Cross-sectional study of osteopenia with quantitative MR imaging and bone densitometry.

PURPOSE: To evaluation the cancellous bone-induced intravoxel spin dephasing rate (R2') and its relationship to bone mineral density and marrow fat and to examine these parameters as predictors of vertebral fracture status. MATERIALS AND METHODS: R2' and R2, the rate constants for reversible and irreversible spin dephasing, and marrow fat fraction were measured in the lumbar vertebrae and proximal femur. One hundred thirty-nine subjects (mean age, 62.4 years +/- 11.4 [SD]; 33 men, 106 women) had spinal dual-energy x-ray absorptiometric bone mineral density (BMD) T scores ranging from +3 to -5. R2', BMD, and bone marrow composition as determinants of vertebral fracture status were examined. RESULTS: Strongest single predictors of fracture status for BMD and R2' were the Ward triangle (r(2) = 0.48) and trochanter (r(2) = 0.37), respectively. Combined, the two parameters and sites increased fracture prediction (r(2) = 0. 62), whereas the combination of multiple BMD sites did not. Multivariate regression involving marrow fat fraction further improved fracture status prediction. R2' was correlated with BMD at all sites, although slopes differed by a factor of up to 2.5, which reflected differences in trabecular orientation relative to the static field. R2, the true transverse relaxation rate, was negatively correlated with marrow fat fraction. A non-age-related increase in marrow fat fraction in osteoporosis parallels earlier findings in animal models. CONCLUSION: Cancellous bone marrow R2' measured in the proximal femur provides information, which, with BMD, improves prediction of vertebral fracture status.

Palatability of wethers fed an 80% barley diet processed at different ages and of yearling wethers grazed on native range.

Seasonal availability of lamb in the Western United States contributes to a large fluctuation in lamb supply and value. However, alternatives to fall marketing may not be practical unless palatability traits are acceptable. A 3-yr study was conducted to investigate 1) the effects of slaughter age (7 to 8; 10 to 11; or 14 to 15 mo) on carcass and palatability characteristics of wethers fed an 80% barley diet (Exp. 1); and 2) the effects of finishing on range or on an 80% barley diet on carcass and palatability traits of 14- to 15-mo-old wethers (Exp. 2). In Exp. 1, no differences (P = .27) were detected in flavor intensity or longissimus muscle area among slaughter age groups, but fat depth was greater (P < .05) for 7- to 8-mo-old wethers than for 10- to 11- or 14- to 15-mo-old wethers. Year x slaughter age interactions were detected (P < .10) for hot carcass weight, Warner-Bratzler shear value, body wall thickness, and percentage kidney fat. Hot carcass weight was greater (P < .05) for 14- to 15-mo-old wethers than for both groups of younger wethers in yr 1, did not differ (P = .53) among slaughter ages in yr 2, and was greater (P < .05) for 10- to 11- than for 14- to 15-mo-old wethers in yr 3. Warner-Bratzler shear values did not differ (P > .10) among slaughter ages in yr 1 and 3, but shear values for 14- to 15-mo-old wethers were greater (P < .05) than for both younger slaughter age groups in yr 2. Percentage kidney fat was lower (P < .05) for 14- to 15- than for 7- to 8-mo-old wethers in all years. In Exp. 2, flavor intensity of the meat did not differ (P = .35) between finishing systems, but longissimus muscle area was greater (P = .02) for range-finished wethers than for wethers fed an 80% barley diet. Year x finishing treatment interactions were detected (P < .10) for shear values, body wall thickness, percentage kidney fat, and fat depth. Shear values were greater (P = .10) for range-finished wethers than for wethers fed an 80% barley diet in yr 1, but did not differ (P > .55) in yr 2 and 3. Body wall and fat measurements were greater (P < .10) for wethers fed an 80% barley diet than for range-finished wethers in all years except yr 3, when fat depth did not differ (P = .47). Overall, slaughtering wethers fed an 80% barley diet or range-finished wethers at older ages produced acceptable carcasses with desirable meat palatability traits.

Measurement of R'2 in the presence of multiple spectral components using reference spectrum deconvolution.

A method is described for measuring R'2, the RF reversible contribution to the effective transverse relaxation rate in yellow trabecular marrow, as a means to evaluate trabecular bone structure and density. The method exploits the similarity in spectral composition of the marrow and fat in subcutaneous tissue. Under these conditions the gradient echo envelope of the marrow signal can be regarded as a convolution of a function describing the bone marrow intravoxel line broadening (R'2) with a function expressing chemical shift modulation, which is obtained from the echo envelope of the subcutaneous fat signal in a reference region. Simple division of each of a series of echoes by the reference signal is shown to afford a smooth decay which can be fitted to a model to extract R'2. The method has been evaluated in the upper femur of test subjects and a strong correlation of the thus derived R'2 values with those obtained by the GESFIDE technique is demonstrated. The close correspondence in spectral composition of proximal femur marrow and subcutaneous fat is further illustrated by means of localized spectroscopy. The major potential error source is global inhomogeneity in the reference region which can lead to an underestimation of the demodulation-derived R'2.

Magnetic susceptibility measurement of insoluble solids by NMR: magnetic susceptibility of bone.

Measurements of the volume magnetic susceptibility of solids using the classical Gouy balance approach are hampered by variations in apparent density of the packed powder. In this paper a quantitative NMR measurement of the volume magnetic susceptibility of powdered solids is described and the volume susceptibility of bone is reported. The technique is based on the measurement of changes in incremental linewidth (1/pi T2') induced in a marker fluid whose susceptibility can be predictably modified by changing the composition, such as by addition of a soluble diamagnetic compound. The spectroscopic linewidth of the marker fluid is determined by the susceptibility difference between the fluid and the suspended solid. Changes in the linewidth are accompanied by bulk magnetic susceptibility induced frequency shifts in the fluid resonance. Correlating the two dependencies allows measurement of the absolute volume susceptibility of the solid. The susceptibility of bovine rib bone was found to be -0.9 +/- 0.02 x -10(-6) (CGS) confirming previous estimates which suggested bone to be more diamagnetic than the marrow constituents. Knowledge of the susceptibility of bone is relevant in view of the growing interest in MRI osteodensitometric techniques.

The effects of amount of whole barley, barley bulk density, and form of roughage on feedlot lamb performance, carcass characteristics, and digesta kinetics.

We conducted two feedlot trials and one metabolism trial to evaluate the effect of barley level, barley bulk density, and physical form of roughage on lamb growth performance and digesta kinetics. Level of whole barley (50, 70, 90%) and type of roughage (chopped or pelleted alfalfa) were evaluated in Trial 1 (50 d period). Trial 2 (50 d) evaluated barley bulk density (heavy = 671 and light = 607 kg/m3), form of roughage (pelleted or chopped alfalfa), and level of barley (80 or 40%). The influence of treatments used in Trial 2 on digesta kinetics was evaluated in Trial 3. Gain:feed increased and DMI decreased (P < .10) linearly with increasing level of barley, and ADG and DMI were greater (P < . 10) for lambs fed pelleted vs chopped alfalfa in Trial 1. The 70% barley diet produced the highest yield grade and kidney-pelvic fat and the lowest leg score among barley levels (P < .10). Lambs fed pelleted alfalfa had heavier carcasses and a thicker body wall than lambs fed chopped alfalfa (P < .02). In Trial 2, DMI was less and gain:feed greater (P < .01) for lambs fed the heavy barley than for lambs fed the light barley and for the 80% barley diet compared to the 40% barley diet. Lambs fed pelleted alfalfa had greater dressing percentages than lambs fed chopped alfalfa. Backfat and body wall thickness were greater (P < .10) for lambs fed the 80% barley diet than for those fed the 40% barley diet. In Trial 3, retention time of barley was greater (P < .10) for lambs fed light rather than heavy barley, and retention time of alfalfa was greater (P < .10) for lambs fed chopped compared with pelleted alfalfa. Acetate:propionate ratio was greater (P < .10) for lambs fed light vs heavy barley and lambs fed the 40 vs 80% barley diets. Ruminal pH was lower (P = .05) and in situ barley digestion greater (P = .03) over time in lambs fed the 80% barley diet than in lambs fed the 40% barley diet. Feedlot lamb ADG was not always greatest with high levels of barley; however, gain:feed improved at the higher barley levels. The higher barley levels seemed to result in fatter lambs.

Refractive index of NH(4)Cl-H2O as a function of wavelength: the effect of temperature and concentration.

The refractive index of NH(4)Cl-H(2)O solutions has been measured over a wavelength range from 496.5 to 690 nm. The NH(4)Cl concentration was varied from 15 to 30 wt. % over a temperature range from 10 to 35 °C. We obtained mathematical equations relating the refractive index to wavelength, temperature, and concentration using the least-squares method. A knowledge of these properties is important for analyzing and modeling the dendritic growth of this system.

A strategy for the identification of candidate genes for alcohol-related phenotypes and other human disorders using rapid polymerase chain reaction mapping of gene-based sequence-tagged sites.

We describe a method for the rapid identification and mapping of human genes, including those possibly contributing to disease and alcohol-related phenotypes. New human genes are identified from cDNA libraries through single-pass sequencing into the 3' untranslated (3'UT) regions of human brain cDNAs. Primers derived from the 3'UT region sequences [representing gene-based, sequence-tagged sites (STSs)] are used for polymerase chain reaction (PCR) analyses of the CEPH megabase insert yeast artificial chromosome (YAC) DNA pools. With this approach, approximately 18,000 megabase YACs can be screened and a single YAC identified using only 52 PCR reactions. The YAC localization in conjunction with other mapping techniques, such as PCR mapping to human chromosomes using somatic cell hybrids, allows identification of chromosomal band locations. In this manner, each gene can be associated with its own STS, which in turn specifies both a corresponding genomic clone and specific location in the genome. These locations can be compared with the purported locations of disease genes. The locations of the STSs can also be compared with those of Quantitative Trait Loci implicated for quantitative traits (e.g., alcohol-related phenotypes) on the basis of synteny between the mouse and human genes. Using this strategy, we found candidates for 78 human disease/syndrome genes among the first 220 genes mapped.

Gene-based sequence-tagged-sites (STSs) as the basis for a human gene map.

Using our data set of 3,143 single pass sequences from human brain cDNA libraries, we have developed a strategy in which gene-based sequence-tagged-sites (STSs), derived from 3'untranslated regions of human cDNAs, are rapidly assigned to megabase-insert yeast artificial chromosomes and somatic cell hybrids to generate regional gene mapping data. Employing this approach, we have mapped 318 cDNAs, representing 308 human genes. Ninety-two of these mapped to regions implicated in human genetic diseases, identifying them as candidate genes. Extension of this strategy has the potential to result in virtually every human gene having, at its 3' end, its own associated STS, with each STS in turn specifying both a corresponding genomic clone and a specific regional location in the genome.

Clinical correlates of anaerobic bacteriology in peritonitis.

Recent surgical reports indicate that for patients with secondary bacterial peritonitis, surgeons do not routinely use the identification of the bacterial pathogens and determination of their antimicrobial susceptibilities in choosing antimicrobial therapy. Further, some surgeons advocate abandoning the routine practice of obtaining culture specimens from patients with complicated appendicitis, because the data from the clinical laboratory have not been found to have an impact on postoperative care. We review the rationale for continued surveillance of and implementation of bacteriological data in treatment of secondary peritonitis. We also describe in detail the anaerobic flora of secondary peritonitis, the unique susceptibility patterns of these organisms, and the specific virulence factors of anaerobes, particularly Bacteroides fragilis. The fact that clinical investigations sometimes result in treatment failure when gram-negative anaerobes are resistant to the antimicrobials used or when complete antimicrobial susceptibility data are not available emphasizes the need for accurate and early knowledge of the bacteriologic characteristic of the flora of the operative site. We emphasize the relationship of in vitro susceptibility of intraoperative isolates with clinical outcome. We propose a cooperative trial that would demonstrate that successful antimicrobial therapy should be based on the susceptibility of the flora of the operative site, which correlates with clinical outcome.

Adjunctive antimicrobial therapy for complicated appendicitis: bacterial overkill by combination therapy.

Although single antimicrobials with broad-spectrum aerobic and anaerobic coverage are effective in patients with appendicitis, many general surgeons continue to use multiple agents. A prospective, double-blind, randomized trial was designed to detect any clinical correlate of in vitro susceptibility advantage of multiple antimicrobials as adjunctive therapy for 114 patients undergoing operation for complicated appendicitis. There was clinical resolution of intraabdominal infections with no occurrence of postoperative infectious complications in 90% (36 of 40) of the cefotetan group and 86% (31 of 36) of the clindamycin/amikacin group (p = 0.11). The number of patients who had changes in antibiotic therapy due to postoperative complications was higher in the clindamycin/amikacin group: five (12.5%), compared to one (2.8%) in the cefotetan group (p = 0.07). Although Bacteroides fragilis group organisms resistant to cefotetan were identified, none was responsible for the postoperative infections. Adverse drug events in 28% of the cefotetan group and 26% of the clindamycin/amikacin group consisted primarily of transient elevations of liver function tests. Monotherapy with a second-generation, broad-spectrum cephalosporin, such as cefotetan, given twice a day is an economical and effective adjunctive regimen in patients with complicated appendicitis for which operation is the definitive treatment. Aminoglycosides and other, more potent antimicrobials should be reserved for resistant organisms or nosocomial infections.

Absence of minimal residual disease detectable by FACS, Southern blot or PCR in patients with chronic lymphocytic leukaemia treated with fludarabine.

We report the results of assessment of minimal residual disease in four patients with chronic lymphocytic leukaemia, who achieved clinical and haematological complete response following treatment with fludarabine. Patients were assessed both before and after treatment by immunophenotyping, DNA electrophoresis, Southern blotting and PCR amplification to detect immunoglobulin gene rearrangements. Immediately after treatment, no patient had disease detectable by any method and there was evidence of recovery of normal B-cells. No patient has yet shown evidence of clinical or haematological relapse (follow-up 59-142 weeks). Two patients remain in immunophenotypic and molecular remission at 141 and 59 weeks. These methods have allowed more sensitive definition of elimination of residual disease, with PCR demonstrating the capacity to detect disease recurrence before any other evidence is available.

Susceptibility of intra-abdominal isolates at operation: a predictor of postoperative infection.

Antimicrobial resistance of operative site flora was correlated with postoperative infection in 175 patients undergoing operation for intra-abdominal sepsis: Diagnoses for study patients were acute or gangrenous appendicitis in 48 (27%), complicated appendicitis in 98 (56%), perforated viscus other than appendix in 21 (12%), and eight (5%) had other intra-abdominal infections. One hundred thirty-six (78%) patients were males. The average age was 33 +/- 14 years, average number of hospital days was 11.6 +/- 13.5, and average number of days on antibiotics was 6.9 +/- 2.5. Overall recovery without infection was 75 per cent (131/175). Analysis of susceptibility of 939 intraoperative isolates indicated a significant relationship (P = 0.0002) between resistance to the empiric antimicrobials received and postoperative infection. Of 131 patients with resolution of the intra-abdominal infection, 57 (44%) had resistant isolates while 36 (82%) of 44 patients with postoperative infectious complications had resistant isolates. Streptococcus Group D, Escherichia coli, and Bacteroides fragilis were the most prevalent resistant organisms isolated from both intra- and postoperative cultures. Other variables that were significantly different between those without complications and those who had complications were, respectively: average age 31 versus 38; admission WBC 14.5 versus 16.7; and diagnosis, acute appendicitis 28 per cent versus 2 per cent. A stepwise logistic regression analysis confirmed the predictive value of intraoperative isolate resistance, age, and admission WBC, in that order, on outcome.

Simultaneous analysis of cell surface antigens and DNA content by flow cytometry.

Cells obtained from the blood or bone marrow of patients with haematological malignancies can both be stained with fluorescent labelled monoclonal antibodies to determine an immunophenotype and permeabilized with 30% ethanol then stained with propidium iodide for simultaneous DNA analysis. In the technique described here, no evidence of selective depletion of the malignant cell population was demonstrated and decreases in the mean fluorescence intensity of the surface markers were insufficient to affect the sensitivity of flow cytometric analysis. The combined method is simple and robust enough to allow incorporation of DNA analysis into routine immunophenotyping of leukaemia and lymphoma cells.

Cefepime for infections of the biliary tract.

Antibiotic treatment of biliary tract infections is widely accepted. An open, prospective, randomized, multicenter trial comparing cefepime (2 grams every 12 hours) with gentamicin (1.5 milligrams per kilograms every eight hours) plus mezlocillin (3 grams every four hours) for a minimum of five days was undertaken. Of the 149 patients enrolled, 120 were evaluable; 80 were randomized to receive cefepime and 40 were randomized to receive gentamicin plus mezlocillin (two to one randomization schedule). The diagnosis was acute cholecystitis in 101 patients and acute cholangitis in the remainder. There were no differences between the two treatment groups with regard to gender, age, disease, signs and symptoms, admitting temperature or laboratory values. All patients (100 percent) treated with gentamicin and mezlocillin were cured of the infection, as were 78 (97.5 percent) of the patients treated with cefepime (difference not significant). The incidence and spectrum of adverse events and complications were similar between the two groups (8.8 percent for cefepime versus 10 percent for gentamicin and mezlocillin). Our data show that the efficacy and safety of cefepime administered every 12 hours is equivalent to that of gentamicin and mezlocillin combination for treating patients with acute infections of the biliary tract. In addition, twice-daily administration of cefepime may be more cost-effective than the aminoglycoside-based combination.

Single pass sequencing and physical and genetic mapping of human brain cDNAs.

We have performed single pass sequencing of 1,024 human brain cDNAs, over 900 of which seem to represent new human genes. Library prescreening with total brain cDNA significantly reduced repeated sequencing of highly represented cDNAs. A subset of sequenced cDNAs were physically mapped to their chromosomal locations using gene-specific STS primers derived from 3' untranslated regions. We have also determined that human brain cDNAs represent a rich source of gene-associated polymorphic markers. Microsatellite-containing cDNAs can be physically mapped and converted to highly informative genetic markers, thus facilitating integration of the human physical, expression and genetic maps.

Molecular probe analysis of Shigella dysenteriae type 1 isolates from 1940 to 1987.

Fourteen strains of Shigella dysenteriae type 1 (Shiga bacillus) isolated from people in diverse locations from 1940 to 1987 were studied. Southern hybridization with three cloned Escherichia coli genes, Shiga-like toxin I (SLTI), frd, and ompF, was used to determine restriction fragment length polymorphism (RFLP) of the genomic DNA of these strains. Digestion with each of four restriction endonucleases generated fragments of identical size to which the frd and ompF hybridized for each of the 14 strains, indicating the conservation of these genes and their flanking sequences. In contrast, after digestion with HindIII, EcoRV, and ClaI and probing with SLTI, there were RFLP among the strains. The results showed three clones of the Shiga bacillus, and suggested that dissemination of a single clone may continue for decades within a wide geographical area.

Adjunctive antimicrobials in surgery of soft tissue infections: evaluation of cephalosporins and carbapenems.

The authors report three trials of B-lactams and carbapenems for soft tissue infections treated on a surgical service: 1) cefmetazole versus cefoperazone, n = 44; 2) cefotetan versus cefoxitin, n = 24; and 3) meropenem versus imipenem, n = 44. A total of 138 hospitalized patients were enrolled with 112 meeting evaluability criteria. Four hundred twenty-three isolates were cultured (mean, three/patient) of which 67 per cent were aerobes and 33 per cent anaerobes. Cure rates for each trial were: 1) 93 per cent; 2) 92 per cent; 3) 100 per cent. Failures were caused by resistant organisms (Streptococcus group D, Bacteroides fragilis and Pseudomonas) appearing in incompletely drained infection sites. Three patients receiving meropenem had adverse effects (headache, nausea) and one receiving cefoxitin (truncal rash). Operative drainage and debridement remain the critical elements in therapy. Agents with longer half lives allowing twice daily dosing (cefmetazole and cefotetan) were as effective and less expensive than multiple doses of short-acting agents. The extended spectrum carbapenems are most useful for severe infections or resistant organisms.