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Biomedical subjects

F M Cowan

Publications and source records attributed to F M Cowan.

At least 55 records · Page 3Linked to original sources
PubMed1998

Abnormal magnetic resonance signal in the internal capsule predicts poor neurodevelopmental outcome in infants with hypoxic-ischemic encephalopathy.

OBJECTIVE: The aim of this study was to establish whether abnormal signal intensity in the posterior limb of the internal capsule (PLIC) on magnetic resonance imaging is an accurate predictor of neurodevelopmental outcome at 1 year of age in infants with hypoxic-ischemic encephalopathy (HIE). METHODS: We have examined 73 term neonates with HIE between 1 and 17 days after birth with cranial magnetic resonance imaging and related the magnetic resonance imaging findings to neurodevelopmental outcome at 1 year of age. RESULTS: All infants with an abnormal signal intensity in the PLIC developed neurodevelopmental impairment although in 4 infants with very early scans the abnormal signal was not apparent until up to 4 days after birth. A normal signal intensity was associated with a normal outcome in all but 4 cases; 3 of these infants had minor impairments and all had persistent imaging changes within the white matter. The 4th infant with a normal signal intensity on day 2 died before a further image could be obtained. The absence of normal signal predicted abnormal outcome in term infants with HIE with a sensitivity of 0.90, a specificity of 1.0, a positive predictive value of 1.0, and a negative predictive value of 0.87. The test correctly predicted outcome in 93% of infants with grade II HIE, according to the Sarnat system. Applying a Bayesian approach, the predictive probability of the test (the probability that the test would predict an outcome correctly) was distributed with a mean of 0.94 and 95% confidence limits of 0.89 to 1.0. CONCLUSION: Abnormal signal intensity in the PLIC is an accurate predictor of neurodevelopmental outcome in term infants suffering HIE.

Basal Ganglia↗
PubMed1998

Magnetic resonance imaging of the neonatal brain.

Advances in magnetic resonance technology have revolutionized our ability to obtain detailed images of the neonatal brain without the use of ionizing radiation. Magnetic resonance imaging has now become the modality of choice for the in-vivo assessment of brain development, myelination and pathology.

Brain↗
PubMed1997

Cerebellar infarction and atrophy in infants and children with a history of premature birth.

BACKGROUND AND OBJECTIVE: We wished to determine the pattern of cerebellar disease in children with a history of premature birth and early ultrasound evidence of intraventricular haemorrhage and/or parenchymal lesions of the cerebral hemispheres. MATERIALS AND METHODS: MRI findings for all premature infants examined in a 3-year period (73 patients) were reviewed to determine the nature and frequency of lesions of the cerebellum and the results were correlated with clinical data. RESULTS: Six cases of unilateral cerebellar infarction were identified. These involved the posterior inferior cerebellar territory in each case (as well as other territories in two cases). A case of generalised cerebellar atrophy and three cases of unilateral cerebellar hemisphere atrophy were identified as well. In nine of these ten cases abnormalities were also seen elsewhere in the brain. CONCLUSION: The literature describes cerebellar infarction in infants and children as rare, but this study shows that it is not unusual following perinatal haemorrhagic/ischaemic anoxic injury. It is suggested that cerebellar atrophy may also occur as a result of vascular disease.

Arteries↗
PubMed1997

Does the brain regenerate after perinatal infarction?

We have used registered serial magnetic resonance scans to assess the growth of the brain after perinatal infarction in six infants. The initial scans were performed at ages of 4 days to 8 weeks and follow-up studies were performed from 4 days to 21 weeks later. A three-dimensional volume acquisition was performed on each occasion. Rigid body translations and rotations were used to match the images obtained on each occasion. Subtraction of the first image from the second then provided an assessment of the growth of the brain that had occurred between the two examinations. In the early phase of infarction (up to 2 months) low signal areas with clearly defined margins developed at the site of infarction. In the late phase (2 months onwards) growth was seen in the brain at the margins of the infarct in each case, and the size of the infarcted region showed a marked decrease in size. The rate of growth of the brain into the infarcted area exceeded that of the surrounding brain in some cases and was less in others. Growth of undamaged tissue may provide an important mechanism for recovery of the developing brain.

Brain↗
PubMed1997

Chiari I malformation in asymptomatic young children with Williams syndrome: clinical and MRI study.

We report clinical and magnetic resonance imaging findings in two young children, aged 2 years 4 months and 3 years, with Williams syndrome. Both showed a mild global delay, although their neurological examination was completely normal. Their magnetic resonance imaging, however, showed Chiari I malformation and some non-specific changes in the centrum semiovale and in the white matter posterior to the lateral ventricles. Cerebellar tonsils were displaced through the foramen magnum 8.5 and 7.5 mm respectively. Our results suggest that Chiari I malformation can also be a frequent feature in subjects with Williams syndrome even in the absence of overt neurological signs suggestive of it. Whether these children might develop acute signs later is not known at present. Further studies are needed not only to evaluate the incidence of these findings in the global population of subjects with Williams syndrome but also to identify the children who are at risk for developing acute neurological signs.

Arnold-Chiari Malformation↗
PubMed1997

Detection of subtle changes in the brains of infants and children via subvoxel registration and subtraction of serial MR images.

PURPOSE: To compare conventional two-dimensional multisection images with registered three-dimensional volume and subtraction images for detecting subtle changes in the brains of infants and children. METHODS: Twenty-six patients (24 with hemorrhagic/ischemic lesions) and one each with perinatal infection and Sturge-Weber disease were examined on two or more occasions with conventional multisection T1- and T2-weighted sequences as well as with 3-D T1-weighted volume sequences. A registration program was used to match the volume images to subvoxel dimensions, and subtracted images (second volume set minus the first) were obtained. The multisection images were compared with the 3-D and subtracted images and graded for detection of changes in a variety of brain structures. RESULTS: In 16% to 33% of comparisons of different structures, the multisection images and the 3-D registered and subtracted images showed changes equally well. The 3-D registered and subtracted images were better than the multisection images in 67% to 84% of comparisons for detection of changes in the cerebral hemispheres, ventricles, brain stem, cerebellum, and in lesions. Statistically significant differences were found between the graded performance of the registered 3-D images and the conventional 2-D images in detecting cerebral infarction and hypoxic ischemic encephalopathy. In the late phase following neonatal cerebral infarction (1 to 11 months), the 3-D registered and subtracted images revealed growth of the brain at the margins of the lesions. CONCLUSION: Subvoxel registration of serial MR images may be of value in detecting subtle changes in the brains of infants and children.

Brain↗
PubMed1996

Behavioural risk factors for HIV infection amongst blood donors in London.

This paper compares the prevalence of risk factors for sexual acquisition of human immunodeficiency virus infection (HIV-1) among blood donors with the risk in the general population. Sexual behaviour data collected as part of a cross-sectional survey of central London blood donors were compared, after indirect standardization for age and sex, with those collected among Greater London participants of the National Survey of Sexual Attitudes and Lifestyles (NATSSAL). Overall, male blood donors had lower risk sexual lifestyles than age-matched NATSSAL participants in that they had had fewer lifetime female sexual partners, were more likely to have had first sexual intercourse after 16 years and were less likely to have had a homosexual partner. Men who have had sex with men since 1977 were asked not to donate blood. Despite this, 3.6% of male donors had had some sexual experience with another man and 1.9% had had sexual intercourse with at least one male partner. In contrast, female donors had had more sexual partners, were more likely to have had first sexual intercourse before 16 years and had probable higher rates of sexually transmitted disease (STD) clinic attendance than NATSSAL participants, explained by the much higher proportion of single rather than married female blood donors at each age. In conclusion, male donors had lower risk sexual lifestyles than age-matched NATSSAL participants, although even low levels of homosexual contact give some cause for concern. Female donors appeared to have higher risk sexual lifestyles than the general population because a much higher proportion of the female blood donors were single. The results provide important insights for those defining blood donor referral criteria.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Relationship between antibodies to herpes simplex virus (HSV) and symptoms of HSV infection.

To determine the relationship between antibodies to herpes simplex virus (HSV) types 1 and 2 and diagnosis of orolabial and genital herpes, a cross-sectional survey was done among 869 sexually transmitted disease clinic attendees and 1594 blood donors in London. Among clinic attenders, the prevalence of HSV-1 infection was 59.5% and that of HSV-2 infection was 22.7%, and among blood donors the prevalence was 44.6% and 7.6%, respectively. The sensitivity and specificity of a diagnosis of oral herpes for the presence of HSV-1 antibody was almost identical in the 2 groups (clinic attendees: sensitivity, 33.1%, and specificity, 91.4%; blood donors: sensitivity, 32.3%, and specificity, 94.3%). A diagnosis of genital herpes was less sensitive for antibody for HSV-2 among donors than among clinic attenders (P < .001); however, the specificity was similar in the 2 populations (clinic attendees: sensitivity, 32.1%, and specificity, 96.6%; blood donors: sensitivity, 17.5%, and specificity, 99.5%). False-positive clinical histories were also relatively common (clinic attenders, 12%; donors, 6%). The sensitivity of the diagnosis of genital herpes would be improved if accurate serologic assays for detection of HSV type-specific antibodies were more widely available.

Antibodies, Viral↗
PubMed1996

Cerebral metabolism within 18 hours of birth asphyxia: a proton magnetic resonance spectroscopy study.

Proton magnetic resonance spectroscopy (1H MRS) was performed within 18 h of birth (median 13, range 4-18 h) on 16 term infants with clinical features of birth asphyxia. Ten infants with no evidence of birth asphyxia were studied as controls at 5-18 (median 8) h after birth. To detect delayed impairments in cerebral energy metabolism, 15 infants suspected of asphyxia underwent 31P MRS at 33-106 (median 62) h of age. Choline, creatine, and N-acetylaspartate (NAA) were detected in spectra located to the basal ganglia in all infants. Lactate was detected in 15 of the 16 infants suspected of asphyxia, but in only 4 of the 10 controls (p < 0.05, chi 2). Glutamine and glutamate (Glx) was detected in 11 infants suspected of asphyxia and in three controls, but this difference was not significant at the 5% level. The spectra revealed no other significant differences between asphyxiated infants and controls. In the asphyxiated infants, there was a negative correlation between the ratio of lactate to creatine in the first 18 h of life and phosphocreatine/inorganic phosphate (PCr/ P(i)) at 33-106 h (p < 0.001). Five severely asphyxiated infants had PCr/P(i) < 0.75 (median 0.53, range 0.14-0.65), indicating a poor neurodevelopmental prognosis, and a further infant died before PCr/Pi could be measured. Ten infants had PCr/P(i) > 0.75 (1.03, 0.76-1.49). Median lactate/creatine was 1.47 (range 0.67-3.81) in the six severely affected subjects, 0.38 (0-1.51) in the latter group, and 0 (0-0.6) in controls (p < 0.0005, Kruskall-Wallis). These results suggest that, after birth asphyxia, cerebral energy metabolism is abnormal during the period when 31P MRS characteristically gives normal results. 1H MRS might be of value in predicting which infants are likely to suffer a decline in cerebral high energy phosphate concentrations and subsequent neurodevelopmental impairment.

Asphyxia Neonatorum↗
PubMed1995

Monoclonal antibody blocking tests for the detection of HSV-1- and HSV-2-specific humoral responses: comparison with western blot assay.

Monoclonal antibody blocking radioimmunoassays (MAb block RIAs) which detect specific humoral responses to each of the two human herpes simplex virus (HSV) types are described. RIAs were compared with Western blot assay (WBA) in a blind study of 64 sera obtained from clinically well-documented cases of genital herpes. WBA and MAb block RIA each detected HSV-1 antibodies in 16/17 (94%) sera from confirmed HSV-1 genital infections (first episodes and recurrent infections). Detection of HSV-2 antibody in 21 sera from HSV-2 first episodes was more effective by WBA which identified homologous antibody in 19 (96%), whereas MAb block RIA detected HSV-2 antibody in 16 (76%). HSV-2 antibody was detected in 24/25 (96%) sera from recurrent HSV-2 infections by WBA and by MAb block RIA, the highest degree of concordance for both methods. In addition, the MAb block RIA may be more effective in detecting the presence of HSV-1 antibody in sera from recurrent HSV-2 cases. Prevalence of HSV-1 and HSV-2 antibody was measured by the MAb block RIAs in 3 UK human study populations which consisted of 100 children/young adolescents, 104 adult blood donors and 80 genito-urinary medicine clinic attenders.

Adolescent↗
PubMed1995

Hypoxic ischaemic encephalopathy: early magnetic resonance imaging findings and their evolution.

Eighteen term infants with hypoxic ischaemic encephalopathy (HIE) were studied with serial magnetic resonance imaging of the brain for up to two months following birth. Important early findings included brain swelling, cortical highlighting, diffuse loss of grey/white differentiation and loss of signal in the posterior limb of the internal capsule (PLIC). These signs were easier to identify on T1-weighted spin echo or inversion recovery sequences than on T2-weighted spin echo sequences. Brain swelling was only seen in the first seven days and was present in all grades of HIE. All other signs persisted and were associated with the subsequent development of major structural changes in the brain. The exact pattern of injury was best identified after the first week of life once the signs of brain swelling had cleared.

Asphyxia Neonatorum↗
PubMed1994

Antibody to herpes simplex virus type 2 as serological marker of sexual lifestyle in populations.

OBJECTIVES: To examine the epidemiology of antibody to herpes simplex virus type 2 and to assess its suitability as a serological marker of sexual behaviour in populations with high and low prevalences. DESIGN: Cross sectional survey. SETTING: Department of genitourinary medicine and blood donation centre in central London. SUBJECTS: Representative sample of 869 patients attending department between November 1990 and December 1991, and 1494 consecutive blood donors attending for donation between February and April 1992. METHOD: Participants had a blood sample taken for antibody testing with a novel type specific assay and completed a questionnaire. RESULTS: Prevalence of antibody differed significantly between the two groups (188/833 (22.7%) clinic attenders; 102/1347 (7.6%) blood donors). In both populations antibody was strongly associated with sex, sexual orientation, years of sexual activity, number of lifetime sexual partners, and past infection with sexually transmitted diseases after other factors were controlled for. Only 130 (45%) of all those with antibody had symptoms suggestive of genital herpes, and 79 (27.4%) had had genital herpes diagnosed. Of those without antibody to herpes simplex viruses type 1 and 2, 8.0% reported genital blisters or sores and 1.1% had had genital herpes diagnosed by a doctor. CONCLUSIONS: The strong relation between herpes simplex virus type 2 and sexual lifestyle suggests that the presence of antibody to the virus may be suitable for use as an objective, serological marker of patterns of sexual behaviour in different populations. These data show that only a minority of those infected with herpes simplex virus type 2 have a diagnosis of genital herpes or express clinical symptoms, making serological determinants of infection essential for epidemiological studies.

Adolescent↗