Gudmundur Gunnarsson

Proton and deuterium NMR of hydrogen bonds: Relationship between isotope effects and the hydrogen bond potential

Abstract The difference in chemical shift between hydrogen bonded protons and deuterons has been examined both theoretically and experimentally. It is shown that valuable information about the hydrogen bond potential can be extracted from this isotope effect on chemical shifts.

Middle cerebral artery velocimetry as a predictor of hypoxemia in fetuses with increased resistance to blood flow in the umbilical artery

About half of all fetuses with increased resistance to blood flow, but with still detectable diastolic blood velocity in the umbilical artery (UA), show signs of imminent asphyxia during labour indicating a need for operative delivery. Fetal brain-sparing during hypoxia is characterized by an increase in diastolic and mean blood flow velocity in the middle cerebral artery (MCA). The aim of this study was to assess whether MCA blood velocity in pregnancies with increased resistance to blood flow in the feto-placental circulation could predict the development of fetal asphyxia during labour. Fifty pregnant women with signs of increased feto-placental vascular resistance between 31 and 42 weeks of gestation were studied serially by Doppler ultrasound and the last examination was correlated to perinatal outcome. The MCA pulsatility index (PI), cerebroplacental PI ratio and mean MCA blood velocity were calculated and correlated to fetal outcome. Fetal brain-sparing was defined as MCA PI < mean -2 S.D., cerebroplacental PI ratio < 1.08 and mean MCA blood velocity >mean + 2 S.D. No significant association was found between signs of fetal brain-sparing and the perinatal outcome. Among fetuses with signs of increased resistance to flow in the umbilical artery, velocimetry of the middle cerebral artery did not identify those that would not withstand the strain of labour.

Venous Doppler velocimetry in relationship to central venous pressure and heart rate during hypoxia in the ovine fetus

Abstract Objective: Characteristic changes in ductus venosus (DV) blood velocity and pulsations in the umbilical vein (UV) have been described during imminent fetal asphyxia. The aim of this study was to examine fetal venous blood velocity in relationship to pressure gradient across the DV during hypoxia in a fetal lamb preparation. Methods: In general anesthesia, a cesarean section was performed on seven pregnant ewes, the fetus was exteriorized and put into a heated waterbath with uninterrupted umbilical circulation. Pressure measurements in the UV and inferior vena cava (IVC) were performed with the catheter tips on both sides of the DV. Fetal hypoxemia was induced by giving the ewe 12 % oxygen in inhaling air. Pressure across the DV and Doppler velocimetry were repeatedly measured during hypoxemia. Blood velocity was recorded in the DV and UV by Doppler ultrasound. Results: Before hypoxia the median pressure gradient across the DV was in systole 1 mmHg and 0.31 mmHg in end-diastole and during hypoxemia 1.5 mmHg and zero, respectively. The pressure difference across the DV was constant during hypoxemia irrespective of the presence of umbilical venous pulsations or heart rate. IVC-pressure was greatly influenced by fetal heart rate (FHR). A small but linear fall in systolic IVC pressure was seen with increasing FHR. In end-diastole the IVC pressure changed in a parabolic fashion, with increasing pressure during brady- and tachycardia. Pulsations in the UV also showed a parabolic relationship to FHR and central venous pressure. DV end-systolic and end-diastolic blood velocity changed during hypoxemia in direct relationship to FHR and central venous pressure, but without direct relationship to fetal blood gases. Conclusion: The pressure gradient across the DV is constant during hypoxemia. Changes in central and umbilical venous pressure are directly related to FHR. Umbilical venous and DV blood velocity changed in direct relationship to FHR and central venous pressure.

Socioeconomic status and perinatal outcome according to residence area in the city of Malmö

Background. Maternal socioeconomic status is known to influence perinatal outcome. Antenatal care is free of charge in Sweden and all pregnant women are followed according to a standardized protocol of surveillance. The city of Malmö in southern Sweden is divided into 124 townships with great differences in socioeconomic standard. The aim of this study was to evaluate perinatal outcome according to the address of residence of the mothers within the city of Malmö.

Electrostatic effects on the migration rates of ions between charged micelles. Consequences for fluorescence quenching

Abstract The rate of exchange of countenons between micelles has been calculated from numerical solutions of the Poisson-Boltzmann equation for micelles in cells of spherical symmetry, and solutions of a steady-state diffusion problem for the ion in the resulting potential. The results indicate a rapid increase of the exchange rate with total amphiphilc concentration, as has been observed.

Assessment of Cesarean hysterotomy scar in non-pregnant women: reliability of transvaginal sonography with and without contrast enhancement

To determine intra‐ and interobserver reliability of evaluating the appearance and measurement of Cesarean hysterotomy scars using transvaginal ultrasound (TVS), with and without saline contrast sonohysterography (SCSH), in non‐pregnant women.

Cerebral Doppler blood flow velocimetry and central hemodynamics in the ovine fetus during hypoxemia-acidemia.

The purpose of this study was to assess the effects of hypocapnic hypoxia, acidemia and the combination of hypoxia/acidemia on blood flow velocity variables in the fetal cerebral circulation. Chronically instrumented fetal sheep were used and the ewes were induced to breathe a hypoxic gas mixture for about 90 min. This caused an initial period of hypoxemia followed by a period of mixed hypoxemia/acidemia. When the ewe was reoxygenated, the fetus experienced a period of normoxic acidemia. The fetal cerebral circulation was assessed by recording Doppler blood flow velocity waveform variables in a cerebral vessel and the umbilical artery, using standard ultrasound equipment. External carotid artery blood flow was maintained during hypoxic and hypoxic/acidotic periods despite a fall in cardiac output. In the cerebral vessel, mean maximum velocity (time-averaged maximum velocity), minimum diastolic velocity and maximum systolic velocity manifested increases during hypoxic and hypoxic-acidotic periods, but pulsatility index did not change due to the effect of reduced heart rate on pulsatility index. Umbilical artery pulsatility index increased in the hypoxic and hypoxic-acidotic periods, despite unchanged mean maximum velocity, minimum diastolic velocity and maximum systolic velocity. With acute hemodynamic changes, the measurement of pulsatility index can yield misleading results. For clinical and experimental research on the fetal cerebral circulation, more attention should be paid to the individual Doppler variables, especially to the mean maximum velocity, than to the pulsatility index alone. Changes in mean maximum velocity recorded from the cerebral artery seem to reflect changes in the cerebral arterial flow.

The Association of Ionic Surfactants to Micelles and Liquid Crystalline Phases: A Thermodynamic Model

A model for the association behaviour of ionic surfactants is presented, in which it is emphasized that the formation of micelles in a dilute aqueous solution is but a first step in a continuing association process leading to liquid crystalline phases and also to reversed micellar solutions. Using an expression for the free energy, which contains contributions due to the hydrophobic effect and the electrostatic free energy, chemical potentials for all the components are derived. In particular the electrostatic contributions are treated in detail using the Poisson-Boltzmann equation and the cell model. Spherical, cylindrical, and planar aggregates are considered. The calculated chemical potentials are compared with experiments relating to monomer and counterion activities, phase equilibria and CMC values. In all cases it is found that there is good agreement between theory and experiment. It is particularly gratifying that the phase boundaries (including two phase regions) are predicted with good accuracy.

Remote fetal medicine consultation using video streaming

Objective: To evaluate the use of videostreaming technique for live video telemedicine link for fetal ultrasonographic consultations. Methods: A link was established between two fetal ultrasound units in the Southern Swedish Health Care Region for consultations in cases of suspected fetal developmental abnormalities. Video compression standards MPEG1 and MPEG2 and videostreams with constant bandwidth of 1.5 Mbit/s (MPEG1) and 2 Mbit/s (MPEG2) were used. The transferred ultrasound images were discussed using regular telephone between the examiner and the expert. In cases of termination of pregnancy, the link was also used for telepathological transmission of macroscopic and microscopic images from the post mortem examination. Results: In a pilot study, the quality of ultrasound images from examination of fetuses in uncomplicated pregnancies was judged acceptable. Subsequently, the system was used for following consultations: 1. Twin pregnancy with an anencephalic fetus (24 wks); 2. Cleft-lip (29 wks); 3. Polycystic kidneys and oligohydramniosis (17 wks); 4. Hygroma and generalized hydrops with oligohydramniosis. In all four cases the quality of ultrasound images was considered excellent, fully sufficient for a reliable diagnosis and planning of the clinical management. In two cases (No. 3 and 4), the postmortem findings (polycystic kidneys with lung hypoplasia; bilateral multicystic hygroma with lymphoedema, aortic arch hypoplasia) were demonstrated by telemedicine to the clinicians at the central hospital. Conclusions: The low-cost videostreaming technique enables a fetal telemedicine service both on an immediate (on-line) and mediate (off-line transmission of video-recorded images) basis. This allows for a cost-effective access to a second opinion without a primary transfer of the patient to the regional center.

OP13.03: Transanal 4D/3D sonography combining inspection of the squeeze mechanism and integrity of the anal sphincter—a pilot study

Objectives: Overactive bladder (OAB) symptoms and objective assessment of a these symptoms is complex. A mean bladder wall thickness (BWT) of greater than 5mm is associated with detrusor overactivity but its application as a screening tool is not proved. There are no studies assess urinary symptoms and BWT. The aim of this study was to assess BWT and patient’s symptoms. Methods: One hundred and eighty two women participated. Women completed a HRQoL questionnaire and completed a 4 day bladder diary, and a visual analogue scale for urgency. Women were scanned transvaginally for bladder wall thickness with an empty bladder (< 50ml) at the trigone, dome, and anterior wall. The mean of these three measurements was calculated. Mean BWT and women’s symptoms, bladder diary data and urgency severity was assessed using a threshold of 5mm. Results: The mean age of our group of patients was 59 years. Eighty five women (47%) reported overactive bladder symptoms (OAB), 50/182 (28%) reported stress urinary incontinence, and 47/182 (26%) women reported mixed urinary incontinence. Of the women with OAB, 72/85 (85%) had a mean BWT of greater than 5mm. From bladder diary data, women with night time frequency of > once per night had a mean BWT of 5.3mm (95% CI 5.0–5.5) whereas women with night time frequency of one or less had a mean BWT of 4.3mm (95% CI 4.0–4.7). Women with a VAS urgency score of less than or equal to 2 had a mean BWT of 4.2mm (SD:0.5). Women with a VAS urgency score of > 2 had a mean BWT of 5.2mm (SD 0.77) (p <0.05, Mann Whitney U test). Conclusions: Mean BWT shows a strong association with womens’ OAB symptoms with 85% of the women in our study with OAB having an elevated mean BWT. Elevated mean BWT was associated with increased severity of urgency by VAS, and increased night time frequency. There was no association of mean BWT and daytime frequency. Mean BWT is closely related to both symptoms and diary data. It may be a useful tool in symptom assessment and an objective measure of bladder dysfunction.