Pharmacokinetics of metronidazole in patients with alcoholic liver disease

The pharmacokinetics of metronidazole was evaluated in eight patients with alcoholic liver disease. Metronidazole (7.5 mg/kg) was administered to each patient intravenously. Serial blood samples were obtained after the dose. Serum metronidazole concentrations were determined by high-performance liquid chromatography. The following pharmacokinetic parameters (mean +/- standard deviations) were obtained: half-life, 18.31 +/- 6.06 h; elimination rate constant, 0.042 +/- 0.013 h-1; volume of distribution, 0.77 +/- 0.16 liters/kg; and total body clearance, 0.51 +/- 0.11 ml/min per kg. Compared with subjects with normal liver function, patients with liver disease showed a reduction in drug elimination rate and total body clearance. The half-life of metronizadole in serum and volume of distribution were increased. Large variations of these parameters were also observed among the patients. On the basis of these observations, a reduced dose of metronidazole should be given to patients with alcoholic liver disease to avoid accumulation of metronidazole and its metabolites. Monitoring of drug concentration in serum may also be necessary to optimize therapy.

Structure-activity relationships of 6-(heterocyclyl)-methylene penam sulfones; a new class of beta-lactamase inhibitors

6-(Heterocyclyl)methylene penam sulfones (1) are effective beta-lactamase inhibitors and potent ampicillin and cefazolin potentiators against both Gram-positive and Gram-negative beta-lactamase producing bacteria. Several of these analogs having a pi-deficient 2-heteroaryl substituent attached to the C6-methylene position showed better inhibitory activity than clavulanic acid, Ro 15-1903, 6 beta-bromopenicillanic acid, and sulbactam against a variety of beta-lactamases. The compounds were devoid of any antibacterial activity, but in combination with ampicillin or cefazolin, exhibited synergistic activity at least equal to clavulanic acid, Ro 15-1903, 6 beta-bromopenicillanic acid or sulbactam against beta-lactamase producing strains. Structure-activity relationships for a number of compounds are described. The structure-activity relationships can be rationalized by an enzyme inhibition mechanism which we have previously proposed on the basis of methanolysis of 6-(2-pyridyl)methylene penam sulfone (1a). Two synthetic routes to prepare compounds of structural type 1 via either a Wittig reaction or an aldol condensation are reported. beta-Lactamase inhibition and MIC data are presented.

Regional myocardial perfusion of cardioplegic solutions

We compared the regional myocardial perfusion of blood cardioplegic solution (BCP) and crystalloid cardioplegic solution (CCP) in 14 mongrel dogs. Cardiopulmonary bypass was established at 28 degrees C, and a hydraulic occluder was placed around the proximal left anterior descending (LAD) coronary artery. In group 1 (N = 7) collateral coronary arteries were ligated; in group 2 (N = 7) collateral coronary arteries were left in situ. After the aorta was clamped, BCP and CCP were alternately perfused at 200 ml/min. The occluder was inflated to produce moderate, severe, and critical LAD stenosis, and regional perfusion was measured by xenon-133 washout with the Silicon Avalanche Radiation Detector. BCP infusion produced a consistently higher aortic pressure, but CCP flow was better than BCP flow under all conditions, particularly without coronary collaterals (p less than .05). Regional myocardial perfusion of CCP is superior to BCP.

Isolation and characterization of the structural gene for secreted acid phosphatase from Schizosaccharomyces pombe

The Schizosaccharomyces pombe acid phosphatase structural gene (PHO 1) was isolated by complementation of an S. pombe acid phosphatase mutant with a wild type S. pombe DNA recombinant plasmid library. Northern analysis indicates that acid phosphatase is encoded by a 1.4-kilobase mRNA of which approximately 100 bases are 3'-poly(A). The gene contains no introns and the 3' and 5' untranslated regions are short. According to DNA and amino acid sequence data, the S. pombe acid phosphatase has a molecular weight of 50,600. An 18-amino acid sequence at the N terminus was found that is similar to previously identified signal peptides in other eukaryotic secretory proteins. This signal peptide is apparently removed during secretion, since it is absent in the mature secreted acid phosphatase. The gene can be induced 2--3-fold by starvation for phosphate. The signals required for this induction are contained on the isolated DNA clone. Although the gene can be expressed in Saccharomyces cerevisiae, secretion is abnormal.

Evaluation of a potential drug interaction between sucralfate and aspirin

Recent studies have demonstrated a cytoprotective effect of sucralfate on gastric mucosa in patients receiving aspirin. The potential drug interaction between sucralfate and aspirin was evaluated in a randomized crossover manner in 12 healthy men. Subjects were initially given a single dose of aspirin alone or in combination with sucralfate for 2 days. The drug dosing schedule was then reversed after 1 week. Sixteen blood samples were drawn after each aspirin dose for HPLC assay of aspirin and its metabolites. Pharmacokinetic parameters were calculated for aspirin, salicylic acid, and salicyluric acid. None of these parameters demonstrated any statistically significant differences between the two treatment groups. The combined use of sucralfate and aspirin is therefore not likely to result in a clinically significant pharmacokinetic drug interaction. The systemic therapeutic effect of aspirin is not expected to be altered when sucralfate is used concurrently in patients receiving chronic aspirin therapy.

Hemodialysis clearance of metronidazole and its metabolites

Metronidazole is now being used with increasing frequency for various infectious conditions in patients with renal failure. It is commonly administered to septic patients who have developed acute renal failure requiring hemodialysis. The hemodialysis clearances of metronidazole and its metabolites were evaluated in nine renal failure patients on maintenance hemodialysis. The mean +/- standard deviation clearance and the extraction ratio were 106.9 +/- 16.3 ml/min and 0.65 +/- 0.08, respectively, when regenerated cellulose dialysis membrane was used. The clearance and the extraction ratio with the use of cuprophan membrane were 72.1 +/- 17.3 ml/min and 0.44 +/- 0.12, respectively. The clearances and extraction ratios for the metabolites were similar to those of the parent drug. For both metronidazole and the hydroxy metabolite, the clearance and the extraction ratio demonstrated a statistically significant difference between the regenerated cellulose membrane and the cuprophan membrane. In summary, metronidazole and its metabolites were found to be highly dialyzable with different clearances depending on the specific type of membrane used. However, owing to the relatively wide therapeutic index of the drug, dosage supplementation may be necessary only in seriously ill patients to ensure therapeutic effect.

Selective alkylation of carcinogenic 9-anthryloxirane at the N-3 position of adenine in DNA

Carcinogenic 9-anthryloxirane binds covalently to calf thymus DNA and poly(dA-dT). Application of the technique for DNA sequence determination shows that acid cleavage of the modified DNA frees approximately half of the anthryl groups from the DNA. HPLC analysis indicates that an adenine adduct and the glycol derived from 9-anthryloxirane are the major acid-labile products. Spectroscopic analyses establish that the adenine adduct is the N-3 adduct of 9-anthryloxirane to adenine. Similar analyses of modified poly(dA-dT) indicate that the binding of 9-anthryloxirane takes place selectively at the N-3 position of adenine. The significance of this finding is briefly discussed.

Comparison of mutagen accumulation in 3 estuarine species using the salmonella/microsome activation system

3 Estuarine organisms- oysters (Crassostrea virginica), sea squirts (Mogulla sp.), and shrimp (Peneaus sp.)-were examined for Ames test detectable levels of mutagens. Whole-tissue extracts of these organisms were made and tested using S. Typhimurium strains TA98, TA100, TA1535, TA1537 and TA1538, with and without S9 activation. Positive results were obtained with sea squirts and shrimp extracts. Activation was not necessary to show activity. Toxicity was encountered with oyster extracts. Histidine, a possible source of false positives, was eliminated from shrimp extracts using XAD-2 resin and thick-layer chromatography.

Starch depletion and sugars in developing cotton leaves

Cotton plants (cv. Coker 100) were exposed to a 14-hour dark period. Starch degradation occurred with no accumulation of sugars due mainly to translocation. Considerable amounts of starch degradation products however were detected from leaves after phloem transport was blocked. A minor component (10 to 25% of total starch) with a linear structure, amylose, was preferentially degraded, whereas the major multiple-branched component (about 80%), amylopectin, showed an increasing resistance to degradation with leaf age. This relationship was also shown by the decreasing iodine-binding capacity of unit starch with increasing leaf age. The structural resistance of amylopectin to enzymic dark degradation was one of the barriers to starch dissolution in cotton.

Isolation and purification of leaf starch components

A procedure was developed for the separation and purification of amylose and amylopectin isolated from cotton leaves. Cotton leaves were homogenized in 0.02 molar phosphate buffer at pH 7.0 containing HgCl(2) plus toluene. Crude starch granules were collected by centrifugation and partially purified by treating with acetone and toluene. The starch granules were then dispersed in dimethylsulfoxide and precipitated with ethyl alcohol. The precipitate was suspended in boiling water. Amylose was separated from amylopectin and cell wall particles on a Sepharose 2B column and further purified with thymol and butanol. Amylopectin was then separated from the colloidal cell wall contaminants by its specific interaction with concanavalin A. Purities of starch components were verified by specific biochemical and enzymic tests in addition to their iodine-binding capacity. This procedure should also be suitable for purification of starch components from other plant sources.

Free vascularised bone graft using microvascular technique

The authors investigated 212 dried human fibulae to find out the length, the circumference and the entry points of nutrient artery to the fibula. Angiography of six freshly amputated limbs was studied to show the relationship of the posterior tibial artery and peroneal artery. Seven clinical cases of free vascularised fibula graft are reported. The length of the fibula graft varies from 10 cm to 20 cm. A postoperative 113M-In EDTMP examination revealed the blood supply to the grafted fibula was adequate. The bony healing and functional restoration of the extremities proved to be satisfactory.

Starch and its component ratio in developing cotton leaves

During cotton leaf development, starch accumulation was characterized by an initial rise to a maximum at the second to the fourth leaf from the apex. Then, starch content progressively decreased with leaf age. Starch accumulation was inversely related to the ratio of amylopectin to amylose. Differences between leaves in this ratio resulted from variations in both amylose and amylopectin levels. Fluctuations in amylose levels were more extreme than those of amylopectin.During the diurnal cycle, amylopectin was accumulated more than amylose in both young and old leaves during the day. During the night, amylopectin was degraded more than amylose in young leaves and vice versa in older leaves. The rate of change of the amylopectin to amylose ratio during the day was consistently higher than that during the night.

Effect of estrogen on gene expression in the chick oviduct. In vitro transcription of the ovalbumin gene

Problems involved in using the Hg-nucleotide technique for in vitro chromatin transcription are 2-fold. First, Escherichia coli RNA polymerase can utilize endogenous RNA as template and synthesize complementary sequences which remain base-paired to the template, thereby allowing it to bind to the SH-Sepharose column and copurify with the newly synthesized Hg-RNA. Second, non-mercurated endogenous RNA can bind to the SH-Sepharose through aggregation with Hg-RNA and thus be retained in the final RNA preparation. These two problems associated with the Hg-nucleotide technique can be minimized by modifying the conditions for RNA synthesis and SH-Sepharose chromatography. Using the modified procedure the Hg-nucleotide and SH-Sepharose technique can remove more than 90% of endogenous RNA contaminants. In order to directly demonstrate that the mRNAov sequences detected in vitro result from de novo transcription of oviduct chromatin, experiments were carried out which show that the hybridizable RNA sequences contain the Hg element and that the synthesis of these RNA sequences is sensitive to low concentrations of actinomycin D. These combined results strongly suggest that the majority of mRNAov sequences detected by hybridization to cDNAov is indeed due to DNA-dependent RNA synthesis by E. coli RNA polymerase and not due to an artifact of endogenous RNA contamination. This observation was further supported by data obtained using a filter hybridization method which measures directly the mRNAov sequences present in [3H]RNA synthesized from chromatin. The 3H-labeled ovalbumin messenger RNA was assayed by hybridization to cloned pOV230 DNA containing the ovalbumin structural gene sequence. With this modified Hg-nucleotide-SH-Sepharose technique and filter hybridization technique, we have restudied the in vitro transcription of the ovalbumin gene from chromatins isolated at different stages of hormone-induced oviduct development. The results are in agreement with our previous findings which suggest that the primary regulation of ovalbumin synthesis by steroid hormones occurs at the transcriptional level.

Carbon dioxide and senescence in cotton plants

Glandless cotton plants (Gossypium hirsutum L. cv. Coker 100) were subjected to the influence of high CO(2)-bicarbonate. The content of protein decreased with no accompanying increase in its degraded products. The decrease in protein was correlated with the low content of chlorophyll and also with the reduced activity of carbonic anhydrase. The initiation of these correlations coincided with the time when the control leaves contained the highest enzyme activity during leaf growth. The high concentration of bicarbonate directly restricted the rate of photophosphorylation and that of the Hill reaction in isolated chloroplasts. The amount of ATP in leaves treated in vivo also diminished. High CO(2) as bicarbonate, however, did not directly inhibit the activity of carbonic anhydrase in vitro.

Effect of fluoride on ribosomes and ribonuclease from corn roots

A study was made of ribosomes and ribonuclease in the roots of corn seedlings aged by fluoride. Fluoride induced a reduction of ribosome content in which a decrease in polysome level was accompanied by an increase in number and concentration of monosomes and subunits combined. Fluoride increased the specific activity of ribonuclease, probably associated with ribosomal protein. This enhanced activity was likely due to enzyme activation caused by fluoride. Sucrose density gradient analyses demonstrated that ribosome fractions contained a mixture of heterogeneous RNA components.