Riding the waves from epidemic to endemic: Viral mutations, immunological change and policy responses.

Nonpharmaceutical interventions (NPI) are an important tool for countering pandemics such as COVID-19. Some are cheap; others disrupt economic, educational, and social activity. The latter force governments to balance the health benefits of reduced infection and death against broader lockdown-induced societal costs. A literature has developed modeling how to optimally adjust lockdown intensity as an epidemic evolves. This paper extends that literature by augmenting the classic SIR model with additional states and flows capturing decay over time in vaccine-conferred immunity, the possibility that mutations create variants that erode immunity, and that protection against infection erodes faster than protecting against severe illness. As in past models, we find that small changes in parameter values can tip the optimal response between very different solutions, but the extensions considered here create new types of solutions. In some instances, it can be optimal to incur perpetual epidemic waves even if the uncontrolled infection prevalence would settle down to a stable intermediate level.

The hammer and the jab: Are COVID-19 lockdowns and vaccinations complements or substitutes?

The COVID-19 pandemic has devastated lives and economies around the world. Initially a primary response was locking down parts of the economy to reduce social interactions and, hence, the virus' spread. After vaccines have been developed and produced in sufficient quantity, they can largely replace broad lock downs. This paper explores how lockdown policies should be varied during the year or so gap between when a vaccine is approved and when all who wish have been vaccinated. Are vaccines and lockdowns substitutes during that crucial time, in the sense that lockdowns should be reduced as vaccination rates rise? Or might they be complementary with the prospect of imminent vaccination increasing the value of stricter lockdowns, since hospitalization and death averted then may be permanently prevented, not just delayed? We investigate this question with a simple dynamic optimization model that captures both epidemiological and economic considerations. In this model, increasing the rate of vaccine deployment may increase or reduce the optimal total lockdown intensity and duration, depending on the values of other model parameters. That vaccines and lockdowns can act as either substitutes or complements even in a relatively simple model casts doubt on whether in more complicated models or the real world one should expect them to always be just one or the other. Within our model, for parameter values reflecting conditions in developed countries, the typical finding is to ease lockdown intensity gradually after substantial shares of the population have been vaccinated, but other strategies can be optimal for other parameter values. Reserving vaccines for those who have not yet been infected barely outperforms simpler strategies that ignore prior infection status. For certain parameter combinations, there are instances in which two quite different policies can perform equally well, and sometimes very small increases in vaccine capacity can tip the optimal solution to one that involves much longer and more intense lockdowns.

First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-24 on Potato (Solanum tuberosum) in Wisconsin.

Potato (Solanum tuberosum) crops are grown on over 25,090 ha in Wisconsin annually. Late blight, caused by Phytophthora infestans (Mont.) deBary, is a potentially devastating disease that affects tomato and potato crops in Wisconsin every few years when inoculum is introduced and weather conditions favor disease. Incidence and severity of late blight are highly variable in these few years due to differences in pathogen clonal lineages, their timing and means of introduction, and weather conditions. Prevention of this disease through prophylactic fungicide application can cost producers millions of dollars annually in additional chemical, fuel, and labor expenses. Populations of P. infestans in the U.S. have recently undergone significant genetic change, resulting in isolates with unique clonal lineages and epidemiological characteristics (1). In 2010, late blight epidemics were of low severity in discrete portions of a few fields and were seen exclusively on potato in two counties of central Wisconsin. Symptoms included water-soaked to dark brown circular lesions with pale green haloes accompanied by white fuzzy pathogen sporulation typically on leaf undersides in high humidity conditions. Infected plants were collected by professional crop consultants and submitted to the authors at the University of Wisconsin Vegetable Pathology Laboratory in Madison, Wisconsin. Eight isolates of P. infestans were generated from individual leaf samples, representing separate fields, by removing sporangia from sporulating lesions and placing onto Rye A agar amended with rifampicin and ampicillin. Axenic, single zoospore-derived cultures of isolates were generated from parent cultures and maintained on Rye A agar for further characterization. Mycelium was coenocytic with hyphal diameter of 5 to 8 µm (n = 50). Sporangia were limoniform to ovoid, semi- to fully papillate, caducous, had short pedicels, and were 36.22 × 19.11 µm (height × width; n = 50). The average length-width ratio was 1.91. Allozyme banding patterns at the glucose-6-phosphate isomerase (Gpi) locus indicated a 100/100/111 profile, consistent with the US-24 clonal lineage (3,4). Mating type assays confirmed the isolates to be A1 and intermediate insensitivity to mefenoxam was observed in vitro (4). Genomic DNA was extracted with a phenol:chloroform:isoamyl alcohol solution and restriction fragment length polymorphism (RFLP) analysis was performed using the RG-57 probe on a representative isolate and resulted in banding patterns consistent with US-24 (2,3). Clonal lineages of P. infestans documented in Wisconsin in previous epidemics included US-8 in the mid-1990s and US-1 in the 1970s. The US-24 (A1) clonal lineage was very widespread in the U.S. in 2010 and its presence in Wisconsin in the same year as identification of US-22 (A2) posed great concern for potential sexual recombination, oospore production, and soil persistence. Fortunately, the opposite mating types were separated spatiotemporally. To the best of our knowledge, this is the first report of the P. infestans clonal lineage US-24 causing late blight on potato in Wisconsin. References: (1) K. Deahl. (Abstr.) Phytopathology 100:S161, 2010. (2) S. B. Goodwin et al. Curr. Genet. 22:107, 1992. (3) Hu et al. Plant Dis. 96:1323, 2012. (4) A. C. Seidl and A. J. Gevens. (Abstr.) Phytopathology 101:S162, 2011.

First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-22 on Tomato and Potato in Wisconsin.

Tomato (Solanum lycopersicum) and potato (S. tuberosum) crops are grown on over 67,000 acres (27,114 hectares) in the state of Wisconsin each year. Late blight, caused by Phytophthora infestans (Mont.) deBary, is a potentially devastating oomycete pathogen that sporadically affects tomato and potato crops in the state. Prevention of this disease through prophylactic application of oomycete-specific fungicides can cost producers millions of dollars per year in additional chemical, fuel, and labor expenses. In 2009, late blight was observed on tomato and potato in over 25 Wisconsin counties. The epidemic initiated on tomato in southern WI in early August and progressed northward in the state with additional reports on tomato primarily from home gardens and small farms. Potato late blight was also identified but with limited incidence in central WI, likely due to routine fungicide programs in commercial production. Clonal lineages of P. infestans documented in Wisconsin in previous epidemics included US-1 in the 1970s and US-8 in the mid-1990s. Populations of P. infestans in the U.S. have recently undergone significant genetic changes, resulting in isolates with unique clonal lineages and epidemiological characteristics (1). Symptoms of late blight observed on tomato and potato included water-soaked to dark brown circular lesions with pale green haloes accompanied by signs of pathogen sporulation typically on leaf undersides during periods of high humidity. Isolates of P. infestans were generated from field infected tomato and potato foliar tissues. Axenic, single zoospore derived cultures were generated and maintained on Rye A agar for further characterization. Mycelium was coenocytic with hyphal diameter of 5 to 8 µm (n = 50). Sporangia were limoniform or ovoid, semi- to fully papillate, caducous, had short pedicels, and were 29.6 (h) × 16.8 µm (w) (n = 50). The average length/width ratio was 1.76. Allozyme banding patterns at the glucose-6-phosphate isomerase (Gpi) locus indicated a 100/122 profile, consistent with the US-22 clonal lineage (3). Mating type assays confirmed the isolates to be A2 and in vitro mefenoxam sensitivity was observed (4). Restriction fragment length polymorphic analysis of a representative isolate from Wisconsin with the multilocus RG57 sequence and EcoRI produced the DNA pattern indicative of US-22 (2). The P. infestans clonal lineage US-22 was predominant in U.S. epidemics on tomato in 2009. To our knowledge, this is the first report of P. infestans clonal lineage US-22 causing late blight on tomato and potato in Wisconsin, USA. References: (1) K. Deahl. (Abstr.) Phytopathology 100(suppl.):S161, 2010. (2) S. B. Goodwin et al. Curr. Genet. 22:107, 1992. (3) C. H. Hu et al. Plant Dis. 96:1323, 2012. (4) A. C. Seidl et al. Phytopathology 101(suppl.):S246, 2011.

First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-23 on Tomato and Potato in Wisconsin, United States.

Tomato (Solanum lycopersicum) and potato (S. tuberosum) crops are grown on over 67,000 acres (27,114 ha) in Wisconsin annually. Late blight, caused by Phytophthora infestans (Mont.) deBary, is a potentially devastating disease that affects tomato and potato crops in Wisconsin every few years when inoculum is introduced and weather conditions favor disease. Incidence and severity of late blight are highly variable in these few years due to differences in pathogen clonal lineages, their timing and means of introduction, and weather conditions. Prevention of this disease through preventative application of fungicides can cost producers millions of dollars per year in additional chemical, fuel, and labor expenses. In 2009, late blight caused by P. infestans clonal lineage US-23 was observed on potato very late in the season in Vernon County, southwestern Wisconsin, in very low incidence and severity. In 2010, US-23 again appeared but on tomato in two southeastern Wisconsin counties, Waukesha and Ozaukee, again in low incidence and severity. Clonal lineages of P. infestans documented in Wisconsin in previous epidemics included US-8 in the mid-1990s and US-1 in the 1970s. Populations of P. infestans in the United States have recently undergone significant genetic change, resulting in isolates with unique clonal lineages and epidemiological characteristics (1). Foliar symptoms included water-soaked to dark brown circular lesions with pale green haloes accompanied by white pathogen sporulation. On tomato fruit, lesions were firm, sunken, and brown. Isolates of P. infestans were generated from field-infected tomato and potato foliar and fruit tissues collected by the authors and professional crop consultants. In initial pathogen confirmation analysis in 2009, three isolates of P. infestans were generated from one potato plant exhibiting multiple lesions from one of eight fields tested by placing infected leaf excisions onto Rye A agar amended with rifampicin and ampicillin. Axenic, single zoospore-derived cultures of isolates were generated from parent cultures and maintained on Rye A agar for further characterization. In 2010, three US-23 isolates were recovered from three locations (two counties), out of 20 fields tested. Mycelium was coenocytic with hyphal diameter of 5 to 8 µm (n = 50). Sporangia were limoniform or ovoid, semi to fully papillate, caducous, had short pedicels, and were 26.16 µm high × 18.17 µm wide (n = 50). The average length/width ratio was 1.42. Allozyme banding patterns at the glucose-6-phosphate isomerase (Gpi) locus indicated a 100/100 profile, consistent with the US-23 clonal lineage (3) Mating type assays confirmed the isolates to be A1 and in vitro intermediate mefenoxam sensitivity was observed (4). Genomic DNA was extracted with a phenol/chloroform/isoamyl alcohol solution and RFLP analysis was performed using the RG-57 probe on a representative isolate and resulted in banding patterns consistent with US-23 (2,3). The P. infestans clonal lineage US-23 was present in epidemics in 2009 and 2010 in the United States. Disease symptoms associated with US-23 were observed exclusively on potato in 2009 and on tomato in 2010 in Wisconsin. To our knowledge, this is the first report of P. infestans clonal lineage US-23 causing late blight on tomato and potato in Wisconsin and represents a change in the composition of the pathogen population from previous epidemic years. References: (1) K. Deahl. (Abstr.) Phytopathology 100:S161, 2010. (2) S. B. Goodwin et al. Curr. Genet. 22:107, 1992. (3) Hu et al. Plant Dis. 96:1323, 2012. (4) A. C. Seidl and A. J. Gevens. (Abstr.) Phytopathology 101(suppl.):S162, 2011.

[IQWiG's methods for the cost-benefit assessment : Comparison with an international reference scenario]. / Wo steht die Kosten-Nutzen-Bewertung des IQWiG : Abgleich mit einem internationalen Referenzszenario?

Standardization of international health economic guidelines has been repeatedly requested. In this context, an international reference case was proposed, which constitutes an agreed approach for the key elements of health economic evaluation including study perspective, comparators, source of effectiveness data, role of modeling, main (economic) outcome, source of utilities, characterizing uncertainty. It is, however, questionable whether such a reference scenario can reasonably be applied across all health care systems. Our analysis pursues the question to which degree the Institute for Quality and Efficiency in Health Care's (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen, IQWiG) "General methods for evaluating the relation between cost and benefit" comply with the key elements of the reference case. In case of divergences, they will be described and discussed in light of the German social legislation and in consideration of current scientific evidence. In conclusion, the analysis revealed that IQWiG complied with the reference case in almost all aspects. Differences were found only with respect to the choice of main (economic) outcome and the source of utilities. These differences seem justified and well explained in the context of the German social legislation as well as in view of the weaknesses of the quality-adjusted life year (QALY) concept.

GAS TRANSPORT IN THE HAEMOLYMPH OF ARACHNIDS - OXYGEN TRANSPORT AND THE PHYSIOLOGICAL ROLE OF HAEMOCYANIN

Oxygen equilibrium curves and the relationships between the partial pressure of CO2 and pH were determined for the haemolymph of the arachnids Eurypelma californicum, Pandinus imperator and Cupiennius salei. A new type of experimental apparatus was constructed, tested and used to make these measurements on small undiluted cell-free haemolymph samples. Most of its components were made in our workshop and were inexpensive. The apparatus proved to be very reliable as demonstrated by control (oxygen concentration) experiments. In previous reports on O2 equilibrium curves of E. californicum haemocyanin, Tris­HCl buffer was used to set the pH, whereas in our experiments, pH was adjusted by altering the partial pressure of CO2. The O2 concentration measurements demonstrate an increase in oxygen affinity of E. californicum haemocyanin when using Tris­HCl buffer. The position and shape of the O2 equilibrium curves of E. californicum and P. imperator haemocyanin show a distinct dependency on pH. Oxygen affinity is lower in E. californicum and cooperativity changes with pH in E. californicum, but not in P. imperator. Oxygen transport in the haemolymph of E. californicum during rest, activity and recovery was calculated on the basis of the O2 equilibrium curves of undiluted haemolymph. Apart from oxygen transport, there are indications that haemocyanin is also involved in other physiological processes. For example, it may function as a storage protein.

GAS TRANSPORT IN THE HAEMOLYMPH OF ARACHNIDS - CARBON DIOXIDE TRANSPORT AND ACID-BASE BALANCE

The relationships between PCO2 and pH were determined in cell-free undiluted haemolymph of the arachnids Eurypelma californicum, Pandinus imperator and Cupiennius salei. The pH/bicarbonate diagrams and the CO2 equilibrium curves were calculated, using the Henderson­Hasselbalch equation, for haemolymph sampled at rest and during recovery from exercise. The calculations of solubility (alphaCO2) and dissociation constant (pK"') were based on additional ion concentration measurements. Blood gas analyses corroborate these results: after locomotor activity, there is a metabolic acidosis linked to the accumulation of lactate in the haemolymph. The concentration of bicarbonate in the haemolymph of resting individuals is quite different in the three species and is related to the extent of post-exercise bicarbonate depletion. During early recovery, buffering in the haemolymph strongly depends upon CO2 release. Potassium and magnesium concentrations in the haemolymph increase after exercise. During cold-acclimation (to 10 °C), there is a metabolic acidosis in the tarantula's haemolymph that is linked to the accumulation of acetate.

A financial analysis of treatment strategies for Trypanosoma evansi in the Brazilian Pantanal.

The Brazilian Pantanal is a 138,000 km2 tropical seasonal wetland located in the center of South America bordering Bolivia and Paraguay. The Pantanal contains approximately 1100 cattle ranches, 3 million cattle, 49,000 horses and a unique diversity of wildlife. Cattle ranching is the most important economic activity in the Pantanal. This study explores the direct financial impacts of the adoption of seven treatment strategies for the control of Trypanosoma evansi in the Brazilian Pantanal. T. evansi adversely affects the health of the horse population in the region. Horses are indispensable to the cattle ranching industry in the Pantanal. Estimated costs include risk of infection, costs of diagnosis, alternative treatments, collecting animals for treatment, and costs of animal losses. The estimated total cost of T. evansi to the Pantanal region's cattle ranchers is about US$2.4 million and 6462 horses/yr. Results indicate that one preventive and two curative treatment strategies are financially justifiable. The best available technology for the treatment of T. evansi from an economic perspective is a curative treatment employed year-round. This treatment represents an annual net benefit of more than US$2 million or US$1845/ranch and spares about 5783 horses. It represents an annual net benefit of over US$200,000 and 600 horses relative to the currently most widely adopted strategy.

[Experiences with a computer documentation of obstetrical data (author's transl)]. / Erfahrungen mit der EDV-Dokumentation geburtshilflicher Daten.

Experiences with a computer information system at the 2nd Department of Obstetrics and Gynaecology, University of Vienna Medical School are reported. The data input is done via video-terminals located at different places in the department. Included are anamnestic data, results of physical examinations, pelvic examinations and laboratory findings and data concerning the course of delivery. The print-out of the stored data replaces the conventional charts. The advantages of this information system are: 1. The support of the clinical routine work by a more accurate and systematic documentation; 2. a comprehensive compiling of the patients data; 3. all stored data are readily available for scientific evaluation.

[Documentation of obstetric case reports by means of video-terminals as a part of the Vienna General medical information system "WAMIS" (author's transl)]. / Die Dokumentation geburtshilflicher Krankengeschichten mit Hilfe von Bildschirmterminals im Rahmen des Informationssystems WAMIS

A report is given on the introduction of a complete documentation system of obstetric case reports by means of video-terminals and printer-terminals in both departments of Obstetrics and Gynaecology of the 1niversity of Vienna. The special routine for the admission of patients, which produces the heading of the case report is demonstrated, as well as the sheets of collecting the data in respect to case history, antenatal examinations, labour room reports and details of obstetric operations. The computer prints the case history using the collected data. These computer-printed case reports replace the customary handwritten reports. Laboratory data, therapeutic measures and final diagnosis are computed in the same way. The advantages of this form of organization of data collection for clinical purposes and research work are discussed.

[Prostaglandins compared with oxytocin for induction of labour at term (author's transl)]. / Vergleich von Prostaglandin und Oxytocin zur Geburtseinpleitung am Termin

12 cases of induction of labour with prostaglandin F2 alpha and 8 with prostaglandin E2 were compared with 14 cases in which induction was undertaken with oxytocin. All inductions were successful, the induction--delivery intervals being slightly shorter in the prostaglandin groups than in the oxytocin group. Both with prostaglandin F2 alpha and with prostaglandin E2 the cardiotocogram showed uterine hyperactivity in most of the cases with an unexpected, episodically-occurring increase in basal uterine tone and remarkable tachysystoly. Uterine hyper-activity led to fetal heart rate alterations of the "dip 2" type in about 50% of the cases. According to these results prostaglandins cannot be considered superior to oxytocin for the induction of labour at term.

Parent gender, victim gender, and family socioeconomic level influences on the potential reporting by nurses of physical child abuse.

In 1974, the Federal Child Abuse Prevention and Treatment Act required reporting of child abuse in all states. Although nurses have since this time been designated as mandated reporters of abuse, only recently have nurses begun to hold positions where they are directly responsible for abuse reporting. This study investigated whether the gender of the victim, the gender of the abusing parent, or the family's socioeconomic level influences the potential reporting of child abuse by nurses. Participants were shown three vignettes of children being admitted to an emergency room with symptoms of possible abuse. When asked if they would or would not report the incident as child abuse, participants indicated they were significantly less apt to report abuse when the victim was female rather than male, and when the family was perceived as being from a middle rather than a low or high socioeconomic background. The implication of this finding is that female children from middle-class backgrounds may be left less protected than others as nurses become more actively involved in child abuse reporting.

The new non-traditional student in nursing.

Because different types of new, non-registered nurse students seek baccalaureate nursing education, this study was conducted comparing traditional undergraduate generic students with a group of non-traditional students to dispel myths and to develop policies and educational strategies. Traditional and non-traditional students were differentiated by age, sex, marital status, and experience in higher education. Traditional and non-traditional undergraduate students were compared on demographic variables, educational goals, sources of psychological and financial support, study habits, learning style, and clinical judgment skills. Non-traditional students were found to be an excellent risk for admission, having higher semester grade point averages and being more skilled in making professional judgments. Learning style differentiated traditional and non-traditional students, however, teaching methods were similar. Suggestions for educational planning and policies are made. Let the curriculum of the institution recognize that both educational content and process must be relevant to individual differences and that the curriculum is basically what different individuals do to learn what they need to learn, to fulfill the purposes that brought them to the college (Chickering, 1974).

School administrators, parents, and sex education: a resolvable paradox?

The emergence of AIDS as an untreatable, lethal disease, responding to educational prevention strategies in high-risk populations, has brought the issues of sex education in the public schools to the forefront. However, administrators, teachers, and parents perceive different barriers to sex education implementation. This study, undertaken in a northeastern, multigenerational, ethnic city, characterized by adolescent pregnancy rates a third higher than the state overall, polled 42 junior and senior high school administrators regarding educational priorities, perceived barriers to expansion of sex education, and preferred methods of introducing sex education. Administrators perceive parents as a major barrier to the introduction of more formalized sex education in their schools. Paradoxically, these same administrators felt that parents were generally uncomfortable in talking to their children about human sexuality. Recommendations are offered from existing models of health education for resolution of administrators' conflicting views on parental roles.

PIP: The emergence of Acquired Immunodeficiency Disease (AIDS) as an untreatable, lethal disease, responding to educational prevention strategies in high-risk populations, has brought the issue of sex education in the public schools to the forefront. Administrators, teachers and parents perceive different barriers to sex education implementation. This study, undertaken in a northeastern, multigenerational ethnic city, characterized by adolescent pregnancy rates 1/3 higher than the state overall, polled 42 junior and senior high school administrators regarding educational priorities, perceived barriers to expansion of sex education, and preferred methods of introducing sex education. Administrators perceive parents as a major barrier to the introduction of more formalized sex education in their schools. Paradoxically, these same administrators felt that parents were generally uncomfortable in talking to their children about human sexuality. Resolution of this apparent paradox between administrative perceptions and parental behavior may be achieved in a number of ways. One approach would be to pay more attention to what parents say they would do versus what they actually teach their children about sex. Findings from other communities' attempts to institute sex education in the public schools attest to parents' concerns, but also to the possibilities of working with parents to develop an acceptable sex education curriculum. For those administrators who plan to launch or expand a sex education curriculum, a body of data now exists to help anticipate and work through adult (parent and teacher) reactions.

Nurses' attitudes toward emotional, sexual, and physical abusers of children with disabilities.

Some studies have linked birth defects, disability, and chronic illness with an increased incidence of child abuse. Nurses who are involved with disabled children face a challenge in preventing child abuse and intervening in cases in which abuse has occurred. Nurse must become aware of the risk factors and signs of abuse, understand the role of their personal attitudes toward abuse and abusers, and develop the skills to intervene effectively and deal with abusers. Thus, the authors of this article undertook a study to ascertain nurses' attitudes about emotional, sexual, and physical abuse of children with disabilities and to determine if nurses' anticipated level of comfort differed when dealing with abusers of children with disabilities in contrast to abusers of children without disabilities.

Understanding the effects of a myocardial infarction on sexual functioning: a basis for sexual counseling.

Sexual counseling is an integral component of the rehabilitative process for clients who have experienced a myocardial infarction (MI). This article describes myths and fears concerning the dangers of resuming sexual intercourse after a heart attack, positions for intercourse, and the effects of intercourse on arrhythmias, angina, and blood pressure. The purpose is to provide the results of empirical research to dispel myths and fears and to consider the causes of sexual dysfunction, the changes MI brings about in sexual activity for men and women, and the effects of age, exercise, and antihypertensive drugs on the resumption of sexual activity. Guidelines are provided for conducting a sexual/cardiac history as part of the counseling model with specific information for the post-MI client.

Regulation of conduction time along axons.

Timely delivery of information is essential for proper functioning of the nervous system. Precise regulation of nerve conduction velocity is needed for correct exertion of motor skills, sensory integration and cognitive functions. In vertebrates, the rapid transmission of signals along nerve fibers is made possible by the myelination of axons and the resulting saltatory conduction in between nodes of Ranvier. Myelin is a specialization of glia cells and is provided by oligodendrocytes in the central nervous system. Myelination not only maximizes conduction velocity, but also provides a means to systematically regulate conduction times in the nervous system. Systematic regulation of conduction velocity along axons, and thus systematic regulation of conduction time in between neural areas, is a common occurrence in the nervous system. To date, little is understood about the mechanism that underlies systematic conduction velocity regulation and conduction time synchrony. Node assembly, internode distance (node spacing) and axon diameter - all parameters determining the speed of signal propagation along axons - are controlled by myelinating glia. Therefore, an interaction between glial cells and neurons has been suggested. This review summarizes examples of neural systems in which conduction velocity is regulated by anatomical variations along axons. While functional implications in these systems are not always clear, recent studies on the auditory system of birds and mammals present examples of conduction velocity regulation in systems with high temporal precision and a defined biological function. Together these findings suggest an active process that shapes the interaction between axons and myelinating glia to control conduction velocity along axons. Future studies involving these systems may provide further insight into how specific conduction times in the brain are established and maintained in development. Throughout the text, conduction velocity is used for the speed of signal propagation, i.e. the speed at which an action potential travels. Conduction time refers to the time it takes for a specific signal to travel from its origin to its target, i.e. neuronal cell body to axonal terminal.