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Biomedical subjects

S Dawson

Publications and source records attributed to S Dawson.

At least 91 records · Page 5Linked to original sources
PubMed1996

Altered mineral metabolism and bone mass in children during treatment for acute lymphoblastic leukemia.

Children with acute lymphoblastic leukemia (ALL) often develop bone pain, abnormal gait, and unusual fractures while in remission and receiving continuing chemotherapy. A prospective longitudinal cohort study was undertaken of bone mass and biochemical mineral status in 40 consecutive children (27 male, 13 female, aged 0.3-17.0 years) receiving therapy on the Dana-Farber Cancer Institute protocol 87-01. Radiography, lumbar spine dual-photon absorptiometry, and biochemical measurements of mineral status were performed at diagnosis and at 6-month intervals throughout 24 months of chemotherapy. Eleven patients were not completely evaluated (4 deaths and 7 off study). Radiographic evidence of osteopenia was observed in 10, 64, and 76% at diagnosis, 12 and 24 months, respectively. Fractures occurred in 39% of children during treatment. Reduction in bone mineral content (BMC), as measured by Z scores, occurred in 64% of patients and was most severe in those greater than 11 years of age at diagnosis. Reduction in BMC during the first 6 months of therapy had a positive predictive value of 64%, while an increase in BMC had a negative predictive value of 82% for subsequent fracture. By 6 months of therapy, 31/37 (84%) children were hypomagnesemic, of whom 16 (52%) were hypermagnesuric. Plasma osteocalcin was subnormal at diagnosis in 29/40 (73%) but increased to normal by 6 months of treatment. Vitamin D status was normal throughout, but plasma 1,25-dihydroxyvitamin D remained subnormal in greater than 70% of children. Urinary cross-link N-telopeptide was normal at diagnosis and became elevated in 58% of children by the end of therapy. Suppressed bone mineralization is evident at diagnosis in a minority of children with ALL. Skeletal morbidity and a reduction in bone mineral mass become more prevalent during treatment, with increased bone resorption, perhaps mainly as a consequence of corticosteroid administration.

Adolescent↗
PubMed1996

Studies on natural transmission of Bordetella bronchiseptica in cats.

Two pregnant specific-pathogen-free (SPF) cats, from a colony endemically infected with Bordetella bronchiseptica, were housed under barrier conditions in the latter stages of pregnancy in order to study the possible transmission of the organism to their kittens. Both queens had antibody titres to Bordetella bronchiseptica of 1 in 320 at the start of the experiment but did not shed Bordetella bronchiseptica until 9 days and 6 weeks after parturition, respectively. Five of the nine kittens had detectable maternally-derived-antibody to Bordetella bronchiseptica which declined to < or = 1 in 40 by two weeks of age. Kittens were weaned at 12 weeks of age. No Bordetella bronchiseptica was isolated from any of the kittens and none seroconverted over this time. At 15 1/2 weeks of age, half of each litter were housed separately and inoculated intra-nasally with 10(8) colony-forming-units B. bronchiseptica. Mild signs of upper respiratory tract disease were seen and the organism was isolated for 19 weeks following inoculation when the experiment ended. Seroconversion occurred at 4 weeks postinoculation. Oral treatment of two clinically-recovered kittens with doxycycline once a day did not eliminate shedding.

Animals↗
PubMed1996

Feline calicivirus strain differentiation using monoclonal antibody analysis in an enzyme-linked immuno-flow-assay.

Six monoclonal antibodies raised against feline calicivirus (FCV) strain F9 were used in an enzyme-linked immuno-flow-assay (ELIFA) to analyse 55 isolates of FCV. Forty seven field isolates were obtained from cats with acute oral/respiratory disease, chronic oral lesions, and from cats showing vaccine reactions, i.e. clinical signs of FCV infection shortly after vaccination. Eight reference strains including F9 and three vaccine strains based on F9 were also examined. All of the strains of F9, derived from various sources, reacted with all six of the monoclonal antibodies, whereas some of the field isolates did not react with any. In general, the field isolates showed a spectrum of reactivities and selected isolates could be distinguished. However, there were no clear cut differences between the clinical groups. Overall, the oral/respiratory group showed less reactivity with the monoclonals, suggesting they were less related to F9. Although the other groups appeared to be more closely related to F9, none of the isolates tested reacted with all six monoclonal antibodies.

Animals↗
PubMed1996

Circadian relationships between circulating atrial natriuretic peptides and serum calcium and phosphate in healthy humans.

Long-acting natriuretic peptide (LANP), vessel dilator (VSDL), and atrial natriuretic factor (ANF) consisting of amino acids (aa) 1 to 30, 31 to 67, and 99 to 126, respectively, of the 126-aa ANF prohormone circulate in humans. Among the biologic properties of these peptides is the ability of ANF to decrease intracellular calcium concentrations. To determine if atrial natriuretic peptides are directly related to serum calcium and/or phosphate in healthy normocalcemic humans, we examined 21 24-hour profiles of VSDL, LANP, ANF, and serum calcium and phosphate in 14 healthy humans. VSDL, LANP, and ANF each had significant (P < .001) circadian rhythms, with peak concentrations late during sleep (at 4:00 AM) being nearly twice the concentrations in the afternoon and evening. Serum calcium and phosphate also had significant circadian rhythms (P < .001) with troughs nearly opposite to those of the atrial natriuretic peptides, suggesting that atrial peptides may be important in the modulation of the circadian rhythms of calcium and phosphate. The nearly identical circadian rhythms of the atrial natriuretic peptides and of parathyroid hormone (PTH) reported by others, along with evidence that PTH may increase atrial peptide release, suggest that some of the effects attributed to PTH may be mediated by atrial natriuretic peptides.

Adult↗
PubMed1996

Abnormal expression of integrin alpha 6 beta 4 in cervical intraepithelial neoplasia.

We have used subunit-specific monoclonal antibodies (MAbs) and immunohistochemistry to examine the distribution of integrin alpha 6 beta 4 in normal ectocervical epithelium and various grades of cervical intraepithelial neoplasia (CIN). Antibodies were first characterised by immunoprecipitation from two surface-labelled tumour cell lines. Monoclonal antibody G71 was found to precipitate integrin beta 4 from BeWo but not T47D cells, while other anti-beta 4 antibodies precipitated beta 4 from both cell lines. Both G71 and an antiserum to the C-terminal peptide of beta 4 precipitated free beta 4 from surface-iodinated BeWo cells. Neither antibody recognised truncated beta 4 chains observed at approximately 160 kDa. These data suggest that different isoforms of beta 4 are expressed in different tumour cell lines, and that there may be a pool of beta 4 at the cell surface that is not complexed to alpha 6. In normal cervix, both the alpha 6 and beta 4 subunits occur at the basal surface of the basal cell layer. In CIN, the distribution is markedly altered, with strong expression of alpha 6 and beta 4 in the upper cell layers of the ectocervical epithelium. All 40 cases of CIN that were studied exhibited this alteration. Furthermore, the extent of extrabasal staining appeared to correspond with the grade of CIN. The form of integrin beta 4 recognised by antibody G71 also appears in the upper cell layers in CIN, but it shows a more restricted distribution than the normal isoform.

Amino Acid Sequence↗
PubMed1996

UCLA liver transplantation: analysis of immunological factors affecting outcome.

From 1988 to 1993, UCLA completed 938 first and 1,146 total orthotopic liver transplants (OLT). Race analysis demonstrated a 1-year patient survival of 89% in Blacks (n = 45) versus 80% in Whites (n = 492, p < 0.02), with no significant difference shown between Hispanics (n = 278) and Whites. The 1-year patient survival in Asians was 50% (n = 58, p < 0.02 vs. Whites) even when hepatitis B was excluded (59%, n = 43). The 1-year patient survival of hepatitis B surface antigen positive Asians (n = 15) was only 21% (p < 0.02 vs. all others). OLT patients whose panel reactive antibody (PRA) was < 10% (n = 339) demonstrated no graft or patient survival advantage versus recipients whose PRA was > 10% (n = 71). A positive antidonor flow cytometry crossmatch (> 30 mean channel shifts, n = 76) was associated with a decreased 1-year graft survival (56% vs. 73%, p < 0.05) when compared to flow negative recipients (n = 185). Graft survival for 0 DR mismatches was 74% at 1 year compared with 57% for 1 DR mismatches (p < 0.02) and 59% for 2 DR mismatches (p < 0.02).

Adult↗
PubMed1996

Circadian relationships between circulating atrial natriuretic peptides and serum sodium and chloride in healthy humans.

Long-acting natriuretic peptide (LANP), vessel dilator (VSDL), and atrial natriuretic factor (ANF) consisting of amino acids 1-30, 31-67, and 99-126 of the 126 amino acid ANF prohormone, respectively, circulate in humans and have potent natriuretic properties. To determine whether these peptides have a direct relationship to serum Na and/or Cl, we examined 21 24-hour profiles of these peptides and Na and Cl in 14 healthy humans. LANP, VSDL, ANF, and Cl had significant (p < 0.001) circadian rhythms with peak concentrations at 04.00 h. The circadian rhythm of serum Na was exactly opposite. Sodium correlated negatively with LANP (p = 0.021) and ANF (p = 0.007), while Cl correlated positively with LANP (p = 0.003) and VSDL (p = 0.001). These data suggest that the atrial peptides may be important for the maintenance of serum Na and Cl within their normal ranges and in the modulation of their daily circadian rhythms.

Adult↗
PubMed1996

Splenectomy for haematological disease.

The role of splenectomy in haematological disease appears to be changing. This single centre, retrospective study was carried out to document the indications for splenectomy and its outcome over a 7-year period and to compare it with the preceding 7-year period. Sixty-four patients underwent splenectomy in the study period, the main indication being idiopathic thrombocytopenic purpura. There was one post-operative death and morbidity was seen in 40 (63%) patients. Splenectomy was successful in achieving the desired aim in 51 (80%) patients. Approximately 40% fewer patients underwent splenectomy in the study period compared with the preceding 7 years despite there being an overall increase of 123 (633 vs. 540) patients treated for haematological disease in this period. The reason for this observation was the fall in the number of splenectomies performed for Hodgkin's disease and auto-immune haemolytic anaemia.

Female↗
PubMed1995

Responding to cough: Boholano illness classification and resort to care in response to childhood ARI.

A qualitative study into the health seeking behaviour of caretakers in response to ARI in children under five years of age was conducted in the province of Bohol, the Philippines. The study was designed to compliment survey data generated from a long running ARI intervention project, specifically to explain behaviours identified as problematic by the project. Results indicate the importance of folk diagnosis as a basis for selection of first resort for care in the management of childhood ARI. A cultural category, piang, was identified as a major factor influencing health seeking behaviour and delay in consulting the biomedical system where serious ARI exists. In addition, caretakers' financial situation and social contacts are important in their decision to seek biomedical assistance and are often implicated in delay in presentation and acting upon referral to hospital.

Acute Disease↗