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Biomedical subjects

T A Taylor

Publications and source records attributed to T A Taylor.

15 recordsLinked to original sources
PubMed2001

The role of type I collagen in aortic wall strength with a homotrimeric.

PURPOSE: Elastin and collagen (types I and III) are the primary load-bearing elements in aortic tissue. Deficiencies and derangements in elastin and type III collagen have been associated with the development of aneurysmal disease. However, the role of type I collagen is less well defined. The purpose of this study was to define the role of type I collagen in maintaining biomechanical integrity in the thoracic aorta, with a mouse model that produces homotrimeric type I collagen [alpha1(I)]3, rather than the normally present heterotrimeric [alpha1(I)]2 alpha2(I) type I collagen isotype. METHODS: Ascending and descending thoracic aortas from homozygous (oim/oim ), heterozygous (oim /+), and wildtype (+/+) mice were harvested. Circumferential and longitudinal load-extension curves were used as a means of determining maximum breaking strength (Fmax) and incremental elastic modulus (IEM). Histologic analyses and hydroxyproline assays were performed as a means of determining collagen organization and content. RESULTS: Circumferentially, the ascending and descending aortas of oim /oim mice demonstrated significantly reduced Fmax, with an Fmax of only 60% and 23%, respectively, of wildtype mice aortas. Oim/oim descending aortas demonstrated significantly greater compliance (decreased IEM), and the ascending aortas also exhibited a trend toward increased compliance. Reduced breaking strength was also demonstrated with longitudinal extension of the descending aorta. CONCLUSION: The presence of homotrimeric type I collagen isotype (absence of alpha2(I) collagen) significantly weakens the aorta. This study demonstrates the integral role of type I collagen in the biomechanical and functional properties of the aorta and may help to elucidate the role of collagen in the development of aneurysmal aortic disease or dissection.

Analysis of Variance↗
PubMed2000

Vascular and endothelial actions of inhibitors of substance P amidation.

Formation of mature active neuropeptides such as substance P (SP) from their glycine extended precursors entails alpha-amidation of peptide precursors by the sequential enzymatic action of peptidylglycine alpha-monooxygenase (PAM) and peptidylamidoglycolate lyase (PGL). We reported that these two enzymes that can produce mature active neuropeptides are present in cultured bovine aortic endothelial cells (BAECs). We hypothesize that alpha-amidation of peptides occurs in endothelial cells and that these peptides are critically involved in the overall regulation of cardiovascular function. In this study, this hypothesis was tested using specific amidation inhibitors to determine their effects on the actions of SP and its glycine-extended precursor (SP-Gly). We have found that SP and SP-Gly are equipotent in stimulating nitric oxide (NO) release by BAECs. At 10(-5) M, the specific inhibitors of PAM (4-phenyl-3-butenoic acid; PBA) and PGL (5-acetamido-2,4-diketo-6-phenyl-hexanoic acid and its methyl ester) reduced NO basal release by 40, 34, and 45%, respectively. They also reduced the production of NO induced by SP-Gly by 63, 68, and 69%, respectively, but had no effect on NO production in response to either SP or acetylcholine. SP and SP-Gly also were equipotent in relaxing rat aortic segments. The vasorelaxation to SP-Gly was endothelium dependent and inhibited by the NOS antagonist L-nitroarginine methyl ester (L-NAME), but it was not affected by inhibition of prostaglandin synthesis. Inhibitors of both PAM and PGL significantly reduced the vasorelaxing actions of SP-Gly, whereas responses to SP were not affected. A cumulative infusion of PBA into the femoral artery of rabbits, at final concentrations of 2.4, 24, and 240 microM for 20 min each, increased the vascular resistance (VR), indicating the tonic production of vasodilating amidated peptide(s). This effect was maximum at 60 min after infusion (20.5 +/- 4.7 vs. 8.2 +/- 0.7 mm Hg/ml/min; p < 0.05). These results suggest that endothelial cells can produce mature SP from its SP-Gly precursor and that a product of peptide alpha-amidation tonically stimulates endothelial cell NO release to control vascular tone.

Amidine-Lyases↗
PubMed1997

Immunoassay for thyroxine (T4) in serum using capillary electrophoresis and micromachined devices.

As part of our ongoing effort to develop electrophoretic assay technology for clinical diagnostics, we describe a competitive immunoassay for the determination of serum thyroxine (T4) based on electrophoresis and laser induced fluorescence (LIF). Measurements of total T4 are useful for the clinical evaluation of thyroid function. A fluorescein thyroxine conjugate was utilized in conjunction with a polyclonal antibody preparation as assay reagents. Capillary electrophoresis (CE) conditions tolerant of the direct injection of serum without extraction or other sample preparation steps were developed and used for quantitation of total T4 in serum. We have been exploring the use of micromachined devices with arrays of channels for high assay throughput. Our assay protocol was carried in a microchip format. The results illustrate that gains in speed can be additionally achieved, with the electrophoretic separation of free from bound labelled T4 being performed in about 15 s for serum samples.

Electrophoresis, Capillary↗
PubMed1996

Microchip electrophoretic immunoassay for serum cortisol.

An immunoassay performed using a microchip electrophoretic system is described. Separation and quantitation of free and bound labeled antigen in a competitive assay are carried out in channels micromachined into fused silica substrates. Such microchips are attractive because of their small size, ruggedness, and amenability to automated handling. The assay achieves the determination of cortisol in blood serum over the range of clinical interest (1-60 micrograms/dL) without the need for extraction or other sample preparation steps. The separation is performed in less than 30 s. Very high throughput is possible by operating the assay in multiple channels in parallel. These characteristics make microchip electrophoretic systems a promising technology for the rapid analysis of clinical samples.

Electrophoresis↗
PubMed1996

Antibiotic prophylaxis for patients undergoing transurethral resection of the prostate.

OBJECTIVES: To evaluate the prevention of urinary tract infections (UTIs) after transurethral resection of the prostate (TURP) in a prospective randomized study using a quinolone antibiotic (fleroxacin) to compare the efficacy of: (1) a single oral dose, (2) a single intravenous (IV) dose, and (3) an extended regimen consisting of an initial IV dose followed by oral therapy until removal of the urinary catheter, but for less than 6 days. METHODS: We excluded from study patients who received antimicrobial agents within 48 hours of surgery. Single-dose prophylaxis consisted of 400 mg of fleroxacin given either orally or intravenously. The extended regimen consisted of an initial 400 mg IV dose followed by 400 mg oral each day (patients older than 75 years, or with a creatinine clearance less than 40 mL/min, received 200 mg/day). UTI was defined as clinical evidence of infection plus the presence of more than 10 white blood cells (WBC)/mm3 in any urine specimen plus the presence of more than 10(4) cfu/mL in midstream urine specimens or more than 10(2) cfu/mL in catheter specimens. RESULTS: Prior to TURP, 30% (25/84) of the patients had a urethral catheter in situ and 12% (3/25) of these patients had bacteriuria. Only 1 patient developed a UTI and that was 22 days after a TURP (intergroup comparisons, Fisher's exact test greater than 0.05). There were no instances of urosepsis. CONCLUSIONS: A single oral dose of a fluoroquinolone agent provided optimum prophylaxis for patients undergoing TURP.

Administration, Oral↗
PubMed1995

A total expense reduction plan.

The article depicts strategies for reducing both salary and nonsalary expenses. The importance of productivity monitoring and flexible staffing are key points. Nonsalary reduction techniques include signature controls, review of existing policies and procedures, and cost awareness education.

Cost Allocation↗
PubMed1993

A quantitative study of genital skin flora in male spinal cord-injured outpatients.

Skin flora from the perineum, penis and urethra of 15 adult male outpatients with spinal cord injury (SCI) and neurogenic bladder dysfunction were compared with that of 10 neurologically normal controls. Gram-positive cocci and diphtheroids were the predominant isolates from controls with no enteric organisms recovered except Escherichia coli in four instances. Among SCI patients, in addition to normal Gram-positive flora, one species of Gram-negative rod was isolated from three patients, two species from five patients, three species from three patients, four species from three patients and five species from one individual. Skin isolates included various members of Enterobacteriaceae, Pseudomonas, Acinetobacter and Enterococcus. Average bacterial counts in perineal, penile and urethral cultures from SCI patients were each 1 log greater than in controls. Bacteria were isolated from 12 of 14 urine cultures obtained from SCI patients immediately after collection of skin cultures. Organisms isolated from urine were present in one or more skin sites in every instance. Differences in skin flora between SCI patients and neurologically normal persons may be the result of variables such as antibiotic usage, presence of a condom catheter, skin moisture, urine leakage, pH, skin temperature, personal hygiene and/or neurogenic bowel management.

Adult↗
PubMed1990

Criteria audit of percutaneous nephrolithotomies.

A criteria audit of percutaneous nephrolithotomy management is reported. One hundred consecutive patients who underwent percutaneous stone removal over a 3-year period were examined. An analysis of the cases of this relatively new surgical procedure are presented. The audit demonstrated the surgeons' learning curve, the current standards achieved and changes in patient admission rate. Criteria auditing was used and assessed as a quality assurance activity.

Adolescent↗
PubMed1981

Renal transplantation. 12-Year experience.

The results of cadaveric renal transplantation in one centre over 12 years are reviewed. One hundred and sixty-eight grafts have been performed in 147 recipients. At one year after transplantation, patient survival rate was 86%, and graft survival rate was 63%. Analysis of factors influencing graft survival show that the age of recipients, the lack of blood transfusions, and the use of poorly matched grafts (three to four HLA mismatches against 0 to two mismatches), all had adverse effect on survival. Death was a significant cause of graft loss in patients over the age of 45 years. Patients who had not received blood transfusions, and who received grafts which were mismatched for three to four HLA antigens, did especially badly, graft survival rate at six months being only 24% compared with that of 70% in patients who received blood transfusions.

Adolescent↗
PubMed1978

Immunological studies of testicular tissue in oligozoospermic and azoospermic patients.

Testicular biopsies from 6 oligozoospermic and 12 azoospermic patients were examined histologically and immunohistologically. Evidence of maturation arrest and of Type II allergic reactions involving tubular basement membranes was found in all oligozoospermic patients. No evidence of an immune reaction was found in 9 azoospermic patients with maturation arrest. Unilateral or bilateral germ cell aplasia with evidence of mixed Type II and III or Type III and IV reactions was present in 2 oligozoospermic and 2 azoospermic patients. The findings have been interpreted to indicate that maturation arrest and germ cell aplasia may occasionally be linked in a chain of immunological events, initiated possibly by damage to tubular basement membranes. No correlation was demonstrable between the histological and immunohistological findings and indirect immunofluorescent tests for sperm antibodies. It is suggested that testicular biopsy is a potentially hazardous procedure in the investigation of infertility, and that prepubertal testicular tissues as well as sperm be used as antigens in the immunological investigation of infertility.

Antibodies↗
PubMed1976

The endemic bladder stones of Indonesia---epidemiology and clinical features.

Bladder stone is a relatively common disease of childhood in West Sumatra with an incidence of 8.3/100,000 population per year. We have studied 87 cases with a peak age of onset of 2-4 years and a male/female ratio of 12:1. The majority of these are from poor families with a diet low in protein and phosphate. Diarrhoea is common. The composition of the stones is primarily ammonium acid urate. Patients with sterile urine have shown significantly higher levels of urinary ammonia than controls, and only approximately 50% of patients' urine were infected. This is consistent with excretion of a high acid load, due both to an acidogenic rice diet and diarrhoea, combined with a low level of phosphate. This condition was once endemic in Europe but is now confined to a belt of countries from the Balkans through Asia.

Ammonia↗