Insulin increases CSF Abeta42 levels in normal older adults.

BACKGROUND: Abnormal insulin metabolism may contribute to the clinical symptoms and pathophysiology of AD. In vitro studies show that insulin enhances the release of beta-amyloid protein (Abeta) or inhibits its degradation, either of which might increase amyloid burden. METHODS: On separate mornings, 16 healthy older adults (10 women, 6 men; mean age 68.7 years, SD 8.6 years) each underwent two infusions consisting of either saline (placebo) or insulin (1.0 mU x kg(-1) x min(-1)) plus dextrose to maintain euglycemia. After 120 minutes of infusion, blood, CSF, and cognitive measures were acquired. RESULTS: As expected, insulin infusion produced an increase in CSF insulin concentration. Insulin infusion also led to an increase in CSF Abeta42 levels, most notably in older subjects. As has been observed previously, insulin infusion facilitated declarative memory, but such facilitation was attenuated in the subjects with the greatest increase in CSF Abeta42 levels. CONCLUSIONS: These findings are consistent with recent in vitro studies of insulin effects on Abeta and support the notion that insulin may modulate Abeta42 levels acutely in humans.

Autoantibodies and human leucocyte antigen class II in first-degree family members of Mexican-American type 1 diabetic patients.

As part of a genetic study of type 1 diabetes in Mexican-Americans, 360 first-degree relatives of 108 type 1 diabetic probands were studied. Islet cell antibody (ICA), insulin autoantibody, glutamic acid decarboxylase (GAD(65)), and protein tyrosine phosphatase autoantibodies were measured and human leucocyte antigen (HLA) class II alleles DRB1 and DQB1 genotyping was performed. ICA was positive in 37% of the probands and 5.8% of the relatives. A subgroup of 26 probands (12 ICA+, 14 ICA-) was tested for GAD(65) and was found positive. 4/14 ICA+ first-degree relatives were GAD(65) positive. Four relatives, positive for two antibodies, subsequently developed type 1 diabetes. Life-Table analysis of first-degree relatives with autoantibodies indicated an 80% disease-free survival at 3.5 yr. HLA-DRB1 was found to be associated with the presence of ICA in both probands and relatives, whereas HLA-DPB1 was associated with autoantibody in relatives of type 1 diabetic probands. These results suggest that autoimmunity occurs in type 1 diabetes families of Mexican descent in similar frequencies to that of non-Hispanic, Caucasian families. The presence of autoantibodies appears to be regulated in part by HLA class II genes, even in the absence of overt diabetes.

Fine-needle aspiration biopsy diagnosis of gastrointestinal stromal tumors using morphology, immunocytochemistry, and mutational analysis of c-kit.

BACKGROUND: Differentiating gastrointestinal stromal tumors (GISTs) from other intramural mesenchymal tumors of the GI tract on fine-needle aspiration biopsies (FNABs) is difficult. Recent studies have shown that GISTs are immunophenotypically and genetically distinct. GISTs exhibit consistent immunohistochemical expression of CD-117 (KIT) and often express activating mutations of this protooncogene. The aim of the current study was to employ immunocytochemistry and mutational analysis of the c-kit gene to aid in the diagnosis of GISTs on FNAB. METHODS: Five endoscopic ultrasound-guided FNABs of gastrointestinal spindle cell neoplasms performed at the Veterans Affairs Medical Center (VAMC) in Portland, Oregon, from 1998-1999 were reviewed. A panel of immunocytochemical stains was performed on each cellblock including CD-117 (KIT), smooth muscle actin (SMA), desmin, S-100, and CD34. Genomic DNA (gDNA) was extracted, and amplification of exons 9, 11, 13 and 17 of c-kit was performed by polymerase chain reaction (PCR) on CD-117 (KIT) and CD34 positive cases. Direct sequencing of amplicons identified the mutations. RESULTS: Five patients were diagnosed with GISTs based on morphology and immunocytochemical positivity for CD-117 and CD34. PCR analysis of c-kit exon 11 revealed three cases with novel-sized PCR bands in addition to the expected wild-type-sized PCR product. Amplicons from these cases contained an in-frame deletion mutation. One of the two cases with wild-type-;sized exon 11 amplicons was found to be heterozygous for a point mutation producing an amino acid substitution (W557R). No mutations in exon 9, 11, 13, or 17 of c-kit were found in the remaining case. CONCLUSIONS: Ancillary techniques such as immunocytochemistry and c-kit gene mutational analysis may aid in the diagnosis of GISTs on FNABs.

Inhibition of c-kit receptor tyrosine kinase activity by STI 571, a selective tyrosine kinase inhibitor.

STI 571 (formerly known as CGP 57148B) is a known inhibitor of the c-abl, bcr-abl, and platelet-derived growth-factor receptor (PDGFR) tyrosine kinases. This compound is being evaluated in clinical trials for the treatment of chronic myelogenous leukemia. We sought to extend the activity profile of STI 571 by testing its ability to inhibit the tyrosine kinase activity of c-kit, a receptor structurally similar to PDGFR. We treated a c-kit expressing a human myeloid leukemia cell line, M-07e, with STI 571 before stimulation with Steel factor (SLF). STI 571 inhibited c-kit autophosphorylation, activation of mitogen-activated protein (MAP) kinase, and activation of Akt without altering total protein levels of c-kit, MAP kinase, or Akt. The concentration that produced 50% inhibition for these effects was approximately 100 nmol/L. STI 571 also significantly decreased SLF-dependent growth of M-07e cells in a dose-dependent manner and blocked the antiapoptotic activity of SLF. In contrast, the compound had no effect on MAP kinase activation or cellular proliferation in response to granulocyte-macrophage colony-stimulating factor. We also tested the activity of STI 571 in a human mast cell leukemia cell line (HMC-1), which has an activated mutant form of c-kit. STI 571 had a more potent inhibitory effect on the kinase activity of this mutant receptor than it did on ligand-dependent activation of the wild-type receptor. These findings show that STI 571 selectively inhibits c-kit tyrosine kinase activity and downstream activation of target proteins involved in cellular proliferation and survival. This compound may be useful in treating cancers associated with increased c-kit kinase activity.

Co-transduction of cDNAs for c-kit and steel factor into single CD34+ cord blood cells further enhances the growth of erythroid and multipotential progenitors.

Previous studies have demonstrated that the c-kit encoded tyrosine kinase receptor and its ligand, steel factor (SLF), are critical for normal blood cell development. We have reported that transduction of the c-kit gene into single hematopoietic progenitor cells (HPC), CD34(+++) cells, from cord blood (CB) enhances erythroid colony formation via a SLF-dependent mechanism. We therefore decided to evaluate the impact on cell proliferation of co-transducing c-kit and SLF cDNAs into these cells. CD34(+++) cells were sorted as a population or as 1 cell/well for cells expressing the highest levels of CD34 and different levels of c-kit. Cells were then prestimulated with granulocyte macrophage (GM)-colony stimulating factor (CSF), interleukin (IL)-3, IL-6, erythropoietin (Epo) in the presence and absence of various concentrations of SLF. Cells were then transduced with SLF and/or c-kit cDNAs, and then assayed for colony formation with the same cytokine combination. At a single cell level, co-transduction with c-kit and SLF genes significantly enhanced colony formation compared with individual gene transduction, especially by erythroid and multipotential progenitors that responded to stimulation by added cytokines. Little or no growth was seen with the c-kit- and/or SLF-transduced cells without addition of cytokines. The degree of enhancement effected by co-transduction inversely correlated with the degree of expression of c-kit protein before transduction. Optimal enhancing effects were noted in CD34(+++) kit(Lo/-) cells co-transduced with both c-kit and SLF cDNAs. Reverse transcriptase-polymerase chain (RT-PCR) analysis of SLF mRNA expression in CD34(+++) cells and enzyme-linked immunoadsorbent assay (ELISA) measurement of secreted SLF protein demonstrated that the transduced SLF cDNA was expressed and soluble SLF was released in medium cultured with SLF gene transduced MACS-separated CD34(+) cells in the presence, but not in the absence, of IL-3, GM-CSF, IL-6, and Epo. These results demonstrate the enhancement of the proliferation of growth factor responsive HPC that express transduced c-kit and SLF genes.

Atracurium infusion during paediatric craniofacial surgery. Closed loop control of neuromuscular block.

A simple feedback control system was used to administer atracurium to 10 infants aged between 5 and 36 months during craniofacial reconstruction. The purpose of the study was to establish whether the system, previously evaluated only in adults, would be effective in paediatric patients. The individuals studied underwent long procedures with substantial blood loss and the potential for thermal and electrolyte disturbances. The system maintained the level of neuromuscular block successfully between 88 and 100% in all patients and between 90 and 100% in nine patients. The mean duration of feedback control was 179 (range 111-440) minutes. The mean (SD) dose of atracurium required was 0.40 (0.12) mg/kg/hour. The mean (SD) recovery time to a train-of-four ratio of 0.75 was 24.8 (9.9) minutes.

Feedback control of neuromuscular blockade. A simple system for infusion of atracurium.

A simple system for closed-loop control of neuromuscular blockade is described. It comprises a Datex Relaxograph, a small relay and a syringe pump. The equipment is commercially available and requires no complex custom-built electronics. Atracurium was infused in a semicontinuous manner to 11 patients who underwent general anaesthesia for a variety of surgical procedures. Neuromuscular blockade oscillated within a narrow range around the preset level. The mean rate of infusion of atracurium was 0.5 mg/kg/hour (SD 0.13). The mean recovery time was 25.5 minutes (SD 7.95).

Nizatidine: a new histamine receptor blocker in the treatment of active duodenal ulcers.

Forty-three patients with newly diagnosed duodenal ulcers were treated with a new histamine blocker, nizatidine, and with placebo. The incidence of complete endoscopic healing was 38, 74, and 82% in the nizatidine treated patients compared with 25, 37, and 50% in the placebo treated group after 2, 4, and 8 wk of treatment, respectively. Nizatidine was clearly more effective than placebo after 4 wk of treatment. The size of unhealed ulcers decreased more than 50% in 62, 50, and 50% in the nizatidine treated groups versus 27, 25, and 40% in the placebo treated groups after 2, 4, and 8 wk of treatment, respectively. The difference between the two was not statistically significant for any given period. There was a significant correlation between day pain relief and ulcer healing in both treatment groups. Nizatidine significantly improved day pain relief only after 8 wk of treatment (p less than 0.01). No patient developed any side effects as a result of nizatidine treatment, except that the serum creatinine level rose from 1.05 to 1.1 mg/100 ml but still remained within the normal accepted range. This study demonstrated that nizatidine at 150 mg po bid could be effectively used in the treatment of duodenal ulcer disease.