Excessive use of vancomycin: a successful intervention strategy at an academic medical center

The project goal was to decrease excessive vancomycin use. Interventions included an educational chart note the first day of therapy, followed by pharmacists discussing the need for continued therapy with patients' physicians. Empirical vancomycin use improved from 20% to 90% compliance with guidelines within 6 months of the intervention.

The impact of counselling on HIV-infected women in Zimbabwe

The objective of this study was to examine the impact of counselling provided for HIV-infected women in Zimbabwe. Qualitative research was used for data collection. In total, 44 women were heard; most were members of an HIV support group. Doctors and nurses play an important role in the first counselling session, because tests to diagnose HIV-infection are done in the hospital. Interviewed women mention slow disclosure of status as the most comforting way to hear the news. The HIV-infected women experience strong emotions directly after diagnosis. Counselling at this moment is of major importance to reduce fear and can prevent suicide. Women should be prevented from discovering their status on their own. Counselling given once is found not to be effective. First, if only one counselling session is given, the women may not hear or remember all that is said. Second, in case of depression, access to counselling is important and it appears that periods of depression return frequently. Support groups play an important role in providing this continuous counselling. Another advantage of the counselling provided by HIV-positive women of a support group is that the counsellors function as examples.

Peroxisome proliferators increase the formation of BPDE-DNA adducts in isolated rat hepatocytes

Peroxisome proliferators are known to modulate the activity of xenobiotic-metabolising enzymes, including glutathione S-transferase (GST) and cytochrome P-450 (CYP). In this study the effect of peroxisome proliferators silvex and di(2-ethylhexyl)phthalate (DEHP) on the formation of (+)-anti-benzo(a)pyrene -7,8-dihydrodiol-9,10-epoxide (BPDE)-DNA adducts from a proximate mutagen and carcinogen (-)-transbenzo(a)pyrene-7,8-dihydrodiol (BPDD) has been investigated. Rat CYP1A1 metabolises BPDD to mutagenic BPDE, which may form DNA adducts or, alternatively, be detoxified by hydrolysis or glutathione conjugation. In this experiment the formation of BPDE-DNA adducts was significantly increased in hepatocytes isolated from all silvex treated rats and two out of four DEHP treated rats (14 day treatment). The activity of CYP1A1 was increased whereas GST was reduced by the peroxisome proliferator silvex. These changes were more significant than those induced by DEHP. We have hypothesised that the formation of BPDE-DNA adducts was primarily due to the increased BPDD activation to BPDE versus reduced detoxication of BPDE. Other hepatic changes induced by the peroxisome proliferators, e.g. peroxisome proliferation per se and increased mitotic activity of the liver could have an effect on the outcome of BPDD exposure.

Perceptions of children and community members concerning the circumstances of orphans in rural Zimbabwe

Focus group discussions and interviews were held with 40 orphans, 25 caretakers and 33 other community workers from a rural area near Mutare, Zimbabwe. Orphan concerns included feeling different from other children, stress, stigmatization, exploitation, schooling, lack of visits and neglect of support responsibilities by relatives. Many community members, while recognizing their limitations due to poverty, were already actively helping orphans and caretakers. Extended family networks are the primary resource for orphans, though some relatives exploit orphans or fail to fulfil their responsibilities. Interventions are suggested which support community coping mechanisms by strengthening the capacities of families to care for orphans. Outside organizations can develop partnerships with community groups, helping them to respond to the impact of AIDS, by building upon existing concern for orphan families. They can help affected communities to develop orphan support activities which encourage caring responses by community leaders and relatives and which discourage property-grabbing and orphan neglect. Material support channelled through community groups to destitute families at critical times can strengthen family coping mechanisms. Income-generating activities should build upon communities' existing capabilities and benefit the most vulnerable orphan households. Some communities are responding to the AIDS disaster by adaptations to cope with devastating changes taking place in their communities.

Peroxisome proliferator nafenopin potentiated cytotoxicity and genotoxicity of cyclophosphamide in the liver and bone marrow cells

Peroxisome proliferators are ubiquitous rodent hepatocarcinogens, known to modulate the activities of xenobiotic-metabolising enzymes such as glutathione S-transferases (GST) and mixed-function oxidase (cytochrome P-450). In addition these compounds induce pleiotropic changes in the liver of rodents even after a short-term treatment. It has been hypothesised that the enzymatic and cellular changes induced by peroxisome proliferators may alter the toxicity of other compounds activated by cytochrome P-450 and detoxified by GST isoenzymes. The effect of nafenopin-induced changes in the liver of rats on the toxicity of an anti-cancer drug cyclophosphamide was studied using cyto- and geno-toxicity parameters in the liver and bone marrow cells. The administration of cyclophosphamide (10 or 20 mg/kg bw) to the rats pre-treated with 80 mg/kg bw of nafenopin for 2 days resulted in significantly increased cytotoxic response in bone marrow cells. However, genotoxicity of cyclophosphamide was increased only in the liver of nafenopin pre-treated rats. Low level of genotoxicity in bone marrow could be accounted for potentiated cytotoxicity of cyclophosphamide. These events coincided with a significant, up to 5-fold, increase in indirect activation-detoxication index for cyclophosphamide, determined as a ratio of ECOD and GST activities, in nafenopin treated rats. This resulted from the induction of ECOD responsible for the formation of reactive metabolites of cyclophosphamide and reduced activity of GST responsible for their detoxication. In addition, mitotic activity of hepatocytes was increased in nafenopin treated rats that might also have an impact on the genotoxicity of cyclophosphamide in this organ.

Differential effect of peroxisome proliferators on rat glutathione S-transferase isoenzymes

We have investigated the effects of peroxisome proliferators silvex, nafenopin and diethylhexylphthalate (DEHP) on rat liver glutathione S-transferase (GST) isoenzyme activities and patterns. Silvex was a more potent in vitro GST inhibitor than nafenopin and DEHP. After 14 days oral administration to rats a reduction in total GST activity was observed, doses of compounds were chosen so that peroxisome proliferation was equivalent between compounds, nevertheless total GST activity was altered to different extents: nafenopin approximately silvex > DEHP approximately control. GST isoenzyme profiles were also altered, the proportion of GST 2-2 increased and 4-4 decreased compared to control levels. The results indicated that: (i) the peroxisome proliferators studied had similar effects on GST isoenzyme profile: (ii) modulation of the GST activity was apparently independent of peroxisome proliferation per se.

Effect of peroxisome proliferator nafenopin on the cytotoxicity of dihaloalkanes in isolated rat hepatocytes

Hepatocytes were isolated from nafenopin-treated animals (80 mg/kg body weight in 1.2 ml/kg body weight olive oil for 2 consecutive days) and exposed to various doses of 1,2 dichloroethane (DCE) (64-159 mumol) and 1,2-dibromoethane (DBE) (5.5-27.5 mumol) for up to 3 hr to assess the effect of nafenopin on the toxicity of dihaloalkanes. The activity of biotransformation enzymes involved in the activation and detoxication of these solvents was measured. Although cytochrome P450IIE1 activity was apparently unaltered, glutathione S-transferase activity was significantly reduced; the reduction was 20% for 1-chloro-2,4-dinitrobenzene as substrate but 40% and 80%, respectively for DBE and DCE. DBE was more than 10 times more cytotoxic to nafenopin-treated hepatocytes than DCE, and while very little change in DCE cytotoxicity was observed in hepatocytes isolated from nafenopin pretreated rats compared with control animals, DBE cytotoxicity was significantly potentiated in cells isolated from nafenopin-pretreated rats compared with cells from controls. It is believed that enhanced toxicity of DBE in isolated cells from nafenopin-treated rats is the result of modulation of dihaloalkane metabolism (glutathione conjugation).

Supporting children in need through a community-based orphan visiting programme

There is an urgent need for programmes to be established to support the growing number of orphans in countries severely affected by AIDS. Most orphans are being cared for by extended families under difficult circumstances. Few descriptions of community-based orphan support programmes exist. We describe one such programme established in Zimbabwe in 1993. Twenty-five volunteers identified 300 orphan households. During one year, volunteers made 1725 home visits and 123 households received an average of $11 in material support or school fees. In 292 orphan households there were 702 orphans, 14.7% of children under 15 years in the area. The rate of parental deaths was increasing with 3.5% of households in the area having a parental death in 1994. Forty-five per cent of caregivers were grandparents and 33% of caregivers were over 60 years. Three per cent of orphans were cared for by adolescent siblings. The poorest orphan households were those in receipt of school fees, with out-of-school children or with an older sibling as caregiver. Community members initiated activities to help orphans. The programme described is targeted, effective and replicable. Community-based organizations such as local churches and women's groups can be mobilized to administer programmes which provide support to the poorest orphan households.

Average speaking fundamental frequency in soprano singers with and without symptoms of vocal attrition

Nineteen trained soprano singers aged 18-30 years vocalized tasks designed to assess average speaking fundamental frequency (SFF) during spontaneous speaking and reading. Vocal range and perceptual characteristics while singing with low intensity and high frequency were also assessed, and subjects completed a survey of vocal habits/symptoms. Recorded signals were digitized prior to being analyzed for SFF using the Kay Computerized Speech Lab program. Subjects were assigned to a normal voice or impaired voice group based on ratings of perceptual tasks and survey results. Data analysis showed group differences in mean SFF, no differences in vocal range, higher mean SFF values for reading than speaking, and 58% ability to perceive speaking in low pitch. The role of speaking in too low pitch as causal for vocal symptoms and need for voice classification differentiation in vocal performance studies are discussed.

Crystal structure of AmiC: the controller of transcription antitermination in the amidase operon of Pseudomonas aeruginosa

The crystal structure for the negative regulator (AmiC) of the amidase operon from Pseudomonas aeruginosa has been solved at a resolution of 2.1 A. AmiC is the amide sensor protein in the amidase operon and regulates the activity of the transcription antitermination factor AmiR, which in turn regulates amidase expression. The AmiC structure consists of two domains with an alternating beta-alpha-beta topology. The two domains are separated by a central cleft and the amide binding site is positioned in this cleft at the interface of the domains. The overall fold for AmiC is extremely similar to that for the leucine-isoleucine-valine binding protein (LivJ) of Escherichia coli despite only 17% sequence identity, however, the two domains of AmiC are substantially closed compared with LivJ. The closed structure of AmiC is stabilized significantly by the bound acetamide, suggesting a molecular mechanism for the process of amide induction. The amide binding site is extremely specific for acetamide and would not allow a closed conformation in the presence of the anti-inducer molecule butyramide.

The effects of ibuprofen enantiomers on hepatocyte intermediary metabolism and mitochondrial respiration

In vivo and in vitro (-)R-ibuprofen is inverted to the (+)S antipode via stereoselective formation of an R-ibuprofenyl-CoA intermediate. In this study the effects of (-)R- and (+)S-ibuprofen on metabolism and respiration were studied using isolated rat hepatocytes and mitochondria. R-Ibuprofen significantly increased the lactate to pyruvate ratio, perturbed mitochondrial ketogenesis as evidenced by alterations in the beta-hydroxybutyrate to acetoacetate ratio and uncoupled mitochondrial oxidative phosphorylation. In addition, substantial dose- and time-dependent sequestration of reduced CoA (CoASH) occurred in the presence of the R enantiomer. Similarly, S-ibuprofen altered both the cytosolic and mitochondrial redox states although the magnitude of the effect was substantially less than that observed with the R enantiomer. In contrast to R-ibuprofen, S-ibuprofen did not uncouple oxidative phosphorylation or sequester hepatocyte CoASH. It is proposed that the perturbations observed in hepatocyte intermediary metabolism and mitochondrial function are attributable to a combination of the direct effects of R-ibuprofen per se and the sequestration of CoASH as R-ibuprofenyl-CoA during the process of chiral inversion. On the basis of these results, R-ibuprofen should be considered more in terms of metabolism to a reactive acyl-CoA intermediate rather than as a pro-drug for the pharmacologically active S-enantiomer.

Cloning and DNA sequence of amiC, a new gene regulating expression of the Pseudomonas aeruginosa aliphatic amidase, and purification of the amiC product

Using in vitro-constructed deletions and subcloned DNA fragments, we have identified a new gene, amiC, which regulates expression of the inducible Pseudomonas aeruginosa aliphatic amidase activity. The DNA sequence of the gene has been determined, and an open reading frame encoding a polypeptide of 385 amino acids (molecular mass, 42,834 Da) has been identified. A search of sequence libraries has failed to find homologies with other published sequences. The amiC translation termination codon (A)TGA overlaps the initiation codon for the downstream amiR transcription antitermination factor gene, implying that the amiCR operon is coordinately regulated. Disruption of the amiC open reading frame by insertion and deletion leads to constitutive amidase synthesis, suggesting that AmiC is a negative regulator. This is confirmed by the finding that a broad-host-range expression vector carrying amiC (pSW41) represses amidase expression in a series of previously characterized P. aeruginosa amidase-constitutive mutants. The AmiC polypeptide has been purified from PAC452(pSW41), and N-terminal amino acid sequencing has confirmed the gene identification.

Ocular injury induced by methyl ethyl ketone peroxide

Methyl ethyl ketone peroxide is a commonly used catalyst in various industries. We studied 19 eyes with a single exposure to methyl ethyl ketone peroxide that developed clinical patterns of mild injury, moderate injury, severe injury, or delayed keratitis. Delayed methyl ethyl ketone peroxide keratitis may cause exacerbations and remissions of corneal and limbal disease lasting more than 20 years with palpebral and bulbar hyperemia equal to the initial chemical exposure. With repeat exacerbation, further pannus may occur, which can be associated with a poorer outcome. Based on the capability of methyl ethyl ketone peroxide to change DNA to a new weak antigen, we suggest possible methods of therapy to prevent or limit delayed methyl ethyl ketone peroxide keratitis. This proposed type of injury has important implications in studying various limbal and corneal diseases. A major factor in the severity of ocular injury was the length of time from exposure to methyl ethyl ketone peroxide to obtaining a topical ocular local anesthetic to perform adequate lavage.

Positive control of Pseudomonas aeruginosa amidase synthesis is mediated by a transcription anti-termination mechanism

The DNA sequence of the region upstream from the amidase structural gene (amiE) of Pseudomonas aeruginosa indicates that amidase (EC 3.5.1.4) is transcribed from an Escherichia coli-like promoter located 150 bp before the amiE translation initiation codon. The sequence between the promoter and the coding sequence includes a single open reading frame followed by an E. coli-like rho-independent transcription terminator. A deletion within the presumed terminator region which disrupts the potential stem/loop formation leads to high constitutive amidase expression which is independent of the product of the regulator gene (amiR). It is proposed that the catabolic aliphatic amidase of P. aeruginosa is regulated by a transcription anti-termination mechanism. The magnoconstitutive mutant PAC433 has promoter and terminator sequences identical to the wild-type PAC1 but contains a single base pair change in the amiE gene ribosome-binding site.

An experiment in enzyme evolution. Studies with Pseudomonas aeruginosa amidase

The regulation of amidase synthesis in P. aeruginosa is under positive control. This review describes the experimental evolution of amidase and its regulator protein for the hydrolysis of novel substrates and experiments to elucidate the mechanism of the control system.

Studies on the expression of Cu,Zn superoxide dismutase in human tissues during development

The developmental expression of Cu,Zn superoxide dismutase in human lung and erythrocytes has been studied using activity measurements, immunoblotting and immunohistochemistry. Enzyme activity in erythrocytes increased significantly during gestation but no developmental trend was seen in lung. Immunoblotting identified a single enzyme form that was present in a variety of tissues and immunohistochemistry showed the enzyme to have widespread distribution in lung tissue. These data indicate that Cu,Zn superoxide dismutase is consistently expressed during human development and that, unlike in other species, no late-fetal surge in expression occurs.

A radioisotopic assay of picomolar concentrations of coenzyme A in liver tissue

A single-step enzyme assay using [14C]palmitic acid and bacterial acyl-coenzyme A synthetase (EC 6.2.1.3) is described for the determination of reduced coenzyme A (CoASH) levels in liver samples. Use of this technique provides a rapid and accurate determination of CoASH in the range 1-250 pmol. Application of the method to the quantitation of CoASH in samples of human liver tissue and rat liver homogenate, isolated hepatocytes, and mitochondria is described.

Studies on the developmental expression of glutathione S-transferase isoenzymes in human heart and diaphragm

The developmental expression of the basic, near-neutral and acidic isoenzymes of glutathione S-transferase (RX:glutathione R-transferase, EC 2.5.1.18) has been studied in heart and diaphragm. Neither these enzymes nor the putative muscle-specific GST4 isoenzyme demonstrated any developmental trends in expression. In vitro hybridisation and SDS-discontinuous polyacrylamide gel electrophoresis were used to show that the GST4 isoenzyme is a homodimer composed of monomers that have a slightly larger molecular weight than the near-neutral isoenzyme. The sensitivity of GST4 to inhibitors also appeared similar to that of the GST1 2 isoenzyme. Immunodiffusion and immunoblotting techniques were used to show that the acidic enzyme in muscle is immunologically identical to that in other tissues.

The amidase regulatory gene (amiR) of Pseudomonas aeruginosa

Recombinant plasmids carrying the amidase genes of Pseudomonas aeruginosa were used to study the genetic control of amidase synthesis in Escherichia coli and Pseudomonas aeruginosa. The amidase regulator gene, amiR, was found to lie about 2 kbp downstream from the structural gene, amiE. Using plasmids with in vitro-constructed deletions, and plasmids containing subcloned DNA fragments, the amiR gene was located within a 1 kbp ClaI-XhoI DNA fragment. The structural and regulator genes were shown to be transcribed in the same direction. Deletion of DNA sequences between the two genes resulted in increased synthesis of amidase in both E. coli and P. aeruginosa. The intervening sequences showed no repressing effect when tested in trans. The results suggested that the amiR gene could be transcribed from more than one promoter.

Haemoglobin A/F ratio in neonates at 7 days correlated with birth weight and estimated gestational age

Haemoglobin (Hb) A and Hb F has been determined in neonates of Afro-Caribbean and North European origin with gestational ages varying from 32 to 42 weeks. There was no difference in the distribution of Hb A/F ratios between the two groups. Only weak correlations could be established between the Hb A/F ratio and the estimated gestational age or birth weight. This would indicate that there is a considerable interindividual variation in the timing of the switching of haemoglobin synthesis from Hb F to Hb A and erythrocyte production from liver to bone marrow and of oxygen affinity of fetal blood. Thus, intra-uterine adjustments of the oxygen release capacity of haemoglobin would have to rest on biochemical mechanisms during the third trimester.

Interaction of benoxaprofen with rat erythrocytes: effects on oxidative metabolism and membrane ATPase activities

Incubation of rat erythrocytes with benoxaprofen resulted in increased glucose utilization, lactate production, depletion of cellular ATP and significant haemolysis. In isolated red cell membranes, benoxaprofen produced a dose related stimulation of both Ca2+ dependent and Ca2+ independent ATPase activities. Coincubation of either erythrocytes or red cell membranes with cysteine ameliorated the effects of benoxaprofen. A possible association exists between the mechanism of the reported anti-inflammatory activity of benoxaprofen and its cellular toxicity.