John Yeh

β-Amyloid fibrils induce tau phosphorylation and loss of microtubule binding

A central issue in the pathogenesis of Alzheimers disease (AD) is the relationship between amyloid deposition and neurofibrillary tangle formation. To determine whether amyloid fibril formation affects the phosphorylation state of tau, primary cultures of fetal rat hippocampal and human cortical neurons were treated with beta-amyloid (beta A) in a soluble, amorphous-aggregated, or fibrillar form. Fibrillar beta A, but not soluble or amorphous-aggregated beta A, markedly induces the phosphorylation of tau at Ser-202 and Ser-396/Ser-404, resulting in a shift in the tau M(r) in human cortical neurons. Hyperphosphorylated tau accumulates in the somatodendritic compartment of fibrillar beta A-treated neurons in a soluble form that is not associated with microtubules and is incapable of binding to microtubules in vitro. Dephosphorylation of beta A-induced tau restores its capacity to bind to microtubules. Thus, amyloid fibril formation alters the phosphorylation state of tau, resulting in the loss of microtubule binding capacity and somatodendritic accumulation, properties also exhibited by tau in the AD brain. Amyloid fibril formation may therefore be a cause of abnormal tau phosphorylation in AD.

Active management of the third stage of labour with and without controlled cord traction: a randomised, controlled, non-inferiority trial

BACKGROUND Active management of the third stage of labour reduces the risk of post-partum haemorrhage. We aimed to assess whether controlled cord traction can be omitted from active management of this stage without increasing the risk of severe haemorrhage. METHODS We did a multicentre, non-inferiority, randomised controlled trial in 16 hospitals and two primary health-care centres in Argentina, Egypt, India, Kenya, the Philippines, South Africa, Thailand, and Uganda. Women expecting to deliver singleton babies vaginally (ie, not planned caesarean section) were randomly assigned (in a 1:1 ratio) with a centrally generated allocation sequence, stratified by country, to placental delivery with gravity and maternal effort (simplified package) or controlled cord traction applied immediately after uterine contraction and cord clamping (full package). After randomisation, allocation could not be concealed from investigators, participants, or assessors. Oxytocin 10 IU was administered immediately after birth with cord clamping after 1-3 min. Uterine massage was done after placental delivery according to local policy. The primary (non-inferiority) outcome was blood loss of 1000 mL or more (severe haemorrhage). The non-inferiority margin for the risk ratio was 1·3. Analysis was by modified intention-to-treat, excluding women who had emergency caesarean sections. This trial is registered with the Australian and New Zealand Clinical Trials Registry, ACTRN 12608000434392. FINDINGS Between June 1, 2009, and Oct 30, 2010, 12,227 women were randomly assigned to the simplified package group and 12,163 to the full package group. After exclusion of women who had emergency caesarean sections, 11,861 were in the simplified package group and 11,820 were in the full package group. The primary outcome of blood loss of 1000 mL or more had a risk ratio of 1·09 (95% CI 0·91-1·31) and the upper 95% CI limit crossed the pre-stated non-inferiority margin. One case of uterine inversion occurred in the full package group. Other adverse events were haemorrhage-related. INTERPRETATION Although the hypothesis of non-inferiority was not met, omission of controlled cord traction has very little effect on the risk of severe haemorrhage. Scaling up of haemorrhage prevention programmes for non-hospital settings can safely focus on use of oxytocin. FUNDING United States Agency for International Development and UN Development Programme/UN Population Fund/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, Department of Reproductive Health and Research.

β-Amyloid Neurotoxicity in Human Cortical Culture Is Not Mediated by Excitotoxins

Abstract: β‐Amyloid is a metabolic product of the amyloid precursor protein, which accumulates abnormally in senile plaques in the brains of patients with Alzheimers disease. The neurotoxicity of 0‐amyloid has been observed in cell culture and in vivo, but the mechanism of this effect is unclear. In this report, we describe the direct neurotoxicity of β‐amyloid in high‐density primary cultures of human fetal cortex. In 36‐day‐old cortical cultures, β‐amyloid neurotoxicity was not inhibited by the broad‐spectrum excitatory amino acid receptor antagonist kynurenate or the NMDA receptor antagonist D‐2‐amino‐5‐phosphonovaleric acid under conditions that inhibited glutamate and NMDA neurotoxicity. In 8‐day‐old cortical cultures, neurons were resistant to glutamate and NMDA toxicity but were still susceptible to β‐amyloid neurotoxicity, which was unaffected by excitatory amino acid receptor antagonists. Treatment with β‐amyloid caused chronic neurodegenera‐tive changes, including neuronal clumping and dystrophic neurites, whereas glutamate treatment caused rapid neuronal swelling and neurite fragmentation. These results suggest that β‐amyloid is directly neurotoxic to primary human cortical neurons by a mechanism that does not involve excitatory amino acid receptors.

Nicotine and cotinine inhibit rat testis androgen biosynthesis in vitro

The effects of nicotine and cotinine, the major metabolite of nicotine, on testosterone production in rat testis were investigated. Rat Leydig cells were isolated and incubated with nicotine and cotinine. Nicotine produced a dose dependent increase in progesterone levels and a dose-dependent decrease in androstenedione and testosterone concentrations. Cotinine produced a dose-dependent increase in progesterone and androstenedione and a dose-dependent decrease in testosterone levels. The effects of nicotine and cotinine on rat testis mitochondrial cholesterol side chain cleavage enzyme and microsomal 3 beta-hydroxysteroid dehydrogenase-isomerase, 17 alpha-hydroxylase, 17,20-lyase and 17-ketosteroid reductase were examined. Nicotine competitively inhibited 17 alpha-hydroxylase (apparent Ki = 30 microM) and 17,20-lyase (apparent Ki = 18 microM). Cotinine competitively inhibited 17-ketosteroid reductase (apparent Ki = 46 microM). The addition of nicotine to preparations of rat testis microsomes yielded a Type II cytochrome P-450 binding spectrum. We conclude that nicotine and cotinine competitively inhibit multiple steps in testosterone biosynthesis.

Transforming Growth Factor-β1, -β2, -β3and Their Type I and II Receptors in HumanTerm Placenta

Expression of transforming growth factor (TGF)-β3 as well as cellular localization of TGF-β receptors has not been demonstrated in placenta. TGF-β receptor type I (RI) and type II (RII) are required to transmit TGF-β signals, therefore the determination of cells expressing both receptors in concert is necessary to identify target cells for TGF-β. We investigated presence and localization of TGF-βs and their receptors (RI, RII) in human term placenta using reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. RT-PCR showed that messenger RNA for TGF-β1, -β2, -β3, and RI and RII is present in human term placenta. We found intense staining for all TGF-β isoform and receptor proteins in the syncytiotrophoblastic layer, chorionic plate, and in cells of the extravillous trophoblasts using immunohistochemistry. The simultaneous expression of ligands and their receptors support the hypothesis that TGF-β may play an important role in regulating growth, differentiation, and function of the human placenta.

The role of apoptosis in gynaecological malignancies.

Apoptosis is a process of single-cell deletion requiring active participation of the cell in its own demise. First described in 1972, it is now known to play a major role in embryogenesis, tissue homeostasis and neoplasia. Apoptosis can be initiated when DNA damage occurs causing the cell to pause in its reproductive cycle. If the DNA damage is beyond repair, the cell proceeds to apoptotic cell death. When the genetic mechanism(s) involved in the pathway of apoptosis is altered, the cell does not die. Further mutations occur by proliferation and such multiple mutational events can lead to a malignant phenotype and cancer growth. The tumour suppressor gene p53 causes a DNA-damaged cell to rest and attempt repair. If damage is irreparable, p53 levels will continue to increase, initiating apoptosis. Mutation of p53, found in approximately 50% of cancers, can stop the apoptotic process. Increased bcl-2 expression, an apoptosis inhibitor, also plays a role in cellular transformation and cancer growth. Its altered expression occurs in the presence of oncogene expression. This paper reviews the role of apoptosis in malignant transformation, cancer growth, and response to therapy for gynaecological cancers. For cervical cancer and its precursors, data on apoptotic index, bcl-2 and Bax expression are presented and discussed in relationship to human papillomavirus expression. In ovarian epithelial malignancies, the role that apoptosis plays in chemotherapeutic responses is reviewed. The data for endometrial cancer are currently limited to apoptotic index.

Transforming growth factor type alpha in normal human adult saliva

Abstract For the first time, transforming growth factor alpha (TGF-α) has been detected in the saliva of healthy adults. In saliva, the concentrations of TGF-α and epidermal growth factor (EGF) were determined by radioimmunoassay (RIA) to be 1–6 μg/1 saliva and 0.5–2 μg/1 saliva, respectively. The salivary TGF-α was partially purified about 1200-fold by an ethanol extraction, Bio-Gel P-30 molecular sieve chromatography and reverse-phase high-performance liquid chromatography (HPLC). At least three forms of TGF-α, with molecular weights of 6 kDa or less, were detected with molecular sieve gel filtration chromatography. A major chromatography peak, which constituted 20–30% of the extract, was a 5.6 kDa human TGF-α (hTGF-α) molecule by using RIA, radioreceptor assay (RRA), and mitogenic activity assay techniques. Reverse-phase HPLC purification further confirmed the identity of TGF-α. Our findings suggest, in contrast to what was earlier assumed, that TGF-α is present in normal adult saliva and we hypothesize that it may play a significant role in mediating proliferation and other functions of epithelial cells in the alimentary system.

Twenty-four-hour urinary-free cortisol in premenopausal cigarette smokers and nonsmokers

Cigarette smoking has been reported to produce acute increases in plasma ACTH and cortisol, but the effect of chronic smoking on integrated adrenal steroid production has not been studied. The effects of chronic smoking on 24-hour urinary-free cortisol, 11-deoxycortisol, DHEAS, and 17-keto-steroids were studied in 10 premenopausal smokers, and their results were compared with 15 premenopausal nonsmokers. The 24-hour excretion of urinary-free cortisol (85.0 +/- 40.8 nmol/d in smokers versus 81.7 +/- 49.7 nmol/d in nonsmokers), 11-deoxycortisol (259 +/- 170 nmol/d in smokers versus 222 +/- 147 nmol/d in nonsmokers), DHEAS (3,140 +/- 2,909 nmol/d in smokers versus 2,890 +/- 1,960 nmol/d in nonsmokers), and 17-ketosteroids (17.4 +/- 8.3 mumol/d in smokers versus 23.4 +/- 19.9 mumol/d in nonsmokers) were similar in smokers and nonsmokers (all P values not significant). We conclude that chronic smoking does not result in abnormal levels of 24-hour urinary-free cortisol.

Müllerianosis: four developmental (embryonic) mullerian diseases.

The theory of müllerianosis predicts that embryonic müllerian tissue, misplaced during organogenesis, results in the formation of 4 benign müllerian diseases—developmental adenomyosis, endometriosis, endosalpingiosis, and endocervicosis—(developmental müllerian diseases) that will be identified in human female fetuses, infants, children, adolescents, and adults. Direct evidence is presented to support the existence of developmental adenomyosis, developmental endometriosis, and developmental endocervicosis in human female fetuses along with strong circumstantial evidence supporting the existence of all 4 developmental müllerian diseases in human female infants, children, adolescents, and adults. This evidence throws light upon the pathogenesis of rare müllerian lesions whose pathogenesis remains inexplicable by classical and modern theories. Furthermore, this research has scientific and clinical relevance: scientific relevance because it opens up a new field of comparative research—the 4 developmental müllerian diseases complement the 4 acquired müllerian diseases; clinical relevance because it identifies rare müllerian diseases curable by complete surgical excision.

Synergistic effects of endothelin-1 (ET-1) and transforming growth factor alpha (TGF-α) or epidermal growth factor (EGF) on DNA replication and G1 to S phase transition

The cooperative cell kinetic actions of ET-1 with TGF-α or EGF in normal rat kidney fibroblasts (NRK-49F) and KNRK cells (Kirsten MSV transformed) were analyzed by [3H]-thymidine incorporation assay and flow cytometry. A marked synergistic effect of TGF-α and ET-1 (or EGF and ET-1) on DNA synthesis and G1 to S transition was observed in NRK cells; 15–20% S for TGF-α and 12% S for ET-1 alone but 45–50% S in combination. There was no detectable effect on cell cycle kinetics by TGF-α (1 ng/ml) or EGF (1 ng/ml) plus ET-1 (1 ng/ml) in KNRK cells treated for 22 hours. Insulin, insulin-like growth factor I (IGF-I), fibroblast growth factor (FGF), platelet derived growth factor (PDGF), and transforming growth factor β (TGF-β) were also tested and found to have no significant synergistic effects on ET-1 actions. Our findings suggest that the combination of TGF-α (EGF) and ET-1 is an important part of an intricate network which coordinates progression of G1 to S phase in normal cells.