Bone morphometrics and tetracycline marking patterns in young growing American alligators (Alligator mississippiensis)

Nine young American alligators (Alligator mississippiensis) were injected at monthly intervals with tetracycline to determine the bone apposition rate and the resorption patterns over a 3-mo period. The periosteal apposition rate increased progressively over the 3-mo period from 2.99 microns/day to 5.94 microns/day. Endosteal apposition rate was much slower with incomplete tetracycline lines being observed on the endosteum. This suggests that most modeling-resorptive activities occur on the endosteal envelope.     

The effects of prostalene and alfaprostol as uterine myotonics, and the effect on postpartum pregnancy rate in the mare following daily treatment with prostalene

The effects of oxytocin and two prostaglandin (PG) F(2)alpha analogues, prostalene and alfaprostol, on uterine pressure in the mare were measured using balloon-tipped catheters connected to pressure transducers. The PGF(2)alpha analogues caused increased uterine pressure beginning 7 to 15 min postinjection and persisting for the duration of each 60 min recording session. Forty postpartum mares of light-horse breed were used to evaluate the effects of prostalene on postpartum pregnancy rate. Eighteen mares were injected by aseptic technique subcutaneously with 1 mg prostalene twice daily, beginning on the day of foaling (Day 0) and continuing for 10 consecutive days (Day 10) or until the mare was first bred at foal heat. Twenty-two postpartum mares were injected with 1.0 ml sterile saline by the same technique as the controls. Of treated mares, 76.9% were diagnosed pregnant after breeding versus 44.4% of the control mares (P = 0.07). Of treated mares, 66.7% bred at their second postpartum estrus became pregnant versus 28.6% of control mares (P = 0.03). Prostalene, given at 1 mg twice daily for 10 d postpartum, produced an increased pregnancy rate after both foal heat and second postpartum estrus breedings in the mare.     

Vitamin A excess alters membrane flow in rat liver

Pulse-chase methodology with [35S]methionine as label was employed to determine flow kinetics through the endoplasmic reticulum-Golgi apparatus-(lysosome-) secretory vesicle-plasma membrane export route in livers of animals receiving vitamin A excess by gavage. Overall fraction composition determined by morphometry and by analyses of marker enzymes was unchanged by vitamin administration. The vitamin modified the pattern of flow of proteins through the Golgi apparatus to the cell surface and to lysosomes. Altered flux was evidenced by a markedly reduced rate of labeling of lysosomes and a slightly increased rate of labeling of both total membrane proteins of the plasma membrane and of a specific membrane glycoprotein GP80. Also reduced was overall labeling of the Golgi apparatus. Differences in the rate or routes of trafficking of glycoproteins through the Golgi apparatus together with altered opportunities for processing might account for some of the alterations in glycoconjugate glycosylation associated with excess vitamin A administration.     

Structural Features of Human Monoamine Oxidase A Elucidated from cDNA and Peptide Sequences

Monoamine oxidase (MAO), an important enzyme for the degradation of amine neurotransmitters, has been implicated in neuropsychiatric illness. The amino acid sequence for one form of the enzyme, MAO-A, has been deduced from human cDNA clones and verified against proteolytic peptides. The covalent binding site for the flavin adenine dinucleotide (FAD) cofactor is near the C-terminal region. The presence of features characteristic of the ADP-binding fold suggests that the N-terminal region is also involved in the binding of FAD. These cDNAs should facilitate the study of the structure, function, and intracellular targeting of MAO, as well as the analysis of its expression in normal and pathological states.     

Expression of the Opc protein correlates with invasion of epithelial and endothelial cells by Neisseria meningitidis

Whereas capsulate strains of Neisseria meningitidis are dependent on pili for adhesion to human endothelial and epithelial cells, strains which lacked assembled pili and were partially capsule-deficient adhered to and invaded human endothelial and epithelial cells if they expressed the Opc protein. Bacteria expressing low or undetectable levels of Opc protein failed to adhere to or invade eukaryotic cells. In addition, the presence of OpaAC751 protein on the surface of bacteria did not increase bacterial interactions with host cells. Association of Opc-expressing bacteria was inhibited by antibodies against Opc. Invasion was dependent on the host-cell cytoskeletal activity and was inhibited by cytochalasin D. In some cells, infected at the apical surface, bacteria emerging from basal surface were detected by electron microscopy. Opc is found in diverse meningococci and may represent a common virulence factor which facilitates adherence and invasion by these bacteria.     

Identification and characterization of a B cell activation factor (BCAF) produced by a human T cell line

A human T cell line, Peer, that expresses the T cell helper phenotype produces discrete activation and growth factors for tonsillar B cells. The B cell activation factor produced by Peer is biochemically and physiologically distinct from other lymphokines known to enhance B cell proliferation, namely, interleukin 1, interleukin 2, interferon, and previously characterized B cell growth factors (BCGF). The BCGF produced by Peer is functionally similar to previously described BCGF but has a m.w. of approximately 30,000 daltons. The identification and characterization of a T cell-derived activation factor that can induce apparently resting (Go phase) B cells to enter S phase in the absence of an exogenous first signal has important implications in the additional dissection of the complex steps in the human B cell cycle.     

Characterization of a concanavalin A supernatant-derived idiotype-specific T helper cell factor

We have previously demonstrated the requirement of two T helper (Th) populations for the expression of plaque-forming cells (PFC) that bear the dominant cross-reactive idiotype (CRI) associated with the phenyltrimethylammonium (TMA) response (1). In addition to the classic major histocompatibility complex-restricted Th cell, the response was also dependent upon the so-called second order Th2 population, which binds to idiotypic determinants, is carrier specific, but does not require hapten linked to carrier for function. This cell type can be replaced by supernatant (Sn) media from concanavalin A (Con A)-stimulated naive spleen cells. This report involves the study of the Con A Sn derived factor(s) responsible for the expression of CRI bearing PFC populations. When the Brucella abortus (BA)-trinitrophenol (TNP) conjugated antigen is added to TNP-ovalbumin-primed A/J-derived spleen cells in culture, anti-TNP PFC are generated of which only less than or equal to 5% bear the CRI normally associated with anti-TMA antibodies. Upon addition of Con A Sn, the total number of generated anti-TNP PFC doubles, whereas the percentage and number of CRI+ PFC increases approximately eightfold to 10-fold. The factor(s) responsible for this activity are T cell derived, bear Jk serologic determinants, and can be detected in the Sn as early as 4 hr after Con A stimulation. The material appears to be late acting, because it can augment the CRI+ anti-TNP response when added as late as 24 hr before termination of the cultures. In addition, the factor(s) can be bound to and eluted from CRI+ anti-TMA and anti-TNP monoclonal antibodies coupled to Sepharose 4B beads, but not from their CRI- counterparts (i.e., CRI- anti-TMA and anti-TNP antibodies), nor from A/J normal mouse immunoglobulin-coupled beads. Most interestingly, the factor(s) also bind to and can be eluted from the TMA ligand coupled to Sepharose 4B, but not from TNP-Sepharose conjugates. All of these results are consistent with the support the contention that the factor(s) is derived from a Th2-like subpopulation. As assayed by standard protocols, the isolated material contains no T cell replacing factor, interleukin 2, or B cell growth factor activity.