A Comparison of Online Self-Training and Standard Bedside Training in Lung Ultrasonography for Medical Students

PURPOSE

Point-of-care ultrasonography (POCUS) is increasingly integrated into medical education. Traditionally taught at the bedside using a hands-on approach, POCUS is limited by cost, time, faculty availability, and access to POCUS resources. With the recent transition to digitalization in medical education, the authors compare lung POCUS performance and pathology identification among medical students to examine whether using an online, self-learning lung POCUS module is noninferior to traditional bedside, faculty-led lung POCUS training.

METHOD

This study assessed the performance of 51 medical students from August to October 2021 on an elearning lung POCUS course with traditional bedside training and no training. POCUS students were scored on use of a simulator to identify pathologies, ability to identify lung ultrasonographic pathological clips, and scanning technique.

RESULTS

The elearning group had a significantly higher median (interquartile range [IQR]) total test score (15/18 [10.5-16] vs. 12/18 [9-13]; P = .03) and scanning technique score (5/5 [4-5] vs. 4/5 [3-4]; P = .03) compared with the standard curriculum group. The median (IQR) accuracy in the clip segment of the examination was 7.5 of 10 (4-9) in the self-learning group and 6 of 10 (4-7) in the standard curriculum group ( P = .18). The median (IQR) grade on the simulator segment of the examination was 2 of 3 (2-3) in the self-learning group and 2 of 3 (1-2) in the standard curriculum group ( P = .06).

CONCLUSIONS

This study suggests that self-directed elearning of lung POCUS is at least noninferior to bedside teaching and possibly even a superior method of learning lung POCUS. This teaching method POCUS is feasible for medical students to learn lung ultrasonography and has potential to complement or augment the traditional learning process or eliminate or lessen the requirement for bedside teaching by reaching a larger audience while minimizing costs and human resources.

Clinician Risk Tolerance and Rates of Admission From the Emergency Department

Importance

Much remains unknown about the extent of and factors that influence clinician-level variation in rates of admission from the emergency department (ED). In particular, emergency clinician risk tolerance is a potentially important attribute, but it is not well defined in terms of its association with the decision to admit.

Objective

To further characterize this variation in rates of admission from the ED and to determine whether clinician risk attitudes are associated with the propensity to admit.

Design, Setting, and Participants

In this observational cohort study, data were analyzed from the Massachusetts All Payer Claims Database to identify all ED visits from October 2015 through December 2017 with any form of commercial insurance or Medicaid. ED visits were then linked to treating clinicians and their risk tolerance scores obtained in a separate statewide survey to examine the association between risk tolerance and the decision to admit. Statistical analysis was performed from 2022 to 2023.

Main Outcomes and Measures

The ratio between observed and projected admission rates was computed, controlling for hospital, and then plotted against the projected admission rates to find the extent of variation. Pearson correlation coefficients were then used to examine the association between the mean projected rate of admission and the difference between actual and projected rates of admission. The consistency of clinician admission practices across a range of the most common conditions resulting in admission were then assessed to understand whether admission decisions were consistent across different conditions. Finally, an assessment was made as to whether the extent of deviation from the expected admission rates at an individual level was associated with clinician risk tolerance.

Results

The study sample included 392 676 ED visits seen by 691 emergency clinicians. Among patients seen for ED visits, 221 077 (56.3%) were female, and 236 783 (60.3%) were 45 years of age or older; 178 890 visits (46.5%) were for patients insured by Medicaid, 96 947 (25.2%) were for those with commercial insurance, 71 171 (18.5%) were Medicare Part B or Medicare Advantage, and the remaining 37 702 (9.8%) were other insurance category. Of the 691 clinicians, 429 (62.6%) were male; mean (SD) age was 46.5 (9.8) years; and 72 (10.4%) were Asian, 13 (1.9%) were Black, 577 (83.5%) were White, and 29 (4.2%) were other race. Admission rates across the clinicians included ranged from 36.3% at the 25th percentile to 48.0% at the 75th percentile (median, 42.1%). Overall, there was substantial variation in admission rates across clinicians; physicians were just as likely to overadmit or underadmit across the range of projected rates of admission (Pearson correlation coefficient, 0.046 [P = .23]). There also was weak consistency in admission rates across the most common clinical conditions, with intraclass correlations ranging from 0.09 (95% CI, 0.02-0.17) for genitourinary/syncope to 0.48 (95% CI, 0.42-0.53) for cardiac/syncope. Greater clinician risk tolerance (as measured by the Risk Tolerance Scale) was associated with a statistically significant tendency to admit less than the projected admission rate (coefficient, -0.09 [P = .04]). The other scales studied revealed no significant associations.

Conclusions and Relevance

In this cohort study of ED visits from Massachusetts, there was statistically significant variation between ED clinicians in admission rates and little consistency in admission tendencies across different conditions. Admission tendencies were minimally associated with clinician innate risk tolerance as assessed by this study's measures; further research relying on a broad range of measures of risk tolerance is needed to better understand the role of clinician attitudes toward risk in explaining practice patterns and to identify additional factors that may be associated with variation at the clinician level.

Amiodarone and pulmonary toxicity in atrial fibrillation: a nationwide Israeli study

BACKGROUND AND AIMS

Amiodarone-related interstitial lung disease (ILD) is the most severe adverse effect of amiodarone treatment. Most data on amiodarone-related ILD are derived from periods when amiodarone was given at higher doses than currently used.

METHODS

A nationwide population-based study was conducted among patients with incident atrial fibrillation (AF) between 1 December 1999 and 31 December 31 2021. Amiodarone-exposed patients were matched 1:1 with controls unexposed to amiodarone based on age, sex, ethnicity, and AF diagnosis duration. The final patient cohort included only matched pairs where amiodarone therapy was consistent throughout follow-up. Directed acyclic graphs and inverse probability treatment weighting (IPTW) modelling were used. Patients with either prior ILD or primary lung cancer (PLC) were excluded. The primary outcome was the incidence of any ILD. Secondary endpoints were death and PLC.

RESULTS

The final cohort included 6039 amiodarone-exposed patients who were matched with unexposed controls. The median age was 73.3 years, and 51.6% were women. After a mean follow-up of 4.2 years, ILD occurred in 242 (2.0%) patients. After IPTW, amiodarone exposure was not significantly associated with ILD [hazard ratio (HR): 1.45, 95% confidence interval (CI): 0.97, 2.44, P = 0.09]. There was a trivial higher relative risk of ILD among amiodarone-exposed patients between Years 2 and 8 of follow-up [maximal risk ratio (RR): 1.019]. Primary lung cancer occurred in 97 (0.8%) patients. After IPTW, amiodarone was not associated with PLC (HR: 1.18, 95% CI: 0.76, 2.08, P = 0.53). All-cause death occurred in 2185 (18.1%) patients. After IPTW, amiodarone was associated with reduced mortality risk (HR: 0.65, 95% CI: 0.60, 0.72, P < 0.001). The results were consistent across a variety of sensitivity analyses.

CONCLUSION

In a contemporary AF population, low-dose amiodarone was associated with a trend towards increased risk of ILD (15%-45%) but a clinically negligible change in absolute risk (maximum of 1.8%), no increased risk of PLC, and a lower risk of all-cause mortality.

Altered Serum Alpha1-Antitrypsin Protease Inhibition before and after Clinical Hematopoietic Stem Cell Transplantation: Association with Risk for Non-Relapse Mortality

α1-Antitrypsin (AAT), an acute-phase reactant not unsimilar to C-reactive protein (CRP), is a serine protease inhibitor that harbors tissue-protective and immunomodulatory attributes. Its concentrations appropriately increase during conditions of extensive tissue injury, and it induces immune tolerance, in part, by inhibiting the enzymatic activity of the inflammatory serine protease, proteinase 3 (PR3). Typically administered to patients with genetic AAT deficiency, AAT treatment was recently shown to improve outcomes in patients with steroid-refractory graft-versus-host disease (GVHD). GVHD represents a grave outcome of allogeneic hematopoietic stem cell transplantation (HSCT), a potentially curative intervention for hematological diseases. The procedure requires radio/chemotherapy conditioning of the prospective marrow recipient, a cytotoxic process that causes vast tissue injury and, in some formats, interferes with liver production of AAT. To date, changes in the functional profile of AAT during allogeneic HSCT, and during the cytotoxic intervention that precedes HSCT, are unknown. The present study followed 53 patients scheduled for allogeneic HSCT (trial registration NCT03188601). Serum samples were tested before and after HSCT for AAT and CRP levels and for intrinsic anti-proteolytic activity. The ex vivo response to clinical-grade AAT was tested on circulating patient leukocytes and on a human epithelial cell line treated with patient sera in a gap closure assay. According to the ex vivo experiments, circulating leukocytes responded to AAT with a favorable immune-regulated profile, and epithelial gap closure was enhanced by AAT in sera from GVHD-free patients but not in sera from patients who developed GVHD. According to serum collected prior to HSCT, non-relapse mortality was reliably predicted by combining three components: AAT and CRP levels and serum anti-proteolytic activity. Taken together, HSCT outcomes are significantly affected by the anti-proteolytic function of circulating AAT, supporting early AAT augmentation therapy for allogeneic HSCT patients.

Corrigendum: Correlation between kinetic and kinematic measures, clinical tests and subjective self-evaluation questionnaires of the affected upper limb in people after stroke

[This corrects the article DOI: 10.3389/fnins.2023.1264513.].

Correlation between kinetic and kinematic measures, clinical tests and subjective self-evaluation questionnaires of the affected upper limb in people after stroke

Introduction

Assessment of stroke recovery should include multiple sources of information in order to obtain a complete understanding of the individual's rehabilitation progress. Self-evaluation questionnaires' scores do not always correspond to the scores of commonly used clinical evaluation tools. The purpose of this study was to assess the relationship between self-evaluation questionnaires, clinical tests, and kinematic and kinetic analyses of the affected upper limb after stroke, and to determine the correlation between these measures and self-reported general function 2-4 years after the stroke.

Methods

Twenty-six subjects recovering from stroke were included in the study. Spearman's correlation coefficient was used to measure the correlation between Stroke Impact Scale (SIS), Motor activity Log (MAL), Fugl-Meyer Assessment (FMA) and Action Reach Arm Test (ARAT) scores, and kinematic and kinetic analyses. A logistic regression was used to assess the extent to which these measures may predict the participants' functional self-reported status 2-4 years post stroke.

Results

Sections regarding hand function, hand force and general ADL of the self-evaluation questionnaires correlated with kinematic variables. However, only questionnaires that focus on hand function correlated with clinical tests. Mean and maximal hand velocity had the strongest correlations with self-evaluation questionnaires and with the clinical tests, more than other kinematic variables. Self-evaluation questionnaires and clinical tests were found to be correlated with hand kinetic metrics force-to-time ratio and number of force peaks. SIS hand force domain, mean velocity and maximal velocity predicted self-reported general function 2-4 years after the stroke.

Conclusion

Self-evaluation questionnaires should be considered for wider use in the clinical evaluation of a patient's stroke recovery, since they add important information on the individual's functional status, which is not reflected in the clinical tests.

Correlates of protection for booster doses of the SARS-CoV-2 vaccine BNT162b2

Vaccination, especially with multiple doses, provides substantial population-level protection against COVID-19, but emerging variants of concern (VOC) and waning immunity represent significant risks at the individual level. Here we identify correlates of protection (COP) in a multicenter prospective study following 607 healthy individuals who received three doses of the Pfizer-BNT162b2 vaccine approximately six months prior to enrollment. We compared 242 individuals who received a fourth dose to 365 who did not. Within 90 days of enrollment, 239 individuals contracted COVID-19, 45% of the 3-dose group and 30% of the four-dose group. The fourth dose elicited a significant rise in antibody binding and neutralizing titers against multiple VOCs reducing the risk of symptomatic infection by 37% [95%CI, 15%-54%]. However, a group of individuals, characterized by low baseline titers of binding antibodies, remained susceptible to infection despite significantly increased neutralizing antibody titers upon boosting. A combination of reduced IgG levels to RBD mutants and reduced VOC-recognizing IgA antibodies represented the strongest COP in both the 3-dose group (HR = 6.34, p = 0.008) and four-dose group (HR = 8.14, p = 0.018). We validated our findings in an independent second cohort. In summary combination IgA and IgG baseline binding antibody levels may identify individuals most at risk from future infections.

The Association between Varicella Vaccination and Herpes Zoster in Children: A Semi-National Retrospective Study

Varicella vaccination in children has been performed worldwide in recent years. Despite established effectiveness, many countries still do not routinely vaccinate children against varicella, probably due to concerns about complications, such as herpes zoster infection. We aimed to compare the herpes zoster incidence in children before and after implementing the mandatory varicella vaccine in Israel in 2008. As a secondary aim, we characterized several parameters, including age, sex, and ethnic sector among herpes zoster cases, and we evaluated the complication rate to identify data relevant to the immunization status of the pediatric population. A retrospective study was conducted between 2000 and 2021, including patients aged 0-18 years old in a large cohort in southern Israel. A time series analysis and complication rates evaluations were performed in the pre- and post-vaccination eras. A total of 109.24 herpes zoster cases per 100,000 population per year were diagnosed between 2000 and 2007 (pre-vaccination era), compared to 354.71 herpes zoster cases per 100,000 population per year diagnosed between 2008 and 2021 (post-vaccination era) (p < 0.001). No change in the complication rate was documented. Thus, we concluded that there is an association between the varicella vaccine implementation program and the increase in the rate of herpes-zoster occurrence without a concurrent negative contribution to herpes zoster-related morbidity.

Perspectives of Emergency Clinicians About Medical Errors Resulting in Patient Harm or Malpractice Litigation

This cross-sectional study analyzes responses to a survey about medical error outcomes completed by emergency department attending physicians and advanced practice clinicians.

Does training make a difference? Proficiency training in transfusion guidelines and its effect on red blood cell administration

Background

Packed red blood cell (RBC) transfusion is a very common and frequently lifesaving therapeutic intervention, but a liberal transfusion policy may be associated with inferior patient outcomes. Various guidelines have been proposed to reduce the rate of unnecessary RBC transfusions. However, physicians' proficiency in such guidelines and the effect of training on RBC administration remain unknown.

Methods

We performed a questionnaire‐based assessment of physicians' knowledge of the guidelines in a tertiary hospital in Israel, followed by an analysis of RBC administration six months before and six months after training was delivered.

Results

The level of proficiency was higher among Israeli university graduates (Odds Ratio [OR] 2.59, p‐value = 0.02), internists (OR 2.8, p‐value = 0.02), and physicians beyond the step‐one residency exam (OR 3.08, p‐value = 0.02). There was no significant effect of training on the rates of RBC administration (incidence rate ratio [IRR] = 0.96 [CI 95% 0.81–1.14], p‐value = 0.655).

Conclusion

Educational intervention alone is an ineffective means of reducing the rates of RBC administration. A more complex approach is required to prevent unnecessary RBC transfusions.

Attitudes toward risk among emergency physicians and advanced practice clinicians in Massachusetts

OBJECTIVE

Risk aversion is a personality trait influential to decision making in medicine. Little is known about how emergency department (ED) clinicians differ in their attitudes toward risk taking.

METHODS

We conducted a cross-sectional survey of practicing ED clinicians (physicians and advanced practice clinicians [APCs]) in Massachusetts using the following 4 existing validated scales: the Risk-Taking Scale (RTS), Stress from Uncertainty Scale (SUS), the Fear of Malpractice Scale (FMS), and the Need for (Cognitive) Closure Scale (NCC). We used Cronbach's α to assess the reliability of each scale and performed multivariable linear regressions to analyze the association between the score for each scale and clinician characteristics.

RESULTS

Of 1458 ED clinicians recruited for participation, 1116 (76.5%) responded from 93% of acute care hospitals in Massachusetts. Each of the 4 scales demonstrated high internal consistency reliability with Cronbach's αs ranging from 0.76 to 0.92. The 4 scales also were moderately correlated with one another (0.08 to 0.54; all P < 0.05). The multivariable results demonstrated differences between physicians and APCs, with physicians showing a greater tolerance for risk or uncertainty (NCC difference, -3.58 [95% confidence interval, CI, -5.26 to -1.90]; SUS difference, -3.14 [95% CI: -4.99 to -1.29]) and a higher concern about malpractice (FMS difference, 1.14 [95% CI, 0.11-2.17]). Differences were also observed based on clinician age (a proxy for years of experience), with greater age associated with greater tolerance of risk or uncertainty (age older than 50 years compared with age 35 years and younger; NCC difference, -2.84 [95% CI, -4.69 to -1.00]; SUS difference, -4.71 [95% CI, -6,74 to -2.68]) and less concern about malpractice (FMS difference, -3.19 [95% CI, -4.31 to -2.06]). There were no appreciable differences based on sex, and there were no consistent associations between scale scores and the practice and payment characteristics assessed.

CONCLUSION

We found that risk attitudes of ED clinicians were associated with type of training (physician vs APC) and age (experience). These differences suggest one possible explanation for the observed differences in decision making.

The Impact of Racial Bias in Patient Care and Medical Education: Let's Focus on the Educator

INTRODUCTION

Racial bias in health care is well documented. Research shows the presence of racial bias among health care providers. There is a paucity of workshops focused on racial bias effects in health professions educators.

METHOD

Two to three workshops were delivered to a diverse group of clinical educators from three programs at a major academic institution. Each workshop included a brief multimedia presentation followed by a facilitated group discussion. Participants completed the online Implicit Association Test (IAT), a baseline demographic questionnaire, and a brief post-then-pre questionnaire.

RESULTS

Twenty-four faculty participated in the study (six physicians, eight nurse practitioners, 10 physician assistants). Nineteen (90%) were women, 18 (86%) were White, nine (43%) had more than 10 years of experience as educators, and seven (35%) had previously participated in a biases program. Seventeen completed the IAT. Sixteen educators agreed or strongly agreed that bias has a significant impact on patients' outcomes at the end of the workshop compared to 17 before the workshop. Seventeen educators agreed or strongly agreed that recognizing their own racial bias would positively alter their teaching practice after the workshop compared to 15 before the workshop.

DISCUSSION

This series of workshops was created to fill a gap regarding the impact of racial bias on patient outcomes, health disparities, and health professions education. The impact of racial bias in health professions education and the long-term impact of awareness and knowledge of racial bias in education are areas needing further evaluation.

Effect of oxidative stress on the biosynthesis of 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate and isoprenoids by several bacterial strains

In this study, the gram-negative bacteria Xanthomonas campestris, Xanthomonas maltophilia, and Pseudomonas putida, facultative parasites of plants and animals, were shown to accumulate 2-C-methyl-d-erythritol-2,4-cyclopyrophosphate (MEC) in response to benzyl-viologen-induced oxidative stress. Corynebacterium ammoniagenes mutants capable of accumulating MEC in the absence of an exogenous oxidative stress inducer were obtained. Isoprenoid synthesis and MEC synthesis in these and other bacteria were shown to be alternative processes, while biosynthesis of brominated polyene xanthomonadin (an antioxidant pigment of X. campestris) increased concomitantly with the accumulation of MEC.

Long-term patient self-management of oral anticoagulation

BACKGROUND

The management of oral anticoagulation is fraught with difficulties. This study assessed a new model of anticoagulation management regarding the ability, safety, and efficacy of patients to self-monitor and self-adjust the dose of their oral anticoagulants guided by a capillary whole-blood prothrombin time (PT) monitor.

METHODS

This investigation is a retrospective cohort study of 20 patients compared with 20 matched control patients receiving oral anticoagulation at a tertiary medical institution.

RESULTS

Study patients monitored their PTs 2153 times during a mean interval of 44.7 months compared with 1608 PTs in matched control patients during a mean interval of 42.5 months. Study patients made an average of 11.5 dosage changes per patient, contrasted with 22.7 changes per control patient (P < .001). The PTs in study patients were within the recommended therapeutic range in 88.6% (95% confidence interval, 87.2 to 89.9) of the determinations compared with 68.0% (95% confidence interval, 65.7 to 70.3; P < .001) of the determinations made by the matched control patients. In response to the 2153 PTs, study patients made 67 (3.1%) dosage decisions that were considered incorrect based on physician guidelines. None of these changes led to adverse outcomes. There was no significant difference in complication rates between the two groups.

CONCLUSIONS

Results from what is the first long-term study of patient self-monitoring of PTs and self-adjustment of the warfarin sodium dosage for oral anticoagulation suggest that patients can successfully measure their own PTs, adjust their own warfarin dosage, and achieve a degree of therapeutic effectiveness at least as good, if not better than patients managed in an anti-coagulation clinic. Larger, prospective, randomized trials are needed to confirm the efficacy and safety of this new approach to therapy and to assess its cost-effectiveness.

Heat treatment of Corynebacterium ammoniagenes leads to aeration dependent accumulation of 2-C-methyl-D-erythritol-2,4-cyclopyrophosphate

2-C-methyl-D-erythritol-2,4-cyclopyrophosphate (MEC) identified as a new bacterial oxidative stress substance (Ostrovsky D. et al. (1993) Biochem. J., 295, 901-902) was shown to accumulate in Corynebacterium (Brevibacterium) ammoniagenes cells aerobically cultivated in peptone-yeast extract-glucose broth on heating for 1 hour at 45 degrees C. The enzyme(s) responsible for MEC biosynthesis is evidently oxidized for activation and is completely loosing its activity on anaerobic incubation at this temperature in an hour. Salt stress or drying did not provoke the MEC biosynthesis.

Bacterial oxidative stress substance spontaneously recyclizes to form 2-methylbutane-1,2,3,4-tetraol-1,2-cyclophospho-4-phosphate

The cells of Corynebacterium (Brevibacterium) ammonia-genes cultivated in a medium supplemented with diquat or benzylviologen accumulate 2-methylbutane-1,2,3,4-tetraol-2,4- cyclopyrophosphate as revealed by 31P-NMR spectroscopy. On heating at 120 degrees C for 30 min the cells still maintain a substantial portion of this compound and acquire new cyclic phosphates characterized by 31P-NMR chemical shifts of +17.3 and +20 p.p.m. The +17.3 p.p.m. component was isolated from the preparation of the purified cyclopyrophosphate kept for some time at pH above 7 and it was shown to be 2-methylbutane-1,2,3,4-tetraol-1,2,- cyclophospho-4-phosphate on the grounds of two-dimensional NMR spectroscopy.

Bacteria and pesticides: a new aspect of interaction--involvement of a new biofactor

Positively charged hydrophobic pesticides of the dipyridyl family [diquat, paraquat, benzylviologen (BV++), etc.] were shown to provoke accumulation of 2-methylbutane-1,2,3,4-tetraol-2,4- cyclopyrophosphate in the cells Corynebacterium (Brevibacterium) ammoniagenes while neutral dipyridyls were not. Hydrophobicity was also an important factor in this phenomenon. Of the other pesticides tested, only linuron was effective. BV++ also induced biosynthesis of the compound in Rhodococcus rhodochrous, Rh.ruber, Rh.sp. (Nocardia corynebacteroides). These microorganisms as well as most of the previously identified oxidative stress activated producers of this new cyclopyrophosphate were able to synthesize free radical generating compounds. The microorganisms concerned belong mainly to the order Actinomycetales.

The ability of bacteria to synthesize a new cyclopyrophosphate correlates with their tolerance to redox-cycling drugs: on a crossroad of chemotherapy, environmental toxicology and immunobiochemical problems

Many redox-cyclers were recently shown to induce, in some bacterial species, large-scale biosynthesis of a new 2-methylbutan-1,2,3,4-tetraol-2,4-cyclopyrophosphate believed to be involved in anti-stress reactions. In the present study Mycobacterium smegmatis, Micrococcus luteus and Brevibacterium ammoniagenes were shown to begin synthesis of the new cyclopyrophosphate when cultivated in a medium containing furacilin or furadonin (widely used nitrofuran antibacterial drugs) and to maintain close to normal growth rates, whereas Staphylococcus aureus, Bacillus subtilis and Escherichia coli were inhibited by the drugs and were unable to synthesize the cyclopyrophosphate compound. Preferential binding of Mg2+ and Cd2+ with one or other phosphoryl groups of the cyclopyrophosphate, which was indicated by selective changes of 31P-NMR chemical shifts and intramolecular hydrogen bonding, is suggested as a reason for this selectivity.

Synthesis of a new organic pyrophosphate in large quantities is induced in some bacteria by oxidative stress

Brevibacterium ammoniagenes and Micrococcus luteus were shown to synthesize up to 50 mM of a novel substance, 2-methylbutan-1,2,3,4-tetraol 2,4-cyclopyrophosphate, in response to oxidative stress created by benzyl viologen and other redox mediators under aerobic conditions. The substance, which represents greater than 50% of the extractable phosphorus, is suggested to play a role as a bacterial antistressor and is thought to be a product of condensation of two molecules of phosphoenolpyruvate whose accumulation is prompted by conversion of intracellular NADPH into an oxidized form.

A new cyclopyrophosphate as a bacterial antistressor?

In a number of bacteria an unusual glycosyl pyrophosphate (31P NMR signal chemical shift at about -15 ppm) was detected when the cells were subjected to oxidative stress. This substance from Brevibacterium ammoniagenes has now been identified as 2-methyl-butan-1,2,3,4,-tetraol-2,4-cyclopyrophosphate, which is accumulated in the cell under certain conditions in concentrations of of about 50 mM. It is now suggested that this compound is the long sought after bacterial antistressor.

Interconversion of radical and nitrone forms of lysodektose--a new trisaccharide from Micrococcus lysodeikticus

Isolated from Micrococcus lysodeikticus, 6-O-(2-deoxy-2-(N-methyl)hydroxilamino-beta-D-glucopyranosyl)-alph a-alpha- trehalose (lysodektose) is oxidized by K3Fe(CN)6 in a stepwise manner to become a nitroxyl radical and a nitrone with a double bond in the fragment O-N = CH2 which could be reduced to the original hydroxylamine form with sodium borohydride. Thus derivatives of lysodektose specifically labelled with 2H and (or) 3H in the methyl group are easily obtained. When oxidized in cells poisoned with vitamin K analogues, lysodektose is transformed into nitrone concomitant with modification of its methyl group. Participation in the antioxidant defence of the bacteria is suggested for this new trisaccharide.

Migration of chick blastoderm under the vitelline membrane: the role of fibronectin

In the earliest stages of its development the chick blastoderm is a flattened disc at the surface of the yolk. It gradually increases in diameter, partially because the cells are rapidly proliferating, but also because the cells at the periphery (the margin of overgrowth) are migrating in a centrifugal direction. These cells utilize the inner surface of the vitelline membrane as their substratum. In the normal blastoderm, these cells at the edge of the spreading blastoderm are the only cells which are attached to the vitelline membrane. This investigation is concerned with the possible role played by fibronectin in the interaction between these migrating cells and the vitelline membrane. Chick blastoderms, explanted by the New (1955) technique have been treated with synthetic peptides that mimic the adhesive recognition signal of the fibronectin molecule. The pentapeptide GRGDS (containing the specific RGD cell adhesion sequence) caused the edge cells of the blastoderm to detach within minutes, and the expansion of the blastoderm was inhibited for about 4 hr. After this period there was gradual recovery and the cells reattached and spreading resumed. Examination of the margin of the blastoderm by scanning electron microscopy showed that cell processes were lost soon after treatment with GRGDS but concomitant with reattachment and the resumption of spreading, the cell processes reformed. The pentapeptide GRDGS (with the amino acids G and D inverted) produced a brief inhibition of spreading, but after an hour these blastoderms spread at the same rate as controls. Immunocytochemical staining with anti-fibronectin demonstrated that fibronectin was not only present at the interface of the edge cells and the vitelline membrane, but also between the epiblast and the hypoblast. These results indicate that tissue movement during blastoderm spreading is dependent upon fibronectin and that the specific RGD amino acid sequence, and presumably the VLA/integrin family of receptors, is involved in this embryonic morphogenetic movement.

Somitogenesis in the mouse embryo

This report describes the initiation of somitogenesis in the mouse embryo. Correlations are made with fibronectin distribution around the unsegmented mesoderm and the distribution of cytoskeletal elements within the cells as they undergo morphogenetic movements. The same temporal and topological changes in fibronectin, laminin, and cytoskeletal elements are seen in mouse somitogenesis as in the chick embryo. A notable exception is that the epithelial stage of somitogenesis in the mouse does not form a closed vesicle as it does in the chick. In the mouse the mesial portion of the forming somite does not become epithelial before the migration of sclerotomal cells.

Alpha actinin distribution and extracellular matrix products during somitogenesis and neurulation in the chick embryo

A discrete stage in two different morphogenetic processes has been examined employing fluorescently labelled alpha-actinin as a probe to localize native alpha-actinin and antibodies to localize fibronectin and collagen type I. The stage of somitogenesis examined is the transition from the compact mesenchymal somitic mass to the epithelial somitic vesicle (ie, epithelialization of the somite). The stage of neurulation examined is the transition from the relatively flat neuroepithelium to the approximation of the neural folds. Before these morphogenetic movements begin, the neuroepithelium is sitting upon a basal lamina and interstitial collagen, and the somite is surrounded by a meshwork of interstitial collagen. During both of these processes, the cells become narrowed at their apices in the region of the tissue that is becoming concave, and alpha-actinin is localized in the apices. The localization of intracellular alpha-actinin and extracellular fibronectin, and the distribution of collagen, suggest that there is a coordinated appearance and distribution of these molecules that is temporally associated with these discrete morphogenetic events.

On the role of fibronectin during the compaction stage of somitogenesis in the chick embryo

During the early stages of somitogenesis in the chick embryo the presomitic cells in the segmental plate undergo compaction. The aggregation of segmental plate cells is stimulated by fibronectin. The stimulation of segmental plate cells to aggregate and undergo compaction can be effected in isolated segmental plate cells, in isolated segmental plates, and in intact embryos removed from the yolk. The fact that the segmental plate cells react with greater vigor to cellular fibronectin than to plasma fibronectin suggests a specific molecular mechanism in the initiation of somitogenesis.

Light microscope observations on actin distribution during morphogenetic movements in the chick embryo

The cellular distribution of actin during two morphogenetic processes in the chick embryo has been observed, using a high-resolution fluorescent technique, with heavy meromyosin as a probe. These cytoskeletal elements have been implicated in all cell and tissue movements in the embryo. It is now commonly accepted that microfilaments are necessary to provide the motive force for morphogenesis. Two morphogenetic movements in the early embryo have been studied at the light microscope level. During somitogenesis, the mesenchymal segmental plate becomes transformed into a meristic series of transient epithelial vesicles. Again, actin distribution is diffuse and random before the morphogenetic event. During epithelialization, actin becomes prominent in the apical regions of the epithelial cells. Cells in the somitic epithelial vesicles, the core cells, appear to be passive participants in this process, and consequently show no distinct cellular localization of actin.

Fibronectin distribution during somitogenesis in the chick embryo

Somite formation in vertebrates is a multi-stage process. From a relatively homogeneous rod of mesenchyme, the segmental plate, somites are formed in a repeating sequence. Cell-cell adhesion has been proposed as a causal factor in somitogenesis. This led to an analysis of fibronectin in the segmental plate with respect to the initiation of somitogenesis. The pattern of fibronectin distribution can be correlated with the initiation of somitogenesis in the anterior portion of the segmental plate. Fibronectin distribution was determined using a high resolution antibody localization technique. Differences in fibronectin distribution were verified with computer-assisted image analysis. The evidence presented supports the hypothesis that an increase in cell-cell adhesion is a significant factor in the initiation of somitogenesis.

Frog lysozyme III. The effects of metamorphic inhibition on Rana pipiens lysozyme ontogeny

The inhibition of Rana pipiens metamorphosis by thiouracil altered the ontogeny of lysozyme. Certain isozymes of the enzyme remained absent. There was, nevertheless, an increase in tissue lysozyme concentration.

Renal-adrenal interrelationships in experimental hypertension

For several weeks after partial constriction of one renal artery, the fate of this "clipped" kidney seems to exert a determining influence on blood pressure. Rats that remained hypertensive throughout the experiment almost invariably had clipped kidneys averaging 0.16 to 0.22% of body weight. Below 0.1%, this kidney was usually quite atrophic, and its presence was consistent with falling or normal blood pressure. The untouched kidney in such rats was, on the average, heavier in the hypertensive than in the normotensive animals. Since the latter also had less renal tissue on the clipped side, it appears that factors leading to high blood pressure stimulated hypertrophy beyond the level provoked by renoprival factors. In rats on a high salt intake, 5 μg/day of D-aldosterone for 3 months stimulated significant true renal hypertrophy in the absence of a rise in blood pressure. Such hypertrophy was more pronounced in similar rats that had been getting 250 μg DOCA/day for 3 months but were also normotensive. Rats that developed hypertension on this latter regimen had still heavier kidneys. Renal hypertrophy appears to be a prehypertensive phenomenon which persists and can become even more pronounced in hypertension. The highest levels of renal hypertrophy were usually associated with significant adrenal hypertrophy. Endocrine functions may be involved in renal hypertrophy. This concept is discussed in relation to a phospholipid "renin inhibitor" recently isolated from dog and hog kidneys.

Chemical assay of phospholipid renin preinhibitor in canine and human blood

A phospholipid previously shown to be converted to a lysophospholipid renin inhibitor has been demonstrated in the plasma and red cells of man and the dog. This inhibitor precursor, designated preinhibitor, is chromatographically identical to the compound previously isolated from kidneys of dogs and hogs. A method for its quantitative measurement in plasma and red cells is presented. Normal dogs tested so far have an average of 119.6 µg of preinhibitor phospholipid/ml of blood; 16.3 µg of this is in the plasma. These concentrations are constant (in red cells even increased) 48 hr after bilateral nephrectomy. To assess the physiological importance of preinhibitor, it may be necessary to measure its active lyso derivative as well as the lipase(s) most directly involved in maintaining blood levels of these two phospholipids.

THE EFFECT OF ESTROGENIC PLAINT EXTRACTS ON THE UTERUS OF THE LABORATORY RAT

The effects of estrogenic substances from various plant sources and of diethylstilbestrol on uterine weight and histology of intact, ovariectomized, hypophysectomized, and hypophysectomized-ovariectomized albino rats have been studied. Unpurified and partially purified extracts of estrogenic plant material as well as chemically known estrogenic compounds brought about marked uterine responses. The absence of the hypophysis and/or the ovary did not appear to interfere with the rate or degree of uterine response. Method of administration of the extracts influenced the physiological effectiveness of a given dose. When incorporated in the diet the effect of the extract is more marked in terms of uterine response than when the same quantity is administered orally by means of a rubber catheter. The probable relationships of the various findings to infertility are discussed.

THE ESTROGEN-LIKE SUBSTANCES IN LEGUMES AND GRASSES: THE EFFECT OF ESTROGENIC PLANT EXTRACTS ON THYROID UPTAKE OF I131 IN THE LABORATORY RAT

Increased thyroid uptake of P131 was observed is intact, and ovariectomized female rats receiving daily small oral doses of red clover extract. No such consistent effect was elicited by timothy grass extracts. With the ovariectomized rats a total of 0.168 microgram of diethylstilbestrol (D.E.S.) per rat daily in two oral doses resulted in a more pronounced increase of I131 uptake than either lower or higher D.E.S. levels. A comparison of thyroid activity data and uterine weight data of the animals consuming the plant extracts or D.E.S. suggests that the estrogenic substances of forages have a milder over-all physiological effect than an equivalent weight of D.E.S. No significant thyroid stimulation was evident in the treated hypophysectomized rats although uterine enlargement was pronounced.

ESTROGEN-LIKE SUBSTANCES IN LEGUMES AND GRASSES: THE INFLUENCE OF FRACTIONATION AND ROUTE OF ADMINISTRATION ON THE ESTROGENIC ACTIVITY OF PLANT MATERIALS

The estrogenic potency of ethanolic extracts of red clover, as revealed by means of a 3-day mouse bio-assay, remained unaltered after removal of the unpalatable chlorophyl fraction. The uterine response was found to be more marked when the extract was incorporated into the basal diet, than when administered orally by catheter.