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Biomedical subjects

B Hamark

Publications and source records attributed to B Hamark.

9 recordsLinked to original sources
PubMed2006

Gestational and hormonal regulation of human placental lipoprotein lipase.

The fetal demand for FFA increases as gestation proceeds, and LPL represents one potential mechanism for increasing placental lipid transport. We examined LPL activity and protein expression in first trimester and term human placenta. The LPL activity was 3-fold higher in term (n = 7; P < 0.05) compared with first trimester (n = 6) placentas. The LPL expression appeared lower in microvillous membrane from first trimester (n = 2) compared with term (n = 2) placentas. We incubated isolated placental villous fragments with a variety of effectors [GW 1929, estradiol, insulin, cortisol, epinephrine, insulin-like growth factor-1 (IGF-1), and tumor necrosis factor-alpha] for 1, 3, and 24 h to investigate potential regulatory mechanisms. Decreased LPL activity was observed after 24 h of incubation with estradiol (1 micro g/ml), insulin, cortisol, and IGF-1 (n = 12; P < 0.05). We observed an increase in LPL activity after 3 h of incubation with estradiol (20 ng/ml) or hyperglycemic medium plus insulin (n = 7; P < 0.05). To conclude, we suggest that the gestational increase in placental LPL activity represents an important mechanism to enhance placental FFA transport in late pregnancy. Hormonal regulation of placental LPL activity by insulin, cortisol, IGF-1, and estradiol may be involved in gestational changes and in alterations in LPL activity in pregnancies complicated by altered fetal growth.

Adenosine Triphosphate↗
PubMed2004

Glucose transporter isoform 4 is expressed in the syncytiotrophoblast of first trimester human placenta.

BACKGROUND: Placental glucose transport mechanisms in early pregnancy are poorly understood. The aims of this study were to investigate the expression of glucose transporter (GLUT) isoforms 1, 3 and 4 in first trimester villous tissue, to assess the effects of insulin on glucose uptake and compare them with term. METHODS: The expression of GLUT isoforms was investigated using immunohistochemistry, Western blot and reverse transcription (RT)-PCR in trophoblast tissue from terminations at 6-13 weeks gestation and term. The effects of insulin (300 ng/ml, 1 h) on glucose uptake were studied in villous fragments. RESULTS: In the first trimester, GLUT1 and GLUT3 were present in the microvillous membrane and the cytotrophoblast, and GLUT4 in perinuclear membranes in the cytosol of the syncytiotrophoblast (ST). GLUT4 protein (48 kDa) and mRNA were identified in trophoblast homogenates. Whereas GLUT1 was expressed abundantly in term placenta, the expression of GLUT3 and 4 was markedly lower at term compared with first trimester. Insulin increased glucose uptake by 182% (n=6, P<0.05) in first trimester fragments, but not in term fragments. CONCLUSIONS: The insulin-regulatable GLUT4 is expressed in the cytosol of first trimester ST compatible with a role for GLUT4 in placental glucose transport in early pregnancy. The placental expression pattern of GLUT isoforms in early pregnancy is distinct from that later in pregnancy.

Blotting, Western↗
PubMed2003

Store-operated Ca2+ entry in first trimester and term human placenta.

We have examined whether store-operated Ca2+ entry, a common pathway for Ca2+ entry in non-excitable tissue, is apparent in the syncytiotrophoblast of both first trimester and term human placenta. Expression of transient receptor potential (TRPC) homologues, a family of channels thought to be involved in store-operated Ca2+ entry, was also studied at the mRNA and protein levels. [Ca2+]i in syncytiotrophoblast of first trimester and term placental villous fragments was measured by microfluorimetry using the Ca2+-sensitive dye fura-2. Store-operated Ca2+ entry was stimulated using 1 microM thapsigargin in Ca(2+)-free Tyrode buffer (no added Ca2+ + 1 mM EGTA) followed by superfusion with control (Ca2+-containing) buffer. In term fragments, this protocol resulted in a rapid increase in [Ca2+]i, which was inhibited in the presence of 150 microM GdCl3, 200 microM NiCl2, 200 microM CoCl2 or 30 microM SKF96365 but was unaffected by addition of 10 microM nifedipine. It was not possible to stimulate such a rise in [Ca2+]i in first trimester fragments. Messenger RNA encoding TRPC1, TRPC3, TRPC4, TRPC5 and TRPC6 was identified in both first trimester and term placentas. From Western blotting, TRPC3 and TRPC6 proteins were detected in term, but not in first trimester, placentas, while TRPC1 protein was not detected. By immunocytochemistry, TRPC3 and TRPC4 were localised to cytotrophoblast cells in first trimester placentas and to the syncytiotrophoblast in term placentas. TRPC6 staining was present in the syncytiotrophoblast of both first trimester and term placenta, but the intensity was much greater in the latter. We propose that store-operated Ca2+ entry may be an important route for Ca2+ entry into the syncytiotrophoblast of term, but not first trimester placentas, and that in human placenta TRPC channels may underlie this entry mechanism.

Adult↗
PubMed1995

The influence of social class on parity and psychological reactions in women coming for induced abortion.

OBJECTIVE: To test the hypothesis that the correlation between legal abortion and socio-economic conditions, known from the time when abortion was restricted, has current validity. To evaluate the effect of social class on network support and psychological reactions. DESIGN: Consecutive sampling and semistructured personal interviewing. SUBJECTS: 444 women living in the city of Gothenburg and applying for legal termination of pregnancy in the first trimester. SETTING: The department of gynaecology at a university hospital with primary care responsibility for legal abortions. RESULTS: The 667 health administration districts of Gothenburg were ranked into four groups according to the mean income. Women living in lower socio-economic districts were younger. Irrespective of age, previous experience of induced abortion was more common among them (p < 0.001). Unsatisfactory network response or support was common (37%), but equally shared between the social classes. Discontinuation of oral contraception during the previous six months was twice as common among teenagers (40.0%) as among other women (p < 0.001) but without social differences. Pitman's permutation test was used for statistical analyses. CONCLUSION: Socio-economic conditions have a strong and inverse correlation to previous experience of induced abortion. Psychological reactions and needs did not vary with class.

Abortion Applicants↗
PubMed1991

Postabortal endometritis in chlamydia-negative women--association with preoperative clinical signs of infection.

The relations between clinical signs of infection and postoperative endometritis were studied among 429 women with negative preoperative chlamydial and gonococcal cultures. Clue cells and a vaginal smear not dominated by rods and positive amine tests were more common among the 12 patients (2.8%) with endometritis. In the stepwise logistic regression procedure the presence of greater than 20% clue cells remained statistically significant and was associated with the highest relative risk, 5.6, with 95% confidence limits 1.82-17.2. This also implies clinical significance--women with clue cells constitute a group at risk of postabortal endometritis.

Abortion, Induced↗
PubMed1988

Herpes simplex virus infection of the human sensory neuron. An electron microscopy study.

Herpes simplex virus (HSV) type 1 was used to infect cultures of human embryonic dorsal root ganglion cells. Infected cultured were studied by electron microscopy. Viral nucleocapsids were observed to be internalized into neuronal cells bodies and neuritic extensions by fusion of the viral envelope and the plasma membrane. No signs of internalization by endocytosis were noted. Nucleocapsids were transported in neurites and were within 2 hrs postinfection found located near the microtubules and close to the nuclear pores in the perikaryon. A primary envelopment of nucleocapsids occurred at the inner lamina of the nuclear membrane and virions appeared between the two laminae. Presence of non-enveloped nucleocapsids outside the nuclear membrane and in close contact with the endoplasmic reticulum suggested that nucleocapsids could pass to the cytoplasmic side probably by de-envelopment at the outer nuclear membrane. A secondary envelopment occurred at the endoplasmic reticulum where the virions also became enclosed in transport vesicles. Enveloped virus appearing in the cytoplasm of neurons and neuritic extensions was always found only inside these transport vesicles. During their passage through the cytoplasm the virion-transport vesicle complexes were surrounded by smaller lysosome-like vesicles possibly derived from the Golgi apparatus. Fusion reactions between vesicles with virions and the smaller vesicles seemed to occur. We discuss if in this way the virion-transport vesicle complexes might be provided with glycosyl transferases and substrates necessary for maturation and completion of glycosylation of the viral envelope glycoproteins. The transport vesicles seemed essential for egress of virions from the infected cell by releasing virus when fusing with the plasma membrane.

Capsid↗
PubMed1976

Isolation of Chlamydia in acute salpingitis.

In 22 patients with acute salpingitis, verified by laparoscopy, samples for attempted isolation of bacteria, Mycoplasma and Chlamydia were drawn from aspirates and cervical smears. CF-antibodies to Chlamydia were measured to acute and convalescent phase sera. Anaerobic bacteria were isolated from tubal secretions in two patients and Mycoplasmas in one patient. In two patients Chlamydia were recovered from the Fallopian tube. The serological investigation indicated Chlamydia infection in 6 patients.

Acute Disease↗