Viscoelastic response of intervertebral disks at audiofrequencies

The viscoelastic responses of intervertebral disks taken from the cervical regions of the spinal columns of several adult, male, mongrel dogs have been determined. The results are presented in terms of a mean complex shear compliance,J _d*=J′ _d ?iJ″ _d , for the disk structures when these are subjected to small-amplitude audiofrequency vibrations (25–5000 Hz) while surrounded by normal salt solution, both at room temperatures and at 98·6°F (37.0°C) (in vitro). Values of the general compliance levels decrease with time after sacrifice, and an abrupt transition in the 100-Hz compliance-time curves at 5·5 hours after death is attributed to the completion of rigor mortis (at room temperature). Comparisons of the broad compliance-frequency disk spectra with those of five synthetic polymeric materials, including a silicone rubber, are presented and suggestions for materials suitable to be used in disk prosthesis are made. Such materials must have values of both elastic compliance (J′) and viscous compliance (J″) which are close to the corresponding living disk compliances. A brief discussion of the characteristic sharp resonance dispersions or fine structure observed in the disk spectra is also presented along with suggestions for future measurements. Finally, the idea is advanced that a composite synthetic structure with a stiff, outer ring of low compliance and a very compliant inner core might most satisfactorily mimic the viscoelastic behaviour of a normal intervertebral diskin vivo.     

Genetic segregation of spontaneous erosive arthritis and generalized autoimmune disease in the BXD2 recombinant inbred strain of mice

The BXD2 strain of mice is one of approximately 80 BXD recombinant inbred (RI) mouse strains derived from an intercross between C57BL/6J (B6) and DBA/2J (D2) strains. We have discovered that adult BXD2 mice spontaneously develop generalized autoimmune disease, including glomerulonephritis (GN), increased serum titres of rheumatoid factor (RF) and anti-DNA antibody, and a spontaneous erosive arthritis characterized by mononuclear cell infiltration, synovial hyperplasia, and bone and cartilage erosion. The features of lupus and arthritis developed by the BXD2 mice segregate in F2 mice generated by crossing BXD2 mice with the parental B6 and D2 strains. Genetic linkage analysis of the serum levels of anti-DNA and RF by using the BXD RI strains shows that the serum titers of anti-DNA and RF were influenced by a genetic locus on mouse chromosome (Chr) 2 near the marker D2Mit412 (78 cm, 163 Mb) and on Chr 4 near D4Mit146 (53.6 cm, 109 Mb), respectively. Both loci are close to the B-cell hyperactivity, lupus or GN susceptibility loci that have been identified previously. The results of our study suggest that the BXD2 strain of mice is a novel model for complex autoimmune disease that will be useful in identifying the mechanisms critical for the immunopathogenesis and genetic segregation of lupus and erosive arthritis.     

A comparison of the bronchodilator activity of Sch 1000 and salbutamol.

The effects of the beta 2-adrenergic agonist, salbutamol, 200 mug, and the cholinergic antagonist, Sch 1000, 40 mug, have been compared in 25 asthmatic patients using a single dose, double-blind, crossover trial design. Salbutamol aerosol produces a greater degree of bronchodilatation than Sch 1000 aerosol during the initial three hours following drug administration. There is no significant difference in the bronchodilator effects of the two drugs in the interval four to eight hours after drug administration. Nonatopic patients showed less difference in bronchodilator response to each of the two drugs than atopic patients. Neither drug showed any significant adverse effect on blood pressure, pulse rate, or electrocardiogram. In six asthmatic patients the effect of the combination of salbutamol, 200 mug, and Sch 1000, 40 mug, was evaluated. The combination produced a longer duration of bronchodilatation than either drug alone when compared to placebo.     

Comprehensive ribotyping scheme for heat-stable serotypes of Campylobacter jejuni.

Strains from diverse sources belonging to all 47 heat-stable Penner serotypes of Campylobacter jejuni were examined for polymorphism around the 16S rRNA genes. Penner serotype reference strains and a group of nonserotypeable isolates were included in the study. Complete typeability was obtained; 30 distinct PstI and 42 HaeIII polymorphisms were found. Three bands were detected in almost all strains with these enzymes, confirming that three copies of the 16S rRNA gene are typical for C.jejuni. By combination of the two enzyme polymorphisms, 77 16S ribotypes were defined among the 261 strains analyzed. With two exceptions, no specific association was observed between these ribotypes and heat-stable serotypes. Nine serotypes were homogeneous with respect to the 16S ribotype. Most nonserotypeable strains belonged to ribotypes defined elsewhere in the study. The 16S ribotypes of C.jejuni described here were not found in strains of Campylobacter coli, and vice versa.     

Alcohol use following liver transplantation: a comparison of follow-up methods

Alcoholic cirrhosis is one of the most common indications for liver transplantation. Previous researchers have studied rates of return to drinking following transplantation, however, few have employed prospective measures of alcohol use. The authors prospectively studied the alcohol use of patients transplanted for alcoholic liver disease. The authors improved the accuracy of monitoring alcohol use by using various methods for tracking patient's alcohol consumption, and we report on the time to first alcohol use after transplantation comparing these different methods. The authors found that alcohol use can occur very early after transplantation, even within the first 3 months posttransplant. Thirty-eight percent of the patients consumed any alcohol after transplantation. The clinical interviews by the psychiatrist were the most successful method for identifying posttransplant alcohol use. Posttransplant alcohol use was significantly associated with prior nonalcohol substance use (P < 0.025), family history of alcoholism in a first-degree relative (P < 0.025), and prior alcohol rehabilitation experience (P < 0.05) but not with a prior psychiatric history or less than 6 months of pretransplant sobriety. The authors indicate that prospective monitoring, using a combination of methods, is the most accurate approach to identify alcohol consumption. With this type of accuracy, risk factors can be identified and alcohol use can be compared with alcohol-related morbidity posttransplant.     

Characterization of a major neutralization domain of Ross river virus using anti-viral and anti-peptide antibodies.

The E2 glycoprotein of the alphavirus Ross River virus (RRV) contains three defined neutralization epitopes (a, b1 and b2) with determinants located between amino acids 216 and 251 in the linear sequence (Vrati et al., 1988, Virology 162, 346-353). The antigenic structure of this region has been examined using hyperimmune mouse antiserum against RRV and antiserum against four synthetic peptides representing linear amino acid sequences in the neutralization region of E2. In plaque reduction neutralization tests using hyperimmune antiserum to RRV, an RRV mutant altered at all three neutralization epitopes was markedly more resistant than the parental virus; variants altered at single epitopes could not be distinguished in these tests. Sera from mice immunized with synthetic RRV E2 peptides conjugated to keyhole limpet haemocyanin reacted, in a direct ELISA, with the specific region of RRV represented by the peptide. The same sera did not neutralize or immunoprecipitate RRV in solution or bind to RRV in a capture ELISA. The RRV peptides did not prime mice to react to a subimmunogenic dose of RRV; they did not bind monoclonal or polyclonal antibodies to RRV. We conclude that a significant proportion of the neutralizing antibody response in mice is elicited by epitopes a, b1, and b2 of RRV E2 and that the sites to which neutralizing antibodies bind are formed by complex folding.     

Fos-like immunoreactivity in brain regions of domestic rams following exposure to rams or ewes

Limbic and basal forebrain-hypothalamic regions from male sheep differing in sexual performance were quantified for fos-like immunoreactivity. Rams classified as high-sexually performing (HP), low-sexually performing (LP), and male-oriented (MO) received noncontact sensory stimulation from either ewes in estrus (HP, n=5; LP, n=4; MO, n=4) or other males (HP, n=5; LP, n=4; MO, n=5) for a 4-h period on each of 3 consecutive days. Following exposure to stimulus animals on the third day, rams were euthanized and their brains were perfused with a 1% paraformaldehyde/1.5% glutaraldehyde solution and sections were analyzed for fos-like immunoreactivity. Brain regions analyzed were the medial amygdala (meAMY), medial preoptic area (mPOA), bed nucleus of the stria terminalis (BNST), and ventromedial hypothalamic nucleus (VMH). Fos-like immunoreactivity differed between groups in the mPOA and BNST but not in the meAMY or VMH. LP rams exposed to estrous ewes had more (P<.05) neurons staining positive for fos and fos-related antigens (FRA) in the mPOA and BNST than LP rams exposed to other rams or MO rams exposed to either estrous ewes or other rams. Numbers of neurons staining positive for FRA in the mPOA and BNST of LP rams exposed to estrous ewes, however, were not different (P>.05) from HP rams exposed to either estrous ewes or other rams. The similar fos-like immunoreactivity in areas important for the display of sexual behavior in HP and LP rams may reflect similar sensory input in these two groups of rams; however, LP rams, in contrast to HP rams, do not appear to respond similarly to the same sensory stimulus.