Human seminal plasma suppresses lymphocyte responses in vitro in serum-free medium

The in vitro immunosuppressive properties of human seminal plasma have been re-investigated in serum-free medium in view of recent suggestions that the previously observed effects might be dependent on the presence of exogenous serum co-factors present in the culture media. The present studies reveal that low concentrations of seminal plasma can inhibit the ability of peripheral blood leukocytes to lyse K562 target cells in the absence of fetal calf or new-born calf serum. These inhibitory effects could be achieved by pre-incubating the effector cells in seminal plasma at 37 degrees C prior to use in the natural killer cell assay or by incorporating it into the assay system. Additional studies revealed that human seminal plasma could also inhibit the proliferative response of peripheral blood lymphocytes to phytohaemagglutinin in serum-free HB103 medium. These effects were most marked and consistent if the seminal plasma was present throughout the period of culture. Overall, these studies indicate that the previously reported suppressive effects of human seminal plasma in these systems cannot be entirely attributable to cytotoxic factors generated by exogenous serum components.     

Echocardiogram‐gated multislice spiral CT in functionally univentricular heart following long‐lasting Waterston–Cooley anastomosis

Waterston–Cooley anastomosis may be carried out in patients with tricuspid atresia to provide pulmonary perfusion. It is associated with several complications, including preferential blood flow to the right lung, hypoplasia of the left pulmonary artery, obstruction of the anatomosis or rupture of pulmonary aneurysms. We study a patient with thrombosis in the pulmonary arteries following surgical construction of a Waterston shunt in childhood. Imaging findings and clinical symptoms are discussed with emphasis on echocardiogram‐gated multislice spiral CT.     

Brain regions involved in prospective memory as determined by positron emission tomography

Prospective memory (PM) refers to the functions that enables a person to carry out an intended act after a delay. Despite the ubiquity of this behaviour, little is known about the supporting brain structures and the roles that they play. In this study, eight healthy participants performed four different PM tasks, each under three conditions: a baseline, and two conditions involving an intention. In the first of the intention conditions, subjects were asked to make a novel response to a certain class of stimuli whilst performing an attention-demanding task. However, the expected stimuli never actually occurred. In the second intention condition subjects were expecting to see these stimuli as before, and they did occur on approximately 20% of trials. Relative to the baseline condition, increases in regional cerebral blood flow (rCBF) as estimated by oxygen-15 positron emission tomography technique across all four tasks were seen in the frontal pole (Brodmann's area 10) bilaterally, right lateral prefrontal and inferior parietal regions plus the precuneus when subjects were expecting a PM stimulus regardless of whether it actually occurred. Further activation was seen in the thalamus when the PM stimuli occurred and was acted upon, with a corresponding rCBF decrease in right lateral prefrontal cortex. It is argued that the first set of region play a role in the maintenance of an intention, with the second set involved additionally in its realisation.     

Interval between insulin injection and breakfast in diabetes

The relationship between the insulin-breakfast interval, postprandial increase in blood glucose, and glycaemic control was studied in 58 children with diabetes. Patients recorded insulin-breakfast intervals in a home diary over a seven day period, and during a 24 hour period at the weekend provided eight serial capillary dried blood spots for glucose analysis. The highest mean blood glucose value occurred two hours after breakfast and showed a significant correlation with fructosamine concentrations. Weekend insulin-breakfast intervals ranged from 2-30 minutes, with 70% reporting intervals of less than 15 minutes. There was a significant correlation between the weekend insulin-breakfast interval and the after breakfast increase in blood glucose with a mean increment of 0.4 mmol/l in the 30 minute group and 7.2 mmol/l in the 2 minute group. Over the whole study period, children with mean insulin-breakfast intervals of two to 12 minutes had a mean fructosamine concentration of 376 mumol/l compared with 341 mumol/l in those with intervals of 15-35 minutes. This study has shown that the interval between insulin injection and breakfast significantly influences the morning postprandial rise in blood glucose and consequently short term glycaemic control. It is therefore important that patients are encouraged to leave an interval of about 30 minutes between insulin injection and breakfast.     

Colorectal hemangioma: radiologic findings

The authors correlated radiographs with the clinical and histologic data of 12 patients with colorectal hemangioma. All patients presented with rectal bleeding, which was chronic in seven. Phleboliths were also visible in seven cases, which correlated with chronic bleeding in five. On barium studies, three masses were soft and three produced rigid narrowing. The atypical features of rigid luminal narrowing, which might mimic a carcinoma, and hypovascularity correlated with chronic bleeding or visible phleboliths, which suggest the correct diagnosis of colorectal hemangioma.     

Early human thymocyte proliferation is regulated by an externally controlled autocrine transforming growth factor-beta 1 mechanism

Early thymocytes undergo extensive proliferation after their entry into the thymus, but cellular interactions and cytokines regulating this intrathymic step remain to be determined. We analyzed the effects of various T-cell growth factors and cellular interactions on in vitro proliferation of early CD2+CD3/TCR-CD4-CD8- (triple negative [TN]) human thymocytes. Freshly isolated TN cells were then assayed for their growth capacity after incubation with CD2I+III-monoclonal antibody (MoAb), recombinant human interleukin-2 (IL-2), IL-7, and/or IL-4. These cells displayed significant proliferative responses with IL-4, IL- 7, or CD2-MoAb+IL-2. The addition of recombinant transforming growth factor beta (TGF beta) or autologous irradiated CD3+CD8+CD4- cells to TN cell cultures dramatically decreased their growth responses to IL-2 and IL-7, whereas IL-4-induced proliferation was less sensitive to growth inhibition. We thus asked whether the CD8+ cell-derived inhibitory effect was due to TGF beta. The addition of neutralizing anti-TGF beta MoAb completely abolished CD8+ cell-derived inhibition of TN cell growth. Analysis of CD8+ cell-derived supernatants indicated that these cells had low TGF beta 1 production capacity, whereas TN cells secrete significantly high levels of TGF beta 1. Cell fixation studies showed that TN cells were the source of the TGF beta. TGF beta 1 released from TN cells was in the latent form that became the active inhibitory form through interaction of TN cells with CD8+ cells. Together, these data suggest a role for TGF beta 1 as an externally controlled, autocrine inhibitory factor for human early thymocytes, with a regulatory role in thymic T-cell output.