaged to calculate domain and global neurocognitive scores. Models adjusting for demographics and HIV disease characteristics not included in the VACS Index showed that higher VACS Index scores (indicating poorer health) were significantly associated with worse global neurocognition among non-Hispanic whites. This association was comparable in non-Hispanic blacks, but nonsignificant among Hispanics (with similar results for English and Spanish speaking). We obtained comparable findings in analyses adjusting for other covariates (psychiatric and medical comorbidities and lifestyle factors). Analyses of individual neurocognitive domains showed similar results in learning and delayed recall. For other domains, there was an effect of the VACS Index and no significant interactions with race/ethnicity. Different components of the VACS Index were associated with global neurocognition by race/ethnicity. In conclusion, the association between the VACS Index and neurocognitive function differs by ethnic/racial group. Identifying key indicators of HIV-associated neurocognitive impairment by ethnic/racial group might play an important role in furthering our understanding of the biomarkers of neuroAIDS.

A Matter of Perspective: Comparison of the Characteristics of Persons with HIV Infection in the United States from the HIV Outpatient Study, Medical Monitoring Project, and National HIV Surveillance System

Comparative analyses of the characteristics of persons living with HIV infection (PLWH) in the United States (US) captured in surveillance and other observational databases are few. To explore potential joint data use to guide HIV treatment and prevention in the US, we examined three CDC-funded data sources in 2012: the HIV Outpatient Study (HOPS), a multisite longitudinal cohort; the Medical Monitoring Project (MMP), a probability sample of PLWH receiving medical care; and the National HIV Surveillance System (NHSS), a surveillance system of all PLWH. Overall, data from 1,697 HOPS, 4,901 MMP, and 865,102 NHSS PLWH were analyzed. Compared with the MMP population, HOPS participants were more likely to be older, non-Hispanic/Latino white, not using injection drugs, insured, diagnosed with HIV before 2009, prescribed antiretroviral therapy, and to have most recent CD4+ T-lymphocyte cell count ≥500 cells/mm3 and most recent viral load test<2 00 copies/mL. The MMP population was demographically similar to all PLWH in NHSS, except it tended to be slightly older, HIV diagnosed more recently, and to have AIDS. Our comparative results provide an essential first step for combined epidemiologic data analyses to inform HIV care and prevention for PLWH in the US.

Macroscopic and microscopic changes in incinerated deciduous teeth

Teeth are amongst the most resilient elements of the human skeleton and are thus often utilized in routine forensic investigation involving the identification of unknown remains. Teeth exposed to thermal stress have the potential to not only aid in identification, but also in understanding the circumstances surrounding the fire. Children are twice as likely to become victims of house fire because of an inability to safely evacuate from areas of danger. The literature demonstrates, however, that research on the effects of incineration on teeth is mostly restricted to the permanent dentition. The apparent lack of knowledge on the effects of incineration on deciduous teeth thus necessitates further research in this area. To this end, this study aimed to relate colour changes that occur post heating with fragility to aid in proper handling of samples in a forensic scenario and to determine the possibility of identifying incineration temperature based on tooth condition. Teeth are amongst the most resilient elements of the human skeleton and are thus often utilized in routine forensic investigation involving the identification of unknown remains. Teeth exposed to thermal stress have the potential to not only aid in identification, but also in understanding the circumstances surrounding the fire. Children are twice as likely to become victims of house fire because of an inability to safely evacuate from areas of danger. The literature demonstrates, however, that research on the effects of incineration on teeth is mostly restricted to the permanent dentition. The apparent lack of knowledge on the effects of incineration on deciduous teeth thus necessitates further research in this area. To this end, this study aimed to relate colour changes that occur post heating with fragility to aid in proper handling of samples in a forensic scenario and to determine the possibility of identifying incineration temperature based on tooth condition. A total of 90 deciduous teeth, extracted as a part of routine clinical treatment, were exposed to temperatures ranging from 100°C to 1100°C for 30 minutes using a laboratory Gallenkamp oven. Unheated deciduous teeth were used as controls for the project. Post-incineration the teeth were analyzed under a stereomicroscope and SEM to assess the morphological changes. A colorimetric assessment was also undertaken to evaluate colour changes due to thermal stress. It was possible to identify incineration temperature based on tooth condition when the colour changes, stereomicroscopic findings and SEM images were utilized collectively. It was concluded that thermally induced changes in primary teeth occur at lower temperatures in comparison to the permanent teeth. It was also established that post-incineration deciduous teeth are fragile and show a tendency to fragment after minimal exposure to thermal stress.

Ghosts of the past I: some muscles and fasciae in the head domain

Humans alone among primates lack a superficial head of the temporalis muscle, although a complete superficial muscle is present in 1% of humans and an incomplete one in 8%. Yet the temporal fascia of normal humans contains all the fascial sheets associated with that head even though it is absent. The implication is that humans have lost the superficial temporal muscle, that this is evident from the retention of the fascial sheets, and that the muscular variations represent situations where the muscle has persisted to some degree. Molecular factors in the head domain that are responsible for the development of the muscles of mastication (myosin heavy chain 16) are likewise different in humans than in all non-human species and seem to be responsible for the reduction of those muscles in humans. Could the loss of the superficial portion of the temporalis muscle be a component of this reduction? Could the uncommon muscular variations result from some slight persistence of the prior molecular situation? Could the persistence of the fascial sheets, even when the muscle is absent, be because the molecular factors responsible for connective tissues are not the same as those responsible for muscles? How much of all this can be visualised in the fossil record? Skeletal dimensions of the temporal fossa, partly related to the temporal muscle size, imply that it may be possible to determine in which fossils temporal muscle reduction has occurred. Likewise, surface features of the bone in modern humans without a superficial muscular component but with a strong complex fibrous element suggest that it might be possible to determine, in any fossil in which the surface preservation is good enough, how far back this situation may have persisted. It is already known that myosin heavy chain molecular dating suggests that the muscle reduction may have occurred about 2.4 million years ago.

Ghosts of the past II: muscles and fasciae in the primate forelimb domain

Many forelimb muscles (e.g. coracobrachialis, rhomboids, serratus sheet) are much less complex and much smaller in humans than in other primates. Yet human muscular variations and persistent fascial sheets indicate that increased size and complexity were once the norm. These muscular reductions are associated with equivalent skeletal gracilisation. Is it possible that molecular phenomena, not unlike those producing reduction of the jaw muscles and associated with gracilisation of the skull in species with reduced need for powerful mastication, may also have reduced forelimb muscles with gracilisation of its skeleton in species no longer using a forelimb for powerful locomotion? Could such molecular and skeletal changes be dated (as for the masticatory muscles) thus giving the time of origination of prehuman forelimb reduction and true bipedalism?

Nitrogen and phosphorus runoff losses from variable and constant intensity rainfall simulations on loamy sand under conventional and strip tillage systems

Further studies on the quality of runoff from tillage and cropping systems in the southeastern USA are needed to refine current risk assessment tools for nutrient contamination. Our objective was to quantify and compare effects of constant (Ic) and variable (Iv) rainfall intensity patterns on inorganic nitrogen (N) and phosphorus (P) losses from a Tifton loamy sand (Plinthic Kandiudult) cropped to cotton (Gossypium hirsutum L.) and managed under conventional (CT) or strip-till (ST) systems. We simulated rainfall at a constant intensity and a variable intensity pattern (57 mm h(-1)) and collected runoff continuously at 5-min intervals for 70 min. For cumulative runoff at 50 min, the Iv pattern lost significantly greater amounts (p < 0.05) of total Kjeldahl N (TKN) and P (TKP) (849 g N ha(-1) and 266 g P ha(-1) for Iv; 623 g N ha(-1) and 192 g P ha(-1) for Ic) than did the Ic pattern. However, at 70 min, no significant differences in total losses were evident for TKN or TKP from either rainfall intensity pattern. In contrast, total cumulative losses of dissolved reactive P (DRP) and NO3-N were greatest for ST-Ic, followed by ST-Iv, CT-Ic, and CT-Iv in diminishing order (69 g DRP ha(-1) and 361 g NO3-N ha(-1); 37 g DRP ha(-1) and 133 g NO3-N ha(-1); 3 g DRP ha(-1) and 58 g NO3-N ha(-1); 1 g DRP ha(-1) and 49 g NO3-N ha(-1)). Results indicate that constant-rate rainfall simulations may overestimate the amount of dissolved nutrients lost to the environment in overland flow from cropping systems in loamy sand soils. We also found that CT treatments lost significantly greater amounts of TKN and TKP than ST treatments and in contrast, ST treatments lost significantly greater amounts of DRP and NO3-N than CT treatments. These results indicate that ST systems may be losing more soluble fractions than CT systems, but only a fraction the total N (33%) and total P (11%) lost through overland flow from CT systems.

Geometric morphometric study of population variation in indigenous southern African crania

Much of our understanding of population variation in southern Africa is derived from traditional morphometric research. In the search for new perspectives, this paper reports on new geometric morphometric data examining cranial variation in 12 modern human populations from southern Africa. In total, 298 male Bantu-speaking individuals were studied. In addition, a small Khoisan (Khoikhoi and San) series was also examined. The purpose of this study was to investigate Khoisan-Bantu morphological similarities and differences, and to examine variation within both the Bantu-speaking and Khoisan populations. The three-dimensional coordinates of 96 landmarks were analyzed, using the shape-analysis software morphologika. Interpopulation variation was examined by calculating Procrustes distances between groups; a cluster analysis was then used to summarize phenetic relationships. A principal components analysis explored the relationships between populations; shape differences were visualized and explored using three-dimensional rendered models, and further interpreted using thin-plate splines. Morphological differences are present within and between the crania of Bantu-speaking and Khoisan individuals. The Khoisan demonstrate features (e.g., a pentagonoid vault, more rounded forehead contour, and a small and less prognathic face) that clearly distinguish them from Bantu-speaking populations. Although southern African Bantu-speaking populations are clearly closely related, they show population-specific features (e.g., the crania of more southerly populations (Xhosa, Southern Sotho, and Zulu) are characteristically more brachycephalic and less prognathic). This study suggests that differential admixture with adjacent Khoisan peoples has contributed to diversity within southern African Bantu-speaking populations.

Sexual dimorphism and discriminant function sexing in indigenous South African crania

This study aimed to examine sexual dimorphism in, and to produce a practical discriminant function for determining the sex of indigenous, Bantu-speaking, South African crania. The types of data to be used were a small number of traditional, or mathematically transformed three-dimensional, linear measurements, comparable to those in use by most physical and forensic anthropologists. The samples to be examined, separately and pooled, were of the Cape Nguni, Natal Nguni and Sotho subgroups. In addition, three local populations ('tribes'--Zulu, Xhosa and Southern Sotho) within these subgroups were also studied. Univariate male/female ratios indicate significant sexual dimorphism in the pooled South African crania. Canonical variates analysis of the pooled sample showed that facial width is the strongest discriminating morphometric variable; cranial length and basi-bregmatic height are the next most significant features. Eight measurements derived from the three-dimensional data were used to produce a series of discriminant functions for sex determination in the pooled sample, for which an accuracy of 77-80% was attained. Analysis of the calvaria and face, separately, has shown that the sex of damaged material can be diagnosed with a reasonable degree of accuracy (75-76%). The new functions for the pooled indigenous South African sample provide improved sex discrimination accuracy compared to those obtained by employing the commonly utilised statistics of Giles & Elliot (1963), even when a modified sectioning point is used. Functions calculated for the separate local populations gave variable and fairly low improvements in sexing accuracy. As the subdivisions at all levels are at present quite rapidly disappearing in South Africa, for most purposes it is now best to simply apply the pooled data functions for sexing crania.

Functional analysis of the early chlorosis factor gene

Chlorosis is one of the symptoms of bacterial spot disease caused by Xanthomonas campestris pv. vesicatoria, which induces chlorosis before any other symptoms appear on tomato. We report characterization of a 2.1-kb gene called early chlorosis factor (ecf). The gene ecf encodes a hydrophobic protein with similarity to four other proteins in plant pathogens, including HolPsyAE, and uncharacterized gene products from X. campestris pv. campestris and X. axonopodis pv. citri, and, at the tertiary structure level, to colicin Ia from Escherichia coli. We demonstrate that the associated phenotype is hrp dependent, and that the ecf gene product appears to be translocated to host cells. The gene ecf has no impact on electrolyte leakage or on bacterial growth in planta in response to infection. Concentrated culture filtrates do not produce chlorosis. Study of its role in Xanthomonas spp.-tomato interactions will forward our understanding of symptom production by plant pathogens and allows further investigation into the mechanisms of bacterial virulence and production of symptoms.

Three-dimensional technology for linear morphological studies: a re-examination of cranial variation in four southern African indigenous populations

In order to compare linear dimensions made by traditional anthropometric techniques, and those obtained from three-dimensional coordinates, samples of four indigenous southern African populations were analysed. Linear measurements were obtained using mathematically transformed, three-dimensional landmark data on 207 male crania of Cape Nguni, Natal Nguni, Sotho and Shangaan. Univariate comparisons for accuracy of the transformed linear data were made with those in a traditional linear study by de Villiers (The Skull of the South African Negro: A Biometrical and Morphological Study. Witwatersrand University Press, Johannesburg) on similar samples and equivalent landmarks. Comparisons were not made with her Penrose (Ann Eugenics 18 (1954) 337) analysis as an apparently anomalous 'shape'-'size' statistic was found. The univariate comparisons demonstrated that accurate linear measurements could be derived from three-dimensional data, showing that it is possible to simultaneously obtain data for three-dimensional geometric 'shape' and linear interlandmark analyses. Using Penrose and canonical variates analyses of the transformed three-dimensional interlandmark measurements, similar population distances were found for the four indigenous southern African populations. The inter-population distance relationships took the form of three separated pairs of distances, with the within-pair distances very similar in size. The cranial features of the four populations were found to be overall very similar morphometrically. However the populations were each shown by CVA to have population specific features, and using discriminant analyses 50% or more of the individual crania (with the exception of the Sotho) could be referred to their correct populations.

Variations in expression of oral-facial-digital syndrome (type I): report of two cases

Two case reports are presented, both clearly demonstrating the diagnosis of oral-facial-digital syndrome, type I, but widely different in the expression of the condition. The first patient showed only mild expression of the syndrome. On examination at the age of 4 years there were no obvious extra oral signs, intraoral findings included the presence of supernumeraries in the primary dentition, spacing in two areas and the presence of an extra frenum. The second can be considered as a more severe case. This patient had many of the typical manifestations, including frontal bossing, a degree of zygomatic hypoplasia and clinodactyly. Orally, the most striking finding was a bilateral cleft palate which had not been diagnosed prior to examination at the age of 6 years. Other findings included multiple frena and a bifid tongue.

Extracellular matrix mineralization and osteoblast gene expression by human adipose tissue-derived stromal cells

Human adipose tissue represents an abundant reservoir of stromal cells with potential utility for tissue engineering. The current study demonstrates the ability of human adipose tissue-derived stromal cells to display some of the hallmarks of osteoblast differentiation in vitro. Following treatment with ascorbate, beta-glycerophosphate, dexamethasone, and 1,25 dihydroxy vitamin D(3), adipose tissue-derived stromal cells mineralize their extracellular matrix based on detection of calcium phosphate deposits using Alizarin Red and von Kossa histochemical stains. Fourier transform infrared analysis demonstrates the apatitic nature of these crystals. Mineralization is accompanied by increased expression or activity of the osteoblast-associated proteins osteocalcin and alkaline phosphatase. These and other osteoblast-associated gene markers are detected based on polymerase chain reaction. In contrast, the adipocyte gene markers--leptin, lipoprotein lipase, and peroxisome proliferator activated receptor gamma2--are reduced under mineralization conditions, consistent with the reciprocal relationship postulated to exist between adipocytes and osteoblasts. The current work supports the presence of a multipotent stromal cell population within human extramedullary adipose tissue. These findings have potential implications for human bone tissue bioengineering.

Atypical presentation of tuberculosis meningitis: a case report

A 19 year old woman presented with atypical symptoms of tuberculous meningitis. Meningitis is the most serious form of tuberculosis (TB) and it often presents with nonspecific signs and symptoms. Delayed diagnosis can result in rapid progression of neurological deficits and poor prognosis. Polymerase chain reaction and other nucleic acid amplification methods are becoming increasingly useful for the rapid detection of Mycobacterium tuberculosis in the cerebrospinal fluid. Early treatment reduces morbidity and mortality of this serious condition.

Circuit party attendance, club drug use, and unsafe sex in gay men

PURPOSE

We examined the population demographics and club drugs used in gay circuit parties and estimated the reported unsafe sexual behavior associated with each drug, the reasons for attending circuit parties, and the unsafe sex associated with different reasons.

METHODS

A brief questionnaire was provided to a nonrandom sample of party attendees covering demographics, drugs used, sexual activity, and reasons for attending gay circuit parties at three major North American parties in 1998-1999. A total of 1169 usable questionnaires were obtained. Odds ratios for unsafe sex for the drugs surveyed [alcohol, marijuana, methylenedioxymethamphetamine (Ecstasy), ketamine (Special K), crystal methamphetamine (crystal meth), cocaine, volatile nitrites (poppers), and gamma-hydroxybutyrate (GHB)] were calculated, as was significance of unsafe sex for the 10 major reasons for attending parties.

RESULTS

12-month party drug use was high: > 50% reported using alcohol, Ecstasy, and Special K. Frequent (rather than occasional) use of Ecstasy, Special K, and poppers had an association with unsafe sex at parties. Poppers also showed a statistically significant association with unsafe sex in 12 months (not necessarily at parties) while crystal meth and GHB showed a trend. Attending circuit parties "to look and feel good," "to have sex," and "to be uninhibited and wild" were associated with higher levels of unsafe sex in 12 months.

IMPLICATIONS

In this sample, circuit party attendees are well educated and financially secure. Party drug use is high. It appears that use of poppers, Ecstasy, Special K, crystal meth, and GHB are associated with various measures of unsafe sex. More comprehensive research on club drug use in gay men is required.

Extracellular matrix mineralization and osteoblast gene expression by human adipose tissue-derived stromal cells

Human adipose tissue represents an abundant reservoir of stromal cells with potential utility for tissue engineering. The current study demonstrates the ability of human adipose tissue-derived stromal cells to display some of the hallmarks of osteoblast differentiation in vitro. Following treatment with ascorbate, beta-glycerophosphate, dexamethasone, and 1,25 dihydroxy vitamin D(3), adipose tissue-derived stromal cells mineralize their extracellular matrix based on detection of calcium phosphate deposits using Alizarin Red and von Kossa histochemical stains. Fourier transform infrared analysis demonstrates the apatitic nature of these crystals. Mineralization is accompanied by increased expression or activity of the osteoblast-associated proteins osteocalcin and alkaline phosphatase. These and other osteoblast-associated gene markers are detected based on polymerase chain reaction. In contrast, the adipocyte gene markers--leptin, lipoprotein lipase, and peroxisome proliferator activated receptor gamma2--are reduced under mineralization conditions, consistent with the reciprocal relationship postulated to exist between adipocytes and osteoblasts. The current work supports the presence of a multipotent stromal cell population within human extramedullary adipose tissue. These findings have potential implications for human bone tissue bioengineering.

Persuading the persuadable: evaluating compulsory treatment in England using Supervised Discharge Orders

BACKGROUND

Supervised Discharge Orders (SDOs) were introduced in 1995, as an amendment to the Mental Health Act in England and Wales. They require patients to abide by specific conditions on discharge from hospital, but can not enforce medication compliance. On introduction, SDOs were received with scepticism by the psychiatric profession. The purpose of this study was to describe the use of SDOs in England and the characteristics of patients made subject to these orders, and to evaluate the effectiveness of the order in securing treatment compliance on discharge from hospital.

METHOD

A survey was conducted of 170 mental health provider Trusts in England. Interviews with senior managers in 12 Trusts and associated Local Authorities were subjected to qualitative analysis, and a cohort of patients subject to SDOs in 56 randomly sampled Trusts was described.

RESULTS

SDOs were being used for 596 patients (1.2 per 100,000 total population) at the survey date in 1999, and use had been increasing steadily since its introduction. The order is not systematically considered for all potential cases. The majority of the 182 patients in the cohort had complied, if sometimes intermittently, with conditions of the order.

CONCLUSIONS

For patients compliant with SDOs, the pressures necessary to treat effectively need not involve powers to enforce medication compliance.

Differential expression of signal transducers and activators of transcription during human adipogenesis

Signal Transducers and Activators of Transcription (STATs) display unique expression patterns upon induction of differentiation of murine 3T3-L1 preadipocytes into adipocytes. During differentiation, expression of STAT1 and STAT5 increase, while STAT3 and STAT6 remain relatively unchanged. Here, we determined whether human subcutaneous preadipocytes expressed STATs and if the pattern of expression changed during adipogenesis. We found by Western blot analysis that freshly isolated preadipocytes expressed STAT1, STAT3, STAT5, and STAT6, but not STAT2 and STAT4. Induction of preadipocyte differentiation with 1-methyl-3-isobutylxanthine, dexamethasone, insulin, and BRL49653 decreased expression of STAT1, and increased expression of STAT3 and STAT5. STAT6 expression did not change during adipogenesis. Changes in expression of CCAAT/enhancer binding protein beta (C/EBPbeta), C/EBPdelta, C/EBPalpha, and peroxisome proliferator-activated receptor gamma were similar to murine cell lines. These results suggest that unlike the traditional adipogenic transcription factors, unique differences exist in STAT expression patterns between murine and human adipose cells.

Oral health status of children in a Paediatric Intensive Care Unit

OBJECTIVE

The aim of the present study was to examine the dental status of critically ill children in a Paediatric Intensive Care Unit (PICU) and determine the efficacy of the mouth care received.

DESIGN

Prospective nonrandomized study.

SETTING

The study was carried out in the PICU at Great Ormond Street Hospital for Children.

PATIENTS AND PARTICIPANTS

All children admitted to the PICU during the period of the study were eligible for inclusion. A total of 54 children completed the study.

MEASUREMENTS AND RESULTS

Children were examined for dental caries, plaque accumulation, gingival inflammation and gingival bleeding on admission to the PICU. The examination was repeated on discharge from the Unit. The levels of dental caries found on examination were compared with results from the most recent national surveys carried out in the United Kingdom, and analysed using the one sample t-test. The levels of plaque accumulation, gingival inflammation and gingival bleeding on admission were compared to those on discharge and analysed using the paired sample t-test. Results revealed a very highly significant increase in plaque accumulation (p = 0.001), and a highly significant increase in gingival inflammation (p = 0.006) between admission to the PICU and discharge.

CONCLUSIONS

Results indicate that the present mouth care regimen is not effective in preventing the build up of plaque or maintaining gingival health. These children may therefore be at unnecessary risk from local or systemic spread of oral microorganisms.

Cigarette smoking shortens the duration of daily leisure time physical activity in patients with intermittent claudication

PURPOSE

The authors determined (1) whether peripheral arterial occlusive disease (PAOD) patients who smoke have a reduction in either the duration or intensity of daily physical activities compared with nonsmoking patients, and (2) whether group differences in the pattern of physical activity persisted after controlling for potential confounding variables.

METHODS

A total of 170 smokers and 201 nonsmokers who had quit smoking for at least 1 year prior to investigation were studied. Physical activity patterns were measured using the Minnesota Leisure Time Physical Activity (LTPA) questionnaire. Patients also were characterized on potential covariates such as demographics, comorbid conditions, cardiovascular risk factors, ambulatory measures, peripheral hemodynamics, and anthropometric measures.

RESULTS

The smokers were 37% less physically active than the nonsmokers (87 +/- 90 versus 139 +/- 121 kcal/day; P = 0.027). The reduced total LTPA in the smokers was due to a 28% shorter duration of performing activities (26 +/- 7 versus 36 +/- 22 min/day; P = 0.031), and a 3% lower mean intensity of the activities (3.3 +/- 1.0 versus 3.8 +/- 0.8 kcal/min; P = 0.038). The distance score on the Walking Impairment Questionnaire and the hip circumference were significant covariates of the LTPA measures. After adjusting for these covariates, the total LTPA remained 29% lower in the smokers (P = 0.039), the mean daily duration of LTPA remained 20% lower (P = 0.043), but the mean intensity of LTPA was no longer different between the groups.

CONCLUSION

Compared with their nonsmoking counterparts, claudicants who smoke have a reduced total LTPA because they engage in activities of similar intensity for a shorter duration of time.

Pulmonary embolism in Klippel-Trénaunay syndrome of the upper limb

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Induction of cell cycle arrest and B cell terminal differentiation by CDK inhibitor p18(INK4c) and IL-6

Cell cycle arrest and cell death are tightly coupled to terminal differentiation of B cells to plasma cells in vivo. This process was recapitulated in vitro by stimulation of IgG-bearing human B lymphoblastoid cells with interleukin-6 (IL-6), which led to orderly cell cycle arrest, differentiation, and apoptosis. In terminally differentiated plasmacytoid cells, phosphorylation of pRb was suppressed, correlating with the activation of the D-type cyclin-dependent kinase (CDK) inhibitors p18(INK4c) and p21(WAF1/CIP1). The expression of CDK6, however, remained unchanged. Activation of p18 by IL-6 was rapid, concomitant with marked enhancement of its association with CDK6 and cell cycle arrest. Overexpression of p18 in IgM-bearing lymphoblastoid cells, which differentiated in response to IL-6 but did not exit the cell cycle, reconstituted coupled differentiation and cell cycle arrest. Thus, CDK inhibitors, in particular p18, are likely to play a pivotal role in controlling cell cycle arrest and cell death in terminal differentiation of late-stage B cells to plasma cells via inhibition of pRb phosphorylation by CDK6.

Occupational asthma caused by automated salmon processing

Within 3 months of the opening of a salmon-processing plant in the UK, some workers complained of symptoms suggestive of occupational asthma. A survey of all 291 employees identified 24 (8.2%) with occupational asthma. The employees worked near machines which generated respirable aerosols containing salmon-serum proteins. The IgE response to these proteins was associated with occupational asthma (p < 0.001), with increasing severity of symptoms (p < 0.001), and with working distance from the aerosol source (p = 0.037). The main factor which predisposed to IgE-antibody production and asthma was cigarette smoking (p < 0.001), whereas atopy and a previous allergic history did not. The affected employees were reallocated to a low-exposure worksite and factory ventilation was improved. Eleven showed significant clinical and pulmonary function improvement, and continued in employment. Thirteen who still had symptoms were advised to leave, thereafter becoming symptom-free, and regaining normal respiratory function. Early recognition of symptoms and prompt action to reduce aerosol exposure avoided the long-term reduction in pulmonary functions often associated with occupational asthma.

Problems encountered in meeting the Recommended Dietary Allowances for menus designed according to the Dietary Guidelines for Americans

Forty-three menus that were to be used in a diet manual were designed to meet the requirements of a specific diet; provide 2,200 to 2,400 kcal, unless energy-restricted; meet the 1990 Dietary Guidelines for Americans; meet current recommendations for sodium (2g to 3 g/day), cholesterol (< or = 300 mg/day), and fiber (20g to 30 g/day); and meet or exceed the highest level for adults in the 1989 Recommended Dietary Allowances (RDAs). In addition, regular and low-fat, low-cholesterol menus for 1 week were collected from 11 hospitals throughout Arkansas. Menus were analyzed for energy, cholesterol, and 18 nutrients. Only 11% of the menus met the RDA for zinc. Half of the menus did not meet the RDA for vitamin B-6 and one third did not meet the RDA for iron. Zinc content of the menus was positively correlated (P < .001) with protein (r = .73) and with beef (r = .45). Vitamin B-6 was positively correlated with protein (r = .44, P < .001) and with all meat (r = .38, P < .01). Regular and low-fat, low-cholesterol hospital menus had the same nutrient inadequacies because they did not differ in total servings from any food group. These data indicate that the public may have difficulty choosing a diet that meets both the Dietary Guidelines and the RDAs.

Determinants of collateral development in a canine model with repeated coronary occlusion

It is now accepted that repetitive 2-min coronary occlusion can develop collateral vessels to the area perfused by the occluded coronary artery. However, which factors influence collateral development has yet to be fully elucidated. The goal of the present study was to identify the determinants of the rate of coronary collateral development in dogs undergoing repeated coronary occlusion. The study was conducted in 19 conscious dogs instrumented for measurements of a subendocardial segment length in the area perfused by the left circumflex coronary artery (LCCA), LCCA flow, and left ventricular pressure. An externally inflatable pneumatic occluder was placed around the LCCA. After the recovery from surgery, 2-min LCCA occlusions were conducted eight times daily. Following 141 +/- 61 (SD) LCCA occlusions (20 +/- 7 days), an LCCA occlusion produced no reduction in segment shortening and negligible reactive hyperemia. The total number of LCCA occlusions needed for adequate collateral development (the rate of collateralization) correlated well with the severity of myocardial ischemia during the first occlusion, which was determined mainly by the extent of postsurgical initial collateral circulation. On the other hand, the response to the ischemic stimulus in the later stage of collateral development was independent of the extent of development of the initial postsurgical collaterals. It is concluded that the overall rate of collateral development is slower in dogs with initially poorer collaterals; however, the response of each dog to the ischemic stimulus in the later stage of collateral development was similar among dogs regardless of the extent of the initial collaterals.

Two loci for tuberous sclerosis: one on 9q34 and one on 16p13

32 families informative for the segregation of Tuberous sclerosis (TSC) have been examined for genetic markers on chromosomes 9, 11, 12 and 16. In one large family there was clear evidence of linkage to markers on chromosome 16p13.3 (lodscore with D16S291 of 4.7 at theta = 0) but other families were too small to give individually convincing lodscores. Combined results for all families gave positive results with ABO/DBH on chromosome 9 (max lod 2.63) and with D16S291 on chromosome 16 (max lod 3.98) at values of theta of 0.2 in each case. Further analysis showed strong evidence for heterogeneity with approximately half the families linked to a locus TSC1 on chromosome 9 between ASS and D9S298 and half to TSC2 on chromosome 16 close to D16S291. There was no definite support for a third locus although in many families this could not be excluded. In three families the segregation pattern of TSC remains unexplained. In two of these the family apparently segregates for TSC1 but in each case a single affected individual appeared to exclude the whole of the candidate region. Preliminary analysis of clinical features did not reveal any definite differences in incidence of mental handicap between individuals in different linkage groups or with different sex of the parent of origin. The frequencies of periungual fibromas and facial angiofibromas were also similar in both linkage groups. The difficulties of detecting linkage in small families where there is locus heterogeneity are discussed. The program ZZ was found to be helpful in this respect.

Generation of digoxigenin-labelled double-stranded and single-stranded probes using the polymerase chain reaction

As the polymerase chain reaction (PCR) can be used for the generation of vector-free probes, the optimum conditions for incorporation of digoxigenin-11-dUTP into hepatitis B virus (HBV) probes have been investigated. High yields of double-stranded or single-stranded probes can be obtained by utilizing a pair of primers or one primer alone. The probes were tested by dot-blot hybridization on HBV plasmid DNA, slot-blot hybridization on total cellular RNA of Alexander cells and Southern blot hybridization on cellular DNA of Alexander cells and HBV plasmid DNA. They were also tested by in situ hybridization (ISH) on HBV-positive biopsy liver tissue. A ratio of dig-dUTP:dTTP of 1:3 gave highest sensitivity in DNA hybridization. No loss of amplification efficiency and sensitivity was observed when the final concentration of dig-11-dUTP and dTTP was reduced to 20 microM and 60 microM respectively, compared to 200 microM each of dATP, dCTP, dGTP. Several different sizes of double-strand probes were compared by dot-blot hybridization. Longer probes were more sensitive. Strong signal could also be obtained by combination of two or three small probes, which have overlapping sequences. Single-stranded DNA probes had advantages of simplicity of use, high sensitivity and strand specificity.

Optimization of non-isotopic in situ hybridization on formalin-fixed, paraffin-embedded material using digoxigenin-labelled probes and transgenic tissues

The sensitivity of non-isotopic in situ hybridization (NISH), particularly on formalin-fixed, paraffin-embedded (FFPE) clinical tissues, has been the subject of controversy. Generally, NISH has been regarded as being less sensitive than radiolabelled procedures, although some reports have contradicted this. Accordingly, tissues from mice which were transgenic for variable amounts of the human alpha-1-antitrypsin gene were used to optimize the NISH procedure and to estimate the sensitivity. This approach showed that prolonged incubation of slides in final substrate resulted in high sensitivity--about 13 kb of target DNA. However, this prolonged incubation crucially depended on achieving minimal non-specific background staining. Many factors affected the degree of background staining, but five were particularly important. First, the method of mounting cut sections onto slides. Second, the length of the probe (ideally less than 400 bp). Third, the procedure for proteolytic digestion. Fourth, the denaturation technique, and fifth, the quality of the dextran sulphate used in the hybridization mix. The optimized protocol showed variable patterns of mRNA distribution in the transgenic mouse livers, while DNA distribution appeared uniform.

Effects of coronary occlusion duration on reactive hyperemia in conscious dogs and ponies

Coronary reactive hyperemia duration (RHD) and coronary blood flow debt repayment (BFDR) were compared in conscious dogs and ponies instrumented with coronary artery Doppler flow probes and pneumatic occluders. Additional ponies were instrumented with pacing electrodes. With the use of a Latin square design, eight animals of each species were subjected to a randomized series of nine coronary occlusions ranging from 5 s to 2 min in duration. In both species, postocclusion blood flow velocity rose rapidly and plateaued at similar peak levels relative to control, but in ponies this plateau lasted significantly longer. The interspecies difference in plateau duration increased as a function of coronary occlusion duration (COD). RHD ranged from 19.5 +/- 5.9 to 139.7 +/- 5.9 s in dogs and from 26.6 +/- 9.0 to 395.0 +/- 9.0 s in ponies. The slope of the RHD vs. COD curve was steeper in ponies. BFDR was similar in dogs and ponies at the shortest COD (418.1 +/- 26 vs. 451.4 +/- 58%) but declined in dogs as a function of COD to 232.3 +/- 26%. In ponies, BFDR increased as a function of COD to a maximum of 945.4 +/- 58% with a 60-s occlusion and then declined to 614.3 +/- 58%. RHD was not significantly altered in ponies when heart rate was changed to match that in dogs. Although the underlying basis for these interspecies differences in RHD and BFDR was not determined, the differences were considered to be too large to be explained by animal model differences in coronary conductance, collateral blood flow, or myocardial oxygen consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nitroglycerin and diltiazem on well-developed coronary collateral circulation in conscious dogs

The purpose of the present study was to compare the effects of nitroglycerin and diltiazem on coronary collateral circulation. Studies were conducted in 8 conscious dogs instrumented for the measurement of left circumflex coronary artery (LCCA) flow, subendocardial segment lengths in areas perfused by the LCCA, and left anterior descending coronary artery (LAD). Brief, repeated LCCA occlusions sufficiently developed collateral vessels for the resting metabolic requirement in the LCCA region. One week following the cessation of repeated LCCA occlusions, two-minute coronary occlusions with and without drug pretreatment were performed on separate days. The ischemic responses to coronary occlusions were not altered by diltiazem (50 micrograms/kg, IV), but nitroglycerin (5 micrograms/kg, IV) attenuated myocardial ischemia definitely. The authors conclude that nitroglycerin produces greater effects than diltiazem in attenuating myocardial ischemia in the collateral dependent zone when effects of each drug on systemic and coronary circulation were minimized by pretreatment with small doses.

Bidirectional function of coronary collateral channels in conscious dogs

STUDY OBJECTIVE

The aim was to investigate the bidirectional functional adequacy of collateral perfusion in conscious dogs.

DESIGN

Left circumflex coronary artery (LCCA) occlusions of 1 or 2 min duration were repeated to stimulate the development of collateral perfusion to the LCCA area, and the left anterior descending coronary artery (LAD) was occluded once daily to evaluate the development of retrograde LCCA-LAD flow.

SUBJECTS

7 male mongrel dogs were used, weight 25-28 kg.

MEASUREMENTS AND MAIN RESULTS

Coronary collateral flow from the LCCA to the LAD perfusion area was measured as the abrupt decrease in the LCCA flow (implanted Doppler transducer) upon release of a brief LAD occlusion. Measurements were repeated daily during the development of collaterals induced by repeated, brief occlusions of the LCCA. After 35(SD17) days of such occlusions; there was no sustained reduction in LCCA regional myocardial function during an LCCA occlusion, and reactive hyperaemic repayment following the occlusion was negligible. Before and after collateral development, the LCCA to LAD collateral flow increased from 1.1(0.2) to 8.6(5.1) cm.s-1. LAD systolic segment shortening during the LAD occlusion increased from 2.1(2.0)% (first occlusion) to 19.3(8.6)% (last occlusion).

CONCLUSIONS

LAD to LCCA collaterals serve as functionally significant bidirectional perfusion conduits, and monitoring of collateral perfusion development is practical by measuring the step reduction in LCCA flow upon abrupt release of an LAD occlusion.

Coronary collateral regression in conscious dogs

To study the effect of long-term coronary reperfusion on regression of newly developed collateral vessels, the authors reoccluded the coronary artery for ten minutes following one to fifteen weeks of reperfusion. They repeated one- or two-minute occlusions of the left circumflex coronary artery (LCCA) in 8 conscious dogs. After 401 +/- 202 (SD) minutes of total LCCA occlusion time (35 +/- 19 days), The LCCA occlusion produced no sustained reduction in regional myocardial shortening and negligible reactive hyperemia. Upon reocclusion following a long-term reperfusion, the subendocardial segment shortening in the region at risk deteriorated markedly. At two minutes of occlusion, percent systolic shortening showed minimal values and thereafter gradually returned to the preocclusion resting levels within six to eight minutes of occlusion. In the presence of a resting heart rate similar to that at the time of functional recovery during the LCCA occlusion, long-term reperfusion did not modify the time course of regional functional response to the prolonged coronary occlusion. It is concluded that the newly developed collateral vessels still serve as significant blood-conveying conduits following a considerable period of reperfusion, and it requires approximately six to eight minutes to restore regional myocardial function in the collateral dependent zone following coronary reocclusion.