PubMed Health⌕ Search

Biomedical subjects

F Brook

Publications and source records attributed to F Brook.

12 recordsLinked to original sources
PubMed2004

Prediction from ultrasonographic measurements of the expected delivery date in two species of bottlenosed dolphin (Tursiops truncatus and Tursiops aduncus).

Ultrasonographic measurements were made at least once a month during 14 gestations in seven Tursiops truncatus and 12 gestations in five Tursiops aduncus (bottlenosed dolphins). The 121 measurements of the fetal biparietal diameter and 139 measurements of the fetal thoracic diameter in T truncatus and the 97 measurements of the biparietal diameter and 97 measurements of the thoracic diameter in Taduncus were used to establish regression lines for the increases in the diameter of the head and thorax of the fetus with time. From these relationships an easy-to-use computer program was developed to predict the date of birth of the two species of bottlenosed dolphin, and its predictions were compared with the actual dates of birth of other calves of both species. The births occurred within the range of predicted dates, and even when only a few measurements were available, the program provided accurate predictions.

Animals↗
PubMed2001

Vascularity and grey-scale sonographic features of normal cervical lymph nodes: variations with nodal size.

AIM: This study was undertaken to investigate variations in the vascularity and grey-scale sonographic features of cervical lymph nodes with their size. MATERIALS AND METHODS: High resolution grey-scale sonography and power Doppler sonography were performed in 1133 cervical nodes in 109 volunteers who had a sonographic examination of the neck. Standardized parameters were used in power Doppler sonography. RESULTS: About 90% of lymph nodes with a maximum transverse diameter greater than 5 mm showed vascularity and an echogenic hilus. Smaller nodes were less likely to show vascularity and an echogenic hilus. As the size of the lymph nodes increased, the intranodal blood flow velocity increased significantly (P < 0.05), whereas there was no significant variation in the vascular resistance(P> 0.05). CONCLUSIONS: The findings provide a baseline for grey-scale and power Doppler sonography of normal cervical lymph nodes. Sonologists will find varying vascularity and grey-scale appearances when encountering nodes of different sizes.Ying, M.et al. (2001). Clinical Radiology, 56, 416-419.

Adult↗
PubMed2001

Effect of gonadotrophins on the ovarian interstitial tissue of the wood mouse, Apodemus sylvaticus.

The ovarian interstitial tissue of the wood mouse (Apodemus sylvaticus) is extensively developed. The effect of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) on ovarian interstitial tissue was investigated in wood mice from a laboratory stock. The tissue was assessed by measuring the relative size of the cells, cell nucleus diameter and (in adults) nuclear shape. Hormone-treated wood mice had larger interstitial cells and larger cell nuclei than untreated animals. In addition, the cell nuclei of adult hormone-treated wood mice had a smooth round or oval outline, whereas those of untreated animals had an irregular outline with spiky projections. Electron microscopy showed that the irregular spiky outline of the cell nuclei in untreated wood mice was caused by distortions of the nuclear membrane by a large number of intracellular lipid droplets; the droplets were less abundant in the hormone-treated animals. These experiments indicate that the cells of the interstitial tissue of the wood mouse are under the control of gonadotrophins, and that these cells are likely to be a site of the synthesis and release of steroid hormones. The methods used in this study to assess the state of the cells could be applied to animals from the field to investigate the role of interstitial tissue in the reproductive biology of wood mice.

Aging↗
PubMed2000

A structurally defined mini-chromosome vector for the mouse germ line.

Yeast artificial mini-chromosomes have helped to define the features of chromosome architecture important for accurate segregation and replication and have been used to identify genes important for chromosome stability and as large-fragment cloning vectors. Artificial chromosomes have been developed in human cells but they do not have defined, experimentally predictable structures. Fragments of human chromosomes have also been introduced into mice and in one case passed through the germ line. In these experiments, however, the structure and sequence organization of the fragments was not defined. Structurally defined mammalian mini-chromosome vectors should allow large tracts of DNA to be introduced into the vertebrate germ line for biotechnological purposes and for investigations of features of chromosome structure that influence gene expression. Here, we have determined the structure and sequence organization of an engineered mammalian mini-chromosome, ST1, and shown that it is stably maintained in vertebrate somatic cells and that it can be transmitted through the mouse germ line.

Animals↗
PubMed2000

Power Doppler sonography of normal cervical lymph nodes.

This study was undertaken to investigate the vascular patterns and resistance of normal cervical nodes by power Doppler sonography. In 101 subjects who had a sonographic examination of the neck, 1050 lymph nodes were detected. Only central vascularity was found in normal cervical nodes. The degree of vascularity in submental and submandibular nodes was higher than that in other regional nodes. Submental nodes had a higher vascular resistance in association with a lower blood flow velocity than other regional nodes. No significant difference was found in blood flow velocities and vascular resistance between male and female subjects. The vascular resistance increased significantly with age. This study provides a baseline for vascularity within normal cervical nodes, as seen by power Doppler sonography.

Adult↗
PubMed1999

Relationship of thyroid blood flow to reproductive events in normal Chinese females.

The purpose of this study was to investigate the blood flow characteristics in the superior thyroid artery (STA) in normal females of prepubertal, reproductive, and postmenopausal age. The study was performed in 29 prepubertal girls, 27 females of reproductive age, and 26 postmenopausal women. The peak systolic velocity (PSV) and the pulsatility index (PI) of the STA were measured repeatedly during one menstrual cycle in females of reproductive age, and measured once in each prepubertal and postmenopausal subject. Different waveforms were observed in females of prepubertal, reproductive, and postmenopausal age. The PSV of the STA increased progressively in females from prepubertal to postmenopausal phases. The PI of the STA in all of the prepubertal girls was lower than that of adult females in different phases of the menstrual cycle. In adult females, the PI in the follicular phase was significantly higher than those in the ovulatory and luteal phases. In all of the postmenopausal women, the PI was comparable to that in older prepubertal subjects and in adult females during the ovulatory and luteal phases. The results suggest that oestrogen may affect thyroid blood flow during the normal menstrual cycle. Growth and progressive change of arterial structure are suggested to affect the thyroid blood flow in prepubertal and postmenopausal states.

Adult↗
PubMed1999

Nodal shape (S/L) and its combination with size for assessment of cervical lymphadenopathy: which cut-off should be used?

The short axis to long axis (S/L) ratio is commonly used to assess cervical lymphadenopathy; however, the cut-off value used has been limited to 0.5. The accuracy of the combination of S/L ratio and nodal size has not been documented previously. We evaluated 1143 normal cervical nodes from 95 healthy subjects, and 1441 nodes from 290 patients with proven cervical lymphadenopathy. The optimum cut-off value of the S/L ratio was determined in different regions of the neck: submental (0.5), submandibular (0.7), parotid (0.5), upper cervical (0.4), middle cervical (0.3) and posterior triangle (0.4). In the submandibular and parotid regions, the combination of the S/L ratio and short axis shows substantial improvement in diagnostic accuracy when compared to the S/L ratio alone.

Adolescent↗
PubMed1998

Alteration of thyroid blood flow during the normal menstrual cycle in healthy Chinese women.

The purpose of this study was to investigate the relationship between thyroid activity and the menstrual cycle by measuring the Doppler parameters of the superior thyroid arteries in women of reproductive age. The study was performed in 27 healthy Chinese women aged between 19 and 28 y for one menstrual cycle, and 25 age-matched healthy Chinese men for 3 weeks for comparison. In women, the peak systolic velocity increased from the follicular phase to the luteal phase, and the pulsatility index decreased from the follicular phase to the ovulatory phase and increased slightly in the luteal phase. In men, alterations in the pattern of thyroid blood flow were not observed; however, the average values of Doppler parameters during the study period in women were similar to those in men. The gender difference in the pattern of flow characteristics in the superior thyroid artery suggests effects of estrogen on thyroid function.

Adolescent↗
PubMed1998

The value of thyroid parenchymal echogenicity as an indicator of pathology using the sternomastoid muscle for comparison.

This study was undertaken to evaluate the diagnostic accuracy of comparison of the echogenicity of the thyroid gland with the sternomastoid muscle in diagnosis of thyroid disorders. Fifty healthy subjects underwent a thyroid ultrasound, and 80 patients with archived thyroid ultrasound examinations (50 thyrotoxicosis and 30 thyroiditis) were reviewed. Images were measured for the image density of the thyroid gland and the sternomastoid muscle, using a transmission densitometer. Healthy thyroid was relatively hyperechoic when compared with the sternomastoid muscle (100%). Of the thyrotoxic patients, 70% showed a relatively hyperechoic thyroid compared to 47% of the thyroiditis patients. Mean image density difference in healthy thyroid, thyrotoxicosis and thyroiditis ranged from 0.1 to 1, -0.42 to 0.83, and -0.55 to 0.58, respectively. In conclusion, the relative echogenicity of the thyroid gland when compared with the sternomastoid muscle may be useful to differentiate healthy thyroid from thyrotoxicosis and thyroiditis, but does not help to distinguish thyrotoxicosis from thyroiditis. An image density difference of less than 0.1 may be considered to be abnormal, whereas a value greater than 0.83 may be considered to be normal.

Adolescent↗
PubMed1996

Sonographic appearance and distribution of normal cervical lymph nodes in a Chinese population.

In 100 normal subjects who had a sonographic examination of the neck, 1211 lymph nodes were detected. In all the subjects, at least five lymph nodes were seen. The distribution, number, echogenicity, shape, presence or absence of echogenic hilus, and the sharpness of nodal borders of normal cervical lymph nodes were determined. The usefulness of these sonographic features in understanding the normal distribution and characteristics of the nodes in the Chinese population is discussed. The relationship between the shape and size of lymph node also was assessed.

Adolescent↗
PubMedDate not supplied

Sonographic appearance of craniofacial dysostosis in utero.

Crouzon's syndrome, or craniofacial dysostosis, is a rare congenital abnormality which may be associated with life-threatening conditions, such as congenital heart defects. The effects of the premature synostosis and some of the facial abnormalities can be detected antenatally with ultrasound and thus provide the paediatrician with a useful 'early warning system'.

Adult↗