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Biomedical subjects

A Billett

Publications and source records attributed to A Billett.

5 recordsLinked to original sources
PubMed2001

Antiangiogenesis therapy. Current and future agents.

Approaches to cancer therapy for most tumors in adults and children have changed little in 50 years: surgery, radiation, and chemotherapy are standard for many solid tumors. When the concept of angiogenesis in cancer biology was introduced in the 1970s, there was little recognition of the therapeutic potential of attacking a tumor's blood supply. Advances in understanding the molecular processes that regulate tumor blood supply and novel agents that can interfere with them have generated a great deal of scientific interest and excitement. This article reviews the current understanding of angiogenesis and its role in cancer then discusses new therapeutic options in animals and humans, with a focus on pediatric tumors and the potential for treating them.

Angiogenesis Inhibitors↗
PubMed1998

Obstetric outcome in 232 ovum donation pregnancies.

OBJECTIVE: To study the obstetric outcome of ovum donation pregnancies. DESIGN: A retrospective analysis of 232 ovum donation pregnancies in the six years from 1988 to 1993. SETTING: Infertility clinic in a private hospital. PARTICIPANTS: All ovum donation recipients that achieved pregnancy in the clinic during the stated time period. MAIN OUTCOME MEASURES: Percentages of live birth and miscarriages and ectopic pregnancies; number of sacs identified in the uterus at early (four weeks after transfer) and later scans; incidence of antepartum and postpartum haemorrhage; incidence of pregnancy-induced hypertension; incidence of preterm, low birthweight and small-for-gestational age babies; and incidence of operative deliveries. RESULTS: Of 232 pregnancies, 151 babies were born (live birth rate of 20%); and 81 were lost (57 before eight weeks, 17 after eight weeks and seven ectopic pregnancies). In nine cases there were no intrauterine sacs at the early scan (two 'chemical pregnancies' and seven ectopic pregnancies). In 169 cases there was initially one intrauterine sac, ending with 102 singleton deliveries (60%); in 47 cases there were initially two intrauterine sacs, ending with 11 singleton deliveries (23%) and 32 twin deliveries (68%); in the seven cases where three sacs were identified initially, there were no singleton deliveries, three twin deliveries (one selective fetal reduction) and three triplet deliveries. Women with premature ovarian failures had a significantly higher pregnancy rate compared with those with functioning ovaries (P < 0.02). However, in the former group, the miscarriage rate was also significantly higher (P < 0.03) so that the number of term births was similar. The incidence of vaginal bleeding was 12% in the first trimester, 1.5% in the second trimester, and 2% in the third trimester. The incidence of postpartum haemorrhage was 12%. Thirty-two women had pregnancy-induced hypertension (23% of all deliveries). This occurred in 22/105 singletons (21%), 7/32 twins (22%) and in all three (100%) of the triplets. In the singleton group 13% of infants were preterm, 18% had a birthweight < 2.5 kg and 15% were < 3rd centile for birthweight at delivery (small-for-gestational age). Ovarian function was found to be the only factor that significantly influenced the incidence of small-for-gestational age babies (odds ratio 8.84; 95% confidence interval 1.1-70.0; P = 0.007). The overall operative delivery rate was 85% with the caesarean section rate being 69%. CONCLUSIONS: Women who become pregnant following oocyte donation should be considered obstetrically as high risk, especially those with ovarian failure because of the increased incidence of small-for-gestational age infants in these pregnancies. They are also at higher risk of pregnancy-induced hypertension and postpartum haemorrhage.

Abortion, Spontaneous↗
PubMed1996

Magnetic resonance imaging changes after stereotactic radiation therapy for childhood low grade astrocytoma.

BACKGROUND: Stereotactic radiotherapy (SRT) is fractionated radiotherapy delivered under stereotactic guidance to produce highly focal and precise therapy. We studied the incidence of imaging changes that can mimic tumor progression after completion of SRT for childhood low grade astrocytoma. METHODS: Between June 1992 and September 1994, we prospectively treated 28 children with low grade astrocytomas with SRT. The patients ranged in age from 2 to 22 years (median: 10 yrs) and none had received prior radiation therapy or radiosurgery. Routine fractionation was employed (180-200 centigray[cGy]) to a total dose of 5220-6000 cGy over 5 to 6 weeks. All of the patients underwent initial and follow-up magnetic resonance imaging (MRI) according to protocol. RESULTS: Median clinical follow-up for the 28 patients was 24 months (range, 5-32 mos) with a median radiographic follow-up of 15 months (range, 3-26 mos). Fifteen patients had reduction in tumor size, one patient had stable disease. Twelve patients (43%) developed increased size of the lesion, increased signal intensity or enhancement, cysts or cavitations, and an increase in edema or mass effect on follow-up MRI. Most of these changes occurred between 9 and 12 months after the start of SRT and resolved or decreased by 15 to 21 months. All but one patient had normal or stable neurologic examinations. CONCLUSIONS: Treatment-related MRI changes are common after conventionally fractionated schedules using stereotactic radiation techniques for patients with low grade astrocytomas. These changes can be distinguished from tumor progression by their transient nature as well as the general absence of clinical symptoms.

Adolescent↗
PubMed1994

Advances in radiation therapy for craniopharyngiomas.

The overall survival for patients with craniopharyngioma is excellent. However, conventional treatments that include aggressive surgery and standard irradiation have been associated with significant morbidity. Focal radiation treatment with stereotactic radiosurgery has a role in selected cases, but may also be damaging to sensitive normal tissues such as the optic chiasm. Stereotactic radiotherapy (SRT) is a technique that allows for conventionally fractionated radiation under stereotactic guidance. Thus, highly focal and precise radiotherapy is now coupled with fractionation, enabling the treatment of selected tumors with a potentially improved therapeutic index. Dose optimization with SRT for focally discrete tumors should result in equivalent local control and survival compared to patients treated with conventional irradiation. We anticipate a significant decrease in late effects, especially neuropsychological and neuroendocrine sequelae.

Child↗