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Biomedical subjects

J Bang

Publications and source records attributed to J Bang.

At least 37 records · Page 2Linked to original sources
PubMed1994

Current status of research on biophysical effects of ultrasound.

This overview of bioeffects of ultrasound presents some key aspects of selected papers dealing with biophysical end-points. Its purpose is to establish a basis for exposure and dosimetric standards for medical ultrasonic equipment. It is intended to provide essential background resource material for the medical/scientific community, and more specifically for scientific working groups. This document was prepared by members of the Safety Committee of the World Federation for Ultrasound in Medicine and Biology. It was produced as a resource document in response to a request for information by Working Group 12 (Ultrasound exposure parameters) of the International Electrotechnical Commission Technical Committee 87, Ultrasonics. IEC TC 87, WG12 is the working group responsible for generating international standards for the classification of equipment by its acoustic fields based on safety thresholds. Our paper is intended to update and supplement information on the thermal mechanism provided in the publication, "WFUMB Symposium on Safety and Standardisation in Medical Ultrasound: Issues and Recommendations Regarding Thermal Mechanisms for Biological Effects of Ultrasound" (WFUMB 1992). It also provides an overview of trends in research into nonthermal mechanisms as a preliminary to the next WFUMB Symposium on Safety of Medical Ultrasound when this subject will be examined in detail by a select group of international experts. The WFUMB-sponsored workshop will take place in Utsunomiya, Japan during 11-15th July, 1994. The purpose of the meeting is to evaluate the scientific literature and to formulate internationally accepted recommendations on the safe use of diagnostic ultrasound that may be endorsed as official policy of the WFUMB. It should be noted that the current publication is not intended for review or endorsement as an official WFUMB document. It is produced as a scientific paper by individuals who are members of the WFUMB Safety Committee, and it therefore represents the opinions of the authors. Nevertheless, during the preparation of this document, contributions were received from members of the International Electrotechnical Commission Technical Committee 87 as well as many other individual experts, and the authors sincerely acknowledge their support.

Air↗
PubMed1993

[Early amniocentesis].

Genetic amniocentesis performed at 7-14 weeks of gestation was studied in a series of 138 patients of whom 50 wanted termination of pregnancy (< or = 12 weeks). The material for analysis consisted of 132 samples due to two sampling failures and four samples being handled incorrectly. Forty-eight samples (36 percent) were taken at 7-12 weeks of gestation, mainly transvaginally (36/48:75 percent). The success rate of culture and karyotyping increased with the duration of pregnancy, but was only satisfactory from week 11 onwards. The time until harvest was then 14-15 days. The transvaginal approach is easy to perform and was accepted by the women, but we experienced bacterial or fungal overgrowth in 17 percent of these samples, whereas no infection occurred in the samples taken transabdominally (n = 96). We conclude that genetic amniocentesis is feasible from week 11, but further studies concerning side effects, especially focusing on the procedure-related abortion risk, should be carried out before early amniocentesis is routinely applied.

Adolescent↗
PubMed1992

Genetic amniocentesis at 7-14 weeks of gestation.

Genetic amniocentesis performed at 7-14 weeks of gestation was studied in a series of 138 patients of whom 50 wanted termination of pregnancy (less than or equal to 12 weeks). The material for analysis consisted of 132 samples due to two sampling failures and four samples being handled incorrectly. Forty-eight samples (36 per cent) were taken at 7-12 weeks of gestation, mainly transvaginally (36/48: 75 per cent). The success rate of culture and karyotyping increased with the duration of pregnancy, but was only satisfactory from week 11 onwards. The time until harvest was then 14-15 days. The transvaginal approach is easy to perform and was accepted by the women, but we experienced bacterial or fungal overgrowth in 17 per cent of these samples, whereas no infection occurred in the samples taken transabdominally (n = 96). We conclude that genetic amniocentesis is feasible from week 11, but further studies concerning side effects, especially focusing on the procedure-related abortion risk, should be carried out before early amniocentesis is routinely applied.

Abdomen↗
PubMed1991

Early prenatal diagnosis of the fragile site at Xq27.3 associated with Martin-Bell syndrome.

Early prenatal diagnosis of the fragile X was attempted in 44 pregnancies, including one twin pregnancy at risk of Martin-Bell (MB) syndrome. The sex ratio was 24M:21F. The fragile site was reproducibly demonstrated in cultured chorionic villus (CV) cells in eight male and five female fetuses. Six of the male and three of the female fetuses were terminated. Simultaneous RFLP analysis provided confirmative data with flanking DNA markers in 3 of 13 analysed cases. Recombination and/or non-informativeness at available distal and/or proximal loci were found in nine cases. In one male fetus, discordance between the haplotype and cytogenetics (fragile-X-negative) suggested the presence of a normal male transmitter, a double meiotic cross-over within the region, or a false-negative cytogenetic diagnosis. However, discordance between prenatal and post-termination/postnatal cytogenetic findings was not observed in this series. The use of excess thymidine for induction of the fragile X in cultured CV cells provided in the majority of cases a safe and rapid method for cytogenetic diagnosis, with options for early induced termination in fragile-X-positive pregnancies, for simultaneous RFLP analysis, and for subsequent second-trimester analysis of fetal blood in complicated cases.

Adolescent↗
PubMed1991

Routine examination by ultrasound for the detection of fetal malformations in a low risk population.

A low risk population was offered screening for malformations in the second and third trimesters of pregnancy. Of 16,763 scans of pregnancies in the second trimester, 61 malformations were identified (0.36%). In the third trimester, scanning of 10,752 pregnancies revealed 24 malformations (0.22%): in all, in a low risk population 0.58% major malformations were found. The sensitivity for noncardiac malformations of the second trimester scanning was 54.3 with a specificity of 99.9%. The malformations overlooked was a more benign spectrum than the cases diagnosed. The sensitivity for cardiac malformations was less than 20%.

Congenital Abnormalities↗
PubMed1988

Dyssegmental dysplasia in siblings: prenatal ultrasonic diagnosis.

Two cases of dyssegmental dysplasia (type Silverman-Handmaker) in siblings are presented. The first-born died at the age of 3 months and the second fetus was followed during pregnancy with ultrasound examinations. In the 20th week of gestation marked shortening of the extremities was found; a female infant showing the same radiologic bony malformations as the firstborn was born by cesarean section. These cases support the autosomal recessive inheritance and demonstrate the possibility of prenatal diagnosis in this type of micromelic dwarfism.

Bone Diseases, Developmental↗
PubMed1987

Feto-maternal haemorrhage associated with genetic amniocentesis: results of a randomized trial.

Maternal serum alpha-fetoprotein (AFP) levels were determined before and after genetic amniocentesis (n = 283) or ultrasound scan (n = 268) in a group of women participating in a randomized trial of genetic amniocentesis. Increases in AFP levels were seen significantly more often after amniocentesis than after ultrasound scan (P less than 0.001) and 48 women in the amniocentesis group had increases in AFP (delta AFP) that were larger than the maximum delta AFP (+/- 25 micrograms/l) seen in the ultrasound group. If a delta AFP of greater than 25 micrograms/l represents a feto-maternal haemorrhage (FMH) attributable to amniocentesis, the rate of amniocentesis-induced FMH was 17%. Such FMH was seen significantly more often after transplacental amniocentesis or after amniocentesis performed by less experienced operators. No association was detected between birthweight and FMH attributable to amniocentesis.

Amniocentesis↗
PubMed1986

Randomised controlled trial of genetic amniocentesis in 4606 low-risk women.

Outcome of pregnancy after amniocentesis was studied in a randomised controlled trial of 4606 women, age-range 25-34 years, without known risk of genetic disease. Spontaneous abortion rate was 1.7% in the study group after amniocentesis and 0.7% in the control group after ultrasound (relative risk 2.3). In the study group, increased levels of maternal serum alpha-fetoprotein before amniocentesis, perforation of the placenta during amniocentesis, and withdrawal of discoloured amniotic fluid were associated with an increased risk of spontaneous abortion. In the first six weeks after amniocentesis/ultrasound scan, amniotic fluid leakage occurred more often in the study group but there was no difference in the rate of vaginal bleeding. Frequency of postural malformations in the infants in the two groups was the same. In the study group, respiratory distress syndrome was diagnosed more often (relative risk 2.1) and more babies were treated for pneumonia (relative risk 2.5).

Abortion, Spontaneous↗
PubMed1985

Maternal-serum-alphafetoprotein screening for fetal malformations in 28 062 pregnancies. A four-year experience from a low-risk area.

From 1st March, 1980 and up to 29th February 1984 a multicenter serum alpha-fetoprotein (S-AFP) screening project was carried out for the detection of severe fetal malformations. S-AFP was determined by a radio-immunoassay in 28 062 pregnant women between the 16th and 20th week of gestation. Patients with elevated S-AFP values, e.g. above 95 percentile, were examined further with a second S-AFP and by ultrasound scan. 244 amniocenteses (0.9%) were carried out to detect 62 malformations (21 anencephalies, 14 spina bifidas, 2 encephaloceles, 7 omphaloceles, 5 gastroschises, 4 chromosome abnormalities and 9 other malformations). Fifteen of the 16 cases of spina bifida could not be verified by ultrasound scan, whereas all other malformations except chromosome abnormalities were confirmed by ultrasonography. Two cases of spina bifida and one case of skin-covered encephalocele had normal S-AFP concentrations and were therefore not detected. There were no definitive false-positives, e.g. therapeutic abortion of a normal fetus. Our conclusion is that a nationwide S-AFP screening should be recommended.

Abdominal Muscles↗
PubMed1985

Successful ultrasound-guided intravascular transfusion in severe fetal anemia without blood group incompability.

A 26-year-old patient with chronic acquired pure red cell aplasia had given birth to two infants, both of which died from fetal hydrops and anemia. In her third pregnancy the fetus was diagnosed as being hydropic and anemic in the 24th gestational week. No blood group incompability could be demonstrated. Because of the low gestational age and presence of fetal ascites, intraperitoneal fetal blood transfusion was considered to be without effect, and three fetal intravascular transfusions were therefore performed in the 24th, 26th and 28th gestational weeks. The infant born in the 30th week, is in good health with a normal blood picture, 6 months later. Hydrops and fetal anemia has never been described as a complication of pregnancy in a patient with pure red cell aplasia and it is the first time that intrauterine intravascular fetal transfusion has been used other than for rhesus indication.

Adult↗