Search PubMed⌕ Search

Biomedical subjects

J J Morrison

Publications and source records attributed to J J Morrison.

At least 37 records · Page 2Linked to original sources
PubMed1998

Crystallization and stabilization of MB-1, a de novo designed protein for optimized feeding technology.

Milk Bundle-1 is a de novo protein that was designed for application in agriculture. It has a high content of selected essential amino acids, and is intended to adopt an alpha-helical bundle fold. Crystallization experiments with MB-1 have been carried out on the ground and in reduced gravity on board Columbia orbiter during mission STS-80. Rather small crystals were obtained (< 0.05 mm) in both environments. Among other factors, the lack of stability of purified MB-1 has been detrimental to crystal growth. We report here on our progress with regard to optimizing crystal growth conditions, protein purification and protein stability. The first MB-1 mutant we present (MB-1-His) contains a poly-histidine tail, allowing the use of metal affinity chromatography for purification. MB-1-His has been found to keep its original mass for a month at room temperature, a spectacular improvement over MB-1. The other mutant (MB-1-Cys) was engineered to carry a cysteine residue on a solvent exposed face. The exposed cysteine binds readily to p-HMB, and allows for dimerization of MB-1-Cys. The dimer was found to be twice as stable as MB-1 during proteolytic degradation studies.

Amino Acid Sequence↗
PubMed1998

Activation of large-conductance potassium channels in pregnant human myometrium by pinacidil.

OBJECTIVE: The aim was to investigate the effects of the potassium-channel opener pinacidil on single uterine potassium channels and the contribution of the latter to pinacidil-induced myometrial relaxation. STUDY DESIGN: Myometrial strips and freshly dispersed uterine myocytes were prepared from the myometrial biopsy samples of women undergoing elective, nonlabor caesarean section at term gestation. RESULTS: In isometric tension experiments pinacidil potently relaxed pregnant nonlabor human myometrial strips, with an agonist concentration yielding the half maximal response of 0.4 +/- 0.1 micromol/L. This effect was antagonized by 500 nmol/L charybdotoxin. Application of 10 micromol/L glibenclamide also inhibited the pinacidil-induced relaxation. Coapplication of charybdotoxin (500 nmol/L) and glibenclamide (10 micromol/L) produced a biphasic curve, which was fitted to a two-site model with values for agonist concentration yielding the half maximal response of 0.6 +/- 0.2 micromol/L and 189.7 +/- 0.8 micromol/L. Large-conductance calcium-dependent potassium channel activity was dramatically increased after application of pinacidil (between 10 and 100 micromol/L) to both inside-out and outside-out patches. The activation required the presence of calcium ions at the intracellular aspect of the membrane. Charybdotoxin but not glibenclamide blocked pinacidil-induced unitary large-conductance calcium-dependent potassium channel activity. CONCLUSION: Pinacidil-mediated relaxation of human pregnant myometrial strips may be partially attributable to the opening of uterine large-conductance calcium-dependent potassium channels in addition to adenosine triphosphate potassium channel activation. Drugs with specific potassium channel-activating properties may have important clinical application as novel tocolytics in the treatment of preterm labor.

Calcium↗
PubMed1998

Trisomy 22: a cause of isolated fetal growth restriction.

The management of severe isolated fetal growth restriction at term involves consideration of the risk of associated aneuploidy. A case is described in which intrauterine growth restriction was detected at 37 weeks' gestation in a structurally normal fetus. The diagnosis of trisomy 22 was made after fetal blood sampling. This diagnosis has not been previously reported in a structurally normal fetus. This case highlights the dilemma that arises in the management of the small, structurally normal fetus in the late third trimester. The reasons for survival to term of some trisomy 22 fetuses are as yet unclear and are discussed.

Adult↗
PubMed1998

Prospective non-invasive monitoring of pregnancies complicated by red cell alloimmunization.

Our purpose was to evaluate the impact of non-invasive assessment of fetal anemia and anti-D antibody quantification on the timing and frequency of invasive procedures in pregnancies complicated by rhesus alloimmunization. Nineteen consecutive non-hydropic pregnancies referred to the fetal medicine center were assigned a prior risk category (none/mild, moderate or severe) and monitored by: (1) serial fetal measurements of umbilical vein maximal flow velocity (UVVmax), liver length and spleen perimeter measurements; and (2) serial anti-D antibody concentration. Invasive tests for fetal anemia (amniocentesis or fetal blood sampling) were deferred in the absence of abnormal ultrasound findings and/or rising antibody levels. In six cases serial non-invasive tests were normal with stable antibody levels, and no invasive tests were performed; four infants were mildly affected, one was unaffected and one required postnatal exchange transfusion. In the remaining 13 affected cases, amniocentesis was performed in nine cases for: elevated UVVmax alone (n = 3), elevated UVVmax and an increased antibody level (n = 2), or normal UVVmax with an increased antibody level (> 15 IU/ml) and severe prior risk category (n = 4). Six fetuses underwent fetal blood sampling (initial hematocrit 9-29%), and five of these had an elevated UVVmax. Liver length and spleen perimeter measurements were increased in only one anemic fetus (hematocrit 13%). Of 17 infants born alive, an elevated UVVmax prior to delivery was predictive of the need for exchange transfusion (six of seven cases with an elevated UVVmax vs. one of ten with a normal UVVmax; chi 2 = 5.73, p = 0.017 with Yates' correction). These preliminary data suggest that pregnancies with a mild or no history of fetal anemia may be monitored by a combination of serial antibody quantification and Doppler monitoring of UVVmax.

Adult↗
PubMed1998

Perinatal outcome and prognostic factors in prenatally diagnosed congenital diaphragmatic hernia.

OBJECTIVE: The purpose of this study was to assess perinatal outcome in cases of prenatally diagnosed congenital diaphragmatic hernia and identify the prognostic value of various prenatal factors. DESIGN: Retrospective review of fetal medicine, obstetric and histopathology records in all 34 cases of congenital diaphragmatic hernia identified prenatally between 1992 and 1996 at a tertiary referral fetal medicine unit. RESULTS: Overall survival was 18%. None of those with bilateral (0/1) or right-sided (0/5) congenital diaphragmatic hernia survived, whereas 21% (6/28) of those with left-sided hernias survived. Prenatal karyotyping was performed in 71% (n = 24) and five chromosomal abnormalities were identified. The pregnancy was terminated in 15 cases (44%). In the 19 continuing pregnancies, the survival rate was 32% (6/19). In those with an isolated congenital diaphragmatic hernia, the survival rate was 38% (5/13), and in those in which the hernia was isolated and left-sided, the survival rate was 56% (5/9). In ongoing pregnancies diagnosed after 24 weeks, the survival rate was 33% (2/6) compared with 31% (4/13) in pregnancies diagnosed at < or = 24 weeks. Of those infants who had surgical repair, six out of seven (86%) survived. CONCLUSIONS: These data clearly demonstrate an improved prognosis in fetuses with an isolated left-sided congenital diaphragmatic hernia.

Adolescent↗
PubMed1998

Intra-amniotic inflammation in human gastroschisis: possible aetiology of postnatal bowel dysfunction.

OBJECTIVE: To assess amniotic fluid for evidence of an inflammatory exudate in association with fetal gastroschisis. SETTING: University College Hospital, London and Institute of Child Health, London. SAMPLE: Samples of amniotic fluid in the third trimester from pregnant women with a diagnosis of fetal gastroschisis (n = 10) and from a control group (n = 10) with a normal fetus. METHODS: Cytological analysis of the fluid was performed. Flow cytometry was performed on the amniotic fluid using antibodies for the myeloid cell antigen CD15, the leucocyte beta integrin CD11b/CD18 and CD3, CD19, CD56 and CD25. Tumour necrosis factor alpha and interleukin-8 levels were assayed in the amniotic fluid. RESULTS: An acute inflammatory exudate, composed predominantly of neutrophil polymorphs and mononuclear cells, was found in the amniotic fluid in fetal gastroschisis but not in control cases. When amniotic fluid samples from cases of fetal gastroschisis were stained with CD15, analysis by flow cytometry showed a clear positive population. This CD15 population showed markedly elevated levels of CD11b. No distinct population of CD15 positive cells was seen in amniotic fluid samples examined from the control group. No staining was seen with antibodies to CD3, CD19, CD56 or CD25 in amniotic fluid obtained from either group. There was no significant difference between tumour necrosis factor alpha levels measured in the amniotic fluid of cases of fetal gastroschisis (median 102 pg/mL; range 20-340) and those of the control group (140 pg/mL; range 20-548) (P = 0.1). The levels of interleukin-8 were markedly elevated in the amniotic fluid of cases of fetal gastroschisis (median 6320 pg/mL; range 4732-13,800) compared with the control group (median 1738 pg/mL; range 623 2861;) (P < 0.01). CONCLUSION: Human fetal gastroschisis is associated with an inflammatory exudate in the amniotic fluid which may have implications for postnatal bowel function.

Adult↗
PubMed1997

Ca2+ dependence and pharmacology of large-conductance K+ channels in nonlabor and labor human uterine myocytes.

Two populations, Ca(2+)-dependent (BKCa) and Ca(2+)-independent K+ (BK) channels of large conductance were identified in inside-out patches of nonlabor and labor freshly dispersed human pregnant myometrial cells, respectively. Cell-attached recordings from nonlabor myometrial cells frequently displayed BKCa channel openings characterized by a relatively low open-state probability, whereas similar recordings from labor tissue displayed either no channel openings or consistently high levels of channel activity that often exhibited clear, oscillatory activity. In inside-out patch recordings, Ba2+ (2-10 mM), 4-aminopyridine (0.1-1 mM), and Shaker B inactivating peptide ("ball peptide") blocked the BKCa channel but were much less effective on BK channels. Application of tetraethylammonium to inside-out membrane patches reduced unitary current amplitude of BKCa and BK channels, with dissociation constants of 46 mM and 53 microM, respectively. Tetraethylammonium applied to outside-out patches decreased the unitary conductance of BKCa and BK channels, with dissociation constants of 423 and 395 microM, respectively. These results demonstrate that the properties of human myometrial large-conductance K+ channels in myocytes isolated from laboring patients are significantly different from those isolated from nonlaboring patients.

4-Aminopyridine↗
PubMed1996

Pre-caesarean section haemoglobin: a worthless investigation.

Haemoglobin concentration is measured routinely before caesarean section in many obstetric units. It is also measured early in the third trimester in order to screen for anaemia. We investigated the hypothesis that when the haemoglobin concentration was normal in the early third trimester, a repeat measurement immediately before surgery at term provided no useful additional information. A total of 106 cases were studied of elective (n = 45) and emergency (n = 61) caesarean sections. In the majority of elective (28 of 45) and emergency (49 of 61) patients, the haemoglobin concentration rose by term. In a minority of elective (14 of 45) and emergency (12 of 61) patients, the haemoglobin concentration fell. The largest fall was by 1.3 g/dl and the lowest term value was 10.1 g/dl. In three elective patients, the concentration did not change. Peri-operative management at term may therefore be guided by the haemoglobin concentration measured early in the third trimester. There appears to be no clinically significant change in haemoglobin during this time and there are physiological changes in the circulation that explain this effect. Discontinuation of routine pre-operative haemoglobin concentration measurement could lead to a significant financial saving.

Journal Article↗
PubMed1996

Activation of protein kinase C is required for oxytocin-induced contractility in human pregnant myometrium.

Intracellular mediators regulating the initiation of parturition are not fully understood. This study was designed to determine the possible mechanism of oxytocin-induced uterine contractility during labour. In-vitro isometric contraction studies were performed with longitudinal strips of human pregnant myometrium in the presence and absence of the protein kinase C inhibitors, staurosporine and RO 31-8220, and the tyrosine kinase inhibitor, genistein. Phospholipase D activity was measured by employing the transphosphatidylation reaction. Staurosporine significantly reduced oxytocin-stimulated contractile activity with mean activity reduced by > 50% following the addition of 10(-6) M staurosporine (P < 0.01), while addition of 10(-5) M resulted in a measured mean contractile activity of approximately 10% of the control (P < 0.001, n = 5). Similarly, uterine activity was minimal with oxytocin application following incubation with RO 31-8220, mean contractile activity being reduced by approximately 40% by the addition of 10(-7) M RO 31-8220 (P < 0.05) and by approximately 87% by the addition of either 10(-6) or 10(-5) M (P < 0.01, n = 3). Conversely, addition of genistein (10(-7) and 10(-6) M) had little effect on oxytocin-induced contractions, although at a higher concentration (10(-5) M) a significant reduction in oxytocin-induced contractile activity was observed (P < 0.01). Oxytocin evoked phospholipase D activation in a concentration- and time-dependent manner in cultured human pregnant myometrial cells (n = 4). These results indicate that activation of protein kinase C and tyrosine kinase are involved in the regulation of oxytocin-mediated myometrial contractile activity and that a coupled phospholipase D/phosphatidate phosphohydrolase pathway may play a role in the sustained stimulation of myometrial activity during labour.

Adult↗
PubMed1996

Messenger RNA encoding thiol protein disulphide isomerase in amnion, chorion and placenta in human term and preterm labour.

OBJECTIVE: To investigate levels of messenger RNA (mRNA) encoding thiol protein disulphide isomerase, in human amnion, chorion and placenta during pregnancy and in relation to term and preterm labour. DESIGN: Amnion, chorion and placenta from 33 women delivered between 24 and 41 weeks of gestation were used in the study. SETTING: Reproductive Molecular Research Group, Department of Obstetrics and Gynaecology, University of Cambridge Clinical School, Rosie Maternity Hospital, Cambridge. RESULTS: Women who were delivered spontaneously before 30 weeks of gestation had higher levels of mRNA encoding thiol protein disulphide isomerase in placenta and chorion than those who were delivered spontaneously after this time (placenta (P < 0.01, chorion P < 0.01) and compared with those who were delivered by elective caesarean section before 30 weeks of gestation (placenta (P < 0.01, chorion P < 0.05). In the group in whom spontaneous labour occurred, at all gestations studied, there were increased levels of mRNA encoding thiol protein disulphide isomerase in the placenta (P < 0.001) and chorion (P < 0.001) compared with the amnion. CONCLUSION: Changes in the steady state level of mRNA encoding thiol protein disulphide isomerase may play a role in the onset of preterm labour before 30 weeks of gestation.

Adolescent↗
PubMed1995

Neonatal respiratory morbidity and mode of delivery at term: influence of timing of elective caesarean section.

OBJECTIVE: To establish whether the timing of delivery between 37 and 42 weeks gestation influences neonatal respiratory outcome and thus provide information which can be used to aid planning of elective delivery at term. DESIGN: All cases of respiratory distress syndrome or transient tachypnoea at term requiring admission to the neonatal intensive care unit were recorded prospectively for nine years. SETTING: Rosie Maternity Hospital, Cambridge. SUBJECTS: During this time 33,289 deliveries occurred at or after 37 weeks of gestation. MAIN OUTCOME MEASURES: This information enabled calculation of the relative risk of respiratory morbidity for respiratory distress syndrome or transient tachypnoea in relation to mode of delivery and onset of parturition for each week of gestation at term. RESULTS: The incidence of respiratory distress syndrome at term was 2.2/1000 deliveries (95% CI; 1.7-2.7). The incidence of transient tachypnoea was 5.7/1000 deliveries (95% CI; 4.9-6.5). The incidence of respiratory morbidity was significantly higher for the group delivered by caesarean section before the onset of labour (35.5/1000) compared with caesarean section during labour (12.2/1000) (odds ratio, 2.9; 95% CI 1.9-4.4; P < 0.001), and compared with vaginal delivery (5.3/1000) (odds ratio, 6.8; 95% CI 5.2-8.9; P < 0.001). The relative risk of neonatal respiratory morbidity for delivery by caesarean section before the onset of labour during the week 37+0 to 37+6 compared with the week 38+0 to 38+6 was 1.74 (95% CI 1.1-2.8; P < 0.02) and during the week 38+0 to 38+6 compared with the week 39+0 to 39+6 was 2.4 (95% CI 1.2-4.8; P < 0.02). CONCLUSIONS: A significant reduction in neonatal respiratory morbidity would be obtained if elective caesarean section was performed in the week 39+0 to 39+6 of pregnancy.

Cesarean Section↗
PubMed1995

Ultrasonographic growth measurements in triplet pregnancies.

The incidence of triplet pregnancies is increasing due to the widespread use of ovulation induction agents and assisted conception treatments. The aim of this study was to acertain the normal ultrasonographic measurements for fetal growth parameters in triplet pregnancies. The ultrasonographic measurements of all triplet pregnancies managed in two major hospital centres were reviewed retrospectively and those in which there was less than 25% discordance in birth weight were included in the study. Triplet 50th centile for fetal biparietal diameter, whilst falling through the normal singleton centile range from 27 weeks gestation, did not fall below the 10th centile value of singletons. Triplet 50th centile for head circumference was equivalent to the singleton 10th centile from 23 weeks gestation. Triplet 50th centile for abdominal curcumference was persistently below that of the singleton 50th centile, falling below the singleton 10th centile from 29 weeks gestation. Normal growth rate of triplet gestations in the third trimester of pregnancy varies from that of singletons. An awareness of this altered growth rate is necessary to avoid the inappropriate diagnosis of asymmetrical triplet fetal growth retardation. We suggest that the growth curves presented here may be used to monitor triplet fetal growth.

Birth Weight↗
PubMed1995

ETA and ETB endothelin receptors in human myometrium characterized by the subtype selective ligands BQ123, BQ3020, FR139317 and PD151242.

ETA selective (BQ123, FR139317, PD151242) and ETB selective (BQ3020) ligands were used to define the binding characteristics and contractile function of endothelin receptor subtypes in human myometrium. In saturation binding assays with 10 microns-thick tissue sections [125I]endothelin-1 (ET-1) bound with a single affinity to receptors in the myometrium (Kd, 1.19 +/- 0.17 nM) and adjacent endometrium (Kd, 1.39 +/- 0.51 nM). Competition binding assays in myometrium revealed a heterogeneous population of receptors with BQ123 (Kd ETA, 1.43 +/- 0.33 nM; Kd ETB, 39.91 +/- 9.06 microM), FR139317 (Kd ETA, 2.54 +/- 0.87 nM; Kd ETB, 89.79 +/- 24.34 microM) and BQ3020 (Kd ETA, 4.57 +/- 0.58 microM; Kd ETB, 90.07 +/- 19.53 nM). The presence of these receptors in myometrium was confirmed by saturation assays with the new ETA selective ligand [125I]PD151242 (Kd, 0.93 +/- 0.08 nM; Bmax 138.7 +/- 1.0 fmol/mg protein) and the ETB selective [125I]BQ3020 (Kd, 0.62 +/- 0.07; Bmax 44.5 +/- 1.1 fmol/mg protein). Reverse-transcriptase PCR assays detected mRNA encoding both receptor subtypes in myometrium. Autoradiography with radiolabelled PD151242 and BQ3020 demonstrated that ETA receptors were the predominant subtype in the myometrium and identified a population of ETB receptors in the endometrium. In tissue bath experiments, an ET-1-induced increase in contractility of myometrial strips was antagonized by 10 microM FR139317 but not by BQ123 at the same concentration. The ETB agonist BQ3020, which is a potent agonist in animal tissue, did not increase contractility when tested at concentrations up to 2 microM.

Azepines↗