Use of expected progeny differences for marbling in beef: II. Carcass and palatability traits

A 2-yr study was conducted to determine the effect of EPD for marbling on marbling score, palatability traits, and carcass fatness in beef. Steer (n = 122) and heifer (n = 123) carcasses were obtained by mating Angus bulls having a high ( > .4) or low ( < -.16) EPD for marbling to MARC II cows (1/4 Angus, 1/4 Hereford, 1/4 Simmental, and 1/4 Gelbvieh). Carcass traits, composition of primals, quarters, and sides, palatability, and shear force data were obtained and adjusted to the mean number of days on feed, equal marbling score (Small50), fat thickness (1.0 cm), and carcass weight (318 kg) end points. Steer carcasses from the high marbling EPD group, adjusted to the mean number of days on feed, had significantly more marbling (P < .01) and less subcutaneous fat in the side and the hindquarter (P < .10) than their low marbling EPD counterparts. Adjusting steers to Small50 marbling produced smaller longissimus muscle area (by 5 cm2), less fat thickness (1.15 vs 1.28 cm), and lighter side weights (306 vs 333 kg) for high marbling vs low marbling EPD groups, indicating a faster rate of marbling deposition. Similar relationships of a greater magnitude were found for heifers, perhaps because the heifers were older than the steers at slaughter. No differences in taste panel ratings or shear force values were noted among steer carcasses. Heifer carcasses from the high marbling EPD group had better (P < .05) ratings for juiciness, muscle fiber tenderness, and overall tenderness than the low marbling EPD group heifers. These results indicate that it is possible, using existing genetic resources, to maintain marbling score and decrease fat in other depots of the carcass without compromising palatability.     

Enhanced activity of an antisense oligonucleotide targeting murine protein kinase C-alpha by the incorporation of 2'-O-propyl modifications

We have previously described the characterization of a 20mer phosphorothioate oligodeoxynucleotide (ISIS 4189) which inhibits murine protein kinase C-alpha (PKC-alpha) gene expression, both in vitro and in vivo. In an effort to increase the antisense activity of this oligonucleotide, 2'-O-propyl modifications have been incorporated into the 5'- and 3'-ends of the oligonucleotide, with the eight central bases left as phosphorothioate oligodeoxynucleotides. Hybridization analysis demonstrated that these modifications increased affinity by approximately 8 and 6 degrees C per oligonucleotide for the phosphodiester (ISIS 7815) and phosphorothioate (ISIS 7817) respectively when hybridized to an RNA complement. In addition, 2'-O-propyl incorporation greatly enhanced the nuclease resistance of the oligonucleotides to snake venom phosphodiesterase or intracellular nucleases in vivo. The increase in affinity and nuclease stability of ISIS 7817 resulted in a 5-fold increase in the ability of the oligonucleotide to inhibit PKC-alpha gene expression in murine C127 cells, as compared with the parent phosphorothioate oligodeoxynucleotide. Thus an RNase H-dependent phosphorothioate oligodeoxynucleotide can be modified as a 2'-O-propyl 'chimeric' oligonucleotide to provide a significant increase in antisense activity in cell culture.     

A new instrument to assess the long-term quality of life effects from migraine: development and psychometric testing of the MSQOL

Quality of life is important to persons experiencing migraine. This study discusses the development of a migraine-specific quality-of-life measure (MSQOL). Participants, who included migraineurs from both tertiary care centers and the community, were screened using the International Headache Society migraine criteria prior to enrollment. Internal consistency of the MSQOL was high (alpha 0.92). Reproducibility over an average of 24 days was high (intraclass correlation 0.90). Construct validity was determined by convergent validity and known groups validity. The MSQOL was compared to two other frequently used health status questionnaires; results indicate that the MSQOL more closely resembles well-being than functional status. Results also indicate that migraineurs with more symptoms, medical appointments per year to treat migraines, and migraine episodes per year have a significantly worse quality of life. The MSQOL proved valid and reliable as a self-administered measure and will be a useful tool in clinical migraine research. The information gained from its use in the clinical environment should provide important additional information about the impact of migraine on quality of life and the potential benefits of therapeutic interventions.     

Hemin: levels in experimental subarachnoid hematoma and effects on dissociated vascular smooth-muscle cells

Although hemin is known to exert toxic effects on a variety of cell types, its possible participation in the genesis of cerebral vasospasm has received little attention. The authors measured the concentration of hemin in experimental subarachnoid clot and studied its effects on the morphology and 45Ca++ uptake of vascular smooth-muscle cells dissociated from canine carotid artery. Craniectomies were performed in five dogs under general anesthesia, and 3 to 5 ml of autologous whole blood was deposited in the supraclinoid subarachnoid compartment. The concentration of hemin recovered by Folch extraction from clotted material removed 7 days after surgery was 390 +/- 247 microM (mean +/- standard error of the mean). Mean vascular smooth-muscle cell length after 40 minutes of exposure to 50 microM hemin was 37.3 +/- 1.2 microns (control 51.6 +/- 1.6 microns) (p < 0.01). The mean percent permeation of 45Ca++, measured by a dual label technique, of cells exposed to hemin was 200.9% +/- 23% (control 102.9% +/- 4.3%) (p < 0.01). These findings indicate that hemin accrues in subarachnoid hematoma, that it exerts a constrictive effect on vascular smooth-muscle cells, and that this effect is associated with an increased uptake of Ca++. This study demonstrates that hemin should be included in the list of potential agents that participate in the development of cerebral vasospasm.     

Lipids and lipoproteins in a group of patients with ischemic cerebrovascular disease

OBJECTIVE: To study the blood levels of a group of lipids and lipoproteins in patients with ischemic cerebrovascular disease which was not secondary to cardiac embolic disease. PATIENTS AND METHODS: We assessed 40 patients of an average age of 64.5 years. Of these, 26 had cerebral infarcts due to disease of the great vessels and 14 had lacunar infarcts. Forty persons with no cerebrovascular disease were used as controls. We excluded patients diagnosed as having renal failure, liver, hematological, neoplastic and acute febrile disorders. Plasma was analyzed for total cholesterol, triglycerides, lipoproteins (a), HDL, LDL, VLDL and apoprotein B between 3 weeks and 6 months after the initial stroke. RESULTS AND CONCLUSIONS: Levels of triglycerides and of lipoprotein (a) were significantly greater in patients than in controls. We found no differences between the levels of total cholesterol, HDL, LDL, VLDL in the three groups studied. However, apoprotein B was greater in the controls than in the patients. There were no significant differences between the groups with lacunar ictus and those with infarcts secondary to disease of the great vessels.     

Effects of localized pontine lesions on auditory brain-stem evoked potentials and binaural processing in humans

Potassium channels are involved in the control of neuronal excitability by fixing the membrane potential, shaping the action potential, and setting firing rates. Recently, attention has been focused on identifying the factors influencing excitability in second-order auditory and vestibular neurons. Located in the brainstem, second-order auditory and vestibular neurons are sites for convergence of inputs from first-order auditory or vestibular ganglionic cells with other sensory systems and also motor areas. Typically, second-order auditory neurons exhibit two distinct firing patterns in response to depolarization: tonic, with a repetitive firing of action potentials, and phasic, characterized by only one or a few action potentials. In contrast, all mature vestibular second-order neurons fire tonically on depolarization. Already, certain fundamental roles have emerged for potassium currents in these neurons. In mature auditory and vestibular neurons, I(K), the delayed rectifier, is required for the fast repolarization of action potentials. In tonically firing auditory neurons, I(A), the transient outward rectifier, defines the discharge pattern. I(DS), a delayed rectifier-like current distinguished by its low threshold of activation, is found in phasically firing auditory and some developing vestibular neurons where it limits firing to one or a few spikes, and also may contribute to forming short-duration excitatory postsynaptic potential (EPSPs). Also, I(DS) sets the threshold for action potential generation rather high, which may prevent spontaneous discharge in phasically firing cells. During development, there is a gradual acquisition and loss of some potassium conductances, suggesting developmental regulation. As there are similarities in membrane properties of second-order auditory and vestibular neurons, investigations on firing pattern and its underlying mechanisms in one system should help to uncover fundamental properties of the other.