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S Segal

Publications and source records attributed to S Segal.

747 records · Page 42Linked to original sources
PubMedDate not supplied

Modulation of the immune response by antibacterial antibodies.

Antibodies induced by the gram+ bacteria Micrococcus lysodeikticus exhibit different carbohydrate specificities and hence might cross-react with membrane glycoproteins and/or glycolipids of mammalian cells. Using a T cell derived lymphoid line, these antibodies were found to detect a membrane marker which is only exposed in confluent culture conditions on non-dividing cells. Such confluence related antigen (Cag) is a cryptic membrane antigen, which can be unmasked through membrane perturbating agents such as p-formaldehyde or through interactions with macrophages and macrophage derived factors. Anti-micrococcus antibodies appear also to affect functionally normal T lymphocytes. Thus such reagents drastically inhibit the murine T cell reactivity towards mitogens such as Con A and PHA provided, however, the mitogenic signal is delivered through peritoneal macrophages. Furthermore, anti-micrococcus antibodies induce activated T lymphocytes into mitogenesis, but not unprimed resting T cells. Hence the physiological activity of anti-micrococcus antibodies depends on the state of activation of the T lymphocyte, indicating the involvement of cryptic membrane molecules. The relevance of such phenomena to host-bacteria and host-parasite interaction will be discussed.

Animals↗
PubMedDate not supplied

Vaginal and urinary cytology and blood hormonal examinations in patients with premature rupture of membranes.

Vaginal smears and urinary sediments of 29 pregnant women in their third trimester with premature rupture of membranes (PRM) were examined. Plasma radioimmunoassays (RIA) for estriol, human chorionic gonadotropin, human placental lactogen and progesterone were performed. Twenty-three normal pregnant women in the third trimester, serving as controls, underwent the same examinations. The vaginal smears and urinary sediments were evaluated as reflecting disturbed, slightly disturbed and normal placental function. Good correlation was found between the vaginal smears showing the typical and suggestive aspects of PRM and the placental function reflected in the same smears and the respective urinary sediments. From the hormonal examinations performed, the plasma RIA for progesterone presented significantly lower results in the PRM cases than in the control group. The results obtained suggest a lowering of the placental function in cases with PRM as reflected in cytologic and hormonal examinations.

Chorionic Gonadotropin↗
PubMedDate not supplied

Some aspects of the humoral immunity and the phagocytic function in newborn infants.

Newborn infants, particularly those born prematurely, are prone to develop life-threatening pyogenic infections. Different studies have demonstrated impairment of various aspects of the humoral immunity and the phagocytic activity of neutrophils in newborns. We conducted a comprehensive study evaluating the complement function (CH50 and AP50) and the level of the vast majority of the complement components (Clq, Clr, Cls, C2-C9, FB and properdin) in preterm and full-term newborn infants as compared to adults. Furthermore, we investigated the effect of autologous and heterologous serum on the bactericidal activity of neutrophils, by crossing newborn serum with adult cells and vice versa. Results showed that preterm and full-term newborns have an impaired complement activity as compared to adults (CH50 P < 0.05, AP50 < 0.01) and significantly reduced complement components except for C7, which was found to be normal in full-term infants and in most appropriate-for-gestational age preterm newborns at 34-36 weeks. A statistically significant correlation was found between gestational age and the level of most of the complement components. CH50 and AP50 also showed a positive trend which, however, was not statistically significant. No correlation was found between birthweight and complement activity or complement component levels. The neutrophil bactericidal activity of full-term newborns was about one-third that of adults (P < 0.001). Adult serum improved the bactericidal activity of newborn neutrophils by 93%, indicating a considerable neonatal humoral defect. Conversely, neonatal serum blunted the adult bactericidal activity by 86%. Our results support the fact that both humoral and phagocytic functions in newborn infants are impaired, which may possibly account for their increased tendency to develop severe pyogenic infections.

Adult↗
PubMedDate not supplied

Role of natural killer cells in controlling local tumor formation and metastatic manifestation of different 3LL Lewis lung carcinoma cell clones.

Using two cell clones derived from 3LL Lewis carcinoma; an NK-resistant (designated A6) and an NK-susceptible (designated F2) clone, we investigated the effect of the NK system on local tumor growth and metastasis. Both clones generated local tumors at the inoculation site somewhat faster in NK-deficient (bg/bg) than in normal mice. In addition, these tumors grew slightly faster in the bg/bg mice. However, the effect of the NK system on the metastatic spread of these clones was much more prominent. The F2 cells were profoundly less metastatic than the A6 cells when inoculated into normal mice, whereas in the NK-deficient mice, both clones were highly metastatic. Thus, the NK system appears to be effective primarily in controlling the metastatic spread of the 3LL cells and has a lesser effect on their local tumor formation.

Animals↗
PubMedDate not supplied

A multivariate model to predict the distance from the skin to the epidural space in an obstetric population.

BACKGROUND AND OBJECTIVES: Several attempts to relate epidural space depth to individual patient parameters or details of technique have yielded modest correlations. An attempt has been made to construct a multivariate model to predict the depth from the skin of the epidural space with use of several such factors. METHODS: The depth of the epidural space from the skin was measured in 263 obstetric patients by using calibrated needles. In 53 patients, the angle of insertion of the epidural needle was also measured, with protractors. For each patient, 14 descriptors of patient habitus and anesthetic technique were recorded. Multiple regression analysis was used to construct models incorporating combinations of these variables to predict the epidural space depth; the model balancing the highest correlation coefficient and greatest statistical significance was selected. The validity of the model was tested on the 53 patients in whom the angle of the needle had been measured but whose data have not been used to construct the model. RESULTS: A model containing the seven variables present-weight, height, body mass index, age, parity, interspace, and patient position-yielded r = .689, < .0001. This model predicted the depth of the epidural space to within 8 mm and predicted the depth in the validation group well. Correction for the angle of insertion of the needle did not improve the predictive power of the model. CONCLUSIONS: While this model is the best predictor of epidural space depth yet published, it is probably not sufficiently accurate to be clinically useful in confirming proper epidural catheter placement. Further work in this area is probably not justified.

Anesthesia, Epidural↗