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Biomedical subjects

P Stevens

Publications and source records attributed to P Stevens.

At least 127 records · Page 7Linked to original sources
PubMed1976

125I-Radioimmunoassay of amikacin and comparison with a microbioassay.

A radioimmunoassay (RIA) has been developed using 125I-amikacin. Amikacin was iodinated by a modified BOLTON and HUNTER method. Dextran-charcoal was used to separate bound from free drug. The standard curve was linear on a logit-log plot in the range of 0.5 ng to 4 ng amikacin per tube. There was no cross-reactivity of amikacin antisera to the amino-glycosides gentamicin, tobramycin, netilmicin, and sisomicin but a 70% cross-reaction was observed with kanamycin, the compound from which amikacin is synthetically derived. Correlation of the RIA with a microbioassay for the determination of serum amikacin levels in 18 patient samples was excellent (r = 0.94). This new RIA technique is more sensitive, rapid, versatile, and less costly than the RIA using 3H-amikacin, and is far more sensitive and faster than microbioassay.

Amikacin↗
PubMed1975

The flora of renal haemodialysis shunt sites.

During investigations of the microbial flora of the skin over haemodialysis shunt sites it has not proved possible to predict clinical infection by a preceding colonization of the shunt site with a pathogenic organism. The normal non-pathogenic flora of the sites is not specifically related to the flora of other sites on the body though Staphylococcus aureus on a shunt site appeared to be acquired principally from the nose when the shunt was in the arm or from the perineum when the shunt was in the leg. Cimino shunt sites had a greater density of organisms than did Scribner shunt sites; this may be related to the disinfection procedures.

Agar↗
PubMed1975

Synthesis, storage and drug-induced release of atp-8-3h in the perfused bovine adrenal gland.

The perfused bovine adrenal gland was able to take up and phosphorylate adenosine-8-3 H. Stimulation of the gland with carbachol resulted in a simultanious release of catecholamines, adenosine-8-3 H and labelled adenine nucleotides including a small quantity of ATP-3 H. A direct demonstration of the presence of ATP-3 H in isolated chromaffin granules was obrained by modified sucrose density gradient centrifugation. Glands were also perfused with a Ca++-Mg++-free-EDTA medium to inhibit adenosine triphosphatases. Using this medium, significant amounts of ATP-3 H and endogenous ATP were found in the effluent after drug stimulation by either Ba++ of aminophylline. Under Ca++-Mg++-free-EDTA conditions both Ba++ and aminophylline, but not carbachol, stimulated the release of catecholamines, ATP, ATP-3 H with no concomitant increase in total radioactivity. Using normal medium, Ba++ caused the simultaneous release of catecholamines and radioactivity while aminophylline only induced the release of catecholamines. Specific activity measurements of drug-released ATP indicated that the newly synthesized ATP-3 H was being released preferentially during spontaneous activity while the endogenous ATP was preferentially released after either Ba++ or aminophylline-induced secretion.

Adenosine↗
PubMed1975

Functional role of antibody against "core" glycolipid of Enterobacteriaceae.

Antibodies against the "core" glycolipid of Enterobacteriaceae (2-keto, 3-deoxyoctonate-Lipid A) have been associated with protection against the sequelae of gram-negative rod bacteremia. To investigate the nature of this protection, dogs and rabbits were immunized with purified glycolipid prepared by phenol-chloroform-petroleum ether extraction of the "Re" mutant of Salmonella minnesota 595 and opsonophagocytic and bactericidal tests were carried out using lapine peritoneal granulocytes and serum factors. Whereas 1-4 mug/kg of glycolipid i.v. produced hypotension in dogs and 8 mug/kg i.v. was lethal, a rising dosage schedule of immunization with an average total dose of 1 mg/kg produced striking protection against shock and death against challenge with heterologous organisms. 20 control dogs, given approximately 10(10) live, serum-resistant Escherichia coli 0.85:H9 or Serratia marcescens 03 during a continuous intra-arterial pressure transducer recording, showed a drop in mean systolic pressure from 186 (+/- 6 SE) to 101 (+/- 12 SE) MM Hg and a fall in mean diastolic pressure from 118 (+/- 3 SE) to 64 (+/- 8 SE) mm Hg within 60-120 min. Minor pressure changes (average less than 12% of prechallenge levels) were seen in the same number of immunized dogs. In contrast, no significant difference was noted in the bloodstream clearance of these serum-resistant organisms over a period of 4-6 h between immunized and control dogs. Intravascular clearance was greater in animals immunized with the challenged strain or in glycolipid-immunized animals challenged with highly serum-sensitive E. coli 0.14:K7. Antibody against core glycolipid protected against the hemodynamic sequelae of bacillemia, augmented intravascular clearance of serum-sensitive organisms, and abrogated the pyrogenic response to enteric bacilli, but did not enhance clearance of serum-resistant organisms. Although canine and lapine antiserum against core glycolipid passively protected mice against a heterologous challenge, opsonophagocytic and bactericidal activity was at least 100-fold less than type-specific antiserum.

Animals↗
PubMed1975

"Core" glycolipid of enterobacteriaceae: immunofluorescent detection of antigen and antibody.

The Re chemotype mutant of Salmonella minnesota R595 has a cell-wall glycolipid composed principally of 2-keto, 3 deoxyoctonate and Lipid A, which is an antigen widely shared by Enterobacteriaceae. High-titered antiserum against this antigen can be conjugated with fluorescein isothiocyanate for direct detection of this antigen in heterologous bacteria and staining of bacteria in tissue. Alternatively, the indirect immunofluorescence technique can be used for antigen detection on bacterial surfaces and in tissues, and this method can quantitate glycolipid antibody in mammalian sera. The latter may be particularly useful in serologic studies because, although the glycolipid antigen is a surface antigen and purified extracts can be used to coat latex particles, high-titered antisera will not agglutinate bacteria or coated latex particles.

Animals↗
PubMed1975

Radioimmunoassay, acetylating radio-enzymatic assay, and microbioassay of gentamicin: a comparative study.

Gentamicin is an aminoglycoside antibiotic widely used to treat gram-negative bacillary infections. Because it has a low therapeutic index, monitoring of serum levels may help to insure adequacy of dosage and avoid toxicity. Microbiological assays are relatively slow and can be complicated by the presence of other antimicrobials. Radioimmunoassay (RIA) and acetylating radio-enzymatic assay (ARA) are new methods for gentamicin assay which offer the following advantages: rapidity (less than 3 hours); no interference by other antibiotics; RIA is extremely sensitive and ARA is versatile (being useful in the measurement of other aminoglycosides). Correlation coefficients determined by linear regression analysis of assays on 36 patient samples performed in duplicate on 2 different days demonstrated no significant difference in measurement of gentamicin by each of the methods. Factors such as numbers of specimens, cost, and time involved will affect the decision of the method to be applied in individual laboratories.

Acetyl Coenzyme A↗
PubMedDate not supplied

Multicenter HIV and hepatitis B seroprevalence study.

Prior single institutional investigations have found unrecognized HIV seroprevalence in emergency department (ED) patients to range from 0.38% to 4%. A prospective, anonymous study of HIV and hepatitis B (HB) seroprevalence was performed on excess serum of all ED patients over two 48-hour periods in May and August, 1988, from 7 hospitals in the Portland metropolitan area. Demographics were known for 338/444 (76%) of patients. Forty-six percent were male, 85% white, with a median age group of 30-39 years. Ambulance transport, trauma, external blood, presentations requiring ED procedure(s), and acuity resulting in ICU admission were present on 21%, 7%, 10%, 34%, and 14% of patients, respectively. Two of 444 (.45%) patients were HIV +, one previously undiagnosed. Fifty-five of the 444 (12%) and 3 of 444 (0.6%) samples were positive for HBcAB and HBsAG respectively. Risk factor assessment was possible on 180/444 (40%) patients. HBcAB seroprevalence correlated with race (P less than 0.01), IV drug use (P less than 0.0001), and hospital location, (P less than 0.006) but were sensitive in detecting only 14%, 18%, and 38%, respectively, of HBcAB+ patients. HBcAB was not associated with the following factors: sex, area of residence, presence of blood externally, trauma, acuity of illness, ED procedures, or mode of transport. This data strongly support the use of universal body fluid precautions. Hepatitis B poses a significant and distinct risk to all emergency care providers. HB vaccination should be strongly advocated for all ED health care workers (HCWs). Emergency medicine multicenter studies are both desirable and feasible.

Adult↗
PubMedDate not supplied

Intramedullary nailing of femoral fractures in adolescents.

Fifty femoral shaft fractures were treated with reamed, interlocking, intramedullary nails utilizing a greater trochanteric starting point from 1991 through 1998. The 17 girls and 31 boys ranged in age from 10 to 16 years (mean, 13.2 years) at the time of injury. Average follow-up after fracture was 16 months. All fractures united, and the average leg-length discrepancy was 1 mm (range, -10 mm to +11 mm). No patient had angular or rotational deformities. No patients developed osseous necrosis of the femoral head. Despite intramedullary nailing through the greater trochanteric apophysis, articulotrochanteric distance measurements increased only 4.5 mm at the time of last follow-up. No patient developed significant proximal femoral deformity with some follow-up as far as 60 months from the time of surgery. Intramedullary nailing through a trochanteric starting point is a safe, effective method for treating femur fractures in this adolescent age group.

Adolescent↗
PubMedDate not supplied

Long-term efficacy and safety of a low molecular weight heparin in chronic hemodialysis patients. A comparison with standard heparin.

The efficacy and safety of a low molecular weight heparin (LMWH) given as a single predialysis bolus injection was compared to standard heparin (SH) administered with a continuous infusion in a randomized, 6 month, open follow-up study in 70 patients undergoing hemodialysis. No major bleeding or adverse events were encountered during a total of 4,000 dialysis procedures (2,000 with LMWH). Clot formation in the extracorporeal circuit was minimal and comparable between the groups at 4, 13, and 26 weeks after the start of the study. No accumulation of LMWH anticoagulant activity was noted. It is concluded that the use of LMWH is a safe, effective, and less complex alternative to SH.

Blood Coagulation↗
PubMedDate not supplied

Captopril therapy of recurrent nephrolithiasis in a child with cystinuria.

Traditional and current therapies for cystinuria have been difficult for patients, only partially effective, or associated with substantial risk of serious side effects. We present a case of cystinuria that has been managed for 1 year on captopril, with elimination of recurrent nephrolithiasis and with no observable morbidity.

Adolescent↗