Biomedical subjects
Publications and source records attributed to M Kotb.
Lipoteichoic acid isolated from Streptococcus faecalis or Streptococcus pyogenes caused direct activation of the respiratory burst in human peripheral blood monocytes. This activity appears to be related to the ability of lipoteichoic acid to bind to the monocyte membrane and trigger the polarization of receptors (capping).
Rabbit antisera evoked by type 5 streptococcal M protein (M5) were screened by enzyme-linked immunosorbent assay (ELISA) for immunological cross-reactivity with purified rabbit muscle phosphorylases a and b. Of 10 pep M5 antisera tested, 3 showed significant cross-reactivity with both forms of the enzyme. ELISA inhibition studies using one of the pep M5 antisera showed that all of the phosphorylase b antibodies were inhibited by pep M5, the immunogen, and phosphorylase b, the ELISA antigen. All of the antibodies were also inhibited by pep M6 and pep M19, but not by pep M24, indicating that the cross-reactive epitopes were shared by multiple serotypes of M protein. Western blot (immunoblot) analyses showed that pep M5 antisera reacted strongly with the subunit of phosphorylase b. In addition, purified phosphorylase partially inhibited the binding of pep M5 antibodies to a 95-kilodalton protein of human myocardium. One of the three cross-reactive pep M5 antisera inhibited the enzymatic activity of phosphorylase a in a dose-related fashion, reaching a maximum inhibition of 75%. The enzymatic activity in the presence of antibody was totally restored when the antiserum was first incubated with pep M5.
Purified polypeptide fragments of certain surface M proteins of group A streptococci stimulate blastogenesis and the differentiation of cytotoxic T lymphocytes of normal human lymphocytes. The biochemical basis of lymphocyte stimulation by a type M5 protein polypeptide fragment (pep M5) was investigated. Optimal blastogenic doses of pep M5 or phytohemagglutinin stimulated the phosphorylation of several cellular proteins. However, pep M5 but not phytohemagglutinin induced the phosphorylation of 28- and 35-kDa proteins. The 28-kDa protein was shown to be phosphorylated only at serine residues, whereas the 35-kDa protein was phosphorylated only at tyrosine residues. Stimulation of peripheral blood lymphocytes with pep M5 caused a two-fold increase in the CD8+ and CD4+ 4B4+ subpopulations of T lymphocytes. The phosphorylation of the 28-kDa protein appeared to be confined to the CD4+ T cell subpopulation.
Purified group A streptococcal M proteins, pep M5 and pep M6, bearing heart cross-reactive epitopes were compared with pep M24, which lacks such epitopes, in their ability to induce functional differentiation of human T lymphocytes. Lymphocytes activated by pep M5 and pep M6 demonstrated cytotoxic activity against cultured heart cells, whereas pep M24-activated cells differentiated into suppressor T cells, which specifically blocked cytotoxic T lymphocytes against cultured human myocardial cells and not NK cell activity against K562 cells. Pep M5 and not pep M24 induced an increase in the number of CD4, 4B4, helper/inducer T cells. In addition, these M proteins appear to induce different biochemical changes in T lymphocytes. Both pep M5 and pep M24 induced the phosphorylation of a 35-kDa cytoplasmic protein; however, only pep M5 induced the phosphorylation of a 28-kDa membrane protein, primarily in CD4 T cells. These data indicate that the virulent M protein Ag of group A streptococci may exert their effect on the human immune system via different mechanisms. Determining these mechanisms and the biochemical pathways involved in T cell differentiation triggered by these Ag may be important in understanding the pathogenesis of post-streptococcal diseases.
During a period of 4 years (December 1983-December 1987) 250 children were operated upon by the authors. At the outpatient clinic of the New Children's Hospital 313 infants and children suffering a myelodysraphic lesion were seen, 63 of whom were not treated surgically owing to the presence of severe hydrocephalus in 16 cases and complete flaccid paraplegia with marked sphincteric disturbances in 47. All of the patients came from poor families. Malnutrition, many siblings per family, poor maternal care, and repeated pregnancies and abortions have added to the large incidence of such a handicap in Egypt. The clinical features, diagnosis, and management of 200 cases of spinal bifida aperta (SBA) and 50 of spina bifida occulta (SBO) are summarized. SBA cases were operated upon as soon as possible from the time of their presentation; their preliminary assessment included an exhaustive general, neurological, urological, and orthopedic examination; and investigations such as plain X-rays to the back and skull, CT scanning of the cranium, spinal myelogram, and metrizamide CT scanning to the back were performed. The surgical outcome is far from being satisfactory in the sense of producing an ambulatory, intelligent, healthy individual, especially in a meningomyelocele patient having a high-level lesion. The authors believe that there is still much to be done for these children marked by fate, and the neurosurgeon should be one among several other physicians devoted to the amelioration or at least the prevention of worsening, if possible, of the condition in such unfortunate and handicapped children.
The effects of the specific antigen M5 protein of group A streptococci on AdoMet synthetase activity and AdoMet levels in peripheral blood (PB) lymphocytes were studied and were compared with the effects of the nonspecific polyclonal T cell mitogen PHA. M5 protein stimulated AdoMet synthetase activity, whereas PHA had a biphasic effect with an early inhibitory effect and a later stimulatory effect on AdoMet synthetase activity. S-Carbamyl-L-cysteine (SCC), an inhibitor of human lymphocyte AdoMet synthetase, reduced AdoMet levels and inhibited the blastogenic response of PB lymphocytes to both M5 protein and PHA. Inhibition of the response to M5 protein was stronger than that to PHA. However, the inhibitory effects of SCC were totally reversible by washing the cells. It is our hypothesis that such differences in the biochemical events triggered by specific antigen as opposed to a polyclonal mitogen may determine the direction of the functional differentiation of T lymphocytes.
Although various techniques to determine amputation level have become available, obvious clinical factors may yet identify patients in whom a major amputation is unlikely to heal. We have analyzed the association of multiple clinical factors with the morbidity of 1028 consecutive amputations performed in 786 patients during a 13-year period. The overall operative mortality rate was 7% (57 of 786 patients). Cardiac complications were the leading cause of death (43%). In the 729 patients surviving operation, 345 above-knee amputations (AKAs) and 626 below-knee amputations (BKAs) were performed. After operation, 15.4% of these amputations failed to heal and required proximal revision. The AKA failure rate was 9% and the BKA failure rate was 19%. Significantly higher failure rates were noted in whites, nondiabetics, and those patients with heart disease. It is concluded that major amputation continues to be associated with significant morbidity and mortality rates despite changes in perioperative care and surgical technique. Common clinical characteristics indicate high-risk patients in whom a BKA is unlikely to heal and who may benefit from prospective attempts to determine amputation level.
S-Adenosylmethionine synthetase has been purified to apparent homogeneity from human chronic lymphocytic leukemia cells. Equilibrium sedimentation studies and denaturing polyacrylamide gel electrophoresis indicate that the native enzyme has a molecular weight of 185,000 and a subunit composition of either alpha alpha' beta 2, alpha 2 beta 2, or alpha' 2 beta 2, where alpha, alpha', and beta are polypeptide chains of molecular weight 53,000, 51,000, and 38,000. The alpha and alpha' subunits appear to be the same polypeptide and presumably differ by some kind of post-translational modification. Stoichiometric studies show that the expected products S-adenosylmethionine, pyrophosphate, and orthophosphate are generated in equimolar amounts. The enzyme exhibits linear kinetics with respect to substrate dependency and product inhibition, except for orthophosphate which shows parabolic noncompetitive inhibition with respect to ATP. Initial velocity studies of substrate dependence and product inhibition indicate a steady state mechanism that is ordered Bi Ter with ATP adding before L-methionine and S-adenosylmethionine as the first product released. Pyrophosphate and orthophosphate, however, appear to be released by a random mechanism. Free Mg2+ is an essential activator with a half-maximal effect at 1.0 mM. The Km and Kia for ATP are 31 microM and 84 microM, and the Km for L-methionine is 3.3 microM. The enzyme also has tripolyphosphatase activity which is stimulated by S-adenosylmethionine.
Amputation done on an emergency basis of severely ischemic or infected limbs in critically ill patients frequently results in increased morbidity and mortality. To evaluate the effect of delaying an inevitable operative amputation by a simplified method of freezing the involved extremity, the records of 56 patients who underwent preoperative cryoamputation during a 12-year period were reviewed. Data concerning risk factors, associated medical conditions, local or systemic signs of sepsis, level of amputation, morbidity, and mortality were analyzed. Following cryoamputation of 57 limbs, 16 above-knee amputations (AKA) and 41 below-knee amputations (BKA) were performed. The overall mortality rate associated with cryoamputation was 14% (8 of 57); four postoperative deaths occurred in both the AKA and BKA groups. The mortality rate for 1021 primary operative major amputations during the same period was 7% (p less than 0.04). The only factor identified that significantly affected survival following cryoamputation was diabetes mellitus, which was present in 68% of surviving patients and in 12% of those who died (p less than 0.001). This experience suggests that cryoamputation is a valuable, simple technique that allows for deliberate stabilization and preparation of seriously ill, septic patients prior to surgical procedures, which, when performed on an emergency basis have been associated with mortality rates exceeding 40%.
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Rabbit antiserum to rat peritoneal exudate (PE) macrophage (M phi) antigens was prepared and its reactivity with cell surface proteins of M phi, granulocytes, and lymphocytes was studied by one- and two-dimensional polyacrylamide gel electrophoresis (PAGE). A total of 14 membrane antigens were identified of which three were found to be expressed only by M phi and granulocytes. By one-dimensional analysis, a protein with an approximate m.w. of 105,000 was present on splenic and PE M phi and on splenic lymphocytes. Two-dimensional analysis revealed that this band was heterogeneous and contained at least three species, one of which was restricted to expression on M phi and granulocytes. A second protein of 150,000 daltons was resolved into two species by two-dimensional analysis. Both of these species were present on M phi and granulocytes but not on lymphocytes. Both the 105,000- and 150,000-dalton proteins were glycosylated. Because the 105,000- and 150-000-dalton proteins expressed by M phi were also expressed by granulocytes, is is likely that these are differentiation antigens whose expression is a characteristic property of cells within both monocytoid and myeloid lineages. All three 105,000-dalton species and one of the two 150,000-dalton species were detected on mouse M phi, indicating their expression is not unique to the rat.
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Lung injury is a major cause of patient morbidity in acute pancreatitis. The purpose of this study was to examine the mechanism of pulmonary infiltration and lung injury in acute pancreatitis. Mice were fed a choline-deficient/ethionine-supplemented (CDE) diet for 144 hours to induce severe acute pancreatitis. Serum samples were collected for measurement of biochemical markers of disease and for the detection of tumor necrosis factor-alpha (TNF-alpha). Cell surface adhesion molecule expression was quantified by the sensitive radiolabeled dual monoclonal antibody technique. Neutrophil sequestration in lung tissue was measured by the myeloperoxidase assay. Lung injury was determined histologically and lung edema was assessed by wet/dry ratios. Pancreatic injury was demonstrated to occur in all CDE-fed mice, which developed significant hyperamylasemia and hypoglycemia by 48 hours (P <0.0001). Serum TNF-alpha levels increased significantly by 48 hours over baseline values (P <0.02). Expression of intracellular adhesion molecule (ICAM-1) in pulmonary endothelia was significantly increased above baseline by 30% at 48 hours (P <0.02) and peaked at 120 hours by 100% (P <0.0001). Vascular cellular adhesion molecule (VCAM-1) was constitutively expressed at baseline and was upregulated threefold by 48 hours (P <0.0001). Neutrophil infiltration increased gradually 24 hours after ICAM-1 and VCAM-1 were upregulated with significant elevation of myeloperoxidase activity over baseline at 72 hours (7.2 +/- 1.2 vs. 18.1 +/- 2.2 activity units/gram tissue; P <0.05). Neutrophil infiltration peaked at 144 hours (26.24 +/- 10.49 activity units/gram tissue P <0.0001), and its kinetics correlated with the onset and progression of morphologic injury as well as increased lung edema. These results show that acute pancreatitis is associated with a systemic release of inflammatory cytokines, followed by increased expression of pulmonary ICAM-1 and VCAM-1, neutrophil infiltration, and histologic lung injury. The adhesion molecule axis may be a potential target for practical intervention to ameliorate lung injury and morbidity in acute pancreatitis.
OBJECTIVES: The use of duplex studies for the portal tree has revolutionized the concepts of haemodynamic pathophysiology in the case of portal hypertensive bleeders. The identification of possible haemodynamic patterns in schistosomal bleeders, and the effects of devascularization procedure and distal lienorenal shunts on a selected haemodynamic pattern, are the aim of this work. PATIENTS AND METHODS: Patients (219) with schistosomal hepatic fibrosis and history of bleeding oesophageal varices were studied. The patency, diameter, velocity and flow volume/min in the portal and splenic veins were followed by coloured Duplex. Two matched groups (30 patients each) with the most commonly found haemodynamic pattern (splenic vein flow exceeding portal vein flow) were operated upon. Devascularization procedure was done for the first group (A) and distal splenorenal shunt for the second group (B). RESULTS: Coloured duplex assessment of portal circulation in schistosomal patients identified four haemodynamic patterns. Pattern I (approximately 59%); splenic vein flow exceeds the portal vein flow. Pattern II (approximately 28%); portal vein flow exceeds splenic vein flow. In both patterns, the portal flow was hepatopedal. Patterns III and IV (8% and 5%, respectively) were associated with hepatofugal flow. Splenic vein flow exceeds portal vein flow in pattern III and the reverse in pattern IV. Distal lienorenal shunts done for patients with haemodynamic pattern I was followed by a rebleeding rate of 3.3% while devascularization done for patients with the same pattern was followed by a rebleeding rate of 26.6%. Mild encephalopathy was detected in 10% of patients with distal lienorenal shunts and responded to dietary regulations. CONCLUSIONS: DSRS proved to be ideal for schistosomal patients with hepatopedal flow and splenic vein flow exceeding portal vein flow; since in addition to eliminating the high splenic flow out of portal circulation, it decreased the pressure in the gastroesophageal region. Other patterns with their frequencies and the suggested surgical procedures were also presented.
OBJECTIVE: The effects of the superantigens (SAgs) Staphylococcal Enterotoxin B (SEB), Toxic Shock Syndrome Toxin-1 (TSST-1) and Mycoplasma Arthritidis Mitogen (MAM) were examined on the induction and on the course of experimental SLE-like disease. METHODS: Immunization of BALB/c mice with human anti-DNA mAb (MIV-7) carrying the pathogenic idiotype 16/6 emulsified in complete Freund's adjuvant (CFA), followed by a boost of MIV-7/PBS 3 weeks later, generated an experimental SLE via an idiotypic dysregulation. RESULTS: After immunization with MIV-7/SAg, replacing the MIV-7 boost by SAg, and then injecting SAg 7 weeks after the regular induction of the SLE-like disease, the mice failed to produce anti-hIgM and dsDNA Ab up to 6 months after the induction. The mice immunized with MIV-7/CFA and boosted with the SAg had high titers of anti-hIgM but no detectable anti-dsDNA Ab. In both experimental groups low titers of anti-CL Abs developed in 25/40 (62%) and 30/38 (79%) of the mice respectively, including the control mice immunized with non-pathogenic human IgM/SAg or PBS/SAg. The mice immunized according to the "classical" protocol showed increased titers of anti-dsDNA Ab (22%) and anti-CL Ab (28%) during 10 weeks of observation. In contrast SEB, TSST-1 and MAM induced a 29%, 1% and 17% reduction in the anti-DNA titers and a 32%, 15% and 12% reduction in the anti-CL titers, respectively. CONCLUSIONS: These data suggest that the SAg tested here cannot replace the effect of CFA in the induction of the primary humoral response. The SAgs TSST-1, SEB and MAM did not induce the SLE-like disease following idiotypic modulation. Moreover, they may have had a suppressive effect on the idiotypic network in our model. The appearance of anti-CL Abs in almost all the experimental groups including the naive mice supports the possibility that microbial SAgs can induce the production of autoantibodies by different mechanisms. The SAgs TSST-1, SEB and MAM reduced autoantibody production in the serologically established idiotypic-induced experimental SLE-like murine model. This beneficial effect may indicate new directions for research on the management of SLE.
OBJECTIVE: Management of the impalpable testis often represents a significant diagnostic and therapeutic challenge for the radiologist and surgeon. The aim of this work is to present the superior value of laparoscopy as a single tool for the diagnosis and treatment of the impalpable testis. METHODS AND PROCEDURES: Thirty-three patients with 43 impalpable testes are included in this study. For each patient, magnetic resonance imaging (MRI) then laparoscopy were performed. Either the testis or blind-ending cord structures are searched for. The testis was either brought down to the scrotum or removed depending on the condition of each patient. RESULTS: MRI detected 16 out of 43 impalpable testes (37.2%). Laparoscopy, on the other hand, detected 18 intra-abdominal testes, 7 inguinal and 16 blind-ending cord structures either above or below the internal inguinal ring. Blind-ending cord structures suggested a vanished testis. Orchidopexy was done for 23 cases, orchidectomy in 18 cases and laparoscopy only in 2 cases. CONCLUSION: Laparoscopy seems to offer a safe and reliable diagnostic and therapeutic option to patients with impalpable testes. Intra-abdominal dissection allows more testes to be brought down to the scrotum. The procedure is best viewed as laparoscopy-assisted, as orchidopexy has to be done in a conventional manner.