Involvement of amino acid residues 423-429 of human protein S in binding to C4b-binding protein

Human protein S binds to C4b-binding protein (C4BP) both in plasma and in a system using purified proteins. Amino acid residues 420-434 of the first disulfide loop of the sex hormone binding globulinlike domain of protein S are involved in the interaction of protein S with C4BP. To define the involvement of specific polar amino acids within residues 420-434, we studied in parallel synthetic protein S peptides and recombinant protein S variants containing the same amino acid replacements, K423E, E424K, Q427E and K429E. Synthetic peptide analogs of peptide PSP-420 (residues 420-434) were assayed for binding C4BP and as inhibitors of complex formation. The PSP-420 peptide and the analogous peptide with the substitution E424K, but not the peptides containing the substitutions K423E and K429E, were able to bind C4BP. Recombinant proteins with mutations of K423E, Q427E and K429E showed reduced affinity for C4BP compared to plasma protein S, recombinant wild type protein S, or E424K-protein S. These results suggest that Lys-423, Gln-427 and Lys-429 of protein S are important for normal binding to C4BP. The anti-protein S monoclonal antibody LJ-56, raised against peptide PSP-420, recognizes only free protein S and inhibits complex formation with C4BP. Antibody LJ-56 recognized the E424K and Q427E peptides but not the K423E or K429E peptides. Similarly, the E424K and Q427E protein S mutants were recognized by LJ-56, whereas the K423E and K429E protein S mutants were not recognized. This suggests that both in the peptide PSP-420 and in protein S, Lys-423 and Lys-429 significantly contribute to binding to antibody LJ-56. These results demonstrate that protein S residues 423, 427 and 429, but not residue 424, are involved in binding to both the antibody LJ-56 and to C4BP. When peptides PSP 420 and SL-6 (residues 447-460) with carboxyterminal amide or carboxylate moieties were compared to their ability to inhibit C4BP-protein S complexation, PSP-420-amide was the most potent. This finding together with the other results described here supports the hypothesis that the residues 420 and 434 in protein S provides a major binding site for C4BP.     

Love and dating experience in early and middle adolescence: grade and gender comparisons

The experience of being "in love" was studied in a sample of 186 early to middle adolescent males and 199 early to middle adolescent females. Results indicated that amount of dating experience of adolescents varied widely at each age. Being "in love" co-occurred with a reciprocal on-going relationship about half the time. Boys fell in love earlier and more often than girls, and both genders seemed to employ an increasingly narrow prototypical conception of being "in love". Qualitative analyses suggested that early and middle adolescents are actively reasoning about the nature and meaning of romantic feelings and experiences. Results are interpreted from the standpoint of psychosocial developmental theory, and implications for interventions with adolescents are discussed.     

The role of JNK and p38 MAPK activities in UVA-induced signaling pathways leading to AP-1 activation and c-Fos expression

To further delineate ultraviolet A (UVA) signaling pathways in the human keratinocyte cell line HaCaT, we examined the potential role of mitogen-activated protein kinases (MAPKs) in UVA-induced activator protein-1 (AP-1) transactivation and c-Fos expression. UVA-induced phosphorylation of p38 and c-Jun N-terminal kinase (JNK) proteins was detected immediately after irradiation and disappeared after approximately 2 hours. Conversely, phosphorylation of extracellular signal-regulated kinase was significantly inhibited for up to 1 hour post-UVA irradiation. To examine the role of p38 and JNK MAPKs in UVA-induced AP-1 and c-fos transactivations, the selective pharmacologic MAPK inhibitors, SB202190 (p38 inhibitor) and SP600125 (JNK inhibitor), were used to independently treat stably transfected HaCaT cells in luciferase reporter assays. Both SB202190 and SP600125 dose-dependently inhibited UVA-induced AP-1 and c-fos transactivations. SB202190 (0.25-0.5 microM) and SP600125 (62-125 nM) treatments also primarily inhibited UVA-induced c-Fos expression. These results demonstrated that activation of both JNK and p38 play critical role in UVA-mediated AP-1 transactivation and c-Fos expression in these human keratinocyte cells. Targeted inhibition of these MAPKs with their selective pharmacologic inhibitors may be effective chemopreventive strategies for UVA-induced nonmelanoma skin cancer.     

Mammography grid performance

PURPOSE: To measure directly the grid performance of mammography units for the range of breast thicknesses and x-ray tube potentials encountered in clinical practice. MATERIALS AND METHODS: Contrast improvement factors and Bucky factors were determined for four mammographic units as a function of x-ray tube potential (25, 30, and 35 kVp), phantom thickness (2, 4, and 8 cm) and, on one unit, three target-filter combinations. Three units used a linear grid; one, a cellular grid. Two methods were used for nongrid measurements. RESULTS: For all units tested, contrast improvement factor increased with increased phantom thickness and with increased kilovolt peak level for the 8-cm-thick phantom and changed little with kilovolt peak level for 2- and 4-cm-thick phantoms. At 25 and 30 kVp, contrast improvement factor performance with the linear grids was comparable; with the cellular grid, it was 5%-10% higher. In all cases, the Bucky factor increased with increased phantom thickness and decreased with increased tube potential. CONCLUSION: Differences in grid performance exist. At 25 and 30 kVp, the cellular grid exhibited superior contrast improvement factor performance, whereas one of the linear grids exhibited superior Bucky factor performance. Measured contrast improvement and Bucky factors are dependent on nongrid technique. Cassette tunnels introduce scatter and should not be used with nongrid or magnification techniques.     

Cerebral edema in acute hepatic failure: clinicopathologic correlation

A child developed acute fulminant viral hepatitis and cerebral edema confirmed on postmortem examination. Clinical evidence of herniation, effacement of cortical sulci on computed tomography, and elevated cerebrospinal fluid pressure preceded complicating terminal events, demonstrated that cerebral edema was associated with acute hepatic failure, rather than complicating factors, and led to the patient's death. The mechanism is unknown.     

Effects of halothane anesthesia on the motility of the sphincter of Oddi and transsphincteric flow in Australian brush-tailed possums

We evaluated the effect of halothane anesthesia on the motility of the sphincter of Oddi and simultaneous transsphincteric flow in Australian Brush-tailed possums (Trichosurus vulpecula). Halothane levels in the range of 0.25 to 2% were administered and decreased transsphincteric flow in a dose-dependent manner. Sphincter of Oddi basal pressure was higher than normal, but not in a dose-dependent manner. Additionally, halothane anesthesia influenced the sphincter of Oddi motility by decreasing the motility index (mean amplitude multiplied by frequency of contractions). This decrease was dose dependent. These findings indicate that sphincter of Oddi basal pressure is a major component of sphincter of Oddi motility responsible for regulating transsphincteric flow in this species. For studies of the sphincter of Oddi motility in anesthetized Australian Brush-tailed possums, we recommend anesthetic induction with ketamine (50 mg/kg, i.m.) and the inspired halothane level should not exceed 0.75% during the study period, as the effects we have demonstrated were most evident at levels greater than 0.75%. If higher halothane levels are required to maintain satisfactory anesthesia, an alternative anesthetic agent should be considered.     

Proteinuria due to suboptimal hydration with high-dose methotrexate therapy

One of the major complications after high-dose methotrexate (HDMTX) infusions is renal damage. We investigated the occurrence of proteinuria after HDMTX administration in children with pediatric malignancies (acute lymphoid leukaemia, osteosarcoma Burkitt's lymphoma). In the period 1989-1990 we gave 52 HDMTX courses to 24 children. During this period, prehydration and extra urinary alkalisation were performed only if the urinary specific gravity was over 1010 or if the urinary pH fell below 7. Using this schedule the mean values obtained for protein extraction were: before the therapy, 0.12 +/- 0.03 g/m2; on day 1 after MTX treatment, 0.38 +/- 0.06 g/m2; and on day 2 after the MTX infusion, 0.39 +/- 0.11 g/m2 (P < 0.01). A significant increase in proteinuria (> 0.2 g/m2 post- vs pretreatment) was detectable in 54% of the patients. In the period 1991-1992 we modified the hydration-alkalisation schedule to include i.v. prehydration for 18-24 h at 3 l/m2/day with a 0.45% NaCl-5% glucose solution along with sodium bicarbonate and posthydration for 72 h with the same solution. On this protocol the mean values determined for the urinary protein content were all in the normal range (pretreatment, 0.03 g/m2/day; day 1, 0.05 g/m2/day; and day 2, 0.08 g/m2/day). These findings were significantly different from the previous results (P < 0.05).     

Radiological case of the month. Reflex sympathetic dystrophy

The authors report a case of pregnancy in a rudimentary horn diagnosed by laparotomy. The location could not be suspected by any clinical sign. This pregnancy stopped at 19 weeks of amenorrhoea. Any attempts of induction of labour failed. Laparotomy was necessary to assess the diagnosis and to allow the resection of the uterine horn. The authors present a review of literature.     

Prolonged tamoxifen exposure selects a breast cancer cell clone that is stable in vitro and in vivo

The effects of long-term tamoxifen exposure on cell growth and cell cycle kinetics were compared between oestrogen receptor (ER)-positive (MCF-7) and ER-negative (MDA-MB-231) cell lines. In the MCF-7 cell line, prolonged tamoxifen exposure (0.5 mumol/l for > 100 days) blocked cells in G0-G1 of the cell cycle, and slowed the doubling time of cells from 30 to 59 h. These effects corresponded to an increase in the cellular accumulation of tamoxifen over time [mean area under concentration curve (AUC) = 77.92 mumoles/10(6)/cells/day]. In contrast, in the MDA-MB-231 cell line, long-term tamoxifen exposure had no obvious effect on the doubling time, and reduced cellular tamoxifen accumulation (mean AUC = 50.50 mumoles/10(6)/cells/day) compared to the MCF-7 cells. Flow cytometric analysis of MDA-MB-231 cells demonstrated that a new tetraploid clone emerged following 56 days of tamoxifen exposure. Inoculation of the MDA-MB-231 tetraploid clone and MDA-MB-231 wildtype cells into the opposite flanks of athymic nude mice resulted in the rapid growth of tetraploid tumours. The tetraploid tumours maintained their ploidy following tamoxifen treatment for nine consecutive serial transplantations. Histological examination of the fifth transplant generation xenografts revealed that the tetraploid tumour had a 25-30 times greater mass, area of haemorrhage and necrosis, a slightly higher mitotic index and was more anaplastic than the control neoplasm. The control wildtype MDA-MB-231 tumours maintained a stable ploidy following tamoxifen treatment until the eighth and ninth transplantation, when a tetraploid population appeared, suggesting that tamoxifen treatment may select for this clone in vivo. These studies suggest that prolonged tamoxifen exposure may select for new, stable, fast growing cell clones in vitro as well as in vivo.     

Pain characteristics and their management in persons with AIDS

Discussion of pain problems in persons with AIDS has been limited in medical and nursing literature, yet pain is a major source of suffering and concern for patients. Common pain characteristics are described in 100 persons with CDC-defined AIDS, using the 1987 definition. The two most frequently cited types of pain for both drugs users and nondrug users with AIDS were abdominal pain and neuropathic pain. Drug users experienced pain due to esophagitis and headaches more frequently than nondrug users, while nondrug users experienced Kaposi's sarcoma-related pain more often. Treatment responses were individualized, with drug users requiring more frequent use of opiates. General treatment strategies are suggested with special emphasis on the unique needs of PWAs.