Adherence to the 2017 Clinical Practice Guidelines for Pediatric Hypertension in Safety-Net Clinics

Importance

The 2017 Clinical Practice Guideline (CPG) for the diagnosis and management of pediatric hypertension (PHTN) categorizes a greater proportion of children with elevated blood pressure and PHTN, yet several barriers to CPG adherence have been noted.

Objective

To assess adherence to the 2017 CPG for the diagnosis and management of PHTN and use of a clinical decision support (CDS) tool to calculate blood pressure percentiles.

Design, Setting, and Participants

This cross-sectional study used electronic health record-extracted data from January 1, 2018, to December 31, 2019, among patients visiting 1 of 74 federally qualified health centers in AllianceChicago, a national Health Center Controlled Network. Children and adolescents (aged 3-17 years; hereinafter referred to as children) who attended at least 1 visit and had at least 1 blood pressure reading at or above the 90th percentile or diagnosis of elevated blood pressure or PHTN were eligible for data to be included in the analysis. Data were analyzed from September 1, 2020, to February 21, 2023.

Exposures

Blood pressure at or above the 90th or 95th percentile.

Main Outcomes and Measures

Diagnosis of PHTN (International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10], code I10) or elevated blood pressure (ICD-10 code R03.0) and CDS tool use; blood pressure management (antihypertensive medication, lifestyle counseling, referral); and follow-up visit attendance. Descriptive statistics described the sample and rates of guideline adherence. Logistic regression analyses identified patient- and clinic-level associations with guideline adherence.

Results

The sample consisted of 23 334 children (54.9% boys; 58.6% White race; median age, 8 [IQR, 4-12] years). Guideline-adherent diagnosis was observed in 8810 children (37.8%) with blood pressure at or above the 90th percentile and 146 of 2542 (5.7%) with blood pressure at or above the 95th percentile at 3 or more visits. The CDS tool was used to calculate blood pressure percentiles in 10 524 cases (45.1%) and was associated with significantly greater odds of PHTN diagnosis (odds ratio, 2.14 [95% CI, 1.10-4.15]). Among 15 422 children with blood pressure at or above the 95th percentile, antihypertensive medication was prescribed to 831 (5.4%), lifestyle counseling was provided to 14 841 (96.2%), and blood pressure-related referrals were given to 848 (5.5%). Guideline-adherent follow-up was observed in 8651 of 19 049 children (45.4%) with blood pressure at or above the 90th percentile and 2598 of 15 164 (17.1%) with blood pressure at or above the 95th percentile. Differences in guideline adherence by patient- and clinic-level factors were observed.

Conclusions and Relevance

In this study, fewer than 50% of children with elevated blood pressure had a guideline-adherent diagnosis code or attended guideline-adherent follow-up. Using a CDS tool was associated with guideline-adherent diagnosis, but the tool was underused. Further work is needed to understand how to best support implementation of tools promoting PHTN diagnosis, management, and follow-up.

Predicting Postpartum Transition to Primary Care in Community Health Centers

INTRODUCTION

Although the transition to primary care after routine postpartum care has been recommended to mitigate adverse maternal outcomes, little is known about real-world transition patterns. The objective of this study was to describe the patterns and predictors of transition in a postpartum cohort receiving care at federally qualified health centers and a subcohort of clinically high-risk patients.

METHODS

Electronic health record data collected between 2017 and 2019 were analyzed in 2021 for unadjusted analyses and multivariable regression models for both the full and high-risk cohorts. The primary outcome was completion of a primary care visit within 6 months of delivery. Primary predictors in both cohorts were insurance loss, postpartum visit, first-trimester visit, and medical visit within the year prepregnancy; for the full cohort, high-risk status was also studied.

RESULTS

The full cohort (N=7,926) analysis showed that 17.3% completed a primary care visit. In unadjusted and adjusted analysis, all 5 predictors were significantly associated with primary care visit completion; 25.0% of high-risk patients completed a primary care visit, and patients who lost insurance had 66% lower odds of primary care visit completion (95% CI=0.24, 0.48). In unadjusted and adjusted analysis for the high-risk cohort (n=1,956, 24.7% of full cohort), all predictors except postpartum visit were significantly associated with primary care visit completion.

CONCLUSIONS

Postpartum patients at federally qualified health centers transitioned to primary care at low rates; insurance loss was one significant barrier to care. Strategies to increase continuity, including improving insurance access, should be studied. Future research is needed to study structural inequity, the impact of primary care on maternal outcomes, and patient experience.

Development of a novel clinical decision support tool for diabetes prevention and feasibility of its implementation in primary care

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Clinical decision support may represent a strategy for promoting diabetes prevention in primary care.

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We developed a novel clinical decision support tool with input from primary care providers.

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This clinician-facing tool was associated with improvements in processes of prediabetes care.

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Exploratory analyses found small, but nonsignificant weight loss associated with its use.

Prediabetes impacts 88 million U.S. adults, yet uptake of evidence-based treatment with intensive lifestyle interventions and metformin remains exceedingly low. After incorporating feedback from 15 primary care providers collected during semi-structured interviews, we developed a novel Prediabetes Clinical Decision Support (PreDM CDS) from August 2019 to February 2020. This tool included order options enabling prediabetes management in a single location within the electronic health record. We conducted a retrospective observational study examining the feasibility of implementing this tool at Erie Family Health Centers, a large community health center, examining its use and related outcomes among patients for whom it was used vs not. Overall, 7,424 eligible patients were seen during the implementation period (February 2020 to August 2021), and the PreDM CDS was used for 108 (1.5 %). Using the PreDM CDS was associated with higher rates of hemoglobin A1c orders (70.4 % vs 22.2 %; p < 0.001), lifestyle counseling (38.0 % vs 7.8 %; p < 0.001), and metformin prescription orders (5.6 % vs 2.6 %; p = 0.06). Exploratory analyses revealed small, nonsignificant weight loss among patients for whom the PreDM CDS was used. This study demonstrates the feasibility of developing and implementing the PreDM CDS in primary care. Its low use was likely related to not imposing an interruptive ‘pop-up’ alert, as well as major changes in workflows and clinical priorities during the Covid-19 pandemic. Use of the tool was associated with improved process outcomes. Future efforts with the PreDM CDS should follow standard CDS implementation processes that were not possible due to the Covid-19 pandemic.

Use of diamond sensors for a high-flux, high-rate X-ray pass-through diagnostic

X-ray free-electron lasers (XFELs) deliver pulses of coherent X-rays on the femtosecond time scale, with potentially high repetition rates. While XFELs provide high peak intensities, both the intensity and the centroid of the beam fluctuate strongly on a pulse-to-pulse basis, motivating high-rate beam diagnostics that operate over a large dynamic range. The fast drift velocity, low X-ray absorption and high radiation tolerance properties of chemical vapour deposition diamonds make these crystals a promising candidate material for developing a fast (multi-GHz) pass-through diagnostic for the next generation of XFELs. A new approach to the design of a diamond sensor signal path is presented, along with associated characterization studies performed in the XPP endstation of the LINAC Coherent Light Source (LCLS) at SLAC. Qualitative charge collection profiles (collected charge versus time) are presented and compared with those from a commercially available detector. Quantitative results on the charge collection efficiency and signal collection times are presented over a range of approximately four orders of magnitude in the generated electron-hole plasma density.

A stakeholder-driven method for selecting implementation strategies: a case example of pediatric hypertension clinical practice guideline implementation

Background

This article provides a generalizable method, rooted in co-design and stakeholder engagement, to identify, specify, and prioritize implementation strategies. To illustrate this method, we present a case example focused on identifying strategies to promote pediatric hypertension (pHTN) Clinical Practice Guideline (CPG) implementation in community health center-based primary care practices that involved meaningful engagement of pediatric clinicians, clinic staff, and patients/caregivers. This example was chosen based on the difficulty clinicians and organizations experience in implementing the pHTN CPG, as evidenced by low rates of guideline-adherent pHTN diagnosis and treatment.

Methods

We convened a Stakeholder Advisory Panel (SAP), comprising 6 pediatricians and 5 academic partners, for 8 meetings (~12 h total) to rigorously identify determinants of pHTN CPG adherence and to ultimately develop a testable multilevel, multicomponent implementation strategy. Our approach expanded upon the Expert Recommendations for Implementation Change (ERIC) protocol by incorporating a modified Delphi approach, user-centered design methods, and the Implementation Research Logic Model (IRLM). At the recommendation of our SAP, we gathered further input from youth with or at-risk for pHTN and their caregivers, as well as clinic staff who would be responsible for carrying out facets of the implementation strategy.

Results

First, the SAP identified 17 determinants, and 18 discrete strategies were prioritized for inclusion. The strategies primarily targeted determinants in the domains of intervention characteristics, inner setting, and characteristics of the implementers. Based on SAP ratings of strategy effectiveness, feasibility, and priority, three tiers of strategies emerged, with 7 strategies comprising the top tier implementation strategy package. Next, input from caregivers and clinic staff confirmed the feasibility and acceptability of the implementation strategies and provided further detail in the definition and specification of those strategies.

Conclusions

This method—an adaptation of the ERIC protocol—provided a pragmatic structure to work with stakeholders to efficiently identify implementation strategies, particularly when supplemented with user-centered design activities and the intuitive organizing framework of the IRLM. This generalizable method can help researchers identify and prioritize strategies that align with the implementation context with an increased likelihood of adoption and sustained use.

Disparities in Elevated Body Mass Index in Youth Receiving Care at Community Health Centers

Childhood obesity has increased significantly in the United States. Racial subgroups are often grouped into categories in research, limiting our understanding of disparities. This study describes the prevalence of obesity among youth of diverse racial and ethnic backgrounds receiving care at community health centers (CHCs). This cross-sectional study describes the prevalence of elevated body mass index (BMI) (≥85th percentile) and obesity (≥95th percentile) in youth aged 9 to 19 years receiving care in CHCs in 2014. Multilevel logistic regression estimated the prevalence of elevated BMI and obesity by age, race/ethnicity, and sex. Among 64 925 youth, 40% had elevated BMI and 22% were obese. By race, obesity was lowest in the combined Asian/Pacific Islander category (13%); however, when subgroups were separated, the highest prevalence was among Native Hawaiians (33%) and Other Pacific Islanders (42%) and the lowest in Asians. By sex, Black females and Hispanic and Asian males were more likely to be obese. By age, the highest prevalence of obesity was among those aged 9 to 10 years (25%). Youth served by CHCs have a high prevalence of obesity, with significant differences observed by race, sex, and age. Combining race categories obscures disparities. The heterogeneity of communities warrants research that describes different populations to address obesity.

Under‐recognition of pediatric hypertension diagnosis: Examination of 1 year of visits to community health centers

Pediatric hypertension is associated with significant target organ damage in children and cardiovascular morbidity in adulthood. Appropriate diagnosis and management per guideline recommendations are inconsistent. In this study, we determined the proportion of missed diagnosis of hypertension and prehypertension and appropriate follow‐up in pediatric patients, stratified by sex, age, race/ethnicity, and weight status. Based on the electronic health record (EHR) data from eight federally qualified health centers, among 62,982 children aged 3 to 18 years, 6233 (10%) had at least one abnormal blood pressure (BP) measurement over twelve months. Among those children whose recorded BPs met the criteria for prehypertension (N = 6178), 14.6% had a diagnosis in the EHR. These children were more likely to be White and have obesity compared with children who met the criteria but were not diagnosed with prehypertension. Among those who met the criteria for hypertension (N = 55), 41.8% had a diagnosis of hypertension in the EHR. Being diagnosed with hypertension was not associated with any examined patient characteristics. Over eleven months, 2837 children had BP ≥ 95th percentile on ≥ 1 visit. Only 13% had guideline‐adherent follow‐up within 1 month and were more likely to be older, female, and of Hispanic ethnicity or “other” race. Over six months, 2902 children had BP ≥ 90th percentile on one visit. 41% had guideline‐adherent follow‐up within 6 months and were more likely to be older, of either White, Hispanic, Asian race, or Hispanic ethnicity. In a community‐based setting, pediatric hypertension and prehypertension were persistently underdiagnosed with low adherence to recommended follow‐up.

Optimizing the implementation of a population panel management intervention in safety-net clinics for pediatric hypertension (The OpTIMISe-Pediatric Hypertension Study)

BACKGROUND

Though clinical practice guidelines are available, the diagnosis of pediatric hypertension (HTN) is often missed. Management may not follow guidelines due to the measurement challenges in children, complexity of interpreting youth blood pressure standards that are dependent on height, age, and sex, familiarity with diagnostic criteria, and variable comfort with management of pediatric HTN among providers. Evidence suggests that wide adoption and adherence to pediatric HTN guidelines would result in lower cardiovascular disease and kidney damage in adulthood. The proposed project will develop an implementation strategy package to increase adherence to clinical practice guidelines for pediatric HTN within safety-net community health centers (CHCs). The centerpiece of which is a provider-facing population panel management (PPM) tool and point-of-care clinical decision support (CDS). Prior research indicates that multiple discrete implementation strategies (e.g., stakeholder involvement, readiness planning, training, ongoing audit and feedback) are needed to institute practice- and provider-level adoption of such tools.

METHODS

Using participatory research methods involving stakeholders from a practice-based research network of CHCs, with input from scientific advisors, the project aims to (1) employ user-centered design methods to tailor an existing CDS tool for use at the point of care and optimize cohort management with a PPM tool to support adherence to the latest pediatric HTN guidelines, and (2) use a stakeholder-driven method for selecting implementation strategies that support tool adoption and increase guideline-adherent physician behaviors. Multilevel process evaluation using surveys and key informant interview data will assess the acceptability, adoption, appropriateness, cost, and feasibility of the PPM tool and its multicomponent implementation strategy package. Usability testing will be conducted with the PPM tool to iteratively refine features and ensure proper functionality.

DISCUSSION

The proposed research has the potential to improve identification, diagnosis, and management of HTN in primary care settings for high-risk youth by assisting healthcare providers in implementing the American Academy of Pediatrics' 2017 guidelines using an EHR-integrated PPM tool with CDS. Should the strategy package for PPM tool adoption be successful for pediatric HTN, findings will be translatable to other settings and PPM of other chronic cardiovascular conditions affecting overall population health.

Pediatric hypertension: diagnostic patterns derived from electronic health records

Background

Pediatric hypertension is a serious problem associated with target organ damage in children and an increased risk for adult hypertension. African-American and Latino children are disproportionately affected. Unfortunately, due to a variety of factors, including the complexity of blood pressure (BP) standards, pediatric hypertension is undiagnosed in the majority of cases. We sought to identify factors associated with correct diagnosis and to better understand diagnosis of hypertension by studying the diagnostic paths of a small number of children.

Methods

Data were extracted from electronic health records (EHRs) of children who met criteria for hypertension. Logistic regression was used to identify factors associated with correct diagnosis. Diagnostic paths for 20 diagnosed children were extracted through chart review and analyzed.

Results

Among 1478 hypertensive children, only 85 were diagnosed (6.1%). Age ≥12 compared to age ≤6 was associated with correct diagnosis [odds ratio (OR) of 1.96, 95% confidence interval (CI) (1.16, 3.32)]. Diagnostic paths revealed that primary care providers (PCPs) make the diagnosis based on multiple readings over time and order laboratory tests appropriately.

Conclusions

Hypertension is missed in a large proportion of all children. Effective, systematic approaches to diagnosis are necessary.

Treatment of hypertension in type 2 diabetes

Hypertension is one of the most common medical conditions in the United States, affecting 50 million American adults and accounting for one of four physician office visits. It is often undetected and undertreated, creating significant public health consequences. In diabetes, hypertension is an even greater problem, as diabetes has become the most common single cause of end-stage renal disease (ESRD) in the world, and diabetes is increasing in prevalence. The most important factor in slowing the decline of renal function in diabetes is aggressive treatment of hypertension. Recent guidelines have emphasized that the target blood pressure levels for patients with diabetes should be lower than in other hypertensive groups. The best specific approach for the treatment of hypertension in diabetic patients is the subject of much debate. It may be in the end that the specific drug choice has less overall importance than the actual attainment of adequate blood pressure control. In addition, more credence must be placed on the value of treating systolic hypertension than has traditionally been given. Coexisting diabetes and hypertension are a common clinical scenario that can set off a vicious cycle of increasing renal damage, rising blood pressure, and increased cardiovascular morbidity and mortality. Treatment often requires multiple drugs to effectively preserve renal function and prevent complications.

Use of curanderismo in a public health care system

BACKGROUND

Curanderismo ("the healing") is a centuries-old synthesis of Mexican Indian culture and beliefs.

OBJECTIVE

To evaluate the rate of use of curanderismo among Hispanic subjects seeking medical care at the Denver Health Medical Center, Denver, Colo.

METHODS

We conducted a survey of 405 Hispanic subjects attending outpatient primary and urgent care clinics at Denver Health Medical Center, the public hospital system for Denver. The main outcome measure was independent predictors of use of curanderos.

RESULTS

Of the 405 subjects, 118 (29.1%) (95% confidence interval, 20.9-37.3) had been to a curandero at some time in their lives. Of all the subjects, 91.3% knew what a curandero was. Univariate analyses demonstrated an association between those who had been to a curandero and level of income, level of education, and whether the subject was bilingual. The results of fitting a stepwise logistic regression model revealed an independent association with subjects who had been to a curandero and level of household income (>$20 000 vs <$10 000), with an odds ratio of 2.19 (95% confidence interval, 1.20-4.01) (P =.01), and level of education (post--high school vs elementary school), with an odds ratio of 3.16 (95% confidence interval, 1.45-6.86) (P =.004).

CONCLUSIONS

Many Hispanic patients who receive their health care at a public hospital system use the services of curanderos. This potentially has important implications for their health care.

Mechanisms by which T7 lysozyme specifically regulates T7 RNA polymerase during different phases of transcription

Bacteriophage T7 lysozyme binds to T7 RNA polymerase (RNAP) and regulates its transcription by differentially repressing initiation from different T7 promoters. This selective repression is due in part to a lysozyme-induced increase in the KNTP of the initiation complex (IC) and to intrinsically different NTP concentration requirements for efficient initiation from different T7 promoters. While lysozyme represses initiation, once the enzyme has left the promoter and formed an elongation complex (EC) it is generally resistant to the effects of lysozyme. The mechanism by which the inhibitory effects of lysozyme are largely restricted to the initiation phase of transcription is not well understood. We find that T7 lysozyme destabilizes initial transcription complexes (ITCs) and increases the rate of release of transcripts from these complexes but does not destabilize ECs. However, if the RNA:RNAP interaction proposed to be important for EC stability is disrupted by proteolysis of the RNA-binding domain or use of templates which interfere with establishment of this RNA:RNAP interaction, the EC becomes sensitive to lysozyme. Comparison of the X-ray structures of T7RNAP and of a T7RNAP:T7 lysozyme complex reveals that lysozyme causes the C terminus of the polymerase to flip out of the active site. Experiments in which carboxypeptidase A is used to probe the lysozyme-induced exposure of the C terminus reveal a large decrease in carboxypeptidase sensitivity following transcription initiation, suggesting that interactions with the 3'-end of the RNA help stabilize the active site in a functional (carboxypeptidase protected) conformation. Thus, the resistance of the EC to lysozyme appears to be due to the consecutive establishment of two sets of RNA:RNAP interactions. The first is made with the 3'-end of the RNA and helps stabilize a functional conformation of the active site, thereby suppressing the effects of lysozyme on KNTP. The second is made with a more upstream element of the RNA and keeps the EC from being destabilized by lysozyme binding.

Efficient synthesis of nucleic acids heavily modified with non-canonical ribose 2'-groups using a mutantT7 RNA polymerase (RNAP)

A T7 RNAP mutant (Y639F) which eliminates discrimination of the chemical character of the NTP ribose 2'-group, facilitates incorporation of non-canonicalsubstrates into nucleic acids. However, transcripts containing a high percentage of non-canonical NMPs are poorly extended due to effects of the 2'-substituents on the transcript:template hybrid conformation. We tested the addition of compounds that stabilize A-type helix geometry to the reaction. High concentrations of polyamines, together with other changes in reaction conditions, greatly increased the synthesis of transcripts heavily substituted with non-canonical ribose 2'-groups. Template structures that facilitate promoter opening increased the efficiency of reactions where non-canonical substrates were incorporated during transcription of +1 to +6.

Initiating a chaplaincy program for a hospital police department

The authors discuss the creation of a police chaplain program at their hospital--why it was needed, the preparations that were necessary, the recruitment process, and the important role the police chaplain plays.

Mechanism of ribose 2'-group discrimination by an RNA polymerase

The mechanism by which T7 RNA polymerase (RNAP) discriminates between rNTP and dNTP substrates has been characterized. During transcript elongation T7 RNAP uses rNTPs 70-80-fold more efficiently than dNTPs. Discrimination of the hydrogen-bonding character of the ribose 2'-substituent contributes a largely Km-mediated factor of approximately 20 to this preference for rNTPs. Discrimination of 2'-substituent H-bonding character appears to be made through a hydrogen bond to the hydroxyl group of tyrosine 639. This hydrogen bond makes little net contribution to either rNTP ground or transition state binding energy apparently because it is balanced by the energy of desolvation of the tyrosine hydroxyl. This mechanism may reflect a strategy to facilitate translocation by minimizing contributions from polymerase-NMP moiety interactions to NTP binding energy so as to minimize the affinity of the NTP binding site for the 3'-NMP of the product nucleic acid.

The beta-tubulin monomer release factor (p14) has homology with a region of the DnaJ protein

p14 is a molecular chaperone involved in beta-tubulin folding which catalyzes the release of beta-tubulin monomers from intermediate complexes. Here we demonstrate that active p14 protein which we have purified from an overproducing Escherichia coli strain can also release beta-tubulin monomers from tubulin dimers in the presence of an additional cofactor (Z). Analysis of p14 secondary structure suggests that this protein may belong to a family of conserved proteins which share structural similarities with the J-domain of DnaJ. We have constructed deletions and site-directed mutations in the p14 gene. A single D to E mutation in the region shown in DnaJ to be an essential loop for its function affected the monomer-release activity of p14. These results support the hypothesis that this p14 loop interacts with beta-tubulin in a similar fashion as DnaJ interacts with DnaK and suggest a possible role of p14 in the folding process.

Protein kinases involved in the phosphorylation of human tau protein in transfected COS-1 cells

Human tau phosphorylation has been studied in transfected COS-1 cells. Treatment with okadaic acid alters the electrophoretic mobility of human tau protein transiently expressed in transfected cells, due to an increase in the level of phosphorylation. Treatment with okadaic acid also results in an increased phosphorylation of Alzheimer's disease-type phosphoepitopes. Tau phosphorylation within COS-1 cells is partially inhibited by in vivo treatment with DRB, a protein kinase inhibitor. Double treatment of transfected cells with okadaic acid and DRB reveals that phosphorylation of tau protein at the AT8 epitope is achieved by a DRB-resistant protein kinase which is different from that responsible for tau phosphorylation at the SMI-31 epitope, which appears to be sensitive to DRB.

Tyrosine phosphorylation of focal adhesion kinase (p125FAK): regulation by cAMP and thrombin in mesangial cells

Stress fibers, composed of actin filaments, converge upon and associate with a number of proteins, including focal adhesion kinase (p125FAK), and integrin receptors to form areas of close contact between cells and the extracellular matrix referred to as focal adhesions. Treatment of mesangial cells with cAMP-elevating agents causes a loss of focal adhesions, fragmentation of stress fibers, and decreased tyrosine phosphorylation of p125FAK. Thrombin reverses these effects of cAMP, and this model can be used to address some of the cellular mechanisms involved in regulating the loss and formation of focal adhesions. This study reports the effects of cAMP and thrombin on mesangial cell shape, distribution of actin, formation of stress fibers, and tyrosine phosphorylation of p125FAK. cAMP-treated cells display a condensed cell body with slender processes that traverse the area formerly covered by the cell. Addition of thrombin to these cells restores actin filaments (stress fibers) and increases tyrosine phosphorylation of p125FAK, and the cells resume a flattened morphology, even in the continued presence of cAMP-elevating agents. Peptides that mimic the tethered ligand portion of the thrombin receptor have the same effects on cell morphology and stress fiber formation as thrombin. In selected experiments, agents that disrupt either stress fibers (cytochalasin D) or microtubules (nocodazole; Sigma Chemical, St. Louis, MO) were used to examine the role of these cytoskeletal elements in thrombin-induced restoration of focal adhesions. Cytochalasin D blocked the ability of thrombin to restore focal adhesions and phosphorylate p125FAK. The effects of nocodazole, an agent that destabilizes microtubules (but which has no known receptor), are very similar to those of thrombin. The findings discussed in this study indicate that thrombin can modulate the formation of focal adhesions. The organization of stress fibers and microtubules is apparently intimately related to the phosphorylation of p125FAK and can be modulated by soluble receptor agonists such as thrombin or via altered polymerization of microtubules.

Prevention of oral injuries

The importance of protection during various types of sports activities cannot be overemphasized. The use of mouth guards has been instrumental in preventing dental injuries. Dentists, however, must be knowledgeable in the pitfalls of these various types of protective devices.

A mutant T7 RNA polymerase as a DNA polymerase

We have identified a T7 RNA polymerase (RNAP) mutant that efficiently utilizes deoxyribonucleoside triphosphates. In vitro this mutant will synthesize RNA, DNA or 'transcripts' of mixed dNMP/rNMP composition depending on the mix of NTPs present in the synthesis reaction. The mutation is conservative, changes Tyr639 within the active site to phenylalanine and does not affect promoter specificity or overall activity. Non-conservative mutations of this tyrosine also reduce discrimination between deoxyribo- and ribonucleoside triphosphates, but these mutations also cause large activity reductions. Of 26 mutations of other residues in and around the active site examined none showed marked effects on rNTP/dNTP discrimination. Mutations of the corresponding tyrosine in DNA polymerase (DNAP) I increase miscoding, though effects on dNTP/rNTP discrimination for the DNAP I mutations have not been reported. This conserved tyrosine may therefore play a similar role in many polymerases by sensing incorrect geometry in the structure of the substrate/template/product due to inappropriate substrate structure or mismatches. T7 RNAP can use RNA templates as well as DNA templates and is capable of both primer extension and de novo initiation. The Y639F mutant retains the ability to use RNA or DNA templates. Thus this mutant can display de novo initiated or primed DNA-directed DNA polymerase, reverse transcriptase, RNA-directed RNA polymerase or DNA-directed RNA polymerase activities depending simply on the templates and substrates presented to it in the synthesis reaction.

[The role of radical surgery in the treatment of epidermoid carcinoma of the anal canal]

In order to define the role of radical surgery in the actual treatment of epidermoid carcinoma of the anal canal (ECAC), we retrospectively reviewed the charts of patients with primary ECAC, treated with radical surgery in the Hospital de Oncología, National Medical Center IMSS. We analyzed the recurrence pattern, its treatment and the contemporary literature was reviewed. From 1975 to 1990, we treated 16 patients; 13 females, 3 males, mean age was 64 years. The presurgical stage was T2, 6; T3 7; T4, 3. An abdominoperineal resection was performed in 12 patients; a posterior pelvic exenteration in 3; a total pelvic exenteration in 1. Ten patients developed surgical complications, 4 of them were major, 2 required surgical reintervention. There was no operative mortality. We obtained local tumor control in 5/16 patients (32%); the local recurrence by stage were T2, 3/6 (50%); T3, 5/7 (71%); T4, 3/3 (100%) p = 0.04. Ten of them were located at the pelvis brim and 1 was located to the central pelvis (vagina, perineum), 9 were treated with radiation therapy (RT) a mean dose of 45 Gy, only the patient with central local recurrence obtained local tumor control. Regional recurrences were as follows: T2 patients, 1/6 (16%); T3, 2/7 (28%); T4, 2/3 (66%). The 2 patients with metachronous inguinal lymph node metastases were treated with a radical groin dissection, with tumor control. In conclusion, the radical surgical treatment is associated with a low loco-regional tumor control; the pelvic tumor relapses were located at the pelvis brim and with no response to RT. With the results herein obtained and the results with other treatment modalities such as RT and its associations with chemotherapy (C) in regard to local tumor control, the actual role of the radical surgical treatment in the salvage of central pelvic relapses to primary treatment with RT or C-RT.

Binding of heat-shock protein 70 (hsp70) to tubulin

Binding of heat-shock protein (hsp70) to polymerized tubulin has been investigated by in vitro experiments. The tubulin region involved in binding to hsp70 corresponds to the carboxy-terminal residues 431-444, also involved in the association with other microtubule-associated proteins (MAPs). Additionally, the putative tubulin binding motif in the hsp70 protein contains a sequence related to the motif described for MAP1B protein.

Role of the carboxy terminal region of beta tubulin on microtubule dynamics through its interaction with the GTP phosphate binding region

The dynamic instability of microtubules depends on the GTP binding to tubulin, the rate of hydrolysis of GTP bound to tubulin molecules, at the microtubule caps, and on the affinity and exchange rate of tubulin for GTP versus GDP. It has been demonstrated that the binding of microtubule-associated proteins (MAPs) such as Tau or MAP2 notably enhances microtubule stability in vivo. These MAPs bind to the tubulin carboxy terminal domain. Consequently, an attractive hypothesis to explain the modulation of microtubule dynamics by MAPs is that the carboxy terminal domain of tubulin interacts with a region close to the GTP binding site, preventing the binding of GTP or exchange of GDP for GTP. By carrying out a combined analysis of crosslinking and limited proteolysis, an intramolecular interaction between the carboxy terminus and the tubulin region containing the GTP binding site in beta tubulin has been observed. It is proposed that this interaction modifies the binding of GTP to the tubulin beta-subunit and, therefore, affects tubulin assembly dynamics. This suggests a molecular explanation for the effect of MAPs in facilitating tubulin polymerization through the regulation of the interaction of GTP.

Sports dentistry: coming of age in the '90s

As the country becomes more health conscious, many of our patients are becoming involved in sporting activities, from organized teams to the occasional weekend warrior. As a result, the incidence of oral trauma is increasing. Dentistry today must respond to these patient's specialized needs, providing them with the quality of care they deserve. This paper discusses the prevention, diagnosis and treatment of sports-related dental trauma for the general dentist. Injury management, smokeless tobacco, mouth guard comparisons, custom mouth guard fabrication, marketing techniques and liability are presented.

Stimulation of the thrombin receptor of human glomerular mesangial cells by Ser-Phe-Leu-Leu-Arg-Asn-Pro-Asn-Asp-Lys-Tyr-Glu-Pro-Phe peptide

We have studied the effects of thrombin (alpha-thrombin) and Ser-Phe-Leu-Leu-Arg-Asn-Pro-Asn-Asp-Lys-Tyr-Glu-Pro-Phe (SFLL), a peptide agonist of the platelet thrombin receptor in cultured human mesangial cells, and find that SFLL can reproduce the biochemical and morphological effects of thrombin. Treatment of mesangial cells with cAMP-elevating agents causes fragmentation of stress fibers, loss of the vitronectin receptor from sites of focal adhesion, and produces a change in shape from a flat to a more arborized configuration. These effects are prevented by both thrombin and SFLL. Thrombin and SFLL also initiate biochemical signaling events in mesangial cells by stimulating the metabolism of phospholipids. Both thrombin and SFLL stimulate release of inositol phosphates from [3H]inositol-labeled cells, elevation of cytosolic calcium, the formation of [3H]myristic acid-labeled diacylglycerol, an increase in the mass of diacylglycerol, 32P incorporation into phospholipids, and release of unesterified [3H]arachidonic acid from cells prelabeled with [3H]arachidonic acid. When present together, the effects of SFLL and thrombin on diacylglycerol formation, arachidonic acid production, and inositol phosphate production were not additive. This suggested that SFLL and thrombin were acting on the same receptor. This was further supported by our observations that cells pretreated with SFLL and subsequently exposed to thrombin (or vice versa) did not show elevated cytosolic calcium. We also show that phospholipase D is activated by demonstrating production of radiolabeled phosphatidylethanol when cells are treated with SFLL in the presence of ethanol. These findings indicate that SFLL can be used to study the receptor-mediated effects of thrombin in mesangial cells, thereby avoiding thrombin's proteolytic actions.

Calmodulin binds to a tubulin binding site of the microtubule-associated protein tau

Previous studies have demonstrated that the microtubule-associated proteins MAP-2 and tau interact selectively with common binding domains on tubulin defined by the low-homology segments alpha (430-441) and beta (422-434). It has been also indicated that the synthetic peptide VRSKIGSTENLKHQPGGG corresponding to the first tau repetitive sequence represents a tubulin binding domain on tau. The present studies show that the calcium-binding protein calmodulin interacts with a tubulin binding site on tau defined by the second repetitive sequence VTSKCGSLGNIHHKPGGG. It was shown that both tubulin and calmodulin bind to tau peptide-Sepharose affinity column. Binding of calmodulin occurs in the presence of 1 mM Ca 2+ and it can be eluted from the column with 4 mM EGTA. These findings provide new insights into the regulation of microtubule assembly, since Ca2+/calmodulin inhibition of tubulin polymerization into microtubules could be mediated by the direct binding of calmodulin to tau, thus preventing the interaction of this latter protein with tubulin.

The tubulin-binding sequence of brain microtubule-associated proteins, tau and MAP-2, is also involved in actin binding

The interaction of actin with a synthetic peptide which corresponds to one of the repeated tubulin-binding sites present in tau and MAP-2 (microtubule-associated protein 2) proteins has been analysed. The analysis, which uses affinity chromatography of G-actin on a column containing the synthetic peptide, and the co-sedimentation and co-localization of F-actin and the peptide (as determined by immunoelectron microscopy), indicates that the part of the amino acid sequence of tau involved in the binding of tubulin is also involved in actin binding.

A subset of antibodies from the sera of patients with systemic lupus erythematosus react with vimentin and DNA

Sera from patients with systemic lupus erythematosus were tested for the simultaneous presence of antibodies to intermediate filaments (vimentin) and to DNA, using radioimmunoassay and immunofluorescence techniques. Our results indicate that 3 of 17 sera tested contain an IgM population which recognizes an antigenic determinant common to vimentin and DNA by a solid phase immunoassay.

Removal of the carboxy terminus of beta-tubulin subunit produces lateral annealing of microtubules with different orientations

1. Tubulin, lacking the carboxy terminus region of its beta subunit assembles into composite microtubule structures showing opposite polarity. 2. Since in these polymers, microtubules are laterally bound, this type of interaction could lead to the generation of microtubules with different polarities, as those found in some cellular types.

Linear growth of children with nephrotic syndrome: effect of alkylating agents

Growth velocity measurements were assessed in 12 children with steroid responsive but frequent relapsing or dependent nephrotic syndrome prior to and following treatment with either cyclophosphamide or chlorambucil and alternate day prednisone. Patients averaged 6 +/- 3 years (mean +/- SD) of age at the time of treatment. All of the patients underwent renal biopsy prior to treatment; 5 of the 12 showed mesangial proliferation; and in 10 of the 12, IgM deposits were seen within the mesangium of the glomerulus. Growth rates before treatment with the alkylating agent were 4.3 +/- 1.3 cm/y increasing to 8.7 +/- 2.5 cm/y (P less than .001) after therapy despite the relapses that occurred in 5 of the patients in the year following treatment. Short-term side effects of the treatment were minimal. The significant increase in growth associated with diminished use of steroids makes the use of alkylating agents reasonable for children with nephrosis who show signs of decreased growth velocity.

[Uropathogenic Serratia marcescens of hospital origin: analysis of the adhesion mechanism of 2 strains]

We isolated 2 Serratia marcescens strains, fim (0) and fim (-), from patients with urinary tract infection. Adhesion properties were studied by hemagglutination, response of uroepithelial cells and electron microscopy techniques. S marcescens fim (+) showed high adherence to uroepithelial cells, hemagglutination capacity and peculiar electron microscopy characteristics. All of these are absent in the fim (-) variety. The fim (+) strain was resistant to nitrofurantoin, nalidixic acid, tetracyclin, ampicillin, gentamycin, cefradine, cephotaxime and cotrimoxazole, whereas the fim (-) strain was sensitive to all. An absence of extrachromosomal DNA was demonstrated in S marcescens fim (+) suggesting that its characteristics are not coded in plasmids.

Iodination of proteins on nitrocellulose blotting paper

A procedure is described for radioiodination to a high specific activity of proteins immobilized on nitrocellulose membranes. After radioiodination, the proteins can be removed from the nitrocellulose to perform such structural analyses as proteolytic mapping. This method allows the detection of small amounts of protein recognized by immunoblotting and may be used to compare the structure of immunologically related proteins.

Diarrhea associated with rotaviruses, enterotoxigenic Escherichia coli, Campylobacter, and other agents in Costa Rican children, 1976-1981

Rotaviruses, enterotoxigenic Escherichia coli, Salmonella, Shigella, and parasites were investigated in outpatient diarrheic children, and in hospitalized diarrheic and non-diarrheic children, between January 1976 and June 1979. In outpatient cases studied within 4 days of onset of symptoms, rotaviruses were the most common agents (45.3%); E. coli heat-stable enterotoxin ranked second (13.4%); Shigella was third (8.1%); Salmonella was fourth (7.3%). In 63.2%, one or more enteric agents were detected. In hospitalized non-diarrheic children, asymptomatic shedding of pathogens was rarely observed. A later survey of outpatient diarrheic children revealed Campylobacter fetus jejuni in 8%. In 5.5 years of observation rotaviruses were endemic with excess frequency in the dry and cooler months of December and January. The excess occurrence of bacterial pathogens did not coincide with that of rotaviruses.