Search PubMed⌕ Search

Biomedical subjects

M Berry

Publications and source records attributed to M Berry.

At least 253 records · Page 14Linked to original sources
PubMed1988

Link-Vertex Analysis of Purkinje cell dendritic trees from the murine cerebellum.

A method of analysis of dendritic trees is described, called Link-Vertex Analysis, which defines the branching patterns (topology) by means of a discontinuous function, the terminal/link (T/L) vertex ratio, computed at all successive vertex orders within a network, and represented as a graphical plot for a given tree. The T/L vertex ratio is defined as the number (n) of terminal (pendant) vertices (Vp) divided by the total number (n) of all link vertices (both dichotomous, Vd, and trichotomous, Vt) multiplied by the number of segments arising from each vertex--i.e., nVp/(2nVd + 3nVt) per vertex order. Hypotheses of growth are simulated by computer modelling and the distributions of computer generated T/L vertex ratios per order compared with those of actual dendritic trees. The differential distribution of T/L vertex ratios per order in trees grown by either random terminal or random segmental branching discriminates between these two forms of growth. Significant advances of this method include the detection of regional variations in growth and remodelling in a tree and the incorporation of Vt with little perturbation of the Vd data. The analytical powers of this method have been tested using the dendritic fields of 20-day-old mouse cerebellar Purkinje cells defining possible temporal sequences and relative contributions of random and non-random terminal growth, and also the frequency of branching over a growth front relative to that of the rest of the tree.

Animals↗
PubMed1988

Regeneration of adult rat retinal ganglion cell processes in monolayer culture: comparisons between cultures of adult and neonatal neurons.

The aim of the present study was to develop a model culture system for the study of factors controlling regeneration of axons from injured adult mammalian central nervous system. We show, for the first that retinal ganglion cells (RGC) dissociated from adult rat retina, regrow processes in vitro over long distances under over appropriate conditions in monolayer culture. Most importantly, adult RGC depend completely upon the presence of a preformed layer of neonatal cortical astrocytes, whereas RGC from neonatal retinae are supported by indigenous retinal glia which spread and proliferate to form a monolayer of cells upon which RGC regrow processes. Adult retinal glia fail to spread on the culture surface and proliferate in the same way and we suggest that this is a major factor in limiting the survival of adult RGC on an acellular substrate such as polylysine. Laminin does not substitute for the presence of a glial monolayer. These findings indicate that at least one type of adult CNS neuron is capable of regenerating its processes in vitro in an environment which includes a cellular component of CNS tissue.

Age Factors↗
PubMed1988

The 5' flanking region of the human pS2 gene mediates its transcriptional activation by estrogen in MCF-7 cells.

The pS2 gene is transcriptionally induced by oestrogen in the human breast cancer cell line MCF-7. We demonstrate here that the 5' flanking sequences (-3000 to +10 bp) of the pS2 gene possess the properties of an oestrogen-inducible promoter. Interestingly, this oestrogen induction could not be demonstrated in transient transfection assays in MCF-7 cells, but only in stably transformed MCF-7 cells, which suggests that some factors responsible for oestrogen induction may be present in limiting amounts in these cells and absent in HeLa cells.

Base Sequence↗
PubMed1988

Structure and function of the pS2 gene and estrogen receptor in human breast cancer cells.

The role of estrogen in the growth of human breast cancers has been investigated at two levels. First, we have studied the pS2 gene, whose transcription is stimulated by estrogen in the human breast cancer cell line, MCF-7. The pS2 gene product is a small, secreted polypeptide currently of unknown function, but with structural features similar to some growth factors. The expression of the pS2 gene has so far been detected only in MCF-7 cells and some breast cancer biopsies. Preliminary studies indicate that pS2 is a potential marker for hormone-dependent breast cancer. Ongoing studies will continue to focus on the implicated role of pS2 in the estrogen-mediated growth of breast cancers and its possible use as a marker for estrogen-dependent tumors. Second, we have analyzed the structure and function of the human ER. The receptor stimulates pS2 gene transcription by interacting with an ERE in the 5'-flanking region of that gene. A mutational analysis of the receptor protein has localized a DNA-binding domain, which determines target gene specificity, and a hormone-binding domain. These domains appear to be the only two regions of the receptor which are absolutely required for the transcription-activating function of the ER in transfection assays with reporter plasmids. The N-terminal region of the protein (regions A and B), which is necessary for increasing the efficiency of gene expression using the pS2 ERE, but not a vitellogenin ERE, may also play a role in transcription activation. Further progress in the characterization of the ER functional domains will require studies on target genes in a more physiological chromatin environment, as well as detailed physical analyses of receptor structure.

Amino Acid Sequence↗
PubMed1988

Response of axons and glia at the site of anastomosis between the optic nerve and cellular or acellular sciatic nerve grafts.

Axonal and glial reactions at the site of optic nerve section and at the junctional zone between optic nerve and normal or acellular peripheral nerve grafts have been studied. Following optic nerve section, no axons grew into the distal optic nerve stump. Similarly, no axons invaded the acellular peripheral nerve grafts, although in both instances fibres did regenerate into the junctional zone and a few remained there at least until 30 days post lesion (dpl, the duration of the experiments). Axons regenerated into normal peripheral nerve grafts by 3-5 dpl and by 10 dpl large numbers had penetrated deeply into the grafts. The glial response to injury appeared similar in both groups of grafted animals. Astrocytes and oligodendrocytes grew out into the junctional zone over the 5-7 day period and invaded the margins of the cellular grafts by 10 dpl. They did not penetrate the acellular nerves or distal optic nerve stumps. We were unable to determine whether Schwann cells invaded the junctional zone from the normal peripheral nerve grafts. Schwann cells are both GFAP+ and Vim+, especially when reacting after injury, and Lam- when not associated with axons: it is therefore possible that Schwann cells from the cellular grafts contributed to the population of GFAP+, Vim+ cells in the junctional zone of the cellular grafts. Anti-laminin immunoreactivity persisted in the basal lamina tubes of both the normal and acellular peripheral nerve grafts. Thus, the failure of axon regeneration into acellular peripheral nerve grafts can be correlated with the absence of Schwann cells and does not appear to be related to the presence of laminin.

Anastomosis, Surgical↗
PubMed1988

Neither laminin nor prior optic nerve section are essential for the regeneration of adult mammalian retinal ganglion cell axons in vitro.

Retinal explants obtained from normal adult rats and from operated animals in which the optic nerve had been sectioned 10 days previously were cultured in either serum-containing or serum-free medium on poly-L-lysine and laminin substrata. Regenerating ganglion cell axons growing from these explants have been identified using monoclonal antibodies against Thy-1.1 cell surface glycoprotein and the 200-kDa subunit neurofilament protein. Irrespective of substratum or medium composition, axons regenerated from 28-49% of normal rat retinal explants. This percentage increased to 60-84% of explants from operated rats. There were no significant differences in percentages of explants from normal or operated rats showing neurite outgrowth when substrata of either poly-L-lysine or laminin were compared in serum-free medium. In serum-containing medium the results were less easily interpreted due to the presence of an outgrowth of non-neuronal (glia and mesenchymal) 'flat cells', which served as a preferred axonal substratum in many cases. Thus we show that adult rat retinal ganglion cell axons will regrow in vitro, and that a 'priming' optic nerve section will increase this response. In neither case is the response laminin-dependent.

Animals↗
PubMed1988

Duodenal fistula: complication of a pseudoaneurysm of the common hepatic artery.

An unusual case of an iatrogenic pseudoaneurysm arising from the common hepatic artery extending along the gastroduodenal artery and associated with an arterioduodenal fistula is reported. Angiography is the method for definitive diagnosis. In patients with obscure upper gastrointestinal bleeding, an arterioenteric fistula should be considered in the differential diagnosis, especially in those with previous vascular intervention.

Adult↗
PubMed1988

Emergency versus elective cholecystectomy in acute cholecystitis.

The present study was carried out at the Department of Surgery, All India Institute of Medical Sciences Hospital, New Delhi, between January 1982 and October 1984. Clinical diagnosis of acute cholecystitis was confirmed by ultrasound scanning or Tc99m labelled HIDA Scan. Group I (n=24) comprised patients who underwent emergency cholecystectomy while Group II (n=23) comprised patients who were managed conservatively, and had an elective cholecystectomy performed 6-12 weeks later. There was no mortality or wound infection in either group. The incidence of other complications was 8.3 per cent and 8.6 per cent in Groups I and II, respectively. Emergency cholecystectomy (Group I) reduced the total hospital stay of a patient by approximately 70 per cent and post cholecystectomy syndrome was seen in Group II patients only. We thus recommend emergency or early cholecystectomy during the acute stage of cholecystitis, as it is safe, effective and economical, provided it is done by an experienced surgeon.

Acute Disease↗
PubMed1988

Optic axons regenerate into sciatic nerve isografts only in the presence of Schwann cells.

Optic axons regenerate into normal but not acellular peripheral nerve (PN) grafts. The first axons penetrate the PN graft before 5 days and grow inside the basal lamina tubes amongst the Schwann cells. By 30 days, 4% of the surviving retinal ganglion cells (RGC) regenerate axons for at least 10 mm into the PN graft. Laminin rich basal lamina tubes persist in the acellular PN transplants but only a few axons penetrate the most proximal parts of the tubes by 5 days and none grow farther into the graft by 30 days. RGC counts demonstrate that 34% of the normal RGC population survive 30 days after anastomosing a normal PN to the transected optic nerve. After anastomosing acellular PN grafts, 25% of RGCs survive compared with 10% after optic nerve section. These findings demonstrate that laminin does not promote regeneration of axons and that Schwann cells play the primary role of offering trophic support and even a substrate for growth. RGC survival is also enhanced by PN grafts even when Schwann cells are absent. This latter result suggests that RGC survival is promoted by a trophic substance released from axons and/or Schwann cells in the PN grafts which survives the thawing/freezing procedure (used to kill the Schwann cells) and is active in the grafts in the immediate post operative period.

Animals↗
PubMed1988

Ascorbate peroxidase in bovine retinal pigment epithelium and choroid.

Peroxidase, catalyzing hydrogen peroxide reduction concurrent with ascorbate oxidation, was demonstrated in the extract of retinal pigment epithelium and choroid. The peroxidase in the choroid, RPE, and retina are 236.1, 25.1, and 0.5 units/mg protein respectively. Ammonium sulfate fractionation and high pressure liquid chromatography showed that the peroxidase in the RPE-choroid is associated with a group of heme proteins with absorption maxima at 410 nm, and optimal activity at pH 4.5. The high peroxidase activity in the RPE-choroid explains the observation of dehydroascorbate in these tissues and indicates a possible role of this enzyme in the removal of H2O2.

Ammonium Sulfate↗
PubMed1988

The endorphin response of women to sleep loss and exercise.

The purpose of this investigation was to examine the combined effect of sleep loss and exercise on plasma beta-endorphin levels. Seven healthy women completed a 1-h run at approximately 80% VO2 max on a motorized treadmill after a normal night's sleep and again after 36 h of sleep deprivation. Venous blood samples were obtained before and immediately after each run. Oxygen uptake, heart rate, blood pressure, and ratings of perceived exertion were obtained during each trial. Resting beta-endorphin levels were 4.5 +/- 0.2 pmol.L-1 for the control trial and 4.7 +/- 0.7 pmol.L-1 for the sleep deprived trials. Exercise after normal sleep resulted in an average endorphin level of 19.4 +/- 6.8 pmol.L-1. Sleep loss did not significantly alter the post-exercise beta-endorphin response, averaging 19.4 +/- 8.7 pmol.L-1. Both trials resulted in similar oxygen uptake (41.8 +/- 2.3 ml.kg-1.min-1), heart rate (163 +/- 4 beats.min-1), mean blood pressure (98 +/- 3 mm Hg), and rating of perceived exertion (12.0 +/- 0.2). These results suggest that 36 h of sleep deprivation does not impose sufficient stress to alter the resting endorphin response, nor does it affect the endorphin response to high-intensity exercise.

Adult↗