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Biomedical subjects

Chris Wood

Publications and source records attributed to Chris Wood.

10 recordsLinked to original sources
PubMed2006

Intraocular lens pupillary capture after neodymium:YAG laser treatment of interlenticular opacification of posterior chamber piggyback intraocular lenses.

A hyperopic 73-year-old woman had bilateral phacoemulsification with primary implantation of piggyback AcrySof intraocular lenses (IOLs) (Alcon) in the capsular bag. Interlenticular opacification (ILO) developed after 6 months in the left eye and after 2 years in the right eye. Treatment of the ILO in the left eye with a neodymium:YAG (Nd:YAG) laser resulted in pupillary capture of the optic of the anterior IOL. This case shows that despite using low energy levels, pupillary capture of the anterior IOL can occur after Nd:YAG laser treatment for ILO in piggyback IOLs.

Acrylic Resins↗
PubMed2006

Sperm channel diversity and functional multiplicity.

Ion channels are extraordinarily efficient machines that move ions in diversely controlled manners, allowing cells to rapidly exchange information with the outside world and with other cells. Communication is the currency of fertilization, as it is of most fundamental cell signaling events. Ion channels are deeply involved in the dialogue between sperm, its surroundings, and the egg. How sperm swim, find the egg and fertilize it depend on ion permeability changes modulated by environmental cues and components of the egg outer layer. Different ion channels distinctly localized in these tiny, amazing cells perform specific decoding functions that shape the sophisticated behavior of sperm. It is not surprising that certain sperm ion channels are turning out to be unique. New strategies to characterize sperm ion transport have opened exciting possibilities to dissect sperm-egg signaling and unveil novel contraception targets.

Acrosome Reaction↗
PubMed2005

Calcium channels and Ca2+ fluctuations in sperm physiology.

Generating new life in animals by sexual reproduction depends on adequate communication between mature and competent male and female gametes. Ion channels are instrumental in the dialogue between sperm, its environment, and the egg. The ability of sperm to swim to the egg and fertilize it is modulated by ion permeability changes induced by environmental cues and components of the egg outer layer. Ca(2+) is probably the key messenger in this information exchange. It is therefore not surprising that different Ca(2+)-permeable channels are distinctly localized in these tiny specialized cells. New approaches to measure sperm currents, intracellular Ca(2+), membrane potential, and intracellular pH with fluorescent probes, patch-clamp recordings, sequence information, and heterologous expression are revealing how sperm channels participate in fertilization. Certain sperm ion channels are turning out to be unique, making them attractive targets for contraception and for the discovery of novel signaling complexes.

Animals↗
PubMed2005

Computer Aided Detection (CAD) for breast MRI.

Since 1999, there has been a 40 percent increase per year in the number of breast MR studies performed in the United States. In addition, over 1200 sites in the United States have purchased surface coils for use in breast MR. This number is expected to grow to over 2,000 coils by the end of 2007. It is well accepted that MR sensitivity for invasive breast cancers is near 100%, but as the use of breast MRI increases, radiologists interpreting breast MR are challenged to achieve high specificity while retaining high sensitivity. Reading the large number of acquired MR images in a reasonable amount of time also becomes more important as the number of studies increases. Breast MR acquisition and image interpretation techniques have been refined through clinical optimization. The number of images to interpret, however, has increased to several hundred per case. Computer Aided Detection (CAD) algorithms have allowed radiologists to regain efficiency while maintaining optimized acquisition techniques. The first CAD system for breast MR (CADstream by Confirma, Inc.) was launched in January 2003. The CAD installed base has since grown to over 150 systems in the US. The primary reason for this quick adoption of CAD for breast MR is that the CAD software enables readers to increase their efficiency while potentially improving their overall accuracy. The full benefits CAD for Breast MR are realized when the interpreting radiologist has a thorough understanding of the algorithms used, and the limitations of CAD.

Breast Neoplasms↗
PubMed2004

Differential protein synthesis and expression levels in normal and neoplastic human prostate cells and their regulation by type I and II interferons.

Protein expression and de novo synthesis in normal and prostate cancer cell lines derived from the same patient were compared by proteomic analysis, and the effects of INFalpha and INFgamma (INF=interferon) determined. The expressions of several INF-inducible proteins, including MxA, Nmi, PA28a and IFP53, were downregulated in the cancer cells. INFgamma induced a more than twofold increase or decrease in the synthesis rates of almost twice as many proteins in the cancer cell line. The positive regulator of INF-induced transcription ISGF3gamma was upregulated in the cancer cells and inversely regulated by INFalpha and INFgamma in the normal and cancer cells. Moreover, ISGF3gamma's induction by INFgamma in the cancer cells was more enhanced by simultaneous stimulation with EGF, than its induction in the normal cells. In all, 31 differentially regulated proteins were identified by mass spectrometry analysis, several of which are involved in chaperone-assisted protein folding in the endoplasmic reticulum (ER) or in regulated protein degradation. Our results suggest that the exclusion of proteins by the ER quality control system, crosstalk between the EGF- and INF-induced signalling pathways and the regulation of INF-inducible genes are all altered in the prostate cancer cells. The combination of upregulated activity in the growth-promoting PI3K/Akt pathway, suppression of Nmi and overexpression of hnRNP-K and c-myc proteins may explain why the prostate cancer cells were found to be more resistant to the growth inhibitory effects of INFgamma.

Carrier Proteins↗
PubMed2003

Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes.

In ascidians, as in mammals, sperm trigger repetitive Ca2+-waves that originate from cortical pacemakers situated in the vegetal hemisphere of the zygotes. In ascidians, a vegetal protrusion termed the contraction pole (CP) acts as the Ca2+-wave pacemaker, but the mechanism that underlies the generation of a Ca2+-wave pacemaker is not known. Here, we tested four hypotheses to determine which factors at the CP are involved in setting the pace of the ascidian Ca2+-wave pacemaker: (1) localized Ca2+ influx; (2) accumulation of phosphatidylinositol (4,5)bisphosphate [PtdIns(4,5)P2]; (3) accumulation of cortical endoplasmic reticulum (cER); and (4) enrichment of the sperm activating factor. We developed a method of dynamically monitoring the location of the CP during fertilization using a plekstrin homology (PH) domain from phospholipase Cdelta1 coupled to green fluorescent protein (GFP) that binds PtdIns(4,5)P2. We found that eggs in Ca2+-free sea water displayed Ca2+ waves that originated from the CP, showing that enhanced CP Ca2+ influx does not determine the origin of the pacemaker. Also, disruption of the PH::GFP-labelled CP once it had formed did not dislodge the Ca2+-wave pacemaker from that site. Next, when we prevented the accumulation of cER at the CP, all of the Ca2+ waves came from the site of sperm-egg fusion and the frequency of Ca2+ oscillations was unaltered. These data show that local Ca2+ influx, the accumulation of PtdIns(4,5)P2 and cER at the CP are not required for Ca2+-wave pacemaker function and instead suggest that a factor associated with the sperm determines the site of the Ca2+-wave pacemaker. Finally, when we injected ascidian sperm extract into the centre of unfertilized ascidian eggs that had been treated with microfilament- and microtubule-disrupting drugs, all the Ca2+ waves still originated from near the plasma membrane, showing that the sperm factor does not require an intact cortex if it is enriched near the plasma membrane (PM). We suggest that the Ca2+-releasing sperm factor might be tethered near or on the PM and that following the cortical contraction, it is translocated to the vegetal CP, thus making that site act as a Ca2+-wave pacemaker.

Actin Cytoskeleton↗
PubMedDate not supplied

The prehospital administration of intravenous methylprednisolone lowers hospital admission rates for moderate to severe asthma.

OBJECTIVE: To compare hospital admission rates for patients with moderate to severe asthma who receive intravenous methylprednisolone given in the prehospital setting versus in the emergency department. METHODS: A retrospective chart review was used to identify emergency medical services (EMS) transports of patients with moderate to severe asthma when 125 mg methylprednisolone was given intravenously in the prehospital setting under existing regional protocols. Data were collected on EMS runs in an urban/suburban system from May 1, 2000, through April 30, 2001. Only patients 18 to 50 years old with a history of asthma were included in the study. Patients were excluded if they left against medical advice, were long-term smokers, used home oxygen, or had a history of chronic obstructive pulmonary disease. A parallel search was performed from February 1, 1999, to April 30, 2000, to identify moderate-severe asthmatics who were transported by EMS and later given intravenous methylprednisolone in the emergency department. During this period, methylprednisolone was not available for use in this EMS system. RESULTS: A total of 31 moderate to severe asthmatics were identified as receiving prehospital methylprednisolone. A total of 33 asthmatics were identified who were transported by EMS and later received intravenous methylprednisolone in the emergency department. Average patient age in the prehospital methylprednisolone group was 34+/-10 years (mean+/-standard deviation; 95% confidence interval [CI]=31-37). Average age in the hospital group was 34+/-10 years (95% CI=31-37). Average time to administration of methylprednisolone in the prehospital setting was 15+/-7 minutes (95% CI=7-22). The average time elapsed in the emergency department before methylprednisolone was 40+/-22 minutes (95% CI=23-57). Only 12.9% (4) of the patients receiving prehospital solumedrol were admitted versus 33.3% (11) of those receiving the medication in the emergency department (p=0.025). Patients were 3.375 times more likely to be admitted if they received methylprednisolone in the emergency department versus in the prehospital setting. CONCLUSION: Patients with moderate to severe asthma who receive intravenous methylprednisolone in the prehospital setting have significantly fewer hospital admissions.

Adult↗