Correlates of regular exercise during pregnancy: the Norwegian Mother and Child Cohort Study

The aims of this study were to describe the level of exercise during pregnancy and to assess factors associated with regular exercise. Using data from the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health, 34 508 pregnancies were included in the present study. Data were collected by self-completed questionnaires in gestational weeks 17 and 30, and analyzed by logistic regression analysis. The results are presented as adjusted odds ratios (aOR) with a 95% confidence interval. The proportion of women exercising regularly was 46.4% before pregnancy and decreased to 28.0 and 20.4% in weeks 17 and 30, respectively. Walking and bicycling were the most frequently reported activities before and during pregnancy. The prevalence of swimming tended to increase from prepregnancy to week 30. Exercising regularly prepregnancy was highly related to regular exercise in week 17, aOR=18.4 (17.1–19.7) and 30, aOR 4.3 (4.1–4.6). Low gestational weight gain was positively associated with regular exercise in week 30, aOR=1.2 (1.1–1.4), whereas being overweight before pregnancy was inversely associated with regular exercise in week 17, aOR=0.8 (0.7–0.8) and 30, aOR=0.7 (0.6–0.7). Also, women experiencing a multiple pregnancy, pelvic girdle pain, or nausea were less likely to exercise regularly.     

Arterial PCO2 and pH in man during 3 days' exposure to 2.8 kPa CO2 in the inspired gas

It has not been firmly established how respiration adapts to long-term CO2 exposure in man. We have therefore exposed five healthy human subjects to 2.8 kPa CO2 in the inspired gas for about 70 h in a chamber with controlled atmospheric conditions at ambient pressure PCO2 and pH were determined in arterial or arterialized venous blood drawn before, during and after the exposure. One subject was studied twice. We found that PaCO2 increased acutely and then increased further within the 5- to 24-h period of exposure to 2.8 kPa CO2. No consistent change was observed during the following 2 days. At the end of exposure the PaCO2 was 0.5 kPa above the pre-exposure level. When the breathing gas was switched back to room air, PaCO2 promptly returned to pre-exposure values. The secondary rise in PaCO2 within the first day would correspond to a decrease in alveolar ventilation of about 10% assuming constant production and elimination of CO2. Arterial pH remained slightly below the pre-exposure level during the entire exposure period. A slight renal compensation resulting in an increase in base excess of about 1 mmol l-1 may have occurred in the middle part of the exposure period. We conclude that a significant, but moderate, respiratory adaptation takes place during the first day of exposure to an increased inspired load of CO2.     

Further Studies on the State of Unresponsiveness Against Skin Homografts, Induced in Adult Mice of Certain Genotypes by a Previous Ovarian Homograft

The skin of strain A.BY donors is uniformly rejected in (A×C57BL) F₁ hybrid recipients. A.BY itself is a co-isogenic resistant (IR) subline of the A/Sn strain which contains H-2^b and segregates with regard to numerous, weaker loci (Linder and Klein, 1960). The action studied is thus directed against several weaker histocompatibility factors, all non-H-2.

In agreement with earlier findings, ovarian grafts from A.BY donors were found to abrogate the homograft reaction of adult (A×C57BL)F₁ hybrids against a subsequent skin graft from the same donor. The ovaries themselves also showed permanent survival and function. Abrogation of the homograft reaction to such an extent that subsequently homografted skin survived permanently was only found possible if the genetic gap between donor and recipient was so slight that skin survived for 29 days or more in untreated recipients. The state of unresponsiveness was not entirely specific and ovaries were found to be capable of inducing a state of tolerance not only against skin from the same donor but also against genetically somewhat different, although closely related A.BY donors as well.

The ability of ovarian grafts to withstand the homograft reaction was demonstrated in an experiment in which their degree of invulnerability was such as to enable them to overcome even the degree of sensitivity produced by a prior skin graft of the ovarian genotype.

The state of unresponsiveness could not be transferred passively with serum and was not influenced by splenectomy of the recipients.

Testicular grafts and submaxillary grafts were not capable of abrogating the homograft reaction in the same way as ovaries; on the contrary, they induced a second set reaction.

     

Lack of bubble formation in hypobarically decompressed cells

Suspensions of human erythrocytes or of unicellular microorganisms (Tetrahymena pyriformis, Euglena gracilis, Escherichia coli, and Microcyclus aquaticus) were equilibrated with nitrogen gas pressures up to 200 atm and rapidly decompressed to hypobaric pressures below the vapor point of water. The intracellular environments proved to be very tolerant to the gas supersaturations induced. None or only a few cells were damaged in each case, and bubbles were never observed intracellularly after decompression. In view of such extreme tolerances, it is doubtful that bubbles originate intracellularly during decompression of multicellular organisms, in which bubbles occur with far lower gas supersaturations, unless the tolerances are greatly affected by extensive mechanical deformations of the cells or by the presence of internalized particles with bubble-promoting properties.     

A chemical waveform synthesizer

Algorithms and methods were developed to synthesize complex chemical waveforms in open volumes by using a scanning-probe microfluidic platform. Time-dependent variations and oscillations of one or several chemical species around the scanning probe, such as formation of sine waves, damped oscillations, and generation of more complex patterns, are demonstrated. Furthermore, we show that intricate bursting and chaotic calcium oscillations found in biological microdomains can be reproduced and that a biological cell can be used as a probe to study receptor functionalities as a function of exposure to time-dependent variations of receptor activators and inhibitors. Thus, the method allows for studies of biologically important oscillatory reactions. More generally, the system allows for detailed studies of complex time-varying chemical and physical phenomena in solution or at solution/surface interfaces.     

Comparison between the Klemetti index and heel DXA BMD measurements in the diagnosis of reduced skeletal bone mineral density in the elderly

Osteopenia/osteoporosis affect many elderly people and might not be detected until symptoms of fractures occur. Early detection of osteopenia/osteoporosis is important and would allow preventive measures and treatment. Access to screening for osteopenia/osteoporosis is often limited, whereas panoramic radiography is commonly used in dentistry. The aim of this study was to determine the validity of the Klemetti index (KI), measured on panoramic radiographs, in the diagnosis of osteopenia/osteoporosis as defined by a bone mineral density (BMD) measurement below –1.5 standard deviations (SDs) of a community based sample. In total, 211 consecutive participants (102 men and 109 women) 60–96 years in the SNAC–Blekinge study (Swedish National Study on Ageing and Care) underwent bone densitometry [by dual-energy X-ray absorptiometry (DXA)] of both heels. A panoramic radiograph was taken of each participant, and mandibular cortex on a panoramic radiograph was classified as 0 or normal (even and sharp endosteal margin), 1, moderately eroded (evidence of lacunar resorption or endosteal cortical residues), or 2, severely eroded (unequivocal porosity). From logistic regression, the odds ratio of having a BMD measurement below –1.5 SD was 8.04 (95% CI 2.39 to 27.12, P<0.001) in the osteopenic (KI category 2), compared with the normal group (KI categories 0 and 1). Receiver operating characteristic (ROC) curve analysis was used to measure the validity of the KI indicating osteopenia (KI category 2) in predicting reduced BMD. This point provided a sensitivity of 50% and a specificity of 89%. Positive and negative predictive values were 21% and 97%, respectively. There were 87% correctly classified subjects. The area under the ROC curve was 0.64. The present study demonstrated that a negative finding (KI category <2) is highly predictive of the absence of osteopenia/osteoporosis as defined by the DXA measurements.     

To be and to have a critical friend in medical teaching

Background  In order to stimulate reflection and continuous professional development, a model of critical friends evaluating each other was introduced in medical education.
Objective  To investigate whether the critical friend concept can serve as a pragmatic model for evaluation of medical teachers and as a fruitful tool for enhancing self-knowledge and professional development among medical educators.
Methods  Three pairs of critical friends were formed, consisting of experienced medical teachers ( n  = 6) at the Karolinska Institutet. Each teacher was assigned to give 1 lecture and 1 seminar in his or her specific research or clinical field. The critical friend evaluated the performance in class, acting as an observer using a pre-formed protocol. The evaluation was communicated to the teacher during a 45-minute session within 48 hours after the teaching session. Each of the 6 teachers was criticised and gave criticism within the pair configurance. The outcome of the process was evaluated by an experimenter, not participating in the process, who performed a semistructured interview with each of the 6 teachers.
Results  Each teacher had a different way of reflecting on teaching after the project than before and made changes in his or her way of teaching. We also noted that being a critical friend may be even more effective than having one. The majority of the feedback provided was positive and valuable.
Conclusion  To be and to have a critical friend is worth the extra workload. Therefore, the critical friend concept should be made part of regular teaching practice .     

The ionic stoichiometry of the GLAST glutamate transporter in salamander retinal glia

Maintaining a low extracellular glutamate concentration in the central nervous system is important for terminating synaptic transmission and preventing excitotoxic cell death. The stoichiometry of the most abundant glutamate transporter, GLT-1, predicts that a very low glutamate concentration, ∼2 n m , should be reached in the absence of glutamate release, yet microdialysis measurements give a value of ∼1 μ m . If other glutamate transporters had a different stoichiometry, the predicted minimum glutamate concentration could be higher, for example if those transporters were driven by the cotransport of 2 Na⁺ (rather than of 3 Na⁺ as for GLT-1). Here we investigated the ionic stoichiometry of the glutamate transporter GLAST, which is the major glutamate transporter expressed in the retina and cerebellum, is expressed in other adult brain areas at a lower level than GLT-1, and is present throughout the brain early in development when expression of GLT-1 is low. Glutamate transport by GLAST was found to be driven, as for GLT-1, by the cotransport of 3 Na⁺ and 1 H⁺ and the counter-transport of 1 K⁺, suggesting that the minimum extracellular glutamate concentration should be similar during development and in the adult brain. A less powerful accumulation of glutamate by GLAST than by GLT-1 cannot be used to explain the high glutamate concentration measured by microdialysis.