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J M Davison

Publications and source records attributed to J M Davison.

At least 19 recordsLinked to original sources
PubMed2004

Sex and the pregnant kidney: does renal allograft gender influence gestational renal adaptation in renal transplant recipients?

BACKGROUND: Animal work indicates that ovarian hormones are important in initiating and maintaining enhanced renal function in pregnant rats and that a renal response resembling pregnancy can be provoked in male rats exposed to pregnancy hormones. Women becoming pregnant following renal transplantation provide an opportunity to compare the functional response of male and female allografts to the gestational endocrine environment. METHODS: This retrospective observational study included 20 renal allograft recipients (age 29.7 +/- 2.4 yrs) (mean +/- SE) who had 22 pregnancies beyond 24 weeks (gestation at delivery 35.5 +/- 0.6 weeks). Donor characteristics, transplant details, renal follow-up data, and information about pregnancy and allograft function were obtained from hospital notes. RESULTS: Thirteen women received male allografts (donor age 30.0 +/- 3.9 years) (mean +/- SEM) and 7 women, female allografts (donor age 45.1 +/- 6.0 years) (P = .04). There were no significant differences between the two groups in maternal recipient age, transplant to pregnancy interval, antenatal complications, pregnancy outcome, or postnatal graft function. Compared to prepregnancy values serum creatinine (SCr) decrements and augmented 24-hour creatinine clearance (CrCl) were observed over the first trimester in both male and female allografts: Delta CrCl from 106.8 +/- 13.2 mL/min to 114.4 +/- 11.4 mL/min (35.6% increase) and 71.8 +/- 7.4 to 89.5 +/- 11.3 mL/min (24.7% increase), respectively, and Delta SCr from 90.1 +/- 5.4 micromol/L to 73.6 +/- 6.6 micromol/L (17.8% decrease) and 99.8 +/- 9.7 micromol/L to 78.0 +/- 5.7 micromol/L (13.5% decrease), respectively. Differences between the two groups did not reach statistical significance. CONCLUSIONS: Donor gender and/or age do not appear to influence the gestational renal response in kidney transplant recipients.

Adult↗
PubMed2002

Clinical outcomes of pregnancy in women with type 1 diabetes(1).

OBJECTIVE: To evaluate predictors of neonatal hypoglycemia and macrosomia in 107 consecutive pregnancies in type 1 diabetic women. METHODS: We conducted a case record analysis of singleton type 1 diabetic pregnancies between January 1994 and January 1999 following institution of standardized management. RESULTS: The duration of diabetes in the women was 12.9 +/- 6.8 years, and 44 were primigravidas. The mean HbA1c throughout pregnancy was 7.2 +/- 0.8%. There was no relationship between neonatal blood glucose (checked before the second feed) and HbA1c at any point in pregnancy or mean pregnancy HbA1c (R = 0.20, P >.1). However, there was a negative correlation between neonatal blood glucose and maternal blood glucose during labor (R = -0.33, P <.001). When maternal blood glucose during labor was greater than 8 mM (144 mg/dL), neonatal blood glucose was usually less than 2.5 mM (mean 1.7 +/- 0.4 mM or 31 mg/dL). There was no relationship between mean HbA1c and birth weight (R = 0.02, P >.1) or between maximum insulin dose and birth weight (R = 0.09, P >.1). Fetal abdominal circumference measured by ultrasound at 34 weeks correlated strongly with birth weight (R = 0.72, P <.001). CONCLUSION: Neonatal hypoglycemia correlates with maternal hyperglycemia in labor, not with HbA1c during pregnancy. Macrosomia does not correlate with HbA1c during pregnancy.

Adolescent↗
PubMed2002

The role of arginine vasopressin in human labour: functional studies, fetal production and localisation of V1a receptor mRNA.

OBJECTIVE: To investigate labour-associated changes in: 1. the myometrial contractile response to arginine vasopressin compared with oxytocin in vitro 2. fetal production of arginine vasopressin and 3. myometrial vasopressin V1a receptor mRNA. DESIGN: The contractile response to vasopressin (compared with oxytocin) was investigated in paired myometrial strips in vitro. Blood was taken from the umbilical artery and vein at delivery and arginine vasopressin measured by radio-immunoassay. V1a receptor mRNA was determined by in situ hybridisation. RESULTS: Myometrium was more sensitive to arginine vasopressin than oxytocin (P<0.05 for frequency, amplitude and activity integral in paired strips) after, but not before labour. There was a marked umbilical arteriovenous difference in arginine vasopressin concentration at delivery suggesting fetal production which was not influenced by labour. Myometrial vasopressin V1a receptor mRNA was not increased after the onset of labour. CONCLUSIONS: The human uterus is extremely sensitive to arginine vasopressin in vitro. Arginine vasopressin is produced by the fetus but fetal formation is not increased during labour.

Adult↗
PubMed2002

Glomerular heteroporous membrane modeling in third trimester and postpartum before and during amino acid infusion.

Human pregnancy is associated with substantial increments in glomerular filtration rate (GFR) and renal plasma flow (RPF). We have previously demonstrated that permselectivity to neutral dextrans is altered in pregnancy, theoretical analysis of the dextran sieving curves suggesting that elevated GFR is due to increased RPF and decreased glomerular oncotic pressure (pi(GC)) with no evidence of increased transglomerular hydrostatic pressure difference (DeltaP). These conclusions have been challenged, with claims that the rise in GFR is primarily a result of a decrement in pi(GC). With refined laboratory and infusion protocols, we have reexplored the determinants of ultrafiltration in a serial study of 11 healthy women in late pregnancy (LP) and 4 mo postpartum (PP), both in the baseline state and after increasing GFR and RPF by infusion of amino acids. Results were analyzed using two computer modeling programs. Increased GFR in LP (38%, P < 0.05) was due to a combination of elevated RPF (22%) and a decrement in pi(GC) and associated with an increased ultrafiltration coefficient, without evidence of increased DeltaP, and additional amino acid-provoked GFR increments (P < 0.05) produced similar findings. In addition, refined methodology permitted collection of sufficient data on excreted large-radii dextrans (>60 A) to better define the nondiscriminatory "shunt" pathway (omega(0)) and the standard deviation of pore size (S) about the mean radius of the distribution. Thus it was possible to demonstrate that the physiological increase in total protein excretion in LP is associated with a prominent shunt and an upward shift in breadth of distribution of pore sizes. This ability to quantify omega(0) and S will now permit better evaluation of the pathophysiological changes in the glomerulus associated with pregnancy in women with renal disease and in gravidas developing preeclampsia.

Adult↗
PubMed2001

Altered osmotic thresholds for arginine vasopressin secretion and thirst during superovulation and in the ovarian hyperstimulation syndrome (OHSS): relevance to the pathophysiology of OHSS.

OBJECTIVE: To test the hypothesis that decreases in and maintenance of a new steady state in plasma osmolality and sodium level in ovarian hyperstimulation syndrome (OHSS) are due to altered osmoregulation of arginine vasopressin secretion and thirst. DESIGN: Prospective study. SETTING: IVF-ET program in a university-based assisted reproductive treatment center. PATIENT(S): Eight women undergoing superovulation for IVF-ET and five women with normal menstrual cycles. INTERVENTION(S): Two-hour infusion of 5% saline on day 3 or 4 after hCG administration in patients undergoing IVF or in the early luteal phase in controls. A 5% saline infusion test was done on day 10 after hCG administration in one patient with OHSS and one patient without OHSS, both of whom were undergoing IVF. MAIN OUTCOME MEASURE(S): Comparison of changes in thresholds for thirst and plasma vasopressin to plasma osmolality. Changes in urine osmolality, plasma electrolytes, hemoglobin level, and hematocrit were assessed at baseline and during infusion of 5% saline. RESULT(S): The sensitivity of the changes in arginine vasopressin secretion and thirst after 5% saline infusion was similar in IVF patients on day 3 or 4 after hCG and controls. However, the osmotic threshold was significantly lower by 6 mOsm/kg in IVF patients. By day 10 after hCG, the lower osmotic thresholds for arginine vasopressin secretion and thirst persisted in OHSS, although the sensitivity to arginine vasopressin secretion was markedly reduced. CONCLUSION(S): The osmotic thresholds for arginine vasopressin secretion and thirst are reset to lower plasma osmolality during superovulation for IVF-ET. This new lower body tonicity is maintained until at least day 10 after hCG in OHSS. Decreases in plasma osmolality and plasma sodium levels in OHSS are due to altered osmoregulation rather than electrolyte losses; correction of apparent "electrolyte imbalance" in OHSS is therefore inappropriate.

Adult↗
PubMed2001

The kidney and hypertension in pregnancy: twenty exciting years.

Before 1980 research on the kidney and hypertension during pregnancy was neglected, although these diseases, especially hypertension, are major causes of morbidity to mother and child. The past 20 years, however, has witnessed a striking reversal of this neglect. This review focuses on recent progress in renal physiology, kidney disease, and hypertension as relates to pregnancy. Why do renal hemodynamics increase markedly in pregnancy? Studies have suggested roles for nitric oxide synthase, prostaglandins, endothelin and relaxin. This area of research is exciting, as unraveling why glomerular filtration rate and renal plasma flow increase in pregnancy may eventually help all patients with acute and chronic renal function loss. Concerning other advances: Micropuncture studies in rats, and the interpretation of fractional dextran clearances in humans show that the hyperfiltration that occurs during normal gestation is not associated with increased glomerular capillary pressure. Finally, description of changes in osmoregulation and in the metabolic disposal of arginine vasopressin in human pregnancy led to identification and appropriate treatment of a new group of disorders termed "transient diabetes insipidus of pregnancy." Chronic renal disease of any severity once led to proscription or interrupting of pregnancy. Clinical-pathological correlation studies and long-term follow-up of the mothers have revealed that most of these gestations succeed with little risk of worsening the natural history of the kidney disorder. This is also true in allograft recipients, and we now have guidelines to counsel both groups of patients. Progress relating to hypertension in pregnancy has been in 2 broad areas; systematic attempts to accurately define and differentiate the various disorders and population studies to predict, prevent, and improve the management of preeclampsia. There has also been considerable progress in unraveling the pathophysiology and identifying the cause of preeclampsia.

Animals↗
PubMed2001

Renal disorders in pregnancy.

This update discusses the mechanisms responsible for gestational augmentation of renal haemodynamics, the role of urinary tract infections in preterm labour and paediatric development, and the importance of post-delivery infection and its relationship to previous catheterization. Pregnancy in women with chronic renal disease, on dialysis or with a kidney transplant, is reviewed emphasizing the risks in those women who already have problems pre-pregnancy, the problems associated with medication used during pregnancy and the impact of pregnancy on long-term prognosis. New information about altered glomerular physiology in pre-eclampsia is assessed.

Chronic Disease↗
PubMed2000

Coexistent hemoconcentration and hypoosmolality during superovulation and in severe ovarian hyperstimulation syndrome: a volume homeostasis paradox.

OBJECTIVE: To investigate the concomitant time courses of the changes in osmolality and calculated blood volume during the genesis of ovarian hyperstimulation syndrome (OHSS). DESIGN: Prospective longitudinal study. SETTING: IVF-ET program in a university-based assisted reproductive technology center. PATIENT(S): Thirty women undergoing superovulation for IVF-ET. INTERVENTION(S): Blood and urine samples were obtained on seven occasions from the start of FSH stimulation until a pregnancy test. Five women with severe OHSS had daily blood and urine tests during hospitalization. MAIN OUTCOME MEASURE(S): Changes in serum and urine osmolality, serum electrolytes, albumin, hemoglobin, and hematocrit. RESULT(S): Blood volume in women with OHSS decreased significantly by 20% from days hCG +2 to +4, followed by a sustained increase of 30% above baseline from days hCG +8 to +12. There was no statistically significant change in blood volume in women without OHSS. There was a sharp decrease in serum osmolality in women without OHSS between days 0 and hCG +2, which recovered toward baseline from day 4 after hCG. In women with OHSS, there was an unexpected increase in osmolality of 6 mOsm/kg between days hCG -2 and 0, followed by a decrease of 8 mOsm/kg by day hCG +2; this was sustained until day hCG +12. Patients with OHSS demonstrated a concentration and dilution of their urine during the acute and recovery phases of the syndrome, respectively, despite persistence of the hypoosmolar state. CONCLUSION(S): Decreased osmolality in severe OHSS is maintained despite significant decreases and increases in blood volume, suggestive of fundamental alterations in osmoregulation.

Adult↗
PubMed1999

Clinical management of established pre-eclampsia.

This chapter summarizes the identification, assessment and management of women with established pre-eclampsia. Guidelines for out-patient management and in-patient treatment are given and are based on clinical experience and published reports. Drug treatment options are briefly reviewed and the timing of delivery is discussed. A comprehensive regimen for the intrapartum management of severe pre-eclampsia is provided founded on protocols used in the Royal Victoria Infirmary, Newcastle upon Tyne, over recent years. The chapter emphasizes the importance of medical history, clinical examination and investigations when arriving at what are often difficult clinical decisions. Controversial areas are highlighted with reference to recent published reports.

Anticonvulsants↗
PubMed1999

The effect of labour and maternal oxytocin infusion on fetal plasma oxytocin concentration.

It is not known whether human labour is associated with increased fetal oxytocin production or transfer of oxytocin across the placenta. Previous reports are contradictory, due in part, to the influence of maternal analgesia on fetal production. We determined plasma oxytocin concentration in the umbilical artery and vein of women after vaginal delivery and after caesarean section with general anaesthesia before or after the onset of labour. The results demonstrate that fetal production of oxytocin is not influenced by general anaesthesia, thus enabling comparison of labour and nonlabour samples at caesarean section. Labour was not associated with an increase in fetal oxytocin production. Oxytocin was also measured in the umbilical artery and vein during maternal oxytocin infusion to assess placental transfer. The results do not support transfer of oxytocin across the placenta in women.

Adjuvants, Anesthesia↗
PubMed1998

Subtracted, unique-sequence, in situ hybridization: experimental and diagnostic applications.

Nonrandom chromosomal aberrations, particularly in cancer, identify pathogenic biological pathways and, in some cases, have clinical relevance as diagnostic or prognostic markers. Fluorescence and colorimetric in situ hybridization methods facilitate identification of numerical and structural chromosome abnormalities. We report the development of robust, unique-sequence in situ hybridization probes that have several novel features: 1) they are constructed from multimegabase contigs of yeast artificial chromosome (YAC) clones; 2) they are in the form of adapter-ligated, short-fragment, DNA libraries that may be amplified by polymerase chain reaction; and 3) they have had repetitive sequences (eg, Alu and LINE elements) quantitatively removed by subtractive hybridization. These subtracted probes are labeled conveniently, and the fluorescence or colorimetric detection signals are extremely bright. Moreover, they constitute a stable resource that may be amplified through at least four rounds of polymerase chain reaction without diminishing signal intensity. We demonstrate applications of subtracted probes for the MYC and EWS oncogene regions, including 1) characterization of a novel EWS-region translocation in Ewing's sarcoma, 2) identification of chromosomal translocations in paraffin sections, and 3) identification of chromosomal translocations by conventional bright-field microscopy.

Burkitt Lymphoma↗
PubMed1998

Medical management of the pregnant transplant recipient.

Retrospective analyses of pregnancies in female renal transplant recipients including case reports, center reports, and questionnaire surveys have, for the most part, reached similar conclusions. In the presence of adequate, stable graft function, these high-risk pregnancies are generally well tolerated, but the majority of the liveborn outcomes are premature and many of the newborns are low birthweight. Obstetrical complications such as preeclampsia and cesarean section occur in a significant proportion of cases. With improvements in methods of data acquisition and computer technology, the aim for the future must be enhanced communication between transplant centers on a prospective basis, perhaps comparing cases with patient profiles derived from analyzed databases such as the National Transplantation Pregnancy Registry (NTPR). Continued efforts to identify prepregnancy risk factors as well as optimal antenatal management strategies will help to further improve pregnancy outcomes in this population. Discussed in this review are reports from the literature as well as current data from the NTPR focusing on the medical management of pregnancy in the renal transplant recipient.

Adult↗
PubMed1998

Primary cutaneous Ewing's sarcoma: immunophenotypic and molecular cytogenetic evaluation of five cases.

Cutaneous small blue cell tumors are relatively uncommon and include primary lesions of either adnexal or neuroendocrine differentiation, as well as metastatic disease. Extraosseous Ewing's sarcoma/malignant primitive neuroectodermal tumor (MPNET) rarely may occur as a primary, superficially based neoplasm in children and young adults. We describe a series of five cases of Ewing's sarcoma/malignant primitive neuroectodermal tumor occurring as a primary cutaneous malignancy supported diagnostically both by immunohistochemical stains and fluorescence in situ hybridization (FISH). All five cases occurred as a solitary dermal nodule and were located in the lower extremities (3 cases), the axilla (1 case), and the flank (1 case). Three of the cases were clinically polypoid. Four of the five patients were female, and age at presentation ranged form 8 to 50 years of age (median, 18 years). All five tumors consisted of nodular proliferations of monomorphous, small blue cells with round, vesicular nuclei, and scant to moderate cytoplasm that were uniformly immunoreactive for the CD99 cell surface glycoprotein in a characteristic membranous pattern. Fluorescence in situ hybridization analysis of paraffin-embedded tissue revealed that three of four tumors were positive for a chromosomal translocation involving the EWS locus at 22q12, seen in more than 90% of cases of Ewing's sarcoma/malignant primitive neuroectodermal tumor. One case was not analyzable. All five patients were treated using local excision, and two patients additionally received postoperative chemotherapy and radiotherapy. Clinical follow-up is available in three cases (median duration, 33 months) and to date none has shown evidence of either local recurrence or metastasis. Because similar cases reported in the literature have likewise had favorable clinical courses after excision, primary cutaneous Ewing's sarcoma/malignant primitive neuroectodermal tumor may represent a clinically favorable subset of this otherwise highly aggressive neoplasm.

Adolescent↗
PubMed1998

Drug safety issues in pregnancy following transplantation and immunosuppression: effects and outcomes.

Successful pregnancy outcomes are possible after solid organ transplantation. While there are risks to mother and fetus, there has not been an increased incidence of malformations noted in the newborn of the transplant recipient. It is essential that there is closely coordinated care that involves the transplant team and an obstetrician in order to obtain a favourable outcome. Current data from the literature, as well as from reports from the National Transplantation Pregnancy Registry (NTPR), support the concept that immunosuppression be maintained at appropriate levels during pregnancy. At present, most immunosuppressive maintenance regimens include combination therapy, usually cyclosporin or tacrolimus based. Most female transplant recipients will be receiving maintenance therapy prior to and during pregnancy. For some agents, including monoclonal antibodies and mycophenolate mofetil, there is either no animal reproductive information or there are concerns about reproductive safety. The optimal (lowest risk) transplant recipient can be defined by pre-conception criteria which include good transplant graft function, no evidence of rejection, minimum 1 to 2 years post-transplant and no or well controlled hypertension. For these women pregnancy generally proceeds without significant adverse effects on mother and child. It is of note that the epidemiological data available to date on azathioprine-based regimens are favourable in the setting of a category D agent (i.e. one that can cause fetal harm). Thus, there is still much to learn regarding potential toxicities of immunosuppressive agents. The effect of improved immunosuppressive regimens which use newer or more potent (and potentially more toxic) agents will require further study.

Adrenal Cortex Hormones↗
PubMed1997

Atrial natriuretic peptide in preeclampsia: metabolic clearance, sodium excretion and renal hemodynamics.

To further elucidate the role of atrial natriuretic peptide (ANP) in preeclampsia, its metabolic clearance (MCRANP) was determined concomitantly with its effects on sodium excretion (UNa), glomerular filtration rate (GFR), and effective renal plasma flow (ERPF). Ten untreated preeclamptic primigravidae (PET) were studied at 29-37 wk gestation and again 4 mo postpartum (PP). Basal plasma concentration of ANP was significantly increased in PET compared with PP (14.8 +/- 1.9 vs. 4.1 +/- 0.5 pmol/l, respectively; P < 0.0001). MCRANP in PET and PP was 5.0 +/- 0.8 and 4.9 +/- 0.5 l/min [not significant (NS)], respectively. In PET, infusion of ANP produced (basal vs. ANP) a natriuresis (UNa 0.14 +/- 0.02 vs. 0.28 +/- 0.04 mmol/min, P < 0.001) and an increase in GFR (97 +/- 7 vs. 106 +/- 8 ml/min, P < 0.05), with ERPF unchanged (609 +/- 24 vs. 634 +/- 29 ml/min, NS). In PP, ANP infusion also produced a natriuresis (UNa 0.20 +/- 0.02 vs. 0.25 +/- 0.02 mmol/min, P = 0.01), no significant change in GFR (109 +/- 7 vs. 102 +/- 4 ml/min), and a significant reduction in ERPF (514 +/- 22 vs. 409 +/- 18 ml/min, P < 0.0001). Analysis of variance demonstrated a greater natriuretic effect of ANP in PET compared with PP (P < 0.05), similarly a significant difference in the effect of ANP on ERPF (P < 0.01) and GFR (P < 0.05) was seen but not on filtration fraction (P = 0.35).

Adult↗