Effects of supplementing colostrum beyond the first day of life on growth and health parameters of preweaning Holstein heifers

The preweaning period for a dairy calf is characterized by high morbidity and mortality rates, leading to financial losses for producers. Identifying strategies to improve the health and welfare of calves while reducing antimicrobial use continues to be crucial to the success of the dairy industry. The objective of this study was to determine the effects of feeding colostrum replacer (CR) to dairy heifer calves beyond d 1 of life on growth, serum IgG, the incidence of diarrhea and bovine respiratory disease (BRD), and the risk of mortality in the preweaning period. At birth, Holstein heifer calves (n = 200; 50/treatment) weighing 40.7 ± 0.35 kg (mean ± SE) were fed 3.2 L of CR (205 g IgG/feeding) at 0 h and 12 h of life. Calves were then randomly assigned to 1 of 4 treatments: 450 g of milk replacer (MR) from d 2 to 14 (control, CON), 380 g of CR + 225 g of MR from d 2 to 3, then 450 g of MR from d 4 to 14 (transition, TRAN), 45 g of CR + 450 g of MR from d 2 to 14 (extended, EXT); or 380 g of CR + 225 g of MR from d 2 to 3, then 45 g of CR + 450 g of MR from d 4 to 14 (transition + extended, TRAN+EXT). Each treatment was reconstituted to 3 L and fed twice daily. All CR treatments were fed using bovine-derived CR containing 27% IgG. From d 15 to 41, all calves were fed 600 g of MR reconstituted to 4 L twice daily. Body weight was recorded at birth and every 7 d until study completion on d 49. Blood samples were taken daily until d 7 to evaluate serum IgG and then every 7 d until d 49. A health assessment was performed daily to evaluate calves for BRD and diarrhea. Data were analyzed using mixed linear regression, mixed logistic regression, and survival analysis models in SAS 9.4. Serum IgG concentrations were not affected by treatment for the study period. The EXT and TRAN+EXT groups had greater average daily gain (ADG) from d 7 to 14 (0.14 kg/d) and the TRAN group had greater ADG from d 14 to 21 (0.11 kg/d), compared with CON. There was no association of treatment with the odds or the duration of a diarrhea bout. However, provision of CR to the TRAN and EXT calves was associated with a reduced hazard of diarrhea compared with CON calves. Furthermore, TRAN and EXT calves have a lower hazard of mortality compared with CON calves, with TRAN and EXT calves had a 2.8- and 3.8-times lower hazard of mortality, respectively. Our findings suggest that the supplementation of CR to dairy calves positively affects ADG, and reduces the hazard of diarrhea and mortality during the preweaning period. Future research should look to further refine the supplementation strategy of CR to calves and explore the mechanism of action.

Effects of enriching IgG concentration in low- and medium-quality colostrum with colostrum replacer on IgG absorption in newborn Holstein calves

Ingestion and absorption of greater quantities of IgG are required to increase serum IgG levels in newborn calves. This could be achieved by adding colostrum replacer (CR) to maternal colostrum (MC). The objective of this study was to investigate whether low and high-quality MC can be enriched with bovine dried CR to achieve adequate serum IgG levels. Male Holstein calves (n = 80; 16/treatment) with birth body weights (BW) of 40 to 52 kg were randomly enrolled to be fed 3.8 L of the following combinations: 30 g/L IgG MC (C1), 60 g/L IgG MC (C2), 90 g/L IgG MC (C3), C1 enriched with 551 g of CR (60 g/L; 30-60CR), or C2 enriched with 620 g of CR (90 g/L: 60-90CR). A subset of 40 calves (8/treatment) had a jugular catheter placed and were fed colostrum containing acetaminophen at a dose of 150 mg/kg of metabolic body weight, to estimate abomasal emptying rate per hour (kABh). Baseline blood samples were taken (0 h), followed by sequential samples at 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 36, and 48 h relative to initial colostrum feeding. Results for all measurements are presented in the following order, unless otherwise stated: C1, C2, C3, 30-60CR, and 60-90CR. Serum IgG levels at 24 h were different among calves fed C1, C2, C3, 30-60CR, and 60-90CR: 11.8, 24.3, 35.7, 19.9, and 26.9 mg/mL ± 1.02 (mean ± SEM), respectively. Serum IgG at 24 h increased when enriching C1 to 30-60CR, but not from C2 to 60-90CR. Similarly, apparent efficiency of absorption (AEA) values for calves fed C1, C2, C3, 30-60CR, and 60-90CR were different: 42.4, 45.1, 43.2, 36.3, and 33.4% ± 1.93, respectively. Enriching C2 to 60-90CR reduced AEA, and enriching C1 to 30-60CR tended to decrease AEA. The kABh values for C1, C2, C3, 30-60CR, and 60-90CR were also different: 0.16, 0.13, 0.11, 0.09, and 0.09 ± 0.005, respectively. Enriching C1 to 30-60CR or C2 to 60-90CR reduced kABh. However, 30-60CR and 60-90CR have similar kABh compared with a reference colostrum meal (90 g/L IgG, C3). Even though kABh was reduced for 30-60CR, results indicate that C1 has the potential to be enriched and achieve acceptable serum IgG levels at 24 h without affecting AEA.

Effects of a low- or high-frequency colostrum feeding protocol on immunoglobulin G absorption in newborn calves

Calves might experience an upper limit of IgG absorption from colostrum ingestion at birth, but it is not clear whether the total IgG mass fed in the first meal or feeding frequencies can saturate the IgG transport mechanism and therefore limit IgG absorption. The objective of this study was to determine whether different colostrum replacer (CR) feeding frequencies affect serum IgG levels or apparent efficiency of absorption (AEA) in neonatal calves. Male Holstein calves (n = 40) were separated from their dams immediately after parturition and randomly assigned to receive CR [12% of birth body weight (BW)], following either (1) a low-frequency (LF; n = 20) or (2) a high-frequency (HF; n = 20) feeding protocol. Low-frequency calves received 2 CR meals (8% and 4% birth BW within 1 h after birth and 12 h after first CR feeding, respectively), whereas HF calves received 3 CR meals (4% of BW for each meal; within 1 h after birth, 6, and 12 h after first CR feeding). The CR powder fed had a dry matter IgG concentration of 30% and an IgG concentration of 70.5 g/L when reconstituted. All CR was fed via esophageal tube within 1 h after birth. Calves were bottle-fed pasteurized milk (5% birth BW) at 24, 36, and 48 h after the first CR feeding. Blood was collected before first CR feeding and at the following intervals post-CR feeding: every 2 h until 18 h; every 3 h from 18 to 30 h; and every 6 h from 30 to 48 h after the first CR feeding. Serum IgG values at 24 h did not differ between LF and HF (25.79 ± 0.93 and 25.66 ± 0.88 g/L, respectively). In the first meal, calves fed LF ingested a higher total IgG mass than HF (257.98 ± 4.16 g and 126.72 ± 4.05 g, respectively); however, AEA at 24 h did not differ for calves fed HF or LF (27.68 ± 1.16% and 27.63 ± 1.26%, respectively). The IgG area under the curve (AUC) at 24 h was greater for calves fed LF than HF (443.13 ± 15.17 and 379.59 ± 13.99 g of IgG/L × h, respectively). Additionally, AUC at 6 h, 12 h, and 48 h were greater for calves fed LF than HF. These results indicate that, although LF calves had a greater AUC, HF calves were still able to absorb IgG in the second and third meal, allowing HF calves to achieve serum IgG levels similar to those of LF calves at 24 h. In addition, the provision of 3 meals at 70.5 g/L of IgG within the first 12 h of life did not result in added benefits to serum IgG or AEA levels.

Invited review: The importance of colostrum in the newborn dairy calf

It is critical that bovine maternal colostrum is fed to newborn calves during their first hours of life. Colostrum is the secretion a cow produces after mammary involution that is rich in various nutrients. In addition to the nutritive value for newborn calves, immunoglobulins are of interest due to their role in developing the naïve immune system of calves at birth. The process by which a calf acquires immunity via absorption of immunoglobulins is defined as passive immunity. When calves consume an adequate amount of immunoglobulins, they are classified as having successful passive immunity (SPI). In contrast, if they are deprived of adequate colostrum, they are considered to have had a failure of transfer of passive immunity (FPI). Transfer of passive immunity is assessed by measuring serum IgG concentrations at 24 to 48 h of age. The major factors that influence whether a calf has SPI or FPI are colostrum IgG concentration, quantity fed, and age of calf at colostrum feeding. Monitoring apparent efficiency of immunoglobulin absorption in calves is often recommended to evaluate overall colostrum management practices. Serum IgG analyses can be determined with direct (radial immunodiffusion) or indirect (refractometry) methods and used to assess SPI or FPI prevalence.

ADSA Foundation Scholar Award: New frontiers in calf and heifer nutrition-From conception to puberty

Dairy calf nutrition is traditionally one of the most overlooked aspects of dairy management, despite its large effect on the efficiency and profitability of dairy operations. Unfortunately, among all animals on the dairy farm, calves suffer from the highest rates of morbidity and mortality. These challenges have catalyzed calf nutrition research over the past decade to mitigate high incidences of disease and death, and improve animal health, growth, welfare, and industry sustainability. However, major knowledge gaps remain in several crucial stages of development. The purpose of this review is to summarize the key concepts of nutritional physiology and programming from conception to puberty and their subsequent effects on development of the calf, and ultimately, future performance. During fetal development, developmental plasticity is highest. At this time, maternal energy and protein consumption can influence fetal development, likely playing a critical role in calf and heifer development and, importantly, future production. After birth, the calf's first meal of colostrum is crucial for the transfer of immunoglobulin to support calf health and survival. However, colostrum also contains numerous bioactive proteins, lipids, and carbohydrates that may play key roles in calf growth and health. Extending the delivery of these bioactive compounds to the calf through a gradual transition from colostrum to milk (i.e., extended colostrum or transition milk feeding) may confer benefits in the first days and weeks of life to prepare the calf for the preweaning period. Similarly, optimal nutrition during the preweaning period is vital. Preweaning calves are highly susceptible to health challenges, and improved calf growth and health can positively influence future milk production. Throughout the world, the majority of dairy calves rely on milk replacer to supply adequate nutrition. Recent research has started to re-evaluate traditional formulations of milk replacers, which can differ significantly in composition compared with whole milk. Transitioning from a milk-based diet to solid feed is critical in the development of mature ruminants. Delaying weaning age and providing long and gradual step-down protocols have become common to avoid production and health challenges. Yet, determining how to appropriately balance the amount of energy and protein supplied in both liquid and solid feeds based on preweaning milk allowances, and further acknowledging their interactions, shows great promise in improving growth and health during weaning. After weaning and during the onset of puberty, heifers are traditionally offered high-forage diets. However, recent work suggests that an early switch to a high-forage diet will depress intake and development during the time when solid feed efficiency is greatest. It has become increasingly clear that there are great opportunities to advance our knowledge of calf nutrition; yet, a more concentrated and rigorous approach to research that encompasses the long-term consequences of nutritional regimens at each stage of life is required to ensure the sustainability and efficiency of the global dairy industry.

Hot topic: Accuracy of refractometry as an indirect method to measure failed transfer of passive immunity in dairy calves fed colostrum replacer and maternal colostrum

Serum total protein (STP) refractometry is a widely used indicator of failed transfer of passive immunity (FTPI), defined as serum IgG concentrations of <10 mg/mL or STP levels <5.2 g/dL measured at 24 h of life. However, recent reports have demonstrated that refractometry could be inaccurate at estimating serum IgG concentrations and FTPI when calves are fed colostrum replacer (CR). The objective of this study was to evaluate the accuracy of STP measurements to estimate FTPI in calves fed CR compared with calves fed maternal colostrum. Blood was collected from dairy calves fed maternal colostrum (n = 927) or colostrum-derived CR (n = 1,258) and analyzed for STP and serum IgG. Serum total protein was measured with a digital refractometer, whereas radial immunodiffusion was used to determine IgG concentrations. Calves fed maternal colostrum had a mean STP of 5.80 ± 0.72 (standard deviation) g/dL and a mean IgG concentration of 22.81 ± 10.14 mg/mL, respectively, whereas calves fed CR had a mean STP and IgG concentration of 5.14 ± 0.50 g/dL and 12.78 ± 4.60 mg/mL, respectively. Rates of FTPI for calves fed maternal colostrum or CR were 4.2% and 27.26%, respectively. Calves were considered to have FTPI if their IgG postcolostrum feeding was <10 mg/mL. Logistic and linear regression analyses were performed to determine cutoff points and existent relationships between STP and IgG. Serum total protein and IgG for calves fed maternal colostrum were highly correlated. In contrast, STP and IgG for calves fed CR were lowly correlated. A receiver operator characteristic curve analysis demonstrated that an STP cutoff point that could predict FTPI when calves are fed CR would be 4.9 g/dL (sensitivity = 0.68; specificity = 0.75). This study suggests that current cutoff points used for STP inflates the number of calves estimated to have FTPI when they are fed CR.

Short communication: Variation in serum immunoglobulin G concentrations from birth to 112 days of age in Holstein calves fed a commercial colostrum replacer or maternal colostrum

Serum IgG concentrations in dairy calves change throughout their first weeks of life, peaking at 24 h and then steadily decreasing until calves begin to produce endogenous IgG. The objective of this study was to observe serum IgG dynamics from birth until 16 wk of life in calves fed either maternal colostrum (MC) or colostrum replacer (CR). A total of 44 Holstein calves were randomly assigned to 1 of the 4 colostrum treatments and followed throughout the study. Treatments consisted of feeding high-quality MC, low-quality MC supplemented with CR, or 1 of 2 distinct levels of IgG concentration from CR. Overall, the interaction between type of colostrum fed and sampling time was significant. Individual differences for this effect were found at d 1, 7, 14, 21, 28, and 98, while the other time points were not different.

Comparison of immunoglobulin G absorption in calves fed maternal colostrum, a commercial whey-based colostrum replacer, or supplemented maternal colostrum

Successful passive transfer of antibodies in neonatal calves can be achieved by feeding an adequate quantity and quality of maternal colostrum (MC) or colostrum replacer (CR). An alternative could be feeding low-quality maternal colostrum (LMC) with added IgG from a CR. The objective of this study was to determine if a commercial whey-based CR product containing low levels of casein (Premolac PLUS Bovine IgG; Zinpro Corporation, Eden Prairie, MN) fed to replace MC or supplement LMC could lead to adequate serum IgG levels and apparent efficiency of absorption (AEA) in neonatal dairy calves. Holstein calves (n = 20 per treatment) were separated from their dam after birth and randomly assigned to be fed 3.79 L of MC (106 g/L of IgG; 401 g of IgG fed), LMC (30 g/L IgG) supplemented with CR (41 g/L IgG; 154 g of IgG total fed; LMC-CR), or 1.3 L of 1 of 2 levels of CR (110 or 150 g of IgG fed; CR-110 or CR-150) within 1.5 h of birth. Colostrum was obtained from the first (MC) or second and third milkings (LMC) of cows from Pennsylvania State University dairy and pooled by source into large batches. Blood samples were taken from calves before colostrum feeding and 24 h after birth and were analyzed for serum total protein, total IgG, hematocrit, and Brix percentage. Calves fed MC had higher 24-h IgG values (means ± SEM) than calves fed LMC-CR (27.04 ± 1.07 vs. 22.33 ± 1.08 mg/mL, respectively). Feeding 150 g of IgG from CR led to higher 24-h serum IgG values than feeding 110 g of IgG (16.90 ± 1.09 vs. 12.79 ± 1.08 mg/mL). Serum IgG levels were different between the CR-fed calves and the calves fed LMC-CR and MC, but all had average values >10 mg/mL IgG. Calves fed LMC-CR had greater AEA than calves fed MC (54.58 ± 2.39 vs. 24.38 ± 2.36%, respectively). Among calves fed CR-110 or CR-150, AEA did not differ. Serum total protein and Brix percentage had strong correlations with actual IgG values across the entire study. We found no differences in average daily gain or health variables measured, and no differences in final hip width, withers height, or body weight for calves fed MC, LMC-CR, CR-150, or CR-110. These results indicate that CR can be fed successfully as an alternative to MC or as a supplement to colostrum with low IgG.

On the Interpretation of subtilisin Carlsberg Time-Resolved Fluorescence Anisotropy Decays: Modeling with Classical Simulations

In this work, we discuss the challenging time-resolved fluorescence anisotropy of subtilisin Carlsberg (SC), which contains a single Trp residue and is a model fluorescence system. Experimental decay rates and quenching data suggest that the fluorophore should be exposed to water, but the Trp is partially buried in a hydrophobic pocket in the crystallographic structure. In order to study this inconsistency, molecular dynamics simulations were performed to predict the anisotropy decay rates and emission wavelengths of the Trp. We confirmed the inconsistency of the crystallographic structure with the experimentally observed fluorescence data and performed free energy calculations to show that the buried Trp conformation is 2 orders of magnitude (∼3 kcal/mol) more stable than the solvent-exposed one. However, molecular dynamics simulations in which the Trp side chain was restricted to solvent-exposed conformations displayed a maximum Trp emission wavelength shifted toward lower energies and decay rates compatible with the experimentally probed rates. Therefore, if the solvent-exposed conformations are the most important emitters, the experimental anisotropy can be compatibilized with the crystallographic structure. The most likely explanation is that the fluorescence of the most probable conformation in solution, observed in the crystal, is quenched, and this is consistent with the low quantum yield of Trp113 of SC. Additionally, some experiments might have probed denatured or lysed SC structures. SC anisotropy provides an interesting target for the study of fluorescence anisotropy using simulations, which can be used to test and exemplify how modeling can aid the interpretation of experimental data in a system where structure and solution experiments appear to be inconsistent.

Parametric models to compute tryptophan fluorescence wavelengths from classical protein simulations

Fluorescence spectroscopy is an important method to study protein conformational dynamics and solvation structures. Tryptophan (Trp) residues are the most important and practical intrinsic probes for protein fluorescence due to the variability of their fluorescence wavelengths: Trp residues emit in wavelengths ranging from 308 to 360 nm depending on the local molecular environment. Fluorescence involves electronic transitions, thus its computational modeling is a challenging task. We show that it is possible to predict the wavelength of emission of a Trp residue from classical molecular dynamics simulations by computing the solvent-accessible surface area or the electrostatic interaction between the indole group and the rest of the system. Linear parametric models are obtained to predict the maximum emission wavelengths with standard errors of the order 5 nm. In a set of 19 proteins with emission wavelengths ranging from 308 to 352 nm, the best model predicts the maximum wavelength of emission with a standard error of 4.89 nm and a quadratic Pearson correlation coefficient of 0.81. These models can be used for the interpretation of fluorescence spectra of proteins with multiple Trp residues, or for which local Trp environmental variability exists and can be probed by classical molecular dynamics simulations. © 2018 Wiley Periodicals, Inc.

Ovarian Vein Diameter Cannot Be Used as an Indicator of Ovarian Venous Reflux

OBJECTIVES

Previous research into pelvic venous reflux has suggested that the size of the ovarian veins indicates the presence or absence of reflux. It is already known that vessel diameter is not an indicator of reflux in the great saphenous vein. However, to this day, physicians still use vein size to plan treatment of refluxing ovarian veins. The authors aimed to investigate whether or not vessel diameter can be used as an indicator of reflux in the ovarian veins.

METHODS

Nineteen female patients (mean 40.2 years, range 29-60) presenting to a specialist vein unit with leg varicose veins underwent duplex ultrasonography (DUS). All were found to have a significant pelvic contribution to their leg reflux on transvaginal duplex ultrasonography (TVS) and were referred to an interventional radiologist for treatment by transjugular coil embolization. During the procedure, the diameter of the ovarian veins was measured using digital subtraction venography.

RESULTS

Thirty-four ovarian veins were measured (17 right, 17 left) and of these 18 were found to be non-refluxing while 16 displayed reflux. The mean diameter of the non-refluxing veins was 7.2 mm (range 3-13 mm)and that of the refluxing veins was 8.5 mm (range 4-13 mm). This difference was found to be insignificant at a 95% confidence level (Student t test, p = .204).

CONCLUSIONS

There is no significant difference between the diameters of competent and refluxing ovarian veins and, as such, techniques that measure vein diameter may not be suitable for the diagnosis of venous reflux in the ovarian veins.

Transvaginal duplex ultrasonography appears to be the gold standard investigation for the haemodynamic evaluation of pelvic venous reflux in the ovarian and internal iliac veins in women

OBJECTIVES

To assess the suitability of transvaginal duplex ultrasonography to identify pathological reflux in the ovarian and internal iliac veins in women.

METHODS

A retrospective study of patients treated in 2011 and 2012 was performed in a specialised vein clinic. Diagnostic transvaginal duplex ultrasonography in women presenting with symptoms or signs of pelvic vein reflux were compared with the outcomes of treatment from pelvic vein embolisation. A repeat transvaginal duplex ultrasonography was performed 6 weeks later by a blinded observer and any residual reflux was identified.

RESULTS

Results from 100 sequential patients were analysed. Mean age 44.2 years (32-69) with mode average parity of 3 (0-5 deliveries). Pre-treatment, 289/400 veins were refluxing (ovarian - 29 right, 81 left; internal iliac - 93 right, 86 left). Coil embolisation was successful in 86/100 patients and failed partially in 14/100 - 5 due to failure to cannulate the target vein. One false-positive diagnosis was made.

CONCLUSION

Currently there is no accepted gold standard for pelvic vein incompetence. Comparing transvaginal duplex ultrasonography with the outcome from selectively treating the veins identified as having pathological reflux with coil embolisation, there were no false-negative diagnoses and only one false-positive. This study suggests that transvaginal duplex ultrasonography could be the gold standard in assessing pelvic vein reflux.

The major genetic determinants of HIV-1 control affect HLA class I peptide presentation

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection.

Radiological insertion and management of peritoneovenous shunt

The purpose of the study was to report our experience of the management of complications following the insertion of a peritoneovenous shunt for intractable malignant ascites. From June 1999 to January 2006, 26 patients underwent insertion of a peritoneovenous shunt for ascites by interventional radiologists. We have used ultrasound and shuntography to assist in the diagnosis of the cause of shunt blockage. Successful techniques for the restoration of the shunt function include port- pumping, stripping of any fibrin sheath, and revision of either the venous or peritoneal catheter. The procedure was initially successful in all patients with continued patency until death in 17. A further four patients are still alive with a functioning shunt. There was one rapid postprocedure death resulting from pulmonary edema. Two patients developed pneumothorax, managed successfully with either a chest drain or aspiration. Shunt dysfunction occurred eight times in seven patients. There were five successful revisions in four patients. Overall, shunt patency has been maintained in 80.1% of patients. Shunt dysfunction is seen in a significant number of patients, but successful revision of the shunt can be achieved in the majority.

Candida inferior vena cava filter infection and septic thrombophlebitis

Candida infection following central venous catheterization (CVC) is a well known complication, most common infection being that caused by Candida albicans. Less common is infection with Candida glabrata. Candida septic thrombophlebitis of the central veins is an uncommon complication after CVC. We report the first case of inferior vena cava filter infection with C. glabrata following septic thrombophlebitis of the femoral veins and discuss management of this rare complication.

Fast-Track Management of Malignant Superior Vena Cava Syndrome

We report our experience with a combined approach of endovascular biopsy followed by immediate stenting in the management of superior vena cava (SVC) syndrome secondary to obstructing mediastinal masses. A diagnosis of malignancy was obtained in six of eight (75%) biopsies and symptomatic relief was accomplished in all patients. We have found this to be a rapid, safe and effective management strategy that we now consider for all patients presenting with de novo SVC syndrome.

A review of alternative approaches in the management of iatrogenic femoral pseudoaneurysms

The management of iatrogenic pseudoaneurysms (IPAs) demands close co-operation between radiologist, vascular surgeon and plastic surgeon. Ideally, each patient should be reviewed employing a team approach. Many IPAs require only observation; those with a volume greater than 6 cm3 will require treatment as spontaneous thrombosis is uncommon. Radiological treatment options include ultrasound guided compression repair (UGCR), embolisation, and covered stenting. Occasionally, these are unsuccessful or contra-indicated, and the vascular surgical approach is discussed in detail. Finally, the role of the plastic surgeon in dealing with skin ischaemia is detailed.

Trans-acting factors required for inclusion of regulated exons in the Ultrabithorax mRNAs of Drosophila melanogaster

Alternatively spliced Ultrabithorax mRNAs differ by the presence of internal exons mI and mII. Two approaches were used to identify trans-acting factors required for inclusion of these cassette exons. First, mutations in a set of genes implicated in the control of other alternative splicing decisions were tested for dominant effects on the Ubx alternative splicing pattern. To identify additional genes involved in regulation of Ubx splicing, a large collection of deficiencies was tested first for dominant enhancement of the haploinsufficient Ubx haltere phenotype and second for effects on the splicing pattern. Inclusion of the cassette exons in Ubx mRNAs was reduced strongly in heterozygotes for hypomorphic alleles of hrp48, which encodes a member of the hnRNP A/B family and is implicated in control of P-element splicing. Significant reductions of mI and mII inclusion were also observed in heterozygotes for loss-of-function alleles of virilizer, fl(2)d, and crooked neck. The products of virilizer and fl(2)d are also required for Sxl autoregulation at the level of splicing; crooked neck encodes a protein with structural similarities to yeast-splicing factors Prp39p and Prp42p. Deletion of at least five other loci caused significant reductions in the inclusion of mI and/or mII. Possible roles of identified factors are discussed in the context of the resplicing strategy for generation of alternative Ubx mRNAs.

Alternative splicing of pre-mRNA: developmental consequences and mechanisms of regulation

Alternative splicing of pre-mRNAs is a powerful and versatile regulatory mechanism that can effect quantitative control of gene expression and functional diversification of proteins. It contributes to major developmental decisions and also to fine tuning of gene function. Genetic and biochemical approaches have identified cis-acting regulatory elements and trans-acting factors that control alternative splicing of specific pre-mRNAs. Both approaches are contributing to an understanding of their mode of action. Some alternative splicing decisions are controlled by specific factors whose expression is highly restricted during development, but others may be controlled by more modest variations in the levels of general factors acting cooperatively or antagonistically. Certain factors play active roles in both constitutive splicing and regulation of alternative splicing. Cooperative and antagonistic effects integrated at regulatory elements are likely to be important for specificity and for finely tuned differences in cell-type-specific alternative splicing patterns.

The endovascular management of blue finger syndrome

OBJECTIVES

To review our experience of the endovascular management of upper limb embolisation secondary to an ipsilateral proximal arterial lesion.

DESIGN

A retrospective study.

MATERIALS AND METHODS

Over 3 years, 17 patients presented with blue fingers secondary to an ipsilateral proximal vascular lesion. These have been managed using transluminal angioplasty (14) and arterial stenting (five), combined with embolectomy (two) and anticoagulation (three)/anti-platelet therapy (14).

RESULTS

All the patients were treated successfully. There have been no further symptomatic embolic episodes originating from any of the treated lesions, and no surgical amputations. Complications were associated with the use of brachial arteriotomy for vascular access.

CONCLUSIONS

Endovascular techniques are safe and effective in the management of upper limb embolic phenomena associated with an ipsilateral proximal focal vascular lesion.

Generation of alternative Ultrabithorax isoforms and stepwise removal of a large intron by resplicing at exon-exon junctions

Little is known about mechanisms that regulate and ensure accurate processing of complex transcription units with long introns. We investigate this in the Ultrabithorax gene of Drosophila. A consensus 5' splice site is regenerated at the junction between the first exon and a small internal exon (mI); this splice site is used in a developmentally regulated manner to remove mI during subsequent processing of the downstream intron. Conserved elements within mI and an interaction with exon mII modulate use of the regenerated splice site. Structural similarities predict the same process for mII. This resplicing mechanism avoids competition between distant splice sites for control of exon inclusion and allows removal of a 74 kb intron as a series of smaller fragments.

CD-tagging: a new approach to gene and protein discovery and analysis

We describe a new method for gene discovery and analysis, CD-tagging, that puts specific molecular tags on a gene, its transcript and its protein product. The method has been successfully tested in two organisms, the haploid unicellular alga Chlamydomonas reinhardtii and the metazoan Drosophila melanogaster. The method utilizes a specially designed DNA molecule, the CD-cassette, that contains splice acceptor and donor sites surrounding a short open reading frame. Insertion of the CD-cassette into an intron in a target gene introduces a new exon, represented by the open reading frame of the CD-cassette, surrounded by two functional hybrid introns. As a result (i) the gene is tagged by a specific nucleotide sequence, (ii) the mRNA is tagged by a specific nucleotide sequence and (iii) the protein is tagged by a specific peptide sequence. Because these tags are unique, specific nucleotide or antibody probes can be used to obtain and/or analyze the gene, transcript or protein. As a gene discovery technology, CD-tagging has two unique advantages: 1) Genes can be identified through a primary screen at the protein level, and so the very process by which a gene is identified provides specific empirical information about its biological function. 2) The cassette arms, which are spliced out of the transcript of the target gene, are available to carry a wide variety of DNA sequences, such as genes encoding drug resistance that can be used to select for the presence of the CD-cassette in the genome.

Technical note: radiological insertion of an implantable drug delivery system

A fully implantable drug delivery system has been shown to overcome many of the problems of long-term venous access. Traditionally these have required surgical implantation but we describe a simple, cost-effective and successful technique for the percutaneous insertion of an implantable vascular device (Vascuport, Ohmeda) in the angiography suite under local anaesthesia. It was successful in all 19 patients in whom it was attempted, with only one minor complication. We recommend that the procedure should be performed in X-ray departments using screening and conventional guidewire techniques.

Case report: Therapeutic bronchial artery embolization in a case of Takayasu's arteritis

The pulmonary arteries are frequently involved in Takayasu's arteritis with a reported incidence of 41-100% in affected individuals. Patients are usually asymptomatic, however, often despite extensive pulmonary involvement. We describe a patient with Takayasu's arteritis who presented with haemoptysis caused by bronchial artery hypertrophy secondary to occlusive pulmonary arterial disease, who was treated by bronchial artery embolization. This is, to our knowledge, the first reported case of haemoptysis secondary to Takayasu's arteritis successfully treated by embolization.

Immunochemical dissection of the Ultrabithorax homeoprotein family in Drosophila melanogaster

The homeotic gene Ultrabithorax (Ubx) specifies metameric identities in multiple tissues of the thorax and abdomen in Drosophila melanogaster. Alternatively spliced Ultrabithorax mRNAs encode five protein isoforms that differ in internal sequences immediately adjacent to a homeodomain DNA-binding motif. Each of these proteins is phosphorylated in vivo at multiple serine and threonine residues. An extensive panel of monoclonal antibodies was raised against the Ultrabithorax proteins, including antibodies specific for individual isoforms and antibodies that discriminated between different phosphorylation states. Characterization of these antibodies provided insights into shared and isoform-specific features of Ultrabithorax protein structure that may be functionally important. Immunohistochemical staining experiments demonstrated that each isoform is expressed in a different stage- and tissue-specific pattern and suggested that Ultrabithorax protein phosphorylation is also developmentally regulated. These results support the hypothesis that alternative splicing and phosphorylation modulate developmentally specific functions of the Ubx gene.

Phase I clinical and pharmacokinetic study of trimetrexate using a daily x5 schedule

Trimetrexate (TMQ; NSC 352122) is a potent inhibitor of dihydrofolate reductase with good activity against murine i.p.-implanted B16 melanoma and colon 26 tumors. Preclinical antineoplastic activity, demonstrated schedule dependency, and data suggesting effectiveness against methotrexate-resistant cells prompted a Phase I clinical and pharmacokinetic study of trimetrexate using an i.v. daily x5 schedule. Forty-three good performance status patients were treated with 12 dose levels using daily doses varying from 0.5 to 15 mg/m2/d. Plasma and urine samples were obtained for pharmacokinetic analysis using a high-performance liquid chromatographic method. Myelosuppression was dose limiting and 15 mg/m2/d x5 was the maximum tolerated dose. White blood cell (WBC) and platelet toxicity were noted at doses of 1.6 mg/m2 and above. Median WBC and platelet nadirs occurred on approximately Days 11-12 with recovery by Days 15-18. Nonhematological toxicity included mucositis, nausea and vomiting, stomatitis, diarrhea, and rash. Evidence for antitumor activity was seen in seven patients. Trimetrexate elimination from plasma could be represented as either a bi- or triexponential process. Terminal elimination half-lives were in the range of 5-14 h in patients represented by a triexponential model. Approximately 10-20% of the dose administered was excreted in urine over a 24-h period. The recommended starting dose for patients in Phase II trials using the d x5 i.v. schedule is 8.0 mg/m2/d repeated every 21 days. Dose escalations may be possible depending on the extent of prior therapy and individual tolerance of the drug.

Studies on the mechanism of the acute and carcinogenic effects of N-nitrosodimethylamine on mink liver

Outbreaks of liver necrosis and liver hemangiosarcoma were detected in a mink breeding colony in Argentina. Analysis of the Minks' food revealed the presence of 2.6 ppm dimethylnitrosamine (NDMA) in it, apparently as a result of the addition of nitrite as preservative. Previous studies gave evidence of the particular susceptibility of minks to NDMA and other hepatic insults. We have determined several biochemical parameters known to correlate with NDMA hepatotoxic effects and compared them with those in rat liver. NDMA administration to both species resulted in the formation of reactive metabolites able to interact with liver DNA to give N7-methylguanine and O6-methylguanine adducts. Biotransformation of NDMA by liver slices to CO2 was significantly lower in the mink than in the rat, whereas the covalent binding (CB) to nucleic acids was slightly lower than in in the rat. Aminopyrine N-demethylase activity was also significantly less in mink than in rat liver. The CB of NDMA reactive metabolites to microsomal proteins was not significantly lower in mink as compared to the rat, and the same holds true for the biotransformation of NDMA to formaldehyde by microsomal preparations. Results suggest that the high susceptibility of minks to NDMA might be partially due to a decreased ability to detoxicate NDMA but also to a higher intrinsic susceptibility of their liver cells to a given chemical insult.