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Biomedical subjects

D J Weber

Publications and source records attributed to D J Weber.

At least 181 records · Page 10Linked to original sources
PubMed1985

High-performance liquid chromatographic assay for methylprednisolone and its soluble prodrug esters in dog plasma.

A high-performance liquid chromatographic method with ultraviolet detection (lambda max = 243 nm) has been developed for the simultaneous determination of methylprednisolone (MP) and its water-soluble prodrug esters methylprednisolone hemisuccinate (MPS) and N,N,N'-triethylethylenediamine amide of 6 alpha-methylprednisolone-21-hemisuberate hydrochloride (TMPS) in dog plasma. A reversed-phase liquid chromatographic separation was performed on a Microsorb C8 (3 microns) column equipped with a C8 5-microns guard column. The mobile phase composition was water--acetonitrile--methanol--dimethyloctylamine--acetic acid (65.5:34:0.4:0.04:0.04). The methyl ester of phenethylcarbamate was employed as an internal standard. The chromatographic responses were linear up to 25 micrograms/ml for MP, 70 micrograms/ml for MPS, and 95 micrograms/ml for TMPS. The sensitivity of the assay by ultraviolet detection is approximately 4, 8, and 12 ng/ml of plasma for MP, MPS and TMPS, respectively. The assay variability in terms of 95% confidence limit for each steroid is less than 4.5%. Plasma concentration--time curves are reported for MP, MPS, and TMPS after intravenous administration of MPS and TMPS equivalent to 3, 10 and 30 mg MP per kg body weight of dog. The assay methodology is simple, selective and reproducible for the quantitative determination of MP, MPS and TMPS in dog plasma.

Animals↗
PubMed1985

Cryptosporidiosis in immunocompetent patients.

The intestinal protozoan cryptosporidium is known to cause diarrhea in immunocompromised patients, but few cases have been reported in detail in immunocompetent persons. During a 12-month period, we identified cryptosporidium in the stools of 43 immunocompetent patients. The numbers of cases were increased in those under 4 years old and in those from 30 to 39 years old. Of 30 index cases, 23 (77 per cent) were diagnosed in the late summer or the fall. Fifteen of the 43 patients (35 per cent) had other gastrointestinal pathogens, of which only Giardia lamblia was statistically associated with cryptosporidium. In the 28 patients in whom other gastrointestinal pathogens were not identified, the clinical manifestations were predominantly watery, nonbloody diarrhea and, less commonly, abdominal discomfort, anorexia, fever, nausea, and weight loss. The infection was self-limited in all 43 patients. Clustering of cases occurred in a day-care center and in two families. These clinical observations confirm worldwide findings and suggest that cryptosporidium is a relatively common nonviral cause of self-limited diarrhea in immunocompetent persons in the northeastern United States.

Adolescent↗
PubMed1984

High-performance liquid chromatographic assay of pirlimycin in human serum and urine using 9-fluorenylmethylchloroformate.

A reversed-phase high-performance liquid chromatographic (HPLC) assay method has been developed for determining pirlimycin in human serum and urine. The method involves chloroform extraction of pirlimycin free base followed by derivatization with 9-fluorenylmethylchloroformate to form a carbamate ester. The reaction is rapid, reproducible, and quantitative. 9-Fluorenylmethylchloroformate reacts with amines to form derivatives sensitive to both ultraviolet and fluorescence detection. Human serum and urine samples following 50-mg and 500-mg single oral doses of pirlimycin were analyzed. The samples were chromatographed on an RP-18 Spherisorb 5-micron, 250 X 4.6 mm I.D. reversed-phase HPLC column. The eluent for the serum assay was acetonitrile-water (58:42) containing 0.02% acetic acid, and for the urine assay was acetonitrile-methanol-tetrahydrofuran-water (48:2:1:49). Fluoranthene was used as an internal standard. The assay sensitivity by ultraviolet detection (lambda max = 264) was about 5 ng/ml and by fluorescence detection (lambda excitation = 270 nm, lambda emission = 300 nm) was 0.1 ng/ml. Statistical analysis indicates an average drug recovery of 101 +/- 4.2% from serum and 102.0 +/- 2.62% from urine.

Chemical Phenomena↗
PubMed1984

Pasteurella multocida infections. Report of 34 cases and review of the literature.

Pasteurella multocida, a small, gram-negative coccobacillus , is part of the normal oral flora of many animals, including the dog and cat. P. multocida is the etiologic agent in a variety of infectious disease syndromes. We have reported 34 cases of infection caused by P. multocida and have reviewed the English literature. P. multocida infections may be divided into three broad groups: 1. Infections resulting from animal bites and scratches : The most common infections caused by P. multocida are local wound infections following animal bites or scratches . Cats are the source of infection in 60 to 80% of cases and dogs in the great majority of the remainder. Local infections are characterized by the rapid appearance of erythema, warmth, tenderness, and frequently purulent drainage. The most common local complications are abscess formation and tenosynovitis. Serious local complications include septic arthritis proximal to bites or scratches , osteomyelitis resulting from direct inoculation or extension of cellulitis, and the combination of septic arthritis and osteomyelitis, most commonly involving a finger or hand after a cat bite. 2. Isolation of P. multocida from the respiratory tract: The isolation of P. multocida from the respiratory tract must be interpreted differently than its isolation from other systemic sites. Most commonly P. multocida found in the respiratory tract is a commensal organism in patients with underlying pulmonary disease, but serious respiratory tract infections including pneumonia, empyema, and lung abscesses may develop. Most patients with respiratory tract colonization or infection have a history of animal exposure. 3. Other systemic infections: P. multocida is recognized as a pathogen in a variety of systemic infections including bacteremia, meningitis, brain abscess, spontaneous bacterial peritonitis, and intra-abdominal abscess. P. multocida often acts as an opportunistic pathogen with a predilection for causing bacteremia in patients with liver dysfunction, septic arthritis in damaged joints, meningitis in the very young or elderly, and pulmonary colonization or invasion in patients with underlying respiratory tract abnormalities.(ABSTRACT TRUNCATED AT 400 WORDS)

Abscess↗
PubMed1981

Hyperthyroidism and propylthiouracil-induced agranulocytosis during chronic lithium carbonate therapy.

The authors describe the case of a 49-year-old woman who developed a goiter, mild symptoms of hyperthyroidism, and grossly elevated thyroid function tests after 2 years of treatment with lithium carbonate. Thyroid microsomal autoantibodies were also present. She was retreated with propylthiouracil and improved, but within 3 months she developed agranulocytosis. Propylthiouracil was discontinued, and the patient was treated with antibiotics and recovered. She was then given 131I to control her hyperthyroidism. The case is an example of the rare association of hyperthyroidism with lithium, which usually suppresses thyroid function, and demonstrates that lithium carbonate cannot prevent agranulocytosis caused by propylthiouracil.

Agranulocytosis↗
PubMed1977

Synchronous sporulation during idiophase development in surface cultures of Rhizopus arrhizus (Fischer).

A method to obtain synchronous sporulation during idiophase development in liquid surface cultures of Rhizopus arrhizus Fischer in described and evaluated for use in studying metabolism associated with asexual sporulation. In this system growth and sporulation are effectively separated. The respiratory pattern indicates three metabolic phases. The first is associated with spore germination; the second, trophophase, with growth; and the third, idiophase, with sporulation. Synchronous sporulation and the occurrence of distinct metabolic phases are taken as indications of fairly uniform cell development in the surface cultures. A photographic method of estimating large numbers of fruiting structures on semisolid medium is also described.

Carbon Dioxide↗
PubMed1976

High-pressure liquid chromatographic analysis of tolbutamide in serum.

A high-pressure liquid chromatographic (HPLC) analysis of tolbutamide in serum is described. The assay requires only 1 ml of serum and is capable of measuring as little as 2 mug of tolbutamide. The metabolites of tolbutamide do not interfere in the assay. Human serum samples, taken after a 1-g oral dose of tolbutamide, were analyzed by the HPLC and an existing GLC procedure, and the results are compared.

Chromatography, Gas↗