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Biomedical subjects

P Phillips

Publications and source records attributed to P Phillips.

At least 145 records · Page 8Linked to original sources
PubMed1994

ACTH precursors characterize the ectopic ACTH syndrome.

OBJECTIVE: ACTH is secreted by the pituitary following processing of larger molecular weight precursors, proopiomelanocortin and pro-ACTH. Ectopic ACTH syndrome refers to the secretion of ACTH by non-pituitary tumours, but the predominant circulating form of proopiomelanocortin-related peptides remains unclear. PATIENTS: Fifteen patients with ectopic ACTH syndrome were compared to 20 patients with pituitary-dependent Cushing's syndrome, 22 patients with small cell lung carcinoma but no evidence of Cushing's syndrome, and 25 controls. DESIGN AND MEASUREMENTS: Measurement of plasma ACTH and ACTH precursors using specific monoclonal-based immunoradiometric assays at 0900 h and, in five patients with ectopic ACTH syndrome, at 15-minute intervals for 6-24 hours. RESULTS: ACTH precursors were grossly elevated in patients with ectopic ACTH syndrome (median 2194, range 139-18000 pmol/l) compared to patients with Cushing's disease (median 33, 8-73 pmol/l, P < 0.001), patients with small cell lung carcinomas (38, 8-117 pmol/l, P < 0.001) and controls (26, 10-39 pmol/l, P < 0.001). ACTH levels were also elevated in ectopic ACTH syndrome (0900 h median 34, 11-152 pmol/l) compared to patients with Cushing's disease (0900 h median 8, 3-19 pmol/l), but not to the same degree as ACTH precursors. In contrast with Cushing's disease, ACTH was secreted in a non-pulsatile fashion. ACTH precursors but not ACTH itself correlated with plasma cortisol in patients with ectopic ACTH syndrome (r = 0.65, P < 0.05). Chromatographic analysis of plasma from a patient with ectopic ACTH syndrome confirmed ACTH precursors and not ACTH to be the predominant circulating form. With the cross-reactivity of proopiomelanocortin and pro-ACTH in the ACTH IRMA of < 1 and < 10% respectively, ACTH precursors could represent all the ACTH immunoreactivity in patients with ectopic ACTH syndrome. CONCLUSIONS: Ectopic 'ACTH' is characterized by aberrant processing of proopiomelanocortin and should be more accurately referred to as 'ectopic ACTH precursor syndrome'.

ACTH Syndrome, Ectopic↗
PubMed1994

Cardiovascular risk factors in South Australians with diabetes.

This study ascertained the prevalence of diabetes and compared the prevalence of cardiovascular risk factors among people with and without diabetes. Data were collected as part of the South Australian Health Omnibus Survey which involved a representative population sample of 6398 adults in metropolitan and country South Australia who were interviewed in their own homes. The self-reported prevalence of diabetes was found to be 3 per cent overall. This varied from approximately 1 per cent in the 15- to 39-year age group to 10.5 per cent in people aged over 80 years. Those with diabetes had a higher prevalence of cardiovascular risk factors than those without diabetes. There is a need for improved vigilance with people who have diabetes and interventions to modify the risk factors associated with cardiovascular disease.

Adolescent↗
PubMed1994

Characterization of metal-binding bioflocculants produced by the cyanobacterial component of mixed microbial mats.

Mixed-species microbial mats that were dominated by the cyanobacterium Oscillatoria sp. and contained heterotrophic and purple autotrophic bacteria were constructed for specific bioremediation applications. When the mats were challenged with metals, production and secretion of metal-binding extracellular polysaccharide bioflocculants were observed. The concentration of these negatively charged polysaccharides was correlated with the removal of manganese from the water column beneath a surface microbial mat. Bioflocculants from an Oscillatoria sp. that was isolated from the mat were collected and concentrated for characterization. A chromatographic analysis revealed a heterogeneous population of polysaccharides with respect to charge density and molecular size. The subpopulation of polysaccharides which exhibited the highest level of flocculating activity was polyanionic and had a molecular weight of more than 200,000. A glycosyl analysis of the bioflocculants revealed the presence of galacturonic acid (2.2%) and glucuronic acid (1.86%). The presence of these components, which were negatively charged at the pH levels generated by the mats during photosynthesis (pH > 7.5), may account for the metal-binding properties of the mats.

Binding Sites↗
PubMed1994

Redefining the anatomy of the anterior tibialis tendon.

The observation that, when performing a split anterior tibialis tendon transfer, a twist develops as the distal segment is brought into position on the lateral side of the foot led to our hypothesis that, as a consequence of foot rotation during embryologic development, rotation of the tendon of the anterior tibialis muscle also occurs and can be seen in the adult. Ten unembalmed human lower extremities were examined with regard to the macrostructure of the anterior tibialis tendon. In all 10 specimens, the fibers rotated through 90 degrees from the musculotendinous junction to the insertion on the first cuneiform and metatarsal. The tendon was then split, releasing the first metatarsal insertion in five specimens and the first cuneiform insertion in five. Lateral transfer of the first metatarsal-released group produced a crossing over proximally of the tendon as the fibers came from the medial side of the musculotendinous junction. Lateral transfer of the first cuneiform-released group produced no crossing over proximally as the fibers came from the lateral side of the musculotendinous junction. During a split anterior tibialis tendon transfer, release of the cuneiform insertion will avoid the proximal twisting seen with first metatarsal release and allows for a more direct line of pull of the muscle on the tendon.

Cadaver↗
PubMed1994

Androgen manipulation and vasopressin binding in the rat brain and peripheral organs.

It is now widely recognized that there is a sexual dimorphism in the development of arginine vasopressin (AVP) immunoreactivity in certain parts of the brain, and that changes in brain AVP immunoreactivity change with manipulation of androgen status. The aim of this experiment was to determine specifically any AVP receptor changes in response to manipulation of androgen levels using a selective V1 antagonist radioligand. Following castration, plasma testosterone levels fell and AVP immunoreactivity was reduced in the lateral septum and bed nucleus of the stria terminalis. With testosterone supplementation in castrated animals, the immunoreactivity in these regions was restored to a higher degree than in sham-operated animals. Central and peripheral V1 AVP receptor binding (as determined using the selective AVP V1 antagonist radioligand [125I](d(CH2)5,sarcosine7)AVP was not changed in any of the brain regions studied or in liver or kidney membranes from the three groups. This study demonstrates that there is no change in brain AVP receptor binding despite changes in regional AVP immunoreactivity in the brain, and excludes any confounding interaction with changes in oxytocin receptors.

Androgens↗
PubMed1994

Day-night blood pressure variation in normotensive, normoalbuminuric type I diabetic subjects. Dippers and non-dippers.

OBJECTIVE: To examine day-night blood pressure (BP) variation in normotensive, normoalbuminuric subjects with type I diabetes and to assess the prevalence of an impaired nocturnal BP fall. RESEARCH DESIGN AND METHODS: Fourteen healthy volunteers and 13 normotensive, normoalbuminuric subjects with type I diabetes were studied with an ambulatory sphygmomanometric device for 24 h. RESULTS: No significant difference was found between diabetic and control groups with regard to daytime systolic blood pressure (sBP) or diastolic blood pressure (dBP). However, the mean nighttime sBPs (P < 0.01) and dBPs (P = 0.01) were significantly higher in the diabetic group compared with the control group. Furthermore, the night/day ratio for both sBP (P < 0.01) and dBP (P < 0.01) was significantly higher in the diabetic group. Approximately half of the diabetic subjects studied were non-dippers when defined either by a nocturnal fall in sBP/dBP of < 10/5 mmHg (5/13 vs. 0/14, P < 0.05: diabetic group vs. control group) or a day to night fall in either sBP (7/13 vs. 2/14, P < 0.05) or dBP (6/13 vs. 0/14, P < 0.01) of < 10%. CONCLUSIONS: Ambulatory BP may reveal impaired nocturnal BP fall in normotensive, normoalbuminuric subjects with type I diabetes. These subjects may be at greater risk of certain complications as a consequence of an increased BP burden.

Adult↗
PubMed1994

Safety profile of didanosine among patients with advanced HIV disease who are intolerant to or deteriorate despite zidovudine therapy: results of the Canadian Open ddI Treatment Program.

The aim of this study was to ascertain the safety profile of didanosine (Videx; ddI) within the Canadian Open Treatment Program. Symptomatic HIV+ subjects with AIDS or ARC or CD4 < 200/mm3 were eligible to receive didanosine if they were either (a) intolerant to zidovudine (Retrovir, ZDV) or (b) deteriorating despite ZDV therapy. The dose of didanosine (powder formulation) was based on body weight as follows: > or = 75 kg, 375 mg b.i.d.; 50-74 kg, 250 mg b.i.d.; 35-49 kg, 167 mg b.i.d. Participants were monitored with physical examinations and prespecified laboratory studies by their treating physicians on a monthly basis. Follow-up data were collected in a central database through five regional coordinators. A total of 168 physicians across Canada participated in the program, and 825 subjects who started didanosine after July 1, 1990, were included in the analysis. Of these, 97% were male, 88% homosexual, and 59% had a prior diagnosis of AIDS. Reasons for enrolling was ZDV intolerance in 39%, failure in 25%, both in 32%, and other in 4%. Data were prospectively collected until July 31, 1991. Total follow-up was 3,440 patient-months and median follow-up was 4.3 months. A total of 78 deaths were reported, 44 of which occurred within a month after the last dose of didanosine. Causes of death included AIDS-related unspecified causes (13 patients), MAC (11), wasting (7), AIDS-related CNS involvement other than OI's (7), Kaposi's sarcoma (7), Pneumocystis carinii pneumonia (6), sudden death, including suicides and accidents (6), lymphoma (5), toxoplasmosis (4), cryptococcosis (4), cytomegalovirus (3), unspecified causes (2), tuberculosis (1), PML (1), and disseminated histoplasmosis (1). Didanosine was discontinued in 140 (17%) subjects during the study period due to adverse events.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗