Residual beta-cell function in type II diabetes and evaluation of the hepatic insulin extraction

Insulin and C-peptide (free insulin and C-peptide in insulin-treated patients) were measured after glucose stimulation in nine Type II diabetics on chlorpropamide, eleven insulin-treated maturity-onset diabetics and in 8 normal controls. Dissociation between C-peptide and insulin response to glucose was observed in several diabetics. The relation between incremental molar areas under C-peptide and insulin curves, after glucose challenge (delta CPR - delta IRI/delta CPR) were used to evaluate the hepatic insulin extraction in all but the insulin-treated diabetics. The lower insulin requirements and better control of the short-duration insulin-treated maturity-onset diabetics in relation to the long-term ones could not be explained either by the residual insulin secretion or by the level of "insulin antibodies". The chlorpropamide-responsive patients presented higher insulin levels after the glucose challenge and a lower hepatic insulin extraction than the non-responsive ones.     

Respiratory depression produced by centrally administered taurine in the cat

The effects of taurine (0.8-64.8 mumol) were studied on respiratory activity following intracisternal (cisterna magna) and intracerebroventricular (lateral ventricle) injections in cats anesthetized with alpha-chloralose. Respiratory activity was measured by using a Fleisch pneumotachograph and monitoring tracheal airflow. The flow signal was integrated to obtain tidal volume (VT) and respiratory rate (f) was obtained by counting the number of VT excursions over one minute. Inspiratory (TI), expiratory (TE) and total (TTOT) cycle durations were also determined during this time period. In addition, end-tidal CO2 was continuously monitored. Associated changes in arterial pressure (femoral artery cannula) and heart rate were also determined. After injections into the cisterna magna, taurine caused dose-related decreases in minute ventilation (VE). The maximal decrease in VE was from 495 +/- 59 to 64 +/- 14 ml/min (p less than 0.05), and was due to both decreases in VT (from 27 +/- 3 to 5 +/- 1 ml; p less than 0.05) and f (from 18 +/- 1 to 12 +/- 2 breaths/min; p less than 0.05). TE and TTOT were increased from 2.4 +/- 0.4 to 4.5 +/- 0.6 sec (p less than 0.05) and from 3.7 +/- 0.4 to 6.4 +/- 0.8 sec (p less than 0.05), respectively. Mean inspiratory flow (VT/TI), a measure of inspiratory drive, was decreased from 21 +/- 4 to 4 +/- 2 ml/sec (p less than 0.05). Apnea occurred in 5 of 6 animals after the 64.8 mumol dose. This respiratory depression occurred without any significant change in arterial pressure. After lateral ventricle injections, taurine also caused dose-related, but not as pronounced, decreases in respiratory activity. In addition, taurine caused significant decreases (p less than 0.05) in arterial pressure in doses that decreased VE. Taurine administered intravenously had no significant cardiorespiratory depressant effects. These data indicate that centrally administered taurine produces respiratory depression and, depending on the route of CNS administration, also produces hypotension.     

Phagocytosis of bacteria by human leukocytes measured by flow cytometry

A new method has been developed for the evaluation of the phagocytic activity of human leukocytes using fluorescently labeled bacteria and flow cytometry. By simultaneous measurement of cellular light scatter and fluorescence, extracellular bacteria, phagocytes, and nonphagocytes could be discriminated and quantified. All leukocytes assumed to be capable of phagocytosis were phagocytosing, and about 90% of these cells were polymorphonuclear neutrophilic granulocytes. Within 15 min 85% of the bacteria were phagocytosed and each phagocyte contained an average of 15-20 bacteria. The phagocytic capacity of the leukocytes from healthy individuals showed minor interindividual and day-to-day variations. This method facilitates a rapid and accurate in vitro evaluation of the phagocytic activity of human leukocytes.     

Effect of temperature on drought resistance and growth of cotton plants

In cotton plants ( Gossypium hirsutum L. cv. B.J.A.) the temperature of the roots affected both root and shoot growth, as did the temperature of the shoot. Drought resistance increased when the temperature imposed on roots (27°C) was lower than that imposed on shoots (17°C); the result was a decrease in both transpiration and flow of root sap. Stomatal characteristics as measured by density, index and resistance, depended only on shoot temperature. Differences in drought resistance, depended only on shoot temperature. Differences in drought resistance seem to be a result of changes in transpiration flow modulated by the amount of absorbed water.     

Inhibition of the graft-versus-host response by BCGcw-induced suppressor cells or prostaglandin E1

Immunization of C57BL/6 mice with BCGcw stimulated a population of "suppressor cells" which had a decreased capacity to induce the graft-versus-host response. The graft-versus-host response was quantitated using the Simonsen splenomegaly assay. F1 mice (C57BL/6 X CBA) were inoculated intraperitoneally with 1 X 10(8) parental (C57BL/6) or (CBA) spleen cells. The F1 mice were sacrificed 13 days later and the resulting splenomegaly was 3-4 times the normal amount. F1 mice which were injected with parental BCGcw-primed C57BL/6 spleen cells had a 50% inhibition of splenomegaly, whereas BCGcw-primed CBA spleen cells (a strain which does not develop suppressor cells) did not show this inhibition. In vitro results also confirmed that only C57BL/6 mice and not CBA mice developed suppressor cells after BCGcw immunization. A second study showed that X-irradiated (1000 R) BCGcw-primed "suppressor cells" could inhibit splenomegaly caused by the inoculation of normal parental C57BL/6 cells into F1 mice. The mechanism by which BCGcw-primed "suppressor cells" caused this inhibition of splenomegaly was delineated and found to be dependent upon the secretion of prostaglandin (PGE-1). Indomethacin and aspirin, potent inhibitors of prostaglandin synthesis, blocked the activity of C57BL/6 BCGcw "suppressor cells" and splenomegaly resulted. Systemic administration of the prostaglandin (15S)-15-methyl PGE-1 reduced splenomegaly approximately 50% in F1 mice which were injected with C57BL/6 or CBA cells. These results indicated that immunization with BCGcw stimulated a population of "suppressor cells" which could cause a decrease in graft-versus-host response and that the secretion of prostaglandin was responsible for this inhibition.     

Cerebrospinal fluid-contacting neurons of the central canal and terminal ventricle in various vertebrates

Cell and Tissue Research - Cerebrospinal fluid (CSF)-contacting neurons were studied by means of electron microscopy in the spinal cord and/or terminal ventricle of the ray, Raja clavata...     

Penetration of Bdellovibrio bacteriovorus into Host Cells

Electron microscopy reveals that, in Bdellovibrio infection, after the formation of a passage pore in the host cell wall, the differentiated parasite penetration pole is associated with the host protoplast. This firm contact persists throughout the parasite penetration and after this process is completed. In penetrated hosts this contact is also apparent by phase microscopy. The association between the walls of the parasite and the host at the passage pore, on the other hand, is transient. Bdellovibrio do not penetrate hosts whose protoplast and cell walls are separated by plasmolysis, or in which the membrane-wall relationship is affected by low turgor pressure. It is concluded, therefore, that for penetration to occur it is essential that the host protoplast be within reach of the parasite, so that a firm contact can be established between them. A penetration mechanism is proposed that is effected by forces generated by fluxes of water and solutes due to structural changes in the infected host envelope. These forces cause a differential expansion of the host protoplast and cell wall and their separation from each other around the entry site, while the parasite remains firmly anchored to the host protoplast. Consequently, the parasite ends up enclosed in the expanded host periplasm. The actual entry, therefore, is a passive act of the parasite.     

Immunologic and clinical improvement of progressive coccidioidomycosis following administration of transfer factor

Three patients with progressive coccidioidomycosis were given preparations of transfer factor (TF). Adverse reactions to TF were minimal. Following TF administration two of these patients had prolonged clinical remissions in their coccidioidal disease. Cellular immune responses were sequentially evaluated by coccidioidininduced delayed-type skin tests, lymphocyte blast transformation and macrophage inhibition factor production (MIF). These three patients each exhibited different cellular immune patterns before and after TF administration. Two patients converted their coccidioidin skin tests, and one converted lymphocyte transformation response to coccidioidin. Also, TF apparently favorably affected the MIF response in all three patients.