The effect of respiratory activity, non-invasive respiratory support and facemasks on aerosol generation and its relevance to COVID-19.

Respirable aerosols (< 5 µm in diameter) present a high risk of SARS-CoV-2 transmission. Guidelines recommend using aerosol precautions during aerosol-generating procedures, and droplet (> 5 µm) precautions at other times. However, emerging evidence indicates respiratory activities may be a more important source of aerosols than clinical procedures such as tracheal intubation. We aimed to measure the size, total number and volume of all human aerosols exhaled during respiratory activities and therapies. We used a novel chamber with an optical particle counter sampling at 100 l.min-1 to count and size-fractionate close to all exhaled particles (0.5-25 µm). We compared emissions from ten healthy subjects during six respiratory activities (quiet breathing; talking; shouting; forced expiratory manoeuvres; exercise; and coughing) with three respiratory therapies (high-flow nasal oxygen and single or dual circuit non-invasive positive pressure ventilation). Activities were repeated while wearing facemasks. When compared with quiet breathing, exertional respiratory activities increased particle counts 34.6-fold during talking and 370.8-fold during coughing (p < 0.001). High-flow nasal oxygen 60 at l.min-1 increased particle counts 2.3-fold (p = 0.031) during quiet breathing. Single and dual circuit non-invasive respiratory therapy at 25/10 cm.H2 O with quiet breathing increased counts by 2.6-fold and 7.8-fold, respectively (both p < 0.001). During exertional activities, respiratory therapies and facemasks reduced emissions compared with activities alone. Respiratory activities (including exertional breathing and coughing) which mimic respiratory patterns during illness generate substantially more aerosols than non-invasive respiratory therapies, which conversely can reduce total emissions. We argue the risk of aerosol exposure is underappreciated and warrants widespread, targeted interventions.

Towards remote healthcare monitoring using accessible IoT technology: state-of-the-art, insights and experimental design.

Healthcare studies are moving toward individualised measurement. There is need to move beyond supervised assessments in the laboratory/clinic. Longitudinal free-living assessment can provide a wealth of information on patient pathology and habitual behaviour, but cost and complexity of equipment have typically been a barrier. Lack of supervised conditions within free-living assessment means there is need to augment these studies with environmental analysis to provide context to individual measurements. This paper reviews low-cost and accessible Internet of Things (IoT) technologies with the aim of informing biomedical engineers of possibilities, workflows and limitations they present. In doing so, we evidence their use within healthcare research through literature and experimentation. As hardware becomes more affordable and feature rich, the cost of data magnifies. This can be limiting for biomedical engineers exploring low-cost solutions as data costs can make IoT approaches unscalable. IoT technologies can be exploited by biomedical engineers, but more research is needed before these technologies can become commonplace for clinicians and healthcare practitioners. It is hoped that the insights provided by this paper will better equip biomedical engineers to lead and monitor multi-disciplinary research investigations.

Airborne transmission of severe acute respiratory syndrome coronavirus-2 to healthcare workers: a narrative review.

Healthcare workers are at risk of infection during the severe acute respiratory syndrome coronavirus-2 pandemic. International guidance suggests direct droplet transmission is likely and airborne transmission occurs only with aerosol-generating procedures. Recommendations determining infection control measures to ensure healthcare worker safety follow these presumptions. Three mechanisms have been described for the production of smaller sized respiratory particles ('aerosols') that, if inhaled, can deposit in the distal airways. These include: laryngeal activity such as talking and coughing; high velocity gas flow; and cyclical opening and closure of terminal airways. Sneezing and coughing are effective aerosol generators, but all forms of expiration produce particles across a range of sizes. The 5-µm diameter threshold used to differentiate droplet from airborne is an over-simplification of multiple complex, poorly understood biological and physical variables. The evidence defining aerosol-generating procedures comes largely from low-quality case and cohort studies where the exact mode of transmission is unknown as aerosol production was never quantified. We propose that transmission is associated with time in proximity to severe acute respiratory syndrome coronavirus-1 patients with respiratory symptoms, rather than the procedures per se. There is no proven relation between any aerosol-generating procedure with airborne viral content with the exception of bronchoscopy and suctioning. The mechanism for severe acute respiratory syndrome coronavirus-2 transmission is unknown but the evidence suggestive of airborne spread is growing. We speculate that infected patients who cough, have high work of breathing, increased closing capacity and altered respiratory tract lining fluid will be significant producers of pathogenic aerosols. We suggest several aerosol-generating procedures may in fact result in less pathogen aerosolisation than a dyspnoeic and coughing patient. Healthcare workers should appraise the current evidence regarding transmission and apply this to the local infection prevalence. Measures to mitigate airborne transmission should be employed at times of risk. However, the mechanisms and risk factors for transmission are largely unconfirmed. Whilst awaiting robust evidence, a precautionary approach should be considered to assure healthcare worker safety.

Pathogen and Particle Associations in Wastewater: Significance and Implications for Treatment and Disinfection Processes.

Disinfection guidelines exist for pathogen inactivation in potable water and recycled water, but wastewater with high numbers of particles can be more difficult to disinfect, making compliance with the guidelines problematic. Disinfection guidelines specify that drinking water with turbidity ≥1 Nephelometric Turbidity Units (NTU) is not suitable for disinfection and therefore not fit for purpose. Treated wastewater typically has higher concentrations of particles (1-10NTU for secondary treated effluent). Two processes widely used for disinfecting wastewater are chlorination and ultraviolet radiation. In both cases, particles in wastewater can interfere with disinfection and can significantly increase treatment costs by increasing operational expenditure (chemical demand, power consumption) or infrastructure costs by requiring additional treatment processes to achieve the required levels of pathogen inactivation. Many microorganisms (viruses, bacteria, protozoans) associate with particles, which can allow them to survive disinfection processes and cause a health hazard. Improved understanding of this association will enable development of cost-effective treatment, which will become increasingly important as indirect and direct potable reuse of wastewater becomes more widespread in both developed and developing countries. This review provides an overview of wastewater and associated treatment processes, the pathogens in wastewater, the nature of particles in wastewater and how they interact with pathogens, and how particles can impact disinfection processes.

Sexual rest and post-meiotic sperm ageing in house mice.

Fertilization by aged sperm can result in adverse fitness consequences for both males and females. Sperm storage during male sexual rest could provide an environment for post-meiotic sperm senescence causing a deterioration in the quality of stored sperm, possibly impacting on both sperm performance (e.g. swimming ability) and DNA quality. Here, we compared the proportion of sperm with fragmented DNA, an indicator of structural damage of DNA within the sperm cell, among males that had been sexually rested for approximately 2 months, to that of males that had mated recently. We found no evidence of intra-epididymal sperm DNA damage or any impairment in sperm performance, and consequently no evidence of post-meiotic sperm senescence. Our results suggest that male house mice are likely to possess mechanisms that function to ensure that their sperm reserves remain stocked with 'young', viable sperm during periods of sexual inactivity. We also discuss the possibility that our experimental design leads to no difference in the age of sperm among males from the two mating treatments. Post-meiotic sperm senescence is especially relevant under sperm competition. Thus, we sourced mice from populations that differed in their levels of post-copulatory sexual selection, enabling us to gain insight into how selection for higher sperm production influences the rate of sperm ageing and levels of DNA fragmentation. We found that males from the population that produced the highest number of sperm also had the smallest proportion of DNA-fragmented sperm and discuss this outcome in relation to selection acting upon males to ensure that they produce ejaculates with high-quality sperm that are successful in achieving fertilizations under competitive conditions.

Life coaching following haematopoietic stem cell transplantation: a mixed-method investigation of feasibility and acceptability.

Haematopoietic stem cell transplantation (HSCT) cures many haematological cancers. Recovery post-HSCT is physically and psychologically challenging, lasting several months. Beyond the first post-transplant year, a fifth report difficulties encompassing practical, social and emotional domains, including finance and employment. We investigated the feasibility, acceptability and impact of a life coaching intervention designed to address psychosocial 'survivor' concerns of HSCT recipients and facilitate transition to life post-treatment. A concurrent embedded experimental mixed-method design was employed. Pre- and post-intervention data collection comprised qualitative semi-structured telephone interviews and quantitative postal questionnaires. Seven purposively sampled HSCT recipients (<18 months) participated, reporting on one-to-one life coaching delivered by a professional life coach fortnightly over 8 weeks. Participants reported less anxiety, depression and fewer survivor concerns post-intervention, with a trend for lower social difficulties and increased functional well-being. Perceived self-efficacy was unchanged. Life coaching was feasible to deliver and acceptable to the participants who indicated it was a positive experience, with benefits described in diverse areas including work, lifestyle and hobbies. Life coaching within cancer services potentially offers the means to address psychosocial concerns and support transition to life after treatment, enabling patients to reach their potential, e.g. returning to employment and financial independence. Further investigation of this intervention in cancer survivors is warranted.

Torsades de pointes - a report of a case induced by caesium taken as a complementary medicine, and the literature review.

WHAT IS KNOWN AND OBJECTIVE: Complementary medicines are commonly used by many patients. Caesium, a complementary therapy said to be of benefit for cancer treatment, has been associated with cardiac arrhythmias in the literature. We report a case of caesium-induced torsades de pointes and provide an evidence review. CASE SUMMARY: A 46-year-old woman with syncope experienced torsades de pointes and cardiac arrest. Upon admission her QTc was 620 ms. The patient had taken caesium carbonate 10 g daily for 1 month prior to admission. The patient was successfully resuscitated and discharged home after 35 days in hospital. WHAT IS NEW AND CONCLUSION: Ten cases of caesium-induced cardiac arrhythmias have previously been reported in the literature. Treatment strategies differed significantly among the cases. However, all patients recovered from the event. Complementary and alternative medicines should not be overlooked as a potential cause of serious adverse events.

Relationship between ambient temperature at sampling and the interferon gamma test result for bovine tuberculosis in cattle.

Bovine tuberculosis (bTB) is a disease of significant economic and zoonotic importance, therefore, optimising tests for the identification of Mycobacterium bovis infected cattle is essential. The Interferon Gamma (IFN-γ) Release Assay (IGRA) can diagnose M. bovis infected cattle at an early stage, is easy to perform and can be used alongside skin tests for confirmatory purposes or to increase diagnostic sensitivity. It is known that IGRA performance is sensitive to environmental conditions under which samples are taken and transported. In this study, the association between the ambient temperature on the day of bleeding and the subsequent IGRA result for bTB was quantified using field samples from Northern Ireland (NI). Results of 106,434 IGRA results (2013-2018) were associated with temperature data extracted from weather stations near tested cattle herds. Model dependent variables were the levels of IFN-γ triggered by avian purified protein derivative (PPDa), M. bovis PPD (PPDb), their difference (PPD(b-a)) as well as the final binary outcome (positive or negative for M. bovis infection). IFN-γ levels after both PPDa and PPDb stimulation were lowest at the extremes of the temperature distribution for NI. The highest IGRA positive probability (above 6%) was found on days with moderate maximum temperatures (6-16 °C) or moderate minimum temperatures (4-7 °C). Adjustment for covariates did not lead to major changes in the model estimates. These data suggest that IGRA performance can be affected when samples are taken at high or low temperatures. Whilst it is difficult to exclude physiological factors, the data nonetheless supports the temperature control of samples from bleeding through to laboratory to help mitigate post-collection confounders.

Identification and management of ocular lipid deposition in association with hyperlipidaemia in captive moray eels, Gymnothorax funebris Ranzani, Gymnothorax moringa (Cuvier) and Muraena retifera Goode and Bean.

Ocular lipid deposition and its surgical management and possible association with systemic hyperlipidaemia in captive moray eels are described. Ophthalmologic examinations, haematology and plasma biochemistry analyses were performed on an initial population of captive moray eels (n=10): green moray, Gymnothorax funebris Ranzani; spotted moray, Gymnothorax morninga (Cuvier) and reticulated moray, Muraena retifera Goode and Bean. Recently captured green moray eels comprised the control group (n=9). Clinical signs compatible with ocular lipid deposition were identified in six of ten captive eels (60%) vs. none of the controls. Green moray eels in the initial captive population (n=5) had significantly higher total protein, triglyceride, cholesterol and aspartate amino transferase values than the control eels. Dietary management was attempted in all captive eels, and surgical intervention was performed in three eels, including two from a separate population, with improved ocular clarity within 1month post-operatively. Histopathological evaluation of surgical specimens and two eyes from an additional affected eel that died suggested ocular lipid deposition. Eels in captivity have an apparent predisposition for hyperlipidaemia and ocular lipid deposition. Although limited in this study and complicated by exhibit restraints, dietary management was minimally effective, while surgery improved ocular clarity.

An evaluation of the effect of altering nutrition and nutritional strategies in early lactation on reproductive performance and estrous behavior of high-yielding Holstein-Friesian dairy cows.

Reproductive performance in the high-yielding dairy cow has severely decreased in the last 40 yr. The aim of this study was to compare the effectiveness of 4 nutritional strategies in improving the reproductive performance of high-yielding dairy cows. It was hypothesized that offering cows a high-starch ration in early lactation would enhance the onset of luteal activity, and that decreasing the severity of negative energy balance in the early postcalving period would improve reproductive parameters. Nutritional regimens aimed at improving fertility were applied to 96 Holstein-Friesian dairy animals. Upon calving, animals were allocated in a balanced manner to one of 4 dietary treatments. Primiparous animals were balanced according to live weight, body condition score and calving date. Multiparous animals were balanced according to parity, previous lactation milk yield, liveweight, body condition score and calving date. Treatment 1 was based on an industry best practice diet (control) to contain 170 g of crude protein/kg of dry matter. Treatment 2 was an individual cow feeding strategy, whereby the energy balance (EB) of individual animals was managed so as to achieve a predetermined target daily EB profile (±10 MJ/d). Treatment 3 was a high-starch/high-fat combination treatment, whereby an insulinogenic (high-starch) diet was offered in early lactation to encourage cyclicity and followed by a lipogenic (low-starch, high-fat) diet to promote embryo development. Treatment 4 was a low-protein diet, containing 140 g of crude protein/kg of dry matter, supplemented with protected methionine at an inclusion level of 40 g per animal per day. The nutritional strategies implemented in this study had no statistically significant effects on cow fertility measures, which included the onset of luteal activity, conception rate, in-calf rate, and the incidence of atypical cycles. The individual cow feeding strategy improved EB in early lactation but had no benefit on conception rate to first insemination. However, conception rate to second insemination, 100-d pregnancy rate (from the commencement of breeding), and overall pregnancy rate tended to be higher in this group. The high-starch/high-fat treatment tended to decrease the proportion of delayed ovulations and increase the proportion of animals cycling by d 50 postcalving. Animals that failed to conceive to first insemination had a significantly longer luteal phase in the first cycle postpartum and a longer inter-ovulatory interval in the second cycle postpartum. With regards to estrous behavior, results indicate that as the size of the sexually active group increased, the intensity of estrus and the expression of mounting or attempting to mount another cow also increased. Furthermore, cows that became pregnant displayed more intense estrous behavior than cows that failed to become pregnant.

Effect of precalving and postcalving dietary energy level on performance and blood metabolite concentrations of dairy cows throughout lactation.

The effects of the level of energy intake (high E and low E) offered before and after calving on body condition score at calving, production performance, and energy status in the first 250 d of lactation were evaluated in a 2 × 2 factorial design experiment involving 80 Holstein-Friesian dairy animals (40 primiparous and 40 multiparous). From d 80 until d 21 precalving, primiparous animals were offered either high or low pasture allowances. Thereafter, these animals were housed and had ad libitum access to a high energy density diet (high E) or restricted access [6 kg of dry matter (DM) per d] to a low energy density diet (low E), respectively, until calving. From d 100 until d 42 precalving, multiparous animals were offered either ad libitum or restricted (10 kg of DM/d) access to a late lactation diet, and thereafter, had ad libitum access to a high E diet or restricted access (7 kg of DM complete diet/d) to a low E diet, respectively, until calving. The forage to concentrate (F:C) ratios (DM basis) of these high E and low E diets [d 42 (d 21 in primiparous animals) until calving] were 64:36 and 83:17, respectively. Cows offered high E and low E precalving diets were allocated to either a high E or low E postcalving diet [F:C ratio (DM basis) of 30:70 and 70:30, respectively] and remained on these diets until d 250 of lactation. Multiparous animals offered a high E diet precalving had a significantly higher body condition score at calving than those offered the low E diet precalving. This effect was not evident in primiparous animals. Precalving diet had no significant effect on plasma nonesterified fatty acid concentrations during the last 3 wk precalving in primi- or multiparous animals. Primiparous animals offered a high E diet precalving had significantly higher postcalving plasma concentrations of nonesterified fatty acid, suggesting greater mobilization of body reserves. Primi- and multiparous animals offered a high E diet postcalving had a significantly higher dry matter intake, milk yield, and energy status postcalving compared with animals offered a low E diet postcalving. Milk yields of primiparous animals offered high E and low E diets postcalving were 29.7 and 24.8 kg/d, respectively, and milk yield of multiparous animals offered high E and low E diets postcalving were 33.5 and 28.2 kg/d, respectively. It is concluded that altering body condition score during the dry period is difficult but that specific dietary regimens applied precalving can have a significant influence on postcalving production and energy-related parameters.

[Gallstone disease post-radical gastrectomy for gastric adenocarcinoma at the National Institute of Neoplastic Diseases, January 1990 to December 2000]. / Litiasis vesícular post- gastrectomía radical por adenocarcinoma gástrico en el Instituto Nacional de Enfermedades Neoplásicas, enero 1990 a diciembre del 2000.

SUBJECT: To determinate the frecuency and the time of development of the gallbladder stones in gastrectomy post-operated patients with stomach adenocarcinoma at The National Cancer Institute in Lima, Peru. METHODS: In an observational, descriptive and retrospective case series design, 148 patiens' files who underwent gastrectomy for stomach adenocarcinoma in the National Cancer Institue of Lima during 1990 and 2000, have been reviewed looking for the development of gallbladder stones. RESULTS: A total de 148 patients were involved in this study. 29 of them (19.6%) develop gallbladder stones during the (x years of) follow up vs 119 (80.9%) . The mean age ot the 29 patients with gallbladder stones were 59.9 years ans 18 of them were female and 11 male.\The mean time of develop gallbladder stones was 3.1 years.According to the type of surgery, 14 patient wiht gallbladder stones underwent to subtotal gastrectomy and 15 to total gastrectomy. CONCLUSIONS: The frecuency of gallbladder stones post gastrectomy in this study was 19.6%. The mean time of the develop and diagnosis of litiasis was 3.1 years.To perform the colecistectomy at the same time of the gastrectomy could be an important decision in patients with high risk of gallstones and gallbladder cancer.We need furthermore studies to have conclusions about the risk factors.

Autoantibodies encoded by the most Jh-proximal human immunoglobulin heavy chain variable region gene.

Little is known about the utilization of human Ig heavy chain variable gene segments (VH segments) in different B-lineage cell populations or in antibodies of particular specificity and function. We now demonstrate that human antibodies with Ig VH regions encoded by the most JH-proximal human VH segment (VH6) have specificities resembling those of autoantibodies present in sera of patients with systemic lupus erythematosus (e.g., anti-DNA and anticardiolipin). These specificities appear to be encoded by the germline VH6 gene because the activity was found in multiple independent VH6 antibodies in which the light chain varied with respect to isotype and V kappa subgroup. Features of CDR3 length and somatic mutation patterns in several VH6 antibodies suggested that they were selected by the immune system.

Quantification of viable granulosa cells in murine ovarian follicles.

Ovarian follicle growth and oocyte maturation depend on the viability of granulosa cells (GC). We quantified GC in whole mouse follicles. Single follicles were isolated from adult mouse ovaries and stained with DAPI or Live-Dead stain before fixation. An objective image analysis protocol for counting fluorescent labeled GC was developed that used Image J software to measure GC cytoplasmic and nuclear areas. These data were compared to the number of GC obtained by disaggregating 96 follicles with enzymes to produce a suspension of GC, which then was stained with trypan blue and assessed using a hemocytometer. We found a linear relation between GC/follicle and follicle diameter. Viability of GC/follicle ranged from 40 ± 11 to 72 ± 7%. The coefficient of variation for image analysis of DAPI stained GC by different assessors was 4%, but the number of GC obtained from image analysis was approximately 50% less than from disaggregated follicles. The number of GC in intact mouse follicles was greater than the number reported earlier for fixed ovarian sections. We found that the number of GC was less in fluorescence labeled follicles; it is possible that the three-dimensional structure of the intact follicles obscured the fluorescent signal. Direct quantification of viable GC isolated from follicles appears to be the most accurate method.

A time for restraint.

The debate on the use of human embryos for research will be one of the more important issues of the 21st century. Unlike recombinant DNA technology, embryonic stem cell research most probably will result in the destruction of living embryos. Many people consider this research immoral, illegal, and unnecessary. Therefore, it is imperative to proceed cautiously. Federal funding of research using human embryos or pluripotent cells derived from them would be inappropriate until further resolution of the ethical issues has been achieved.

Cholesterol dissolution rate in micellar bile acid solutions: retarding effect of added lecithin.

In vitro studies on the dissolution rate of cholesterol monohydrate crystals in micellar bile acid solutions showed that the addition of lecithin decreases the dissolution rate even though lecithin increases the equilibrium solubility of cholesterol in these solutions. The reduction in rates caused by lecithin was attributed to a large crystal-solution interfacial barrier. An effective permeability coefficient for the interfacial barrier was calculated to be around 1.5 x 10(-5) centimeter per second for the transport of cholesterol molecules.

Deoxyribonucleic acid antibody: a method to detect its primary interaction with deoxyribonucleic acid.

Antibody to DNA in human serums can be detected by the ammonium sulfate method. This sensitive and specific technique, which measures the primary interaction between DNA and antibody to DNA, is based on the observation that free DNA is soluble in 50-percent saturated ammonium sulfate whereas antibody-bound DNA is insoluble.

Effect of dietary protein content on the fertility of dairy cows during early and mid lactation.

Ninety autumn-calving Holstein dairy cows (45 primiparous and 45 multiparous; mean parity, 3.1) were allocated to 1 of 3 treatments; 173, 144, or 114 g of crude protein (CP)/kg of dry matter (DM) from calving until d 150 of lactation. On d 151 of lactation, half the animals receiving 114 g of CP/kg of DM went onto 144 g of CP/kg of DM, half of the animals receiving 144 g of CP/kg of DM went onto 173 g of CP/kg of DM, and half of the animals receiving 173 g of CP/kg of DM went onto 144 g of CP/kg of DM, with the remaining animals staying on their original treatments. This resulted in 6 treatments in mid to late lactation: 114/114; 144/144; 173/173; 114/144; 144/173; and 173/144 g of CP/kg of DM. Overall, 95.3% of cows intended for breeding conceived during a 6-mo breeding period. The average pregnancy rates to first service and first plus second service were 30.9% [standard error of the difference (SED), 0.05] and 56.7% (SED, 0.05) respectively. The average 100 d in-calf rate from the start of the breeding period was 70.5%, and at least one abnormal progesterone profile was observed in 62% of animals. An increase in dietary protein content decreased the requirement for treatment of metritis. There was no effect of dietary protein content on any of the reproductive or progesterone measures; for example, days to conception, calving interval, 100 d in-calf rate (from commencement of breeding), days to onset of luteal activity, average luteal phase, average interovulatory interval, or average interluteal interval. An increase in dietary protein content decreased the average daily energy balance. A more positive energy balance was associated with an increased requirement for the treatment of metritis in the current study. Cumulative energy balance was positively associated with conception. There was no effect of the concentration of plasma urea on any of the reproductive variables; however, the concentration of serum leptin was favorably associated with the time to progesterone increase above 3 ng/mL, which has been deemed essential for embryo survival. Additionally, the average peak concentration of progesterone and the duration of the average luteal phase were favorably associated with the interval from calving to conception. The latter relationships emphasize the importance of progesterone in achieving and maintaining pregnancy.

Effect of dietary protein content on animal production and blood metabolites of dairy cows during lactation.

Ninety autumn-calving Holstein dairy cows [45 primiparous and 45 multiparous (mean parity, 3.1)] were allocated to 1 of 3 dietary crude protein (CP) concentrations: 173, 144, or 114 g of CP/kg of DM, from calving until d 150 of lactation. On d 151, half of the animals in each treatment were allocated an alternative dietary protein concentration. Half of the animals receiving 114 g of CP/kg of DM went onto 144 g of CP/kg of DM; half of the animals receiving 144 g of CP/kg of DM went onto 173 g of CP/kg of DM; and half of the animals receiving 173 g of CP/kg of DM went onto 144 g of CP/kg of DM, with the remaining animals staying on their original treatment. This resulted in 6 treatments in the mid to late lactation period: 114/114, 144/144, 173/173, 114/144, 144/173, and 173/144 g of CP/kg of DM. An increase in dietary CP concentration significantly increased milk, fat, and protein yield in early lactation (d 1 to 150). Dry matter intake was also increased with increased dietary protein concentration; however, this was not significant between 144 and 173 g of CP/kg of DM. Increased dietary CP significantly increased plasma urea, albumin, and total protein concentrations but had no significant effect on NEFA, leptin, or IGF-1 concentrations. Decreasing the dietary CP concentration in mid-late lactation (d 151 to 305) from 173 to 144 g/kg of DM had no significant effect on milk yield, dry matter intake, or milk fat and protein yield, compared with animals that remained on 173 g of CP/kg of DM throughout lactation. Increasing dietary CP concentration from 144 to 173 g/kg of DM significantly increased dry matter intake compared with animals that remained on the 144 g of CP/kg of DM throughout lactation. There were no significant dietary treatment effects on live weight or body condition score change throughout the experiment. Results of this study indicate that high protein diets (up to 173 g of CP/kg of DM) improved feed intake and animal performance in early lactation (up to d 150), but thereafter, protein concentration can be reduced to 144 g of CP/kg of DM with no detrimental effects on animal performance.