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Biomedical subjects

A M Wood

Publications and source records attributed to A M Wood.

At least 19 recordsLinked to original sources
PubMed2005

Juvenile atlantic and shortnose sturgeons (family: Acipenseridae) have different hematological responses to acute environmental hypoxia.

Experiments were conducted to determine the behavioral and physiological responses to acute hypoxic challenges in Atlantic (Acipenser oxyrinchus) and shortnose (Acipenser brevirostrum) sturgeons. We measured the ventilatory rate following a 45-mmHg hypoxic challenge, as well as a variety of hematological parameters, including O2 transport and hormonal, ionic, and metabolic variables, following a 1-h exposure to either 75- or 30-mmHg hypoxic challenges. Compared to fish in normoxic conditions (Pwo2 150 mmHg), juveniles of both species increased their ventilatory rate by approximately 40% when exposed to a 1-h challenge at 45 mmHg Pwo2. Hematological variables (e.g., hematocrit, hemoglobin, and Na+ and Cl- levels) did not change substantially following a 1-h challenge at 75 mmHg Pwo2. Conversely, a severe hypoxic challenge of 30 mmHg caused changes in several hematological variables (e.g., whole blood glucose and plasma cortisol and lactate levels). Most of these hematological parameters returned to prehypoxic levels within 2 h. Severe environmental hypoxia elicited the same basic pattern of response in both species; however, maximal plasma lactate levels were higher in Atlantic sturgeons, and maximal cortisol levels were higher in shortnose sturgeons. Whether these species differences are related to dissimilar hypoxia-tolerance, ecological, and/or endocrinological characteristics between these two species is not entirely clear.

Analysis of Variance↗
PubMed2005

Anomalous unilateral single pulmonary vein: two cases mimicking arteriovenous malformations and a review of the literature.

Total anomalous pulmonary venous drainage is a rare congenital anomaly. It usually involves a pulmonary to systemic venous shunt and most cases have a septal defect in order to survive. Anomalous pulmonary venous drainage with pulmonary venous shunting is an extremely rare and entirely benign entity. We present two such cases, in which there was atresia of the left superior pulmonary vein and drainage via a tortuous collateral vein to the left inferior pulmonary vein. This collateral was mistaken on plain film and CT for a pulmonary arteriovenous malformation. Awareness of this anomalous unilateral single pulmonary vein and its radiological appearances may help in avoiding unnecessary pulmonary angiography.

Adult↗
PubMed2005

Spironucleosis (Hexamitiasis, Hexamitosis) in the ring-necked pheasant (Phasianus colchicus): detection of cysts and description of Spironucleus meleagridis in stained smears.

Trophozoites and cysts of Spironucleus (Hexamita) meleagridis were detected in the intestinal fluid and mucus of pheasant poults with spironudeosis (hexamitiasis, hexamitosis) following staining with Heidenhain iron hematoxylin (HIH) and the Romanowsky-type stain Hemacolor. Their morphology was consistent with that of flagellates of the genus Spironucleus, and bright-field morphologic observations were confirmed by transmission electron microscopy. Cysts occurred mostly within intestinal mucus, which was firmly compressed between microscope slides prior to staining. The internal structures of cysts were similar to those of trophozoites, allowing them to be confidently recognized. Hemacolor provided differential color staining of trophozoites and cysts, allowing accurate identification of S. meleagridis life cycle stages, even in smears in which there was heavy background staining. While HIH often produced dearer and more detailed staining of protozoan structures, in the context of a diagnostic laboratory its use was outweighed by the ease of use, rapidity of results, and differential color staining provided by Hemacolor. The possible significance of a resistant cystic stage in the life cyde of S. meleagridis is discussed.

Animals↗
PubMed2004

Neonatal respiratory morbidity at term and the risk of childhood asthma.

OBJECTIVE: To determine whether neonatal respiratory morbidity at term is associated with an increased risk of later asthma and whether this may explain previously described associations between caesarean delivery and asthma. DESIGN: Retrospective cohort study using Scottish Morbidity Record (SMR) data of maternity (SMR02), neonatal (SMR11), and acute hospital (SMR01) discharges. SETTING: Scotland. PARTICIPANTS: All singleton births at term between 1992-1995 in 23 Scottish maternity hospitals. MAIN OUTCOME MEASURES: Hospital admission with a diagnosis of asthma in the principal position between 1992 and 2000. RESULTS: Children who had a diagnosis of transient tachypnoea of the newborn or respiratory distress syndrome were at increased risk of being admitted to hospital with a diagnosis of asthma (hazard ratio (HR) 1.7, 95% confidence interval (95% CI) 1.4 to 2.2, p<0.001). This association was observed both among children delivered vaginally (HR 1.5, 95% CI 1.1 to 2.0, p = 0.007) and among those delivered by caesarean section (HR 2.2, 95% CI 1.6 to 3.0, p<0.001). In the absence of neonatal respiratory morbidity, delivery by caesarean section was weakly associated with the risk of asthma in childhood (HR 1.1, 95% CI 1.0 to 1.2, p = 0.004). The strengths of the associations were similar whether the caesarean delivery was planned or emergency and were not significantly altered by adjustment for maternal, obstetric, and other neonatal characteristics. CONCLUSIONS: Neonatal respiratory morbidity at term is associated with an increased risk of asthma in childhood which may explain previously described associations between caesarean delivery and later asthma.

Adult↗
PubMed2002

Ultrasound of the thyroid gland in the newborn: normative data.

OBJECTIVE: To establish reference ranges for thyroid length, breadth, depth, and volume in healthy term Scottish infants. DESIGN: Prospective observational study of 100 (49 male) neonates. Length, breadth, and depth were measured, and the volume of each lobe was calculated using the formula for a prolate ellipsoid (volume = length x breadth x depth x pi/6). RESULTS: All measurements showed gaussian distribution, with no significant differences between the right and the left lobes. Values (mean (SD) range) were: length (cm), 1.94 (0.24) 0.9-2.5; breadth (cm), 0.88 (0.16) 0.5-1.4; depth (cm), 0.96 (0.17) 0.6-2.0; volume (ml), 0.81 (0.24) 0.3-1.7; combined volume (ml), 1.62 (0.41) 0.7-3.3. Although there was no difference in mean volume between right and left lobes, there was considerable variation (-0.8 to + 0.7 ml) between the two lobes in individual babies. CONCLUSIONS: Both lobes should be measured to give a combined volume. Our findings provide a reference against which thyroid hypoplasia or goitre can be evaluated.

Female↗
PubMed2001

Rituximab: an innovative therapy for non-Hodgkin's lymphoma.

The epidemiology, etiology, classification, and treatment of non-Hodgkin's lymphoma (NHL) are reviewed, and rituximab, a newly available therapy, is discussed. NHL comprises a group of lymphoproliferative disorders the frequency of which continues to rise. Although many classification systems exist for identifying specific histological subtypes, NHL is generally divided into indolent (low-grade) and aggressive (intermediate- and high-grade) forms. Low-grade NHL is characterized by a slowly progressive, continually relapsing course, with eventual transformation to a more rapidly progressive form that is usually fatal. Several options are available for the management of indolent NHL; none is curative. Rituximab, a human-mouse monoclonal antibody that targets the CD20 antigen expressed in over 90% of B-cell NHLs, provides an alternative to conventional chemotherapy that is relatively safe and effective. In a Phase III trial involving 166 patients with relapsed or refractory low-grade B-cell NHL, rituximab produced an overall response of 48%, with 20 of 80 responders still in remission more than 36 months after treatment. Study results in patients with bulky disease and those requiring retreatment have also been encouraging. Most adverse effects associated with rituximab are mild to moderate. Infusion-related reactions occur more commonly during initial infusions and in patients with evidence of increased tumor burden but can be effectively managed with premedication, supportive care, and adjusted infusion rates. Hematologic effects are generally mild and transient, and adverse immune responses are rare. Rituximab is an alternative to conventional chemotherapy for the treatment of relapsed or refractory low-grade or follicular CD20-positive B-cell NHL.

Animals↗
PubMed2001

Renal arteriography using gadolinium enhanced 3D MR angiography--clinical experience with the technique, its limitations and pitfalls.

Gadolinium enhanced 3D MR angiography (MRA) is becoming a widely accepted technique for imaging the vascular system. We set out to evaluate its accuracy and reliability in visualization of renal arteries in the clinical setting. Gadolinium enhanced MRA was performed in 15 potential live renal donors and 26 patients suspected of having renal artery stenosis who were referred for digital subtraction angiography (DSA). MRA was performed on a 1.5 T MR scanner in a single breath hold. Images from each study were prospectively analysed for demonstration of number of main and accessory renal arteries and degree of renal artery stenosis in a double blind fashion. All the main and accessory arteries were visualized on MRA in the renal donor group, but in one case a branch was not identified owing to breathing artefact. In one case, an extrarenal vascular anomaly was not demonstrated on MRA. In the renal artery stenosis group, sensitivity, specificity and negative predictive values of 96%, 93% and 96% were obtained for clinically significant stenosis (>50%). Gadolinium enhanced MRA proved to be a useful technique in demonstration of renal arterial anatomy and grading of renal artery stenosis. However, we encountered some pitfalls and limitations of the technique during the process. It is important to be aware of these before accepting it as the sole technique in clinical practice.

Adult↗
PubMed2000

Pheasant ataxia: a new condition in pheasant poults.

Between 1995 and 1997 a neurological condition in pheasant poults from 24 sites in England and Scotland was investigated. Affected birds showed varying degrees of ataxia and incoordinated movements and, in severe cases, recumbency, but generally remained alert with their heads held upright. The condition characteristically affected poults from seven weeks of age and the incidence on any one site was low. No significant bacteria were isolated consistently from brain tissue. The condition was characterised histologically by a non-suppurative meningoencephalitis, in which lesions were found predominantly in the cerebellum in 61 of 81 samples examined (75.3 per cent). A non-suppurative myelitis was recorded in 16 of 20 spinal cords examined. No lesions were recorded in peripheral neural tissue and lesions were rare in other tissues. The condition appeared not to have been recorded previously in pheasants. A viral aetiology was suspected but Newcastle disease virus was not involved.

Animals↗
PubMed2000

Metallothionein is expressed in adipocytes of brown fat and is induced by catecholamines and zinc.

Metallothionein (MT) is thought to have an antioxidant function and is strongly expressed during activation of thermogenesis and increased oxidative stress in brown adipose tissue (BAT). Localization and regulation of MT expression in BAT was therefore investigated in rats and mice. Immunohistochemical analysis of BAT from rats exposed to 4 degrees C for 24 h showed that MT and uncoupling protein 1 (UCP1) were coexpressed in differentiated adipocytes, and both cytoplasmic and nuclear localization of MT was observed. Cold induction of MT-1 expression in BAT was also observed in mice. Administration of norepinephrine to rats and isoproterenol to mice stimulated MT and UCP1 expression in BAT, implying a sympathetically mediated pathway for MT induction. In mice, zinc, and particularly dexamethasone, induced MT-2 expression in BAT and liver. Surprisingly, zinc also induced UCP1 in BAT, suggesting that elevated zinc may induce thermogenesis. We conclude that expression of MT in mature brown adipocytes upon beta-adrenoceptor activation is consistent with a role in protecting against physiological oxidative stress or in facilitating the mobilization or utilization of energy reserves.

Adaptation, Physiological↗
PubMed2000

Metallothionein gene expression and secretion in white adipose tissue.

White adipose tissue (WAT) has been examined to determine whether the gene encoding metallothionein (MT), a low-molecular-weight stress response protein, is expressed in the tissue and whether MT may be a secretory product of adipocytes. The MT-1 gene was expressed in epididymal WAT, with MT-1 mRNA levels being similar in lean and obese (ob/ob) mice. MT-1 mRNA was found in each of the main adipose tissue sites (epididymal, perirenal, omental, subcutaneous), and there was no major difference between depots. Separation of adipocytes from the stromal-vascular fraction of WAT indicated that the MT gene (MT-1 and MT-2) was expressed in adipocytes themselves. Treatment of mice with zinc had no effect on MT-1 mRNA levels in WAT, despite strong induction of MT-1 expression in the liver. MT-1 gene expression in WAT was also unaltered by fasting or norepinephrine. However, administration of a beta(3)-adrenoceptor agonist, BRL-35153A, led to a significant increase in MT-1 mRNA. On differentiation of fibroblastic preadipocytes to adipocytes in primary culture, MT was detected in the medium, suggesting that the protein may be secreted from WAT. It is concluded that WAT may be a significant site of MT production; within adipocytes, MT could play an antioxidant role in protecting fatty acids from damage.

Adipocytes↗
PubMed1999

Hemodynamic effects of basal and stimulated release of endogenous nitric oxide in isolated human lungs.

Background-We compared the hemodynamic responses to inhibition or stimulation of endothelial nitric oxide (NO) release of isolated explanted lungs from transplantation recipients with pulmonary hypertension and in normotensive unallocated donor lungs. Methods and Results-Lungs from 10 patients with severe pulmonary hypertension (SPH) and from 16 patients with severe chronic obstructive lung disease (COLD) were studied. Fourteen normotensive lungs were studied as controls. The lungs were perfused at a constant flow. In protocol 1 N(G)-nitro-L-arginine methyl ester caused a similar rise in baseline pulmonary artery pressure (PAP) that was similar in SPH (+17.1+/-4.2 mm Hg; n=5), COLD (+15.5+/-4.8 mm Hg; n=8), and control lungs (+14.5+/-1.5 mm Hg; n=7). Arterial occlusion demonstrated that most of the changes with N(G)-nitro-L-arginine methyl ester were precapillary. The response to sodium nitroprusside (10(-8) to 10(-4) mol/L) was similar in all groups. In protocol 2, the lungs were preconstricted, and acetylcholine (10(-9) to 10(-5) mol/L) caused a lesser fall in PAP in both COLD and SPH lungs compared with control (-41.9+/-8.6%, -55. 7+/-7.6%, and -73.2+/-2.5%, respectively; P<0.05), whereas sodium nitroprusside (10(-5) mol/L) decreased PAP to initial levels in all lungs. Conclusions-Stimulated release of NO is impaired in arteries of lungs with plexogenic or hypoxemic pulmonary hypertension. In contrast, basal release of NO appears to be maintained.

Acetylcholine↗
PubMed1999

Rat metallothionein-2 contains N(alpha)-acetylated and unacetylated isoforms.

Mammalian metallothioneins (MT), are characteristically N(alpha)-acetylated and the presence of an unblocked N-terminus has not previously been reported. On-line capillary electrophoresis-electrospray mass spectrometry of hepatic MT-2 from rats injected with zinc revealed two isoforms differing by a mass equivalent to that of a single acetyl group. The lower mass component constituted > 20% of total MT-2 protein and both MT-2 isoforms were separated by reversed-phase high-performance liquid chromatography. The identity of each fraction was confirmed by matrix-assisted laser desorption ionisation mass spectrometry, and amino acid analysis and N-terminal sequencing revealed that the lower mass isoform was unblocked at the N-terminus and had an amino acid composition and sequence which is characteristic of rat MT-2. Thus the complementary techniques of mass spectrometry and N-terminal sequencing demonstrated conclusively that purified MT-2 from zinc-treated rats contains an unacetylated isoform. We propose that the cotranslational acetylation of rat MT-2 may under some circumstances be inefficient compared to that in other nonrodent species, where we have detected only trace levels of unacetylated MT isoforms.

Acetylation↗
PubMed1999

Suspected ifosfamide-induced neurotoxicity.

Ifosfamide is an antineoplastic agent that requires hepatic activation to the cytotoxic active metabolite ifosforamide mustard. During metabolism, the byproduct, chloroacetaldehyde, which is structurally similar to both chloral hydrate and acetaldehyde, is produced. Secondary to its ability to cross the blood-brain barrier, this metabolite may be responsible for the neurotoxicity observed with ifosfamide. Any case of suspected ifosfamide-induced neurotoxicity, together with a decision to treat, must be determined on an individual patient basis. The differential diagnosis should include infection, laboratory abnormalities, and concomitant drugs. At this time, literature to support treatment modalities such as intravenous albumin and methylene blue is minimal.

Adult↗
PubMed1999

UV filter compounds in human lenses: the origin of 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid O-beta-D-glucoside.

PURPOSE: To investigate UV filter synthesis in the human lens, in particular the biosynthetic origin of the second most abundant UV filter compound, 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid O-beta-D-glucoside. METHODS: Human lenses were analyzed by high-performance liquid chromatography (HPLC) after separate incubation with 3H-tryptophan (3H-Trp), beta-benzoylacrylic acid, D,L-alpha-amino-beta-benzoylpropionic acid, or D,L-3-hydroxykynurenine O-beta-D-glucoside. The effect of pH on the model compound D,L-alpha-amino-beta-benzoylpropionic acid and D,L-3-hydroxykynurenine O-beta-D-glucoside was also investigated. RESULTS: UV filters were not detected in fetal lenses, despite a 5-month postnatal lens displaying measurable levels of UV filters. In adults no radiolabel was incorporated into 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid O-beta-D-glucoside after 3H-Trp incubations. Beta-benzoylacrylic acid was readily reduced in lenses. D,L-alpha-amino-beta-benzoylpropionic acid and D,L-3-hydroxykynurenine O-beta-D-glucoside slowly deaminated at physiological pH and were converted to beta-benzoylpropionic acid and 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid O-beta-D-glucoside, respectively, after lens incubations. CONCLUSIONS: UV filter biosynthesis appears to be activated at or near birth. Compounds containing the kynurenine side chain slowly deaminate, and in the lens, the newly formed double bond is rapidly reduced. These findings suggest that 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid O-beta-D-glucoside is derived from L-3-hydroxykynurenine O-beta-D-glucoside through this deamination-reduction process. The slowness of the deamination presumably accounts for the absence of incorporation of radiolabel from 3H-Trp into 4(2-amino-3-hydroxyphenyl)4-oxobutanoic acid O-beta-D-glucoside.

Acrylates↗