Biomedical subjects

R R Hammond

Publications and source records attributed to R R Hammond.

22 records · Page 2Linked to original sources

PubMed1988

Haemodynamic effects of induction of epidural analgesia in labour.

The effect of induction of epidural analgesia with 0.5 per cent bupivacaine on maternal haemodynamics was investigated in 21 patients with uncomplicated full-term pregnancies in early labour. Stroke volume, heart rate, and cardiac output (SV, HR, and CO) were measured by transcutaneous aortovelography (TAV). Systolic, diastolic, and mean arterial blood pressures (SBP, DNP, and MAP) were measured by indirect automatic oscillometry. Measurements were made with the patient in the left lateral decubitus position before and after an intravenous bolus of 500 ml of lactated Ringer's solution preceding induction of epidural analgesia, and again 30 and 45 minutes after induction. The 500 ml bolus of lactated Ringer's solution did not prevent fall of CO and BP measured 30 minutes after induction, when there were statistically significant decreases in CO and cardiac index (-10.2 and -10.6 per cent, p less than 0.05), and in SBP, DBP, and MAP (-9.7, -12.5, and -11.9 per cent, p less than 0.005, p less than 0.005 and p less than 0.01 respectively). At 45 minutes after induction, CO and cardiac index had returned to baseline values. Although the decreases in SDP and DBP persisted, the change in MAP was not statistically significant.

Adult↗

PubMedDate not supplied

Neuron-enriched second trimester human cultures: growth factor response and in vivo graft survival.

Grafts of first trimester fetal tissue show limited survival and integration in the adult CNS. Alternative grafting strategies have been sought for treatment of neurodegenerative disease. We have developed cultures of human second trimester fetal tissues to study neuronal differentiation. Grafted into the SCID mouse striatum, aggregates of these cultures formed neuron-rich xenografts for at least 8 months. We examined the influence of various neurotrophic factors, including basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), transforming growth factor-beta 1 (TGF-beta1), and hepatocyte growth factor (HGF), on the growth and differentiation of neuronal and glial cell populations. BDNF promoted the survival and differentiation of second trimester neurons whereas bFGF exhibited a strong proliferative effect on precursors and the astroglial population. Our data suggest that second trimester human fetal cultures contain neuroprogenitor cells that can be directed to the neuronal lineage. This process may be amplified by treatment with BDNF, which we hypothesize could improve the long-term in vivo survival of neuron-enriched grafts.

Animals↗

PubMedDate not supplied

MAP2 and nestin co-expression in dysembryoplastic neuroepithelial tumors.

BACKGROUND: The ontogeny and maturity of neurons and oligodendroglia-like cells (OLC) found in dysembryoplastic neuroepithelial tumors (DNT) remains controversial. A developmental origin has been proposed based on the close association to cortical dysplasia and the benign microscopic and clinical course. Our goal was to characterize the expression of nestin, a neuroepithelial precursor/stem cell antigen in DNT, along with other pathological and clinical features of this entity. METHODS: The clinical and operative features of 13 surgical specimens meeting the histological criteria for DNT were reviewed. Nestin, microtubule-associated protein 2 (MAP2), neurofilament (NF) and glial fibrillary acidic protein (GFAP) were examined by immunohistochemistry and confocal scanning laser microscopy. RESULTS: Select neuronal cells in all cases demonstrated strong MAP2 immunoreactivity. Nestin-positive cells of neuronal morphology were found in 6 cases. OLC demonstrated frequent selective staining for MAP2, GFAP and nestin. Confocal microscopy demonstrated numerous examples of cells co-expressing nestin and MAP2. CONCLUSIONS: Our study suggests that OLCs represent a united population of immature neuronal (nestin + MAP2) and glial (GFAP) phenotypes. Larger, morphologically recognizable neurons also showed occasional co-expression of nestin and MAP2, suggesting a degree of dysmaturity in common with their OLC counterparts. The apparent mixed lineage of OLCs lends support to theories suggesting that DNTs arise from pluripotent neuroepithelial cells.

Adolescent↗

PubMedDate not supplied

Xanthoma disseminatum with massive intracranial involvement.

We present the case of a man who died 11 years after the onset of xanthoma disseminatum. His course was marked by numerous, large recurrent intracranial dural-based xanthomatous tumors requiring repeated neurosurgical intervention. Late in his course there was progressive quadriparesis, ataxia, ophthalmoplegia and bulbar palsy as a result of intraparenchymal brainstem involvement. At autopsy, there was extensive meningeal and intraparenchymal CNS disease and widespread systemic infiltrates. The gross and microscopic pathology are presented with immunohistochemical, ultrastructural and biochemical details. The present case is discussed in the context of the current classification scheme and the recent literature, where it is exceptional for the extent of CNS disease. Xanthoma disseminatum is currently classified as a non-X histiocytopathy, the pathogenesis of which remains uncertain. CNS involvement carries a poor prognosis in this otherwise benign condition.

Adult↗