Irradiation of Sperm Tails by Laser Microbeam

1. Sea-urchin and starfish sperm tails were irradiated at pre-selected points along the flagellum and at pre-selected phases of the beat cycle by means of a pulsed ruby laser microbeam. Multiple-exposure dark-field photomicrographs were taken immediately before and after irradiation. The flagellum usually appeared to be broken at the irradiated point. 2. The portion of a flagellum between the head and the irradiated point continued for at least a few beats if its length was at least 25% of the length of the tail, and stopped immediately if it was shorter. 3. Bends already established beyond the irradiated point continued to propagate to the tip of the flagellum. Their propagation velocity generally decreased, and there were usually changes in other bend parameters. 4. No new bends ever developed beyond the irradiated point. 5. Irradiation within a bent region often completely eliminated that region

The effects of regional out-migration on job openings by occupation

This paper reports the results of two years of research on the estimation of regional occupational employment migration rates and their influence on estimates of future job openings by occupational group. The first section provides a general description of state and metropolitan area migration by occupation and other demographic variables. The descriptive statistics demonstrate that the overall level of out-migration rates and their variation among demographic and occupational groups are quite large relative to current employment estimates and estimates of future job openings that currently do not take into account regional out-migration. The second section describes the construction, and use of, estimated adjusted out-migration rates. The adjusted out-migration rates are created by using incomplete data methods to statistically combine data from the 1990 Census and the 1987 Occupational Mobility Current Population Survey. This hybrid data set contains complete information on occupational migration and mobility and allows us to isolate the out-migration rate that reflects changes in state-of-residence but not changes in occupation. These adjusted rates eliminate potential double counting that would be introduced using unadjusted occupational out-migration rates. This application of incomplete data methods is "tested" by generating a set of adjusted migration rates for a region of the United States and applying these rates to estimates of base year regional occupation employment to produce a set of estimated job openings that take into account regional out-migration. The results show that the total number of estimated job openings by occupation have to be revised significantly upwards when out-migration is taken into account.

Kidney function assessment in the critically ill child: is it time to leave creatinine behind?

The accurate diagnosis of acute kidney injury (AKI) is especially problematic in critically ill patients in whom renal function is in an unsteady state, rendering creatinine-based baseline assessment measures of renal function potentially inadequate. Herrero-Morin and colleagues performed a cross-sectional analysis of the ability of cystatin C and β2 microglobulin to reflect creatinine clearance in pediatric patients with AKI. The aim of this commentary is to review the current state of AKI clinical and translational research in the light of the results presented in that study

Consensus-based recommendations on priority activities to address acute kidney injury in children: A modified Delphi consensus statement

Importance: Increasing evidence indicates that acute kidney injury (AKI) occurs frequently in children and young adults and is associated with poor short-term and long-term outcomes. Guidance is required to focus efforts related to expansion of pediatric AKI knowledge. Objective: To develop expert-driven pediatric specific recommendations on needed AKI research, education, practice, and advocacy. Evidence Review: At the 26th Acute Disease Quality Initiative meeting conducted in November 2021 by 47 multiprofessional international experts in general pediatrics, nephrology, and critical care, the panel focused on 6 areas: (1) epidemiology; (2) diagnostics; (3) fluid overload; (4) kidney support therapies; (5) biology, pharmacology, and nutrition; and (6) education and advocacy. An objective scientific review and distillation of literature through September 2021 was performed of (1) epidemiology, (2) risk assessment and diagnosis, (3) fluid assessment, (4) kidney support and extracorporeal therapies, (5) pathobiology, nutrition, and pharmacology, and (6) education and advocacy. Using an established modified Delphi process based on existing data, workgroups derived consensus statements with recommendations. Findings: The meeting developed 12 consensus statements and 29 research recommendations. Principal suggestions were to address gaps of knowledge by including data from varying socioeconomic groups, broadening definition of AKI phenotypes, adjudicating fluid balance by disease severity, integrating biopathology of child growth and development, and partnering with families and communities in AKI advocacy. Conclusions and Relevance: Existing evidence across observational study supports further efforts to increase knowledge related to AKI in childhood. Significant gaps of knowledge may be addressed by focused efforts

Acute kidney injury in critically ill newborns: What do we know? What do we need to learn?

Outcomes in critically ill neonates have improved over the past three decades, yet high residual mortality and morbidity rates exist. Acute kidney injury (AKI) is not just an innocent by-stander in the critically ill patient. Research on incidence and outcomes of AKI in the critically ill neonatal population is scarce. The objective of this publication is to (a) review original articles on the short- and long-term outcomes after neonatal AKI, (b) highlight key articles on adults and children with AKI in order to demonstrate how such insights might be applied to neonates, and (c) suggest clinical research studies to fill the gaps in our understanding of neonatal AKI. To date, observational studies suggest high rates of AKI and poor outcomes in critically ill neonates. Neonates with AKI are at risk of developing chronic kidney disease and hypertension. Large prospective studies are needed to test definitions and to better understand risk factors, incidence, independent outcomes, and mechanisms that lead to poor short- and long-term outcomes. Early biomarkers of AKI need to be explored in critically ill neonates. Infants with AKI need to be followed for sequelae after AKI

Local Activation and Inactivation Experiments of Flagella

The mechanisms of flagellar movement were investigated by studying the ability of various regions of a flagellum to initiate bends, and to propagate bends independently of activities in other regions. Two experimental approaches were used: the establishment of an artificial gradient of ATP along a flagellum, and the inactivation of a small region of a flagellum by localized irradiation. Flagella of the spermatozoa of sea urchins and a few other marine invertebrates were used in this study. Glycerinated flagella were activated by ATP gradients established by means of diffusion from the tips of micropipettes. These gradients could be made broad enough to produce a gradual decrease in ATP concentration along the entire flagellum, or narrow enough to supply ATP to only part of the flagellum. Localized supply of ATP to regions of the flagell11m other than the basal end produced no beating. Beating properties along the flagellum appeared quite sensitive to ATP concentration at the basal end, but rather insensitive to ATP concentration at other points, and centering a gradient about points other than the basal end did not cause beating to start at those points. Small regions of flagella were irradiated at preselected phases of beating by means of a pulsed ruby laser microbeam. Multiple-exposure dark field photographs of the spermatozoa were taken immediately before and after irradiation. The region of a flagellum between the head and the irradiated point continued beating for at least a few beats if that region was at least a quarter of the length of the tail, and stopped immediately if it was shorter. Bends which were already established beyond the irradiated point continued to the tip, but showed a variety of changes in their properties. No new bends were formed in this region. Irradiation within a bent region caused that region to straighten immediately. These experiments indicate that the basal end of the flagellum is necessary for bend initiation, and largely responsible for the determination of wave properties. Although a portion of a flagellum can independently propagate established bends, the bend properties at any point are influenced by activities along the rest of the flagellum. The relevance of these observations to current models of flagellar beating is discussed.</p