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Background: There is strong evidence supporting using the Lasater Clinical Judgment Rubric (LCJR) for scoring learners' clinical judgment during in-person simulation performance and clinical experience reflections. However, a gap exists for using LCJR to evaluate clinical judgment after observing asynchronous simulation., Objective: We aimed to determine the reliability, feasibility, and usability of LCJR for scoring learners' written reflections after observing expert-modeled asynchronous simulation videos., Design/setting/participants: We used a one-group, descriptive design and sampled pre-licensure, junior-level bachelor's learners from the Southwestern United States., Methods: Participants observed eight expert-modeled asynchronous simulation videos over one semester and provided written responses to clinical judgment prompts. We scored clinical judgment using LCJR. We studied reliability by measuring internal consistency of 11 clinical judgment prompts and interrater reliability with two raters. This study also investigated feasibility and usability of the asynchronous simulation learning activity using descriptive statistics. Feasibility included time learners spent completing written responses and time raters spent evaluating written responses. Learners reported usability perceptions using an instructor-developed survey., Results: Sixty-three learners completed 504 written responses to clinical judgment prompts. Cohen's kappa ranged from 0.34 to 0.86 with a cumulative κ = 0.58. Gwet's AC ranged from 0.48 to 0.90, with a cumulative AC = 0.74. Cronbach's alpha was from 0.51 to 0.72. Learners spent on average 28.32 ± 12.99 min per expert-modeling video observation. Raters spent on average 4.85 ± 1.34 min evaluating written responses for each participant. Learners reported the asynchronous learning activity was usable., Conclusions: Nurse educators can reliably use LCJR for scoring learners' clinical judgment after observing asynchronous expert-modeled simulation. Logistically, learners complete the reflective learning activity and faculty use LCJR to measure clinical judgment in feasible time. Further, participants perceived the asynchronous learning activity usable. Nurse educators should utilize this learning activity for evaluating and tracking observer clinical judgment development., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Multiple-patient simulation (MPS) allows nursing students to develop leadership skills. Limited research examining student outcomes following MPS exists., Purpose: This pilot study investigated the impact of MPS on (1) anxiety with transition to practice, (2) anxiety with clinical decision-making, (3) self-confidence with clinical decision-making, and (4) perceptions about MPS as a learning strategy., Methods: Twenty-two senior baccalaureate nursing students participated in this 2-group mixed-methods study. Data were collected before and after a leadership course using the State-Trait Anxiety Inventory, Nursing Anxiety and Self-Confidence with Clinical Decision-Making Scale, and a researcher-developed perceptions survey., Results: Self-confidence with clinical decision-making significantly increased for all participants regardless of group assignment. Anxiety and anxiety with clinical decision-making decreased without significant changes. No significant differences were found between groups. Qualitative findings yielded 3 themes: preparation for clinical practice, overcoming anxiety, and confidence., Conclusion: Research investigating additional student outcomes after MPS with larger, more diverse samples is needed., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

The objective of this study was to explore associations between allegations of malpractice and the severity of the alleged malpractice injury. The public-use data file of the National Practitioner Data Bank was used to identify 34,042 dentist malpractice reports from January 1, 2010, through December 31, 2020. Univariate descriptive analysis was conducted to identify frequencies of malpractice allegations when classified by the severity of the alleged malpractice injury, practitioner graduation year, and year of original report processing. Ordinal logistic regression analyses were conducted to explore associations between the malpractice allegation type and the severity of the alleged malpractice injury. A total of 15,183 valid reports were used in the analysis. Compared with treatment-related allegations, a surgery related allegation proved 5.3 times more likely to result in minor permanent injury; a diagnosis-related allegation was 6.5 times more likely to result in significant permanent injury and 10.4 times more likely to result in major permanent injury; and an anesthesia-related allegation was 6.2 times more likely to result in major permanent injury. The confounding variable of graduation year proved significant with respect to major temporary and minor permanent injury. As the allegation group advanced from diagnosis-related to anesthesia-, treatment-, and surgery-related allegations, the odds of a higher severity of injury did not increase. Establishing a proper diagnosis and developing a treatment plan to manage the anticipated complications of the procedure to be performed are critical to a successful outcome.

A commitment on the part of dentists to provide dental care to pregnant patients may contribute to alleviating the burden of oral disease experienced in this population. To assess barriers to providing dental care for pregnant patients, a survey instrument was developed and distributed to 472 Alabama Academy of General Dentistry members. Descriptive analyses were conducted to assess dental care practices, self-reported competence, and barriers to providing dental care. Bivariate analyses were conducted to determine whether dentists with and without residency training displayed differences in self-reported competence and dental care practice models. A total of 82 dentists completed the survey, yielding a response rate of 17.3%. Of the respondents, 93.9% reported providing dental care to pregnant patients in the past year. Lack of education and/or training was the most frequently identified barrier (41.5%) to the provision of care. Statistically significant associations were found between self-reported competence and residency training (χ 2 = 4; P = 0.034; Φ = 0.235). Residency training may influence dentists' self-reported competence in providing care to pregnant patients. Dentists who did not receive residency training appeared more likely to report competence in their ability to provide such care. Most respondents reported providing dental care to pregnant patients, but only 40.6% of the respondents to the 2015 Alabama Pregnancy Risk Assessment Monitoring System (PRAMS) survey reported receiving a dental cleaning during pregnancy. Implementing systems to connect these patients with dentists may increase the receipt of care among this group.

Background: Simulation based learning experiences help nurses gain skills necessary for independent practice. However, increased cognitive load placed on learners in simulation may affect learning outcomes., Objectives: The purpose of this integrative review was to synthesize what is known about nurses' cognitive load in simulation and summarize measurement approaches., Data Sources: A search of CINAHL, Medline, ProQuest Nursing and Allied Health, and ERIC databases was limited to peer-reviewed studies published after 2006 in the English language, using the key words nurse, simulation, and cognitive load., Review Methods: Whittemore and Knafl's (2005) integrative review method was used. Studies investigating advanced practice nurses or interprofessional teams were excluded., Results: Database and reference lists searches identified a total of 3077 records, and 20 met inclusion criteria. Simulation fidelity, time pressure, dual-tasking, interruptions, task complexity, distractions, and mismatched simulation objectives to learner ability increase nurses' cognitive load. However, past experience, pre-briefing, repeated scenarios, and worked-out modeling optimize cognitive load. Subjective and objective cognitive load measures help researchers understand cognitive load and define its relationship with other variables., Conclusions: Simulation impacts nurses' cognitive load. Varying simulation designs to optimize cognitive load will improve learning outcomes. Future nursing simulation research should utilize well-validated cognitive load measures and measure cognitive load alongside other variables to further understand how cognitive load affects simulation outcomes., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Simulation is an integral component of undergraduate nursing education because it allows for a safe, timely, and prescriptive approach to meet learning objectives at the levels of individual simulations, courses, and academic programs. This review of the literature provides an overview of steps taken to move simulation forward in undergraduate nursing education, and it highlights educational theories, research, best practices, and policy statements underpinning modern nursing simulation. This chapter outlines simulation and curriculum integration approaches and provides examples of participant, course, and program outcomes., (© Copyright 2021 Springer Publishing Company, LLC.)

Background: The majority of tasks nurses complete in acute care settings are time-sensitive. Due to complex patient needs, nurses' multitasking behavior is of growing importance. Situations involving multitasking behavior typically require nurses to switch their attention among multiple tasks and patients in a rapid fashion. Research suggests temporal individual differences such as time urgency, polychronicity, and time perspective influence decision-making. The factors suggest that balanced time perspective may facilitate multitasking. Given novice nurses commit errors related to multitasking, we evaluated the relationship between temporal individual differences, cognitive workload, and multitasking behaviors in a simulation setting., Methods: A one-group repeated measures design was used to evaluate the relationship between multitasking, demographic factors, cognitive workload, and temporal individual differences. One hundred sixty fourth-year, prelicensure nursing students independently completed two 45-min multiple patients simulations involving care of three interactive patient simulators. Participants completed the Multitasking Preference Inventory, Time Perspective Inventory, Experiences of Time survey, and Time Urgency Scale before simulation. A summary Creighton Simulation Evaluation Instrument score was used to represent multitasking. Participants completed the Task Load Index to represent cognitive workload. We calculated deviation from balanced time perspective and measured its correlation with multitasking. Regression models calculated how much variance deviation from balanced time perspective, demographic factors, and cognitive workload contributed to multitasking., Results: Standardized test scores were more predictive of multitasking than deviation from balanced time perspective (β = 0.19, t = 2.48, p = 0.0142). As deviation from balanced time perspective increased, multitasking behaviors decreased (r = - 0.17), participants reported a higher sense of urgency (r = 0.39), and they had more frustration after simulation (r = 0.22). Deviation from balanced time perspective did not influence cognitive workload., Conclusions: Nursing students who demonstrate multitasking behaviors tend to have a more balanced time perspective. Knowing students' deviation from balanced time perspective may help educators anticipate who will need more assistance with multitasking in simulation. Nursing students frequently wait until just before graduation to provide care for multiple patients; including mention of deviation from balanced time perspective in simulation preparation may help senior nursing students become more self-aware and ultimately improve behavioral performance.

General practice is arguably the ideal setting to initiate advance care planning (ACP), but there are many barriers. This pilot study was designed to assess the feasibility, acceptability and perceived utility of a nurse-facilitated screening interview to initiate ACP with older patients in general practice. Patients were recruited from four general practices in Sydney, Australia. General practice nurses administered the ACP screening interview during routine health assessments. Patients and nurses completed a follow-up questionnaire consisting of questions with Likert responses, as well as open-ended questions. Descriptive statistics and content analysis were used to analyse the data. Twenty-four patients participated; 17 completed the follow-up questionnaire. All patients found the ACP screening interview useful and most felt it would encourage them to discuss their wishes further with their family and general practitioner. Several patients were prompted to consider legally appointing their preferred substitute decision-maker. All six participating nurses found the screening interview tool useful for initiating discussions about ACP and substitute decision-making. This nurse facilitated screening tool provides a simple, acceptable and feasible approach to introducing ACP to older general practice patients during routine health assessments.

Aim: The purpose of the study was to determine best practices for multiple-patient simulation (MPS) preparation and frequency to improve behavioral performance in nursing students., Background: MPS provides a safe environment for novice nurses to practice priority setting, delegation, and multitasking, but evidence for best practices is needed., Method: A multisite, blinded, randomized trial was conducted to evaluate the effect of three simulation preparation methods (expert modeling, voice-over PowerPoint, and reading assignments) on students' competence and self-efficacy for providing care to multiple patients in the simulation lab. Participants (n = 73) were enrolled in capstone clinical courses at two schools of nursing., Results: Though there was no difference in raw change in competence score among the study groups, there was a statistically significant difference in pretest and posttest scores. The change in self-efficacy did not correlate with the change in competence., Conclusion: These findings will help educators understand how novice nurses benefit from repeated MPS activities.

This study examined the influence of three simulation preparation methods (expert modeling/intervention, voice-over PowerPoint/active control, and reading assignments/passive control) on improving novice nurses' competence and self-efficacy for providing care to multiple simulated patients. Both competence and self-efficacy were measured at baseline and following a five-week intervention. Twenty senior pre-licensure nursing students participated in the trial. One-way ANOVAs and parametric/nonparametric correlations were used. Voice-over PowerPoint and expert modeling resulted in greater improvements in self-efficacy compared with traditional reading assignments as simulation preparation. However, there was no relationship between change in competence and self-efficacy over time.

Due to today's complex needs of hospitalized patients, nurses' competence and strategies to improve competence are of growing importance. Simulation is commonly used to influence competence, but little evidence exists for comparing how presimulation assignments influence competence. A randomized control trial was used to compare the efficacy of three simulation preparation methods (expert modeling/intervention, voice-over PowerPoint/active control, and reading assignments/passive control) on improving competence for providing care to multiple patients among senior undergraduate novice nurses. Competence was measured at two time points (baseline and following a 5-week intervention) by two blinded raters using the Creighton Simulation Evaluation Instrument. Twenty novice nurses participated in the trial. No significant differences were noted in raw improvements in competence among the three groups, but the expert modeling (Cohen's d=0.413) and voice-over PowerPoint methods (Cohen's d=0.226) resulted in greater improvements in competence, compared with the passive control., (Copyright 2014, SLACK Incorporated.)

The influence of simulation on self-efficacy for novice nurses has been reported inconsistently in the literature. Effect sizes across studies were synthesized using random-effects meta-analyses. Simulation improved self-efficacy in one-group, pretest-posttest studies (Hedge's g=1.21, 95% CI [0.63, 1.78]; p<0.001). Simulation also was favored over control teaching interventions in improving self-efficacy in studies with experimental designs (Hedge's g=0.27, 95% CI [0.1, 0.44]; p=0.002). In nonexperimental designs, consistent conclusions about the influence of simulation were tempered by significant between-study differences in effects. Simulation is effective at increasing self-efficacy among novice nurses, compared with traditional control groups., (Copyright 2014, SLACK Incorporated.)

Background: In 2006, the National League for Nursing published three measures related to novice nurses' beliefs about self-confidence, scenario design, and educational practices associated with simulation. Despite the extensive use of these measures, little is known about their reliability and validity., Methods: The psychometric properties of the Student Satisfaction and Self-Confidence in Learning Scale, Simulation Design Scale, and Educational Practices Questionnaire were studied among a sample of 2200 surveys completed by novice nurses from a liberal arts university in the southern United States. Psychometric tests included item analysis, confirmatory and exploratory factor analyses in randomly-split subsamples, concordant and discordant validity, and internal consistency., Results: All three measures have sufficient reliability and validity to be used in education research. There is room for improvement in content validity with the Student Satisfaction and Self-Confidence in Learning and Simulation Design Scale., Conclusion: This work provides robust evidence to ensure that judgments made about self-confidence after simulation, simulation design and educational practices are valid and reliable., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Beta-blockers are currently contraindicated in asthma because their acute administration may be associated with worsening bronchospasm. However, their effects and safety with their chronic administration are not well evaluated. The rationale for this pilot study was based on the paradigm shift that was observed with the use of beta-blockers in congestive heart failure, which once contraindicated because of their acute detrimental effects, have now been shown to reduce mortality with their chronic use. We hypothesized that certain beta-blockers may also be safe and useful in chronic asthma therapy. In this prospective, open-label, pilot study, we evaluated the safety and effects of escalating doses of the beta-blocker, nadolol, administered over 9 weeks to 10 subjects with mild asthma. Dose escalation was performed on a weekly basis based on pre-determined safety, lung function, asthma control and hemodynamic parameters. The primary objective was to evaluate safety and secondary objectives were to evaluate effects on airway hyperresponsiveness, and indices of respiratory function. The escalating administration of nadolol was well tolerated. In 8 out of the 10 subjects, 9 weeks of nadolol treatment produced a significant, dose-dependent increase in PC20 that reached 2.1 doubling doses at 40 mg (P<0.0042). However, there was also a dose-independent 5% reduction in mean FEV1 over the study period (P<0.01). We conclude that in most patients with mild asthma, the dose-escalating administration of the beta-blocker, nadolol, is well tolerated and may have beneficial effects on airway hyperresponsiveness. Our findings warrant further testing in future larger trials.

Recent evidence suggests that sickness behaviors following lipopolysaccharide (LPS)-treatment may be modulated by environmental factors such as the light-dark (LD) cycle. The present study characterized LPS-induced hypoactivity and behavioral tolerance development across individual phases of the light-dark cycle and the transitions between phases. On days 1, 4 and 7, male rats were treated with LPS (200microg/kg i.p.) or saline 30min prior to the onset of either the dark period (dark-tested group) or the light period (light-tested group). Following treatment, rats were placed in non-novel automated open-fields where various aspects of locomotor activity were monitored for 16h. On day 1, LPS-treated rats in both the dark and light tested groups showed significant hypoactivity. However, temporal differences in the onset of hypoactivity were observed between the groups. In dark tested animals significant hypoactivity started 60min after LPS treatment and continued until the light period when hypoactivity was diminished. In contrast, the light tested LPS-treated animals did not exhibit a prolonged period of hypoactivity until the transition between the light and dark periods, 750min following LPS injection. On days 4 and 7, light tested animals showed complete tolerance to LPS as evidenced by the absence of significant activity reductions, whereas dark tested animals continued to show significant periods of hypoactivity. These results indicate that there are day-night differences in both the initial LPS-induced hypoactivity response as well as behavioral tolerance development. The rate of tolerance development to LPS may be a critical factor to survival and the prevention of sepsis, as organisms are repeatedly exposed to pathogens across the life cycle.

Clinical observations suggest that certain gut and dietary factors may transiently worsen symptoms in autism spectrum disorders (ASD), epilepsy and some inheritable metabolic disorders. Propionic acid (PPA) is a short chain fatty acid and an important intermediate of cellular metabolism. PPA is also a by-product of a subpopulation of human gut enterobacteria and is a common food preservative. We examined the behavioural, electrophysiological, neuropathological, and biochemical effects of treatment with PPA and related compounds in adult rats. Intraventricular infusions of PPA produced reversible repetitive dystonic behaviours, hyperactivity, turning behaviour, retropulsion, caudate spiking, and the progressive development of limbic kindled seizures, suggesting that this compound has central effects. Biochemical analyses of brain homogenates from PPA treated rats showed an increase in oxidative stress markers (e.g., lipid peroxidation and protein carbonylation) and glutathione S-transferase activity coupled with a decrease in glutathione and glutathione peroxidase activity. Neurohistological examinations of hippocampus and adjacent white matter (external capsule) of PPA treated rats revealed increased reactive astrogliosis (GFAP immunoreactivity) and activated microglia (CD68 immunoreactivity) suggestive of a neuroinflammatory process. This was coupled with a lack of cytotoxicity (cell counts, cleaved caspase 3' immunoreactivity), and an increase in phosphorylated CREB immunoreactivity. We propose that some types of autism may be partial forms of genetically inherited or acquired disorders involving altered PPA metabolism. Thus, intraventricular administration of PPA in rats may provide a means to model some aspects of human ASD in rats.

Rationale: Although the behavioral effects of systemic injection of lipopolysaccharide (LPS) have been extensively investigated, the modulation of these effects by natural environmental factors has received little attention., Objectives: The present study investigated whether or not locomotor activity reductions and the development of behavioral tolerance in response to LPS treatment would occur to the same degree if male and female rats were treated with LPS at four distinct time points across the light-dark (LD) cycle., Methods: On day 1, male and female rats were injected with either LPS (200 microg/kg IP) or saline at light onset (0400 hours), 2 h into light period (0600 hours), at dark onset (1600 hours) or 2 h into the dark period (1800 hours). Two hours after injection, rats were placed in non-novel, automated open-fields and locomotor activity was assessed. The development of behavioral tolerance to LPS was evaluated three days later (day 4) using the same procedure., Results: On day 1, LPS-treated animals displayed robust activity decrements during the light period with males displaying greater reductions than females. During the dark period, LPS-treated animals showed a similar hypoactivity response. After LPS treatment on day 4, all rats exhibited some behavioral tolerance to LPS. Rats given LPS treatment at light onset and during the dark period showed complete tolerance development while LPS-treated rats during the light phase at dark onset showed incomplete tolerance, still displaying significant reductions in some activity variables., Conclusions: It appears that the magnitude of hypoactivity and the development of behavioral tolerance in response to LPS depend on the phase of the LD cycle during which it is administered.

The RecA homolog, RAD51, performs a central role in catalyzing the DNA strand exchange event of meiotic recombination. During meiosis, RAD51 complexes develop on pairing chromosomes and then most disappear upon synapsis. In the maize meiotic mutant desynaptic2 (dsy2), homologous chromosome pairing and recombination are reduced by ~70% in male meiosis. Fluorescent in situ hybridization studies demonstrate that a normal telomere bouquet develops but the pairing of a representative gene locus is still only 25%. Chromosome synapsis is aberrant as exemplified by unsynapsed regions of the chromosomes. In the mutant, we observed unusual RAD51 structures during chromosome pairing. Instead of spherical single and double RAD51 structures, we saw long thin filaments that extended along or around a single chromosome or stretched between two widely separated chromosomes. Mapping with simple sequence repeat (SSR) markers places the dsy2 gene to near the centromere on chromosome 5, therefore it is not an allele of rad51. Thus, the normal dsy2 gene product is required for both homologous chromosome synapsis and proper RAD51 filament behavior when chromosomes pair.

An open question in meiosis is whether the Rad51 recombination protein functions solely in meiotic recombination or whether it is also involved in the chromosome homology search. To address this question, we have performed three-dimensional high-resolution immunofluorescence microscopy to visualize native Rad51 structures in maize male meiocytes. Maize has two closely related RAD51 genes that are expressed at low levels in differentiated tissues and at higher levels in mitotic and meiotic tissues. Cells and nuclei were specially fixed and embedded in polyacrylamide to maintain both native chromosome structure and the three dimensionality of the specimens. Analysis of Rad51 in maize meiocytes revealed that when chromosomes condense during leptotene, Rad51 is diffuse within the nucleus. Rad51 foci form on the chromosomes at the beginning of zygotene and rise to approximately 500 per nucleus by mid-zygotene when chromosomes are pairing and synapsing. During chromosome pairing, we consistently found two contiguous Rad51 foci on paired chromosomes. These paired foci may identify the sites where DNA sequence homology is being compared. During pachytene, the number of Rad51 foci drops to seven to 22 per nucleus. This higher number corresponds approximately to the number of chiasmata in maize meiosis. These observations are consistent with a role for Rad51 in the homology search phase of chromosome pairing in addition to its known role in meiotic recombination.

The integration of chlorophyll a/b-binding (LHCP) polypeptides and the translocation of the 33-kD oxygen-evolving enhancer protein (OEE33) have been previously shown to occur in chloroplast extracts containing stroma, thylakoids, ATP, and MgCl2. We have re-examined the nucleotide requirement for these two reactions using stromal extract and translation products depleted of low molecular weight compounds. LHCP integration activity was up to 10-fold higher when assayed with GTP compared with ATP, CTP, or UTP. A combination of ATP and GTP supported less LHCP integration activity than GTP alone, suggesting that GTP meets the entire nucleotide requirement. Nonhydrolyzable analogs of GTP were inhibitory, consistent with the idea that GTP hydrolysis is required for integration activity. Periodate-oxidized GTP (GTPox) also inhibited the integration reaction when present during the assay. Pretreatment of stroma with GTPox followed by GTPox removal inhibited integration activity, whereas pretreatment of thylakoids had no effect. We interpret this to mean that a GTP-binding protein involved in integration is localized in the stroma. Translocation of OEE33 was more efficient with ATP than with GTP, and the combination of both nucleotides was not additive. Our data implicate the involvement of a GTPase in LHCP integration but not in the translocation of OEE33.

By screening an Arabidopsis expression library with an antiserum against chloroplast envelope proteins, we have isolated a partial cDNA with an open reading frame that encodes a polypeptide similar to P-type cation-transporting ATPases. The corresponding genomic clone was isolated and the complete coding sequence was deduced after identification and mapping of introns. The gene has been designated PEA1 (plastid envelope ATPase) and the predicted polypeptide PEA1p. PEA1p has 946 amino acids and a molecular mass of 104 kDa. This protein is 40-44% identical to various mammalian plasma membrane Ca(2+)-ATPases but lacks the C-terminal calmodulin binding domain present in the mammalian polypeptides. When aligned with mammalian plasma membrane Ca(2+)-ATPases, PEA1p has a 70- to 80-amino acid N-terminal region that extends beyond the N terminus of these enzymes. This extension has some similarity to the transit peptide of the plastid envelope phosphate translocator and may function to target the protein to the plastid. Antibodies raised against a portion of PEA1p recognize a single 90- to 95-kDa polypeptide in chloroplast inner envelope preparations. Transcript abundance as determined by RNase protection was found to be 7- to 9-fold higher in roots than in leaves. Possible roles for a plastid envelope calcium pump are suggested.

Proteins and RNAs homologous to components of the eukaryotic signal recognition particle (SRP) have been identified in a number of prokaryotic organisms. Here we report the isolation of an Arabidopsis thaliana cDNA, FFC (fifty-four chloroplast homologue), that encodes a chloroplast protein (54CP) homologous to the 54-kDa subunit of the signal recognition particle. 54CP shares 27% identity with mammalian SRP54 and 44% identity with the Escherichia coli ffh gene product suggesting a prokaryotic origin for this gene. FFC is a nuclear gene encoding a 62-kDa cytoplasmically synthesized precursor that is capable of being imported into isolated chloroplasts and processed to a 53-kDa stromal polypeptide. Antibodies generated against a portion of 54CP recognize an endogenous 53-kDa chloroplast protein that sediments at 4 S and 70 S, the latter form may be associated with ribosomes. The FFC transcript is most abundant in green shoot tissue whereas etiolated buds and roots have transcript levels about 30 and 10%, respectively, relative to light grown green shoots. By analogy with the eukaryotic signal recognition particle which targets secretory proteins to the endoplasmic reticulum, it is speculated that 54CP may target chloroplast proteins to either the thylakoid or envelope membranes.

A cDNA clone (pTE-83) encoding a protein (CNX1p) related to the microsomal Ca(2+)-binding protein, calnexin, was isolated from an Arabidopsis thaliana expression library. Southern and Northern hybridization indicated that CNX1 is a single-copy gene encoding a message of 1900 nucleotides. The open reading frame encodes a polypeptide with 530 amino acids, a molecular mass of 60.5 kDa, and overall 48% identity to dog calnexin. Both animal calnexin and CNX1p contain a large luminal domain followed by a single potential membrane-spanning domain near the C terminus and a small C-terminal domain exposed to the cytoplasm. The in vitro translation product from the cloned cDNA yielded a polypeptide of 67 kDa that was co-translationally imported into dog microsomes and processed to a 64-kDa product. Antibodies generated against the C-terminal half of the protein cross-react with an identically sized protein present in the microsomal fraction from Arabidopsis. Both the imported and native proteins are cleaved by trypsin to a 59-kDa product indicating that the gene product was indeed correctly processed and translocated into dog microsomes and that the membrane topology of CNX1p resembles that of dog calnexin. The presence of a calnexin-like protein within the plant kingdom indicates that this protein is widespread and involved in processes fundamental to all eukaryotes.

A disease in mink has been discovered that has many of the features of collagen diseases in man. Affected animals suffer from wasting with leukopenia and thrombocytopenia as well as plasma cell infiltration, hypergammaglobulinemia, glomerulonephritis, arteritis and amyloidosis. Cell-free filtrates and ultracentrifugates from diseased animals induced the disease in normal mink, and aleutian genotypes were unusually susceptible to infection. This genotype was characterized by abnormal lysosomal structures in all the granule-forming cells, resembling the Chediak-Higashi syndrome of man. Anti-gamma-globulin factors similar to human rheumatoid factors were reported, although tests for antibodies such as ANF and LE factors have been negative. Arteritis and glomerulonephritis lesions stained positively for gamma-globulin, and Coombs-type sensitized red cells have been detected in the majority of affected mink. Some mink develop a monodispersion of hypergammaglobulinemia resembling the serum protein changes in human myeloma. These studies highlight genetic, immunological and microbiological causative factors in a mink disorder resembling human collagen disease.