Hepatocyte growth factor/scatter factor has distinct classes of binding site in heparan sulfate from mammary cells

Hepatocyte growth factor/scatter factor (HGF/SF) is a heparan sulfate (HS)-binding growth factor and morphogen for mammary epithelial cells that is produced by mammary stromal fibroblasts. HS chains, purified as peptidoglycans from a panel of cell lines representative of the ductal epithelial cell (Huma 123), the myoepithelial cell (Huma 109), the stromal fibroblast (Rama 27), and malignant mammary epithelial cells (MCF-7 and ZR-75), were used in a biosensor-based assay to identify the classes of HGF/SF-binding sites in the polysaccharide chains. At least three distinct binding sites were identified. One site exhibits fast association and fast dissociation kinetics [kass (1.4-7.7) x 10(6) M-1 s-1; kdiss 0. 0032-0.0096 s-1] and is present on the HS from benign Huma 123 epithelial cells, Huma 109 myoepithelial-like cells, and ZR-75 malignant cells. The second binding site, found on HS from the malignant MCF-7 cells, has slower HGF/SF-binding kinetics (kass 0.20 x 10(6) M-1 s-1; kdiss 0.00055 s-1). The third binding site possesses fast association and slow dissociation kinetics (kass 1.1 x 10(6) M-1 s-1; kdiss 0.00020 s-1) and was found on the HS isolated from the culture medium of the Huma 123 benign epithelial cells. The first and second binding sites have a similar Kd, 1-3 nM, while the third binding site has a considerably higher affinity for HGF/SF (Kd 200 pM). The three binding sites seem to be mutually exclusive, since each sample of HS possessed just one of the sites.     

Emergency and prolonged use of intravenous etomidate to control hypercortisolemia in a patient with Cushing's syndrome and peritonitis

We report the emergency and prolonged use of etomidate to control circulating cortisol levels in a patient with Cushing's syndrome secondary to ectopic ACTH production from a pancreatic islet cell tumor. Duodenal perforation and peritonitis complicated an episode of salmonella septicemia, precluding the use of conventional oral medical adrenolytic therapy. Endogenous cortisol secretion was abolished by parenteral etomidate, allowing serum cortisol levels to be controlled with an iv infusion of hydrocortisone over an 8-week period in intensive care before definitive pancreatic surgery.     

Experiences with functional magnetic resonance imaging at 1 tesla

Functional magnetic resonance imaging (fMRI) has been performed on a standard 1 T system using a pulse sequence developed to utilize blood oxygen level dependent (BOLD) contrast and an off-line analysis routine using correlation techniques. The sequence and the data analysis routine have been validated by reproducing the conventional hand movement paradigm studies reported by numerous other workers. Our work has then been extended to investigate cerebral foci for a tonic pain stimulus and the cortical representation of oesophageal stimulation. Both these studies relate to paradigms where the expected BOLD signal is significantly less than that encountered for motor or visual cortex paradigms. The results show good agreement with other modalities (positron emission tomography, magnetoencephalography and cortical evoked potentials). Performing fMRI at 1 T is slightly controversial. However, our successful study of demanding paradigms, using a standard clinical 1 T imaging system, has important implications for many other users operating at this field strength.     

Densities of mink frogs, Rana septentrionalis, in New Brunswick forest ponds sprayed with the insecticide fenitrothion

Many beta-adrenoceptor antagonists are weak partial agonists, possessing significant intrinsic sympathomimetic activity (ISA). Under certain conditions, ISA may be deleterious through stimulation of beta 1- and/or beta 2-adrenoceptors in the heart. Drugs with ISA are particularly problematic in the treatment of congestive heart failure since agents that activate cardiac beta-adrenoceptors, such as xamoterol, have been associated with increases in the incidence of arrhythmia and mortality. Carvedilol was recently approved for the treatment of congestive heart failure, and bucindolol is currently in large clinical trials for this indication. In the present study, the ISA of bucindolol and carvedilol was evaluated in a standard model used to investigate ISA, the pithed rat. Both compounds produced dose-dependent inhibition of the positive-chronotropic effects of the non-selective beta-adrenoceptor agonist, isoproterenol, confirming that these drugs are beta-adrenoceptor antagonists. However, cumulative administration of bucindolol (10-1,000 micrograms/kg i.v.) in the pithed rat produced a significant dose-related increase in heart rate. The maximal increase in heart rate produced by bucindolol was 44% of that obtained with isoproterenol (90 +/- 6vs. 205 +/- 11 bpm, respectively). In marked contrast, cumulative administration of carvedilol (10-1,000 micrograms/kg i.v.) had no significant effect on resting heart rate in the pithed rat. The maximal increase in heart rate elicited by bucindolol (1,000 micrograms/kg i.v.) was inhibited by treatment with the competitive beta-adrenoceptor antagonist, propranolol (99 +/- 8.7 vs. 26 +/- 2.6 bpm), confirming that the ISA observed with bucindolol was mediated through stimulation of myocardial beta-adrenoceptors. Carvedilol, which had no ISA, antagonized the ISA of bucindolol, and was as effective as propranolol in blocking the ISA of bucindolol (99 +/- 8.7 vs. 27 +/- 2.3 bpm). In summary, bucindolol and carvedilol are both potent beta-adrenoceptor antagonists in the pithed rat: however, only bucindolol possesses beta-adrenoceptor-mediated ISA.     

Characterization of the human cytomegalovirus UL97 gene product as a virion-associated protein kinase

The cellular localization and virion association of the human cytomegalovirus (HCMV) UL97 protein were studied. UL97 protein demonstrated early nuclear localization followed by late perinuclear accumulation. It was found to be a structural virion constituent detected in all three enveloped forms of extracellular viral particles and shown to be phosphorylated by the virion-associated protein kinase. UL97 protein immunoprecipitated from virions and from infected cells demonstrated protein kinase activity manifested by autophosphorylation. This activity was reduced in the presence of a ganciclovir-resistance mutation at residue 460, implicated in nucleotide binding. A mutant virus, from which the proposed UL97 kinase catalytic domain had been deleted, could not be propagated in the absence of a helper wild-type virus. The characterization of UL97 protein as a virion-associated protein kinase which appears essential for viral replication, provides further insight into HCMV replication and could identify a potential novel target for antiviral therapy.     

Intraosseous malignant peripheral nerve sheath tumor in a patient with neurofibromatosis

Malignant peripheral nerve sheath tumors (MPNSTs) are uncommon sarcomas that almost always arise in soft tissue. They can develop in pre-existing neurofibromas or schwannomas, de novo from peripheral nerves, or following radiation therapy. Primary intraosseous MPNST is rare and has been reported most frequently in the mandible. Of the reported cases involving the long bones, none has been associated with neurofibromatosis type 1 (NF-1). We report a case of MPNST arising in the femur in a patient with NF-1.     

Risk factors for above-knee amputations in diabetes mellitus

BACKGROUND: Above-knee amputation (AKA) is a common complication in diabetics, mostly after one or more lower level amputations (LEAs) have been done. The aim of this study was to identify risk factors for AKAs among diabetics. METHODS: We abstracted 1,800 medical records of hospitalizations for LEA. Kaplan's comorbidity classification was used to rank disease severity. We used both univariate and multivariate models to identify risk factors for AKA. RESULTS: Of the 1,043 diabetic amputees in this study, 22% had AKA. Variables associated with AKA were locomotor impairment, severe anemia, history of lower extremity bypass surgery, body mass index (BMI) < 20 kg/m2, female sex, cerebrovascular disease, cardiovascular disease, and SGOT > 40 U/L. CONCLUSIONS: Most of these risk factors represent end-stage processes and do not have good treatment alternatives. Perhaps one of the practical applications of these data is not to describe risk of proximal amputations but instead to look more closely at candidates who should be considered for distal procedures.     

Recent advances in infertility treatment

Infertility is defined as the inability to conceive after one year of regular coitus without contraception. Approximately 10% to 20% of childbearing-age couples are infertile in the United States. The demand for infertility investigations has increased dramatically in recent decades. The number of women using infertility services rose from 600,000 in 1968 to 1.35 million in 1988, an increase due, in part, to improved technology and increased publicity that began in the early 1980s. By 1995, the numbers were about 2.7 million. Recent advances in assisted reproductive technologies (ART) have provided greater possibilities for successful infertility treatment. Examples of new technologies include intracytoplasmic sperm injection, oocyte donation, and embryo cryopreservation.