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Biomedical subjects

S R Targan

Publications and source records attributed to S R Targan.

126 records · Page 7Linked to original sources
PubMed1983

Identification of human natural killer soluble cytotoxic factors (NKCF) derived from NK-enriched lymphocyte populations: specificity of generation and killing.

Activated natural killer (NK) cells were induced by stimulation of normal peripheral blood lymphocytes with a B cell line for 5 days or by interferon activation for 1 hr. They were enriched for large granular lymphocytes (LGL) by separation on Percoll density gradients. Supernatants were obtained from incubation mixtures of LGL and NK-sensitive target cells (MOLT-4 or K562). Although some lysis could be detected at 16 hr, optimal NK-sensitive target cell lysis by this supernatant was evident after 40 hr incubation by using a microcytotoxicity assay and trypan blue exclusion. Supernatants derived by co-culture of NK targets with either NK-depleted cell populations or NK cells alone were not cytolytically active. Target cell requirements for both the generation and cytotoxic activity of NKCF were specific. That is, only the NK-sensitive target cells MOLT-4 and K562, and not the NK-resistant cells YAC-1, EL4, IM9, and Raji, could induce release of, or be lysed by, NKCF. Furthermore, the requirement for both Ca2+ and Mg2+ in the generation of NKCF suggests that both target cell binding and initiation of programming for lysis are required for its release. NKCF lytic potential was stable for 2 mo at -20 degrees C and partially stable at 60 degrees C. NKCF activity could be substantially removed by prior absorption on the NK-sensitive target cells, K562 or MOLT-4, but not Raji or IM9 (resistant) cells. Therefore, it appears that the specificity of this cellfree lytic factor depends on its recognition of, or its being recognized by, appropriate target cells. The properties of NKCF will enable the study of the mechanism involved in the lethal hit of NK cell-mediated cytotoxicity.

Calcium↗
PubMed1983

Definition of a "trigger" stage in the NK cytolytic reaction sequence by a monoclonal antibody to the glycoprotein T-200.

The monoclonal antibody 13.1 recognizes an epitope on the T-200 glycoprotein and blocks natural killer (NK) lysis of the erythroleukemia target K562, but not of the acute lymphoblastic leukemia T cell target Molt-4. The inhibitory effect is at the killer cell level and not the target cell level, which suggests that 13.1 may react with a receptor on NK cells. This hypothesis was tested in assays to delineate precisely where in the NK cytolytic reaction sequence 13.1 interferes with lysis; 13.1 did not block initial NK-target cell interaction as measured in a target binding cell assay. With the use of a Ca++ pulse technique, 13.1 did not block any events occurring during Ca++-dependent programming. If the antibody was added after conjugate formation but before the addition of CaCl2 to initiate programming, however, full inhibition of NK lysis occurred. Therefore, 13.1 antibody defines a distinct stage in the NK reaction sequence that links target binding to the initiation of calcium-dependent programming events. NK cell binding alone is not sufficient to trigger lytic events, and the presence of a second structure or a distinct portion on a single structure is required to trigger lysis. We show that 13.1 blocks the ability of K562 to inhibit NK killing of Molt-4 in a cold target inhibition assay. Therefore, despite the fact that 13.1 does not disrupt conjugate formation, NK specificity may exist at a post-binding site rather than at the initial NK-target binding interaction. Our data suggest that the T-200 glycoprotein on NK cells triggers the initiation of the lytic events.

Antibodies, Monoclonal↗
PubMed1982

Characterization of the cytolytic reaction mechanism of the human natural killer (NK) lymphocyte: resolution into binding, programming, and killer cell-independent steps.

Various parameters of the cytolytic reaction mechanisms of the human natural killer (NK) lymphocyte were studied to characterize the lytic cycle. NK cytolysis was determined to occur in three definable steps. 1) Binding of PBL to the NK-sensitive targets Molt-4 or K562 was rapid (less than 1 min), occurred at temperatures below 37 degrees C, was Mg++3-dependent, Ca++3-independent, and was prevented by dispersion of the cells into 10% dextran. 2) Subsequent to binding, programming for lysis as determined by a Ca++ pulse method was more protracted, requiring up to 2 hr to occur and was strictly dependent on Ca++ for cytolysis to proceed. In standard cytotoxicity assays, however, programming for lysis was more rapid occurring in 10 to 30 min. Programming was inhibited by EDTA, EGTA/Mg++ and by temperatures below 37 degrees C. Furthermore, after binding but in the absence of initiation of programming for lysis, the frequency of target binding cells did not change and the NK cell did not lose its lytic potential. 3) Killer cell-independent cytolysis (KCIL) was determined by the addition of EDTA to "programmed" targets and dispersion of these cells into dextran-containing medium, which resulted in virtually 100% dissociation of conjugated cells. KCIL was Ca++ and Mg++-independent and was blocked at reduced temperatures only if the dextran was prechilled to 4 degrees C before addition. The kinetics of 51Cr release during KCIL was rapid and complete 30 min after dispersion. Interferon-activated NK cells expressed an increased rate of cytolysis in Ca++ pulse experiments. This was due to an increased rate of the Ca++-dependent step(s) during the programming events. The rate of the Ca++-independent steps, however, were similar with control and IFN-activated cells.

Calcium↗
PubMed1981

The dual interaction of prostaglandin E2 (PGE2) and interferon (IFN) on NK lytic activation: enhanced capacity of effector-target lytic interactions (recycling) and blockage of pre-NK cell recruitment.

In this study we addressed the question of whether the known NK activators prostaglandin E2 (PGE2) and interferon (IFN) can synergistically activate NK lysis and whether they potentiate the same or different subsets of NK cells. We demonstrated that the activation of NK lysis can be enhanced as well as blocked by the interaction of these 2 activators. The enhancement of activation was not due to recruitment of separate subsets of pre-NK cells, but rather the synergistic enhancement of the recycling capabilities of the same set of NK cells. There was a temporal relationship to this enhancement. That is, if PGE2 was added during cellular processing required for full expression of NK activation induced by IFN, pre-NK lytic potential was inhibited. If, on the other hand, PGE2 is added after completion of full expression of the IFN-induced activated lytic process, there is enhancement of recycling capabilities of the same number of NK cells.

Cytotoxicity, Immunologic↗
PubMed1977

Role of anaerobic bacteria in spontaneous peritonitis of cirrhosis: report of two cases and review of the literature.

The role of anaerobic or microaerophillic bacteria in spontaneous peritonitis of cirrhosis has not been clearly defined. Among 126 cases recorded in the literature, in only eight (6 per cent), including the two reported here, was bacterascites associated with anaerobic or microaerophilic bacteria. Clinical features in these cases were indistinguishable from those associated with aerobic bacteria. However, polymicrobial bacterascites occurred in four of eight cases associated with anaerobes, as contrasted with only 10 of 118 cases (8 per cent) associated with aerobes alone. On the other hand, concurrent bacteremia occurred in only one of eight cases associated with anaerobes as contrasted with 52 of 118 cases (44 per cent) of aerobic spontaneous peritonitis. Experimental evidence is cited in an attempt to explain this relatively low incidence of spontaneous peritonitis associated with anaerobic or microaerophilic bacteria, despite the high density of these organisms in the normal bowel flora.

Adult↗
PubMed1977

Campylobacter fetus associated with pulmonary abscess and empyema.

An unusual case of community-acquired necrotizing aspiration pneumonia with pulmonary abscess and empyema associated with Campylobacter fetus (formerly Vibrio fetus) in mixed culture is reported. This microaerophilic gram-negative curved bacillus has been increasingly associated with human disease. Unlike most pathogens associated with community-acquired aspiration pneumonia, this organism is usually resistant to penicillin. Infection associated with this organism is characteristically relapsing in nature and requires protracted antimicrobial therapy.

Adult↗
PubMed1976

Spontaneous peritonitis of cirrhosis due to Campylobacter fetus.

An unusual case of spontaneous peritonitis of cirrhosis associated with Campylobacter fetus is reported. This microaerophilic gram-negative bacillus has been increasingly associated with human disease recently, particularly in patients with cirrhosis. The infection is characteristically relapsing in nature and requires protracted antimicrobial therapy.

Alcoholism↗
PubMed1976

Hyperamylasemia associated with gonococcal salpingitis and perihepatitis.

A case of hyperamylasemia associated with gonococcal salpingitis and perihepatitis (Fitzhugh-Curtis syndrome) is reported. Other potential causes of hyperamylasemia such as pancreatic, parotic, biliary, or intestinal disease were carefully excluded. In addition, the amylase to creatinine clearance ratio was within normal limits, suggesting tubal rather than pancreatic source of hyperamylasemia. This finding is of clinical importance since acute salpingitis is a prevalent disease and its initial presentation may mimic acute pancreatitis or other causes of surgical abdomen. The amylase to creatinine clearance ratio is of value in differentiating such cases from those with hyperamylasemia due to pancreatitis.

Acute Disease↗
PubMed1975

Dilantin-induced disseminated intravascular coagulation with purpura fulminans. A case report.

A patient developed disseminated intravascular coagulation with purpura fulminans 1 month after starting Dilantin therapy for a seizure disorder. In addition, the patient developed exfoliative dermatitis, hepatitis, cutaneous vasculitis, and microangiopathic hemolytic anemia. She was successfully treated with adrenal steroids and heparin for her purpura fulminans. The hepatitic dermatologic, along with hemorrhagic, complications of Dilantin are reviewed, and the possible origin of the vasculitis and disseminated intravascular coagulation is discussed.

Adolescent↗
PubMedDate not supplied

Additional evidence of linkage between Crohn's disease and a putative locus on chromosome 12.

PURPOSE: The inflammatory bowel diseases (IBD), Crohn's disease (CD), and ulcerative colitis (UC) are chronic intestinal disorder of unknown etiology. Genetic factors play an important role in the pathogenesis of these diseases, but with a complex pattern of inheritance. A number of genome-wide scans have identified several putative susceptibility loci for both CD and UC, including a locus on chromosome 12 reported in a set of British families. We aim to evaluate the linkage between CD or UC and this chromosome 12 locus in an independent set of U.S. Caucasian families (36% being of Ashkenazi Jewish origin). METHODS: Microsatellite markers along chromosome 12 spaced at approximately 10 cm intervals were used to test the putative loci in CD only families (65 sib pairs from 46 families). Regions with positive linkage for CD were then tested in a panel of UC and mixed families (44 sib pairs from 29 families). Two point linkage analysis was performed with SIBPAL. Multipoint linkage analysis was carried out with MAPMAKER/SIBS. RESULTS: We observed evidence of linkage between the region on chromosome 12 and Crohn's disease, because there was a significant excess of allele sharing in CD sib pairs (pi = 0.62, p = 0.0004 from two-point linkage; and logarithm of the odds score (LOD) = 2.0 from multipoint linkage). However, we did not observe the same linkage in UC and mixed families (p = 0.48; not significant [ns]). CONCLUSION: Our data provided further evidence that the region on chromosome 12 is likely to contain a gene predisposing to CD.

Adolescent↗
PubMedDate not supplied

Measurement of tumor necrosis factor alpha mRNA in small numbers of cells by quantitative polymerase chain reaction.

We have developed a method to quantitate TNF alpha-mRNA in small numbers of cells by reverse transcription followed by competitive polymerase chain reaction (RT-PCR). RT-PCR allowed the accurate quantitation of TNF alpha-mRNA over a 1000-fold range of concentration. The recovery of RNA isolated from 1000 to 10,000 cells was optimized by reducing sample volumes and by adding 1 microgram yeast RNA. Using these modifications we accurately measured TNF alpha-mRNA in as little as 10,000 U937 cells by RT-PCR. Then we measured TNF alpha-mRNA in lamina propria mononuclear cells isolated from uninflamed and inflamed colonic mucosa from patients with inflammatory bowel disease (IBD). A 9-fold increase (5.4 copies per cell) was found in mononuclear cells from the gut of the inflamed regions compared to those cells from the uninflamed regions (0.6 copies per cell). These findings demonstrated the utility of this method in measuring differences of expression of the TNF-alpha gene in small number of cells isolated from tissues.

Base Sequence↗