Esculin hydrolysis by Streptococcus dysgalactiae

In a mastitis control program based on eradication of intramammary infection, it is important to differentiate streptococci. According to earlier reports, Streptococcus dysgalactiae was unable to hydrolyze esculin. Preliminary data from the present study indicated that under optimal conditions, some strains of S dysgalactiae were capable of esculin hydrolysis. In a study of 45 strains of S dysgalactiae, 55.5% were able to hydrolyze esculin. In the past, these organisms would probably have been identified as Streptococcus uberis. Streptococcus dysgalactiae is more sensitive to antibiotics than S uberis, and the infection is easier to eradicate from infected glands.     

Vitamin D metabolite-binding proteins in human tissue

Serum and post-microsomal supernatants of human lymphocyte, erythrocyte, skeletal muscle and parathyroid adenoma homogenates were examined for specific binding of 25-hydroxycholecalciferol (25-OHD3) and 1, 25-dihydroxycholecalciferol (1,25-(OH)2D3). Muscle, lymphocytes and parathyroid adenomata extracts contained a 6-S 25-OHD3-binding protein which was not found in erythrocyte extracts, and which was distinct from the smaller serum transport alpha-globulin. A cathodal, 1, 25-(OH)2D3-binding protein, which sedimented at 3-4 S was also detected in parathyroid tissue. These observations suggest the possibility of direct physiologic interaction between vitamin D metabolites and nucleated human tissues other than intestine and bone.     

Fractionation of aqueous ethanolic extracts from bread

Column chromatography of an aqueous ethanolic extract from bread crust on alkylated Sephadex (LH-20) partly separated it into five coloured fractions. Further partial separation of two of these fractions was achieved by chromatography on Sephadex G-15 and silica gel columns, and by thin-layer chromatography. Maltose, glucose and fructose were determined in crust and crumb extracts by quantitative paper chromatography.     

PVC melt rheology III: The effect of order and molecular weight on the shear rate dependence

The effect of polymerization temperature on the melt flow behavior of PVC of varying molecular weights has been studied over a wide shear rate range. For the same molecular weight, higher melt viscosities are observed for polymers prepared at lower temperatures. The shear rate dependence of the viscosity vs molecular weight plot is shown to be nonlinear over the shear rates examined. The inability to achieve a limiting zero-shear viscosity is discussed.     

Sensitivity to interaural time differences in the medial superior olive of a small mammal, the Mexican free-tailed bat

Neurons in the medial superior olive (MSO) are thought to encode interaural time differences (ITDs), the main binaural cues used for localizing low-frequency sounds in the horizontal plane. The underlying mechanism is supposed to rely on a coincidence of excitatory inputs from the two ears that are phase-locked to either the stimulus frequency or the stimulus envelope. Extracellular recordings from MSO neurons in several mammals conform with this theory. However, there are two aspects that remain puzzling. The first concerns the role of the MSO in small mammals that have relatively poor low-frequency hearing and whose heads generate only very small ITDs. The second puzzling aspect of the scenario concerns the role of the prominent binaural inhibitory inputs to MSO neurons. We examined these two unresolved issues by recording from MSO cells in the Mexican free-tailed bat. Using sinusoidally amplitude-modulated tones, we found that the ITD sensitivities of many MSO cells in the bat were remarkably similar to those reported for larger mammals. Our data also indicate an important role for inhibition in sharpening ITD sensitivity and increasing the dynamic range of ITD functions. A simple model of ITD coding based on the timing of multiple inputs is proposed. Additionally, our data suggest that ITD coding is a by-product of a neuronal circuit that processes the temporal structure of sounds. Because of the free-tailed bat's small head size, ITD coding is most likely not the major function of the MSO in this small mammal and probably other small mammals.     

Comparison of tension band wiring and lateral mass plating for subaxial posterior cervical fusion

BACKGROUND: Two instrumentation methods for subaxial posterior cervical fusion are compared in terms of efficacy, morbidity, and significant cost-related variables. METHOD: Thirty-four patients with tension band wiring and 14 patients with lateral mass plating are retrospectively compared in a single surgeon's experience between 1989 and early 1995. RESULTS: Both groups were similar in regard to operative indication (about 40% trauma, 30% degenerative changes in each group), postoperative immobilization (hard collar only used in 82% of patients wired and 79% of patients plated), and number of levels fused (mean, 1.7 in each group). Mean follow-up is 23 months for wiring and 35 months for plating. Pseudoarthrodesis occurred in one patient undergoing wiring and in none of the patients plated. Both methods resulted in complications (7 in 34 cases of wiring, 4 in 14 cases of plating), but no patient experienced neurologic decline. Statistically significant differences between the two groups were found for estimated blood loss, operating room time, and hardware cost, but not for postoperative orthosis or length of stay. CONCLUSION: In some instances when subaxial posterior fusion is performed, tension band wiring may be more cost-efficient. Tension band wiring and lateral mass plating seem to have comparable efficacy and morbidity, but the indications for each technique differ.