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The effect of dam strain on the craniofacial morphogenesis of CL/Fr mouse fetuses.

The embryo transfer technique and cephalometry were used to investigate the effect of dam strain in intrauterine craniofacial growth and the severity of cleft lip and palate (CLP) in a CLP-susceptible CL/Fr strain of embryos. The CL/Fr strain of embryos at early blastocyst stage was transferred to the same dam strain and to the CLP-resistant C57BL dam strain. On the 18th gestational day, each dam was laparotomized to take out the fetuses. The spontaneous incidence of CLP in the fetuses was checked and a cephalometric observation of the craniofacial complex of each fetus was done just after laparotomy. The dorsoventral craniofacial size of the unaffected fetuses and the severity of CLP i the affected ones were compared between both dam strains. The following results were obtained: 1) The overall craniofacial sizes of the unaffected fetuses observed in the CL/Fr dam strain were significantly smaller than those seen in the C57/BL dam strain. Those of the affected fetuses observed in the CL/Fr dam strain were smaller than those seen in the C57BL dam strain although the interstrain difference was not significant. 20 The dam strain had a highly significant effect on the craniofacial size of the unaffected fetuses. 3) The CLP frequency in the CL/Fr dam strain was significantly higher than that in the C57BL dam strain. 4) The severity of CLP in the affected fetuses observed in the CL/Fr dam strain was significantly more serious than that seen in the C57BL dam strain. These results indicated that the CLP-susceptible CL/Fr dam strain retarded the intrauterine craniofacial growth of the fetuses and that the cleft condition in the affected fetuses observed in the CL/Fr dam strain was more seriously affected than that seen in the CLP-resistant C57BL dam strain. Thus, it can be concluded that the effect of the dam strain played an important role in the craniofacial morphogenesis of the CL/Fr strain of mouse fetuses that developed from the embryo transferred to the CL/Fr and C57BL dam strains along with the genotype of embryos.

Animals↗
PubMed2001

Second-trimester ultrasound to detect fetuses with Down syndrome: a meta-analysis.

CONTEXT: Second-trimester prenatal ultrasound is widely used in an attempt to detect Down syndrome in fetuses, but the accuracy of this method is unknown. OBJECTIVE: To determine the accuracy of second-trimester ultrasound in detecting Down syndrome in fetuses. DATA SOURCES: English-language articles published between 1980 and February 1999 identified through MEDLINE and manual searches. STUDY SELECTION: Studies were included if they recorded second-trimester findings of ultrasonographic markers, chromosomal abnormalities, and clinical outcomes for a well-described sample of women. A total of 56 articles describing 1930 fetuses with Down syndrome and 130 365 unaffected fetuses were included. DATA EXTRACTION: Articles were independently reviewed, selected, and abstracted by 2 reviewers. Discrepancies in data abstraction were resolved by consensus with a third reviewer. Overall estimates of sensitivity, specificity, and positive and negative likelihood ratios were calculated for the following markers: choroid plexus cyst, thickened nuchal fold, echogenic intracardiac focus, echogenic bowel, renal pyelectasis, and humeral and femoral shortening. Results were stratified by whether markers were identified in isolation or in conjunction with fetal structural malformations. DATA SYNTHESIS: When ultrasonographic markers were observed without associated fetal structural malformations, sensitivity for each was low (range, 1%-16%), and most fetuses with such markers had normal outcomes. A thickened nuchal fold was the most accurate marker for discriminating between unaffected and affected fetuses and was associated with an approximately 17-fold increased risk of Down syndrome. If a thickened nuchal fold is used to screen for Down syndrome, 15 893 average-risk women or 6818 high-risk women would need to be screened for each case of Down syndrome identified. For each of the other 6 markers, when observed without associated structural malformations, the marker had marginal impact on the risk of Down syndrome. Because the markers were detected in only a small number of affected fetuses, the likelihood of Down syndrome did not decrease substantially after normal examination findings (none of the negative likelihood ratios were significant). CONCLUSIONS: A thickened nuchal fold in the second trimester may be useful in distinguishing unaffected fetuses from those with Down syndrome, but the overall sensitivity of this finding is too low for it to be a practical screening test for Down syndrome. When observed without associated structural malformations, the remaining ultrasonographic markers could not discriminate well between unaffected fetuses and those with Down syndrome. Using these markers as a basis for deciding to offer amniocentesis will result in more fetal losses than cases of Down syndrome detected, and will lead to a decrease in the prenatal detection of fetuses with Down syndrome.

Down Syndrome↗
PubMed1990

Central nervous system lesions in the Wistar rat fetus following direct fetal injections of cadmium.

During embryogenesis, maternal administration of cadmium (Cd) produces teratogenic effects, including hydrocephalus (HC), whereas later in gestation (during the fetal period), such effects have not been reported. Since there is little placental transfer of Cd late in gestation, such differences in response could be due to a lower Cd concentration in the fetus compared with the embryo after maternal Cd exposure, or could be due to a decreased sensitivity of the fetal central nervous system (CNS) to Cd. To test the susceptibility of the late gestational CNS to Cd, day 19 (sperm plug = day 0) rat fetuses were directly injected i.p. with CdCl2 (165, 100, 50 nmoles/fetus in 5 microliters saline). All fetuses in one horn were treated with Cd, while fetuses in the other horn were treated with saline. Fetuses were collected on day 21, grossly examined, weighed, fixed in Bouin's fixative, and later razor sectioned. Cd did not affect fetal viability or body weight. However, Cd caused a dose-dependent increase in hydrocephalus, with the total number of fetuses showing moderate to severe HC being 0/45, 0/11, 6/10, and 18/20 for controls, low, medium, and high doses, respectively. Mild HC was noted in one control and two low Cd fetuses. Brain necrosis was correlated with hydrocephalus, being observed in 0/45, 0/11, 5/10, and 16/20 fetuses, respectively. In medium-dose fetuses without HC or brain necrosis, extravasation of erythrocytes was noted histologically within the cortical parenchyma, suggesting that hemorrhaging may lead to brain necrosis and hydrocephalus in Cd-exposed fetuses. Thus, the fetal CNS is susceptible to the toxic effects of Cd.

Animals↗
PubMed1995

Epidermal melanocytes in normal and tyrosinase-negative oculocutaneous albinism fetuses.

In tyrosinase-negative (type IA) oculocutaneous albinism (tyr(-) OCA) fetuses the development of melanocytes has not been fully elucidated. We analysed the distribution of melanocytes in skin samples from a fetus with tyr(-) OCA and from four normal fetuses. Skin samples obtained from 12 different body sites of each fetus were examined by transmission electron microscopy, an electron microscopic DOPA reaction test and immunohistochemistry. No S100 protein-positive cells were detected in any sample. There were fewer HMB-45-positive melanocytes in the skin of the tyr(-) OCA fetus than in the skin of normal fetuses from all body sites sampled. The greatest number of HMB-45-positive melanocytes was present in samples from the scalp of the normal fetuses and in those from the lower limbs of the tyr(-) OCA fetus. Very few melanocytes were detected immunohistochemically in samples from the soles and palms, though their presence was confirmed by transmission electron microscopy. The electron microscopic DOPA reaction test enhanced the melanization of melanocytes in samples from the normal fetuses but not in those from the tyr(-) OCA fetus. Postembedding immunogold electron microscopy using the HMB-45 antibody revealed that the HMB-45 antigen was localized mainly on stages I and II melanosomes. The presence of epidermal melanocytes in samples from all fetal body areas obtained at 17-21 weeks of gestation justifies the use of the electron microscopic DOPA reaction test in the prenatal diagnosis of tyr(-) OCA.

Albinism, Oculocutaneous↗
PubMed1995

Behavioural development and Doppler velocimetry in relation to perinatal outcome in small for dates fetuses.

Twenty-two small for dates (SFD) fetuses and 96 fetuses from uncomplicated pregnancies were monitored on two occasions between 27 and 32 weeks and the second time between 33 and 36 weeks of gestation by studying the development of behavioural states (coincidence 1F and 2F; no coincidence) and umbilical artery Doppler waveform patterns (UA; Resistance Index, RI). Data were related to neurological outcome at 8 months after birth. The purpose of this study was to investigate if the development of behavioural state is disturbed in SFD fetuses and if SFD fetuses who needed to be delivered early and/or had abnormal neurological outcome showed different state development and RI than SFD fetuses delivered later in pregnancy or with normal neurological outcome. Finally, we studied if there was a relationship between state development and RI. At 27-32 weeks of gestation the percentage of coincidence 2F (C2F%) was lower and the percentage of coincidence 1F (C1F%) and no coincidence (NOC%) were higher in the SFD fetuses than in the control group. At 33-36 weeks C2F% was lower and NOC% was higher but not statistically different (P = 0.2 and P = 0.07, respectively). SFD fetuses who needed to be delivered early had poorer state development than SFD fetuses at lower risk and infants who were abnormal at 8 months of life showed a higher C1F% and lower C2F% at 27-32 weeks. There were significant correlations between RI on the one hand and NOC% (r = 0.62) and C2F% (r = -0.48) on the other hand at 27-32 weeks in the subgroup with abnormal neurological outcome. In conclusion, in SFD fetuses there are disturbances in the development of behavioural states as well in the distribution of the periods of coincidence (with a decrease in C2F% and an increase in C1F%). Poorest state development is present in SFD fetuses at highest risk and in this group there appears to be a significant relationship between the degree of utero-placental insufficiency (RI) and disturbances in behavioural development.

Behavior↗
PubMed2004

Quantitative assessment of right ventricular function using doppler tissue imaging in fetuses with and without heart failure.

BACKGROUND: Previous reports have established the use of Doppler tissue imaging (DTI) for noninvasive assessment of ventricular function, but the technique has not been validated for diagnosis of fetal cardiac failure. OBJECTIVE: The purpose of this study was to assess right ventricular (RV) function in fetuses with heart failure using DTI. METHODS: In all, 43 fetuses (36 control, 7 heart failure) were assessed using pulsed Doppler echocardiography combined with DTI. RV peak myocardial velocities during early diastole (Ea), atrial contraction, and systole were measured; and tricuspid peak velocities during early diastole (E) and atrial contraction. The ratio of E/Ea was used as an index of filling pressure were measured. From DTI, a Doppler-derived index of combined systolic/diastolic myocardial performance (DTI-Tei index) was measured. RESULTS: Compared with control fetuses, the mean Ea was significantly lower and the mean E was significantly higher in fetuses with heart failure, although these parameters did overlap between the 2 groups. The mean RV myocardial wall-motion velocity during atrial contraction, ratio of Ea/RV myocardial wall-motion velocity during atrial contraction, and RV myocardial wall-motion velocity during systole did not differ between the 2 groups. Compared with control fetuses, the mean E/Ea was significantly higher (9.71 +/- 0.91 vs 6.20 +/- 0.97; P <.0001) and the mean DTI-Tei index was significantly greater (0.79 +/- 0.11 vs 0.55 +/- 0.05; P <.0001) in fetuses with heart failure. In addition, the DTI-Tei index z score was >2 in all fetuses with heart failure. CONCLUSIONS: This study demonstrated a clinically important application of DTI-derived tricuspid annular velocities in fetuses with heart failure. Although DTI velocities were not sufficiently sensitive to identify fetuses with heart failure versus control fetuses, DTI-Tei index and E/Ea were useful and sensitive indicators of global RV dysfunction.

Blood Flow Velocity↗
PubMed1992

Inferior vena cava flow velocity waveforms in appropriate- and small-for-gestational-age fetuses.

Reference ranges of inferior vena cava flow velocities were constructed from a cross-sectional study of 118 appropriate-for-gestational-age fetuses of 18 to 40 weeks of gestation. Blood flow velocity waveforms were recorded with color and pulsed Doppler equipment. Peak velocities and time velocity integrals were measured from inferior vena cava during systole, early diastole, and atrial contraction. The systolic-to-diastolic ratios between the peak velocities and time velocity integrals were calculated, and the reverse flow with atrial contraction was quantified as the percentage of forward flow (percentage of reverse flow). Recordings were also obtained from 79 small-for-gestational-age fetuses free of structural and chromosomal abnormalities, divided into three groups according to umbilical artery velocity waveforms: normal pulsatility index values (group 1, n = 26), pulsatility index greater than 95th percentile of our reference limits but presence of end-diastolic velocities (group 2, n = 33), and absence of end-diastolic velocities (group 3, n = 20). Fourteen fetuses of groups 2 and 3 were also studied at weekly intervals until the onset of antepartum late heart rate decelerations. In appropriate-for-gestational-age fetuses no changes were evident in peak velocities and time velocity integrals ratios, whereas the percentage of reverse flow significantly decreased with gestation. No significant differences were found between these values and those obtained in small-for-gestational-age fetuses of group 1. A significant increase of peak velocities and time velocity integrals ratios and of percentage of reverse flow was evidenced in fetuses of both group 2 and 3. The fetuses of groups 2 and 3 with a percentage of reverse flow above the 95% confidence interval showed a poorer perinatal outcome when compared with the fetuses of the same groups but with values inside the normal range. In the 14 fetuses longitudinally followed up until the onset of late heart rate decelerations a significant and progressive increase of peak velocities and time velocity integrals ratios and percentage of reverse flow was evidenced in spite of minimal changes in the pulsatility index from both umbilical artery and different peripheral fetal vessels. This study presents evidence that in small-for-gestational-age fetuses with abnormal Doppler-measured placental resistance the modified flow velocity patterns in the inferior vena cava seem to deteriorate progressively with advancing gestation.

Blood Flow Velocity↗
PubMed1999

Venous Doppler in the sonographic surveillance of fetuses with supraventricular tachycardia.

OBJECTIVE: In animals and adult humans sustained supraventricular tachycardia leads to myocardial remodelling and dysfunction, persisting even after drug-induced cardioversion to sinus rhythm. This study was undertaken, to evaluate cardiac function in the human fetus by noninvasive determination of the degree of AV valve incompetence and venous blood flow, in order to enhance understanding of the pathophysiology of fetal supraventricular tachycardia. Furthermore, we wanted to determine the usefulness of these methods in the surveillance of these fetuses before and after drug-induced cardioversion. STUDY DESIGN: Eleven fetuses with supraventricular tachycardia between 24 and 35 weeks of gestation were studied. AV valve regurgitation and venous Doppler waveforms of the inferior vena cava and ductus venosus were evaluated before and after conversion to sinus rhythm. RESULTS: Three different groups of fetuses could be distinguished. The first group consisted of four fetuses with neither signs of hydrops nor AV valve incompetence. Venous indices normalized within one to four days (median 2.5 days) after conversion to sinus rhythm. The second group contained two fetuses with hydrops, but without AV valve incompetence. Their venous indices normalized at the day of conversion and 3 days later, respectively (median 1.5 days). The last group of five fetuses consisted of four fetuses with hydrops and AV valve regurgitation during supraventricular tachycardia. In one fetus with hydrops and supraventricular tachycardia the fetal heart rate was continuously decreased to a level of 160-190 beats/min under drug treatment, but no conversion to sinus rhythm occurred. The venous indices of these fetuses normalized within 12-42 days (median 27 days) after conversion. CONCLUSION: Our data suggest that in sustained fetal supraventricular tachycardia alterations of myocardial function similar to tachycardia-induced 'cardiomyopathy' occur. The severity of tachycardia-induced changes of cardiac function is reflected by the degree and persistence of AV valve incompetence, as well as by alterations of the venous blood flow pattern. Under clinical conditions, the latter can readily and well reproducibly be demonstrated by calculating the venous blood flow indices of the inferior vena cava and ductus venosus.

Anti-Arrhythmia Agents↗
PubMed2002

Monoclonal antibodies specific for Campylobacter fetus lipopolysaccharides.

Four monoclonal antibodies (mAbs) (M1357, M1360, M1823 and M1825) which reacted with Campylobacter fetus lipopolysaccharide (LPS) core region epitopes were produced and characterized. Reactivity of these mAbs with C. fetus core LPS epitopes was determined by enzyme-linked immunosorbent assay (ELISA) with whole cell proteinase K digests and phenol-water extracted LPS, and by immunoblotting with proteinase K digests. The specificities of the four mAbs were evaluated using an indirect ELISA. One of the mAbs reacted with 42 and three of the mAbs reacted with 41 of the 42 C. fetus strains examined. No reaction was observed between the four mAbs and 32 non-C. fetus bacteria tested, with the exception of one mAb with one organism. The four mAbs reacted with serotype A and B strains indicating the presence of shared epitopes in C. fetus LPS core oligosaccharides. The specificities of three mAbs previously produced to C. fetus LPS O-antigens (M1177, M1183 and M1194) were also evaluated and no reaction was observed with these mAbs and the 32 non-C. fetus bacteria tested. Strong immunofluorescence reactions were observed with the anti-O chain mAbs and selected C. fetus strains of the homologous serotype. These anti-LPS core oligosaccharide and anti-LPS O chain mAbs are highly specific for C. fetus and are potentially useful as immunodiagnostic reagents for detection, identification and characterization of C. fetus.

Animals↗
PubMed1997

Fetal redistribution of blood flow and amniotic fluid volume in growth-retarded fetuses.

Our purpose was to assess the relationship between the fetal redistribution of blood flow and the amount of amniotic fluid in appropriate-for gestational-age fetuses and growth-retarded fetuses. Blood flow velocity waveforms of the umbilical artery, descending aorta, middle cerebral artery, renal artery and uterine artery were recorded using pulsed Doppler ultrasonography in 100 appropriate-for gestational age fetuses and 39 growth-retarded fetuses. The pulsatility index (PI) values and the amount of amniotic fluid were compared between the two groups. The PI values of the umbilical artery and renal artery were significantly higher in appropriate for gestational-age-fetuses with oligohydraminos than in fetuses with an adequate amount of amniotic fluid. The PI values of the umbilical artery and renal artery were significantly higher and the PI of the middle cerebral artery was significantly lower in growth-retarded fetuses with oligohydramnios than in fetuses with an adequate amount of amniotic fluid. Furthermore, there was a significant negative correlation between the PI value of the renal artery and the vertical diameter of amniotic fluid, and between the PI value of the renal artery and the amniotic fluid index. The PI value of the renal artery was related to the amount of amniotic fluid in growth-retarded fetuses, and the same relationship was demonstrated in appropriate-for gestational age fetuses.

Amniotic Fluid↗
PubMed1996

The second-trimester fetus with Down syndrome: detection using sonographic features.

Down syndrome (trisomy 21) is the most common chromosomal abnormality among liveborn infants in the United States, with an incidence of 1/700 to 1/1000 births. Its incidence rises with maternal age, thus prompting the current practice of offering genetic amniocentesis to women 35 years of age or older. However, even if every pregnant woman of advanced maternal age (> or = 35 years) were to undergo karyotyping, only 20% of fetuses with Down syndrome would be detected. Until approximately 10 years ago, karyotyping of the fetuses of older women was practically the only antenatal method of identifying any fetus with trisomy 21. In 1984, Cuckle and associates first reported the use of a low level of serum alpha-fetoprotein as a screening tool for identifying affected fetuses in younger women. Combining the criteria based on both maternal age and serum alpha-fetoprotein resulted in identifying 40% of fetuses with Down syndrome, as well as 6.8% of unaffected fetuses. Still, at least 60% of fetuses with Down syndrome remained undetected with these screening techniques. It is logical to expect that sonographic imaging of the second-trimester fetus itself would result in the optimal detection of the anatomical features of Down syndrome (Figure 1). To this end, many researchers have attempted to identify sonographic findings that would serve to detect fetuses likely to have Down syndrome. This review summarizes the characteristic sonographic findings associated with an increased risk of a fetus having trisomy 21.

Dilatation, Pathologic↗
PubMed2001

Ductus venosus Doppler study in fetuses with homozygous alpha-thalassemia-1 at 12 to 13 weeks of gestation.

OBJECTIVE: Fetuses affected by homozygous alpha-thalassemia-1 are anemic from the first trimester of pregnancy. We investigated ductus venosus Doppler velocimetry in these affected fetuses at 12-13 weeks of gestation. DESIGN: Prospective observational study. SUBJECTS: Women referred for the prenatal diagnosis of homozygous alpha-thalassemia-1 before 14 weeks of gestation. METHODS: All fetuses underwent pulsed Doppler investigations following color flow mapping at 12 or 13 weeks of gestation. Homozygous alpha-thalassemia-1 was diagnosed by DNA or hemoglobin study. The ductus venosus Doppler indices--Vmax (peak velocity during ventricular systole), Vmin (minimum forward velocity during atrial systole), TAMX (time-averaged maximum velocity), PIV (pulsatility index for veins, Vmax-Vmin/TAMX), PLI (preload index, Vmax-Vmin/Vmax) and Vmax/Vmin ratio--were compared between the affected fetuses and fetuses unaffected by homozygous alpha-thalassemia-1. RESULTS: Between June 1998 and October 1999, 102 eligible women were recruited. Fetal ductus venosus Doppler study was successful in 96 pregnancies (94%). Of these, 20 fetuses were affected by homozygous alpha-thalassemia-1. None of them showed hydropic changes at the time of Doppler study. The affected fetuses had significantly higher ducts venosus Vmax (30% increase), Vmin (50% increase) and TAMX (20% increase) and significantly lower Vmax/Vmin ratio, PIV and PLI values. CONCLUSION: Fetuses affected by homozygous alpha-thalassemia-1 at 12-13 weeks had increased forward flow velocities in the ductus venosus throughout the cardiac cycle. The increase of venous return is consistent with our previous report of cardiac dilatation and an increase of cardiac output in the affected fetuses at this stage as a compensatory mechanism for anemia and hypoxia. However, extensive overlap of the ductus venosus Doppler indices between affected and unaffected fetuses precludes its use in predicting anemia at 12-13 weeks.

Blood Flow Velocity↗
PubMed2002

Development of skeletal muscle and expression of candidate genes in bovine fetuses from embryos produced in vivo or in vitro.

The objectives of this study were to determine the effects of in vitro embryo production on histological development and gene expression in the skeletal muscle of bovine fetuses during late gestation. Blastocysts produced in vivo were obtained from superovulated Holstein cows. Blastocysts produced in vitro were obtained from oocytes of Holstein cows that were matured and fertilized in vitro. Single blastocysts were transferred into heifers at a synchronized estrous and fetuses were recovered at Day 222 of gestation (n = 12 each for in vivo and in vitro). Samples of semitendinosus muscle were obtained for histological analysis and assessment of gene expression. Individual muscle sections were stained for the assessment of primary muscle fibers, secondary muscle fibers, or total muscle fibers. Semiquantitative reverse transcription-polymerase chain reaction assays were performed for 5 different candidate genes. The ratio of secondary-to-primary fiber number was greater in fetuses from embryos produced in vitro compared with fetuses from embryos produced in vivo. Similarly, the ratio of secondary-to-primary fiber volume density tended to be greater in fetuses from embryos produced in vitro. The proportional volume of tissue present between myofibrils was greater in fetuses from embryos produced in vitro. The expression of mRNA for myostatin was decreased in skeletal muscle of fetuses in the in vitro group compared with controls. The expression of mRNA for glyceraldehyde-3-phosphate dehydrogenase tended to be increased in skeletal muscle of fetuses in the in vitro treatment group. There was no effect of treatment on the expression of mRNAs for myf-5, myoD, or myogenin. In conclusion, in vitro production of embryos resulted in fetuses with altered development of skeletal muscle fibers. Myostatin was identified as the candidate gene whose expression may contribute to the observed changes in muscle development of these fetuses.

Animals↗
PubMed1992

Differentiation of the subspecies of Campylobacter fetus by genomic sizing.

Campylobacter fetus subsp. fetus and C. fetus subsp. venerealis are currently differentiated by tolerance to glycine and by their epidemiology. Analysis of C. fetus DNA by pulsed-field gel electrophoresis, after digestion with the restriction endonucleases SmaI and SalI, was used to differentiate between the subspecies. All strains presently identified as C. fetus subsp. fetus had a genomic size of 1.1 Mb, whereas the majority of the C. fetus subsp. venerealis strains had a genomic size of 1.3 Mb. An additional group of strains, which were previously described as C. fetus subsp. venerealis biovar "intermedius" and were able to tolerate higher concentrations of glycine than the rest of the C. fetus subsp. venerealis strains, had an average genome size of 1.5 Mb. We suggest that pulsed-field gel electrophoresis may be useful as an additional aid in the differentiation of C. fetus strains at the subspecies level.

Campylobacter fetus↗
PubMed1996

Biological characterization of Campylobacter fetus lipopolysaccharides.

Lipopolysaccharides (LPS) of three strains of Campylobacter fetus (subspp. fetus and venerealis, and serotypes A and B), a bacterium of veterinary importance but also a cause of various infections in humans, were assessed for their ability to induce mitogenicity, gelation of Limulus amebocyte lysate, lethal toxicity in mice, and pyrogenicity in rabbits. All C. fetus LPS exhibited activities lower than those of Salmonella typhimurium LPS. LPS of C. fetus subsp. fetus serotype A had the lowest activity in all assays. Since the majority of C. fetus subsp. fetus isolates from humans are serotype A, the lower biological activities of this LPS may aid the pathogenesis of such strains. The lower activities of C. fetus LPS compared with those of S. typhimurium LPS may reflect the presence of longer fatty acid chains in the lipid A of C. fetus LPS, whereas interstrain differences in C. fetus LPS bioactivities may be related to some property influenced by composition of the saccharide moiety.

Animals↗
PubMed1998

Cloning of a sapB homologue (sapB2) encoding a putative 112-kDa Campylobacter fetus S-layer protein and its use for identification and molecular genotyping.

A sap gene encoding a surface layer protein was isolated from a Campylobacter fetus ssp. fetus CIP 53.96T cosmid library. This sap gene, which shows significant homology with the sapB conserved region, was named sapB2. The complete ORF of 3339 nucleotides encodes a 1112-amino acid polypeptide with a calculated molecular mass of 112 kDa. High homology with the sapB gene was found in a region beginning 67 bp before the ORF and proceeding 546 bp into the ORF. Similarly, 98% homology with the sapA2 gene was observed in a 2038-bp region beginning 540 bp after the initiation codon. In the present study, we show that this sapB2 gene has two main interesting features: the 5' end of the region which presents high homology with the sapA2 homologue was found to be present in every C. fetus strain, and the fragment (IG01) comprising the region which presents homology with the sapB conserved region and the 5' end of the sapA2 homologue region, when used as a probe, can reveal genomic polymorphism among C. fetus strains. We exploited these features to develop a PCR assay for the specific detection of C. fetus and to set up a method for typing C. fetus isolates. The PCR assay was found to be species-specific. Oligonucleotide primers derived from the 5' end of sapA2 homologue region were used in a polymerase chain reaction test on genomic DNA extracted from 101 Campylobacter fetus, 18 Campylobacter non-fetus and seven non-Campylobacter strains. A 220-bp fragment was amplified only when C. fetus DNA was used as a target. In Southern blot analysis, the IG01 probe was found to hybridize only with DNA extracted from C. fetus strains. Moreover, IG01 hybridized with several fragments of HindIII-digested DNA, giving a specific pattern for each strain.

Amino Acid Sequence↗
PubMed2003

Cardiovascular and endocrine responses to acute hypoxaemia during and following dexamethasone infusion in the ovine fetus.

This study investigated the effects of fetal treatment with dexamethasone on ovine fetal cardiovascular defence responses to acute hypoxaemia, occurring either during or 48 h following the period of glucocorticoid exposure. To address the mechanisms underlying these responses, chemoreflex function and plasma concentrations of catecholamines, neuropeptide Y (NPY) and vasopressin were measured. Under general halothane anaesthesia, 26 Welsh Mountain sheep fetuses were surgically prepared for long-term recording at between 117 and 120 days of gestation (dGA; term is approximately 145 days) with vascular catheters and a Transonic flow probe around a femoral artery. Following at least 5 days of recovery, fetuses were randomly assigned to one of two experimental groups. After 48 h of baseline recording, at 125 +/- 1 dGA, half of the fetuses (n = 13) were continuously infused I.V. with dexamethasone for 48 h at a rate of 2.06 +/- 0.13 microg kg-1 h-1. The remaining 13 fetuses were infused with heparinized saline at the same rate (controls). At 127 +/- 1 dGA, 2 days from the onset of infusions, seven fetuses from each group were subjected to 1 h of acute hypoxaemia. At 129 +/- 1 dGA, 2 days after the end of infusions, six fetuses from each group were subjected to 1 h of acute hypoxaemia. Similar reductions in fetal partial pressure of arterial oxygen occurred in control and dexamethasone-treated fetuses during the acute hypoxaemia protocols. In control fetuses, acute hypoxaemia led to transient bradycardia, femoral vasoconstriction and significant increases in plasma concentrations of catecholamines, vasopressin and NPY. In fetuses subjected to acute hypoxaemia during dexamethasone treatment, the increase in plasma NPY was enhanced, the bradycardic response was prolonged, and the plasma catecholamine and vasopressin responses were diminished. In fetuses subjected to acute hypoxaemia 48 h following dexamethasone treatment, femoral vasoconstriction and plasma catecholamine and vasopressin responses were enhanced, whilst the prolonged bradycardia and augmented plasma NPY responses persisted. These data show that fetal treatment with dexamethasone modifies the pattern and magnitude of fetal cardiovascular responses to acute oxygen deprivation. Modifications to different mechanisms mediating the fetal defence responses to acute hypoxaemia that occur during dexamethasone treatment may reverse, persist or even become enhanced by 48 h following the treatment period.

Acid-Base Equilibrium↗
PubMed1985

Induction of premature delivery in sheep following infusion of cortisol to the fetus. I. The effect of maternal administration of progestagens.

Premature induction of delivery in fetuses infused with graded doses of cortisol was brought about in 123.5 +/- 7.7 h (mean +/- SEM, n = 6) after the start of cortisol infusion. This treatment caused a rise in fetal plasma cortisol similar to that observed at normal delivery. Maternal and fetal progesterone and 20 alpha-dihydroprogesterone concentrations decreased to basal levels during infusion of cortisol to the fetus. Induction of premature delivery was delayed or prevented by concomitant treatment of the ewe with progestagen. Maternal intramuscular injection of 100 mg progesterone, 2 times daily, prevented delivery in four of four ewes treated during the time that cortisol was infused into the fetus (11-13 days). Maternal plasma progesterone and 20 alpha-dihydroprogesterone concentrations were maintained during this period, but fetal plasma progesterone concentrations decreased to the same extent as in the fetuses infused with cortisol alone. A single intramuscular injection of 250 mg of medroxyprogesterone acetate to ewes on the day before commencement of infusion of cortisol to the fetus prevented delivery in four of six ewes during the time that cortisol was infused for 9, 13, 14, and 15 days, respectively. One ewe delivered a live lamb at 133.5 h and another at 147.7 h after the start of infusion of cortisol to the fetus. Maternal and fetal plasma cortisol, progesterone, and 20 alpha-dihydroprogesterone concentrations were similar to those observed during infusion of cortisol alone to the fetus. Although fetal cortisol concentrations rose in a similar fashion, and to a similar extent, in all three groups during infusion of cortisol to the fetus, fetal 11-desoxycortisol concentrations only rose above basal levels close to the time of delivery in cortisol-infused fetuses or, in the progestagen-treated groups, when the fetus showed signs of being stressed.

20-alpha-Dihydroprogesterone↗