Neurotrophin receptor p75 mediates the uptake of the amyloid beta (Aβ) peptide,guiding it to lysosomes for degradation in basal forebrain cholinergic neurons

A fascinating yet perhaps overlooked trait of the p75 neurotrophin receptor (p75^NTR) is its ability to bind ligands with no obvious neurotrophic function. Using cultured basal forebrain (BF) neurons, this study demonstrates selective internalization of amyloid β (Aβ) 1–42 in conjunction with p75^NTR (labelled with IgG192-Cy3) by cholinergic cells. Active under resting conditions, this process was enhanced by high K⁺ stimulation and was insensitive to inhibitors of regulated synaptic activity—tetrodotoxin or botulinum neurotoxins (BoNT type/A and/B). Blockade of sarco-endoplasmic reticulum (SERCA) Ca²⁺ ATPase with thapsigargin and CPA or chelation of Ca²⁺ with EGTA-AM strongly suppressed the endocytosis of p75^NTR, implicating the role of ER released Ca²⁺. The uptake of IgG192-Cy3 was also reduced by T-type Ca²⁺ channel blocker mibefradil but not Cd²⁺, an indiscriminate blocker of high voltage-activated Ca²⁺ currents. A strong co-localization of IgG192-Cy3 with late endosome (Rab7) or lysosome (Lamp1) qualifier proteins suggest these compartments as the primary destination for internalized IgG192 and Aβ. Selective uptake and labeling of BF cholinergic cells with IgG192-Cy3 injected into the prefrontal cortex was verified also in vivo. The significance of these findings in relation to Aβ clearance in the cerebral cortex and pathophysiology of Alzheimer’s disease is discussed.     

Induction of mitochondria-dependent apoptosis by Abrus agglutinin derived peptides in human cervical cancer cell.

In our previous study, Abrus agglutinin showed antitumor activity both native and heat-denatured condition in mouse model. The purpose of this study is to explore the presence of anticancer peptide in agglutinin, and to elucidate the mechanism of its activity in vitro. A tryptic digested Abrus agglutinin peptide fractions obtained from 10-kDa molecular weight cut off membrane permeate (10 kMPP), was found to have selective antiproliferative activity (1-10 microg/ml) on several tumor cell lines in vitro without having any cytotoxic effect on normal cell lines with dose of 100 microg/ml. Analysis of the growth inhibitory mechanism in HeLa cells revealed nuclear fragmentation and condensation with appearance of the sub-G 0/G1 peak indicative of apoptosis. Furthermore, the peptide fraction induced the apoptosis signal via generation of reactive oxygen species and decrease in the Bcl-2/Bax ratio thereby inducing mitochondrial permeability transition with consequent activation of caspase-3, finally leads to DNA fragmentation, and the hallmark of apoptosis. LC-MS/MS analysis reflected the molecular masses of peptides in 10 kMPP were in the range of 500 Da to 3000 Da. The significant antitumor activity of 10 kMPP deserves further laboratory and in vivo experimentation.     

Determination of Cause of Death Among Breast Cancer Cases in the Swedish Randomized Mammography Screening Trials: A comparison between official statistics and validation by an endpoint committee

Between 1976 and 1982, four randomized mammography screening trials started in five screening centres in Sweden, involving 282 777 women (156 911 invited and 125 866 controls) with the aim to study if invitation to screening reduced the breast cancer mortality. An overview of the trials was performed to reduce the confidence intervals for the relative risk estimates. All 1 296 deaths occurring in women with breast cancer detected after randomization were evaluated by an independent endpoint committee (EPC), consisting of four physicians who reviewed collected medical information that was blinded regarding mammography screening. If there was disagreement between the EPC members at the initial individual evaluation the final classification was made at concensus meetings. In only 6.9% (n = 89) of the cases was there disagreement as to whether breast cancer was or was not the underlying cause of death. It was also found that 'breast cancer as underlying cause of death' and 'breast cancer as underlying or contributory cause of death' according to Statistics Sweden resulted in relative risk estimates very similar to those based on the classification by the EPC. The study thus supports the use of official health statistics in the evaluation of randomized breast screening trials in Sweden.     

RB-reconstituted human retinoblastoma cells form RB-positive intraocular and intracerebral but not subcutaneous tumors in scid mice

WERI-Rb 27 human retinoblastoma cells were reconstituted with an intact RB gene by retrovirus-mediated gene transfer, in order to study the phenotypic effects of the protein in vitro and in vivo. Extensive morphological changes were observed, dominated by the formation of multinucleated giant cells. Six weeks after retroviral infection, the giant cells began to die and small cells emerged, resembling the parental non-reconstituted line. They expressed RB and continued to grow, although they showed an increased sensitivity to serum starvation. The original RB-negative cells grew progressively after subcutaneous inoculation into SCID mice, whereas the reconstituted cells failed to grow. RB-positive cells grew progressively in the corpus vitreum of the eye and in the brain, however. The RB-reconstituted cells grew more slowly and were less invasive than the parental cells and cells infected with a firefly luciferase (LUX) gene carrying retrovirus, used as controls. RB-reconstituted cells re-explanted from the intraocular and intracranial tumors continued to express full-length RB protein. RBeye2, an RB-positive cell line established from an eye tumor, was still unable to grow subcutaneously. The reduced tumorigenicity of the RB-reconstituted cells in the subcutaneous space may be due to the influence of locally acting growth-controlling signals or the absence of microenvironment-specific trophic factors. Alternatively, it may reflect the action of residual immune effectors in the SCID mice. If this is the case, these would have to be more effective at the subcutaneous site than in the eye or brain. © 1995 Wiley-Liss, Inc.     

Absent auditory brain stem response: Peripheral hearing loss or brain stem dysfunction?

Interpretation of auditory brain stem response (ABR) findings can be problematic in cases where waves III and V are absent. Such findings can be attributed to profound hearing loss, brain stem neuropathology, or both. Over a 3-year period, 48 patients with no known brain stem damage and on whom audiologic data were available were found to have no response by ABR or absent waves III and V. Severe to profound hearing loss was documented in 38 cases, audiometric data were equivocal in 3 cases, and 7 patients showed pure tone sensitivity ranging from normal hearing to moderate impairment. Thus 15% had better hearing sensitivity than might have been expected from their ABR findings. Each of these patients also exhibited abnormal acoustic reflex findings. We report the electrophysiological (ABR, MLR, acoustic reflex}, medical (history, neurological, EEG, CT scan) and behavioral (audiometric, speech and language, learning disabilities, psychological) data which characterize this group of patients.     

High urinary excretion of uric acid combined with high excretion of calcium links kidney stone disease to familial hypertension.

BACKGROUND: Past studies identified an association between kidney stone disease (KSD) and hypertension. We recently reported a high occurrence of hypertension in families of patients with hyperuricosuric KSD. As hypercalciura frequently coexists with hyperuricosuria and high urinary excretion of calcium is found in patients with hypertension, we hypothesized that hyperuricosuria that is accompanied by hypercalciuria better describes the familial association between KSD and hypertension. METHODS: Four hundred and eighty-six KSD patients, aged 18-50 years, attending a lithotripsy unit collected a 24-h urine sample for metabolic analysis and provided information on family history of hypertension. The familial occurrence of hypertension was compared among four groups of patients: those who had combined elevation of both urinary calcium and uric acid excretions ("combined" abnormality, n=56), those who had hyperuricosuria without concomitant hypercalciuria ("pure" hyperuricosuria, n=67), those who had hypercalciuria without concomitant hyperuricosuira ("pure" hypercalciuria, n=52), and a control KSD patient group ("other" abnormality, n=311). The prevalence of treated hypertension in patients from the four groups was 16%, 12%, 2%, 10%, respectively. RESULTS: Thirty-four per cent of the patients with the "combined" abnormality had a positive family history of hypertension, defined as two or more first-degree relatives with treated hypertension, that was significantly higher than in patients with either "pure" hyperuricosuira (15%, P<0.02), "pure" hypercalciuria (8%, P<0.001), or patients with "other" abnormality (10%, P<0.001). The adjusted OR for positive family history of hypertension in the "combined" abnormality group compared to the control KSD patient group was 5.6 (2.39-13.30). The prevalence of hypertension in siblings of patients with the "combined" abnormality (13%) was significantly higher than in siblings of patients with either "pure" hyperuricosuria (3%, P<0.001), "pure" hypercalciuria (1%, P<0.001), or siblings of control patients with "other" abnormality (4%, P<0.001). The adjusted OR for hypertension in siblings of a patient with "combined" abnormality compared to a control KSD patient was 3.4 (1.97-5.91). Patients in the "combined" abnormality group were also characterized by significantly elevated urinary sodium, phosphorus, citrate and potassium excretions. CONCLUSIONS: Our data suggest that there is a strong, independent association between familial occurrence of hypertension and the phenotype characterized by combined elevation of both urinary uric acid and calcium excretions. The association is not present in those with "pure" hyperuricosuria or "pure" hypercalciuria. Ascertainment of patients based on this phenotype may identify more homogeneous populations for genetic analysis of hypertension.