Non-specific response of serum growth hormone to thyrotropin-releasing hormone in diabetics

It is well known that growth hormone (GE) secretion and regulation in diabetics are abnormal. In order to evaluate the response of GH to nonphysiological stimuli in diabetics, a thyrotropin-releasing hormone (TRH) test (500 micrograms by IV bolus injection) was carried out in 12 patients with insulin-dependent diabetes (IDD, 6 males and 6 females). 11 noninsulin-dependent diabetes (NIDD, 5 males and 6 females), and 10 normal controls (6 males and 4 females). The results showed that the basal serum GH levels in diabetics were higher than that in normal controls and it was even higher in IDD than in NIDD. Following the TRH stimulus, the mean peak level of GH in IDD was the highest among the three groups, the differences being statistically significant (F = 9.323, P less than 0.01). It was concluded that a nonspecific response to TRH of GH did occur in IDD, and the peak values were even higher in female than in male subjects. A negative correlation existed between the GH peak values and the age of the patients as well as in the controls. This supported the view that GH responsiveness to TRH has a tendency of progressive decline with age. However, no significant correlation was found between the peak value of GH and the blood glucose level or the microangiopathic complications. The mechanism of TRH stimulation on GH release in diabetics is discussed.

[Metastatic characteristics of SY86B human gastric carcinoma in athymic nude mice]

The invasive and metastatic behavior of SY86B human gastric carcinoma in nude mice were further studied. The results showed that this human cancer strain had a relatively high spontaneous metastatic rate (68.4%). The metastasis was related to the invasiveness of the transplanted tumor and tumor-bearing time. Since the metastasis developed from 2nd to 9th passages, it was considered that this model had a stable metastatic tendency. It was observed that the genetic background, age and sex difference of the recipient nude mice may not be associated with the metastasis. Aside from the high transplantable rate (100%) and spontaneous metastatic rate (68.4%), SY86B human gastric carcinoma strain still maintains the morphologic, immunologic, genetic and ultrastructural characteristics of the original tumor. All these make it a useful means in the study of diagnosis and treatment of cancer metastasis.

Protective monoclonal antibodies recognize heat-labile epitopes on surface proteins of spotted fever group rickettsiae

Thirty-eight monoclonal antibodies that have not been reported previously were developed from mice immunized with Rickettsia rickettsii, R. conorii, and R. sibirica. Western immunoblotting showed that these monoclonal antibodies are directed against heat-sensitive epitopes which are located on two major surface polypeptides with molecular sizes ranging from 115 to 150 kilodaltons. The detection of the two bands did not depend on the presence of 2-mercaptoethanol. Both bands were destroyed by treatment with proteinase K. Monoclonal antibodies examined by immunofluorescence assay reacted with epitopes that are species specific, group reactive, or shared among a smaller subset of species of spotted fever group rickettsiae. Nine of the monoclonal antibodies were evaluated for their ability to neutralize rickettsial infection and thus protect animals against disease caused by homologous species of rickettsiae. Treatment of rickettsiae with monoclonal antibodies F3-12, F3-14, and F3-36 completely protected guinea pigs against illness caused by the homologous organism R. rickettsii. Monoclonal antibodies F9-5G11 and F15-5B12, derived from mice immunized with R. sibirica, conferred partial protection by delaying the onset and shortening the duration of fever in guinea pigs inoculated with R. sibirica. Monoclonal antibodies F2-15, F2-31, F2-53, and F3-12 protected mice from a lethal infection with R. conorii. Heat-labile epitopes of spotted fever group rickettsial surface proteins are important candidate antigens for development of vaccines to confer protective immunity.

Analogs of unusual sponge phospholipids. Synthesis and thermotropic properties of 1,2-di-(6Z,9Z)-6,9-hexacosadienoyl phosphatidylcholine and phosphatidylethanolamine

The major marine sponge phospholipids 1,2-di-(5Z,9Z)-5,9-hexacosadienoyl phosphatidylcholine (PC) and phosphatidyl-ethanolamine (PE) hardly incorporate cholesterol into their liposomal bilayers, as reported earlier. Our previous studies indicated that their synthetic short chain (C18-C24) analogs with the same double bond pattern readily incorporated cholesterol, thus demonstrating the importance of the chain length. In order to investigate the possible role of the unusual delta 5,9 diunsaturation 1,2-di-(6Z,9Z)-6,9-hexacosadienoyl phosphatidylcholine and phosphatidylethanolamine were synthesized and their thermotropic behavior studied. Both analogs shows a transition endoterm at 45 degrees C, while the natural 1,2-di-(5Z,9Z)-5,9-hexacosadienoyl PC and its PE counterpart exhibited it at 42 degrees C. A partial incorporation of cholesterol into liposomal bilayers of 1,2-di-(6Z,9Z)-6,9-hexacosadienoyl PC was observed. Our results suggest that while the chain length is the predominant factor in the interactions of these phospholipids with sterols, the double bond location may also play a contributing role.

Parallel induction of fibrinolysis and receptors for plasminogen and urokinase by interferon gamma on U937 cells

A new cell sorter technique was employed to study the role of interferon gamma (INF gamma) in fibrinolysis induced by U937 monocytic cells. INF-gamma induced the differentiation of U937 cells as evidenced by the appearance of CD 14 antigen on the cell surface. Scatchard analysis and dose response curves showed a parallel increase in the number of receptors on U937 cells capable of accepting exogenous plasminogen and urokinase (UPA) synthetized by differentiating U937 monocytic cells. This would favour an activation of plasminogen by UPA. This adds a new parameter in the regulation of cell-mediated fibrinolysis and may be important in a number of biological processes.

Invasion and metastasis of SY86B human gastric carcinoma cells in nude mice

A moderately differentiated tubular adenocarcinoma of human stomach, named SY86B, was successfully transplanted subcutaneously to nude mice of different genetic backgrounds (BALB/CA/PBI-nu, C57BL/6J.615/PBI-nu and ICR.BALB/CA/PBI-nu). The tumor has been passaged for 13 generations and the transplantability was 100%. The SY86B cells retained the capacity of invasive and metastatic growth in the nude mice and showed a high rate of metastasis to the regional lymph nodes and to such distant organs as the lungs, liver and pancreas. The overall rate of metastasis was 77.7%. The species of the nude mice, their age and sex apparently did not significantly affect the occurrence of metastasis. Tumor-bearing time and the aggressive character of the tumor cells themselves appeared important for the genesis of metastasis. This experimental model can provide a new approach to basic and clinical studies of cancer metastasis.

Enhanced expression of urokinase activity on U 937 cell line by 1,25-dihydroxyvitamin D3 induction

1,25 Dihydroxyvitamin D3 is a differentiation inducer for monocytic cell. It can induce a monoblastic cell line U937 to differentiate. In this paper, we report that by inducing the differentiation of U937, 1,25-dihydroxyvitamin D3 increased urokinase activity expression on U937 cell surfaces. After incubation of the cell with various concentrations of 1,25-dihydroxyvitamin D3, the cell line showed a remarkable progressively increasing membrane-associated urokinase activity in a dose dependent manner. On the contrary, plasminogen activator inhibitor activity which was found in the culture medium is not modified by the 1,25-dihydroxyvitamin D3 induction. This results suggests another role of 1,25-hydroxyvitamin D3 in the treatment of myelofibrosis, since enhanced plasmin generation can accelerate the activation of procollagenase. The induced plasmin and collagenase activities surrounding the monocytic cells may participate in the physiological and pathological events, especially in the connective tissue degradation.

Barbash strain spotted fever group rickettsia is a strain of Rickettsia conorii and differs from Rickettsia sibirica

The Barbash strain of spotted fever group rickettsia was reexamined in this study by the microimmunofluorescence test with mouse antisera and with monoclonal antibodies. Protein immunoblotting was performed for comparison of purified antigens of R. rickettsii, R. sibirica, R. conorii and Barbash strain. Comparison of Barbash strain, R. rickettsii (Sheila Smith strain), R. conorii (Malish 7 strain), and R. sibirica (strains 232, 246 and Jinghe-74) of the spotted fever group in the microimmunofluorescence test of Philip et al. revealed that Barbash strain has antigens that yield homologous titers with the R. conorii strains and differ from R. sibirica and R. rickettsii. Monoclonal antibodies specific for R. conorii react at identical titres with the Barbash strain, and a monoclonal antibody specific for R. sibirica does not react with the Barbash strain. Likewise, T-cell hybridomas reactive with R. conorii but not R. sibirica yield a strong response when stimulated by Barbash strain antigens. Western immunoblotting with the same polyclonal and monoclonal antibodies confirmed the presence of specific protein antigens of R. conorii and different protein antigenic composition of R. sibirica when compared with Barbash strain. Thus, Barbash strain is a strain of R. conorii.