Modeling daily yields of milk, fat, protein, and lactose of New Zealand dairy goats undergoing standard and extended lactations

This study aimed to assess the milk production data for New Zealand dairy goats in either a standard lactation (SL; ≤305 d in milk [DIM]) or extended lactation (EL; >305 and ≤670 DIM) using a random regression (RR) with third- and fifth-order Legendre polynomials, respectively. Persistency of EL was defined as (B/A) × 100, where A was the accumulated yield from d 1 to 305, and B was the accumulated yield from d 366 to 670. On average, goats in SL produced 1,183 kg of milk, 37 kg of fat, 37 kg of protein, and 54 kg of lactose. The average production of milk, fat, protein, and lactose in EL were 2,473 kg, 78 kg, 79 kg, and 112 kg, respectively. The average persistences for milk, fat, protein, and lactose yields during EL were 98%, 98%, 102%, and 96%, respectively. The relative prediction errors were close to 10% and the concordance correlation coefficients >0.92, indicating that the RR model with Legendre polynomials is adequate for modeling lactation curves for both SL and EL. Total yields and persistency were analyzed with a mixed model that included the fixed effects (year, month of kidding, parity, and proportion of Saanen) as covariates and the random effects of animal and residual errors. Effects of year, month of kidding, and parity were significant on the total yields of milk, fat, protein, and lactose for both SL and EL. The total milk yield of first-parity goats with SL was 946 kg and the total milk yield of second-parity goats with SL was 1,284 kg, making a total of 2,230 kg over 2 years. The total milk yield of a first-parity goat with EL was 2,140 kg. Thus, on average, a goat with SL for the first and second parity produced 90 kg more milk than a first-parity goat subjected to EL. However, a second-parity goat subjected to EL produced 43 kg more milk (2,639 kg) than a goat with SL following the second and third parity (1,284 kg + 1,312 kg). These data, along with the various other benefits of EL (e.g., fewer offspring born and reduced risk of mastitis, lameness, and metabolic problems in early lactation), indicate that EL as a management strategy holds the potential to improve dairy goat longevity and lifetime efficiency without compromising milk production.

Investigating the use of local nerve blocks and general anaesthesia in reducing pain during and after disbudding procedure in goat kids

The aim of this study was to compare the pain responses (as measured by noise and movement) during administration of local anaesthetic and during and after disbudding in goat kids. Eighty, seven- to ten-day-old, Saanen goat kids from one farm were enrolled and randomly assigned to one of four different methods of pain relief. Twenty kids had local anaesthetic (LA) applied at two sites per horn bud (LA group), 20 kids had LA applied to the two locations using a jet injector (JI group) and 20 kids were given a general anaesthetic (GA) using a combination of 0.02 mg/kg medetomidine and 2 mg/kg ketamine followed by a horn bud block applied as per the LA group (GA group). The remaining 20 kids had no treatment other than meloxicam (control group). Although responses between goat kids and at different time periods were variable, in comparison to the control group, GA eliminated the responses associated with injection of lignocaine and the responses during the period of disbudding, and provided a reduction in head scratches and shakes across multiple time periods.

Comparison of Three Anaesthetic Options to Reduce Acute Pain Response in Kid Goats

Three options for anesthetizing the skin around the horn bud of dairy goat kids were explored. Forty-five <10-day-old Saanen goat kids from were randomly split into five treatment groups (topical anesthetic cream (TA), vapocoolant spray (VS), local anesthetic applied by jet injector (JI), control - no treatment but painful stimulus applied (C), sham - no treatment and touching sites with a finger. The painful stimulus was multiple needle pricks on the skin around the horn bud. The outcome variables measured were heart rate movement, and vocalization during treatment application and administration of a painful stimulus around the horn bud. Heart rates were greater during application of a VS compared to TA.Neither the TA nor the VS appeared to have any effect on the response to the painful stimulus. Kids in the JI group had a 96% reduced odds of expressing a marked pain response in comparison to TA group and an 83% reduction in the odds of a high movement grade during a painful procedure in comparison to the combined results of the other three treatment groups.

Effect of dose rate and timing of administration of pegbovigrastim on white blood cell responses in grazing dairy cows

Transition dairy cows experience a decline in immune function that increases the risk of peripartum disease. One strategy to improve peripartum immune function involves the use of a commercially available cytokine: bovine granulocyte-colony stimulating factor, with the addition of polyethylene glycol to increase duration of effectiveness. Treatment with Imrestor (15 mg pegbovigrastim; Elanco) one week before expected calving date (d -7) and again on the day of calving (d 0) was previously reported to increase the neutrophil number and improve neutrophil function; as a result, the incidence of clinical mastitis was reduced. We conducted 2 experiments over consecutive years to investigate the effect of a lower dose rate (half or quarter dose rate) of Imrestor in grazing dairy cattle and reduced administration frequency: one dose instead of the recommended 2. White blood cell counts were measured to determine changes in relative cell populations in response to treatment. Neutrophil function was assessed by measuring myeloperoxidase activity. Imrestor treatment increased the numbers of neutrophils, band cells, lymphocytes, and monocytes until 14 d postcalving in a dose-dependent manner; it also increased neutrophil myeloperoxidase activity. One dose of Imrestor increased white blood cell counts and myeloperoxidase activity, but the timing, degree, and duration of the response were different relative to the recommended 2 doses and were also dependent upon when Imrestor treatment was given. One dose at d -7 relative to expected calving date did not have a lasting effect postcalving, whereas one dose only on d 0 caused a delayed effect relative to cows that received 2 doses. There was no effect of Imrestor on milk yield or on blood indicators of transition cow health. A lower dose rate of Imrestor or a single dose of Imrestor on the day of calving may be sufficient to improve neutrophil function during the early postpartum in grazing dairy cows. Large-scale field studies are required to determine whether the smaller response from lower dose rates or the timing of the immunological response to drug delivery affect animal health in early lactation.

Graduate Student Literature Review: Evaluating the appropriate use of wearable accelerometers in research to monitor lying behaviors of dairy cows

Until recently, animal behavior has been studied through close and extensive observation of individual animals and has relied on subjective assessments. Wearable technologies that allow the automation of dairy cow behavior recording currently dominate the precision dairy technology market. Wearable accelerometers provide new opportunities in animal ethology using quantitative measures of dairy cow behavior. Recent research developments indicate that quantitative measures of behavior may provide new objective on-farm measures to assist producers in predicting, diagnosing, and managing disease or injury on farms and allowing producers to monitor cow comfort and estrus behavior. These recent research developments and a large increase in the availability of wearable accelerometers have led to growing interest of both researchers and producers in this technology. This review aimed to summarize the studies that have validated lying behavior derived from accelerometers and to describe the factors that should be considered when using leg-attached accelerometers and neck-worn collars to describe lying behavior (e.g., lying time and lying bouts) in dairy cows for research purposes. Specifically, we describe accelerometer technology, including the instrument properties and methods for recording motion; the raw data output from accelerometers; and methods developed for the transformation of raw data into meaningful and interpretable information. We highlight differences in validation study outcomes for researchers to consider when developing their own experimental methodology for the use of accelerometers to record lying behaviors in dairy cows. Finally, we discuss several factors that may influence the data recorded by accelerometers and highlight gaps in the literature. We conclude that researchers using accelerometers to record lying behaviors in dairy cattle should (1) select an accelerometer device that, based on device attachment and sampling rate, is appropriate to record the behavior of interest; (2) account for cow-, farm-, and management-related factors that could affect the lying behaviors recorded; (3) determine the appropriate editing criteria for the accurate interpretation of their data; (4) support their chosen method of recording, editing, and interpreting the data by referencing an appropriately designed and accurate validation study published in the literature; and (5) report, in detail, their methodology to ensure others can decipher how the data were captured and understand potential limitations of their methodology. We recommend that standardized protocols be developed for collecting, analyzing, and reporting lying behavior data recorded using wearable accelerometers for dairy cattle.

Associations between lying behavior and activity and hypocalcemia in grazing dairy cows during the transition period

Hypocalcemia is a common metabolic disorder of transition dairy cows that is considered a gateway disease, increasing the risk of other health disorders and reducing cow performance. Clinical milk fever is associated with long periods of recumbency, and it is plausible that cows experiencing non-paretic hypocalcemia may spend more time lying; hence, lying behavior and activity measures may be useful in identifying at-risk cows. The objective of this study was to describe associations among blood calcium (Ca) status at calving and lying behavior and activity measures during the transition period in grazing dairy cows. Blood was sampled on the day of calving (d 0), and d 1, 2, 3, and 4 postcalving, and analyzed for total plasma Ca concentration. Twenty-four multiparous Holstein-Friesian and Holstein-Friesian × Jersey grazing dairy cows were classified, retrospectively, as clinically hypocalcemic (CLIN; blood Ca ≤ 1.4 mmol/L at 1 or more consecutive samplings within 48 h postcalving, but without parturient paresis). These cows were pair-matched (using milk production potential from their estimated breeding value for milk protein, mean body weight at wk -5 and -6 precalving, and, where possible, parity) with 24 cows classified as subclinically hypocalcemic (SUB; blood Ca > 1.4 and < 2.0 mmol/L at 2 consecutive samplings within 48 h postcalving), and 24 cows classified as normocalcemic (NORM; blood Ca ≥ 2.0 mmol/L at 3 consecutive samplings within 72 h postcalving). Lying behavior and activity were monitored using triaxial accelerometers from -21 to +35 d relative to calving. Data were summarized to calculate daily lying time (h/d), daily number of lying bouts (LB; no./d), mean LB duration (min/bout), and the number of steps taken (steps/d). On d 0, the CLIN group were less active and spent approximately 2.6 h longer lying than the SUB and NORM groups, particularly between 0200 and 1400 h. On d 0, the NORM group had fewer LB (16.3/d) than the SUB and CLIN groups (18.2 and 19.2/d, respectively). These differences in behavior were no longer detected 2 d postcalving, and no further differences were observed. The day before calving, the CLIN group spent 1.4 h longer lying down than did the SUB and NORM groups. Further, the relative change in steps from a precalving baseline period (d -14 to -7) until d 0 was positively, linearly associated with blood Ca concentration within 24 h postcalving. Future work should consider daily and temporal changes in behavior in individual cows to determine the potential for these measures to allow early detection of hypocalcemia.

Feeding synthetic zeolite to transition dairy cows alters neutrophil gene expression

Synthetic zeolites are used to control the availability of dietary minerals (e.g., Ca, Mg, and P) in dairy cows. Due to calcium demand increasing with lactation onset, most cows become hypocalcemic immediately postpartum, which likely contributes to poorer immune function because calcium is important for immune cell signaling. To overcome postpartum hypocalcemia, we fed transition cows synthetic zeolite A (sodium aluminosilicate) precalving and hypothesized that it would alter calcium and thus neutrophil function during the transition period. Multiparous Holstein-Friesian cows in late gestation were randomly allocated to an untreated control group (n = 10) or a treatment group in which each cow received 500 g of zeolite A daily (n = 10) for 14 d prior to the expected calving date (actual duration = 17 ± 3 d prepartum). The cows grazed pasture, and each was supplemented with 2 kg/d of maize silage (dry matter basis), with or without zeolite, until calving. Blood samples for neutrophil isolation and analysis of plasma indicators of mineral status, energy status, liver function, and inflammation were collected pretreatment (covariate; d -19); on d -14 and -7 precalving; on the day of calving (d 0); and on d 1, 4, 7, and 28 postcalving. Neutrophils were isolated and gene expression was analyzed using microfluidic gene expression arrays. Neutrophil respiratory burst was assessed using stimulation with phorbol 12-myristate 13-acetate and flow cytometry. Plasma calcium and phosphorus revealed a treatment by time interaction; cows offered zeolite had greater plasma calcium concentrations at d 0, 1, and 4 postcalving and plasma phosphorus concentrations were lower in zeolite-treated cows during the precalving period until d 1 postcalving compared with control animals. Zeolite treatment downregulated neutrophil gene expression of CXCR4 and S100A8 and tended to lower gene expression for other immune mediators (CXCR1, IFNG, S100A12, and S100A9) compared with the control. Zeolite treatment did not affect neutrophil respiratory burst or expression of the other genes investigated. Plasma concentrations of cytokine IL-6 were reduced with zeolite treatment, which was most evident immediately postcalving (d 0, 1, and 7). Overall, feeding zeolite precalving had few effects on neutrophil gene expression and function; however, the lower gene expression of neutrophil inflammatory mediators may be due to altered availability of dietary minerals prepartum and indicates that zeolite A may control inflammation during the transition period.

Lying behavior and activity during the transition period of clinically healthy grazing dairy cows

Lying behavior and activity may provide useful information for the prediction of an imminent calving and the health of transition dairy cows; however, it is important first to understand what constitutes typical lying behavior and activity because this has not been defined for grazing dairy cows during the transition period. Our objective was to describe changes in lying behavior and activity in grazing dairy cows during the transition period using varying phenotypes typical of commercial dairy herds under grazing systems. Behavior data from IceTag or IceQube (IceRobotics, Edinburgh, Scotland) triaxial accelerometers were collected for 310 cow parities from multiparous, mixed-age (mean ± standard deviation; 4.5 ± 1.65 yr), and mixed-breed [Holstein-Friesian (HF), n = 216; and HF × Jersey, n = 94] grazing dairy cows from 4 parent experiments. The IceTags or IceQubes captured lying and activity data during the transition period (-21 to 34 d relative to calving) to allow the calculation of daily lying time (h/d), daily lying bouts (LB; no./d), mean LB duration (min/bout), and the number of steps taken (steps/d). Lying behavior and activity were analyzed using a repeated measures ANOVA during 3 periods: PRE (-21 to -3 d), POST (3 to 21 d), and the day of calving (d 0). Lying time was lower on d 0 (7.25 h/d) compared with PRE and POST lying times (10.3 and 8.58 h/d, respectively), with more frequent LB on d 0 (12.9 no./d) compared with the PRE and POST daily LB (8.15 vs. 7.74 no./d). Cows took more steps POST (4,424 steps/d) compared with d 0 and PRE (4,105 and 2,289 steps/d, respectively). Regression analysis determined that daily lying time decreased substantially from -3 to 0 d (slope = -1.03 ± 0.07 h/d) and from -2 and -1 d for daily LB (slope = 5.09 ± 0.54 no./d), which may be due to the calving event itself but also reflect restlessness. Daily lying time, daily LB, LB duration, and number of steps taken were substantially altered at the time of the calving event in grazing dairy cows. Cows were more active, spent less time lying, and took more steps postcalving compared with precalving, and it appears that this behavior may largely be due to activity associated with twice daily milking. Mean lying behavior and activity measures were more highly variable across individuals than across groups. Information available via activity monitors may contribute to the improvement of individual management of transition dairy cows, and this research provides a benchmark for typical changes in behavior during the transition period in grazing systems.

A redefinition of the modeled responses of mammary glands to once-daily milking

Milking cows once daily is a management tool that has been implemented to improve physical and financial results of seasonal pasture-based dairy farms. The Molly cow model integrates physiology and metabolism of dairy cattle; however, milk production during short-term changes in milking frequency (e.g., 1× milking) is not well represented. The model includes a representation of variable rates of cell quiescence and death. However, the rate constants governing cell death and the return of quiescent to active cells are not affected by milking frequency. An empirical assessment of the problem was conducted, and it was hypothesized that changing the current representation of the rate of cell death in response to short-term 1× milking would more accurately represent active and quiescent cells and improve predictions of milk production. An extra senescent cell flux was added to account for cell loss during periods of 1× milking. Additional changes included a gradual decline in the rate of 1× stimulated senescence during 1× milking, and a structural change in cell cycling between active and quiescent cells during and after short-term 1× milking. Data used for parameter estimation were obtained from 5 studies where 1× milking or different feeding strategies were tested. Parameter estimates of cell loss indicated that 1× milking would affect a small proportion of quiescent cells to cause extra cell death. This added cell senescence was influenced by the length of 1× milking such that cell senescence peaked on d 1 of 1× milking and decayed from that point. The new structure in the model includes a variable rate of cell death in response to 1× milking and a gradual rate of return of quiescent cells back to the active pool in response to switching to 2× milking after short-term 1× milking. Root mean square errors, mean bias, and slope bias declined by at least 50% for predictions of energy-corrected milk yield and fat percent. The model showed quantitative agreement with production data from short-term 1× milking. The accuracy of predictions was improved and the error was reduced by implementing modifications in the model in response to changes in milking frequency.

Prediction of blood β-hydroxybutyrate content and occurrence of hyperketonemia in early-lactation, pasture-grazed dairy cows using milk infrared spectra

The objective of this study was to evaluate the ability of milk infrared spectra to predict blood β-hydroxybutyrate (BHB) concentration for use as a management tool for cow metabolic health on pasture-grazed dairy farms and for large-scale phenotyping for genetic evaluation purposes. The study involved 542 cows (Holstein-Friesian and Holstein-Friesian × Jersey crossbreds), from 2 farms located in the Waikato and Taranaki regions of New Zealand that operated under a seasonal-calving, pasture-based dairy system. Milk infrared spectra were collected once a week during the first 5 wk of lactation. A blood "prick" sample was taken from the ventral labial vein of each cow 3 times a week for the first 5 wk of lactation. The content of BHB in blood was measured immediately using a handheld device. After outlier elimination, 1,910 spectra records and corresponding BHB measures were used for prediction model development. Partial least square regression and partial least squares discriminant analysis were used to develop prediction models for quantitative determination of blood BHB content and for identifying cows with hyperketonemia (HYK). Both quantitative and discriminant predictions were developed using the phenotypes and infrared spectra from two-thirds of the cows (randomly assigned to the calibration set) and tested using the remaining one-third (validation set). A moderate accuracy was obtained for prediction of blood BHB. The coefficient of determination (R²) of the prediction model in calibration was 0.56, with a root mean squared error of prediction of 0.28 mmol/L and a ratio of performance to deviation, calculated as the ratio of the standard deviation of the partial least squares model calibration set to the standard error of prediction, of 1.50. In the validation set, the R² was 0.50, with root mean squared error of prediction values of 0.32 mmol/L, which resulted in a ratio of performance to deviation of 1.39. When the reference test for HYK was defined as blood concentration of BHB ≥1.2 mmol/L, discriminant models indicated that milk infrared spectra correctly classified 76% of the HYK-positive cows and 82% of the HYK-negative cows. The quantitative models were not able to provide accurate estimates, but they could differentiate between high and low BHB concentrations. Furthermore, the discriminant models allowed the classification of cows with reasonable accuracy. This study indicates that the prediction of blood BHB content or occurrence of HYK from milk spectra is possible with moderate accuracy in pasture-grazed cows and could be used during routine milk testing. Applicability of infrared spectroscopy is not likely suited for obtaining accurate BHB measurements at an individual cow level, but discriminant models might be used in the future as herd-level management tools for classification of cows that are at risk of HYK, whereas quantitative models might provide large-scale phenotypes to be used as an indicator trait for breeding cows with improved metabolic health.

Fertility and the transition dairy cow

The transition from pregnancy to lactation (i.e. the transition period) is a time of significant metabolic challenge, with a several-fold increase in a cow's requirement for energy, protein and minerals within days of calving. A successful transition involves the initiation and coordination of changes in multiple tissues that facilitate the provision of these nutrients to the cow and, more specifically, to the mammary gland, often at the considerable expense of other tissues. Failure to coordinate the necessary changes effectively results in transition period maladaptation, which can broadly be grouped into three categories: (1) negative energy balance and metabolic diseases associated with energy metabolism; (2) immune dysfunction and inflammation; and (3) metabolic diseases associated with mineral deficiency. Because reinitiation of ovarian activity, follicle recruitment, ovulation, fertilisation and, potentially, even maternal recognition of pregnancy and implantation occur against the backdrop of this metabolic and immunological disturbance in early lactation, the role of nutrition in ensuring a smooth transition between the pregnant and lactating state is important. In this paper we integrate recent research findings with previous knowledge of the interaction between transition cow metabolism and nutrition and reproductive outcomes, and offer new insights into key elements of successful cow management to avoid transition 'maladaptation' and improve pregnancy rates.

Lactation traits associated with short- and long-term once-daily milking performance in New Zealand crossbred dairy cattle

The main objectives of this study were to establish the relative value of milk yields under twice-daily milking (TDM) as a predictor of yield and yield loss under once-daily milking (ODM), and to understand the role of residual milk and udder storage capacity-related traits in regulating yield and yield loss during ODM. A Holstein-Friesian × Jersey crossbred herd was established over 2 seasons (years), as 2 individual cohorts on the same farm, managed on a pasture-based system over 4 lactations. Short-term (1-wk) ODM studies, with a starting total of 690 cows, were undertaken in mid- and late-lactation in lactation 2 and in mid-lactation in lactation 3 for each cohort. A 10-wk study of ODM performance began in mid-lactation in lactation 3, whereas lactation 4 was a full-lactation assessment of ODM. In the short-term studies, milk yield under ODM was well predicted (R(2)=0.7 to 0.8 in 5 of 6 studies) by the daily yield under TDM in the week before ODM. Yield loss (kg/d) increased with increasing milk yield and with increasing somatic cell count (SCC), although predictions were relatively poor (R(2)=0.09 to 0.30). Yield loss (%) decreased with increasing TDM yield in 3 of the 6 studies and was positively correlated with SCC during ODM. Nevertheless, ODM yield loss, in absolute or percentage terms, was a poorly repeatable trait in grazing cows. Part of the variation in yield loss percentage (30%) was positively associated with residual milk (%), measured pretrial, during measurement of functional udder capacity in lactation 3. Total production (kg of milk) over the full-lactation ODM study in lactation 4 was correlated with total production in the 10-wk trial in lactation 3 (r=0.72 and 0.63 for cohorts 1 and 2, respectively). Identifying the highest- and lowest-producing 10% of animals during the full lactation of ODM indicated that poor production was associated with high yields of residual milk (measured in lactation 3) and, conversely, high production was associated with low yields of residual milk, relative to the other 80% of animals. These same "high" and "low" production groups from lactation 4 had similar differences in performance in the earlier short-term studies and a larger or smaller percentage yield loss associated with the residual milk measurement. Breeding strategies for ODM may benefit, therefore, from greater emphasis on selecting for a low residual milk fraction to optimize milking performance. Nevertheless, the level of milk production under TDM is a strong phenotypic predictor of milk production under ODM.

Burkitt's lymphoma-associated c-Myc mutations converge on a dramatically altered target gene response and implicate Nol5a/Nop56 in oncogenesis

Burkitt’s Lymphomas (BLs) acquire consistent point mutations in a conserved domain of Myc, Myc Box I. We report that the enhanced transforming activity of BL-associated Myc mutants can be uncoupled from loss of phosphorylation and increased protein stability. Furthermore, two different BL-associated Myc mutations induced similar gene expression profiles independently of T58 phosphorylation, and these profiles are dramatically different from MycWT. Nol5a/Nop56, which is required for rRNA methylation, was identified as a gene hyperactivated by the BL-associated Myc mutants. We show that Nol5a is necessary for Myc-induced cell transformation, enhances MycWT-induced cell transformation, and increases the size of MycWT induced tumors. Thus, Nol5a expands the link between Myc-induced regulation of nucleolar target genes which are rate-limiting for cell transformation and tumor growth.

Evaluation of cinacalcet HCl treatment after kidney transplantation

BACKGROUND

Hyperparathyroidism often remains or develops after kidney transplantation. Vitamin D sterol used as treatment for an elevated parathyroid hormone (PTH) level and associated bone disease may be contraindicated due to hypercalcemia. The calcimimetic cinacalcet HCl (cinacalcet), which lowers PTH and calcium (Ca) in chronic kidney disease patients, may represent an alternate therapeutic modality.

METHODS

This multicenter, retrospective, observational study examined 41 kidney transplant patients receiving cinacalcet for ≥3 months starting ≥3 months posttransplantation. Levels of intact PTH, Ca, and phosphorus (P) were examined during the assessment phase (3-6 months after initiation).

RESULTS

Median PTH decreased 21.8% during the assessment phase (P < .001), with 32.5% of patients exhibiting a ≥30% decrease in PTH from baseline. Median Ca decreased 6.8% (P < .0001). Median serum P rose 10.0% (P = .0124), but remained within normal limits. The estimated glomerular filtration rate was stable throughout the study.

CONCLUSIONS

Cinacalcet may be useful for the treatment of hyperparathyroidism after kidney transplantation. Randomized, prospectively designed clinical trials are required to confirm these results.

Iatrogenic femoral artery pseudoaneurysms--a review of current methods of diagnosis and treatment

The common femoral artery is commonly used as arterial access for a wide range of radiological and cardiological procedures. Pseudoaneurysm formation is the most common arterial complication of femoral artery catheterization, and is diagnosed using colour Doppler ultrasound. Ultrasound-guided thrombin injection has replaced ultrasound-guided compression as the first-line treatment. The practicalities of thrombin injection (technique and types of thrombin available) and other treatment options are discussed. Awareness of pseudoaneurysm formation and the treatment options allows prompt diagnosis and successful treatment.

Survey for papillomatous digital dermatitis in Australian dairy cattle

OBJECTIVE

To determine whether Treponema-associated papillomatous digital dermatitis (PDD) occurs in Australian dairy cattle.

DESIGN

Mail-out questionnaire and histological and bacteriological examination of biopsy tissue from suspect PDD lesions.

PROCEDURE

The questionnaire was mailed to 375 veterinarians to evaluate their knowledge of PDD, determine if they had observed the disease in Australian dairy cattle, and to request biopsy material from suspicious cases. Biopsies were examined for histological and bacteriological evidence of PDD, including for the presence of spirochaetes.

RESULTS

Eighty-eight replies to the questionnaire were received (23.5%). Of 52 respondents who were aware of PDD as a possible cause of lameness, 26 reported observing the condition in Australian cattle. Of 32 respondents who were unaware of the condition, 6 reported observing lesions that might have been PDD. The majority of reports of PDD-like lesions came from the southern Australian states, the condition occurring during periods of high rainfall and proving responsive to topical or parenteral application of antimicrobials. Biopsies from five erosive lesions showed histological similarity to PDD whereas biopsies from five proliferative lesions were consistent with chronic inflammation, fibroma or cutaneous papilloma. The presence of spirochaetes was not demonstrated in any of the lesions by histological or bacteriological methods.

CONCLUSION

Anecdotal reports and analysis of biopsy material confirm that a condition similar to PDD does occur sporadically in dairy cattle in southern Australia. However, this condition has so far not been shown to be associated with the presence of spirochaetes in the lesions.

Nested deletions of the SRL pathogenicity island of Shigella flexneri 2a

In this study, we determined the boundaries of a 99-kb deletable element of Shigella flexneri 2a strain YSH6000. The element, designated the multiple-antibiotic resistance deletable element (MRDE), had recently been found to contain a 66-kb pathogenicity island (PAI)-like element (designated the SRL PAI) which carries the Shigella resistance locus (SRL), encoding resistance determinants to streptomycin, ampicillin, chloramphenicol, and tetracycline. The YSH6000 MRDE was found to be flanked by two identical IS91 elements present at the S. flexneri homologs of the Escherichia coli genes putA and mdoA on NotI fragment D. Sequence data from two YSH6000-derived MRDE deletants, YSH6000T and S2430, revealed that deletion of the MRDE occurred between the two flanking IS91 elements, resulting in a single IS91 element spanning the two original IS91 loci. Selection for the loss of tetracycline resistance confirmed that the MRDE deletion occurred reproducibly from the same chromosomal site and also showed that the SRL PAI and the SRL itself were capable of independent deletion from the chromosome, thus revealing a unique set of nested deletions. The excision frequency of the SRL PAI was estimated to be 10(-5) per cell in the wild type, and mutation of a P4-like integrase gene (int) at the left end of the SRL PAI revealed that int mediates precise deletion of the PAI.

Ferric dicitrate transport system (Fec) of Shigella flexneri 2a YSH6000 is encoded on a novel pathogenicity island carrying multiple antibiotic resistance genes

Iron uptake systems which are critical for bacterial survival and which may play important roles in bacterial virulence are often carried on mobile elements, such as plasmids and pathogenicity islands (PAIs). In the present study, we identified and characterized a ferric dicitrate uptake system (Fec) in Shigella flexneri serotype 2a that is encoded by a novel PAI termed the Shigella resistance locus (SRL) PAI. The fec genes are transcribed in S. flexneri, and complementation of a fec deletion in Escherichia coli demonstrated that they are functional. However, insertional inactivation of fecI, leading to a loss in fec gene expression, did not impair the growth of the parent strain of S. flexneri in iron-limited culture media, suggesting that S. flexneri carries additional iron uptake systems capable of compensating for the loss of Fec-mediated iron uptake. DNA sequence analysis showed that the fec genes are linked to a cluster of multiple antibiotic resistance determinants, designated the SRL, on the chromosome of S. flexneri 2a. Both the SRL and fec loci are carried on the 66,257-bp SRL PAI, which has integrated into the serX tRNA gene and which carries at least 22 prophage-related open reading frames, including one for a P4-like integrase. This is the first example of a PAI that carries genes encoding antibiotic resistance and the first report of a ferric dicitrate uptake system in Shigella.

A calcimimetic agent lowers plasma parathyroid hormone levels in patients with secondary hyperparathyroidism

BACKGROUND

The calcimimetic agent R-568 lowers plasma parathyroid hormone (PTH) levels in hemodialysis patients with mild secondary hyperparathyroidism, but its efficacy in those with more severe secondary hyperparathyroidism has not been studied.

METHODS

Twenty-one patients undergoing hemodialysis three times per week with plasma PTH levels between 300 and 1200 pg/mL were randomly assigned to 15 days of treatment with either 100 mg of R-568 (N = 16) or placebo (N = 5). Plasma PTH and blood ionized calcium levels were measured at intervals of up to 24 hours after oral doses on days 1, 2, 3, 5, 8, 11, 12, and 15.

RESULTS

Pretreatment PTH levels were 599 +/- 105 (mean +/- SE) and 600 +/- 90 pg/mL in subjects given R-568 or placebo, respectively, and values on the first day of treatment did not change in those given placebo. In contrast, PTH levels fell by 66 +/- 5%, 78 +/- 3%, and 70 +/- 3% at one, two, and four hours, respectively, after initial doses of R-568, remaining below pretreatment values for 24 hours. Blood ionized calcium levels also decreased after the first dose of R-568 but did not change in patients given placebo. Despite lower ionized calcium concentrations on both the second and third days of treatment, predose PTH levels were 422 +/- 70 and 443 +/- 105 pg/mL, respectively, in patients given R-568, and values fell each day by more than 50% two hours after drug administration. Predose PTH levels declined progressively over the first nine days of treatment with R-568 and remained below pretreatment levels for the duration of study. Serum total and blood ionized calcium concentrations decreased from pretreatment levels in patients given R-568, whereas values were unchanged in those given placebo. Blood ionized calcium levels fell below 1.0 mmol/L in 7 of 16 patients receiving R-568; five patients withdrew from study after developing symptoms of hypocalcemia, whereas three completed treatment after the dose of R-568 was reduced.

CONCLUSIONS

The calcimimetic R-568 rapidly and markedly lowers plasma PTH levels in patients with secondary hyperparathyroidism caused by end-stage renal disease.

Milk whey protein concentration and mRNA associated with beta-lactoglobulin phenotype

Two common genetic variants of β-lactoglobulin (β-lg), A and B, exist as co- dominant alleles in dairy cattle (Aschaffenburg, 1968). Numerous studies have shown that cows homozygous for β-lg A have more β-lg and less α-lactalbumin (α-la) and casein in their milk than cows expressing only the B variant of β-lg (Ng-Kwai-Hang et al. 1987; Graml et al. 1989; Hill, 1993; Hill et al. 1995, 1997). These differences have a significant impact on the processing characteristics of the milk. For instance, the moisture-adjusted yield of Cheddar cheese is up to 10% higher using milk from cows of the β-lg BB phenotype compared with milk from cows expressing only the A variant (Hill et al. 1997). All these studies, however, describe compositional differences associated with β-lg phenotype in established lactation only. No information is available on the first few weeks of lactation, when there are marked changes in the concentrations of β-lg and α-la (Pérez et al. 1990).

Mapping access to food in a deprived area: the development of price and availability indices

OBJECTIVE

To develop and map indices to illustrate variation in the cost and availability of healthy food.

DESIGN

Two contiguous wards in London were selected by virtue of their high Carstairs deprivation scores. A 2-km area was defined around a randomly chosen central point. All retail outlets selling food within the area were visited and their location recorded. A list of foods, acceptable to the local ethnically diverse population, which met current dietary guidelines, was devised. Data on the availability and price of 71 food items were collected. Indices were developed using SPSS and mapped using Geographic Information System (GIS) software.

RESULTS

Information on availability and prices were collected from 199 outlets. The mean price index shows how expensive a shop is relative to other shops in the area. The least cost index shows the relative expense of a shop using the cheapest ways of buying their range of foods. Shorthand indices were tested, using data on 19 of the 71 prices. Availability indices are also discussed, including a green availability index and a fresh green availability index. Illustrative maps of the shop locations and the mean price index and fresh green availability index are shown.

CONCLUSIONS

Data can be collected and indices developed which indicate geographic variation in shop 'expensiveness', and in the price and availability of healthy food. GIS software can be used to map these indices, to identify areas with high food prices or low availability.

A randomized phase 3 study of peripheral blood progenitor cell mobilization with stem cell factor and filgrastim in high-risk breast cancer patients

This randomized study compared the number of leukaphereses required to collect an optimal target yield of 5 x 10(6) CD34(+) peripheral blood progenitor cells/kg, using either stem cell factor (SCF) at 20 micrograms/kg/d in combination with Filgrastim at 10 micrograms/kg/d or Filgrastim alone at 10 micrograms/kg/d, from 203 patients with high-risk stage II, III, or IV breast cancer. Leukapheresis began on day 5 of cytokine administration and continued daily until the target yield of CD34(+) cells had been reached or a maximum of 5 leukaphereses performed. By day 5 of leukapheresis, 63% of the patients treated with SCF plus Filgrastim (n = 100) compared with 47% of those receiving Filgrastim alone (n = 103) reached the CD34(+) cell target yield. There was a clinically and statistically significant reduction (P <.05) in the number of leukaphereses required to reach the target yield for the patients receiving SCF plus Filgrastim (median, 4 leukaphereses) compared with patients receiving Filgrastim alone (median, 6 or more leukapherses; ie, <50% of patients reached the target in 5 leukaphereses). All patients receiving SCF were premedicated with antihistamines, albuterol, and pseudoephedrine. Treatment was safe, generally well tolerated, and not associated with life-threatening or fatal toxicity. In conclusion, SCF plus Filgrastim is a more effective peripheral blood progenitor cell (PBPC)-mobilization regimen than Filgrastim alone. In addition to the potential for reduced leukapheresis-related morbidity and costs, SCF offers additional options for obtaining cells for further graft manipulation.

Pressure sore prevention in hospital patients: a clinical audit

Pressure sores cause significant mortality and morbidity as well as being a financial burden on health-care services. Reduction of pressure sore incidence is a Department of Health priority. Pressure sores are accepted as largely preventable complications of illness and disability and the means to achieve prevention are available. The aim of this clinical audit was to identify potential contributing factors to pressure sore acquisition in an acute hospital setting. The results suggest that substantial changes in the approach to clinical management may be needed.

No evidence for basolateral secretion of milk protein in the mammary gland of lactating goats

Recent research suggests that a small percentage of milk proteins may be secreted basolaterally, which would have implications for our work on the permeability of tight junctions in the mammary epithelium. In our work, the presence of alpha-lactalbumin (LA) or lactose in plasma is used as an indicator of permeability. The aim of this study was to examine basolateral secretion by determining the presence of milk proteins in efferent mammary lymph. Five Saanen goats were fitted with mammary lymph catheters and were administered intramammary isosmotic bolus infusions of sucrose control solutions or ethylene glycolbis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid to induce leaky tight junctions. Lymph samples were collected before and approximately 5 h after infusion. Lymph was analyzed by Western blotting for the presence of alpha-casein (CN), beta-CN, and alpha-LA No alpha-CN or beta-CN was detected in lymph, but alpha-LA was detected in all lymph samples. Moreover, the signal was much stronger in samples from goats that were treated with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, and concentrations of alpha-LA in lymph were significantly increased with this treatment. These changes and the absence of casein in lymph suggest increased permeability of tight junctions rather than basolateral secretion. In summary, these data do not support basolateral secretion.

Peripheral blood progenitor cell mobilization using stem cell factor in combination with filgrastim in breast cancer patients

The safety and optimal dose and schedule of stem cell factor (SCF) administered in combination with filgrastim for the mobilization of peripheral blood progenitor cells (PBPCs) was determined in 215 patients with high-risk breast cancer. Patients received either filgrastim alone (10 microg/kg/d for 7 days) or the combination of 10 microg/kg/d filgrastim and 5 to 30 microg/kg/d SCF for either 7, 10, or 13 days. SCF patients were premedicated with antiallergy prophylaxis. Leukapheresis was performed on the final 3 days of cytokine therapy and, after high-dose chemotherapy and infusion of PBPCs, patients received 10 microg/kg/d filgrastim until absolute neutrophil count recovery. The median number of CD34+ cells collected was greater for patients receiving the combination of filgrastim and SCF, at doses greater than 10 microg/kg/d, than for those receiving filgrastim alone (7.7 v 3.2 x 10(6)/kg, P < .05). There were significantly (P < .05) more CD34+ cells harvested for the 20 microg/kg/d SCF (median, 7.9 x 10(6)/kg) and 25 microg/kg/d SCF (median, 13.6 x 10(6)/kg) 7-day combination groups than for the filgrastim alone patients (median, 3.2 x 10(6)/kg). The duration of administration of SCF and filgrastim (7, 10, or 13 days) did not significantly affect CD34+ cell yield. Treatment groups mobilized with filgrastim alone or with the cytokine combination had similar hematopoietic engraftment and overall survival after PBPC infusion. In conclusion, the results of this study indicate that SCF therapy enhances CD34+ cell yield and is associated with manageable levels of toxicity when combined with filgrastim for PBPC mobilization. The combination of 20 microg/kg/d SCF and 10 microg/kg/d filgrastim with daily apheresis beginning on day 5 was selected as the optimal dose and schedule for the mobilization of PBPCs.

Occlusal indices revisited

With the increased interest in measuring the need for orthodontic treatment and the quality of the outcome of orthodontic care, the difficulties in using Grainger's Treatment Priority Index (TPI) to screen children in their tenth year is considered. The first part of the study investigated the level of validity of the TPI using 137 study models and three orthodontists. In the light of the results obtained, the TPI was modified. The clinical judgement of a further two orthodontists was compared with the scores obtained form the modified TPI, using another 121 study models. Three Community Dental Officers were employed initially to assess the training needs for personnel who were not trained in orthodontics. A further five Community Dental Officers were involved in the final training programmes. It was concluded that it will be very difficult to produce an index which considers all aspects of malocclusion and which can be used consistently by personnel untrained in orthodontics.

Amygdaloid influences on brain-stem neurones in the rabbit

1. Electrical stimulation of the central nucleus of the amygdala in the urethane or alpha-chloralose anaesthetized rabbit evokes a bradycardia with a rapid onset and a concomitant fall in arterial blood pressure. 2. Extracellular neuronal activity was recorded in the ipsilateral nucleus tractus solitarius and dorsal vagal nucleus whilst stimulating the ipsilateral central nucleus of the amygdala, the aortic and vagus nerves. 3. A total of 213 neurones were activated by stimulation of at least one of these inputs. 93 of these neurones received a marked excitatory input from the central nucleus with a wide range of latencies (2-100 ms). 50 of these cells also received inputs from either the aortic or vagus nerves, or both. 4. The activity of 42 vagal preganglionic neurones was recorded in the dorsal vagal nucleus of which 22 had properties typical of cardioinhibitory neurones. 9 of these vagal motoneurones received inputs from the central nucleus with latencies between 2 and 100 ms. Of these, 5 had physiological properties indicating they were cardio-inhibitory neurones. 5. We conclude that neurones in the nucleus tractus solitarius and dorsal vagal nucleus can be influenced by descending inputs arising from the central nucleus of the amygdala. Some of these neurones are also likely to be influenced by afferents innervating the thoracic viscera and arterial baroreceptors. The implications of these observations on the role of forebrain-brain-stem interactions in cardiovascular control are discussed.

The effects of a multicomponent smoking cessation program with chronic obstructive pulmonary disease outpatients

While a number of multicomponent treatments have been utilized to control smoking, many of these are not suitable for some populations such as chronic obstructive pulmonary disease (COPD) patients because they consist of aversion procedures which can stress the body's cardiovascular system. Little research has been published regarding nonaversive approaches to smoking control in a COPD patient population. This study examined the long-term effects of a nonaversive multicomponent smoking cessation program consisting of brand fading and stimulus control with a COPD outpatient population as measured by self-report. Using four COPD outpatients, this study employed a multiple baseline design across subjects for a visual analysis of treatment effects. At 3- and 6-month follow-up, one subject had quit smoking. Two subjects who continued to smoke reduced their smoking frequency and drastically reduced their nicotine intake by brand fading to a cigarette containing lower amounts of nicotine. A fourth subject returned to her original brand of cigarettes, although she reduced her smoking frequency. Collaborators and measurements of thiocyanate levels were used as reliability checks on subjects' self-report.

Comparison of dopamine and dobutamine therapy during intraaortic balloon pumping for the treatment of postcardiotomy low-output syndrome

Treatment of postcardiotomy low-output syndrome includes intraaortic balloon pumping (IABP), volume loading, pharmacological afterload reduction, and stimulation with an inotropic agent. This study compares the effectiveness of combined nitroprusside and dopamine therapy and nitroprusside and dobutamine therapy in 12 patients requiring IABP postoperatively. Serial hemodynamic measurements were made before and during infusion of nitroprusside and after administration of the combined therapy (N = 6 in each group). Prior to pharmacological therapy, cardiac index was 1.47 +/- 0.31 L/min/m2 and systemic vascular resistance (SVR) was 3,114 +/- 1,350 dynes sec cm-5 in patients subsequently given dopamine, and 1.59 +/- 0.38 L/min/m2 and 2,661 +/- 405 dynes sec cm-5, respectively, in those given dobutamine. With infusion of nitroprusside, both groups showed significant reduction in SVR. Nitroprusside plus either inotropic agent resulted in augmentation of cardiac index and an additional reduction in SVR, both changes being greater in the group given dopamine. Larger doses of dobutamine than dopamine were needed to achieve similar hemodynamic improvement. We conclude that the addition of an inotropic agent to vasodilator therapy during IABP results in a greater increase in cardiac index and a greater decrease in afterload than a vasodilator alone. In addition to its beneficial effect on renal perfusion at the dose required to effect these improvements, dopamine appears a better inotropic agent than dobutamine for postcardiotomy low-output syndrome.

The feasibility and validity of orthodontic screening of children in their tenth year

The study set out to investigate the problems of the implementation of the Court Report's suggestion that every child in its tenth year be screened for orthodontic treatment by "a dentist with special training in orthodontics' using Grainger's Treatment Priority Index (TPI). The study was divided into two parts. The standardization exercises used 31 orthodontic models of children in their tenth year. The problem of examiner variability, using a Community Dental Officer instead of an orthodontist and of bias that the TPI might have were examined. The main study involved the examination of 362 children in ten separate schools in Oxfordshire and investigated the problem of orthodontic screening at annual school inspections. The findings showed that the TPI may be able to provide a method for screening children in their tenth year if the weights of the clinical entities which are reducing the level of validity of the TPI are identified. The problem of scoring tooth displacements consistently would have to be taken into consideration when training personnel to use the TPI.

Development and evaluation of a long-term, implantable, electrically actuated left ventricular assist system: THI/Gould LVAS

A long-term, implantable, electrically actuated left ventricular assist system (THI/Gould LVAS) is being developed and characterized in vitro and in vivo for utilization in patients with end-stage heart disease. This system consists of five major components: a long-term, implantable blood pump (THI E-type ALVAD); an electrical-mechanical energy converter (Gould Model V); a control unit with batteries; a volume compensation system; and an external power supply and monitoring unit. Two of these components (blood pump and electrical-mechanical energy converter) have been integrated, and are undergoing chronic in vivo evaluations in calves. Thus far, 44 pneumatically and electrically actuated THI/Gould LVAS evaluations have been performed. This experience has resulted in greater than 6.5 years of actuation in vivo, with durations exceeding 1 year. System in vivo performance in terms of durability, mechanical reliability, hemodynamic effectiveness, and biocompatibility has been satisfactory. Demonstration of long-term (2-year) effectiveness in supporting the circulation is the ultimate goal.

Calcification in chronically-implanted blood pumps: experimental results and review of the literature

Blood compatibility is a major objective in the development of long-term, implantable circulatory assist (left ventricular assist devices) and replacement (total artificial heart) devices. An important problem in experimental studies in animals has been the propensity for calcification to occur at the blood/material interface. Presented is a summary of our experience (27 studies) with blood pump calcification and a review of the current literature regarding this complication.

Combined use of dopamine and nitroprusside therapy in conjunction with intra-aortic balloon pumping for the treatment of postcardiotomy low-output syndrome

Intra-aortic balloon pumping (IABP) has been utilized in our institution in over 600 patients for the treatment of postcardiotomy low-output syndrome, with a 59% survival rate. Volume loading and pharmacologic treatment have played integral roles in the overall treatment of this syndrome. This investigation documents the hemodynamic effectivenss of combined nitroprusside/dopamine therapy in patients who required IABP for weaning from cardiopulmonary bypass. Serial hemodynamic measurements were made before and during infusion of nitroprusside (0.5 to 5.0 microgram/kg/min) and after combined nitroprusside/dopamine (7.5 micrograms/kg/min) therapy in 10 patients during IABP. Prior to pharmacologic therapy, cardiac index was 1.6 +/- 0.4 L/min/m2 and systemic vascular resistance (SVR) was 2,774 +/- 932 dynes sec cm-5. After nitroprusside infusion, cardiac index increased to 1.8 +/- 0.5 L/min/m2 (NS) and SVR decreased to 1,957 +/- 791 dynes sec cm-5 (p less than 0.01). The simultaneous infusion of nitroprusside and dopamine resulted in further augmentation of cardiac index to 2.5 +/- 0.5 L/min/m2 (p less than 0.01) and an additional reduction of SVR to 1,439 +/- 358 dynes sec cm-5 (p less than 0.02). In addition, pressure-rate-product, an index of myocardial oxygen demand, was decreased by nitroprusside (p less than 0.02) but was not significantly altered by both agents. This study provides a rationale for the combined use of nitroprusside/dopamine in postcardiotomy low-output syndrome necessitating IABP when SVR is greater than 2,000 dynes sec cm-5 and cardiac index is less than 2.0 L/min/m2.

Development and evaluation of electrically actuated abdominal left ventricular assist systems for long-term use

A long-term, totally implantable, electrically actuated, abdominally positioned left ventricular assist system (ALVAS) is being developed, characterized in vitro, and evaluated in vivo for utilization in patients with end-stage cardiac failure refractory to conventional therapeutic techniques. The first two major subsystems of the ALVAS (the pusher-plate blood pump and electrical-mechanical energy converters) have been integrated and are undergoing in vitro characterization and long-term in vivo evaluations in calves. Duration of these studies has exceeded 6 months. System performance in terms of hemodynamic effectiveness, mechanical reliability, and biocompatibility has been excellent and no untoward effects have been observed. Long-term effectiveness of the ALVAS remains to be established in continuing experiments, with a 2 year period of clinical use as an ultimate goal.

Intraaortic balloon pumping women: effects of balloon size on survival

Between 1972 and 1978, 429 patients underwent intraaortic balloon pump (IABP) counterpulsation in our institution. Ninety-six were women (22.4). The overall mortality was 52.9% for men and 69.8% for women. During 1978, however, the mortality for women decreased to 57.1%, even though they comprised a larger percentage of patients (28.2%) than before. The major indication for IABP support in these women was ischemic myocardial dysfunction resulting in failure to wean from cardiopulmonary bypass (THI hemodynamic Classification C) despite volume expansion and pharmacologic support. Improved results were obtained with the use of larger intraaortic balloons and direct ascending aortic IABP insertion (which allowed use of larger, more effective 30 or 40 ml balloons), combined with delayed sternal closure.

Persistent atrial paralysis: Case report with light microscopy and ultrastructural analyses

Persistent atrial paralysis in a patient with complete heart block and mild mitral insufficiency is presented. Left atrial specimens obtained during implantation of a permanent cardiac pulse generator showed evidence of hypertrophy and fibrosis; subcellular degenerative changes ranged from near normal to irreversible, thus suggesting that atrial paralysis may be due to the replacement of normal atrial muscle with nonfunctional fibrous tissue.

Antibody levels detected by the fluorescent antibody technique in mice infected with Plasmodium vinckei and P. chabaudi

The malaria parasites of mice are convenient models for immunological studies. Plasmodium vinckei and P. chabaudi are similar parasites which behave differently in mice, the former invariably being fatal whereas the latter seldom kills the host. The experiments described in this paper were performed in order to compare the antibody levels in the Ig, IgM and IgG serum fractions in mice cured of P. vinckei infections and naturally recovered from P. chabaudi. The technique involved using specific labelled antimouse-Ig, -IgM and -IgG sera and had not previously been applied to malaria infections. The results showed that the patterns of antibody production were similar in cured and naturally recovered mice. IgG antibodies were involved from an early stage of the infection and IgM antibodies persisted throughout the period of experiment and even after challenge. These results are significant in that they indicate a pattern of immune response different from the classically accepted one and draw attention to the fact that even in highly immune animals considerable amounts of IgM may be present.