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Biomedical subjects

W Thompson

Publications and source records attributed to W Thompson.

At least 19 recordsLinked to original sources
PubMed1992

The use of transcranial ultrasonography to predict stroke in sickle cell disease.

BACKGROUND: Stroke, especially cerebral infarction, is a major cause of morbidity and mortality in children with sickle cell disease. Primary prevention of stroke by transfusion therapy may be feasible if there is a way to identify the patients at greatest risk. Transcranial Doppler ultrasonography can measure flow velocity in the large intracranial arteries. The narrowing of these arteries, which leads to cerebral infarction, is characterized by an increased velocity of flow. METHODS: Using transcranial Doppler ultrasonography, we prospectively measured the velocity of cerebral blood flow in children and young adults being followed because of sickle cell disease. The results were classified as either normal or abnormal on the basis of the highest velocity of flow in the middle cerebral artery. Abnormal velocity was defined as a flow greater than or equal to 170 cm per second, a definition determined by post hoc analysis to maximize the predictive success of the test. The end point was a clinically apparent first cerebral infarction. RESULTS: Two hundred eighty-three transcranial ultrasound examinations were performed in 190 patients with sickle cell disease (age at entry, 3 to 18 years). After an average follow-up of 29 months, cerebral infarction was diagnosed in seven patients. In 23 patients the results of the ultrasound examinations were abnormal, and in 167 patients they were normal. The clinical and hematologic characteristics of the two groups were similar, but six of the seven strokes occurred among the 23 patients with abnormal ultrasound results (P less than 0.00001 by Fisher's exact test). In this group, the relative risk of stroke was 44 (95 percent confidence interval, 5.5 to 346). CONCLUSIONS: Transcranial ultrasonography can identify the children with sickle cell disease who are at highest risk for cerebral infarction. Periodic ultrasound examinations and the selective use of transfusion therapy could make the primary prevention of stroke an achievable goal.

Adolescent↗
PubMed1992

Transperineal percutaneous iridium-192 interstitial template implant of the prostate: results and complications in 321 patients.

A total of 321 patients with localized adenocarcinoma of the prostate treated by modified pelvic lymphadenectomy, Iridium-192 implant, and external beam iridium radiation were retrospectively reviewed. Analysis covered 8 years between 1981 and 1989 with a median population age of 72 (range 42 through 82 years). Disease-free survival for the entire group is 69% at 5 years with a median follow-up of 34 months (range 1.5 months to 98.5 months). As expected, both bulkier disease and positive nodal status adversely affected 5-year disease-free survival (p = 0.0001 for both). For tumors stage T1b (A2), T2a (B1), T2b (B2), T3 (C) the disease-free survival is 89.5%, 89.9%, 64.7%, and 48.8%, respectively; for NO disease 5-year disease-free survival is 76.5% versus N1/N2 disease with 5-year disease-free survival of 33.2%. Local control was excellent except for bulkier disease (p = 0.009). Tumors T1b, T2a, T2b, and T3 have 60-month local control rates of 95%, 93%, 83.6%, and 73.1%, respectively. Histologic grade also affected disease-free survival and local control with grade 1, grade 2, grade 3 showing 81.2%, 65.7%, and 45.1% disease-free survival at 5 years; and 93.6%, 82.2%, and 72.4% local control at 5 years. Estimates obtained using Kaplan-Meier method. Radiation induced morbidity was analyzed separately for all patients, there were 41 patients (13% of total) with 54 documented complications. There were no Grade 4 or 5 complications as per RTOG categories. Only 3 cases showed grade 3 complications (1%) and 51 cases showed grade 2 complications (15.9%). Grade 1 complications were not recorded. Of the grade 2 and grade 3 complications 30 were GU and 22 were rectal. The morbidity associated with combined interstitial implantation by transperineal percutaneous template and external beam iridium radiation for the localized prostate cancer is minimal with excellent local control and disease-free survival.

Adenocarcinoma↗
PubMed1992

Role of endotoxin in alterations of hepatic drug metabolism by diphtheria and tetanus toxoids and pertussis vaccine adsorbed.

Administration of diphtheria and tetanus toxoids and pertussis vaccine adsorbed (DTP vaccine) or endotoxin (LPS) resulted in marked alterations in hepatic drug-metabolizing enzymes in endotoxin-responsive (R) and non-endotoxin-responsive (NR) mice. A single human dose (0.5 ml) of DTP vaccine increased hexobarbital-induced sleep times to 1.6- to 1.8-fold above those of controls in both strains of mice. This effect persisted for 7 days. In contrast, Bordetella pertussis LPS-treated mice showed an increase at 1 day (3.0-fold for R mice and 1.5-fold for NR mice), which returned to control levels by day 7. Furthermore, cytochrome P-450 levels were decreased 30 to 40% 24 h after DTP vaccine administration in both R and NR mice, while after LPS administration they were decreased 30% in R mice and less than 10% in NR mice. Both spleen and liver weights of R and NR mice were increased 7 to 14 days following DTP vaccine administration. However, LPS treatment had no apparent effect on liver weights, and spleen weights of R mice were elevated from days 3 to 7. Histopathologic tissue examination showed random, multifocal inflammation with hepatocyte necrosis after DTP vaccine administration to both R and NR mice and an absence of lesions in LPS-treated mice. Premixing LPS with polymyxin eliminated the increased sleep times, but premixing DTP vaccine with polymyxin did not affect the increased sleep times. Levels of tumor necrosis factor and interleukin-6 in plasma of R mice were markedly increased after DTP and LPS treatment, while NR mice had reduced increases. These results suggest that LPS contributes to the alterations in R and NR mice seen within the first 24 h of vaccine administration but that it is not likely to contribute to the effects observed at later time points.

Animals↗
PubMed1992

Vasopressor therapy for hypotension during epidural anesthesia for cesarean section: effects on maternal and fetal flow velocity ratios.

The purpose of this study was to identify the influence of hypotension as a result of epidural anesthesia and of its treatment with either ephedrine or methoxamine on uteroplacental and umbilical flow velocity ratios and fetal acid-base status. Fifty healthy women with an uncomplicated full-term pregnancy were studied during elective cesarean section under epidural anesthesia. A method of continuously recording flow velocity waveforms was used that allowed the identification of simultaneous values of maternal and fetal Doppler indices related to events during the induction of anesthesia. In 15 patients in whom arterial blood pressure did not decrease, the uteroplacental pulsatility index (UtPI) did not change, but the umbilical pulsatility index (UmPI) decreased from a mean (95% confidence interval) of 0.98 (0.88-1.09) to 0.91 (0.82-0.99) (P less than 0.05). In 32 patients who experienced hypotension of at least 15%, the UtPI increased from 0.82 (0.76-0.89) to 1.04 (0.92-1.17) (P less than 0.01). Treatment with ephedrine had no influence on either the UtPI or UmPI, but treatment with methoxamine resulted in brief increases in the UtPI of 0.47 (0.24-0.69) during the first 5 min after its administration; the increases were brief and resolved within 2 min. The choice of vasopressor drug had no influence on the UtPI recorded just before surgery commenced (final UtPI), but those patients who experienced hypotension had significantly larger final UtPIs (1.02 (0.91-1.10)) than those who never became hypotensive (0.86 (0.72-0.99)), and this was associated with significantly increased placental hydrogen ion gradients. The choice of vasopressor drug appears to be of minor importance compared with the avoidance of hypotension.

Adult↗
PubMed1991

Evidence of Chlamydia infection in a Belfast antenatal population.

Chlamydia trachomatis is an important cause of postpartum endometritis and neonatal conjunctivitis. However, the prevalence of chlamydial genital infection varies considerably from one population group to another. A study was thus conducted to determine the incidence of C trachomatis infection of the cervix in an unselected group of women attending a Belfast antenatal clinic. One hundred and six patients were screened for evidence of current cervical infection with C trachomatis or serological evidence of past infection. C trachomatis was identified in 2.9%, and there was evidence of past infection in 18.9%. No significant risk factors were identified from gynaecological, contraceptive or sexual histories. C trachomatis infection was treated with erythromycin and there were no perinatal complications ascribed to chlamydia.

Adult↗
PubMed1979

Prenatal diagnosis of the Meckel syndrome.

Prenatal diagnosis of the Meckel syndrome was made at 20 weeks of gestation from the findings of a biparietal diameter smaller than expected for gestational age, a grossly raised amniotic fluid alphafetoprotein level and a rapid growth of foetal macrophages after 20 hours culture. Termination at 23 weeks of gestation resulted in a male foetus with an occipital encephalocele, microcephaly, polydactyly, and bilateral polycystic kidneys. This case report emphasies the importance for genetic counselling of delineating the Meckel syndrome from the multifactorial cases of neural tube defects, and also illustrates, at least in some cases, that the syndrome can be diagnosed in utero.

Abnormalities, Multiple↗
PubMed1979

The effects of post-ganglionic axotomy on selective synaptic connexions in the superior cervical ganglion of the guinea-pig.

Stimulation of preganglionic axons arising from different levels of the thoracic spinal cord causes different effects on end-organs supplied by the superior cervical ganglion (Langley, 1892; Nja & Purves, 1977a; Lichtman, Purves & Yip, 1979). For example, stimulation of the first thoracic ventral root (T1) causes pupillary dilatation and widening of the palpebral fissure; stimulation of T4, on the other hand, has little effect on the eye, even though axons arising from this level innervate about as many superior cervical ganglion cells as those from T1. Thus ganglion cell innervation is selective. (1) Three months after crushing the major post-ganglionic branches of the superior cervical ganglion this differential effectiveness is lost: T1 and T4 stimulation have approximately equal effects on the end-organs of the eye. (2) In normal animals, the cellular counterpart of selective end-organ effects is the innervation of each ganglion cell by a contiguous subset of the spinal segments that innervate the ganglion as a whole. One of these segments is usually dominant, the strength of innervation from adjacent segments falling off as a function of distance from the dominant one (Nja & Purves, 1977a). Intracellular recordings from ganglion cells 3 months after post-ganglionic axotomy showed that this selective pattern is re-established. (3) Since the innervation of ganglion cells appears normal, the abnormal end-organ responses after post-ganglionic axotomy suggest that ganglion cell axons are not limited to their original targets during peripheral re-innervation. This suggestion is supported by the finding that ganglion cells sending axons to different peripheral destinations via the second and third cervical spinal nerves were no longer distinguishable on the basis of their segmented inputs 3 months after post-ganglionic axotomy. (4) Similar results were obtained when the preganglionic cervical trunk was cut at the same time as the post-ganglionic axons were crushed; the pattern of end-organ responses was abnormal, whereas individual ganglion cells were re-innervated according to the rules of contiguity and segmental dominance. (5) These results indicate that ganglion cells do not undergo a compensatory change in the segmental innervation they receive when their axons regenerate to targets different from, or in addition to those they originally innervated, even when an entirely new set of ganglionic connexions is formed. This suggests that ganglion cells, or some aspect of their immediate environment, possess a permanent label that determines the segmental innervation they receive.

Animals↗
PubMed1979

Trisomy 20 mosaicism in amniotic fluid cell culture.

Chromosomal mosaicism in cultured amniotic fluid cells presents one of the most difficult problems in prenatal diagnosis in predicting the foetal phenotype. We present a case in which trisomy 20 mosaicism was diagnosed prenatally but not confirmed in the aborted foetus.

Abortion, Induced↗
PubMed1978

A randomized controlled trial of selective planned delivery.

A prospective randomized controlled trial designed to investigate selective planned delivery is reported: 264 obstetrically normal women in the 38th week of pregnancy were admitted to this trial and 184 completed it. The infants of mothers in the planned delivery group had higher serum bilirubin levels on the fifth day post partum than control infants but no baby required treatment for hyperbilirubinaemia. Mothers in the planned delivery group required significantly greater amounts of pethidine while control mothers had a significantly higher incidence of meconium staining of the amniotic fluid. However, the infants in the two groups had similar Apgar scores at birth. There was one stillbirth in the control group; this was due to unrecognized fetal hypoxia during labour induced at 42 weeks for postmaturity.

Apgar Score↗