Gamma interferon functions in resistance to Cryptosporidium parvum infection in severe combined immunodeficient mice.

Severe combined immunodeficient (SCID) adult mice are relatively resistant to Cryptosporidium parvum infection, even though they are deficient in both T- and B-cell function. The requirement for gamma interferon (IFN-gamma) in this resistance was examined by treatment of these mice with monoclonal antibody to IFN-gamma. SCID mice injected intraperitoneally with monoclonal anti-IFN-gamma 4 h before and three times weekly after challenge with C.

Bovine L-selectin: a peripheral lymphocyte homing receptor.

The cDNA clone encoding for the bovine peripheral lymph node homing receptor (L-selectin) was isolated and sequenced. The predicted amino acid sequence of bovine L-selectin showed an overall high identity with that of human and murine L-selectin. However, the cytoplasmic tail of bovine L-selectin showed little similarity to that of human and murine L-selectin.

Simplified enzymatic assay of angiotensin-converting enzyme in serum.

We report a simple, enzymatic method for determining angiotensin-converting enzyme (ACE; EC 3.4.15.

Resistance of severe combined immunodeficient mice to infection with Cryptosporidium parvum: the importance of intestinal microflora.

Cryptosporidium parvum is a protozoan parasite which colonizes intestinal epithelium, causing transient diarrheal illness in immunocompetent hosts and severe chronic disease in immunocompromised hosts. We examined the resistance of severe combined immunodeficient mice, either bearing intestinal flora or germfree, to intestinal infection with C. parvum.

Mechanical considerations in using tensioned wires in a transosseous external fixation system.

Factors that affect wire tension were examined using external mechanical testing units as well as in-line load cells. The circular external fixator with wires supported at each end exhibits a self-stiffening effect such that wire stiffness increases with wire deflection. Mechanical slippage between wire and fixation bolt is the primary reason for loss of wire tension.

Evidence for conservation of peripheral lymphocyte homing receptors between the bovine, murine and human species.

In rodents and humans, lymphocytes circulate throughout the body and return preferentially to their tissues of origin via a process termed homing. The specificity of homing is controlled by the binding of tissue-specific receptors on lymphocytes to ligands on specialized high-walled endothelial venules (HEV) found in lymphoid tissue. The murine and human peripheral lymphocyte homing receptors (PLHR) have been characterized and shown to be similar to each other.

Sequence of the bovine CD44 cDNA: comparison with human and mouse sequences.

CD44 is a cell-surface glycoprotein involved in leukocyte adherence, T-cell activation and lymphocyte homing. We have isolated and sequenced a cDNA clone which encodes for bovine CD44. The predicted amino acid sequence of bovine CD44 has an overall high similarity with that of human and mouse CD44, 79.

Numbers and percent of T lymphocytes in bovine peripheral blood during the periparturient period.

To determine if periparturient immunosuppression in dairy cattle might be due to an alteration in total numbers of percent of T lymphocytes, we examined the numbers and percent of T lymphocyte subsets in peripheral blood from periparturient dairy cows, some of which received recombinant bovine granulocyte colony stimulating factor (rbG-CSF) during the study. Beginning 2 weeks preparatum through 4 weeks postpartum, peripheral blood mononuclear cells (PBMC) were collected and labeled with monoclonal antibodies to BoCD5, BoCD4, and BoCD8, and the percent of cells positive for each marker measured by flow cytometry. The percent of PBMC expressing BoCD5 (total T cells), and BoCD8 (T suppressor/cytotoxic cells) was not significantly different between the groups, or at different times before and after calving.

Characterization of bovine cellular and serum antibody responses during infection by Cryptosporidium parvum.

Cellular and serum antibody responses of calves were monitored for 23 days after oral inoculation of the calves with oocysts of Cryptosporidium parvum. In vitro blastogenic responses of peripheral blood lymphocytes were assessed after stimulation with a C. parvum preparation.

Nutrition and somatomedin. XXII: Molecular regulation of insulin-like growth factor-I during fasting and refeeding in rats.

The liver is thought to be the locus of nutritional/hormonal regulation of circulating insulin-like growth factor-I (IGF-I). To probe the basis of nutritional regulation, we examined changes in serum IGF-I, hepatic content of extractable IGF-I immunoreactivity (a high Mr putative precursor) and hepatic IGF-I mRNA during fasting and refeeding in rats. Preliminary studies revealed that the hepatic level of IGF-I mRNA was consistently reduced only after food was withheld for 3 days, so the effects of refeeding were subsequently examined in such animals.

Cryptosporidium parvum infection in mice: inability of lymphoid cells or culture supernatants to transfer protection from resistant adults to susceptible infants.

The ability of murine lymphoid cells or culture supernatant fractions to transfer protection against Cryptosporidium parvum was examined. Spleen or mesenteric lymph node (MLN) cells were taken from adult mice resistant to C. parvum and given either directly or following in vitro culture to infant mice.

Susceptibility of mast cell-deficient W/Wv mice to Cryptosporidium parvum.

Mast cell-deficient W/Wv infant mice were similar to normal mice in their susceptibility to and recovery from infection with the intestinal protozoan Cryptosporidium parvum. W/Wv adult mice were significantly more susceptible to primary infection than were normal adult mice, but both groups recovered at a similar rate.

Nutrition and somatomedin. XXIII. Molecular regulation of IGF-I by amino acid availability in cultured hepatocytes.

The poor growth associated with protein-calorie malnutrition occurs despite circulating growth hormone levels that are normal or elevated and is thought to be mediated partly by blunted generation of insulinlike growth factor I (IGF-I) in the liver. To explore underlying mechanisms, we asked whether altered availability of amino acids could regulate hepatic IGF-I release independent of the contributions of regulatory hormones. Normal rat hepatocytes were isolated by collagenase digestion and maintained in serum-free medium with fixed concentrations of insulin and dexamethasone.

Regulation and action of insulin-like growth factors at the cellular level.

Present understanding of IGF-1 as a growth factor mediating integration of nutritional-hormonal interactions indicates that IGF-1 acts in both an endocrine mode on distant targets and an autocrine-paracrine mode on local targets. In the liver, the combined presence of GH, insulin, and critical metabolic fuels such as essential amino acids results in increased levels of IGF-1 messenger RNA, increased production of a high-MW IGF-1 precursor, and increased release of IGF-1 into the circulation, permitting action on distant target tissues bearing specific receptors for IGF-1. The net effect is distant amplification of anabolic hormone action via IGF-1 acting in an endocrine mode.

Effects of preventing periparturient hypocalcemia in cows by parathyroid hormone administration on hematology, conglutinin, immunoglobulin, and shedding of Staphylococcus aureus in milk.

The effects of hypocalcemia at parturition on concentrations of serum immunoglobulin and conglutinin, number of bacteria shed into milk, and leukograms of dairy cows were investigated from -4 wk prepartum to 4 wk postpartum. Ten healthy multiparous Holstein cows were fed a high calcium diet to induce hypocalcemia at parturition. Five cows received intramuscular parathyroid hormone to prevent hypocalcemia at parturition.

Resistance of calves to Cryptosporidium parvum: effects of age and previous exposure.

Cryptosporidium parvum is a coccidian parasite that causes diarrheal disease in many vertebrate species, including young (less than or equal to 1 month old) calves. Older calves and adult cattle are resistant to infection. In this study, newborn calves were raised in isolation from C.

In vitro murine lymphocyte blastogenic responses to Cryptosporidium parvum.

Spleen and mesenteric lymph node lymphocytes from both Cryptosporidium parvum-exposed and unexposed mice were cultured with antigen (Ag) prepared from C. parvum oocysts. Spleen lymphocytes from oral-, intraperitoneal-, or oral + intraperitoneal-exposed mice did not respond significantly (P greater than 0.

Extravasation of lymphocytes via paracortical venules in sheep lymph nodes: visualization using an intracellular fluorescent label.

In rodents and humans, lymphocytes extravasate into lymph nodes via specialized paracortical venules lined with high endothelium (HEV). Sheep and other ruminants do not have morphologically defined HEV in their lymph nodes. It has been assumed that lymphocyte extravasation in these species proceeds via analogous structures; i.

Preliminary studies of mineralization during distraction osteogenesis.

Distraction osteogenesis by the Ilizarov method was performed on 20 dogs. Mineralization at the site of the left tibial metaphyseal lengthening was measured by weekly quantitative computer tomography (QCT) using the contralateral tibia as a control. Four dogs each were killed on Days 7, 14, 21, and 28 of distraction in order to correlate QCT with microradiology, nondecalcified histology, quantitative calcium analysis, and scanning electron microscopy.

Randomized, controlled trial of clonidine for smoking cessation in a primary care setting.

Clonidine hydrochloride has been reported to reduce tobacco withdrawal symptoms and facilitate smoking cessation. We enrolled 185 subjects, 92 receiving clonidine and 93 receiving placebo, in a randomized, double-blind study of clonidine for smoking cessation in a primary care setting. Clonidine had no demonstrable effect on withdrawal (8 of 11 measures favoring placebo).

Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvum infection.

Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvum infection were examined. Six calves were fed pooled colostrum that contained C parvum antibody, 6 times daily (at 4-hour intervals) for 7 days and then milk replacer for 7 days. Colostrum was obtained from healthy cows or cows inoculated parenterally with C parvum oocysts before parturition.

The effect of etomidate pretreatment on cerebral high energy metabolites, lactate, and glucose during severe hypoxia in the rat.

Etomidate was compared with thiopental with respect to preventing loss of brain high energy metabolites and accumulation of lactate during 20 min of hypoxemia (Pa2 of 16-19 mmHg) in rats with unilateral carotid artery ligation. Male Sprague-Dawley rats, anesthetized with halothane and nitrous oxide (N2O) in oxygen were randomly assigned to one of six groups. A normoxic control group which received 70% N2O in oxygen, a hypoxia group received no iv drug treatment (hypoxia-N2O), and four iv drug treatment groups (N2O was replaced by 70% nitrogen at the start of drug administration).

Local bone transportation for treatment of intercalary defects by the Ilizarov technique. Biomechanical and clinical considerations.

Ilizarov applied revolutionary methods for salvaging limbs with severe congenital, posttraumatic, or other acquired deformities. His methods, which use a universal system of ring external fixators with tensioned transosseous wires, were developed over the past 35 years at his institute in Kurgan, USSR. These noninvasive techniques have proved successful in over 300,000 patients (adults and children) treated for bone shortening and intercalary deficiency, angulatory and rotational malalignment, active infection, ischemia, joint contractures, and nonunions.

Function and regulation of lymphocyte-mediated immune responses: relevance to bovine mastitis.

Bovine mastitis is one of the most costly diseases to the dairy industry. Prospects for effective vaccines are limited by the variety of microorganisms capable of causing mastitis. An understanding of the physiologic and immunologic factors controlling the susceptibility of the cow to disease will lead to more rational approaches to prevention and control.