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S J Peacock

Publications and source records attributed to S J Peacock.

29 records · Page 2Linked to original sources
PubMed1996

The incorporation and release of bovine serum albumin from poly(beta-hydroxybutyrate-hydroxyvalerate) microspheres.

Spherical microporous matrix type microspheres composed of 330 kD P(HB-HV) (10.8% HV) 20%PCL II containing a range of %BSA loadings have been fabricated using a single emulsion technique with solvent evaporation. Microspheres were generated in high yield (> 75%) and the percentage incorporation of BSA had no significant effect on microsphere size distribution, typically 6-50 microns in diameter with a mean of 26.28 +/- 2.34 microns, n = 25, for 20% BSA loaded microspheres. The loss of BSA both by partitioning into the aqueous continuous phase and through micropores generated during the precipitation of the fabrication polymer concomitant with solvent evaporation resulted in a low encapsulation efficiency (< 15%). When the total cumulative release of BSA was expressed as a percentage of the actual total BSA incorporated, BSA release was only marginally influenced by the theoretical percentage loading suggesting that the amount and duration of BSA release in vitro was initially influenced as much by micropore number and diameter as by the extent of matrix BSA loading and detectable levels of BSA release could be monitored for up to 24 days.

3-Hydroxybutyric Acid↗
PubMed1996

In vitro biodegradation of poly(beta-hydroxybutyrate-hydroxyvalerate) microspheres exposed to Hanks' buffer, newborn calf serum, pancreatin and synthetic gastric juice.

Spherical BSA loaded microporous matrix type microspheres composed of P(HB-HV) blended with 20% PCL II and fabricated using 0/W emulsification with solvent evaporation have been incubated in Hanks' buffer, pH 7.4; newborn calf serum; 1.5% pancreatin and synthetic gastric juice over 30 days and their percentage weight loss (PWL) and changes in ultrastructural morphology monitored by gravimetry and SEM respectively. The greatest percentage weight loss was observed after incubation in newborn calf serum and decreased in the order newborn calf serum > pancreatin > synthetic gastric juice > Hanks' buffer. Only incubation in synthetic gastric juice and Hanks' buffer produced a significant increase in PWL with increasing theoretical percentage loading. Incubation in Hanks' buffer produced limited surface erosion leading to an increase in micropore diameter and the coalescence of micropores to from surface pits. With pancreatin, surface erosion led to the disappearance of surface micropores and a reduction in microsphere diameter. Subsequent fracturing of the microsphere surface facilitated the breakup of the matrix. In synthetic gastric juice there was little surface erosion and surface flaking and bulk erosion were responsible for the breakup of the matrix. In newborn calf serum, spherical shape was maintained despite a reduction in microsphere diameter. Bulk erosion in the form of large macroporous pits extending deep into the matrix gave the microspheres a hollow appearance. The enhanced biodegradation in NCS and significant surface erosion in pancreatin was assumed to be due to the effects of exogenous enzyme activity in addition to simple ester hydrolysis.

3-Hydroxybutyric Acid↗
PubMed1995

Two cases of infected atherosclerotic aneurysms and a comparison with infective endocarditis.

Two cases of infected atherosclerotic aneurysms thought to have arisen following haematogenous seeding of atheromatous lesions are described. Although infective endocarditis also arises by the haematogenous route, there are striking contrasts in both the range and therefore likely source of organisms, together with a perceived difference in the rate of blood-culture positivity. This case report provides a focus for discussion of these observations.

Aged↗
PubMed1995

Angiotensin II formation in the intact human heart. Predominance of the angiotensin-converting enzyme pathway.

It has been proposed that the contribution of myocardial tissue angiotensin converting enzyme (ACE) to angiotensin II (Ang II) formation in the human heart is low compared with non-ACE pathways. However, little is known about the actual in vivo contribution of these pathways to Ang II formation in the human heart. To examine angiotensin II formation in the intact human heart, we administered intracoronary 123I-labeled angiotensin I (Ang I) with and without intracoronary enalaprilat to orthotopic heart transplant recipients. The fractional conversion of Ang I to Ang II, calculated after separation of angiotensin peptides by HPLC, was 0.415 +/- 0.104 (n = 5, mean +/- SD). Enalaprilat reduced fractional conversion by 89%, to a value of 0.044 +/- 0.053 (n = 4, P = 0.002). In a separate study of explanted hearts, a newly developed in vitro Ang II-forming assay was used to examine cardiac tissue ACE activity independent of circulating components. ACE activity in solubilized left ventricular membrane preparations from failing hearts was 49.6 +/- 5.3 fmol 125I-Ang II formed per minute per milligram of protein (n = 8, +/- SE), and 35.9 +/- 4.8 fmol/min/mg from nonfailing human hearts (n = 7, P = 0.08). In the presence of 1 microM enalaprilat, ACE activity was reduced by 85%, to 7.3 +/- 1.4 fmol/min/mg in the failing group and to 4.6 +/- 1.3 fmol/min/mg in the nonfailing group (P < 0.001). We conclude that the predominant pathway for angiotensin II formation in the human heart is through ACE.

Angiotensin I↗
PubMed1990

Monoclonal antibody MAC 387 recognizes a myelomonocytic antigen shared by epithelial cells in inflammatory skin diseases.

The monoclonal antibody MAC 387 recognizes an antigen expressed by human macrophages and granulocytes. Normal epidermis does not react with the antibody, but the inflamed epidermis may react. In this immunocytochemical study we have investigated the intracytoplasmic expression of the MAC 387 antigen in biopsies of a variety of skin disorders. In lichen planus the basal cells were usually negative, whilst suprabasal cells were positive. In the majority of other inflammatory dermatoses studied, there was positive staining of basal and suprabasal cells. A parallel frozen- and paraffin-section study of biopsies of cutaneous T-cell lymphomas and inflammatory conditions failed to demonstrate HLA Class II expression in the cytoplasm of keratinocytes. Expression of the MAC 387 antigen in the epidermis is directly associated with cell-mediated activity in the papillary dermis, but is not related to HLA Class II expression.

Antibodies, Monoclonal↗
PubMed1989

Heart valve measurement at autopsy can distinguish cardiac from non-cardiac causes of death.

The circumferences of the four intact cardiac valves were measured during 397 coroner's autopsies using an obturator cone to assess the value of this measurement in the postmortem diagnosis of cardiac disease. Valve sizes of cases with cardiac and noncardiac causes of death were compared using logistic regression to assess the effects of confounding variables including sex, age, height, build and the presence of chronic obstructive airways disease. Mitral valve enlargement was found to be significantly associated with cardiac death, as were build, age, and sex. Measurement of the mitral valve at autopsy can help distinguish cardiac from noncardiac causes of death.

Age Factors↗
PubMed1988

The autopsy: a useful tool or an old relic?

In a combined retrospective and prospective study, clinical and autopsy data were collected to assess the changes in autopsy rate in recent years, the attitudes of clinicians and pathologists to the autopsy, and the accuracy of ante-mortem diagnosis when compared with autopsy findings. Between 1962 and 1986, the total autopsy rate for hospital patients remained relatively constant, with an increase in Coroner's and a decrease in the hospital autopsy rate. Analysis of 5064 deaths over a 6-year period showed a significantly greater number of males than females coming to autopsy and a decrease in autopsy rate with age for both sexes. Attitudes to the autopsy were assessed using a questionnaire. The majority of clinicians considered the autopsy to be an important investigation despite new diagnostic techniques and confirmed its value in teaching and research. Seventy-seven per cent agreed that autopsy findings occasionally led to modification of the treatment of subsequent patients with the same condition. Pathologists disagreed that the autopsy is outdated in its present form and considered that not enough hospital autopsies are being requested. They also upheld its use and value in education. The cause of death as given by clinicians for a group of 60 patients was inaccurate in 12 cases.

Adult↗
PubMedDate not supplied

In vitro biodegradation of polyhydroxybutyrate-hydroxyvalerate microcapsules exposed to Hank's buffer, newborn calf serum, pancreatin and synthetic gastric juice.

Spherical microporous reservoir-type microcapsules, fabricated using a W/O/W double emulsion technique with solvent evaporation and composed of 330 kD poly(beta-hydroxybutyrate-hydroxyvalerate (P(HB-HV)) (10.8% HV)/20% PCL II containing a range of bovine serum albumin (BSA) loadings, were incubated in Hank's buffer, pH 7.4, newborn calf serum (NCS), 1.5% pancreatin and synthetic gastric juice containing 10% pepsin over 30 days, and their percentage weight loss (PWL) and change in ultrastructural morphology monitored by gravimetry and stereoscan electron microscopy (SEM), respectively. The greatest percentage weight loss from microcapsules was observed after incubation in NCS and decreased in the other NCS > pancreatin > synthetic gastric juice > Hank's buffer. Only 5, 10 and 15% bovine serum albumin (BSA) loaded microcapsules incubated in Hank's buffer and synthetic gastric juice showed a significant increase in PWL with increasing percentage BSA loading. The overall sequence of changes in structural morphology due to biodegradation occurred at different rates in the different 'physiological' media. An initial increase in micropore diameter was followed by the coalescence of microspores to form macroporous pits (Hank's buffer). Further biodegradation in NCS, pancreatin and synthetic juice was characterized by significant surface and bulk erosion. Only in pancreatin and NCS did biodegradation proceed to a loss of spherical shape and partial (pancreatin) and almost total (NCS) disruption of microcapsule structure after 30 days.

Animals↗
PubMedDate not supplied

Incorporation and release of vancomycin from poly(D,L-lactide-co-glycolide) microspheres.

Spherical monolithic microspheres, with a honeycomb-like internal architecture, composed of PLCG 50:50 and PLCG 75:25 and containing a range of vancomycin loadings, have been fabricated using a W/O emulsification with solvent evaporation technique. Microspheres were generated in high yield (80 wgt%) and vancomycin incorporation, confirmed using the displacement of DSC thermograms, had no significant effect on microsphere size distribution (5-50 microns). The vancomycin encapsulation efficiency was high (> 64%) and release profiles were characterized by a substantial initial burst release and a subsequent low-level sustained release extending up to 30 days depending upon the fabrication polymer, % vancomycin loading and incubation medium used. In both Hank's buffer and newborn calf serum the mean total cumulative release of vancomycin from microspheres increased significantly with theoretical percentage loading.

Animals↗
PubMedDate not supplied

Outcome following staphylococcal peritonitis.

OBJECTIVE: Staphylococcus spp predominate as the causative pathogen of continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis.This study evaluated the difference in morbidity and mortality between peritonitis caused by S. aureus and coagulase-negative staphylococci (CoNS). DESIGN: Prospective observational study. SETTING: A single regional dialysis unit in a teaching hospital. PATIENTS: Thirty-seven patients had S. aureus peritonitis and 65 patients had CoNS peritonitis between July 1990 and November 1995. MAIN OUTCOME MEASURES: Using the first recorded episode of peritonitis, survival analysis was performed for time to (1) death, (2) removal of peritoneal dialysis catheter, and (3) change to hemodialysis. Abdominal complications were recorded for the first and subsequent episodes. RESULTS: No difference in time to death was demonstrated for the two groups (p = 0.79), although two deaths that occurred during therapy for peritonitis were attributable to S. aureus infection. In addition, 5 patients developed serious abdominal complications related to an episode of S. aureus peritonitis. Patients with S. aureus peritonitis had a shorter time to both peritoneal dialysis catheter removal (p = 0.004) and change to hemodialysis (p = 0.014). The change in mode of dialysis was independent of catheter loss. CONCLUSION: This study highlights the serious nature of S. aureus peritonitis and confirms the need for effective preventive measures against infection by this pathogen.

Adult↗