Incidence of self-reported tuberculosis treatment with community-wide universal testing and treatment for HIV and tuberculosis screening in Zambia and South Africa: A planned analysis of the HPTN 071 (PopART) cluster-randomised trial.

BACKGROUND: HIV is a potent risk factor for tuberculosis (TB). Therefore, community-wide universal testing and treatment for HIV (UTT) could contribute to TB control, but evidence for this is limited. Community-wide TB screening can decrease population-level TB prevalence. Combining UTT with TB screening could therefore significantly impact TB control in sub-Saharan Africa, but to our knowledge there is no evidence for this combined approach. METHODS AND FINDINGS: HPTN 071 (PopART) was a community-randomised trial conducted between November 2013 to July 2018; 21 Zambian and South African communities (with a total population of approximately 1 million individuals) were randomised to arms A (community-wide UTT and TB screening), B (community-wide universal HIV testing with treatment following national guidelines and TB screening), or C (standard-of-care). In a cohort of randomly selected adults (18 to 44 years) enrolled between 2013 and 2015 from all 21 communities (total size 38,474; 27,139 [71%] female; 8,004 [21%] HIV positive) and followed-up annually for 36 months to measure the population-level impact of the interventions, data on self-reported TB treatment in the previous 12 months (self-reported TB) were collected by trained research assistants and recorded using a structured questionnaire at each study visit. In this prespecified analysis of the trial, self-reported TB incidence rates were measured by calendar year between 2014 and 2017/2018. A p-value ≤0.05 on hypothesis testing was defined as reaching statistical significance. Between January 2014 and July 2018, 38,287 individuals were followed-up: 494 self-reported TB during 104,877 person-years. Overall incidence rates were similar across all arms in 2014 and 2015 (0.33 to 0.46/100 person-years). In 2016 incidence rates were lower in arm A compared to C overall (adjusted rate ratio [aRR] 0.48 [95% confidence interval (95% CI) 0.28 to 0.81; p = 0.01]), with statistical significance reached. In 2017/2018, while incidence rates were lower in arm A compared to C, statistical significance was not reached (aRR 0.58 [95% CI 0.27 to 1.22; p = 0.13]). Among people living with HIV (PLHIV) incidence rates were lower in arm A compared to C in 2016 (RR 0.56 [95% CI 0.29 to 1.08; p = 0.08]) and 2017/2018 (RR 0.50 [95% CI 0.26 to 0.95; p = 0.04]); statistical significance was only reached in 2017/2018. Incidence rates in arms B and C were similar, overall and among PLHIV. Among HIV-negative individuals, there were too few events for cross-arm comparisons. Study limitations include the use of self-report which may have been subject to under-reporting, limited covariate adjustment due to the small number of events, and high losses to follow-up over time. CONCLUSIONS: In this study, community-wide UTT and TB screening resulted in substantially lower TB incidence among PLHIV at population-level, compared to standard-of-care, with statistical significance reached in the final study year. There was also some evidence this translated to a decrease in self-reported TB incidence overall in the population. Reduction in arm A but not B suggests UTT drove the observed effect. Our data support the role of UTT in TB control, in addition to HIV control, in high TB/HIV burden settings. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01900977.

Intimate Partner Violence (IPV) and Associated Factors in HPTN 071 (PopART) Study Communities in Zambia and South Africa-A Comparison by HIV Status.

The HPTN 071(PopART) study was a community-randomised trial in Zambia and South Africa, examining the impact of combination-prevention including universal testing and treatment (UTT), on HIV-incidence. This sub-study evaluated factors associated with IPV (physical and/or sexual) to identify differences by HIV status. During 2015-16, a random subset of adults who participated in the first year of the PopART intervention were recruited and standardised questionnaires were administered. Logistic regression was performed to estimate odds ratios of factors associated with IPV. Among > 700 women studied (300 HIV-negative;400 HIV-positive), ~ 20% reported experiencing physical and/or sexual violence in the last 12-months. Sexual violence was similar by HIV status, but physical violence and reporting both physical/sexual violence was more common among HIV-positive women. Spending nights away from the community in the last 12-months was associated with higher odds of IPV among both HIV-negative (aOR 3.17, 95% CI 1.02-9.81) and HIV-positive women (aOR 1.79, 95% CI 0.99-3.24). Among HIV-positive women, financial autonomy was associated with reduced IPV (aOR:0.41,95%CI:0.23-0.75) while pregnancy in the last 12-months (aOR 2.25, 95% CI 1.07-4.74), risk of alcohol dependence (aOR 2.75, 95% CI 1.51-5.00) and risk of mental distress (aOR 2.62, 95% CI 1.33-5.16) were associated with increased IPV. Among HIV-negative women reporting sex in the last 12-months, transactional sex (aOR 3.97, 95% CI 1.02-15.37) and not knowing partner's HIV status (aOR 3.01, 95% CI 1.24-7.29) were associated with IPV. IPV was commonly reported in the study population and factors associated with IPV differed by HIV status. The association of mobility with IPV warrants further research. The high prevalence of harmful alcohol use and mental distress, and their association with IPV among HIV-positive women require urgent attention.

RESUMEN: El estudio HPTN 071 (PopART) fue un ensayo aleatorio-comunitario realizado en Zambia y Sudáfrica, que examinó el impacto de la prevención combinada, incluyendo las pruebas y tratamiento universal (UTT), en la incidencia del VIH. Este subestudio evaluó los factores asociados con la IPV (físicos y / o sexuales) para identificar diferencias en el estado del VIH. Durante 2015-16, un subconjunto aleatorio de adultos fueron reclutados para participar en el primer año de intervención de PopART, donde se administraron cuestionarios estandarizados. Se realizó una regresión logística para estimar las ratios de probabilidad de los factores asociados con la VPI. Entre las > 700 mujeres estudiadas (300 VIH negativas; 400 VIH positivas), ~ 20% informó haber experimentado violencia física y / o sexual en los últimos 12 meses. La violencia sexual fue similar en cuanto al estado del VIH. La denuncia de violencia física y sexual fue más común entre las mujeres VIH positivas. Pasar noches fuera de la comunidad en los últimos 12 meses, se asoció con mayores probabilidades de VPI entre las mujeres VIH negativas (ORa 3,17, 95% IC 1,02­9,81) y las mujeres VIH positivas (ORa 1,79, 95% IC 0,99­3,24). Entre las mujeres VIH positivas, la autonomía financiera se asoció con una reducción de la VPI (ORa 0,41; IC del 95% 0,23-0,75) mientras que en el embarazo en los últimos 12 meses (ORa 2,25; IC del 95% 1,07­4,74), riesgo a la dependencia del alcohol (ORa 2,75% IC 1,51­5,00) y el riesgo de angustia mental (ORa 2,62% IC del 95% 1,33­5,16) se asociaron con un aumento de la VPI. Entre las mujeres VIH negativas que informaron haber tenido relaciones sexuales en los últimos 12 meses, el sexo transaccional (ORa 3.97, 95% CI 1.02­15.37) y el desconocimiento del estado de VIH de la pareja (ORa 3.01, 95% CI 1.24­7.29) se asociaron con IPV. La IPV fue notificada mayoritariamente en la población de estudio y los factores asociados con la IPV diferían según el estado del VIH. La asociación de la movilidad con la IPV justifica una mayor investigación. La alta prevalencia de l consumo nocivo de alcohol y la angustia mental, y su asociación con la VPI entre las mujeres seropositivas, requieren atención urgente.

Improving retention of community-recruited participants in HIV prevention research through Saturday household visits; findings from the HPTN 071 (PopART) study in South Africa.

BACKGROUND: Identifying successful strategies to improve participant retention in longitudinal studies remains a challenge. In this study we evaluated whether non-traditional fieldworker shifts (after hours during the week and weekends) enhanced participant retention when compared to retention during traditional weekday shifts in the HPTN 071 (PopART) population cohort (PC). METHODS: HPTN 071 (PopART) PC participants were recruited and followed up in their homes on an annual basis by research fieldworkers over a 3-4 year period. The average number of successful follow-up visits, where a PC participant was found and retained in the study, was calculated for each of 3 visit schedules (early weekday shift, late weekday shift, and Saturday shift), and standardized to account for variation in fieldwork shift duration. We used one-way univariate analysis of variance (ANOVA) to describe differences in mean-successful visits and 95% confidence intervals between the shift types. RESULTS: Data on 16 651 successful visits were included. Successful visit rates were higher when conducting Saturday visits (14.0; 95% CI: 11.3-16.6) compared to both regular (4.5; 95% CI: 3.7-5.3) and late weekday shifts (5.3; 95% CI: 4.7-5.8) overall and in all subgroup analyses (P<0.001). The successful visit rate was higher amongst women than men were during all shift types (3.2 vs. 1.3, p<0.001). Successful visit rates by shift type did not differ significantly by age, over time, by PC round or by community triplet. CONCLUSION: The number of people living with HIV continues to increase annually. High quality evidence from longitudinal studies remains critical for evaluating HIV prevention and treatment strategies. This study showed a significant benefit on participant retention through introduction of Saturday shifts for home visits and these data can make an important contribution to the emerging body of evidence for improving retention in longitudinal research. TRIAL REGISTRATION: PopART was approved by the Stellenbosch University Health Research Ethics Committees (N12/11/074), London School of Hygiene and Tropical Medicine (6326) ethics committee and the Division of AIDS (DAIDS) (Protocol ID 11865). PopART was registered with ClinicalTrials.gov (registration number NCT01900977 ).

Renal dysfunction by baseline CD4 cell count in a cohort of adults starting antiretroviral treatment regardless of CD4 count in the HIV Prevention Trials Network 071 [HPTN 071; Population Effect of Antiretroviral Therapy to Reduce HIV Transmission (PopART)] study in South Africa.

OBJECTIVES: Renal dysfunction is a significant cause of morbidity and mortality among HIV-positive individuals. This study evaluated renal dysfunction in a cohort of adults who started antiretroviral treatment (ART) regardless of CD4 count at three Department of Health (DOH) clinics included in the HIV Prevention Trials Network 071 (HPTN 071) Population Effect of Antiretroviral Therapy to Reduce HIV Transmission (PopART) trial. METHODS: A retrospective cohort analysis of routine data for HIV-positive individuals starting ART between January 2014 and November 2015 was completed. Incident renal dysfunction was defined as an estimated glomerular filtration rate (eEGFR) < 60 mL/min after ART initiation among individuals with a baseline (pre-ART) eGFR ≥ 60 mL/min. RESULTS: Overall, 2423 individuals, with a median baseline CD4 count of 328 cells/µL [interquartile range (IQR) 195-468 cells/µL], were included in the analysis. Forty-seven individuals had a baseline eGFR < 60 mL/min. Among 1634 nonpregnant individuals started on a tenofovir-containing ART regimen and with a baseline eGFR ≥ 60 mL/min, 27 developed an eGFR < 60 mL/min on ART. Regression analysis showed lower odds of baseline eGFR < 60 mL/min at baseline CD4 counts of > 500 cells/µL [adjusted odds ratio (aOR) 0.29; 95% confidence interval (CI) 0.11-0.80], 351-500 cells/µL (aOR 0.22; 95% CI 0.08-0.59) and 201-350 (aOR 0.48; 95% CI: 0.24-0.97) compared with baseline CD4 counts < 200 cells/µL. CONCLUSIONS: This study showed low rates of renal dysfunction at baseline and on ART, with lower rates of baseline renal dysfunction among individuals with baseline CD4 counts > 200 cells/µL. Strategies that use baseline characteristics, such as age, to identify individuals at high risk of renal dysfunction on ART for enhanced eGFR monitoring may be effective and should be the subject of future research.

[SCARF osteotomy]. / SCARF-Osteotomie.

Hallux valgus is one of the most common deformities of the lower extremity. Multiple etiologies have been discussed, and various techniques have been described. The SCARF osteotomy is indicated for moderate to severe hallux valgus deformities. The technique historically used by carpenters allows immediate postoperative weight bearing and also entails the possibility to correct the distal metatarsal articular angle by rotation of the osteotomy. The SCARF osteotomy has also been successfully used in revision surgeries.

Distemper virus encephalitis exerts detrimental effects on hippocampal neurogenesis.

AIMS: Despite knowledge about the impact of brain inflammation on hippocampal neurogenesis, data on the influence of virus encephalitis on dentate granule cell neurogenesis are so far limited. Canine distemper is considered an interesting model of virus encephalitis, which can be associated with a chronic progressing disease course and can cause symptomatic seizures. METHODS: To determine the impact of canine distemper virus (CDV) infection on hippocampal neurogenesis, we compared post-mortem tissue from dogs with infection with and without seizures, from epileptic dogs with non-viral aetiology and from dogs without central nervous system diseases. RESULTS: The majority of animals with infection and with epilepsy of non-viral aetiology exhibited neuronal progenitor numbers below the age average in controls. Virus infection with and without seizures significantly decreased the mean number of neuronal progenitor cells by 43% and 76% as compared to age-matched controls. Ki-67 labelling demonstrated that hippocampal cell proliferation was neither affected by infection nor by epilepsy of non-viral aetiology. Analysis of CDV infection in cells expressing caspase-3, doublecortin or Ki-67 indicated that infection of neuronal progenitor cells is extremely rare and suggests that infection might damage non-differentiated progenitor cells, hamper neuronal differentiation and promote glial differentiation. A high inter-individual variance in the number of lectin-reactive microglial cells was evident in dogs with distemper infection. Statistical analyses did not reveal a correlation between the number of lectin-reactive microglia cells and neuronal progenitor cells. CONCLUSIONS: Our data demonstrate that virus encephalitis with and without seizures can exert detrimental effects on hippocampal neurogenesis, which might contribute to long-term consequences of the disease. The lack of a significant impact of distemper virus on Ki-67-labelled cells indicates that the infection affected neuronal differentiation and survival of newborn cells rather than hippocampal cell proliferation.

Promotion of experimental thrombus formation by the procoagulant activity of breast cancer cells.

The routine observation of tumor emboli in the peripheral blood of patients with carcinomas raises questions about the clinical relevance of these circulating tumor cells. Thrombosis is a common clinical manifestation of cancer, and circulating tumor cells may play a pathogenetic role in this process. The presence of coagulation-associated molecules on cancer cells has been described, but the mechanisms by which circulating tumor cells augment or alter coagulation remains unclear. In this study we utilized suspensions of a metastatic adenocarcinoma cell line, MDA-MB-231, and a non-metastatic breast epithelial cell line, MCF-10A, as models of circulating tumor cells to determine the thrombogenic activity of these blood-foreign cells. In human plasma, both metastatic MDA-MB-231 cells and non-metastatic MCF-10A cells significantly enhanced clotting kinetics. The effect of MDA-MB-231 and MCF-10A cells on clotting times was cell number-dependent and inhibited by a neutralizing antibody to tissue factor (TF) as well as inhibitors of activated factor X and thrombin. Using fluorescence microscopy, we found that both MDA-MB-231 and MCF-10A cells supported the binding of fluorescently labeled thrombin. Furthermore, in a model of thrombus formation under pressure-driven flow, MDA-MB-231 and MCF-10A cells significantly decreased the time to occlusion. Our findings indicate that the presence of breast epithelial cells in blood can stimulate coagulation in a TF-dependent manner, suggesting that tumor cells that enter the circulation may promote the formation of occlusive thrombi under shear flow conditions.

Temperature-independent silicon subwavelength grating waveguides.

We demonstrate, by experiment and numerical calculations, temperature-independent subwavelength grating waveguides with a periodic composite core composed of alternating regions of silicon and SU-8 polymer. The polymer has a negative thermo-optic (TO) material coefficient that cancels the large positive TO effect of the silicon. Measurements and Bloch mode calculations were carried out over a range of silicon-polymer duty ratios. The lowest measured TO coefficient at a wavelength of 1550 nm is 1.8×10(-6) K(-1); 2 orders of magnitude smaller than a conventional silicon photonic wire waveguide. Calculations predict the possibility of complete cancellation of the silicon waveguide temperature dependence.

Oral masses in two cats.

Incisional biopsies from the oral cavity of 2 adult cats were submitted for histological investigation. Cat No. 1 showed a solitary well-circumscribed neoplasm in the left mandible. Cat No. 2 demonstrated a diffusely infiltrating neoplasm in the left maxilla. Both tumors consisted of medium-size epithelial cells embedded in a fibrovascular stroma. The mitotic index was 0 to 1 mitosis per high-power field. The epithelial cells showed an irregular arrangement forming nests or streams in cat No. 1, whereas a palisading growth was noted in cat No. 2. Both tumors, especially that of cat No. 1, showed multifocal accumulations of amyloid as confirmed by Congo red staining and a distinct green birefringence under polarized light, which lacked cytokeratin immunoreactivity as well as and AL and AA amyloid immunoreactivity. In addition, the amyloid in cat No. 2 was positive for the odontogenic ameloblast-associated protein, formerly termed APin. In sum, both cats suffered from an amyloid-producing odontogenic tumor, but their tumors varied with respect to morphology and type of amyloid produced.

[Feline papillomavirus infection in a cat with Bowen-like disease and cutaneous squamous cell carcinoma]. / Feline Papillomavirusinfektion bei einer Katze mit Bowen-like disease und kutanem Plattenepithelkarzinom.

A cutaneous mass in the neck was excised in a 13-year-old cat. Histopathological examination of the resected tissue revealed a multicentric squamous cell carcinoma in situ resembling Bowen's disease of man. The tumor showed a multifocal transformation to an infiltrative squamous cell carcinoma. Histological and immunohistological findings excluded actinic keratosis and feline viral plaques and allowed a classification as an irregular non-hyperkeratotic type of multicentric squamous cell carcinoma in situ. As a possible causative agent feline papillomavirus type 2 was detected using nested PCR in formalin-fixed material.

[Deformity-associated treatment of the hallux valgus complex]. / Deformitätsassoziierte Behandlung des Hallux-valgus-Komplexes.

Hallux valgus represents a combined deformity with malpositioning of the big toe in the metatarsophalangeal joint and metatarsal splaying due to metatarsus primus varus formation. It is defined on the basis of joint condition of the metatarsophalangeal and tarsometatarsal (TMT) joints, the extent and congruence or incongruence of malposition, mobility of the metatarsophalangeal joint and TMT stability. Basic resection appears to be indicated only in exceptional cases. Depending on the degree of severity, deformities can be corrected by means of distal, diaphyseal or proximal osteotomies and TMT arthrodeses. Any correction requires the use of subtle soft tissue surgery with recentering of the tendon, tightening of the medial capsule and abductor hallucis and releasing the lateral capsule. A check-list-like analysis of hallux valgus deformity helps determine the ideal procedure and avoid over- or under-treatment.

The inter- and intraobserver reliability for the radiological parameters of flatfoot, before and after surgery.

Aims: Various radiological parameters are used to evaluate a flatfoot deformity and their measurements may differ. The aims of this study were to answer the following questions: 1) Which of the 11 parameters have the best inter- and intraobserver reliability in a standardized radiological setting? 2) Are pre- and postoperative assessments equally reliable? 3) What are the identifiable sources of variation? Patients and Methods: Measurements of the 11 parameters were recorded on anteroposterior and lateral weight-bearing radiographs of 38 feet before and after surgery for flatfoot, by three observers with different experience in foot surgery (A, ten years; B, three years; C, third-year orthopaedic resident). The inter- and intraobserver reliability was calculated. Results: Preoperative interobserver reliability was high for four, moderate for five, and low for two parameters. Postoperative interobserver reliability was high for four, moderate for five, and low for two parameters. Intraobserver reliability was excellent for all parameters preoperatively as recorded by observer A (PB) and B (MP), and for eight parameters as recorded by observer C (SR). Intraobserver reliability was excellent for ten parameters postoperatively as recorded by observer A and B, and for eight parameters as recorded by observer C. Conclusion: The following parameters can be recommended. For preoperative and postoperative evaluation of flatfoot: anteroposterior, talonavicular coverage angle; lateral, talometatarsal I angle, calcaneal pitch angle, and cuneiform-medial height (high interobserver reliability); and anteroposterior, talometatarsal II angle; lateral, talocalcaneal angle,tibiocalcaneal angle (moderate interobserver reliability). For more experienced observers, we also recommend the anteroposterior talometatarsal I angle (moderate reliability). The inter- and intraobserver reliability for most parameters were similar pre- and postoperatively. The experience of the observer and the definition and ability to measure the parameters themselves were sources of variation. Cite this article: Bone Joint J 2018;100-B:596-602.

Mid-term follow-up of patients with hindfoot arthrodesis with retrograde compression intramedullary nail in Charcot neuroarthropathy of the hindfoot.

AIMS: Hindfoot arthrodesis with retrograde intramedullary nailing has been described as a surgical strategy to reconstruct deformities of the ankle and hindfoot in patients with Charcot arthropathy. This study presents case series of Charcot arthropathy patients treated with two different retrograde intramedullary straight compression nails in order to reconstruct the hindfoot and assess the results over a mid-term follow-up. PATIENTS AND METHODS: We performed a retrospective analysis of 18 consecutive patients and 19 operated feet with Charcot arthropathy who underwent a hindfoot arthrodesis using a retrograde intramedullary compression nail. Patients were ten men and eight women with a mean age of 63.43 years (38.5 to 79.8). We report the rate of limb salvage, complications requiring additional surgery, and fusion rate in both groups. The mean duration of follow-up was 46.36 months (37 to 70). RESULTS: The limb salvage rate was 16 of 19 limbs. Three patients had to undergo below-knee amputation due to persistent infection followed by osteomyelitis resistant to parenteral antibiotic therapy and repeated debridement. Complications including infection, hardware removal, nonunion, and persistent ulcers requiring further intervention were also observed. Postoperative functional scores revealed significant improvement compared with preoperative scores on American Orthopaedic Foot and Ankle Society (AOFAS) - Hindfoot scale, Foot Function Index (FFI), visual analogue scale (VAS), and Foot and Ankle Outcome Score (FAOS). CONCLUSION: The use of retrograde intramedullary compression nail results in good rates of limb salvage when used for hindfoot reconstruction in patients with Charcot arthropathy. Cite this article: Bone Joint J 2018;100-B:190-6.

Exosites in the substrate specificity of blood coagulation reactions.

The specificity of blood coagulation proteinases for substrate, inhibitor, and effector recognition is mediated by exosites on the surfaces of the catalytic domains, physically separated from the catalytic site. Some thrombin ligands bind specifically to either exosite I or II, while others engage both exosites. The involvement of different, overlapping constellations of exosite residues enables binding of structurally diverse ligands. The flexibility of the thrombin structure is central to the mechanism of complex formation and the specificity of exosite interactions. Encounter complex formation is driven by electrostatic ligand-exosite interactions, followed by conformational rearrangement to a stable complex. Exosites on some zymogens are in low affinity proexosite states and are expressed concomitant with catalytic site activation. The requirement for exosite expression controls the specificity of assembly of catalytic complexes on the coagulation pathway, such as the membrane-bound factor Xa*factor Va (prothrombinase) complex, and prevents premature assembly. Substrate recognition by prothrombinase involves a two-step mechanism with initial docking of prothrombin to exosites, followed by a conformational change to engage the FXa catalytic site. Prothrombin and its activation intermediates bind prothrombinase in two alternative conformations determined by the zymogen to proteinase transition that are hypothesized to involve prothrombin (pro)exosite I interactions with FVa, which underpin the sequential activation pathway. The role of exosites as the major source of substrate specificity has stimulated development of exosite-targeted anticoagulants for treatment of thrombosis.

Evidence for a functional role of calsequestrin 2 in mouse atrium.

AIM: Several genetically modified mice models were studied so far to investigate the role of cardiac calsequestrin (CSQ2) for the contractile function of the ventricle and for the occurrence of ventricular tachycardia. Using a CSQ2 knockout mouse, we wanted to study also the atrial function of CSQ2. METHODS: The influence of CSQ2 on atrial function and, for comparison, ventricular function was studied in isolated cardiac preparations and by echocardiography as well as electrocardiography in mice with deletion of CSQ2. RESULTS: Using deletion of exon 1, we have successfully generated a constitutive knockout mouse of the calsequestrin 2 gene (CSQ2-/- ). CSQ2 protein was absent in the heart (atrium, ventricle), but also in oesophagus and skeletal muscle of homozygous knockout mice. In 6-month-old CSQ2-/- mice, relative left atrial weight was increased, whereas relative heart weight was unchanged. The staircase phenomena in paced left atrial preparations on force of contraction and the post-rest potentiation were different between wild type and CSQ2-/- indicative for a decreased sarcoplasmic Ca2+ load and supporting an important role of CSQ2 also in the atrium. The incidence of arrhythmias was increased in CSQ2-/- . In 2-year-old CSQ2-/- mice, cardiac hypertrophy and heart failure were noted possibly as a result of chronically increased cytosolic Ca2+ levels. CONCLUSION: These data suggest a functional role of CSQ2 not only in the ventricle but also in the atrium of mammalian hearts. Loss of CSQ2 function can cause not only arrhythmias, but also cardiac hypertrophy and heart failure.

Pathogen activators of plasminogen.

Group A streptococci (GAS) express soluble and surface-bound virulence factors. Secreted streptokinase (SK) allelic variants exhibit varying abilities to activate host plasminogen (Pg), and GAS pathogenicity is associated with Pg activation and localization of the resulting plasmin (Pm) on the bacterial surface to promote dissemination. The various mechanisms by which GAS usurp the host proteolytic system are discussed, including the molecular sexuality mechanism of conformational activation of the Pg zymogen (Pg*) and subsequent proteolytic activation of substrate Pg by the S•KPg* and SK•Pm catalytic complexes. Substantial progress has been made to delineate both processes in a unified mechanism. Pm coats the bacteria by direct and indirect binding pathways involving plasminogen-binding group A streptococcal M-like (PAM) protein and host fibrin(ogen). Transgenic mouse models using human Pg are being optimized to mimic infections by SK variants in humans and to define in vivo combined mechanisms of these variants and PAM.

Characterization of bothrojaracin interaction with human prothrombin.

Bothrojaracin (BJC) is a 27-kD snake venom protein from Bothrops jararaca that has been characterized as a potent thrombin inhibitor. BJC binds to exosites I and II, with a dissociation constant of 0.7 nM, and influences but does not block the proteinase catalytic site. BJC also binds prothrombin through an interaction that has not been characterized. In the present work we characterize the interaction of BJC with prothrombin quantitatively for the first time, and identify the BJC binding site on human prothrombin. Gel filtration chromatography demonstrated calcium-independent, 1:1 complex formation between fluorescein-labeled BJC ([5F]BJC) and prothrombin, whereas no interactions were observed with activation fragments 1 or 2 of prothrombin. Isothermal titration calorimetry showed that binding of BJC to prothrombin is endothermic, with a dissociation constant of 76 +/- 32 nM. The exosite I-specific ligand, hirudin(54-65) (Hir(54-65) (SO(3)(-)), displaced competitively [5F]BJC from prothrombin. Titration of the fluorescent hirudin(54-65) derivative, [5F]Hir(54-65)(SO(3)(-)), with human prothrombin showed a dissociation constant of 7.0 +/- 0.2 microM, indicating a approximately 100-fold lower binding affinity than that exhibited by BJC. Both ligands, however, displayed a similar, approximately 100-fold increase in affinity for exosite I when prothrombin was activated to thrombin. BJC efficiently displaced [5F]Hir(54-65)(SO(3)(-)) from complexes formed with thrombin or prothrombin with dissociation constants of 0.7 +/- 0.9 nM and 11 +/- 80 nM, respectively, indicating that BJC and Hir(54-65)(SO(3)(-)) compete for the same exosite on these molecules. The results indicate that BJC is a potent and specific probe of the partially exposed anion-binding exosite (proexosite I) of human prothrombin.

Effect of early onset angiotensin converting enzyme inhibition on myocardial capillaries.

We investigated the preventive effects of long-term treatment with the angiotensin converting enzyme inhibitor ramipril on myocardial left ventricular hypertrophy and capillary length density in spontaneously hypertensive rats. Rats were treated in utero and subsequently up to 20 weeks of age with a high dose (1 mg/kg per day) or with a low dose (0.01 mg/kg per day) of ramipril. Animals given a high dose of ramipril remained normotensive, whereas those given a low dose developed hypertension in parallel to vehicle-treated controls. At the end of the treatment period, converting enzyme activity in heart tissue was inhibited dose-dependently in the treated groups. Both groups revealed an increase in myocardial capillary length density together with increased myocardial glycogen and reduced citric acid concentrations. Left ventricular mass was reduced only in high dose- but not in low dose-treated animals. Our results demonstrate that early onset treatment with a converting enzyme inhibitor can induce myocardial capillary proliferation, even at doses too low to antagonize the development of hypertension or left ventricular hypertrophy. We hypothesize that potentiation of kinins is responsible for this effect, probably by augmenting myocardial blood flow, which is a well-known trigger mechanism of angiogenesis in the heart.