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Biomedical subjects

M Davenport

Publications and source records attributed to M Davenport.

At least 19 recordsLinked to original sources
PubMed2006

Effects of gonadectomy on performance in operant tasks measuring prefrontal cortical function in adult male rats.

Previous studies have shown that gonadectomy in adult male rats influences the acquisition and performance of spatial and other working memory tasks that depend in part on the medial prefrontal cortex and its dopamine innervation. Stimulated by previous findings that gonadectomy alters dopamine axon density in not only medial but several other prefrontal fields, the present studies asked whether gonadectomy might also broadly impact dopamine-dependent prefrontal functions, and whether these effects bore any relation to hormone modulation of mesoprefrontal dopamine afferents. Specifically, control, gonadectomized, and gonadectomized rats given estradiol or testosterone propionate were tested on a series of operant tasks that together measured medial prefrontal functions of spatial working memory, impulsivity and extradimensional set shifting and orbital prefrontal functions of reversal learning/perseveration and motivation. Afterwards, animals were sacrificed, their bulbospongiosus muscles were removed and weighed, their brains were processed for immunocytochemistry for the dopamine-synthesizing enzyme tyrosine hydroxylase, and axon densities were measured in orbital and medial prefrontal fields. Statistical evaluations of group effects on behavior and regression analyses comparing individual performance with muscle weights and axon density measures revealed androgen-reversible effects of gonadectomy on acquisition of spatial working memory and extradimensional set shifting that were correlated with bulbospongiosus weight and medial prefrontal dopamine axon density, estrogen-sensitive influences of gonadectomy on motivation and response withholding that were correlated with bulbospongiosus weight but not with dopamine innervation, and still other prefrontal functions, i.e., impulsivity, reversal learning, that were insensitive to gonadectomy and unrelated to gonadectomy-induced changes in muscle weight or prefrontal dopamine innervation.

Afferent Pathways↗
PubMed2005

First results from the CERN axion solar telescope.

Hypothetical axionlike particles with a two-photon interaction would be produced in the sun by the Primakoff process. In a laboratory magnetic field ("axion helioscope"), they would be transformed into x-rays with energies of a few keV. Using a decommissioned Large Hadron Collider test magnet, the CERN Axion Solar Telescope ran for about 6 months during 2003. The first results from the analysis of these data are presented here. No signal above background was observed, implying an upper limit to the axion-photon coupling g(agamma)<1.16x10(-10) GeV-1 at 95% C.L. for m(a) less, similar 0.02 eV. This limit, assumption-free, is comparable to the limit from stellar energy-loss arguments and considerably more restrictive than any previous experiment over a broad range of axion masses.

Journal Article↗
PubMed2005

Metacarpophalangeal pattern profile analysis as a tool for early diagnosis of Turner syndrome.

PURPOSE: To analyze the metacarpophalangeal pattern profile (MCPP) in a cohort of individuals with Turner syndrome (TS), and to assess its value as a tool for early diagnosis of TS. MATERIAL AND METHODS: Medical records and radiological material were collected of 71 patients with TS aged between 3 and 21 years. Forty-six patients received growth hormone therapy (33-66 microg kg(-1) day(-1)) and 14 of these were also treated with the anabolic steroid oxandrolone (1.25-3.75 mg day(-1)). A total of 233 frontal hand radiographs were studied and pattern profiles were calculated. Profiles of the TS patients were compared with those of 70 normal females. Mean pattern profiles were calculated for different age groups and extrapolated profiles for newborns and infants were developed. RESULTS: Our results confirm that patients with TS have a distinct MCPP which differs significantly from that of normal individuals. A bone-shortening gradient with increasing shortening from distal phalanges to metacarpals was demonstrated. We also showed that the MCPP in TS is a remarkably constant feature from 3 to 18 years. Pattern profiles did not differ significantly between the patients with 45,X and non-45,X karyotype. MCPP was not affected by treatment with growth hormone of growth hormone plus oxandrolone. Discriminant analysis yielded correct classification in 88%, of analyzed cases. CONCLUSION: TS individuals have a distinct hand pattern profile that is not age-related. MCPP analysis can be applied at any age and may facilitate early diagnosis of TS. Our study showed that MCPP analysis is a specific and sensitive method that should be considered as a routinely used tool for early diagnosis of TS in girls with unexplained short stature.

Adolescent↗
PubMed2004

The outcome of the older (> or =100 days) infant with biliary atresia.

BACKGROUND: There is a detrimental effect of increasing age on the results of the Kasai portoenterostomy for biliary atresia (BA), and some centers routinely advocate primary liver transplantation for the older infant, irrespective of other criteria. This perception that such infants are indeed irretrievable was tested by retrospective analysis. METHODS: All infants who had undergone surgery for BA during the period 1980 through 2000 aged > or =100 days were reviewed. Actuarial survival was calculated using 2 end-points (death and transplantation). A retrospective review of their ultrasonography (n = 12) and preoperative liver histology (n = 22) was also undertaken to ascertain possible predictive criteria. RESULTS: A total of 422 infants had BA diagnosed during this period, of which 35 (8.2%) were > or =100 days at surgery (median [interquartile range], 133 [range, 108 to 180] days). Surgery included portoenterostomy (n = 26), hepaticojejunostomy (n = 7), and a resection and end-to-end anastomosis (n = 1). A laparotomy only was performed in 1. Five- and 10-year actuarial survival rate with native liver was 45% and 40%, respectively. Currently, 12 (35%) patients are alive with their native liver (8 are anicteric), 9 (28%) have undergone transplantation, and 13 have died. Although there were some survival advantages for types 1 or 2 BA and "noncirrhosis" at time of surgery, neither reached statistical significance. Individual histologic features (eg, degrees of fibrosis, giant cell transformation, bile duct destruction) in the retrospective review of available material were not discriminatory. The finding of a "heterogeneous" parenchyma on ultrasonography was predictive of poor outcome but lacked sensitivity. CONCLUSIONS: The potential for reasonable medium-term survival is present in about one third of infants 100 days or older coming to primary corrective surgery. In the absence of accurate discrimination, the authors continue to favor this option rather than subject all to transplant simply on the basis of age.

Abnormalities, Multiple↗
PubMed2004

Galactocele in a male infant with congenital hypopituitarism.

Galactocele is an uncommon benign breast lesion usually occurring in young lactating women. It is a rare cause of breast enlargement in children. We report a galactocele in a male child with congenital hypopituitarism and propose an association between the two conditions.

Breast Cyst↗
PubMed2003

Benefits and risks of calcium resonium therapy in hyperkalaemic preterm infants.

UNLABELLED: The occurrence of an intestinal perforation in a prematurely born infant following rectal administration of a calcium resonium resin prompted a literature review to determine whether use of resins in neonates was evidence based. This revealed that the results of anecdotal series suggested that resins were useful, but the only randomized trial including prematurely born infants demonstrated that resins were less efficacious than glucose and insulin infusions. Important side effects were reported including colonic necrosis and impaction with perforation. CONCLUSION: The risks and benefits of exchange resins in prematurely born infants should be assessed in an appropriately sized randomized trial.

Humans↗
PubMed2002

Dose related association of impact activity and bone mineral density in pre-pubertal girls.

Impact activity is an important contributor to bone accrual. Children engaging in such activity have been shown to have greater bone mineral density (BMD) than their peers. This cross-sectional study was designed to quantify the association between BMD and impact activity in pre-pubescent girls, specifically examining for a dose-dependent relationship. Fifty 7-11-year-old Caucasian female gymnasts were grouped by hours of gymnastics participation during a 6-month period: LOW, 1-8 hours/week (hrs/wk); HIGH, >8 hrs/wk. They were compared with 20 controls, with height, weight, age, and Tanner stage averages matched to the gymnasts. Total body, forearm, hip, lumbar spine BMD, and body composition were measured by dual energy X-ray absorptiometry (DXA). Strength was measured by one repetition maximum testing, calcium intake was quantified by questionnaire, and physical activity was measured by questionnaire and activity monitors. Total and regional BMD were greater in the HIGH group than the controls (P<0.05). Furthermore, both total and forearm BMD were greater in the HIGH group than in the LOW group, and greater in the LOW group than in the controls (P<0.05). Simple regression analysis between hrs/wk of gymnastics activity versus total and regional BMD (using maturation-adjusted Z scores) yielded a positive slope for each site. R2 was greatest for hip BMD (R2 = 0.25), and least for lumbar spine (R2 = 0.10) (P<0.0001). In conclusion, in this group of pre-pubescent girls, we observed a dose-dependent relationship between BMD and hrs/wk of impact activity; even moderate doses of impact activity were associated with increased BMD.

Bone Density↗
PubMed2002

Intestinal permeability and absorptive capacity in children with portal hypertension.

BACKGROUND: Portal hypertension may affect intestinal function leading to malnutrition in children with liver disease. The aim was to determine whether children with portal hypertension with or without liver disease had impaired absorptive capacity and intestinal barrier function (intestinal permeability) and to ascertain whether these abnormalities related to changes in body composition. METHODS: Twenty-six children with portal hypertension were divided according to aetiology into: Group 1 intrahepatic (n = 15) and Group 2 prehepatic (n = 11). Thirty-five children acted as controls. Carbohydrate absorption and intestinal permeability were assessed using a sugar absorption/permeability test and a variety of anthropometric measurements were obtained. RESULTS: 3-O-methyl-D-glucose, D-xylose and L-rhamnose excretion were significantly reduced in both patient groups compared to controls (P < or = 0.008) and the differential urinary excretion of melibiose/rhamnose (intestinal permeability) was significantly increased in Group 1 only (P < 0.05). Anthropometric measurements showed low Z scores in both groups, but there was no significant (P > 0.05) difference between them. There was no significant correlation between urinary excretion of sugars. anthropometric measurements and energy intake. CONCLUSIONS: Increased portal pressure reduces the absorptive capacity of the small intestine, while liver disease itself leads to increased intestinal permeability.

Adolescent↗
PubMed2001

Immunohistochemistry of the liver and biliary tree in extrahepatic biliary atresia.

BACKGROUND: Progressive destruction of intrahepatic bile ducts may determine outcome in extrahepatic biliary atresia (EHBA) despite successful portoenterostomy. The aim of this study was to characterize the inflammatory infiltrate of a large series of cases of biliary atresia and relate these findings to clinical outcome. METHODS: Immunohistochemical analysis was performed on frozen tissue sections of extrahepatic biliary tree and liver biopsies obtained (August 1996 to March 1998) from 28 infants with EHBA and 8 liver biopsy specimens from age-matched controls with other cholestatic liver disorders. A semiquantitative scoring system was designed to evaluate the staining with a panel of antibodies to the CD4, CD8, CD25, CD56, CD68, CD71 antigens and to HLA-DR, ICAM-1, VCAM-1, E-selectin and LFA-1. The infants then underwent followup prospectively and divided into 2 prognostic groups at 12 months postoperatively: those who had cleared their jaundice (graded as a good outcome [n = 19]), and those who required liver transplantation or who had failed to clear their jaundice (defined as > 50 micromol/L; graded as poor outcome [n = 9]). RESULTS: CD4(+) lymphocytes and CD56(+) (NK cells) predominated in the liver of infants with EHBA as compared with controls. The infiltrating cells exhibited marked proliferation (CD71 expression) and activation (particularly LFA-1 but also CD25 expression). A smaller subpopulation of the cells also expressed VCAM and E-selectin. HLA-DR was strongly expressed on Kupffer cells and to a lesser extent on proliferating bile ducts and sinusoidal endothelium. Expression of the majority of markers was lower in the remnant bile duct tissue than in the liver of EHBA (P <.05) with only HLA-DR and LFA-1 (on infiltrating cells) and ICAM (on endothelium) expressed strongly in the remnant bile duct tissue. Although quantitatively less pronounced, all of these immunohistochemical features also were noted in non-EHBA cholestatic liver tissue. A good outcome at 12 months was associated with lower CD68 (macrophage) expression in both the liver (P <.05) and biliary tree (P <.05) and with reduced expression of ICAM-1 (P =.05) on infiltrating cells in the biliary remnant. CONCLUSIONS: Immunohistochemical patterns of immune-mediated liver injury and inflammation were prevalent features at the time of portoenterostomy. They were neither exclusive to nor characteristic of EHBA. A reduction in the expression of the macrophage marker (CD68) within the liver and biliary remnants and reduction of ICAM-1 expression on infiltrating cells in the biliary remnants appear to be associated with a better postoperative prognosis.

Antigens, CD↗
PubMed2001

Closed gastroschisis: Antenatal and postnatal features.

Four cases of antenatally diagnosed gastroschisis are described in whom there was significant closure of the abdominal wall defect around the prolapsed midgut. In 2 cases this resulted in near-total midgut infarction and short bowel syndrome. In a further case there was entry and exit jejunal and colonic atresia and significant midgut damage but some viability of extrabdominal bowel. In the final case, although there was complete closure of the ring around the base of the midgut, no intestinal loss had occurred. In the latter 2 cases, serial antenatal ultrasound imaging had shown development of intrabdominal bowel dilatation prompting early preterm delivery. Three of these infants currently are alive and well. The authors suggest the use of the term closed (or closing) gastroschisis to describe this phenomenon. J Pediatr Surg 36:1834-1837.

Female↗
PubMed2001

Recommendations for the diagnosis and management of Turner syndrome.

Comprehensive recommendations on the diagnosis of Turner syndrome (TS) and the care of affected individuals were published in 1994. In the light of recent advances in diagnosis and treatment of TS, an international multidisciplinary workshop was convened in March 2000, in Naples, Italy, in conjunction with the Fifth International Symposium on Turner Syndrome to update these recommendations. The present paper details the outcome from this workshop. The genetics and diagnosis of the syndrome are described, and practical treatment guidelines are presented.

Adolescent↗
PubMed2000

Size reduction of small bowels from adult cadaveric donors to alleviate the scarcity of pediatric size-matched organs: an anatomical and feasibility study.

BACKGROUND: Small bowel transplantation in children weighing less than 10 kg is hindered by the lack of size-matched donors. The ability to create reduced size small bowel grafts from adult cadaveric donors suitable for use in young children has been studied. METHODS: Volumetric assessment of computed tomography scans were used to evaluate abdominal cavity and small bowel volumes in children. Small bowels were retrieved from adult cadaveric donors and reduced in size. RESULTS: Computed tomography studies of the abdominal cavity showed that the mean volume available for a small bowel graft was 260 ml in children less than 5 kg (n = 5) and 460 ml in children weighing 5-10 kg (n = 5). Fifteen small bowels were successfully reduced to provide an ileal graft of one meter while keeping the whole length of the superior mesenteric artery and vein after their dissection in the proximal part of the mesentery. The mean volume of the grafts created was 270 ml in seven thin patients (body mass index [BMI] <25), 390 ml in five preobese patients (25< BMI<30), and 490 ml in three obese patients (BMI>30). Mesenteric transillumination in thin donors allowed safe dissection and complete hemostasis. No diameter reduction was required. Technical modifications permitted the creation of two grafts, one ileal and the other jejunal from a single donor. Volumetric and surgical data show that implantation of up to two meters of ileum from a thin adult weighing up to 80 kg is feasible in children weighing less than 10 kg. CONCLUSION: Size reduction of adult cadaveric small bowels can provide suitable grafts for children of less than 10 kg and could expand the potential pool of donors for these patients.

Adult↗
PubMed2000

Morbidity in infants with antenatally-diagnosed anterior abdominal wall defects.

The aims of this study were to compare the morbidity of infants with gastroschisis (GS) with that of infants with exomphalos (EX) without lethal abnormalities and to identify factors predictive of adverse outcome: a requirement for parenteral nutrition (PN) for over 1 month and hospital admission for over 2 months. The medical records of 45 infants with anterior wall defects (32 with GS) diagnosed antenatally who consecutively received intensive care in one institution from 1993 were reviewed. Both the GS and EX infants had a median gestational age of 37 weeks, but the former were lighter at birth (P < 0.01). Fourteen infants (all with GS) were able to start feeds only after 2 weeks; 10 (8 with GS) developed liver dysfunction; and 5 (all with GS) died. The GS compared to the EX infants required a longer period of PN (median 20 vs 10 days, P < 0.01) and longer hospital admission (median 40 vs 25 days, P < 0.01). In the GS group the time to start feeding related independently to prolonged hospital stay, and the existence of structural bowel abnormalities (SBA) related independently to both measures of adverse outcome, with a positive predictive value of 100%. We conclude that infants with GS, particularly those with SBA, suffer greater morbidity than infants with EX without lethal abnormalities.

Enteral Nutrition↗
PubMed2000

Prediction of outcome by computer-assisted analysis of lung area on the chest radiograph of infants with congenital diaphragmatic hernia.

BACKGROUND/PURPOSE: Pulmonary hypoplasia is a major cause of mortality and morbidity in infants with congenital diaphragmatic hernia (CDH). Pulmonary hypoplasia is characterized by low volume lungs, and affected infants are likely to have a low lung area on their chest radiograph. The authors assessed whether, in CDH infants, computer-assisted analysis of the chest radiograph lung area gave an accurate indication of lung volume, and if a low lung area was a better predictor of poor outcome (death or oxygen dependency at 28 days) than other test results. METHODS: Comparisons were made of the radiographic lung area derived by computer-assisted analysis and lung volume, assessed by measurement of functional residual capacity (FRC) on day 1 before surgical intervention and on the first postoperative day. Compliance was measured, and the maximum and modified ventilation indices and maximum Paco2 also was noted. Twenty-five CDH infants with a median gestational age of 38 weeks were studied; 18 had FRC measurements preoperatively. RESULTS: Both preoperatively and postoperatively, the lung areas and FRCs correlated significantly (r = 0.51, P<.05; r = 0.76, P<.02, respectively). Eleven infants had a poor outcome (5 infants died without an operation); that group preoperatively differed significantly from those with a good outcome with respect to having a lower compliance (P<.02) and higher maximum ventilation index (P<.01) and maximum modified ventilation index (P<.05). Only postoperatively did infants with a poor outcome versus good outcome have a significantly lower lung area (P<.05); they also had a lower increase in lung area preoperatively to postoperatively (P<.01). Receiver operator characteristic curves were constructed; comparison of the areas under the curves showed that preoperatively, a low compliance and high ventilation index were the best predictors of poor outcome. Postoperatively, a low lung area performed as well as the ventilation indices. CONCLUSION: Computer-assisted analysis of the lung area on the chest radiograph is useful in predicting outcome in CDH infants postoperatively but not preoperatively.

Hernia, Diaphragmatic↗
PubMed2000

Striated muscle cells in non-neoplastic lung tissue: a clinicopathologic study.

This study was performed to study the prevalence, origin, and clinical implication of striated muscle cells in congenital non-neoplastic lung abnormalities. Five cases of striated muscle cell proliferation within congenital non-neoplastic pulmonary abnormalities were identified from a series of 31 (16%) resected specimens obtained at King's College Hospital, London, during the period 1992 to 1998. Lung tissue was also obtained from 48 normal human fetuses and serial sections stained for the presence of striated muscle. A histologic and immunohistochemical study of the clinical cases and the fetal material was performed by using phosphotungstic acid hematoxylin staining and immunostaining for myoglobin and desmin. Striated muscle cells were identified either as a diffuse or a focal proliferation within the lung interstitia of five infants. The congenital lung anomalies were intra-abdominal pulmonary sequestration associated with congenital cystic adenomatoid malformation (CCAM), intrathoracic sequestration again with features of CCAM, an intrathoracic sequestration associated with a congenital diaphragmatic hernia, and 2 Stocker type II intrathoracic CCAMs. Striated muscle cells were not identified in any section of lung tissue derived from the fetal series. Striated muscle cells proliferation in non-neoplastic lung tissue is more common than usually reported. Although the exact origin of such cells is speculative, because it is always detected within pulmonary anomalies, a wide morphogenetic error is likely. The clinical implication of its presence has to be further defined. HUM PATHOL 31:1477-1481.

Adult↗