Dissolved carbon dioxide and oxygen concentrations in purge of vacuum-packaged pork chops and the relationship to shelf life and models for estimating microbial populations.

The objectives of this study were to determine the dissolved CO2 and O2 concentrations in the purge of vacuum-packaged pork chops over a 60 day storage period, and to elucidate the relationship of dissolved CO2 and O2 to the microbial populations and shelf life. As the populations of spoilage bacteria increased, the dissolved CO2 increased and the dissolved O2 decreased in the purge. Lactic acid bacteria dominated the spoilage microflora, followed by Enterobacteriaceae and Brochothrix thermosphacta. The surface pH decreased to 5.4 due to carbonic acid and lactic acid production before rising to 5.7 due to ammonia production. A mathematical model was developed which estimated microbial populations based on dissolved CO2 concentrations. Scanning electron microscope images were also taken of the packaging film to observe the biofilm development. The SEM images revealed a two-layer biofilm on the packaging film that was the result of the tri-phase growth environment.

Corticosteroids do not alter the threshold for vertebral fracture.

Corticosteroid use is one of the most important secondary causes of osteoporosis. Generally, it has been believed that in addition to its effect on bone mineral density (BMD), it also causes an alteration in bone quality that means that fractures occur at a lower BMD than might be expected. To establish if this is the case, we have compared the relationship between BMD and vertebral fracture in patients receiving corticosteroids with that in patients who had never received such therapy. Information was gathered on those patients who had been referred to the participating centers and had both BMD measurements and lateral thoracolumbar radiographs. In all, 452 patients (391 female) were identified; of these 82 (63 female) were receiving corticosteroids. There was no significant difference in BMD between the patients on corticosteroids and those with other suspected causes of osteoporosis. Vertebral fractures were present in 53% of patients on steroids compared with 35% of those who had no such treatment (p = 0.0035). The fractures were more likely to be multiple in patients on corticosteroids (p = 0.0042). However, if the relationship between bone density and fracture is investigated by plotting the cumulative prevalence of fracture against the bone density, measured by T score, the median BMD for fractures actually was marginally lower in patients on steroids, -2.74 (95% confidence interval [CI], -2.77 to -2.70) compared with -2.65 (95% CI, -2.66 to -2.65) in those who had not received steroids. Our results fail to support the notion that the fracture threshold is altered in patients on long-term steroids and suggest that the same diagnostic criteria should be used for osteoporosis in patients whether or not they are taking corticosteroid therapy.

Electrolyte disorders in the elderly.

Electrolyte abnormalities in the elderly are common and it is most important to establish if drug treatment is the cause, as this is so easily remediable. The vast majority of electrolyte disturbances will settle with treatment of the underlying condition. Great attention must be paid to fluid balance to establish if the patient is receiving too little, which could induce hypernatraemia, or too much, particularly after surgery, which may induce hyponatraemia. Electrolyte levels should be checked ideally before and certainly after the prescription of diuretics. In the elderly it is important that the electrolyte levels be checked if the patient exhibits any vague symptoms, particularly if they are taking a diuretic. Care must be taken in replacing potassium as in most cases this is unnecessary and may have a significant morbidity.

Hyperbaric oxygen as adjunctive therapy for osteomyelitis.

Mechanistically, hyperbaric oxygen (HBO) appears useful for the treatment of osteomyelitis. HBO increases the oxygen tension in infected tissue, including bone. An adequate oxygen tension is necessary for oxygen-dependent killing of organisms by the polymorphonuclear leukocytes and for fibroblast activity leading to angiogenesis and wound healing. HBO has a direct bacteriocidal or bacteriostatic effect on anaerobic organisms. In addition, HBO augments the killing of Pseudomonas aeruginosa by the aminoglycoside--tobramycin. At the University of Texas Medical Branch at Galveston, adjunctive HBO is used for the Cierny Mader stage 3B and 4B osteomyelitis.

Comparative evaluation of the diffusion of tobramycin and cefotaxime out of antibiotic-impregnated polymethylmethacrylate beads.

Both tobramycin and cefotaxime diffuse from antibiotic-impregnated polymethylmethacrylate (PMMA) beads in quantities sufficient to inhibit the growth of bacteria on agar lawns or in broth cultures over a 28-day period. Extraction of antibiotic from tobramycin or cefotaxime-impregnated PMMA beads revealed that substantial amounts of both antibiotics remained within the beads despite 28 days of diffusion. Diffusion of antibiotic from the PMMA beads during the initial 3-5 days is much greater than occurs for the remainder of the 4-week period. The results of the study suggest that perhaps tobramycin of cefotaxime-impregnated PMMA beads would produce local levels of antibiotic high enough to sterilize a given dead space for a period of 28 days.

Comparative evaluation of A-56619, A-56620, and nafcillin in the treatment of experimental Staphylococcus aureus osteomyelitis.

A rabbit model for Staphylococcus aureus osteomyelitis was used to compare the results of treatment with A-56619 and A-56620, two new aryl-fluoroquinolones, and nafcillin. A-56619 (15 mg/kg) and A-56620 (20 mg/kg), both used for 28 days of treatment, were injected subcutaneously every 12 h, and nafcillin (40 mg/kg) was injected every 6 h. After treatment, S. aureus was found on bone marrow cultures from 19 of 20 control rabbits, 6 of 20 treated with A-56619, 14 of 20 treated with A-56620, and 8 of 20 treated with nafcillin. Drug concentrations in serum and uninfected and infected bone were measured 1 h after A-56619 and A-56620 injection and 30 min after nafcillin injection in a group of rabbits that had been infected for 3 to 4 weeks. The concentrations in infected bone were similar for all three drugs and were significantly higher than in uninfected bone. The results of this study showed that A-56619 had a high rate of eradication of S. aureus from infected bone and compared favorably to nafcillin.

Are cervical spine radiographs of value in elderly patients with vertebrobasilar insufficiency?

Radiographs of the cervical spine of 32 elderly patients clinically diagnosed as having vertebrobasilar insufficiency secondary to cervical spondylosis were compared with 32 age- and sex-matched controls. The mean age was 77.6 years. There was no significant difference in the severity of the radiological changes between the two groups as judged by the narrowing of disc space and marginal osteophyte formation. It is concluded that there is no place for routine examination of the cervical spine in patients thought to have vertebrobasilar insufficiency secondary to cervical spondylosis.

A clinical and pharmacokinetic study of indomethacin in standard and slow release formulations.

Fifteen patients with rheumatoid arthritis received indomethacin in three treatment schedules; indomethacin retard 75 mg twice daily; indomethacin capsules 50 mg three times daily; and indomethacin 100 mg suppository at night with 50 mg by mouth each morning. The study was a double-blind, double-dummy one with each treatment being given for 2 weeks after a washout period of 3 days. After the washout period, and at the end of each 2 week active treatment period, blood samples were taken during a dosage interval for assay of indomethacin concentrations in plasma. Clinical assessments were also performed. All three treatment period produced significant clinical improvements in the assessments compared with the placebo washout period. However, no differences were seen between the treatments. Side effects occurred with equal frequency in all three periods, and the anticipated reduction in central nervous system side effects during the indomethacin retard period was not seen. Plasma concentrations of indomethacin were significantly higher during indomethacin retard therapy with a peak concentration of 2500 +/- 25 ng ml-1 during indomethacin retard therapy (mean +/- s.d.) and 1900 +/- 200 ng ml during conventional oral therapy. Indomethacin retard is as effective as the other formulations of indomethacin but appears to offer no significant advantages.