Pathogenesis of Shigella diarrhea: rabbit intestinal cell microvillus membrane binding site for Shigella toxin

This study examined the binding of purified 125I-labeled shigella toxin to rabbit jejunal microvillus membranes (MVMs). Toxin binding was concentration dependent, saturable, reversible, and specifically inhibited by unlabeled toxin. The calculated number of toxin molecules bound at 4 degrees C was 7.9 X 10(10) (3 X 10(10) to 2 X 10(11))/micrograms of MVM protein or 1.2 X 10(6) per enterocyte. Scatchard analysis showed the binding site to be of a single class with an equilibrium association constant, K, of 4.7 X 10(9) M-1 at 4 degrees C. Binding was inversely related to the temperature of incubation. A total of 80% of the labeled toxin binding at 4 degrees C dissociated from MVM when the temperature was raised to 37 degrees C, but reassociated when the temperature was again brought to 4 degrees C. There was no structural or functional change of MVM due to toxin as monitored by electron microscopy or assay of MVM sucrase activity. These studies demonstrate a specific binding site for shigella toxin on rabbit MVMs. The physiological relevance of this receptor remains to be determined.     

Neopterin as a new biochemical marker in the clinical assessment of ulcerative colitis

In previous publications we showed that neopterin, a pyrazino-pyrimidin compound, represents a biochemical marker for the assessment of cellular immune responses. We thought that the evaluation of this marker molecule might enable insight into the activity of cellular immune responses underlying ulcerative colitis (UC). Evaluation of urinary neopterin excretion in 25 consecutive untreated UC patients revealed striking correlations between neopterin levels and the severity of disease: elevated levels were observed in 9 out of 9 patients with moderately severe to severe, in 3 of 4 with mild and in none of 12 patients with quiescent disease. Further evidence for a correlation between disease activity and neopterin excretion was obtained on the basis of long-term follow-up studies performed in 4 cases. These studies indicated normalization of neopterin levels when clinical remission was achieved. Thereafter, the relative significance of neopterin excretion for determination of clinical stage was assessed by linear correlation analyses and was compared with conventional clinical parameters such as anemia, number of motions per day, raised temperature, ESR and extent of bowel involvement. The logarithm of neopterin excretion and the extent of bowel involvement were the two single parameters most closely related to the clinical stage of ulcerative colitis. We, therefore, conclude that evaluation of neopterin excretion in ulcerative colitis patients represents a new and useful tool for the clinical monitoring of disease activity.     

Use of non-neutralizing monoclonal antibodies in an ELISA for intratypic differentiation of 28 echovirus type 25 clinical isolates.

Three non-neutralizing monoclonal antibodies were produced and selected against echovirus type 25 JV-4 prototype strain. They were used in an ELISA to investigate the intratypic differentiation of 28 wild isolates. Clinical isolates fell into seven different groups according to their reactivity patterns in ELISA. Two of the non-neutralizing monoclonal antibodies, 9E4 and 6D3, were highly specific, while the third, 6C9, may recognize an epitope common to other types of echoviruses. In contrast, mouse polyclonal antiserum exhibited large cross-reactivities among echovirus serotypes. The reactivity patterns and the geographical origin of the isolates were generally not correlated and, in the same area, four major antigenic variants sometimes coexisted, especially in the south of France. Moreover, reactivity patterns found with ELISA were hardly ever correlated with those observed in a previous study when neutralization tests were used. These results again underline the non-correlation between structure and biological function in the Picornavirus family.     

Physiological and behavioral identification of vestibular nucleus neurons mediating the horizontal vestibuloocular reflex in trained rhesus monkeys.

1. To describe in detail the secondary neurons of the horizontal vestibuloocular reflex (VOR), we recorded the extracellular activity of neurons in the rostral medial vestibular nucleus of alert, trained rhesus monkeys. On the basis of their activity during horizontal head and eye movements, neurons were divided into several different types. Position-vestibular-pause (PVP) units discharged in relation to head velocity, eye velocity, eye position, and ceased firing during some saccades. Eye and head velocity (EHV) units discharged in relation to eye velocity and head velocity in the same direction so that the two signals partially canceled during the VOR. Two cell types discharged in relation to eye position and velocity but not head velocity; other types discharged in relation to head velocity only. 2. The position in the neural path from the primary vestibular afferents to abducens motoneurons was examined for each type. Direct input from the vestibular nerve was indicated if the cell could be activated by shocks to the nerve at latencies less than or equal to 1.4 ms. A projection to abducens motoneurons was indicated if spike-triggered averaging of lateral rectus electromyographic (EMG) activity yielded responses with a sharp onset at monosynaptic latencies. 3. PVP neurons were the principal interneuron in the VOR "three-neuron arc." Eighty percent received primary afferent input, and 66% made excitatory connections with contralateral abducens motoneurons. Surprisingly few, approximately 11%, made inhibitory connections with ipsilateral abducens motoneurons. This imbalance in the ipsi- and contralateral projections was confirmed by measuring the EMG activity evoked by electrical microstimulation in regions where PVP neurons were located. 4. EHV neurons whose activity increased during contralaterally directed head or eye movements were also interneurons in the ipsilateral inhibitory pathway. Eighty-nine percent received ipsilateral primary afferent input, and 25% projected to ipsilateral abducens motoneurons. EHV neurons excited during ipsilateral movements received neither direct primary afferent input nor projected to either abducens nucleus. A small proportion of each of two other cell types having sensitivity to contralateral eye position made excitatory connections with contralateral abducens motoneurons. Other types rarely were activated from the eighth nerve or projected to the abducens nucleus. 5. The significance of the connections of VOR interneurons and the signals they convey is discussed for three situations: smooth pursuit of a moving target, suppression of the VOR, and the VOR itself. PVP neurons convey a signal with a ratio of eye position and velocity components that is inappropriate to drive motoneurons during pursuit or the VOR.(ABSTRACT TRUNCATED AT 400 WORDS)     

In vitro activity of ceftizoxime,ceftazidime, cefuroxime,ceftriaxone, cefotaxime,and penicillin againstStreptococcus pneumoniae as determined by three quantitative methods

E-test, broth microdilution, and agar dilution susceptibility tests were used to evaluate penicillin and five extended-spectrum cephalosporins against 196 strains ofStreptococcus pneumoniae with different levels of penicillin resistance. Oxacillin disk tests corresponded to minimum inhibitory concentrations of penicillin determined by the E-test better than those generated by broth microdilution or agar dilution methods. Relative potency of the study drugs was as follows: cefotaxime=ceftriaxone > penicillin > cefuroxime > ceftizoxime > ceftazidime.     

Is the Parkland formula still the best method for determining the fluid resuscitation volume in adults for the first 24 hours after injury? — A retrospective analysis of burn patients in Germany

BackgroundR Rapid fluid resuscitation is a crucial therapy during the treatment of patients with extensive burns. In 1968, the Parkland Formula was introduced for the calculation of the estimated volume of the resuscitation fluid. Since then, different methods for the calculation of fluid resuscitation volume have been developed. We aimed to evaluate if the Parkland formula is still the most effective method for fluid resuscitation volume calculation in burn patients.MethodsIn the period between January 2015 and January 2019, data from 569 patients over 16 years old with burns of more than 20% total body surface area (TBSA) and at least 15% TBSA full thickness burns were entered in the German burn registry. The patients were divided into 5 groups (0, +1, ?1, +2, ?2) according to the volume of the resuscitation fluid they received. Group 0 patients received the amount of fluid calculated according to the Parkland formula (n = 83). The 4 other groups received reduced (-1, -2) or increased (+1, +2) fluid volumes in comparison to the value obtained by the Parkland formula.ResultsPatients in Group 0 presented a significantly lower mortality in the first week (4.5%) compared to groups –2 (16.7%) and group +2 (19.5%) (p = 0.021). Furthermore, the mean number of operations in group +2 (5.81) was higher than in group ?2 (3.81). Surviving patients from group +2 presented a longer hospital stay (68.1 days) compared to the other groups. Additionally, the logistic regression analysis showed a higher survival of patients in groups ?2 and ?1 (regression coefficients ?0.11 and ?0.086; Odds Ratio 0.896 and 0.918; 95% Confidence Interval (CI) 0,411–1.951 and 0.42–2.004).ConclusionIn this retrospective study, register based analysis a restrictive fluid regime was associated with a higher survival compared to the liberal Parkland guided fluid regime.