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B Brown

Publications and source records attributed to B Brown.

At least 73 records · Page 4Linked to original sources
PubMed1999

Equatorius: a new hominoid genus from the Middle Miocene of Kenya.

A partial hominoid skeleton just older than 15 million years from sediments in the Tugen Hills of north central Kenya mandates a revision of the hominoid genus Kenyapithecus, a possible early member of the great ape-human clade. The Tugen Hills specimen represents a new genus, which also incorporates all material previously referable to Kenyapithecus africanus. The new taxon is derived with respect to earlier Miocene hominoids but is primitive with respect to the younger species Kenyapithecus wickeri and therefore is a late member of the stem hominoid radiation in the East African Miocene.

Animals↗
PubMed1999

Can we optimize electrode placement for impedance pneumography?

In this paper, we discuss issues involved in defining an optimum placement of four electrodes for impedance pneumography. We observed a general trend where the change in impedance (delta Z) decreased while the sensitivity (delta Z/Z) increased with distance between the drive and receive electrode pairs. However, the theoretical study indicated that delta Z/Z should decrease with distance. The scatter of points in the plots indicated that sensitivity was influenced by factors other than distance. The correlation coefficient between the theoretical and measured delta Z/Z was low, but significant. This suggested that the best electrode configuration can be derived from the theoretical data. High delta Z/Z was obtained when the drive and receive electrode pairs were placed close to the lungs and in different horizontal planes.

Adult↗
PubMed1999

Lack of evidence for tachykinin NK1 receptor-mediated neutrophil accumulation in the rat cutaneous microvasculature by thermal injury.

The effect of the non-peptide selective tachykinin NK1 receptor antagonist SR140333 has been investigated on oedema formation and neutrophil accumulation induced by thermal injury (50 degrees C for 5 min), mustard oil, substance P, the tachykinin NK1 agonist GR73632, and interleukin-1beta in the abdominal skin of the anaesthetised rat. SR140333 significantly inhibited (120 nmol/kg i.v.) or prevented (240 nmol/kg i.v.) the early oedema formation (0-10 min) induced by thermal injury. However, a dosing strategy which blocked NK1 receptors for 5 h (SR140333, 240 nmol/kg i.v. + 240 nmol/kg s.c.) failed to influence neutrophil accumulation measured 5 h after thermal injury. Thus, the neurogenic component mediated by NK1 receptors is important to elicit the early oedema formation, but does not influence subsequent neutrophil accumulation. Topical application of mustard oil (2%), a neurogenic inflammation stimulant, caused NK1 receptor-mediated early neurogenic plasma extravasation, but did not induce cutaneous neutrophil accumulation over 5 h. Substance P and GR73632 at high doses (1 nmol/site) also failed to elicit neutrophil accumulation. Neutrophil accumulation induced by interleukin-1beta (0.03-3 pmol i.d.) was not affected by SR140333 pretreatment. In conclusion, despite an early pronounced tachykinin NK1 receptor-dependent oedema response after thermal injury, the results suggest that subsequent neutrophil accumulation is not mediated by NK1 receptors. Furthermore, we have not obtained any evidence to suggest that either endogenous or exogenous tachykinins can directly induce neutrophil accumulation in the rat cutaneous microvasculature.

Abdomen↗
PubMed1999

Bovine arylalkylamine N-acetyltransferase activity correlated with mRNA expression in pineal and retina.

Arylalkylamine N-acetyltransferase (AA-NAT, E. C. 2.3.1.87) is the enzyme that catalyzes the transfer of an acetyl group from acetyl-CoA to serotonin to form N-acetylserotonin (NAS) in the indoleamine biosynthetic pathway. Bovine pineal AA-NAT, partially purified on an anion exchange column, displayed an 8-fold higher enzymatic activity in pineals from animals killed in early morning (0800) compared to an afternoon group (1430). Poly A(+) mRNA was isolated from early morning bovine pineals, used to construct a mammalian expression cDNA library (lambdaZAP Express), and then screened with a rat AA-NAT cDNA to isolate a 924 basepair cDNA that encodes the bovine pineal AA-NAT. The amino acid sequence alignment reveals that bovine AA-NAT shares 94.20%, 78.54%, 76.33% and 56.3% identity to ovine, rat, human and chicken sequences, respectively. Northern blot analysis demonstrates a 0.7-fold higher mRNA level in pineal glands taken from animals from the 0800 time-point compared with mRNA from the 1430 time-point. AA-NAT mRNA was expressed at high levels in pineal and retina, but the message was undetectable in adrenal, cerebellum, cortex, small intestine, testis and thyroid. Based on the significant identity of amino acid sequence and the similar mRNA expression pattern, these data suggest that the bovine AA-NAT is more analogous to the ovine rather than either the rat, human or chicken AA-NAT.

Animals↗
PubMed1999

South Turkwel: a new pliocene hominid site in Kenya.

New fossils discovered south of the Turkwel River in northern Kenya include an associated metacarpal, capitate, hamate, lunate, pedal phalanx, mandibular fragment, and teeth. These fossils probably date to around 3.5 m.y.a. Faunal information suggests that the environment at South Turkwel was predominantly bushland. The mandibular and dental remains are fragmentary, but the postcranial fossils are informative. Comparisons with Australopithecus, modern human, chimpanzee and gorilla hand bones suggest that the Turkwel hominid was most like Australopithecus afarensis and A. africanus. Carpometacarpal articulations are intermediate between those of modern humans and African apes, suggesting enhanced gripping capabilities compared with extant apes. The hamulus was strikingly large, similar in proportion only to Neandertals and some gorillas, suggesting the presence of powerful forearms and hands. There are no indicators of adaptations to knuckle-walking or suspensory locomotion in the hand, and the pedal phalanx suggests that this hominid was habitually bipedal.

Animals↗
PubMed1999

Phylogeny of "Oxycanus" lineages of hepialid moths from New Zealand inferred from sequence variation in the mtDNA COI and II gene regions.

The phylogeny of the New Zealand hepialid moths was estimated from a 527-bp nucleotide sequence from the mitochondrial DNA cytochrome oxidase subunit I and II gene regions. New haplotypes were identified for Wiseana cervinata, W. copularis, and W. signata. Phylogenetic reconstructions using maximum parsimony and maximum likelihood methods indicated that the four hepialid lineages Aenetus, Aoraia, "Oxycanus" Cladoxycanus, and "Oxycanus" s. str. hypothesized by Dugdale (1994) based on a morphological taxonomic revision were monophyletic within New Zealand. Addition of exemplars from the Australian genera Fraus, Jeana, Oxycanus, and Trictena to the data set tentatively support the monophyly of the New Zealand "Oxycanus" lineages. Estimated times of divergence for the genus Wiseana taxa fitted well with known geological events and suggest that the genus may have diverged 1-1.5 mya.

Animals↗
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↗
PubMed1999

Relatives' lived experiences of complementary therapies in a critical care department--a phenomenological study.

This phenomenological study examined relatives' lived experiences of complementary therapies in the Department of Critical Care Medicine at Royal Hobart Hospital. Participants in the study, 20 relatives of critically ill patients, were involved in a non-structured, audiotaped interview. Subsequently, transcripts were analysed using a phenomenological transformative process to identify common themes in the text. Study findings suggested four emerging conceptual categories, which with further analysis uncovered the essence of the phenomenon as extending and enriching a caring atmosphere.

Adolescent↗
PubMed1999

Incidence of presumed cytomegalovirus retinitis in HIV-infected pediatric patients.

INTRODUCTION: Large population studies of adult patients suggest an incidence of cytomegalovirus (CMV) retinitis as high as 19% to 20% as a late complication of adult HIV infection. We conducted this prospective study of a large cohort of HIV-infected children to determine the incidence of CMV retinitis in HIV-infected children. METHODS: From January 1984 to August 1997, 173 HIV-infected children were followed up for an average of 55.3 months (13-164 months). The patients were seen in the Department of Pediatrics at least once every 6 months. Ophthalmologic examinations were initiated when a patient's CD4 count dropped below 50 or sooner if required for ophthalmologic or other indications. Ophthalmologic examination was then repeated every 6 months. RESULTS: A total of 116 (67%) of 173 patients underwent ophthalmologic examination. Four (3.4%) of 116 patients had CMV retinitis at a mean time of 17.3 months (8-38 months) after their CD4 counts dropped below 20. None of the 4 patients with CMV retinitis had subjective visual complaints despite advanced retinitis. Three patients had bilateral and 1 patient had unilateral CMV retinitis. CONCLUSIONS: CMV retinitis occurred infrequently in HIV-infected pediatric patients and was diagnosed only in patients with a CD4 count below 20. Routine ophthalmologic screening examinations may not be necessary in pediatric patients until the CD4 count is below 20. Because children may not complain of decreased vision, at-risk children should undergo frequent ophthalmologic examination.

AIDS-Related Opportunistic Infections↗
PubMed1999

Multifocal ERG changes in glaucoma.

The multifocal electroretinogram (MERG) can assess regional retinal responses using analysis which gives both first-order and second-order nonlinear responses from multiple retinal regions. The retinal responses from both types of analysis showed amplitude reduction in glaucoma, suggesting that the outer and inner retinal layers are affected. These findings are in accord with the damage which has been reported in advanced glaucoma. The macular response showed a larger amplitude reduction in b-waves (first-order response) and N2P (second-order response) than did peripheral retinal responses. This indicates that loss of macular response is an important sign in glaucoma.

Adult↗
PubMed1999

Neurological features of cerebral malaria in Nigerian children.

Cerebral malaria is one of the commonest causes of an acute neurological syndrome in malaria-endemic areas. However, there are few detailed reports of findings on clinical neurological examination of the condition. The neurological features of cerebral malaria in 103 children aged 5 years or less were studied in Ibadan, Nigeria, an area of high malaria transmission. The correlation of these features with prognosis was also studied. Convulsions occurred in 87% of subjects and were in most cases of a generalized tonic-clinic nature. Abnormalities of posture were observed in 41%, abnormal tone in 70% and abnormal deep tendon reflexes in 74%. Absent corneal reflexes were found in about 14%. The time interval between the last seizure episode and presentation in hospital, abnormal posture (decerebrate or decorticate), absence of corneal reflex and depth and duration of coma were indicators of poor prognosis. In this study, cerebral malaria presented with non-specific features of diffuse, symmetrical, upper motor neurone dysfunction, and some specific neurological features were associated with poor prognosis. It is important that cerebral malaria be considered in any child with features of acute encephalopathy in a malaria-endemic area. Careful clinical examination of such children is essential as neurological features of the condition may provide a clue to prognosis.

Child, Preschool↗
PubMed1999

Decisions about prenatal testing for chromosomal disorders: perceptions of a diverse group of pregnant women.

We conducted a study to elucidate factors influencing women's decisions regarding prenatal genetic screening for and diagnosis of chromosomal disorders and to learn about their experiences with these tests and with the medical system. Using focus group interviews and questionnaire assessments, we obtained detailed impressions of a diverse group of 75 pregnant women. Participants varied with respect to race/ethnicity, religious background, and reproductive history, as well as in their decisions about use of prenatal screening and diagnostic testing. Substantial variation surfaced in attitudes toward testing. Factors influencing women's views included available resources, feelings about having a child with Down syndrome, moral beliefs, family and social influences, perceptions of one's own health, the difficulty of becoming pregnant, and willingness to put the fetus at elevated miscarriage risk. Such findings indicate that age-based policies regarding access to prenatal diagnoses that, among other reasons, are based on the balance of risks between bearing a child with a chromosomal abnormality versus procedure-related loss are incompatible with the range of concerns that women bring to this decision and the weight individual women may assign to the outcomes.

Abortion, Eugenic↗
PubMed1999

Progression of myopia in Hong Kong Chinese schoolchildren is slowed by wearing progressive lenses.

PURPOSE: In Chinese societies, primary and secondary schoolchildren perform large amounts of reading and homework and thus spend long periods performing near work during their growth years. Progressive lenses, which can permit a focused retinal image at distance, intermediate, and near, without accommodation, may slow the development of myopia. This paper reports results of a 2-year longitudinal study to examine the effects of progressive lenses on myopia progression in myopic Chinese children; these children were aged between 9 and 12 years at the beginning of the study. METHODS: Prestudy vision screening tests and five examinations, which included noncycloplegic refraction, were conducted at half-yearly intervals. Of those who completed the study, 32 children wore single vision (SV) lenses (the SV group) and 36 wore progressive lenses; of the latter, 22 wore a +1.50 D addition (the P1 group) and 14 wore a +2.00 D addition (the P2 group). Refractive error, corneal curvature, axial length, vitreous depth, and intraocular pressure were measured at every examination. Height was measured as an index of general growth. RESULTS: Progressive lenses significantly retarded the progression of the myopia in these children. Initially, the mean refractive error of the SV group was -3.67 D, of the P1 group was -3.73 D, and of the P2 group was -3.67 D. The mean myopic progressions over the 2 years of the study were -1.23, -0.76, and -0.66 D for the SV, P1, and P2 groups, respectively. CONCLUSION: Progressive lenses reduce the progression of myopia. It may be that the interaction of the progressive lenses with the accommodation system is the cause of this reduction in myopia progression because the +2.00 D addition appeared more effective than the +1.50 D addition in slowing the progression.

Child↗
PubMed1999

Test of an educational brochure on advance directives designed for well-elderly people.

The aim of this study was to test an advance directive brochure designed especially for well-elderly people. The brochure was developed using information from literature on preparing educational materials and from information gained from well-elderly focus groups. The information sought was in regard to what they knew and what they wanted to know about advance directives and what they found appealing in brochures on advance directives. Twenty well-elderly people participated in the study. Prior to data collection, the brochure was given to 10 nurses who were asked to evaluate it according to the Bernier Instructional Design Scale 2. Out of a possible 280 points, the brochure received 244. The participants in the study were asked to read the brochure and answer 15 questions about the content, user friendliness, and attractiveness of the brochure. The overall results were positive. The first five questions had to do with the appearance of the brochure. All 20 participants responded favorably to these questions. The next 10 questions had to do with understanding the content. A simple percentage was used to calculate the results. The participants understood 90.5% of the content. Based on these results, the brochure should be used in future intervention research and in discussions regarding the education of well-elderly people and the drafting of advance directives.

Advance Directives↗
PubMed1999

Physicians' transmission prevention assessment and counseling practices with their HIV positive patients.

Physicians can help prevent transmission of HIV by assessing HIV positive patients for risky sexual and needle-sharing behaviors, and by providing risk reduction counseling. From 1995 to 1997, we gathered data on the HIV transmission prevention assessment and counseling practices of 44 San Francisco Bay area physicians in face-to-face, semistructured interviews. A refined coding scheme and constant comparative analytic method were used. Although physicians varied in their responses to coded items, two styles of engagement, at the extremes, emerged from the data: "consultant" and "collaborator." Consultants conducted transmission prevention assessment and counseling during initial visits or upon medical cues (e.g., presence of sexually transmitted diseases) and viewed themselves primarily as information sources, whereas collaborators regularly conducted transmission prevention counseling and viewed themselves as actively helping patients reduce transmission risk. Physicians who fell between the two styles generally did not conduct regular counseling themselves, but many used referrals to health educators. The findings suggest that consultant and collaborator styles may influence patients differently, and offer insight into the role that physicians can play in transmission prevention with HIV positive patients.

Adult↗