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Biomedical subjects

G A Alexander

Publications and source records attributed to G A Alexander.

At least 37 records · Page 2Linked to original sources
PubMed1982

Rapid detection of significant bacteriuria by use of an automated Limulus amoebocyte lysate assay.

Previous studies have demonstrated that significant gram-negative bacteriuria can be detected by using the Limulus amoebocyte lysate test. A series of 580 urine specimens were tested in parallel with the automated MS-2 (Abbott Laboratories) assay and with quantitative urine bacterial cultures. The overall ability of the MS-2 Limulus amoebocyte lysate test to correctly classify urine specimens as containing either greater than or equal to 10(5) organisms or less than 10(5) organisms per ml during a 20-min test period was 92.6%.

Bacteria↗
PubMed1981

Rapid bioassay for chloramphenicol in the presence of other antibiotics.

A simple, rapid bioassay for the measurement of chloramphenicol in serum or cerebrospinal fluid was developed using a multiply antibiotic-resistant strain of Escherichia coli. The agar diffusion system involved the addition of patients' specimens and three standard concentrations of chloramphenicol to 7.5 mm diameter wells cut in agar seeded with the test organism. Assays of chloramphenicol using this system could be read routinely in three to four hours and allowed determinations of levels of 5-60 micrograms/ml. Chloramphenicol could be measured accurately in the presence of a variety of beta-lactam, aminoglycoside, sulfonamide, and tetracycline antimicrobial agents, but not cefoxitin or trimethoprim-sulfamethoxazole. Repetitive assays of sera containing known concentrations of chloramphenicol indicated a coefficient of variation of 8%. Seeded assay plates could be stored at 2-8 degrees C for up to five days prior to use.

Aminoglycosides↗
PubMed1981

Sensitive bioassay for ketoconazole in serum and cerebrospinal fluid.

Ketoconazole is a broad-spectrum antifungal agent which appears promising for treatment of a variety of systemic mycoses. Pharmacokinetic studies are limited due to a lack of readily available methods for quantitation of ketoconazole in serum or cerebrospinal fluid. We developed a rapid, simple bioassay for measurement of ketoconazole alone or in the presence of therapeutic levels of amphotericin B, using an agar diffusion assay incorporating Candida pseudotropicalis. Pairs of 8-mm wells cut in the seeded assay medium were filled with four duplicate ketoconazole standards and duplicate patient specimens. Zones of inhibition were visible after 7 to 8 h of incubation, but were most easily measured after overnight growth. The assay allowed determinations of serum ketoconazole levels as low as 0.3 microgram/ml with a 4.4% coefficient of variation. Thirty-five serum samples from patients receiving the drug were assayed by this method, and the results were compared with the Coccidioides immitis endospore assay. The correlation coefficient between the assays was 0.90. This assay allows any microbiology laboratory to easily and safely determine ketoconazole levels in serum or cerebrospinal fluid.

Amphotericin B↗
PubMed1981

Automation of the Limulus amoebocyte lysate test by using the Abbott MS-2 microbiology system.

A rapid, automated method for the performance of the Limulus amoebocyte lysate endotoxin assay has been developed by using the Abbott MS-2 Microbiology System. This instrument automatically determines sequential changes in the optical density of up to 176 samples at 1- or 5-min increments during a 1-h assay period. Graphic representation of optical density changes can be viewed on a cathode-ray tube or reproduced by using a hard-copy printer. Limulus amoebocyte lysate preparations that were obtained from different commercial producers and that had similar endotoxin sensitivities by the conventional gelation method varied somewhat in reactivity when determinations were based upon rate changes in optical density. Lysates from Associates of Cape Cod, Difco Laboratories, and M. A. Bioproducts were the most readily adaptable to the MS-2 System. Use of the MS-2 system increased the sensitivity of these preparations from 60- to 250-fold, and as little as 1 pg/ml was detected. Adaptation of the MS-2 instrument for this purpose provides an objective, reproducible, automated method for the performance of Limulus amoebocyte lysate tests on a variety of fluids.

Autoanalysis↗
PubMed1981

Advanced skin cancer in Tanzanian albinos: preliminary observations.

Ten cases of advanced squamous cell carcinoma of the skin in albinos, treated by radiotherapy from 1973 to 1979 at the Muhimbili Medical Center of Dar-es-Salaam, have been reviewed. Age, sex, duration of symptoms, anatomic distribution, stage of disease, and treatment are reviewed. The relationship between albinism, sunlight, and skin cancer is discussed and a practical program of prevention is suggested. Advanced carcinoma of skin in albinos may be managed successfully with judicious radiation therapy. Excellent objective responses have been noted. No assessment of long-term control is made due to poor follow-up of patients.

Adolescent↗
PubMed1981

High dose remote afterloading radiotherapy for cervix carcinoma in Tanzania: early results.

From February 1977 through January 1979, 206 patients with histologically confirmed cervix carcinoma were treated with high dose rate afterloading irradiation at the Muhimbili Medical Center of the University of Dar es Salaam, Tanzania. Tribal and regional patterns of disease conform to geographical distributions of referring hospitals. The age at presentation, namely, at over 40 years, is similar to that reported elsewhere from East Africa. Parity among patients ranged from 0 to 14 pregnancies. Vaginal bleeding was the most common symptom in 69 percent of patients. Squamous cell carcinoma was noted in 96 percent of cases. Seventy-six percent of patients had early stage disease. Good initial responses to treatment were recorded in 57 percent of patients. Follow-up of cervical cancer patients is poor. Fifty-six (27 percent) patients were followed 1 to 17 months after treatment. Due to poor follow-up, no definite conclusions are reached regarding late radiation reactions and patient survival. The role or radiotherapy in reducing morbidity, however, is of importance.

Adenocarcinoma↗
PubMed1980

In vitro activities of cefotaxime and moxalactam (LY127935) against Haemophilus influenzae.

The in vitro activities of two new beta-lactam antibiotics, cefotaxime and moxalactam (LY127935), were compared with those of cefamandole, cefoxitin, cefuroxime, and ampicillin against both beta-lactamase-producing and non-beta-lactamase-producing isolates of Haemophilus influenzae. Both cefotaxime and LY127935 were highly active against all isolates irrespective of beta-lactamase production.

Ampicillin↗
PubMed1980

Practical anaerobic broth-disk elution susceptibility test.

A modified broth-disk elution method for routine susceptibility testing of anaerobic bacteria was compared with the proposed reference agar dilution method under study by the National Committee on Clinical Laboratory Standards. The broth-disk elution method used a 24-h test incubation period, Schaedler broth medium supplemented with menadione, and GasPak (BBL Microbiology Systems) incubation. Results obtained by this method compared favorably with carbenicillin, chloramphenicol, clindamycin, and penicillin minimal inhibitory concentrations. The 24-h incubation period led to major discrepancies with tetracycline disk elution tests. This method represents a practical routine procedure for testing of anaerobic bacterial isolates in hospital clinical microbiology laboratories.

Agar↗
PubMed1980

Comparison of moxalactam (LY127935) and cefotaxime against anaerobic bacteria.

The in vitro activities of moxalactam (LY127935 [6059S]) and cefotaxime were compared with those of cefoxitin, cefamandole, cefuroxime, carbenicillin, and penicillin by agar dilution susceptibility testing of a variety of anaerobic bacteria. Moxalactam proved to be the most active agent tested against Bacteroides fragilis and other species of the B. fragilis group. Moxalactam and cefotaxime showed activity similar to the other drugs against the remaining species of Bacteroides, Fusobacterium, Actinomyces, Propionibacterium, and Veillonella. Penicillin was the most effective drug tested against most species of Clostridium, the anaerobic gram-positive cocci, and Eubacterium lentum.

Anaerobiosis↗
PubMed1980

In vitro activities of moxalactam and cefotaxime against aerobic gram-negative bacilli.

The in vitro activities of two new beta-lactam antibiotics, moxalactam disodium (LY 127935) and cefotaxime (HR-756), were compared with cefoxitin, cefamandole, cefuroxime, cephalothin, and, in some instances, carbenicillin, gentamicin, and amikacin against aerobic gram-negative bacilli. Test isolates included normally cephalosporin-resistant members of the Enterobacteriaceae and Pseudomonas spp. and a variety of nonfermentative or oxidase-positive bacteria. Both moxalactam and cefotaxime demonstrated impressive in vitro activities against both groups of microorganisms. The two new drugs were clearly more active than any of the other beta-lactam antibiotics against species of Escherichia, Citrobacter, Enterobacter, Klebsiella, Proteus, Providencia, Pseudomonas, and Serratia. An additive or synergistic effect could also be demonstrated with the majority of Pseudomonas and Serratia isolates when either moxalactam or defotaxime was combined with amikacin.

Aerobiosis↗
PubMed1980

Gentisic acid: a new stabilizer for low tin skeletal imaging agents: concise communication.

In vitro stabilization of low-tin bone-imaging agents has previously been achieved with ascorbic acid. In this study gentisic acid is shown to be an equally effective antioxidant for the (1-hydroxyethylidene) diphosphonate (HEDP) and hydroxymethylenediphosphonate (HMDP) skeletal agents. In vitro studies show less than 2% free sodium [99mTc] pertechnetate at 24 hr with the gentisic acid stabilizer. Studies in guinea pigs at 3 and 24 hr--whether with C-14 or H-3-labeled gentisic acid as stabilizer--show no alteration in the biodistribution of either skeletal imaging agent by the addition of the gentisic acid. Gentisic acid is a safe and effective stabilizer, and clinical studies have shown bioequivalency with ascorbic acid.

Animals↗
PubMed1979

Comparison of Limulus assay, standard plate count, and total coliform count for microbiological assessment of renovated wastewater.

The Limulus endotoxin assay was compared to the standard plate count and total coliform count for assessment of the bacteriological quality of reclaimed wastewater. A total of 48 water samples from an advanced waste treatment plant in Dallas, Tex. were examined by the three techniques. Limulus assays were technically simpler to perform and provided results much sooner than conventional culture methods. However, the endotoxin values did not correlate extremely well with determinations of viable bacterial numbers. This lack of correlation may have been due to alterations in the normal ratio of viable gram-negative cells to endotoxin caused by water reclamation procedures.

Bacteriological Techniques↗
PubMed1979

Particle radiation therapy: requiem or reveille.

The 1960s and 1970s witnessed a surge of many institutions devoted to electron therapy. Currently, many facilities are adding or have added particle types of radiation to their armamentarium against cancer. The authors review the concepts, problems, and potentials of this form of therapy.

Elementary Particles↗
PubMed1978

Oncology fellowship.

Explore the source record for details and available documents.

American Cancer Society↗
PubMed1978

Comparative activities of selected beta-lactam antibiotics against Haemophilus influenzae.

The comparative activities of ampicillin, cefamandole, cefoxitin, cefaclor, and cefatrizine against both beta-lactamase-producing and non-beta-lactamase-producing isolates of Haemophilus influenzae were determined by using an agar dilution susceptibility test procedure. Ampicillin was the most active drug tested against non-beta-lactamase-producing isolates, whereas cefamandole was most active against beta-lactamase-producing strains.

Anti-Bacterial Agents↗
PubMed1978

Modification of cardiopressor and respirogenic effects of doxapram by propranolol.

The respiratory stimulant doxapram hydrochloride has long been shunned in the United States because of a perpetuated fear of the alleged side effects of hypertension and tachycardia with attendant hypermetabolism and increased oxygen consumption. This study reports the results of the administration of doxapram alone, and of doxapram in conjunction with the beta-blocker propranolol on the blood pressure, heart rate, and respiratory rate of 12 healthy unanesthetized volunteer subjects. Results showed an augmentation in blood pressure (especially diastolic), a significant decrease in heart rate, and an unexpected actual increase in respiratory rate in the doxapram/propranolol group. Subtleties of sympathetic balance, as well as proposed future studies are discussed.

Adult↗