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Biomedical subjects

J Huber

Publications and source records attributed to J Huber.

At least 55 records · Page 3Linked to original sources
PubMed2001

Plasma insulin levels are increased by sertraline in rats under oral glucose overload.

Recognition and control of depression symptoms are important to increase patient compliance with treatment and to improve the quality of life of diabetic patients. Clinical studies indicate that selective serotonin reuptake inhibitors (SSRI) are better antidepressants for diabetic patients than other drugs. However, preclinical trials have demonstrated that not all SSRI reduce plasma glucose levels. In fact, fluoxetine increases and sertraline decreases glycemia in diabetic and non-diabetic rats. In the present study we evaluated plasma insulin levels during fasting and after glucose overload after treatment with sertraline. Adult male Wistar rats were fasted and treated with saline or 30 mg/kg sertraline and submitted or not to glucose overload (N = 10). Blood was collected and plasma insulin was measured. The mean insulin levels were: fasting group: 25.9 +/- 3.86, sertraline + fasting group: 31.10 +/- 2.48, overload group: 34.1 +/- 3.40, and overload + sertraline group: 43.73 +/- 5.14 microU/ml. Insulinemia was significantly increased in the overload + sertraline group. There were no differences between the other groups. No difference in glucose/insulin ratios could be detected between groups. The overload + sertraline group was the only one in which a significant number of individuals exceeded the upper confidence limit of insulin levels. This study demonstrates that sertraline increases glucose-stimulated insulin secretion without any change in peripheral insulin sensitivity.

Administration, Oral↗
PubMed2000

[Phytoestrogens and SERMS, alternatives to classical hormone therapy?].

Isoprene is the main component of steroid hormones. It is found in many plants and herbal compounds, e.g. the isoflavonoids are therefore slightly estrogenic. Since they are bound to the estradiol receptors, more active estrogens cannot induce a signal transduction. Hence phytoestrogens may be protective on breast tissue and other hormone dependent organs.

Aged↗
PubMed2000

Efficacy and tolerability of a monophasic oral contraceptive containing ethinylestradiol and drospirenone.

OBJECTIVE: To assess the contraceptive reliability, cycle control and tolerability of a new monophasic oral contraceptive containing 30 g ethinylestradiol plus 3 mg drospirenone (Yasmin, Schering AG, Berlin, Germany), it was compared with an established oral contraceptive containing 30 g ethinylestradiol plus 150 g desogestrel (Marvelon, NV Organon, Oss, The Netherlands). METHODS: A randomized, open-label, 13-cycle study was performed at 80 European centers. Contraceptive reliability, cycle control, blood pressure, body weight, the incidence of adverse events and skin condition were assessed during 13 cycles of oral contraceptive use, and at follow-up. Subjects recorded body weight on three consecutive days pretreatment and weekly thereafter. RESULTS: Of 2069 women who started the study and received the trial preparations in a ratio of 4:1 (ethinylestradiol/drospirenone, n = 1657; ethinylestradiol/desogestrel, n = 412), 1615 completed the 13 cycles plus follow-up, providing data for over 23,000 evaluable cycles. Eleven pregnancies occurred during treatment, only one of which (in the ethinylestradiol/drospirenone group) could not be ascribed to user failure or interaction with other factors. Both preparations provided effective contraception and cycle control. Pre-existing acne and seborrhea were improved and blood pressure was essentially unchanged. The two treatments differed in their effect on body weight, the difference being statistically significant. In the ethinylestradiol/drospirenone group, there was a distinct decrease over the whole treatment phase, while a subtle and less distinct decrease was documented in the ethinylestradiol/desogestrel group. CONCLUSIONS: The combination of 30 g ethinylestradiol/3 mg drospirenone provides effective oral contraception, excellent cycle control, good tolerability and a level of weight loss that may have a significant beneficial effect on compliance in women with a tendency to weight gain due to water retention.

Adolescent↗
PubMed2000

Behavioral responses to repeated cocaine exposure in mice selectively bred for differential sensitivity to pentobarbital.

Mice from the 20th generation of three lines divergently selected for response to pentobarbital-induced sedation times [long-sedation time (LST), short sedation time (SST), and randomly bred control (RBC)] were used to study cocaine-induced behavioral sensitization. These lines showed variable degrees of locomotor activities in response to cocaine. At a low cocaine dose and long withdrawal period (10 mg/kg, twice a day for 5 days followed by a 14-day withdrawal), the LST mice showed tolerance development. In response to cocaine, the locomotor activities of the SST were not significantly different from the RBC group. At a higher dose and a shorter withdrawal period (20 mg/kg, daily for 7 days followed by a 3-day withdrawal), the SST mice showed behavioral sensitization similar to the RBC mice, but the LST mice did not develop sensitization. The different responses in locomotor activity induced by cocaine suggest that genetic factors may play a role in determining the magnitude of response to this drug. Dopamine (DA) levels did not differ significantly in either striatum (STR) or nucleus accumbens (NAC) for the cocaine-treated animals to their corresponding saline-treated controls. The affinity (Kd) of D2 in the NAC decreased significantly, without changes in density (Bmax), in the cocaine-treated SST and RBC mice. On the other hand, the density of D2 binding sites in the SST and the RBC mice in the STR was significantly increased in cocaine-treated groups without change in Kd. The LST mice did not show any changes in the Kd and Bmax in either the STR or the NAC. Taken together, these findings suggest that the changes in the Kd of D2 in the NAC and the Bmax of D2 in the STR may contribute to the differences in locomotor responses to cocaine exposure in these mouse lines.

Analysis of Variance↗
PubMed2000

Development of an instrument to investigate parents' perceptions of research with newborn babies.

Neonatal intensive care nurses are often involved in research protocols as investigators, research assistants or staff nurses implementing the protocol and providing support and explanations to families. It is important, therefore, that nurses have information about parents' understanding of and attitudes towards the research process. The purpose of this study was to begin an exploration of parents' perceptions about research with newborn babies through the development and validation of a survey instrument. The questionnaire included: demographic questions; scaled items about research with newborn babies; scenarios describing research studies that varied in degree of risk and benefit to the newborn baby; questions about parents' willingness to enrol their newborn baby in the studies described; and questions regarding circumstances under which consent should be sought. Content and face validity were established by an expert panel and a pilot test conducted with a small group of health care professionals and lay persons. A convenience sample of 231 parents of newborn babies completed the final version of the questionnaire. Factor analysis revealed seven factors corresponding to issues identified in the literature, providing evidence of construct validity. Parents appeared to have no difficulty in completing the instrument and all questions were answered by the majority of participants. It was concluded that the questionnaire had adequate psychometric properties and that a mixed method approach can be fruitful in exploring sensitive issues.

Adult↗
PubMed2000

Hysterectomy is associated with postmenopausal body composition characteristics.

The impact of hysterectomy without oophorectomy and with no malignant purpose on body composition and postmenopausal weight gain was tested in 184 Viennese females aged between 47 and 57 years (mean 52.9). Hysterectomized women were significantly heavier than those who experienced a spontaneous menopause (controls). The amount of fat tissue, especially in the abdominal region, was significantly higher in hysterectomized women. Furthermore, they were reported to have experienced a significantly higher weight gain since menopause (9.1 versus 6.0 kg). No significant differences in bone mass were found. Psychological stress factors and hormonal changes following hysterectomy are discussed as possible causes of these differences.

Absorptiometry, Photon↗
PubMed1999

Postmenopausal weight status, body composition and body fat distribution in relation to parameters of menstrual and reproductive history.

OBJECTIVES: In the present study the association between menstrual and reproductive history patterns and weight status, fat distribution and body composition during postmenopause was tested. METHODS: In 106 healthy postmenopausal women ranging in age from 48 to 58 years (x = 53.7 year) the weight status was classified according to the recommendations of the WHO. Additionally body composition was estimated by dual energy X-ray absorptiometry and fat distribution was calculated using the fat distribution index. Weight status, body composition and fat distribution were correlated with self-reported parameters of menstrual and reproductive history (age at menarche, average cycle length, number of births, age at first and last birth, average pregnancy weight gain, age at menopause). RESULTS: It was shown that number of births, age at first birth and pregnancy weight gain were related significantly to the postmenopausal weight status, body composition and fat distribution. CONCLUSION: An early first birth a low number of births and a high weight gain during pregnancies can be assumed as risk factors for overweight, a higher amount of adipose tissue, android fat patterning and therefore for the development of the metabolic syndrome during postmenopause. In contrast no adverse effect of menstrual and reproductive parameters on postmenopausal bone mass was found.

Adipose Tissue↗
PubMed1999

Antivascular endothelial growth factor receptor (fetal liver kinase 1) monoclonal antibody inhibits tumor angiogenesis and growth of several mouse and human tumors.

Tumor angiogenesis is mediated by tumor-secreted angiogenic growth factors that interact with their surface receptors expressed on endothelial cells. Vascular endothelial growth factor (VEGF) and its receptor [fetal liver kinase 1 (Flk-1)/kinase insert domain-containing receptor] play an important role in vascular permeability and tumor angiogenesis. Previously, we reported on the development of anti-Flk-1 and antikinase insert domain-containing receptor monoclonal antibodies (mAbs) that potently inhibit VEGF binding and receptor signaling. Here, we report the effect of anti-Flk-1 mAb (DC101) on angiogenesis and tumor growth. Angiogenesis in vivo was examined using a growth factor supplemented (basic fibroblast growth factor + VEGF) Matrigel plug and an alginate-encapsulated tumor cell (Lewis lung) assay in C57BL/6 mice. Systemic administration of DC101 every 3 days markedly reduced neovascularization of Matrigel plugs and tumor-containing alginate beads in a dose-dependent fashion. Histological analysis of Matrigel plugs showed reduced numbers of endothelial cells and vessel structures. Several mouse tumors and human tumor xenografts in athymic mice were used to examine the effect of anti-Flk-1 mAb treatment on tumor angiogenesis and growth. Anti-Flk-1 mAb treatment significantly suppressed the growth of primary murine Lewis lung, 4T1 mammary, and B16 melanoma tumors and growth of Lewis lung metastases. DC101 also completely inhibited the growth of established epidermoid, glioblastoma, pancreatic, and renal human tumor xenografts. Histological examination of anti-Flk-1 mAb-treated tumors showed evidence of decreased microvessel density, tumor cell apoptosis, decreased tumor cell proliferation, and extensive tumor necrosis. These findings support the conclusion that anti-Flk-1 mAb treatment inhibits tumor growth by suppression of tumor-induced neovascularization and demonstrate the potential for therapeutic application of anti-VEGF receptor antibody in the treatment of angiogenesis-dependent tumors.

Animals↗
PubMed1999

[Unobserved death of an infant: cot death?].

Three children, two girls aged 8 and 12 months and one boy aged 7 weeks, were found dead unexpectedly. Autopsy revealed pneumonia in two children, following which the diagnosis of 'natural, explained death' was made; one child showed no abnormalities and the diagnosis read 'natural, unexplained death' (cot death). Autopsy may currently only be performed with parental permission or, in case of doubt about unnatural cause of death, by order of the public prosecutor. The authors propose routine performance of a protocolled autopsy by GP, pediatrician, pathologist and medical examiner in order to avoid subsequent and possibly incorrect doubt about the cause of death.

Autopsy↗
PubMed1999

CRM1-mediated recycling of snurportin 1 to the cytoplasm.

Importin beta is a major mediator of import into the cell nucleus. Importin beta binds cargo molecules either directly or via two types of adapter molecules, importin alpha, for import of proteins with a classical nuclear localization signal (NLS), or snurportin 1, for import of m3G-capped U snRNPs. Both adapters have an NH2-terminal importin beta-binding domain for binding to, and import by, importin beta, and both need to be returned to the cytoplasm after having delivered their cargoes to the nucleus. We have shown previously that CAS mediates export of importin alpha. Here we show that snurportin 1 is exported by CRM1, the receptor for leucine-rich nuclear export signals (NESs). However, the interaction of CRM1 with snurportin 1 differs from that with previously characterized NESs. First, CRM1 binds snurportin 1 50-fold stronger than the Rev protein and 5,000-fold stronger than the minimum Rev activation domain. Second, snurportin 1 interacts with CRM1 not through a short peptide but rather via a large domain that allows regulation of affinity. Strikingly, snurportin 1 has a low affinity for CRM1 when bound to its m3G-capped import substrate, and a high affinity when substrate-free. This mechanism appears crucial for productive import cycles as it can ensure that CRM1 only exports snurportin 1 that has already released its import substrate in the nucleus.

Animals↗
PubMed1999

Synthesis and properties of 2-(naphthosultamyl)methyl-carbapenems with potent anti-MRSA activity: discovery of L-786,392.

A series of 1beta-methyl-2-(naphthosultamyl)methyl-carbapenems bearing dicationic groups on the naphthosultamyl moiety was prepared and evaluated for activity against resistant gram-positive bacteria. Based on a combination of excellent in vitro antibacterial activity, acceptable mouse acute toxicity, and a desirable fragmentation pattern on beta-lactam ring opening, the analog 2g (L-786,392) was selected for extended evaluation.

Animals↗
PubMed1999

Reduced immunotoxicity and preservation of antibacterial activity in a releasable side-chain carbapenem antibiotic.

A carbapenem antibiotic, L-786,392, was designed so that the side chain that provides high-affinity binding to the penicillin-binding proteins responsible for bacterial resistance was also the structural basis for ameliorating immunopathology. Expulsion of the side chain upon opening of the beta-lactam ring retained antibacterial activity while safely expelling the immunodominant epitope. L-786,392 was well tolerated in animal safety studies and had significant in vitro and in vivo activities against methicillin- and vancomycin-resistant Staphylococci and vancomycin-resistant Enterococci.

Animals↗
PubMed1999

An unusual chemical reactivity of Sm site adenosines strongly correlates with proper assembly of core U snRNP particles.

The small nuclear ribonucleoprotein particles (snRNP) U1, U2, U4, and U5 contain a common set of eight Sm proteins that bind to the conserved single-stranded 5'-PuAU3-6GPu-3' (Sm binding site) region of their constituent U snRNA (small nuclear RNA), forming the Sm core RNP. Using native and in vitro reconstituted U1 snRNPs, accessibility of the RNA within the Sm core RNP to chemical structure probes was analyzed. Hydroxyl radical footprinting of in vitro reconstituted U1 snRNP demonstrated that riboses within a large continuous RNA region, including the Sm binding site, were protected. This protection was dependent on the binding of the Sm proteins. In contrast with the riboses, the phosphate groups within the Sm core site were accessible to modifying reagents. The invariant adenosine residue at the 5' end, as well as an adenosine two nucleotides downstream of the Sm binding site, showed an unexpected reactivity with dimethyl sulfate. This novel reactivity could be attributed to N7-methylation of the adenosine and was not observed in naked RNA, indicating that it is an intrinsic property of the RNA- protein interactions within the Sm core RNP. Further, this reactivity was observed concomitantly with formation of the Sm subcore intermediate during Sm core RNP assembly. As the Sm subcore can be viewed as the commitment complex in this assembly pathway, these results suggest that the peculiar reactivity of the Sm site adenosine bases may be diagnostic for proper assembly of the Sm core RNP. Consistent with this idea, a strong correlation was found between the unusual N7-A methylation sensitivity of the Sm core RNP and its ability to be imported into the nucleus of Xenopus laevis oocytes.

Adenosine↗
PubMed1999

KDR/Flk-1 is a major regulator of vascular endothelial growth factor-induced tumor development and angiogenesis in murine hepatocellular carcinoma cells.

Vascular endothelial growth factor (VEGF), which is one of the most potent angiogenic factors, has been shown to play a pivotal role in tumor angiogenesis, including hepatocellular carcinoma (HCC). The effects of VEGF are mediated mainly through two distinct receptors, flt-1 and KDR/Flk-1. It has been suggested that KDR/Flk-1 plays an important role in tumor development. However, the role of KDR/Flk-1 in HCC has not been examined. We previously reported that VEGF tightly regulated murine HCC development, based on the results of a study using a retroviral tetracycline-regulated (Retro-Tet) gene expression system. This system allows VEGF gene expression to be manipulated in vivo by providing tetracycline in the drinking water. In the present study, we combined the KDR/Flk-1-specific neutralizing monoclonal antibody (KDR/Flk-1mAb) and the Retro-Tet system to elucidate the role of KDR/Flk-1 in VEGF-induced tumor development and angiogenesis in a murine HCC experimental model. In a xenograft study, tumor augmentation induced by VEGF overexpression was almost abolished by means of KDR/Flk-1mAb treatment, with accompanying inhibition of angiogenesis, KDR/Flk-1 autophosphorylation, but not interference of flt-1 activation. This inhibitory effect was achieved even on established tumors and regardless of whether the tumor size was small or large. On the contrary, KDR/Flk-1mAb treatment significantly increased the apoptosis in the tumor. With orthotopic transplantation, KDR/Flk-1mAb also inhibited HCC development in the liver. These results suggest that KDR/Flk-1 is a major regulator of VEGF-mediated HCC development and angiogenesis not only at the initial stage, but also after the tumor has fully developed.

Animals↗
PubMed1999

Dummy use, thumb sucking, mouth breathing and cot death.

UNLABELLED: In the Netherlands a case control study into cot death was undertaken as part of the European Concerted Action on sudden infant death syndrome. Children between 1 week and 2 years of age who died suddenly and unexpectedly were reported. Non cot death cases were excluded after a consensus by three pathologists. The study comprised 73 cot death cases and two controls per case, matched for date of birth. Compared to national data, the coverage was 91%. We investigated whether in the Netherlands new risk or preventive factors might have emerged. The present report focuses on the relative risks of dummy use, thumb sucking, breast versus bottle feeding, and sleeping with the mouth open. CONCLUSION: Dummy use seems to be an important preventive factor for cot death in the Netherlands, independent of other risk factors such as prone sleeping and bedding. We recommend dummy use at least for bottle-fed infants. We found no indication that dummies influence the frequency or duration of breast feeding but more data are needed. Mouth breathing appears to be associated with an increased risk for cot death, but again further research is needed.

Bottle Feeding↗
PubMed1999

The effect of a second-generation 3D endoscope on the laparoscopic precision of novices and experienced surgeons.

BACKGROUND: Endoscopic surgeons rely on visual feedback to control their movements but lack stereopsis, an important depth cue. Previous three-dimensional (3D) systems alternated images on a two-dimensional (2D) screen, which was uncomfortable for surgeons. A second-generation 3D system provides continuous stereoscopic images on a monitor suspended at arm's length. We studied its effect on the laparoscopic precision of novices and experienced surgeons. METHODS: Experienced laparoscopic surgeons (n = 12) and novices (n = 16) performed a total of 672 tasks in 2D, 3D, and under direct vision. Precision was assessed using the Imperial College Surgical Assessment Device (ICSAD), which generates objective scores of performance by analyzing the movements of surgical instruments. RESULTS: We found that 2D endoscopic vision impaired performance by 35-100% when compared with direct vision, whereas 3D reduced this endoscopic handicap by 41-53% in novices and experienced surgeons (p < 0.03). No side effects were reported with the new 3D system. Even in 2D, novices performed better with an image at arm's length (p < 0. 03). CONCLUSIONS: Second-generation 3D significantly improved the laparoscopic precision of novices and experienced surgeons, without the side effects reported from previous systems. This technology is expected to improve the ease and safety of laparoscopic surgery.

Adolescent↗