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Biomedical subjects

J Bennett

Publications and source records attributed to J Bennett.

At least 307 records · Page 17Linked to original sources
PubMed1985

Single-dose pharmacokinetic and pharmacodynamic comparison of polymer-matrix (Slow Trasicor) and Oros dosage forms of oxprenolol in healthy volunteers.

Oxprenolol was administered in single doses by mouth to healthy volunteers either in a polymer-matrix slow-release formulation (Slow Trasicor) or in osmotic drug-delivery systems (oxprenolol Oros). Plasma oxprenolol concentrations and heart rates after exercise were measured. Plasma concentrations of the drug were maximal at 3 h but negligible at 24 h after administration of Slow Trasicor. Following ingestion of the Oros systems measurable concentrations were maintained throughout 24 h. Significant reduction of exercise-induced tachycardia persisted for 24 h after administration of oxprenolol Oros. With Slow Trasicor heart rate responses had returned to baseline values by this time. The osmotic drug-delivery systems appear to sustain significant beta-adrenoceptor blockade for 24 h after a single oral dose.

Adult↗
PubMed1984

Specific thromboxane synthetase inhibition and albumin excretion rate in insulin-dependent diabetes.

Albumin excretion rates (AER) were measured in 30 insulin-dependent diabetics during a 16-week double-blind, randomised, placebo-controlled study of the specific thromboxane synthetase inhibitor UK-38,485.6 of 15 subjects in the active group had microalbuminuria (defined as mean pretreatment AER 20-150 micrograms/min); in these patients AER fell from 32 +/- 3 micrograms/min to 11 +/- 1 micrograms/min at 8 weeks and 9 +/- 1 micrograms/min at 16 weeks. The AER rose again (to 29 +/- 8 micrograms/min) within 12 weeks of stopping the drug. There was no significant change in the 10 patients with microalbuminuria who received placebo. There was a strong correlation between change from baseline values and the baseline values themselves in the active, but not in the placebo group, and the change from baseline differed significantly between the two groups. There was no change in glycosylated haemoglobin or mean blood glucose levels during the study. In a separate study UK-38,485 caused significant suppression of thromboxane B2 synthesis in diabetic and non-diabetic subjects.

Adult↗
PubMed1984

Differential regulation of the accumulation of the light-harvesting chlorophyll a/b complex and ribulose bisphosphate carboxylase/oxygenase in greening pea leaves.

The photoregulation of chloroplast development in pea leaves has been studied by reference to three polypeptides and their mRNAs. The polypeptides were the large subunit (LSU) and the small subunit (SSU) of ribulose 1,5-bisphosphate carboxylase/oxygenase (RUBISCO), and the light-harvesting chlorophyll a/b protein (LHCP). The polypeptides were assayed by a sensitive radioimmune assay, and the mRNAs were assayed by hybridization to cloned DNA probes. LSU, LSU mRNA, and LHCP mRNA were detectable in etiolated seedlings but LHCP, SSU, and SSU mRNA were at or below the limit of detection. During the first 48 hr of de-etiolation under continuous white light, the mRNAs for LSU, SSU, and LHCP increased in concentration per apical bud by about 40-fold, at least 200-fold, and about 25-fold, respectively, while the total RNA content per apical bud increased only 3.5-fold. In the same period, the LSU, SSU, and LHCP contents per bud increased at least 60-, 100-, and 200-fold, respectively. The LHCP increased steadily in concentration during de-etiolation, whereas the accumulation LSU, SSU, and SSU mRNA showed a 24-hr lag. The accumulation of SSU, SSU mRNA, and LHCP mRNA showed classical red/far-red reversibility, indicating the involvement of phytochrome in the regulatory mechanism. LSU and LSU mRNA were induced equally well by red and far-red light. The LHCP failed to accumulate except under continuous illumination. These results indicate that the accumulation of SSU is controlled largely through the steady-state level of its mRNA, which is in turn almost totally dependent on light as an inducer and on phytochrome as one of the photoreceptors. The accumulation of LSU is largely but not totally determined by the level of its mRNA, which appears to be under strong photoregulation, which has yet to be shown to involve phytochrome. Phytochrome is involved in the regulation of LHCP mRNA levels but substantial levels of the mRNA also occur in the dark. LHCP accumulation is not primarily governed by the levels of LHCP mRNA but by posttranslational stabilization in which chlorophyll synthesis plays a necessary but not sufficient role.

Chlorophyll↗
PubMed1984

Early mouse embryos exhibit strain variation in radiation-induced sister-chromatid exchange: relationship with DNA repair.

Although mature mammalian sperm are incapable of DNA repair, repair of damaged sperm DNA can occur after fertilization, as the sperm head decondenses and forms the male pronucleus. To quantify the cytogenetic effects of damage to sperm DNA we adapted the sister-chromatid exchange (SCE) test for use in early mouse embryos. After ultraviolet (UV) irradiation of sperm, eggs were fertilized in vitro and cultured for 2 cell cycles in medium containing fluorodeoxyuridine and bromodeoxyuridine; chromosomes were then prepared for SCE analysis. We found that UV-induced SCEs could be detected at the second cleavage division, and that eggs of different strains showed different frequencies of SCEs when fertilized by damaged sperm of a single strain. These results may indicate strain-specific differences in DNA repair of UV-induced DNA lesions by the early mouse embryo.

Animals↗
PubMed1984

Use of inhaled calcium channel blocking agents in the treatment of asthma.

The inhalation of drugs that are active in the respiratory tract offers the ideal route of administration, since it results in the rapid delivery of appropriate concentrations with a much reduced risk of systemic adverse effects: Problems with regard to poor absorption from the gastrointestinal tract (sodium cromoglycate) or substantial effect on liver metabolism (verapamil) can be avoided. Certain drugs such as antihistamines and ketotifen may be more effective administered by inhalation since high concentrations with reduced unwanted effects can be achieved on the bronchial surface where, in allergic asthma, the critical initial interaction between sensitized mast cells (mucosal?) and allergen with subsequent mediator release occurs. Indeed inhaled verapamil has been shown to be effective in animal models of asthma but not in man. Systemically administered nifedipine gives partial and variable protection against induced asthma in man and its efficacy (with reduced cardiovascular effects) may well be improved by inhalation.

Aerosols↗
PubMed1984

Surface membrane heterogeneity among human mononuclear phagocytes.

Considerable information has been accumulated about the functional and metabolic differences that exist among human mononuclear phagocytes isolated from different anatomic sites. This heterogeneity may reflect the influence of environmental factors that stimulate circulating monocytes to differentiate in a distinctive manner, or may suggest the existence of predetermined subsets of macrophage precursors. The present study was designed to evaluate macrophage diversity at the membrane level by defining the expression of antigenic determinants on the surface of these cells. The expression of two new membrane differentiation antigens, BMM1 and PAM1, and of Mo1 and Mo2 were evaluated on blood monocytes, macrophages derived from cultured monocytes, breast milk macrophages (BMM), pulmonary alveolar macrophages (PAM), and peritoneal macrophages. Anti-BMM1 is a mouse IgG2a monoclonal antibody obtained by immunization with breast milk cells that recognizes an antigen expressed only on BMM but not on blood monocytes (or any other circulating cells), PAM, and peritoneal macrophages. BMM1 expression is also seen on HL60 promyelocytes induced toward macrophage differentiation by lymphokines but not by phorbol diester. Anti-PAM1, an IgG1 monoclonal antibody raised by immunization with PAM, reacts with an antigen found only on PAM. Blood monocytes, BMM, and peritoneal macrophages all share the previously described differentiation antigens, Mo1 and Mo2 (as well as Ia), whereas these markers are not found on PAM. BMM1 is associated with a two subunit surface protein of 46 and 40 Kd, and PAM1 resides on a 200 Kd polypeptide. The appearance of new antigens during differentiation (BMM1 on milk macrophages and PAM1 on PAM) and the disappearance of antigens more common to the macrophage lineage (absence of Mo1 and Mo2 on alveolar macrophages) indicate a significant heterogeneity at the membrane level among phagocytes obtained from different anatomic sites (but arising from a common myeloid precursor). The functional relevance of these structures selectively expressed by BMM and PAM is the object of further investigation.

Antibodies, Monoclonal↗
PubMed1984

Treatment of myeloid blastic crisis of chronic myelogenous leukemia.

Patients with myeloid blastic crisis of chronic myelogenous leukemia were treated by chemotherapy or by autologous hematopoietic reconstitution after aggressive chemotherapy. Chemotherapy alone failed to produce a second chronic phase. Autologous transplantation resulted in the establishment of a second chronic phase in two of ten patients treated with a four-drug regimen, while treatment with high-dose cytarabine with or without busulfan resulted in the establishment of a second chronic phase in three of six patients and the return of normal hematopoiesis in a fourth. Consolidation chemotherapy appeared to be beneficial.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1983

Quantitation of ketoconazole in biological fluids using high-performance liquid chromatography.

A rapid, specific procedure is described for the quantitation of ketoconazole in biological fluids using high-performance liquid chromatography (HPLC). The procedure involves sample preparation using a reverse-phase C-18 cartridge prior to chromatography and quantitation using peak height ratios (UV absorbance detection, 231 nm) of ketoconazole to the internal standard, phenothiazine. A sensitivity of 0.2 micrograms/ml was achieved using a 0.5-ml sample. The mean recovery was 86.2%, and overall coefficient of variation of the procedure was 7.1%. This procedure has been used to determine ketoconazole levels in human serum, plasma, CSF, and synovial fluid. A comparison with a microbiological assay is presented, and adaptability of this procedure to quantitation by fluorescence to increase the sensitivity fivefold is discussed.

Biological Assay↗
PubMed1983

Effect of alcohol on propylthiouracil disposition.

We examined the effect of ethanol on propylthiouracil (PTU) disposition in normal subjects and a rabbit. The drug is metabolized by conjugation. In six normal subjects 19.2 gm oral ethanol, taken either with or two hr after 300 mg PTU, did not change maximum concentration, time to maximum concentration, or total or free AUC of PTU. Pretreatment with ethanol and supplementation to keep blood ethanol concentration above 800 mg/l for 8 hr also did not alter PTU disposition. In the rabbit, the infusion of ethanol (8.81 mg/min) 4 hr after the beginning of an intravenous infusion of PTU 0.05 mg/min did not alter the plasma concentration profile. These results indicate that short-term ethanol dosing does not affect PTU disposition and therefore dosage adjustment is not necessary in patients who drink alcohol.

Administration, Oral↗