Structures of the tetrahydrogenated menaquinones fromActinomadura angiospora,Faenia rectivirgula,andSaccharothrix australiensis

The structures of the tetrahydrogenated menaquinones fromActinomadura angiospora, Faenia rectivirgula, andSaccharothrix australiensis were determined by mass spectrometry and proton nuclear magnetic resonance spectrometry. The positions of saturation of the tetrahydrogenated menaquinones fromFaenia rectivirgula andSaccharothrix australiensis were units II plus III (counting from the ring system), whereas that ofActinomadura angiospora had units III and VIII hydrogenated. The tetrahydrogenated menaquinones fromFaenia rectivirgula andSaccharothrix australiensis are similar to those characterized from other Gram-positive taxa to date, whereas that fromActinomadura angiospora represents a hitherto unknown isomer.     

Nucleic acid studies on some heterofermentative lactobacilli: Description of Lactobacillus malefermentans sp.nov. and Lactobacillus parabuchneri sp.nov.

Chemotaxonomic studies were performed on some heterofermentative lactobacilli of uncertain taxonomic position. Two strains from beer and six strains from a variety of habitats were found to be distinct from each other and all other Lactobacillus species examined on the basis of DNA-DNA hybridizations and warrant new species for which the names L. malefermentans and L. parabuchneri , respectively, are proposed.     

Structural analogs of human insulin-like growth factor I with reduced affinity for serum binding proteins and the type 2 insulin-like growth factor receptor

Four structural analogs of human insulin-like growth factor I (hIGF-I) have been prepared by site-directed mutagenesis of a synthetic IGF-I gene and subsequent expression and purification of the mutant protein from the conditioned media of transformed yeast. [Phe-1,Val1,Asn2, Gln3,His4,Ser8, His9,Glu12,Tyr15,Leu16]IGF-I (B-chain mutant), in which the first 16 amino acids of hIGF-I were replaced with the first 17 amino acids of the B-chain of insulin, has greater than 1,000-, 100-, and 2-fold reduced potency for human serum binding proteins, the rat liver type 2 IGF receptor, and the human placental type 1 IGF receptor, respectively. The B-chain mutant also has 4-fold increased affinity for the human placental insulin receptor. [Gln3,Ala4]IGF-I has 4-fold reduced affinity for human serum binding proteins, but is equipotent to hIGF-I at the types 1 and 2 IGF and insulin receptors. [Tyr15,Leu16]IGF-I has 4-fold reduced affinity for human serum binding proteins and 10-fold increased affinity for the insulin receptor. This peptide is also equipotent to hIGF-I at the types 1 and 2 IGF receptors. The peptide in which these four-point mutations are combined, [Gln3,Ala4,Tyr15,Leu16]IGF-I, has 600-fold reduced affinity for the serum binding proteins. This peptide has 10-fold increased potency for the insulin receptor, but is equipotent to hIGF-I at the types 1 and 2 IGF receptors. All four of these mutants stimulate DNA synthesis in the rat vascular smooth muscle cell line A10 with potencies reflecting their potency at the type 1 IGF receptor. These studies identify some of the domains of hIGF-I which are responsible for maintaining high affinity binding with the serum binding protein and the type 2 IGF receptor. In addition, these peptides will be useful in defining the role of the type 2 IGF receptor and serum binding proteins in the physiological actions of hIGF-I.     

The osmotic/calcium stress theory of brain damage: Are free radicals involved?

This overview presents data showing that glucose use increases and that excitatory amino acids (i.e., glutamate, aspartate), taurine and ascorbate increase in the extracellular fluid during seizures. During the cellular hyperactive state taurine appears to serve as an osmoregulator and ascorbate may serve as either an antioxidant or as a pro-oxidant. Finally, a unifying hypothesis is given for seizure-induced brain damage. This unifying hypothesis states that during seizures there is a release of excitatory amino acids which act on glutamatergic receptors, increasing neuronal activity and thereby increasing glucose use. This hyperactivity of cells causes an influx, of calcium (i.e. calcium stress) and water movements (i.e., osmotic stress) into the cells that culminate in brain damage mediated by reactive oxygen species.Special issue dedicated to Dr. Frederick E. Samson     

Post-operative analgesia following thoracotomy in the dog: an evaluation of the effects of bupivacaine intercostal nerve block and nalbuphine on respiratory function.

Pain following thoracotomy reduces pulmonary ventilation in man and a similar effect is believed to occur in animals. The effects of two analgesic regimens on arterial blood gas parameters were studied in dogs following thoracotomy. Post-Operative analgesia was provided with intermittent nalbuphine, either alone or in combination with an intercostal nerve block using bupivacaine. Arterial blood gas analysis was carried out at 4, 8 and 16 h post-operatively, both before the administration of nalbuphine and again 30 min later. Animals which received nalbuphine alone had a significant rise in arterial oxygenation following administration of this analgesic. This effect was not observed at 4 and 8 h post-operatively in dogs which had an intercostal block with bupivacaine, but was seen at 16 h post-operatively when it could be anticipated that the effects of bupivacaine would have waned. These results suggest that intercostal block with bupivacaine can provide analgesia for over 8 h, and that the duration of action of nalbuphine in controlling post-operative pain in the dog is probably less than 4 h.     

Hematology, serum chemistry values, and rectal temperatures of adult greater galagos (Galago garnetti and G. crassicaudatus)

Hematological and serum chemistry values, as well as rectal temperatures, were obtained from greater galagos (Galago garnettii and G. crassicaudatus), in order to establish normative values. No species or sex differences were found for four hematological parameters and 15 serum chemistry parameters. Species differences were seen in phosphate, magnesium, cholesterol, alkaline phosphate, G-glutamyl transferase, mean corpuscular volume and leucocyte, neutrophil, and lymphocyte number. Significant sex differences were observed in glucose, hemoglobin, and hematocrit values. Species and sex differences were seen in chloride and erythrocyte number.     

Prediction of femoral impact forces in falls on the hip.

A major determinant of the risk of hip fracture in a fall from standing height is the force applied to the femur at impact. This force is determined by the impact velocity of the hip and the effective mass, stiffness, and damping of the body at the moment of contact. We have developed a simple experiment (the pelvis release experiment) to measure the effective stiffness and damping of the body when a step change in force is applied to the lateral aspect of the hip. Results from pelvis release experiments with 14 human subjects suggest that both increased soft tissue thickness over the hip and impacting the ground in a relaxed state can decrease the effective stiffness of the body, and subsequently reduce peak impact forces. Comparison between our fall impact force predictions and in-vitro measures of femoral fracture strength suggest that any fall from standing height producing direct, lateral impact on the greater trochanter can fracture the elderly hip.     

Fracture prediction for the proximal femur using finite element models: Part II--Nonlinear analysis.

In Part I we reported the results of linear finite element models of the proximal femur generated using geometric and constitutive data collected with quantitative computed tomography. These models demonstrated excellent agreement with in vitro studies when used to predict ultimate failure loads. In Part II, we report our extension of those finite element models to include nonlinear behavior of the trabecular and cortical bone. A highly nonlinear material law, originally designed for representing concrete, was used for trabecular bone, while a bilinear material law was used for cortical bone. We found excellent agreement between the model predictions and in vitro fracture data for both the onset of bone yielding and bone fracture. For bone yielding, the model predictions were within 2 percent for a load which simulated one-legged stance and 1 percent for a load which simulated a fall. For bone fracture, the model predictions were within 1 percent and 17 percent, respectively. The models also demonstrated different fracture mechanisms for the two different loading configurations. For one-legged stance, failure within the primary compressive trabeculae at the subcapital region occurred first, leading to load transfer and, ultimately, failure of the surrounding cortical shell. However, for a fall, failure of the cortical and trabecular bone occurred simultaneously within the intertrochanteric region. These results support our previous findings that the strength of the subcapital region is primarily due to trabecular bone whereas the strength of the intertrochanteric region is primarily due to cortical bone.     

Isolation, identification and synthesis of locustamyoinhibiting peptide (LOM-MIP), a novel biologically active neuropeptide from Locusta migratoria.

A novel peptide termed locustamyoinhibiting peptide (LOM-MIP) was isolated from brain-corpora cardiaca-corpora allata-suboesophageal ganglion extracts of the locust, Locusta migratoria. The primary structure of this nonapeptide has been determined Ala-Trp-Gln-Asp-Leu-Asn-Ala-Gly-Trp-NH2. LOM-MIP suppresses the spontaneous contractions of the hindgut and oviduct of Locusta migratoria and of the hindgut of Leucophaea maderae. This novel peptide is, however, structurally different from leucomyosuppressin, a hindgut suppressing peptide isolated from Leucophaea maderae heads. LOM-MIP has a Gly-TrpNH2 carboxy-terminal in common with APGWamide, a penis retractor muscle inhibiting peptide isolated from the snail, Lymnea stagnalis. In addition, it shows carboxy-terminal sequence similarities with locust AKH II which ends in AGWamide. No sequence similarities were found with other vertebrate or invertebrate peptides. Synthetic LOM-MIP showed biological as well as chemical characteristics indistinguishable from those of native LOM-MIP.