Cyclophosphamide and 4-Hydroxycyclophosphamide/aldophosphamide kinetics in patients receiving high-dose cyclophosphamide chemotherapy

Using a recently developed gas chromatography and mass spectrometry method to determine whole-blood cyclophosphamide (CP) and 4-hydroxycyclophosphamide/aldophosphamide (4-HO-CP/AP) concentrations, we investigated their pharmacokinetics in women receiving CP therapy. Patients (n = 18) received one or two courses of CP: (a) a 90-min i.v. infusion (4 g/m2) followed by a 96-h i.v. infusion (6 g/m2) in combination with high-dose thiotepa; or (b) a 96-h i.v. infusion (6 g/m2) in combination with high-dose thiotepa. Whole-blood exposures to CP [area under the whole blood concentration versus time curve (AUCCP)] and 4-HO-CP/AP (AUC4HOCP) between courses 1 and 2 were compared after normalization to dose (g/m2). A nonproportional increase was observed for the AUCCP between the first course [1112 micrometer. h/g/m2 +/- 14% coefficient of variation (CV)] and the second course (1579 micrometer . h/g/m2 +/- 28% CV) (P < 0.001). In contrast, the AUC4HOCP (27 micrometer . h/g/m2 +/- 25% CV) determined for the first course was 29% higher than the AUC4HOCP (21 micrometer . h/g/m2 +/- 26% CV) for the second course (P < 0.01). The interpatient whole-blood exposures to both CP and 4-HO-CP/AP were remarkably consistent in this patient population with percent CVs ranging from 14 to 28%. Because thiotepa (800 mg/m2) was administered simultaneously with CP during the second course of treatment, possible inhibition of CP metabolism by thiotepa was investigated using human liver microsomes in vitro. IC50 values determined for inhibition of CP metabolism in three individual liver donors ranged from 1.0 to 40 micrometer. However, the clinical relevance of this observation has not been established.     

Differential regulation of discrete apoptotic pathways by Ras

The products of the ras genes are known to regulate cell proliferation and differentiation; recently, they have been found to play a role in apoptosis. The expression of oncogenic p21(ras) in a number of cell types, including Jurkat (a human T lymphoblastoid cell line) and murine fibroblasts, makes the cells susceptible to apoptosis following suppression of protein kinase C (PKC) activity (PKC/Ras-mediated apoptosis). Engagement of Fas antigen, a potent effector of apoptosis, activates cellular p21(ras), which may be required for completion of the cell death program. To further investigate the role of p21(ras) in the regulation of apoptosis, the cellular mechanisms employed in these two apoptotic processes in which Ras activity is involved (PKC/Ras-related and Fas-triggered apoptosis), was explored. Increasing p21(ras) activity by expressing v-ras or by treatment with an antisense oligonucleotide to the GTPase-activating protein was found to accelerate the Fas-mediated apoptotic process in Jurkat and mouse LF cells. PKC/Ras-related apoptosis was associated with, and required, cell cycle progression, accompanied by the expression of the G1/S cyclins. In contrast, Fas engagement, although inducing a vigorous and PKC-independent activation of endogenous p21(ras), did not alter cell cycle progression, nor did it require such progression for apoptosis. Both the protein synthesis inhibitor cycloheximide and cyclin E antisense oligonucleotides partially abolished PKC/Ras-mediated apoptosis but had only a moderate effect on Fas-induced apoptosis. In contrast, the CED-3/interleukin-1beta-converting enzyme (ICE) protease inhibitor Z-VADfmk efficiently suppressed Fas-induced apoptosis and only marginally inhibited PKC/Ras-mediated apoptosis. Induction of both pathways resulted in activation of the Jun NH2-terminal kinase/JUN signaling system. These results suggest that different cell death programs, such as PKC/Ras-mediated and Fas-mediated apoptosis, may be interconnected via p21(ras) and perhaps Jun NH2-terminal kinase/JUN. In response to various death stimuli, p21(ras) may act as a common intermediate regulator in the transduction of apoptotic signals.     

Clinical interpretations of transient otoacoustic emissions

The object was to study retrospectively the perioperative complications and results of the Bologna procedure for the treatment of stress urinary incontinence associated with cystocele grade 2 or more. In the study, 80 patients underwent a repair of all defects of pelvic support plus the Bologna procedure. Mean duration of follow-up was 40.2 months (range 3-127). The incidence of operative complications was 2.5% for inadvertent cystostomy and for hemorrhage. Mean hospital stay was 7.2 days (range 2-17). At 2-year follow-up 85% of the patients were completely free of incontinence symptoms (95% CI: 75-92) and 76% at 3-year follow-up (95% CI: 66-86). None of the parameters tested in a univariate analysis was independently linked with surgical failure. Further studies are needed to establish the place of this technique in the surgical management of urinary incontinence associated with genital prolapse.     

Development and validation of a Structured Telephone Interview for Dementia Assessment (STIDA): the NIMH Genetics Initiative

Eating disorders are an increasing problem for society and the medical professions. The dental practitioner has an important role both in identifying the illnesses and in minimising its affects on the dentition. This paper highlights the features of the most common eating disorders and discusses the possible role of the dental profession in the long-term care of patients suffering from the problem.     

Seroprevalence of hepatitis B and C viral markers in patients with primary hepatocellular carcinoma in Singapore

This paper reviews studies on the basic principles of biostimulation of wound healing by various low-energy lasers. It looks at the mechanism of action of biostimulation as well as the laser's effect on cell proliferation, collagen synthesis, and would healing.     

Functionally distinct high and low molecular weight species of channel catfish and mouse IL-1

Culture supernatants from channel catfish monocytes exhibit IL-1-like activity for mouse and catfish T cells. Gel filtration analyses of these supernatants indicated that there were at least two forms of IL-1-like activity, i.e. a high molecular weight form (70 kD) active on channel catfish, but not mouse, T cells and a low molecular weight form (approximately 15 kD) with activity for mouse, but not catfish, T cells. Both sizes of catfish IL-1 exhibited alpha and beta determinants as shown by Western blot analyses using antisera to human IL-1 alpha and IL-1 beta. Further evidence for the IL-1 nature of these molecules was obtained by antibody inhibition assays wherein antisera to human IL-1 alpha and IL-1 beta each neutralized approximately 50% of the catfish activities, were additive to some extent, and could be reversed by the addition of the proper human recombinant protein. In culture supernatants of murine P388D1 cells functional activities for catfish and mouse T cells were found only in high and low molecular weight fractions, respectively. Western blots with antiserum to mouse IL-1 alpha revealed IL-1 determinants in both high and low molecular fractions of the mouse cell culture supernatants. These data suggest that catfish and mammalian IL-1 molecules may be quite similar with the caveat being that functional activity for catfish T cells requires a large protein, presented as an aggregate, a polymer, or simply a single chain 70 kD protein. However, only the low molecular weight forms (30 and 15 kD) are active on mouse T cells.     

A pH-dependent conformational change in the B-subunit pentamer of Escherichia coli heat-labile enterotoxin: structural basis and possible functional role for a conserved feature of the AB5 toxin family

The non-covalently associated B-subunit moieties of AB5 toxins, such as cholera toxin and related diarrheagenic enterotoxins, exhibit exceptional pH stability and remain pentameric at pH values as low as 2.0. Here, we investigate the structural basis of a pH-dependent conformational change which occurs within the B5 structure of Escherichia coli heat-labile enterotoxin (EtxB) at around pH 5.0. The use of far-UV CD and fluorescence spectroscopy showed that EtxB pentamers undergo a fully reversible pH-dependent conformational change with a pKa of 4.9 +/- 0.1 (R2 = 0.999) or 5.13 +/- 0.01 (R2 = 0.999), respectively. This renders the pentamer susceptible to SDS-mediated disassembly and decreases its thermal stability by 18 degrees C. A comparison of the pH-dependence of the structural change in EtxB5, with that of a mutant containing a Ser substitution at His 57, revealed that the pKa of the conformational change was shifted from ca. 5.1 to 4.4. This finding suggests that protonation of the imidazole side chain of His 57 might facilitate disruption of a spatially adjacent salt bridge, located between Glu 51 and Lys 91 in each B-subunit, thus triggering the conformational change in the pentameric structure. The pH-dependent conformational change was found to be inhibited when B-subunits bound to monosialoganglioside, GMI; and to have no effect on the stability of interaction between A- and B-subunits within the AB5 complex. This suggests that the conformational change is unlikely to have a direct involvement in toxicity. Conservation of the pH-dependent conformational change in the AB5 toxin family, combined with the potential exposure of the hydrophobic core of beta-barrel in the monomeric units, leads to the proposal that the conformational change may be the common feature that ensures the secretion of these proteins from the Vibrionaceae.     

Levels of organochlorine pesticides residues in milk of urban mothers in Kenya

Organochlorine compounds (OCPs) are toxic products capable of producing serious adverse health consequences. When used to control pests, certain OCPs persist in the environment and accumulate in the fatty tissues of living organisms, reaching higher levels in animals higher in the food chain. Many countries have therefore either restricted or banned the use of OCPs. DDT used to be widely used in Kenya to control pests, but is now used only to control mosquito populations. The contamination of human milk by organochlorine and other related compounds is a major concern in many parts of the world. Findings are reported from a study conducted to assess the levels of OCPs in an urban area of Kenya and to compare OCP levels in human milk from a previous study in rural areas of the country. 216 milk samples were collected from mothers aged 18-30 years in hospital maternity wards or attending postnatal clinics in selected areas in Nairobi in 1991. All mothers involved in the study were nursing either their first or second child, and had lived in Nairobi for at least 5 years before the date of sampling. Samples were collected from mothers who were up to 4 weeks postpartum and analyzed for the presence of OCP residues. 9 OCPs were detected, with p,p'DDT and p,p'DDE being the most frequently encountered contaminants in all samples analyzed. p,p'DDE was detected in 99.5% and p,p'DDT in 78.2% of all samples. Other residues detected were dieldrin (27%), beta-HCH (18.5%), lindane (12%), and alpha-HCH (8.8%). Levels of sum DDT ranged from 0.004 to 6.321 mg/kg fat. Mothers living in Nairobi have low levels of OCPs in their breast milk compared to mothers in rural areas. The relatively lower urban levels could be attributed to the restricted use of OCPs. People need to be taught how to safely use pesticides.     

Hypothermic modulation of cerebral ischemic injury during cardiopulmonary bypass in pigs

BACKGROUND: The aim of this study was to determine whether progressive levels of hypothermia (37, 34, 31, or 28 degrees C) during cardiopulmonary bypass (CPB) in pigs reduce the physiologic and metabolic consequences of global cerebral ischemia. METHODS: Sagittal sinus and cortical microdialysis catheters were inserted into anesthetized pigs. Animals were placed on CPB and randomly assigned to 37 degrees C (n = 10), 34 degrees C (n = 10), 31 degrees C (n = 11), or 28 degrees C (n = 10) management. Next 20 min of global cerebral ischemia was produced by temporarily ligating the innominate and left subclavian arteries, followed by reperfusion, rewarming, and termination of CPB. Cerebral oxygen metabolism (CMRO2) was calculated by cerebral blood flow (radioactive microspheres) and arteriovenous oxygen content gradient. Cortical excitatory amino acids (EAA) by microdialysis were measured using high-performance liquid chromatography. Electroencephalographic (EEG) signals were graded by observers blinded to the protocol. After CPB, cerebrospinal fluid was sampled to test for S-100 protein and the cerebral cortex was biopsied. RESULTS: Cerebral oxygen metabolism increased after rewarming from 28 degrees C, 31 degrees C, and 34 degrees C CPB but not in the 37 degrees animals; CMRO2 remained lower with 37 degrees C (1.8 +/- 0.2 ml x min[-1] x 100 g[-1]) than with 28 degrees C (3.1 +/- 0.1 ml x min[-1] x 100 g[-1]; P < 0.05). The EEG scores after CPB were depressed in all groups and remained significantly lower in the 37 degrees C animals. With 28 degrees C and 31 degrees C CPB, EAA concentrations did not change. In contrast, glutamate increased by sixfold during ischemia at 37 degrees C and remained significantly greater during reperfusion in the 34 degrees C and 37 degrees C groups. Cortical biopsy specimens showed no intergroup differences in energy metabolites except two to three times greater brain lactate in the 37 degrees C animals. S-100 protein in cerebrospinal fluid was greater in the 37 degrees C (6 +/- 0.9 microg/l) and 34 degrees C (3.5 +/- 0.5 microg/l) groups than the 31 degrees C (1.9 +/- 0.1 microg/l) and 28 degrees C (1.7 +/- 0.2 microg/l) animals. CONCLUSIONS: Hypothermia to 28 degrees C and 31 degrees C provides significant cerebral recovery from 20 min of global ischemia during CPB in terms of EAA release, EEG and cerebral metabolic recovery, and S-100 protein release without greater advantage from cooling to 28 degrees C compared with 31 degrees C. In contrast, ischemia during 34 degrees C and particularly 37 degrees C CPB showed greater EAA release and evidence of neurologic morbidity. Cooling to 31 degrees C was necessary to improve acute recovery during global cerebral ischemia on CPB.