In vivo detection of single cells by MRI.

The use of high-relaxivity, intracellular contrast agents has enabled MRI monitoring of cell migration through and homing to various tissues, such as brain, spinal cord, heart, and muscle. Here it is shown that MRI can detect single cells in vivo, homing to tissue, following cell labeling and transplantation. Primary mouse hepatocytes were double-labeled with green fluorescent 1.63-microm iron oxide particles and red fluorescent endosomal labeling dye, and injected into the spleens of recipient mice. This is a common hepatocyte transplantation paradigm in rodents whereby hepatocytes migrate from the spleen to the liver as single cells. One month later the animals underwent in vivo MRI and punctuated, dark contrast regions were detected scattered through the livers. MRI of perfused, fixed samples and labeled hepatocyte phantoms in combination with histological evaluation confirmed the presence of dispersed single hepatocytes grafted into the livers. Appropriate controls were used to determine whether the observed contrast could have been due to dead cells or free particles, and the results confirmed that the contrast was due to disperse, single cells. Detecting single cells in vivo opens the door to a number of experiments, such as monitoring rare cellular events, assessing the kinetics of stem cell homing, and achieving early detection of metastases.     

Oral patient-controlled analgesia in adolescents.

Adolescence is a time when concerns about independence and self-control are of paramount importance. These developmental issues must be considered when planning treatment for adolescents with acute or chronic pain. Patient-controlled analgesia (PCA) is a method of administering opioids that reinforces patient autonomy. Traditionally, opioids given by PCA are administered via the intravenous or subcutaneous route. Issues of autonomy and control, however, are no less important for patients receiving oral opioids. To augment patient autonomy, we have provided oral medication kept at the bedside (oral bedside PCA) for adolescents with diverse pain problems. We describe our selection criteria and methods for using oral bedside PCA with adolescents and present 4 patients who used this method.     

Rhabdomyosarcoma. From the laboratory to the clinic

The prospect of identifying and developing new agents for treatment of rhabdomyosarcomas is discussed in the light of current prognosis for children with advanced stage disease. Preliminary attempts to identify tumor-specific agents using in vitro cell culture show potential promise, but as yet remain unproven. The more complex system of identifying therapeutically active agents using human tumor xenografts has demonstrated usefulness. The potential problems associated with this system are discussed.     

Comparison of FK-506 and cyclosporine regimens in pediatric renal transplantation

Clinical aspects of FK-506 or cyclosporine immunosuppression regimens were evaluated in 48 consecutive pediatric renal transplant recipients. Tapering and discontinuation of prednisone was employed only in children receiving FK-506 who experienced minor or no rejection episodes during the 1st posttransplant month. At 1 year follow-up, 17 of 22 (77%) of all children with functioning allografts were receiving no prednisone (n=13) or a mean dosage of 0.07 mg/kg per day (n=4). During the 1st month, acute cellular rejection was more common in the FK-506 group (0.58 vs. 0.21 rejections per patient,P<0.05) but allograft survival (92%) and renal function at 1 year posttransplant were identical in both groups. Compared with the cyclosporine regimen, FK-506 immunosuppression may be associated with a higher incidence of cytomegalovirus or reversible Epstein-Barr virus-induced lymphoproliferative disease. However, the FK-506 group had less hirsutism and gingival hypertrophy and required fewer antihypertensive medications independent of steroid use. Height standard deviation scores and weight-for-height index improved only in preadolescents receiving FK-506 but no prednisone (P<0.02 andP<0.05, respectively), but did not differ between children on FK-506 plus prednisone and those in the cyclosporine group. We conclude that the major advantages of FK-506 over cyclosporine immunosuppression are a reduced severity of hypertension and an improved cosmetic appearance which may improve long-term medical compliance. When used as monotherapy, FK-506 also shows promise in relieving the growth retardation associated with cyclosporine regimens that include prednisone.     

Caffeine and headaches

Neurological Sciences - Caffeine is the most widely consumed psychostimulant drug. It is a potent antagonist of adenosine receptors at dosages consistent with common dietary intake. With infrequent...     

The effect of menstrual cycle on blood alcohol levels and behavior

To determine whether the behavioral effects of alcohol were altered by menstrual cycle phase, 10 women between the ages of 21 and 24 who reported regular menstrual cycles of 28-31 days participated in three experimental sessions, the dates of which coincided with the flow, midcycle and premenstrual phases of their cycles. In each session, the effects of alcohol (.65 g/kg) were measured on memory for words, standing steadiness, coding vigilance and blood alcohol level (BAL). The following measures were obtained in each of three testing rounds: baseline, the ascending limb of the BAL curve and the descending limb of the BAL curve. Peak BALs of 83 +/- 2 mg/d1 were obtained. On coding vigilance, the subjects were observed to perform better during the flow phase of their cycle than they did in either the midcycle or premenstrual phase. No significant phase by alcohol effects were obtained, however. These results suggest that neither the pharmacokinetics of alcohol nor certain behaviors affected by alcohol were affected by menstrual cycle phase. These results are generally consistent with previous research, and they question the logic of excluding women subjects from studies on the effects of alcohol on behavior, at least for the variables used in this study.     

Clonidine-induced suppression of plasma catecholamines in states of adrenal medulla hyperfunction

To assess adrenal medulla activity in states of hyperfunction, a single 0.3 mg oral dose of clonidine hydrochloride (Catapres) was given to twelve patients with varying evidence of familial adrenal medullary hyperplasia and pheochromocytomas from kindreds with Multiple Endocrine Neoplasia type 2 syndrome (MEN-2), seven patients with sporadic pheochromocytomas and six normal subjects. Mean arterial blood pressure and plasma norepinephrine (NE) levels were lower than baseline values 2 h after clonidine in the normal subjects. Plasma epinephrine (E) rose in one normal but fell in the remainder after clonidine administration. In sporadic pheochromocytoma patients, E fell slightly in 4 and NE fell in 3 while mean arterial blood pressure was not significantly lower than baseline values in 7 patients 2 h after clonidine. In MEN-2, mean arterial blood pressure fell and there was a variable response of plasma E and NE to clonidine, which appears to be related to the presence of detectable anatomic (CT scan) and functional (131I-mlBG scintigraphy) abnormalities of the adrenal medulla. These findings are thus compatible with the spectrum of adrenal medulla dysfunction and the presumed development of pheochromocytoma in this syndrome.     

RGD peptides immobilized on a mechanically deformable surface promote osteoblast differentiation.

The major objective of this work was to attach bone cells to a deformable surface for the effective transmission of force. We functionalized a silastic membrane and treated it with 3-aminopropyltriethoxysilane (APTS). A minimal RGD peptide was then covalently linked to the aminated surface. MC3T3-E1 osteoblast-like cells were cultured on the arginine-glycine-aspartic acid (RGD)-treated membrane for 3-15 days and cell attachment and proliferation was evaluated. We observed that cells were immediately bound to the membrane and proliferated. After 8 days on the material surface, osteoblasts exhibited high levels of ALP staining, indicating that the cells were undergoing maturation. Alizarin red staining and Fourier transform infrared (FTIR) analysis showed that the mineral formed by the cells was a biological apatite. The second objective was to apply a mechanical force to cells cultured on the modified silicone membrane. Dynamic equibiaxial strain, 2% magnitude, and a 0.25-Hz frequency were applied to bone cells for 2 h. Osteoblasts elicited increased phalloidin fluorescence, suggesting that there was reorganization of the cytoskeleton. Furthermore, the applied strain elicited increased expression of the alpha(v)beta3 integrin receptor. We concluded that the covalent binding of RGD peptides to a silicone membrane provides a compatible surface for the attachment and subsequent differentiation of osteoblasts. Moreover, the engineered surface transduces applied mechanical forces directly to the adherent cells via integrin receptors.