Classifying batted ball outcomes from Division I collegiate baseball players

Modern technology challenges anecdotal beliefs on baseball performance. The study's purpose examines these beliefs by classifying batted ball outcomes. Three categories of independent variables (anthropometry, in-game situation, technique-based), from 1,922 batted ball outcomes produced by 230 players, were used to classify the likelihood of hits during 2021 college baseball games. Anthropometry included player's heights and weights. In-game situation entailed batter side, same side, ahead count, and pitch type. Technique-based variables measured by TrackMan radar included exit speed (ExSp), launch angle (LA), batted ball distance (BBD), and hang time (HT). Binary logistic regression analysis was performed with batted ball outcome as the dependent variable. Independent variables provided a good fit (χ2 (10) = 522.358, p < 0.01) and correctly classified nearly three-fourths of outcomes. Height (β = 0.030, p < 0.05), ExSp (β = 0.023, p < 0.05), LA (β = 0.028, p < 0.01), and BBD (β = 0.067, p < 0.01) each had significant positive associations, yet HT (β = -1.661, p < 0.01) had a significant negative association, with batted ball outcomes. TrackMan provided four significant independent variables. Anthropometry's contribution to batting outcome was modest, while in-game situation's impact was non-significant; results contradict anecdotal beliefs of their importance.

The impact of three learning methods on dental students' satisfaction and knowledge acquisition

OBJECTIVES

Health professionals' education presents unique challenges including clinical application of knowledge and interprofessional collaboration. Additionally, institutions suffer from faculty shortages while class sizes increase. Therefore, educators seek innovative andragogical techniques utilizing minimal resources. Several active learning methods have been introduced as a solution. The aim of this study is to assess the impact of lecture (LBL), case (CBL), and team (TBL) based learning on the students' satisfaction and knowledge attainment.

METHODS

A total of 134 sophomore dental students are taught pediatric dentistry course using LBL, CBL, and TBL techniques. At the end of the course, students are invited to participate in a satisfaction survey. Statistical analysis is conducted using a two-sided chi-square goodness of fit test. Students' comments are used for qualitative analysis. Final exam analysis is administered via Examsoft software.

RESULTS

A total of 98% of the students participated in the survey out of which 83% met the inclusion criteria (N = 110). Students chose LBL as the method that helped them learn in a comprehensive way, provided the most comfortable environment, and presented the overall highest satisfaction with statistically significant difference (p value = 0.001). LBL questions scored the highest point biserial and discrimination index. The percentage of correct answers and difficulty level was highest for TBL.

CONCLUSION

Students preferred LBL over the other learning methods. Final exam psychometrics showed favorable results for LBL and TBL. Students could potentially benefit from combining both techniques. However, more research is needed to assess the effectiveness of various teaching methods on the short- and long-term learning outcomes.

Pitch release speed predictors for division I collegiate baseball players

BACKGROUND: Analytics, to quantify baseball pitch metrics, take on many forms and are unlike earlier methods to assess performance. OBJECTIVE: Quantify associations of flight kinematic and anthropometric variables on pitch release speed. METHODS: Male college-age pitchers (n= 182) from 2021 Division I games provided data. A 3D radar system collected data. Fixed effects regression OLS models analyzed data for sliders, changeups, curveballs, and fastballs. RESULTS: Spin rate (r= 0.017–0.514, p< 0.05) and vertical break (r= 0.374–0.703, p< 0.05) were positively associated with pitch release speed per pitch type. Release height (r=-0.286–0.051, p<-0.05) and pitch extension (r=-0.176–0.43, p< 0.05) were negatively associated with pitch release speed per pitch type except sliders. Spin axis had a negative association with pitch release speed for fastballs (r=-0.235, p< 0.05) and sliders (r=-0.311, p< 0.05), and a positive association (r= 0.029, p< 0.05) with curveball pitch release speed. Weight only related to pitch release speed for fastballs (r=-0.315, p< 0.05). Height did not impact pitch release speed. CONCLUSIONS: Results refute long-held beliefs of anthropometry’s influence on performance and instead reveal flight kinematics’ impact on baseball pitch release speed.

Measuring home environments across cultures: Invariance of the HOME scale across eight international sites from the MAL-ED study

The home environment provides the context for much of a child's early development. Examples of important aspects of the home environment include safety, cleanliness, and opportunities for cognitive stimulation. This study sought to examine the psychometric properties of an adapted form of the Home Observation for the Measurement of the Environment (HOME; Caldwell & Bradley, 1984, 2003) across the eight international sites of the MAL-ED project (Dhaka, Bangladesh; Vellore, India; Bhakatapur, Nepal; Naushahro Feroze, Pakistan; Fortaleza, Brazil; Loreto, Peru; Venda, South Africa; Haydom, Tanzania), to identify a factor structure that fit the data at all sites, and to derive a subset of items that could be used to examine home environmental characteristics across sites. A three-factor structure (i.e., Emotional and Verbal Responsivity; Clean and Safe Environment; Child Cleanliness) was identified, and partial measurement equivalence/invariance across sites was supported. Overall, these findings lend support for the use of portions of this abbreviated and adapted version of the HOME for use among heterogeneous, cross-cultural groups in low- and middle-income nations.

Validation of the talar-second metatarsal angle as a standard measurement for radiographic evaluation

BACKGROUND

Radiographs provide valuable information for assessing osseous foot deformities and aid in accurate diagnosis. The radiographic angular measurements can be used to establish a relationship between the forefoot and the hindfoot that will present valuable information about normal versus pathologic alignment of the foot. The talar-first metatarsal (T1M) angle is frequently used as one of these angles in this capacity; however, there are limitations to the anteroposterior T1M angle. We present a more consistent, reproducible, and accurate measurement for determining foot abnormalities in the transverse plane using the T2M angle instead of the T1M angle.

METHODS

Seventy feet in 35 participants (12 men and 23 women) were considered for this study. Individuals were selected on the basis of the established inclusion and exclusion criteria. Anteroposterior radiographs were taken in the angle and base of gait, the neutral calcaneal stance position (NCSP), and the resting calcaneal stance position (RCSP). Three observers measured these angles using three different methods.

RESULTS

The mean ± SD T2M angle was 2.95° ± 7.16° in NCSP and 18.61° ± 7.21° in RCSP. No significant differences were found among the measurements made by the three observers using slightly varying procedures in NCSP and RCSP (P > .05). The intraclass correlation coefficients among the measurements were 0.905 in NCSP and 0.937 in RCSP. Bland-Altman plots showed very good agreement between the measurements made by the three observers.

CONCLUSIONS

The anteroposterior T2M angle gives a consistent and reproducible measurement that provides accurate information about foot alignment.

The rotor in the membrane of the ATP synthase and relatives

In recent years, structural information on the F(1) sector of the ATP synthase has provided an insight into the molecular mechanism of ATP catalysis. The structure strongly supports the proposal that the ATP synthase works as a rotary molecular motor. Insights into the membrane domain have just started to emerge but more detailed structural information is needed if the molecular mechanism of proton translocation coupled to ATP synthesis is to be understood. This review will focus mainly on the ion translocating rotor in the membrane domain of the F-type ATPase, and the related vacuolar and archaeal relatives.

Introduction of a carboxyl group in the first transmembrane helix of Escherichia coli F1Fo ATPase subunit c and cytoplasmic pH regulation

The multicopy subunit c of the H(+)-transporting F1Fo ATP synthase of Escherichia coli folds across the membrane as a hairpin of two hydrophobic alpha helices. The subunits interact in a front-to-back fashion, forming an oligomeric ring with helix 1 packing in the interior and helix 2 at the periphery. A conserved carboxyl, Asp(61) in E. coli, centered in the second transmembrane helix is essential for H+ transport. A second carboxylic acid in the first transmembrane helix is found at a position equivalent to Ile28 in several bacteria, some the cause of serious infectious disease. This side chain has been predicted to pack proximal to the essential carboxyl in helix 2. It appears that in some of these bacteria the primary function of the enzyme is H+ pumping for cytoplasmic pH regulation. In this study, Ile28 was changed to Asp and Glu. Both mutants were functional. However, unlike the wild type, the mutants showed pH-dependent ATPase-coupled H+ pumping and passive H+ transport through Fo. The results indicate that the presence of a second carboxylate enables regulation of enzyme function in response to cytoplasmic pH and that the ion binding pocket is aqueous accessible. The presence of a single carboxyl at position 28, in mutants I28D/D61G and I28E/D61G, did not support growth on a succinate carbon source. However, I28E/D61G was functional in ATPase-coupled H+ transport. This result indicates that the side chain at position 28 is part of the ion binding pocket.

Insights into the rotary catalytic mechanism of F0F1 ATP synthase from the cross-linking of subunits b and c in the Escherichia coli enzyme

The transmembrane sector of the F(0)F(1) rotary ATP synthase is proposed to organize with an oligomeric ring of c subunits, which function as a rotor, interacting with two b subunits at the periphery of the ring, the b subunits functioning as a stator. In this study, cysteines were introduced into the C-terminal region of subunit c and the N-terminal region of subunit b. Cys of N2C subunit b was cross-linked with Cys at positions 74, 75, and 78 of subunit c. In each case, a maximum of 50% of the b subunit could be cross-linked to subunit c, which suggests that either only one of the two b subunits lie adjacent to the c-ring or that both b subunits interact with a single subunit c. The results support a topological arrangement of these subunits, in which the respective N- and C-terminal ends of subunits b and c extend to the periplasmic surface of the membrane and cAsp-61 lies at the center of the membrane. The cross-linking of Cys between bN2C and cV78C was shown to inhibit ATP-driven proton pumping, as would be predicted from a rotary model for ATP synthase function, but unexpectedly, cross-linking did not lead to inhibition of ATPase activity. ATP hydrolysis and proton pumping are therefore uncoupled in the cross-linked enzyme. The c subunit lying adjacent to subunit b was shown to be mobile and to exchange with c subunits that initially occupied non-neighboring positions. The movement or exchange of subunits at the position adjacent to subunit b was blocked by dicyclohexylcarbodiimide. These experiments provide a biochemical verification that the oligomeric c-ring can move with respect to the b-stator and provide further support for a rotary catalytic mechanism in the ATP synthase.

Structural interpretations of F(0) rotary function in the Escherichia coli F(1)F(0) ATP synthase

F(1)F(0) ATP synthases are known to synthesize ATP by rotary catalysis in the F(1) sector of the enzyme. Proton translocation through the F(0) membrane sector is now proposed to drive rotation of an oligomer of c subunits, which in turn drives rotation of subunit gamma in F(1). The primary emphasis of this review will be on recent work from our laboratory on the structural organization of F(0), which proves to be consistent with the concept of a c(12) oligomeric rotor. From the NMR structure of subunit c and cross-linking studies, we can now suggest a detailed model for the organization of the c(12) oligomer in F(0) and some of the transmembrane interactions with subunits a and b. The structural model indicates that the H(+)-carrying carboxyl of subunit c is located between subunits of the c(12) oligomer and that two c subunits pack in a front-to-back manner to form the proton (cation) binding site. The proton carrying Asp61 side chain is occluded between subunits and access to it, for protonation and deprotonation via alternate entrance and exit half-channels, requires a swiveled opening of the packed c subunits and stepwise association with different transmembrane helices of subunit a. We suggest how some of the structural information can be incorporated into models of rotary movement of the c(12) oligomer during coupled synthesis of ATP in the F(1) portion of the molecule.

Mutations in single hairpin units of genetically fused subunit c provide support for a rotary catalytic mechanism in F(0)F(1) ATP synthase

Previously, we generated genetically fused dimers and trimers of subunit c of the Escherichia coli ATP synthase based upon the precedent of naturally occurring dimers in V-type H(+)-transporting ATPases. The c(2) and c(3) oligomers have proven useful in testing hypothesis regarding the mechanism of energy coupling. In the first part of this paper, the uncoupling Q42E substitution has been introduced into the second loop of the c(2) dimer or the third loop of the c(3) trimer. Both mutant proteins proved to be as functional as the wild type c(2) dimer or wild type c(3) trimer. The results argue against an obligatory movement of the epsilon subunit between loops of monomeric subunit c in the c(12) oligomer during rotary catalysis. Rather, the results support the hypothesis that the c-epsilon connection remains fixed as the c-oligomer rotates. In the second section of this paper, we report on the effect of substitution of the proton translocating Asp(61) in every second helical hairpin of the c(2) dimer, or in every third hairpin of the c(3) trimer. Based upon the precedent of V-type ATPases, where the c(2) dimer occurs naturally with a single proton translocating carboxyl in every second hairpin, these modified versions of the E. coli c(2) and c(3) fused proteins were predicted to have a functional H(+)-transporting ATPase activity, with a reduced H(+)/ATP stoichiometry, but to be inactive as ATP synthases. A variety of Asp(61)-substituted proteins proved to lack either activity indicating that the switch in function in V-type ATPases is a consequence of more than a single substitution.

Structure of the subunit c oligomer in the F1Fo ATP synthase: model derived from solution structure of the monomer and cross-linking in the native enzyme

The structure of the subunit c oligomer of the H+-transporting ATP synthase of Escherichia coli has been modeled by molecular dynamics and energy minimization calculations from the solution structure of monomeric subunit c and 21 intersubunit distance constraints derived from cross-linking of subunits. Subunit c folds in a hairpin-like structure with two transmembrane helices. In the c12 oligomer model, the subunits pack to form a compact hollow cylinder with an outer diameter of 55-60 A and an inner space with a minimal diameter of 11-12 A. Phospholipids are presumed to pack in the inner space in the native membrane. The transmembrane helices pack in two concentric rings with helix 1 inside and helix 2 outside. The calculations strongly favor this structure versus a model with helix 2 inside and helix 1 outside. Asp-61, the H+-transporting residue, packs toward the center of the four transmembrane helices of two interacting subunits. From this position at the front face of one subunit, the Asp-61 carboxylate lies proximal to side chains of Ala-24, Ile-28, and Ala-62, projecting from the back face of a second subunit. These interactions were predicted from previous mutational analyses. The packing supports the suggestion that a c-c dimer is the functional unit. The positioning of the Asp-61 carboxyl in the center of the interacting transmembrane helices, rather than at the periphery of the cylinder, has important implications regarding possible mechanisms of H+-transport-driven rotation of the c oligomer during ATP synthesis.

Telematics in the neonatal ICU and beyond: improving care, communication and information sharing

In October of 1998, the Beth Israel-Deaconess was awarded one of 19 contracts from the National Library of Medicine (NLM) to develop, implement and test a telemedicine application to support the care of Very Low Birth Weight Infants. This project is the only one to focus on the care of newborns. We believe that this project will provide a new national approach to managing the care of high-risk newborns by leveraging evolving communication technology.

Structure of the membrane domain of subunit b of the Escherichia coli F0F1 ATP synthase

The structure of the N-terminal transmembrane domain (residues 1-34) of subunit b of the Escherichia coli F0F1-ATP synthase has been solved by two-dimensional 1H NMR in a membrane mimetic solvent mixture of chloroform/methanol/H2O (4:4:1). Residues 4-22 form an alpha-helix, which is likely to span the hydrophobic domain of the lipid bilayer to anchor the largely hydrophilic subunit b in the membrane. The helical structure is interrupted by a rigid bend in the region of residues 23-26 with alpha-helical structure resuming at Pro-27 at an angle offset by 20 degrees from the transmembrane helix. In native subunit b, the hinge region and C-terminal alpha-helical segment would connect the transmembrane helix to the cytoplasmic domain. The transmembrane domains of the two subunit b in F0 were shown to be close to each other by cross-linking experiments in which single Cys were substituted for residues 2-21 of the native subunit and b-b dimer formation tested after oxidation with Cu(II)(phenanthroline)2. Cys residues that formed disulfide cross-links were found with a periodicity indicative of one face of an alpha-helix, over the span of residues 2-18, where Cys at positions 2, 6, and 10 formed dimers in highest yield. A model for the dimer is presented based upon the NMR structure and distance constraints from the cross-linking data. The transmembrane alpha-helices are positioned at a 23 degrees angle to each other with the side chains of Thr-6, Gln-10, Phe-14, and Phe-17 at the interface between subunits. The change in direction of helical packing at the hinge region may be important in the functional interaction of the cytoplasmic domains.

Genetic fusions of subunit c in the F0 sector of H+-transporting ATP synthase. Functional dimers and trimers and determination of stoichiometry by cross-linking analysis

The multicopy c subunit of the H+-transporting ATP synthase of Escherichia coli folds through the transmembrane F0 sector as a hairpin of two hydrophobic alpha-helices with the proton-translocating aspartyl-61 side chain centered in the second transmembrane helix. The number of subunits c in the F0 complex, which is thought to determine the H+-pumping/ATP stoichiometry, was previously not determined with exactness but thought to range from 9-12. The studies described here indicate that the exact number is 12. Based upon the precedent of the subunit c in vacuolar-type ATPases, which are composed of four transmembrane helices and seem to have evolved by gene duplication of an F0-type progenitor gene, we constructed genetically fused dimers and trimers of E. coli subunit c. Both the dimeric and trimeric forms proved to be functional. These results indicate that the total number of subunit c in F0 should be a multiple of 2 and 3. Based upon a previous study in which the oligomeric organization of c subunits in F0 was determined by cross-linking of Cys-substituted subunits (Jones, P. C. , Jiang, W., and Fillingame, R. H. (1998) J. Biol. Chem. 273, 17178-17185), we introduced Cys into the first and last transmembrane helices of subunit c monomers, dimers, and trimers and attempted to generate cross-linked products by oxidation with Cu(II)-(1,10-phenanthroline)2. Double Cys substitutions at two sets of positions gave rise to extensive cross-linked multimers. Multimers of the monomer that extended up to the position of c12 were correlated and calibrated with distinct cross-linked species of the appropriate doubly Cys-substituted dimers (i.e. c2, c4, . c12) and doubly Cys-substituted trimers (i.e. c3, c6, c9, c12). The results show that there are 12 copies of subunit c per F0 in E. coli, the exact number having both mechanistic and structural significance.

Arrangement of the multicopy H+-translocating subunit c in the membrane sector of the Escherichia coli F1F0 ATP synthase

The multicopy subunit c of the H+-transporting F1F0 ATP synthase of Escherichia coli is thought to fold across the membrane as a hairpin of two hydrophobic alpha-helices. The conserved Asp61, centered in the second transmembrane helix, is essential for H+ transport. In this study, we have made sequential Cys substitutions across both transmembrane helices and used disulfide cross-link formation to determine the oligomeric arrangement of the c subunits. Cross-link formation between single Cys substitutions in helix 1 provided initial limitations on how the subunits could be arranged. Double Cys substitutions at positions 14/16, 16/18, and 21/23 in helix 1 and 70/72 in helix 2 led to the formation of cross-linked multimers upon oxidation. Double Cys substitutions in helix 1 and helix 2, at residues 14/72, 21/65, and 20/66, respectively, also formed cross-linked multimers. These results indicate that at least 10 and probably 12 subunits c interact in a front-to-back fashion to form a ring-like arrangement in F0. Helix 1 packs at the interior and helix 2 at the periphery of the ring. The model indicates that the Asp61 carboxylate is centered between the helical faces of adjacent subunit c at the center of a four-helix bundle.

Subunit organization and structure in the F0 sector of Escherichia coli F1F0 ATP synthase

In this review, we summarize recent work from our laboratory which establishes the topology and nearest neighbor organization of subunits in the F0 sector of the H+ transporting ATP synthase of Escherichia coli. The E. coli F0 sector is composed of three subunits in an a1b2c12 stoichiometric ratio. Crosslinking experiments with genetically introduced Cys establish a ring-like organization of the 12 c subunits with subunits a and b lying to the outside of the ring. The results are interpreted using an atomic resolution structural model of monomeric subunit c in a chloroform-methanol-water (4:4:1, v/v/v) solution, derived by heteronuclear NMR (M.E. Girvin, F. Abildgaard, V. Rastogi, J. Markley, R.H. Fillingame, in press). The crosslinking results validate many predictions of the structural model and confirm a front-to-back-type packing of two subunit c into a functional dimer, as was first predicted from genetic studies. Aspartyl-61, the proton translocating residue, lies at the center of the four transmembrane helices of the functional dimer, rather than at the periphery of the subunit c ring. Subunit a is shown to fold with five transmembrane helices, and a functionally important interaction of transmembrane helix-4 with transmembrane helix-2 of subunit c is established. The single transmembrane helices of the two subunit b dimerize in the membrane. The structure of the transmembrane segment of subunit b is predicted from the NMR structure of the monomeric peptide.

Electronic communication and collaboration in a health care practice

Using cognitive evaluation techniques, this study examines the effects of an electronic patient record and electronic mail on the interactions of health care providers. We find that the least structured communication methods are also the most heavily used: face-to-face, telephone, and electronic mail. Positive benefits of electronically-mediated interactions include improving communication, collaboration, and access to information to support decision-making. Negative factors include the potential for overloading clinicians with unwanted or unnecessary communications.

Nationwide telecare for diabetics: a pilot implementation of the HOLON architecture

This paper presents results from a demonstration project of nationwide exchange of health data for the home care of diabetic patients. A consortium of industry, academic, and health care partners has developed reusable middleware components integrated using the HOLON architecture. Engineering approaches for multi-organization systems development, lessons learned in developing layered object-oriented systems, security and confidentiality considerations, and functionality for nationwide telemedicine applications are discussed.

Baby CareLink: development and implementation of a WWW-based system for neonatal home telemedicine

Baby CareLink is a multifaceted telemedicine application designed to provide individualized information and support to families of Very Low Birth Weight infants. We believe that this innovative use of WWW and telemedicine technologies will improve family satisfaction and clinical care. In conjunction with improvements in family involvement, discharge planning, education, and follow-up enabled by other CareLink components, this system may allow infants to transition home even earlier in their hospital stay and thereby provide a clear cost savings. This paper discusses the CareLink architecture and lessons learned in implementing a telemedicine link with families at home from an in-hospital clinical unit.

Telematics in the neonatal ICU and beyond: improving care for high-risk newborns and their families

The Beth Israel-Deaconess has recently been awarded one of 19 contracts from the National Library of Medicine (NLM) to develop, implement and test a telemedicine application to support the care of Very Low Birth Weight Infants. This project is the only one to focus on the care of newborns. We believe that this project will provide a new national approach to managing the care of high-risk newborns by leveraging evolving communication technology.

Engineering protein mechanics: inhibition of concerted motions of the cellular retinol binding protein by site-directed mutagenesis

Recently we reported on the dynamic properties of the cellular retinol binding protein, a member of the fatty acid binding protein family. A few conserved glycines were identified as important for producing the conformational changes necessary for the uptake and release of retinol. Here, we describe a multidisciplinary analysis of a genetically engineered mutation of one of these glycines (Gly67), designed to inhibit an observed hinge bending motion. The correctly folded mutant protein is unable to bind retinol. Analysis of the molecular dynamics simulations of the mutant and wild type protein using the essential dynamics method shows that the mutation indeed inhibits the hinge bending motions which are important for retinol binding.

A method for determining transmembrane protein structure

A simple and rapid protein chemical approach for determining the transmembrane structure of membrane proteins is described. The method involves single substitutions of consecutive amino acid residues, within putative transmembrane segments, to cysteine. This is followed by the analysis of their susceptibility to modification by maleimides with different physico-chemical properties. Fluorescein-5-maleimide (FM), being hydrophilic, modified only residues located in the aqueous environment, while the hydrophobic reagent, benzophenone-4-maleimide (BM) modified residues exposed to the lipid phase. These probes are large enough to cause an increase in the molecular weight of relatively small membrane proteins or polypeptide fragments, which is detectable by SDS-PAGE. Modification by much smaller probes, such as N-ethylmaleimide (NEM), could also be monitored indirectly by the ability to prevent SDS-solubilized protein from being modified with fluorescein-5-maleimide. The approach is demonstrated with the proteolipid complex of the vacuolar H(+)-ATPase expressed in yeast and with the putative Isk K(+)-channel expressed and radiolabelled in E. coli. The advantages of this approach are: (1)it is rapid, easy and inexpensive, (2) detection of the modification of engineered cysteines is simple, (3) it requires only minute quantities of the protein, (4) the protein does not require purification, (5) a broad range of maleimides with different physico-chemical properties can be used, (6) the structure can be investigated under native conditions and does not require protein reconstitution into artificial bilayers.

The first putative transmembrane helix of the 16 kDa proteolipid lines a pore in the Vo sector of the vacuolar H(+)-ATPase

The 16 kDa proteolipid is the major component of the vacuolar H(+)-ATPase membrane sector, responsible for proton translocation. Expression of a related proteolipid from the arythropod Nephrops norvegicus in a Saccharomyces strain in which the VMA3 gene for the endogenous proteolipid has been disrupted results in restored vacuolar H(+)-ATPase function. We have used this complementation system, coupled to cysteine substitution mutagenesis and protein chemistry, to investigate structural features of the proteolipid. Consecutive cysteines were introduced individually into putative transmembrane segment 1 of the proteolipid, and at selected sites in extramembranous regions and in segment 3 and 4. Analysis of restored vacuolar H(+)-ATPase function showed that segment 1 residues sensitive to mutation to cysteine were clustered on a single face, but only if the segment was helical. Only residues insensitive to mutation could be covalently modified by the cysteine-specific reagent fluorescein 5-maleimide. A cysteine introduced into segment 3 was the only residue accessible to a relatively hydrophobic reagent, suggesting accessibility to the lipid phase. Analysis of disulphide bond formation between introduced cysteines indicates that the first transmembrane alpha-helices of each monomer are adjacent to each other at the centre of the proteolipid multimeric complex. The data are consistent with a model in which the fluorescein maleimide-accessible face of helix I lines a pore at the centre of a hexameric complex formed by the proteolipid, with the mutationally sensitive face oriented into the protein core. The implications for ion-transport function in this family of proteins are discussed in the context of this structural model.

Membrane insertion and assembly of ductin: a polytopic channel with dual orientations

Ductin is a highly conserved and polytopic transmembrane protein which is the subunit c component of the vacuolar H(+)-ATPase (V-ATPase) and a component of a connexon channel of gap junctions. Previous studies have suggested that ductin in the V-ATPase has the opposite orientation of ductin in a connexon. Using an in vitro translation system coupled to microsomes derived from the endoplasmic reticulum, we show that ductin is co-translationally inserted into the membrane bilayer, suggesting a dependency on the signal recognition particle for synthesis. By attaching a C-terminal polypeptide derived from beta-lactamase and by using cysteine replacement coupled to chemical labelling, we show that ductin is inserted into the microsomal membrane in both orientations in similar proportions. In contrast, squid rhodopsin appears to be inserted in a single orientation. Changing conserved charged residues at the N-terminus of ductin does not affect the ratio of the two orientations. Once in the microsomal membrane, ductin assembles into an oligomeric complex which contains a pore accessible to a water-soluble probe, reminiscent of the ductin complex found in the V-ATPase and a connexon.

Functional properties of a hybrid vacuolar H(+)-ATPase in Saccharomyces cells expressing the Nephrops 16-kDa proteolipid

The hydrophobic 16-kDa polypeptide which forms gap-junction-like structures in the crustacean Nephrops norvegicus is a member of a highly conserved family of proteolipids involved in a variety of membrane transport functions in eukaryotic cells. This family also includes the product of the Saccharomyces cerevisiae VMA3 gene which encodes an integral membrane component of the vacuolar membrane H(+)-ATPase. The cDNA for the Nephrops proteolipid complements a mutation in the yeast VMA3 gene, resulting in assembly of a hybrid H(+)-ATPase comprising yeast catalytic subunits and Nephrops integral membrane components. The hybrid vacuolar ATPase was capable of ATP hydrolysis which was coupled to proton translocation and showed inhibitor binding and enzymological properties similar to those of wild-type V-ATPases (Km for ATP, 0.4 mM), suggesting that both yeast and crustacean proteolipids share conserved structure at regions of protein interaction. To facilitate isolation of the Nephrops proteolipid by affinity chromatography on a Ni(2+)-binding support, six C-terminal histidine residues were added to the proteolipid. This modification did not prohibit assembly into the hybrid H(+)-ATPase, although the resultant enzyme did have a markedly elevated Km (1.8 mM). The membrane-bound Vo sector of the ATPase was isolated by the affinity-chromatography procedure and reconstituted into synthetic vesicles. This complex was found to be impermeable to small cations in the absence of catalytic ATPase subunits either in situ in the vacuolar membrane or in the reconstituted system. The functional significance of this impermeability and the structure/function relationships between proteolipids from different sources are discussed.

Evidence for a common structure for a class of membrane channels

Electron microscopic analysis of gap-junction-like structures isolated from an anthropod (Nephrops norvegicus) and composed of a 16-kDa polypeptide, show the functional unit to be a star-shaped hexamer of protein arranged around a central channel which runs perpendicular to the plane of the membrane. Estimations of the molecular volume carried out on an averaged projection are consistent with a subunit mass of 16-18 kDa. Fourier transform infrared spectroscopy indicates a high alpha-helical content for the protein, supporting secondary-structure predictions of four transmembrane alpha helices/monomer. The averaged projection shows a close resemblance to a hexamer of the 16-kDa protein built on the basis of a four alpha-helical bundle [Finbow, M. E., Eliopoulos, E. E., Jackson, P. J., Keen, J. N., Meagher, L., Thompson, P., Jones, P. C. & Findlay, J. B. C. (1992) Protein Eng. 5, 7-15]. The reconstructed image is also similar to that obtained for gap-junction-like channels isolated from a related arthropod [Homarus americanus; Sikerwar, S. S., Downing, K. H. & Glaeser, R. M. (1991) J. Struct. Biol. 106, 255-263] whose protein content was unknown but which we demonstrate may be composed of a related 16-kDa protein. Previous studies have shown a high sequence identity of the Nephrops 16-kDa protein with the 16-kDa proteolipid subunit c of the vascular H(+)-ATPase, both of which in turn bear similarity to the 8-kDa proteolipid subunit of the F1F0-ATP synthase. Expression of cDNA coding for the Nephrops 16-kDa protein in Saccharomyces cerevisiae, in which the endogenous gene coding for the V-ATPase proteolipid has been inactivated, restores V-ATPase activity and cell growth.

Assessing physiological benefit from domiciliary nebulized bronchodilators in severe airflow limitation

In steroid resistant chronic obstructive pulmonary disease (COPD) we assessed the effect of q.i.d. domiciliary nebulized fenoterol (F) 1.25 mg and ipratropium (I) 0.5 mg for three weeks in a placebo-controlled, randomized, double-blind, crossover study. The twenty patients studied (mean forced expiratory volume in one second (FEV1) 0.8 l) all showed less than 20% increase in FEV1 to 200 micrograms inhaled salbutamol (S) and less than 20% increase in peak expiratory flow rate (PEFR) after 2 weeks prednisolone therapy. Respiratory function tests, 5 min walking distance (5 MWD), visual analogue scales (VAS) for breathlessness, oxygen cost diagrams and reversibilities were performed weekly for three weeks with patients on their usual therapy, after three weeks domiciliary F+I, after three weeks saline and, finally, after a further three weeks on usual therapy again. Primary end-points, selected prior to unblinding, were mean home twice daily PEFR, trapped gas volume, FEV1 and 5 MWD. Home PEFR rose from 164 l.min-1 on saline to 196 l.min-1 on F+I (p = 0.0001). Secondary end-point analysis revealed a fall in home inhaler usage and a rise in VAS. Using the criterion of +15% and greater than 20 l.min-1 increase in home PEFR, 11 out of 20 patients had a "positive" trial. We suggest that such patients, but not others, benefit from long-term, nebulized beta 2-agonist and ipratropium. Trials using home PEFR recordings should be used to identify them.

Assessing physiological benefit from domiciliary nebulized bronchodilators in severe airflow limitation

In steroid resistant chronic obstructive pulmonary disease (COPD) we assessed the effect of q.i.d. domiciliary nebulized fenoterol (F) 1.25 mg and ipratropium (I) 0.5 mg for three weeks in a placebo-controlled, randomized, double-blind, crossover study. The twenty patients studied (mean forced expiratory volume in one second (FEV1) 0.8 l) all showed less than 20% increase in FEV1 to 200 micrograms inhaled salbutamol (S) and less than 20% increase in peak expiratory flow rate (PEFR) after 2 weeks prednisolone therapy. Respiratory function tests, 5 min walking distance (5 MWD), visual analogue scales (VAS) for breathlessness, oxygen cost diagrams and reversibilities were performed weekly for three weeks with patients on their usual therapy, after three weeks domiciliary F+I, after three weeks saline and, finally, after a further three weeks on usual therapy again. Primary end-points, selected prior to unblinding, were mean home twice daily PEFR, trapped gas volume, FEV1 and 5 MWD. Home PEFR rose from 164 l.min-1 on saline to 196 l.min-1 on F+I (p = 0.0001). Secondary end-point analysis revealed a fall in home inhaler usage and a rise in VAS. Using the criterion of +15% and greater than 20 l.min-1 increase in home PEFR, 11 out of 20 patients had a "positive" trial. We suggest that such patients, but not others, benefit from long-term, nebulized beta 2-agonist and ipratropium. Trials using home PEFR recordings should be used to identify them.

Reversibility tests in chronic obstructive airways disease: their predictive value with reference to benefit from domiciliary nebuliser therapy

The role of short-term tests of reversibility in selecting patients with COAD for long-term nebuliser therapy is uncertain. In a double-blind placebo-controlled crossover study we have examined the correlation between short-term reversibility and response to a home nebuliser. We studied 20 patients with severe COAD (mean age 66, mean FEV1 0.81 l) and little reversibility (less than 20% increase in FEV1 post-inhaled salbutamol 200 micrograms and less than 25% increase in peak expiratory flow rate, PEFR, on oral steroids). PEFR, spirometry, lung volumes and airways conductance were recorded before and 1 h after a mixture of nebulised ipratropium 0.5 mg and fenoterol 1.25 mg. Patients then recorded twice-daily PEFR at home while they received nebulised ipratropium plus fenoterol, or saline placebo, four times a day for three week blocks using a double-blind cross over protocol. Mean PEFR on home nebuliser rose from 164 l m-1 (placebo) to 196 l m-1 (ipratropium plus fenoterol), paired t-test P = 0.0001. Correlation coefficients between short-term response for PEFR, spirometry and lung volumes, and improvement in home PEFR on nebulised ipratropium plus fenoterol, were all poor (R = -0.37-0.35, P = 0.83-0.11). We conclude that in severe COAD, reversibility tests of PEFR, spirometry and lung volumes do not correlate with response to a home nebuliser. Home measurements of PEFR are probably the best objective method of assessing response to a home nebuliser in such patients.

Growth rates and patterns of organs and tissues in the bovine fetus

Ninety-two purebred Jersey fetuses from clinically normal dams derived from a variety of sources but unexposed to experimental infection, were killed between 80 and 260 days after conception and dissected to provide basic parameters of a normal population. Organs and tissues were weighed and measured and the equations for the regression of the values on fetal age evaluated. Growth followed a sigmoid curve with rapid changes in growth rate between 140 and 170 days' gestation. While a few variables increased their growth rate over the late fetal period, the majority maintained a low even rate of growth. Thyroid and cerebellum weights showed a marked reduction in growth rate at this time. Long bone length and crown-anus length were the most predictable parameters for a given gestational age.

Pulp response to collagen and glutaraldehyde in pulpotomized primary teeth of baboons

This investigation assessed histologically the pulp tissue reaction to glutaraldehyde (GA) and to a commercial collagen preparation in pulpotomized primary teeth of baboons. One hundred and eighty-eight primary teeth were pulpotomized; in half of them inflammation was induced prior to the treatment. The teeth were divided into five groups: in three of them GA was used as a pulp dressing and applied for 1 min (group 1), 5 min (group 2), or mixed into the paste (group 3); collagen was used in group 4 and in group 5 (control) IRM was placed directly over the pulp stumps. Follow-up times were two, eight, and 24 weeks. Total necrosis was observed only in the collagen group. Partial necrosis and severe inflammation also were seen mainly in this group, and when the GA was incorporated into the paste. Slight to moderate inflammation was evident in all groups two and eight weeks postoperatively; however, 78% of the teeth of group 2 (GA 5 min) were inflammation-free after 24 weeks. Partial dentin bridges were seen in 92% of the teeth of the control group, in 82% of group 2, and 50% each of groups 1 and 3 eight weeks postoperatively. Dentin bridges were present in only 4% of the collagen group. After 24 weeks, all the teeth in group 2 and 83% of group 1 had dentin bridges. We conclude that Zyderm (Colagen Corp. Palo Alto, CA) led to unacceptable results, 5 min application of GA presented the best healing response, and GA 1 min and IRM also were satisfactory.

Immunochemistry and immunogenicity of low molecular weight human salivary mucin

The purposes of this study were to examine the immunogenicity of the low molecular weight human salivary mucin (MG2) and determine its distribution within major and minor human salivary glands. Anti-MG2 sera were produced in Balb/c mice by a variety of immunization schedules. Chromatographically or electrophoretically purified MG2 and partially purified mucin chromatographic fractions exposed to mild denaturing conditions were not immunogenic. Only MG2 without prior exposure to urea or guanidine was able to elicit an immune response. A murine anti-MG2 monoclonal antibody (clone 1/F9) was produced and its monospecificity confirmed by immuno-dot blotting and SDS-PAGE Western transfer. Clone 1/F9 (IgG1; kappa) was of moderate affinity and was directed to a Pronase- and TPCK trypsin-sensitive but periodate-resistant epitope which was not blood group- or sialic acid-specific. Immunocytochemical studies of frozen tissue sections with clone 1/F9 using both indirect and direct methods revealed that MG2 was more heterogeneously distributed within submandibular than labial glands and was not found in parotid or palatine glands. The use of a polyclonal rabbit anti-MG2 reagent in either frozen or paraffin-embedded tissues gave the same immunocytochemical results as those obtained with the monoclonal antibody.

Estimation of the developmental age of the bovine fetus and newborn calf

Jersey cows from several herds provided 97 fetuses and 24 calves at fixed gestational intervals between 80 and 290 days after conception. The fetuses and calves were killed, weighed and measured and, after dissection, the sizes and weights of a range of skeletal and soft tissues were recorded. Six morphological measurements emerged as most suitable for the determination of developmental age in the normal fetus. By plotting their mean values and 95 per cent tolerance limits, the rates of growth and the variability of each measurement were defined. Long bone length was the most useful single measurement for predicting the developmental age of the fetus. Brain weight, bodyweight, crown-anus length and long bone length showed curvilinear growth patterns; age prediction equations derived from these measurements are complicated to use and additional simplified formulae have been derived. The number of appendicular ossification centres also had predictive value, but it could not be used to determine fetal developmental age between 100 and 160 days gestation.

Immunochemistry of high molecular-weight human salivary mucin

The purpose of this study was to determine the distribution of mucin glycoprotein 1 (MG1) within submandibular, parotid, labial and palatine salivary tissues. Formalin-fixed and frozen tissue sections were examined histochemically with PAS, Alcian blue and Meyer's mucicarmine, and immunocytochemically with an anti-mucin glycoprotein 1 monoclonal antibody (clone 3/E8). Clone 3/E8 was produced in Balb/c mice using mucin-enriched chromatographic fractions from submandibular-sublingual saliva. The monospecificity of 3/E8 was confirmed by immuno-dot blotting and SDS-PAGE/electrophoretic transfer. Clone 3/E8 (IgG1; kappa) was of moderate affinity, and was directed to a carbohydrate-containing, TPCK-trypsin-insensitive and pronase-insensitive epitope on this mucin, which was not blood-group specific. The location of mucin glycoprotein 1 was determined by both indirect (peroxidase-antiperoxidase) and direct methods. Mucin glycoprotein 1 was localized within all labial acini examined, but was not found within parotid tissues. Histochemical methods stained all submandibular, palatine and labial acini, but immunocytochemistry with monoclonal antibody revealed heterogeneous staining with clone 3/E8 in submandibular and palatine tissues. These findings suggest the presence of mucin glycoprotein 1-specific acinar cell subpopulations within human submandibular and palatine salivary tissues.

Oral mucosal pellicle. Adsorption and transpeptidation of salivary components to buccal epithelial cells

The present investigation was carried out to examine the mechanism(s) whereby salivary molecules interact with human buccal epithelial cells. By utilizing antiserum against human parotid saliva, selected salivary components were detected by electrophoretic-transfer analysis of 1.5% SDS extracts of epithelial cells. Incubation of the cells and their aqueous cell-free extracts with 125I-labelled parotid saliva resulted in the formation of an iodinated high-molecular-mass complex which was not present in 125I-labelled saline alone. Formation of this complex was time-dependent and was inhibited by treating the buccal epithelial cells or their cell-free extracts with EGTA, iodoacetamide, N-ethylmaleimide or by heating at 100 degrees C for 15 min. The epithelial cells also promoted incorporation of [14C]putrescine into high-molecular-mass complexes whose formation was inhibited by iodoacetamide, unlabelled putrescine and EGTA. Cell extracts mediated cross-linking of monodansylcadaverine into alpha-casein, and this interaction was inhibited by iodoacetamide. Significant amounts of radioactivity were recovered with the epithelial-cell envelopes after exhaustive extraction of 125I-saliva- or [14C]putrescine-treated epithelial cells with 4% (w/v) SDS/10% (v/v) beta-mercaptoethanol. The incorporation of radioactivity into epithelial-cell envelopes was inhibited by pretreatment of the cells with putrescine, EGTA, iodoacetamide, or heating at 100 degrees C for 15 min. These data suggest that: (1) oral mucosal pellicle is formed by the selective adsorption of saliva to the epithelial-cell plasma membrane and its associated cytoskeleton; and (2) the adsorbed salivary components may be cross-linked to each other or the epithelial cytoskeleton by epithelial transglutaminases.

Biochemical and biophysical comparison of two mucins from human submandibular-sublingual saliva

A high-molecular-weight mucin-glycoprotein (MG1) was isolated from human submandibular-sublingual saliva and was comprised of 14.9% protein, 29.0% N-acetylglucosamine, 9.4% N-acetylgalactosamine, 10.5% fucose, 24.2% galactose, 0.9% mannose, 4.0% N-acetylneuraminic acid, and 7.0% sulfate. Carbohydrate units were O-glycosidically linked and ranged in size from 4 to 16 residues. The biophysical properties of MG1 were compared to those of a smaller mucin (MG2) also isolated from submandibular-sublingual saliva. Fluorescence spectroscopy demonstrated that MG1 bound both 1-anilino-8-naphthalenesulfonate (ANS) and N-phenyl-1-naphthylamine (NPNA) in stable hydrophobic binding sites (melting temperature, 47 +/- 2 degrees C), whereas MG2 did not bind these hydrophobic probes. These hydrophobic domains occurred on nonglycosylated or naked portions of MG1 since Pronase treatment eliminated ANS binding. Reduction of disulfide bridges in MG1 increased the number of available hydrophobic binding sites. High ionic strength (0 to 2 M NaCl) had no effect on ligand binding, whereas lowering pH (9 to 2) increased ANS binding without affecting NPNA complexation. Circular dichroism (CD) data suggested that MG1's carbohydrate chains dominated its spectrum. In contrast, the peptide backbone dominated the CD spectrum of MG2. Collectively, the results of this study indicate that human submandibular-sublingual saliva contains two structurally distinct mucins.

Effect of factors associated with insemination on calving rate in dairy cows

The results of 7569 inseminations performed on 6007 cows in 94 dairy herds were used to investigate the relative importance of time of insemination, bull and inseminator on calving rates in dairy cows. Although the time of insemination in relation to the first observation of oestrus was shown to have some effect, the effect was minimal during the first 24 hours. The maximum difference in expected calving rates between cows served with semen from groups of bulls with a history of either low or high fertility was 20 per cent, and the maximum difference in expected calving rate between cows inseminated by groups of inseminators who had consistently achieved either low or high fertility was 13 per cent.

Maternally-derived antibodies to porcine parvovirus and their effect on active antibody production after vaccination with an inactivated oil-emulsion vaccine

Two sows which had been vaccinated with an oil-emulsion porcine parvovirus vaccine, and had developed high haemagglutination-inhibiting antibody levels to the virus, farrowed three successive litters each, a total of 74 piglets. Serum samples from these piglets were tested for haemagglutination-inhibiting antibody at birth, three and 17 days after birth, and at monthly intervals thereafter to study the decline of maternally-derived antibody. Regression curves were constructed from the data to show the projected pathway (mean and 95 per cent tolerance limits) of the decline of maternally-derived antibody. Approximately half the pigs still had positive titres of up to 1/160 at six months old, and traces of antibody were detected in a few pigs at nine months. Thus, even at the onset of breeding some gilts can have maternally-derived antibody which may interfere with their ability to develop active immunity to porcine parvovirus. From the same litters three groups of 12 pigs were selected randomly and were vaccinated with a single dose of the oil-emulsion vaccine at 70 days, 130 days or 190 days respectively. Despite the presence of moderate to high titres of maternally-derived antibody, especially in the younger pigs, all of those vaccinated showed strong and long lasting antibody responses to the vaccine. High serum antibody titres at the time of vaccination seemed to depress the response to the vaccine slightly but the effect was not statistically significant. These results have important implications for prevention of reproductive failure induced by porcine parvovirus.

Structural aspects of salivary glycoproteins

The protective functions of saliva are attributed, in part, to its serous and mucous glycoproteins. We have studied, as representative molecules, the proline-rich glycoprotein (PRG) from human parotid saliva and the high (MG1) and low (MG2) molecular weight mucins from submandibular-sublingual saliva. PRG (38.9 kDa) contains 40% carbohydrate consisting of 6 triantennary N-linked units and a single peptide chain of 231 amino acids, 75% of which = PRO + GLY + GLN. PRG's secondary structure is comprised of 70% random coil (naked regions) and 30% beta-turns (glycosylated domains). MG1 (greater than 10(3) kDa) contains 15% protein (several disulfide linked subunits), 78% carbohydrate (290 units of 4-16 residues), 7% sulfate, and small amounts of covalently linked fatty acids. MG2 (200-250 kDa) contains 30% protein (single peptide chain), 68% carbohydrate (170 units of 2-7 residues), and 2% sulfate. The major carbohydrate units of MG2 are: NeuAc alpha 2,3Gal beta 1,3GalNAc,Gal beta 1,3GalNAc, and Fuc alpha 1,2Gal beta 1,3GalNAc. MG1 contains hydrophobic domains, as evidenced by its ability to bind fluorescent hydrophobic probes; MG2 does not. Collectively, the biochemical and biophysical comparisons between MG1 and MG2 indicate that these two mucins are structurally different. Several functional properties of MG1, MG2, and PRG have been examined, including their presence in two-hour in vivo enamel pellicle, binding to synthetic hydroxyapatite, lubricating properties, and interactions with oral streptococci. The data presented suggest that these glycoproteins may have multiple functions which are predicated, in part on their carbohydrate units. The potential significance of the structure-function relationships of these glycoproteins to the oral ecology is discussed.

An investigation of bovine serum copper levels in Lincolnshire and South Humberside

Analysis of more than 2000 bovine serum samples showed a large monthly variation in copper levels. There was also a difference in levels between beef and dairy cows although all showed the same monthly pattern. This monthly variation was correlated with rainfall; the higher the rainfall the lower the copper level. The interpretation of single herd blood copper values must be considered carefully in view of this variation.

An evaluation of five serological tests for the detection of antibody to bovine herpesvirus 1 in vaccinated and experimentally infected cattle

More than 300 bovine sera from a previously reported vaccination and challenge trial were tested for antibodies to bovine herpesvirus 1 (BHV1) by five serological assays: enzyme-linked immunosorbent assay (ELISA) for IgM and IgG, passive haemagglutination (PHA), and two methods of virus neutralisation (VN). In a statistical comparison of ELISA (IgG), PHA and VN results, the assays showed highly significant correlations (P less than 0.01). The sensitivities of ELISA and 24-hour neutralisation tests were similar, in contrast to passive haemagglutination and one hour neutralisation which failed to detect BHV1 antibodies in some low titre sera.

Cow milk yield and composition before development of Escherichia coli mastitis

High milk yield, low milk fat and low milk protein were considered as possible predisposing factors to bovine Escherichia coli mastitis. Morning and afternoon milk yields were recorded in 46 Friesian cows later developing E coli mastitis and compared with 92 uninfected controls. Animals developing E coli mastitis gave a significantly higher milk yield than controls. The overall morning: afternoon ratio was (mean +/- se) 1.66 +/- 0.41, with no difference in ratio for the two groups. Further studies on 85 animals later developing E coli mastitis, and 192 controls, in four Friesian herds did not reveal differences in milk fat content (except as related to yield), milk protein or in the interrelationship of days of lactation, milk protein or in the interrelationship of days of lactation, milk fat and milk protein in the two groups. Again there was a correlation between high milk yield and a tendency to develop E coli mastitis but this may have been an age effect in both investigations. No correlation between milk yield and mastitis severity was detected. High yielders which succumbed to E coli mastitis in three herds were producing less milk than mastitis-free controls in the fourth herd which suggests that the correlation is not with yield per se.

Seasonal variations in serum progesterone levels in pregnant sows

In the autumn and winter of 1979 and the spring and summer of 1980 serum samples were taken from approximately 20 sows at between 40 and 90 days of gestation in each of seven commercial herds. In most of these herds progesterone concentrations were significantly lower in the autumn than in the other three seasons. Between June 1980 and June 1981 every pregnant sow in a further herd of 250 sows was sampled at 25 to 30 days and at 70 to 91 days of gestation. Seasonal differences in progesterone concentrations were again evident, with the concentrations rising from their lowest in August, September and October to a peak in March. Comparisons between the early and late pregnancy progesterone levels from sows sampled in this herd at different times of the year suggested that corpora lutea which were formed in the summer and early autumn were fully competent and responsive, but that their lower hormone production was possibly the result of reduced luteotrophic stimulation. These findings are pertinent to the pathophysiology of the autumn abortion syndrome and other seasonal reproductive problems in sows.

Evidence for and partial characterization of three major and three minor chromatographic forms of human neutrophil myeloperoxidase

Myeloperoxidase (MPO) is an enzyme found in the azurophil granules of neutrophils. Cation-exchange chromatography on carboxymethyl-cellulose previously has been used to demonstrate the heterogeneity of the peroxidase enzymes isolated from human neutrophils. In this study, fast protein liquid chromatography (FPLC) was used to separate and purify three major (I, II, and III) and three minor (IIa, IIIa, IIIb) forms of MPO from isolated neutrophil granules. Purity was confirmed by polyacrylamide gel electrophoresis in the presence of cetyltrimethylammonium bromide (CETAB-PAGE), by crossed immunoelectrophoresis, and by spectral characteristics. All three major forms were indistinguishable by immunodiffusion against rabbit antiserum, scanning spectrophotometry, and amino acid composition. They differed in their elution from a cation-exchange resin, inhibition by 3-amino-1,2,4-triazole, migration rate in CETAB-PAGE, and subunit molecular weight. Subunit molecular weight was examined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). All three major forms appeared to consist of heavy (H), intermediate (M), and light (L) peptides. The M peptide appeared to be derived from the H subunit. All L subunits exhibited a molecular weight of 14,500. The molecular weights for the H subunits varied, and were 60,000, 59,000, and 57,000 for MPO I, II, and III, respectively. The molecular weights for the M peptides were 44,100, 43,000, and 42,000 for MPO I, II, and III, respectively. The treatment of neutrophils, granules, and extracts with protease inhibitors and sodium azide did not block the appearance of three major forms of MPO. Thus, neither protease activity nor MPO autooxidation during extraction and purification procedures is responsible for the appearance of multiple chromatographic forms of MPO derived from human neutrophils.