Evaluation of the AutoMicrobic system Gram-Negative General Susceptibility-Plus Card.

The MICs of 10 antimicrobial agents were determined for 1,000 clinical aerobic and facultatively anaerobic gram-negative bacilli by the 6-h AutoMicrobic system Gram-Negative General Susceptibility-Plus Card (GSC+) (Vitek Systems, Inc., Hazelwood, Mo.) and by an 18-h reference agar dilution method. Results obtained by both systems were evaluated for twofold dilution discrepancies and for interpretive category discrepancies. MICs that differed by more than one twofold dilution between the two test systems were considered to be discrepant. The overall twofold dilution agreement of the GSC+ MICs to agar dilution MICs was 94.0%. The agreement for each drug tested ranged from 91.7% (ampicillin and chloramphenicol) to 96.5% (carbenicillin). Interpretive categories were considered in agreement when the susceptibility interpretations obtained by the two systems were both very susceptible, moderately susceptible, or resistant. The overall interpretive category agreement was 80.5%. This agreement increased to 95.8% when all minor errors (moderately susceptible, one system; very susceptible, the other system) that would not affect therapy were omitted. The AutoMicrobic system GSC+ provides rapid and accurate susceptibility test results for clinical aerobic and facultatively anaerobic gram-negative bacilli.     

Differentiation of Brucella ovis from Brucella abortus by gas-liquid chromatographic analysis of cellular fatty acids

The cellular fatty acid composition of Brucella ovis and Brucella abortus strains was determined by gas-liquid chromatography. Both species were characterized by the presence of fatty acids 16:0, 17:0, 17:0 cyclopropane, 18:0, 18:1, and 19:0 cyclopropane; B. ovis also contained some 15:0. There were differences in the relative proportions of the fatty acids present, and it was possible to differentiate B. ovis from B. abortus on the basis of the absence of 15:0, lower concentrations of 17:0 and 18:1, and higher concentrations of 19:0 cyclopropane in B. abortus. The data indicate that analysis of cellular fatty acid composition by gas-liquid chromatography can be used for the identification of B. ovis and its differentiation from B. abortus.     

Kinesiological studies of self- and cross-reinnervated FDL and soleus muscles in freely moving cats

The activity patterns in self- and cross-reinnervated flexor digitorum longus (FDL) and soleus (SOL) muscles were examined during natural movements in awake, unrestrained cats in which electromyographic (EMG) electrodes, tendon-force gauges, and muscle-length gauges had been chronically implanted under anesthesia and aseptic conditions. Kinesiological data were recorded between 13 and 22 mo after nerve surgery. Self-reinnervated FDL and SOL muscles (i.e., FDL----FDL and SOL----SOL, respectively) exhibited locomotor activity patterns that were the same as observed in normal, unoperated FDL and SOL muscles (26). FDL----FDL muscles exhibited primarily brief bursts of activity in early swing, just after the toes had left the ground, whereas SOL----SOL muscles showed bursts of activity just before and during stance. In contrast, the cross-reinnervated muscles (both SOL----FDL and FDL----SOL) that had little or no unwanted self-reinnervation showed the patterns of activity that are associated with the innervating foreign motoneurons. That is, cross-reinnervated SOL----FDL muscles were intensely active in quadrupedal standing and, during the stance phase of stepping, producing large force transients while actively lengthening. Conversely, cross-reinnervated FDL----SOL muscles were active mainly in short bursts at the onset of the swing phase of stepping, just after the foot had left the ground. There was considerable modulation of EMG and peak force output in FDL----SOL muscles with changing speed of locomotion, whereas little modulation was evident in SOL----FDL muscles. The activity patterns in self- and cross-reinnervated FDL and SOL muscles were also recorded during scratch and paw-shaking reflexes. As in locomotion, the observed patterns were in all cases consistent with those expected for the innervating motor pool rather than the innervated muscle. Muscles that had been dually reinnervated by both the original and foreign motor pools displayed activity patterns that were a mixture of the FDL and SOL activity patterns described above. The present results demonstrate that motoneuron activation patterns remain qualitatively unaltered when their motor axons reinnervate foreign muscles. In addition, the observations permit some quantitative estimates of the degree to which cross-reinnervated muscles are subjected to patterns of motoneuron activity and to conditions of mechanical loading that are markedly different from those in the self-reinnervated or normal conditions.     

Electrotonic characteristics of alpha motoneurones of varying size

1. The neuronal membrane responses to long constant current pulses (essentially current steps) have been studied in cat triceps surae motoneurones identified as to the type of muscle fibres, fast twitch (type F) or slow twitch (type S), innervated by the cell being studied. For each motoneurone the membrane time constant, τ_M, and input resistance, R_N, were determined from the response to a current step. In addition, shorter time constants (`equalizing time constants') resulting from current spread into the dendrites were estimated by graphical analysis.

2. The electrotonic length of the combined motoneurone soma and dendritic tree was estimated from the current step data using the neuronal equivalent cylinder model formulated by Rall (Rall, 1969). The mean electrotonic length of the motoneurone equivalent cylinder was approximately 1·5 in both type F and type S motoneurones. The mean membrane time constant of type F cells was 5·6 msec and that of type S motoneurones was 6·7 msec. This difference in mean τ_M values was of border line statistical significance.

3. The results indicate that the electrotonic length of the combined dendritic trees of both large type F and small type S motoneurones is essentially the same. The implication of this conclusion for interpretation of previous analyses of the monosynaptic EPSP is discussed.

     

Screening protocol for Torulopsis (Candida) glabrata.

A screening test has been developed for the presumptive identification of Torulopsis (Candida) glabrata from other common clinical isolates of yeast-like fungi. An interlaboratory comparison of a protocol consisting of morphology on cornmeal Tween 80 agar and trehalose fermentation at 42 degrees C was successful in differentiating T. glabrata from other taxa that are frequent or possible clinical isolates. The screening results for 517 clinical yeast isolates, 241 of which were T. glabrata, were compared with their final identification via commercial systems (API20C Yeast Identification System [bioMERIEUX, Hazelwood, Mo.] and Rapid Yeast Identification Panel [Dade Microscan, Sacramento, Calif.]). The trehalose screening test has a sensitivity and a specificity of 97.8 and 95.8%, respectively, and a positive predictive value of 97.4% and a negative predictive value of 96.5%. Overall, the trehalose screen had an efficiency rating of 93.9% for ruling in or out T. glabrata. Since T. glabrata represents a substantial part of the workload in a clinical laboratory, a significant reduction in direct and indirect costs should be realized.     

Patients with suspected myocardial infarction: effect of mode of referral on admission time to a coronary care unit.

The aim of this prospective study was to determine the delay between the onset of symptoms and arrival in the coronary care unit of patients with suspected acute myocardial infarction, and the relative contribution to the total delay of patient delay, method of referral (self referral or general practitioner referral) and delay in the hospital before reaching the coronary care unit. All patients admitted with chest pain to the coronary care unit at Dudley Road Hospital, Birmingham, over the six month period April-September 1989 were included in the study. Ninety five patients were referred by their general practitioner and 107 patients attended the accident and emergency department directly or arrived by ambulance without contacting their general practitioner. The proportion of self referred and general practitioner referred patients with acute myocardial infarction, angina and non-cardiac chest pain were not significantly different. The total delay was significantly longer for patients who had been referred by their general practitioner (median 5.3 hours) than for self referrals (3.2 hours, P less than 0.001), with a significantly higher proportion of self referrals arriving at the coronary care unit within six hours of the onset of symptoms (77% versus 54%, P less than 0.01). Among general practitioner referrals, initial patient delay accounted for a median of 2.5 hours and the general practitioner's response time for a median of 1.1 hours. The delay in hospital was similar for both groups of patients. In inner city areas, self referral may result in considerably less delay than general practitioner referral allowing a greater proportion of patients to receive effective thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Inhibition of experimental autoimmune encephalomyelitis in Lewis rats by nasal administration of encephalitogenic MBP peptides: synergistic effects of MBP 68-86 and 87-99

Induction of mucosal tolerance by inhalation of soluble peptides with defined T cell epitopes is receiving much attention as a means of specifically down-regulating pathogenic T cell reactivities in autoimmune and allergic disorders. Experimental autoimmune encephalomyelitis (EAE) induced in the Lewis rat by immunization with myelin basic protein (MBP) and Freund's adjuvant (CFA) is mediated by CD4+ T cells specific for the MBP amino acid sequences 68-86 and 87-99. To further define the principles of nasal tolerance induction, we generated three different MBP peptides (MBP 68-86, 87-99 and the non- encephalitogenic peptide 110-128), and evaluated whether their nasal administration on day -11, -10, -9, -8 and -7 prior to immunization with guinea pig MBP (gp-MBP) + CFA confers protection to Lewis rat EAE. Protection was achieved with the encephalitogenic peptides MBP 68-86 and 87-99, MBP 68-86 being more potent, but not with MBP 110-128. Neither MBP 68-86 nor 87-99 at doses used conferred complete protection to gp-MBP-induced EAE. In contrast, nasal administration of a mixture of MBP 68-86 and 87-99 completely blocked gp-MBP-induced EAE even at lower dosage compared to that being used for individual peptides. Rats tolerized with MBP 68-86 + 87-99 nasally showed decreased T cell responses to MBP reflected by lymphocyte proliferation and IFN-gamma ELISPOT assays. Rats tolerized with MBP 68-86 + 87-99 also had abrogated MBP-reactive IFN-gamma and tumor necrosis factor-alpha mRNA expression in lymph node cells compared to rats receiving MBP 110-128 nasally, while similar low levels of MBP-reactive transforming growth factor-beta and IL-4 mRNA expressing cells were observed in the two groups. Nasal administration of MBP 68-86 + 87-99 only slightly inhibited guinea pig spinal cord homogenate-induced EAE, and passive transfer of spleen mononuclear cells from MBP 68-86 + 87-99-tolerized rats did not protect naive rats from EAE. Finally, we show that nasal administration of MBP 68-86 + 87-99 can reverse ongoing EAE induced with gp-MBP, although higher doses are required compared to the dosage needed for prevention. In conclusion, nasal administration of encephalitogenic MBP peptides can induce antigen-specific T cell tolerance and confer incomplete protection to gp-MBP-induced EAE, and MBP 68-86 and 87-99 have synergistic effects. Non-regulatory mechanisms are proposed to be responsible for tolerance development after nasal peptide administration.      

Interactions between cyclosporin A, indomethacin and 16,16-dimethyl prostaglandin E2: effects on renal, hepatic and gastrointestinal toxicity in the rat

Rats were treated for 3 or 14 days with cyclosporin A (CsA, 50 mg/kg) or indomethacin (2 or 5 mg/kg) either alone or in combination, or with CsA plus 16,16-dimethylprostaglandin E2 (DMPGE2, 0.25 mg/kg). Hepatic and renal function were unaffected by treatment with indomethacin at either dose and only at the higher dose was severe intestinal ulceration observed. CsA caused renal and hepatic toxicity, evidenced by increased urine N-acetyl-beta-D-glucosaminidase activity, serum urea, creatinine and bilirubin and decreased serum albumin and total protein. In rats cotreated with CsA and either dose of indomethacin the increases in serum urea and creatinine and decreases in serum albumin and total protein were accentuated, but serum bilirubin was not further increased. Intestinal lesions were present in rats treated for 14 days with CsA plus the lower dose of indomethacin, but not in rats treated with either drug alone. In rats treated with DMPGE2 plus CsA, serum urea and creatinine were normal and urine N-acetyl-beta-D-glucosaminidase activity was reduced compared to rats treated with CsA alone, but DMPGE2 cotreatment had no effect on the CsA induced hyperbilirubinaemia. Hepatic microsomal cytochrome P-450 concentration and aminopyrine N-demethylase activity were lower in rats treated with CsA plus indomethacin than in untreated rats or those treated with either drug alone. Coadministration of indomethacin or DMPGE2 had no effect on serum trough CsA levels. The results are interpreted as showing an exacerbation by CsA of the intestinal toxicity of indomethacin, an increase by indomethacin in the renal toxicity of CsA and a protection by DMPGE2 against CsA renal toxicity. Possible mechanisms involving drug interactions and either hepatic cytochrome P-450, renal cyclooxygenase or other renal sites are discussed.