Lawrence F. Freundlich

Contrasting effects of identical nutrients given parenterally or enterally after 70% hepatectomy: bacterial translocation.

High mortality occurs in rats with 70% hepatectomy fed intravenous (IV) total parenteral nutrition (TPN; 13.9% glucose, 4.17% amino acids, 1.46% fat, electrolytes, trace minerals, and vitamins providing 216 kcal.kg-1.d-1) but not when the identical nutrients are given at the same rate enterally (gastrostomy). We hypothesized that a difference in bacterial translocation (BT) was a contributing factor to this phenomenon. Forty-five male Sprague-Dawley rats (300-360 g) were divided into five groups and underwent the following: control (no operation), sham (intraperitoneal [IP] pentobarbital anesthesia, central venous and gastrostomy catheters, laparotomy, sham hepatectomy), standard oral feeding (SOF), TPN (IV nutrients), and total enteral nutrition (TEN; gastrostomy). The SOF, TPN, and TEN groups had IP pentobarbital anesthesia, central venous and gastrostomy catheters, and 70% hepatectomy. Postoperatively, control and SOF (both catheters plugged) rats ate a commercial rat chow and drank tap water ad libitum pre- and postoperatively. The sham, TPN, and TEN groups were given the identical infusate composition as above, but the nutrient concentrations were cut in half (110 kcal/kg) and three-quarters (165 kcal/kg) on postoperative days 1 and 2, respectively. At the end of postoperative day 2, all rats were euthanized. BT to mesenteric lymph nodes (MLNs), liver, spleen, and lungs was significantly higher in the TPN rats compared with all other groups, except that BT to the MLNs was similar in the TPN and TEN groups. Bacteremia was found only in the TPN rats. BT in TPN rats with 70% hepatectomy was significantly greater 48 h after operation than in those fed the identical nutrients enterally at the same rate; this correlates with the previously reported significantly greater mortality in rats with 70% hepatectomy receiving TPN.

In vitro Antibiotic Sensitivity of Moraxella Species

Minimal inhibitory concentrations of 17 antibacterial agents for 34 Moraxella strains were determined using a plate dilution method. A strain of Moraxella nonliquefaciens was found which produced beta-lactamase and was resistant to ampicillin and carbenicillin but not to cephalothin. Several strains were relatively resistant to erythromycin and sulfisoxazole. Disk sensitivity tests could be used to reliably predict penicillin and erythromycin resistance but not sulfisoxazole resistance.

High-sensitivity radioassay of chromatographic effluents : Automatic fraction collector/concentrator for quantitative autoradiography

Abstract We modified an automatic micro-fraction collector for fractionating the effluent of a high-pressure chromatography column and concentrating the fractions for radioassay by autoradiography. A succession of aliquots of up to 300 μl of effluent is deposited in wells formed in non-wetting fluorocarbon film. After evaporation to near dryness, the remaining droplets are quantitatively transferred to filter paper where they form uniform spots 2–3 mm in diameter. The paper is then exposed to photographic film for a time determined by the radioactivity of the sample. The film is then developed and the density of the radioautograph scanned. Most of the resolution of high-performance liquid chromatography (HPLC) was preserved. In HPLC of amino acids with a flow-rate of 1 ml/min, we collected fractions of 125 μl every 7.5 s. The proline peak, which the UV detector measured 21 s wide at half-height, was 23 s wide at half-height on the radioactivity record. After 6 h of radioautography, 1000 dpm of 14 C in a 3-mm diameter spot produced approximately 0.2 absorbance units above film background. Absorbance was proportional to radioactivity from 160 to 2500 dpm. With 1 week of exposure, absorbance was proportional and radioactivity could by quantified in spots containing from 5 to 80 dpm.

Sensitivity of Gentamicin-Resistant Enterobacteriaceae to Cefamandole and Cefoxitin

A collection of gentamicin-resistant Enterobacteriaceae strains was significantly more resistant to cefamandole than a species-matched collection of gentamicin-sensitive organisms. Cefamandole and gentamicin resistance could be simultaneously transferred by conjugation from four different species, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae and Serratia marcescens, to a recipient E. coli strain. Plasmids specifying linked resistance to cefamandole and gentamicin are thus commonly present in the environment of our medical center despite the fact that cefamandole has never been used here. Gentamicin-resistant organisms were not more resistant to cefoxitin than gentamicin-sensitive isolates. Conjugal transfer of cefoxitin resistance could not be demonstrated. Relative resistance to cefoxitin was nevertheless common among Enterobacter and Serratia isolates.

Confirming chiral high-performance liquid chromatographic separations with stereospecific enzymes

Abstract Identification of optical isomers of amino acids, separated by chiral high-performance liquid chromatography, has proved to be difficult. Despite highly selective separation techniques, identification of peaks based on retention times alone is usually uncertain, particularly in assays of complex biological samples in which interfering compounds are eluted with the peak of interest. We describe here an approach for increasing the certainty of identification of peaks of d - and l -amino acids by the use of stereospecific amino acid oxidase and racemase enzymes. A portion of the sample is first incubated with the enzymes. The amino acids in the treated and untreated portions are then chromatographed and the chromatograms of the samples with and without enzyme incubation are compared. The differences are used to help identify the amino acids.

Room temperature incubation of dipslide urine cultures

Two hundred and fifty urine specimens selected at random were cultured simultaneously by routine methods and on dipslides containing MacConkey agar and cystine-lactose electrolyte deficient agar with colistin (CLED-colistin agar) at room temperature incubation. There were six major and five minor differences between the two methods in interpretation of results. Many of these differences were due to the fact that CLED-colistin agar fails to support the growth of many gram-positive species, and that the dipslide tended to overestimate the colony count. Nevertheless there was sufficient agreement between the two methods to suggest that dipslides can be used effectively in office or clinic without the need for an incubator.