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Biomedical subjects

M L Evans

Publications and source records attributed to M L Evans.

At least 73 records · Page 4Linked to original sources
PubMed1995

Intrauterine repair of cleft lip-like defects in lambs with a novel microclip.

Potential for scarless wound healing in fetal surgeries has aroused interest in fetal repair of malformations such as cleft lip. However, current protocols for fetal surgery have entailed fetal externalization, imparting significant risks for mother and fetus. We have developed a unique silver microclip that rapidly approximates tissue, is nonpenetrating, and is well suited for endoscopic use. Using standardized intrauterine surgical techniques, we compared suture versus microclip in the repair of surgically created cleft-like defects in fetal lambs at 124 days' gestation (term, 145 days). Nine fetal lambs were analyzed with bilateral cleft lips; the right cleft was repaired by microclip, seven of the left clefts were repaired by suture, and the remaining two left clefts were not approximated (controls). Results demonstrated excellent wound healing and smooth lip continuity with minimal scar formation after repair by either microclip or suture. The most striking result, however, was in the comparison on intraoperative repair time; the total time for cleft lip repair by microclip averaged 2.5 minutes in contrast to 9.8 minutes for suture. These data suggest a distinct advantage of the microclip in reduction of operative time. Furthermore, its endoscopic application has the potential for making endoscopic fetal surgery a more viable option.

Animals↗
PubMed1995

A randomized cross-over study of the efficacy of codeine phosphate versus Ispaghulahusk in patients with gynaecological cancer experiencing diarrhoea during pelvic radiotherapy.

Diarrhoea is the commonest acute complication during radiotherapy treatment to the pelvis. Codeine phosphate and a low residue diet is the standard therapy for radiation-induced diarrhoea at The Royal Marsden NHS Trust. The hypothesis put forward was that Ispaghulahusk and codeine phosphate were equally effective in the treatment of diarrhoea during radiotherapy. Participants in the study were female patients who had experienced change of bowel habit whilst receiving radiotherapy for their gynaecological cancer. Quantitative data was collected from patient diaries and treatment flow-sheets. Ten patients were randomized into the trial, five to codeine phosphate, and five to Ispaghulahusk. Continuing the trial was questioned after 10 patients had been treated. All five patients in the codeine phosphate arm received adequate control, while the five patients allocated to the Ispaghulahusk arm were all crossed-over to codeine phosphate with resolution of their diarrhoea. The results show that Ispaghulahusk, whilst not totally ineffective at controlling diarrhoea, was significantly less effective than codeine phosphate. Our conclusion is that there is insufficient reason to change to a less effective and less palatable preparation for the control of radiation-induced diarrhoea.

Codeine↗
PubMed1995

Sleep during the week before labor: relationships to labor outcomes.

This correlational study was conducted to examine the relationship between maternal sleep during the nights prior to the onset of labor and labor outcomes of length, type of delivery, and maternal perceptions of labor. Subjects (N = 99) were drawn from childbirth education classes at a women's hospital in the southeastern United States. Subjects completed the Visual Analog Sleep Scale each morning, beginning two weeks prior to their due dates. Following delivery, subjects completed the Perception of Labor and Delivery Scale, and researchers gathered data about their labors. These women reported poor sleep effectiveness coupled with high sleep disturbance; however, there were no significant correlations between sleep quality and length of labor or maternal perceptions of labor for either the night, or the week, prior to the onset of labor. This finding leads us to question the view that disturbed prenatal sleep will interfere with the progress of labor and lead to more cesarean sections.

Adolescent↗
PubMed1995

Intrauterine repair of surgically created defects in mice (lip incision model) with a microclip: preamble to endoscopic intrauterine surgery.

We compared the difference between a nonpenetrating silver microclip and suture on wound healing, inflammatory response, and application time in the repair of surgically created standardized unilateral cleft lip type defects in fetal mice. Excellent lip continuity and dermal reconstitution were achieved by both methods of repair. Furthermore, collagen accumulation did not occur. Occasional mononuclear cells were seen around sutured repairs in contrast to microclipped repairs. The most significant difference, however, was in application time with the microclip requiring an average of 7 seconds (+/- 2) compared to 90 seconds (+/- 15) for suture. We conclude that the microclip offers distinct advantages for intrauterine cleft lip repair: (1) nonpenetrating tissue approximation; (2) less inflammatory response than suture; (3) technically more rapid and less difficult to apply than suture; and (4) can be utilized more readily than suture for endoscopic approaches limiting the risks of fetal surgery for both the mother and the fetus.

Animals↗
PubMed1994

Correlations between changes in electrical parameters and changes in cell elongation rates in gravistimulated roots.

The earliest changes in growth rate following the gravistimulation of roots occur in a special group of cells between the meristem and the elongating region of the root. This zone is called the postmitotic isodiametric growth (PIG) zone and consists of cells which have ceased dividing and are expanding isodiametrically. Upon gravistimulation cells along the upper side of the PIG zone begin elongating rapidly and this accounts for much of the early growth asymmetry. There is rapid (< 30 s) hyperpolarization of cells on the upper side of the PIG zone as well as rapid uptake of potassium from the stele. We propose that there is a relationship between the rate of hydrogen ion efflux and the extent of membrane hyperpolarization in the PIG zone and that such changes in potential are an early indication of impending changes in growth performance. Although the development of auxin asymmetry in the cap and its transmission to the elongating region is considered to be the controlling factor in root gravitropism, auxin asymmetry in the cap develops only after 30 min, about the same as the lag before initiation of curvature. Although this dilemma may be partly resolved by the location of the PIG zone close to the cap, alternative explanations such as gravi-detection by the PIG zone or very rapid (electrical?) signal transmission from the cap to the PIG zone need to be considered.

Biological Transport↗
PubMed1994

Improving technology: blood glucose testing.

Nurses frequently monitor blood glucose at the patient's bedside, allowing timely assessment and interventions. To meet the Joint Commission on Accreditation of Health Organization's requirements and guidelines from National Committee on Clinical Laboratory Standards and College of American Pathologists, quality control compliance must be maintained. After testing three blood glucose monitors, one institution selected a machine that eliminated handwritten documentation, ensured quality control testing, and improved ease of use.

Blood Glucose Self-Monitoring↗
PubMed1994

The t(14;18) in a patient with de novo acute lymphoblastic leukemia is associated with t(8;9).

Cytogenetic analysis of a bone marrow aspirate from a patient with acute lymphoblastic leukemia (ALL) revealed the presence of a complex karyotype containing the translocation, t(14;18)(q32;q21). Further investigations using fluorescence in situ hybridization (FISH) allowed the characterization of an additional translocation, t(8;9)(q24;p1?). The association of t(14;18)(q32;q21) and t(8;9)(q24;p13) has recently been described in two patients with de novo ALL (Nacheva et al. Blood 1993;82:231-240) and this report supports these findings.

Adult↗
PubMed1993

SB 201823-A, a neuronal Ca2+ antagonist is neuroprotective in two models of cerebral ischaemia.

We have characterised the Ca2+ channel blocking properties of a new non-peptide Ca2+ channel antagonist, SB 201823-A, in cultures of rat sensory neurones. The IC50 for SB 201823-A against total Ca2+ current in sensory neurones was 4.9 microM. SB 201823-A showed little selectivity for sub-types of neuronal Ca2+ channel but was selective for Ca2+ channels over Na+ and K+ channels. Efficacy against other types of cation channel such as agonist gated channels was not assessed. SB 201823-A was neuroprotective in vivo when administered post-ischaemia in one focal and one global model of neuronal ischaemia. In the rat photothrombotic focal lesion model, SB 201823-A administered i.p. 10 min post-ischaemia resulted in a dramatic reduction in lesion volume. In the gerbil bilateral carotid artery occlusion global model, SB 201823-A dosed i.p. 30 min post-occlusion resulted in both histological and functional improvements when compared to vehicle treated animals. These data suggest that such novel neuronal Ca2+ channel antagonists may have potential in ameliorating both the pathological and functional consequences of stroke in man.

Animals↗
PubMed1993

The role of the distal elongation zone in the response of maize roots to auxin and gravity.

We used a video digitizer system to (a) measure changes in the pattern of longitudinal surface extension in primary roots of maize (Zea mays L.) upon application and withdrawal of auxin and (b) compare these patterns during gravitropism in control roots and roots pretreated with auxin. Special attention was paid to the distal elongation zone (DEZ), arbitrarily defined as the region between the meristem and the point within the elongation zone at which the rate of elongation reaches 0.3 of the peak rate. For roots in aqueous solution, the basal limit of the DEZ is about 2.5 mm behind the tip of the root cap. Auxin suppressed elongation throughout the elongation zone, but, after 1 to 3 h, elongation resumed, primarily as a result of induction of rapid elongation in the DEZ. Withdrawal of auxin during the period of strong inhibition resulted in exceptionally rapid elongation attributable to the initiation of rapid elongation in the DEZ plus recovery in the main elongation zone. Gravistimulation of auxin-inhibited roots induced rapid elongation in the DEZ along the top of the root. This resulted in rapid gravitropism even though the elongation rate of the root was zero before gravistimulation. The results indicate that cells of the DEZ differ from cells in the bulk of the elongation zone with respect to auxin sensitivity and that DEZ cells play an important role in gravitropism.

Gravitation↗
PubMed1993

Novel use of positively charged nylon transfer membranes for trapping indoleacetic acid or other small anions during efflux from plant tissues.

Positively charged nylon blotting membranes were used as an anion binding medium to trap [14C]indoleactic acid (IAA) as it exited cells at the basal ends of Coleus blumei L. stem and Zea mays L. coleoptile segments. Autoradiography was used to visualize where the [14C] that moved out of the cut ends was localized on the nylon membrane. Diffusion of [14C]IAA from the initial point of contact with the nylon membrane was minimal. Comparison of the autoradiograms with anatomical tissue prints of the cut ends of the segments was used to determine what tissues participate in IAA movement. The results of these initial studies were consistent with other reports suggesting that [14C]IAA movement was primarily associated with vascular tissues in both C. blumei stems and corn coleoptiles, but the resolution was not sufficient to identify which vascular tissues were involved in IAA transport. With further refinements, this technique could also be used for studying the movement of other small charged molecules through plant tissues.

Anions↗
PubMed1993

Mitoxantrone and cytosine arabinoside as treatment for acute myelogenous leukemia (AML) at first recurrence.

A total of 107 patients with newly diagnosed acute myeloblastic leukemia (AML) were referred to the ICRF Department of Medical Oncology at St Bartholomew's Hospital between August 1986 and July 1989. Of those referred, 92 (87%) were treated with remission induction chemotherapy comprising: Adriamycin, cytosine arabinoside (ara-C) and 6-thioguanine if aged < 60 years (57 patients) or mitoxantrone (MTN) and ara-C if aged > 60 years (35 patients). Of those treated, 54 (58%) entered complete remission (CR). Recurrent AML developed in 38 out of these 54 patients (70%) of whom 25 aged 19-73 years (median 50 years) subsequently received MTN and ara-C as reinduction therapy. The 19 younger patients (under 60 years old) received MTN at 12 mg/m2, intravenously, daily for 5 days and ara-C at 100 mg/m2, intravenously, twice daily for 7 days. The six older patients received the same ara-C schedule but the dose of MTN was reduced to 10 mg/m2 for 5 days. Second CR was achieved in 16 out of 25 patients (64%) [12/19 (63%) and 4/6 (67%) for patients aged under or over 60 years, respectively]. Eight of the patients in whom second CR was achieved were aged under 50 years and were thus eligible for additional consolidation comprising myeloablative therapy with autologous bone marrow transplantation (ABMT). Four patients actually received the latter treatment: two remain in second CR at 21 and 46 months. Three of the remaining eight patients aged > 50 years in whom second CR was achieved remain in second CR 8 to 43 months later. Censored for myeloablative therapy + ABMT, the overall median duration of second CR was 5 months. Although remissions tended to be short, in younger patients the possibility of proceeding to myeloablative therapy with autologous bone marrow support makes the regimen worthwhile and, even in older patients, it was sometimes possible to achieve prolonged second remissions.

Adolescent↗
PubMed1993

Common pulmonary vein atresia: the role of extracorporeal membrane oxygenation.

Common pulmonary vein atresia is a rare form of cyanotic congenital heart disease in which the pulmonary veins join to form a blind confluence that does not communicate with the heart or the major systemic veins. Twenty-one cases have been reported since the lesion was first described in 1962; only two patients with this lesion have survived. Over a 4-year period, common pulmonary vein atresia was diagnosed in five newborns referred to the San Diego Regional Extracorporeal Membrane Oxygenation Program. All five improved dramatically as a result of venoarterial bypass. Congenital heart disease was diagnosed at autopsy in the initial case and by cardiac ultrasound and/or catheterization in the others. Surgical repair was attempted in three neonates; all three required continued extracorporeal membrane oxygenation support postoperatively because of pulmonary hypertension and severe pulmonary parenchymal disease. One infant died of respiratory insufficiency at 3 months of age. The other two survived and were discharged from the hospital. The diagnostic and therapeutic dilemmas posed by this lesion and the life-saving potential for extracorporeal membrane oxygenation in this rapidly fatal cardiac anomaly are the bases of this report.

Apgar Score↗
PubMed1992

Zinc (Zn2+) blocks voltage gated calcium channels in cultured rat dorsal root ganglion cells.

Dorsal root ganglion cells (DRGs) exhibit 3 types of voltage-dependent calcium channels. We have cultured DRGs from 2- to 4-day-old rat pups and obtained whole-cell patch-clamp recordings of calcium-channel currents after 1-5 days in culture. The calcium-channel currents (carried by barium) were recorded with tetrodotoxin (TTX) in the external solution. A cesium-based solution containing Na-ATP, HEPES and EGTA was used in the recording pipette. Cells were held at -80 mV and calcium channel currents were evoked by stepping to depolarized voltages. The divalent cation zinc (Zn2+) blocked sustained and transient voltage sensitive calcium channel currents. Onset of the blockade was fast and a steady-state was reached within 5-15 min, depending upon the concentration used. The IC50 for inhibition of the peak current evoked by a step depolarization from -80 mV to 0 mV (N plus L channels) for 80 ms was 69 microM Zn2+ and the Hill slope about 1. The calcium current evoked by a voltage step from -80 mV to voltages between -40 mV and -15 mV (T-type current) was more sensitive (> 80% block with 20 microM Zn2+). During wash the effect was only partly reversible in 50% of the neurons. Thus, Zn2+ is a potent blocker of voltage dependent calcium currents in mammalian neurons, especially of T-type currents.

Animals↗
PubMed1992

Effect of calmodulin antagonists on the growth and graviresponsiveness of primary roots of maize.

We examined the effect of calmodulin (CaM) antagonists applied at the root tip on root growth, gravity-induced root curvature, and the movement of calcium across the root tip and auxin (IAA) across the elongation zone of gravistimulated roots. All of the CaM antagonists used in these studies delayed gravity-induced curvature at a concentration (1 micromole) that did not affect root growth. Calmodulin antagonists (> or = 1 micromole) inhibited downward transport of label from 45Ca2+ across the caps of gravistimulated roots relative to the downward transport of 45Ca2+ in gravistimulated roots which were not treated with CaM antagonists. Application of CaM antagonists at the root tip (> or = 1 micromole) also decreased the relative downward movement of label from 3H-IAA applied to the upper side of the elongation zone of gravistimulated roots. In general, tip application of antagonists inhibited neither the upward transport of 45Ca2+ in the root tip nor the upward movement of label from 3H-IAA in the elongation zone of gravistimulated roots. Thus, roots treated with CaM antagonists > or = 1 micromole become less graviresponsive and exhibit reduced or even a reversal of downward polarity of calcium transport across the root tip and IAA transport across the elongation zone. The results indicate that calmodulin-regulated events play a role in root gravitropism.

Biological Transport↗
PubMed1992

The role of calcium in the regulation of hormone transport in gravistimulated roots.

Prior research has shown that gravistimulation induces preferential movement of calcium toward the lower side of the tips of maize roots and that roots depleted of calcium show impaired gravitropism. To further investigate the role of calcium in root gravitropism, we examined the effects of calcium on auxin movement in both vertical and gravistimulated roots of maize. Longitudinal movement of auxin was basipetally polar in intact roots but acropetally polar in decapped roots. Treatment of the root tip with calcium increased basipetal auxin movement in both intact and decapped roots. Gravistimulation induced asymmetric auxin movement toward the lower side of the root tip. Both asymmetric auxin movement and gravicurvature were inhibited by treatment of the root tip with auxin transport inhibitors or with EGTA. The results indicate that there is a close correlation between curvature and gravity-induced asymmetric auxin movement across the root cap. Since gravistimulation causes calcium movement toward the lower side of the root tip, our observation that calcium promotes basipetal auxin movement supports the idea that gravity-induced calcium asymmetry is a key step linking gravistimulation to the establishment of auxin asymmetry during root gravitropism.

Biological Transport↗
PubMed1992

Imaging of hypoxia in human tumors with [F-18]fluoromisonidazole.

Fluoromisonidazole (FMISO) has been shown to bind selectively to hypoxic cells in vitro and in vivo at radiobiologically significant oxygen levels. When labeled with the positron emitter fluorine-18 (F-18), its uptake in tissue can be detected quantitatively with high precision by positron emission transaxial tomography (PETT). This paper presents the first experiences with PETT imaging of [F-18]FMISO uptake in human malignancies, and describes the development of this technique as a tool for the non-invasive assessment of tumor hypoxia. Eight patients with selected cancers were imaged prior to primary radiotherapy, and 3 returned for follow-up scans, for a total of 11 imaging studies. Six of eight pre-radiotherapy studies revealed retention of [F-18]FMISO in tumors that significantly exceeded plasma concentrations by 2 hr after drug injection; all five patients with head and neck primaries had such "positive" scans. An analytic method for the interpretation of [F-18] FMISO PETT images is presented, defining hypoxic elements within a tumor volume as regions with a threshold regional tumor:plasma [F-18]FMISO ratio of greater than or equal to 1.4 by 2 or more hours after injection. Toward the end of a course of fractionated radiotherapy, three repeat studies in patients with initially positive scans showed no tumor accumulation of drug above the threshold ratio of 1.4, suggesting reoxygenation had occurred. Pharmacokinetic and dosimetry data support continued use of [F-18]FMISO as a safe hypoxia probe. Two imaging protocols have been developed for human studies; a long protocol allows for more complete biodistribution and dosimetry information, and a shorter protocol facilitates increased patient accrual by applying a simple, clinically expedient imaging procedure. When correlated with tumor outcome, [F-18]FMISO PETT imaging may be developed as a predictor of tumor response to conventional radiotherapy. The implications of this technique in addressing persistent questions of tumor hypoxia in human oncology is discussed.

Cell Hypoxia↗