A novel anti-HIV active integrase inhibitor with a favorable in vitro cytochrome P450 and uridine 5'-diphospho-glucuronosyltransferase metabolism profile

Research efforts on the human immunodeficiency virus (HIV) integrase have resulted in two approved drugs. However, co-infection of HIV with Mycobacterium tuberculosis and other microbial and viral agents has introduced added complications to this pandemic, requiring favorable drug-drug interaction profiles for antiviral therapeutics targeting HIV. Cytochrome P450 (CYP) and uridine 5'-diphospho-glucuronosyltransferase (UGT) are pivotal determining factors in the occurrence of adverse drug-drug interactions. For this reason, it is important that anti-HIV agents, such as integrase inhibitors, possess favorable profiles with respect to CYP and UGT. We have discovered a novel HIV integrase inhibitor (compound 1) that exhibits low nM antiviral activity against a diverse set of HIV-1 isolates, and against HIV-2 and the simian immunodeficiency virus (SIV). Compound 1 displays low in vitro cytotoxicity and its resistance and related drug susceptibility profiles are favorable. Data from in vitro studies revealed that compound 1 was not a substrate for UGT isoforms and that it was not an inhibitor or activator of key CYP isozymes.

Crystal structure and structural mechanism of a novel anti-human immunodeficiency virus and D-amino acid-containing chemokine

Chemokines and their receptors play important roles in normal physiological functions and the pathogeneses of a wide range of human diseases, including the entry of human immunodeficiency virus type 1 (HIV-1). However, the use of natural chemokines to probe receptor biology or to develop therapeutic drugs is limited by their lack of selectivity and the poor understanding of mechanisms in ligand-receptor recognition. We addressed these issues by combining chemical and structural biology in research into molecular recognition and inhibitor design. Specifically, the concepts of chemical biology were used to develop synthetically and modularly modified (SMM) chemokines that are unnatural and yet have properties improved over those of natural chemokines in terms of receptor selectivity, affinity, and the ability to explore receptor functions. This was followed by using structural biology to determine the structural basis for synthetically perturbed ligand-receptor selectivity. As a proof-of-principle for this combined chemical and structural-biology approach, we report a novel D-amino acid-containing SMM-chemokine designed based on the natural chemokine called viral macrophage inflammatory protein II (vMIP-II). The incorporation of unnatural D-amino acids enhanced the affinity of this molecule for CXCR4 but significantly diminished that for CCR5 or CCR2, thus yielding much more selective recognition of CXCR4 than wild-type vMIP-II. This D-amino acid-containing chemokine also showed more potent and specific inhibitory activity against HIV-1 entry via CXCR4 than natural chemokines. Furthermore, the high-resolution crystal structure of this D-amino acid-containing chemokine and a molecular-modeling study of its complex with CXCR4 provided the structure-based mechanism for the selective interaction between the ligand and chemokine receptors and the potent anti-HIV activity of D-amino acid-containing chemokines.

Is intralesional cidofovir worthwhile in juvenile recurrent respiratory papillomatosis?

OBJECTIVE

To investigate the efficacy of intralesional cidofovir in the treatment of recurrent respiratory papillomatosis (RRP) in children.

METHODS

Prospective observational study of four consecutive children with RRP treated at an academic tertiary children's hospital. Laryngo-bronchoscopy was performed at three- to five-weekly intervals. Photodocumentation was obtained and disease severity assessed using an anatomical RRP severity score. Surgical debulking of large papillomas was then performed, and cidofovir (5 mg/ml) injected into any remaining papillomas as well as submucosally at the sites of resected papillomas. The efficacy of cidofovir was assessed by the change in papilloma severity score over the course of the treatment.

RESULTS

Complete disease remission was obtained in one patient, with a partial response seen in two others. One patient showed no significant response. The greatest beneficial effect was seen after the fourth cidofovir injection; however, two patients demonstrated a deterioration in severity scores after treatment was withheld at this point. Both responded well to further cidofovir injections. However, a clear plateau in the response to cidofovir was seen in all patients by the eighth injection.

CONCLUSION

Intralesional cidofovir may help control papilloma regrowth and reduce disease severity in many children with RRP. In most cases, cidofovir would appear to be less efficacious in causing disease eradication. There appears to be little evidence to support prolonged treatment regimes (i.e. more than eight treatments).

Complications in paediatric airway management

Management of the paediatric airway can be difficult. This management in turn can be associated with complications which can be life threatening. We present three cases in which such complications occurred and then go on to discuss the different ways in which these can be prevented.

Type I laryngeal cleft: late presentation

Laryngeal cleft anomalies are rare congenital defects of the posterior laryngotracheal wall that usually present with a history of recurrent respiratory tract infections during the early neonatal period. Presentation of type I clefts can be subtle and subsequently can result in late diagnosis or indeed failure to present. We report on the case of a type I laryngeal cleft presenting with a history of recurrent lower respiratory tract infections and severe gastro-oesophageal reflux disease, at 19 years of age. This is the oldest documented initial presentation of a congenital laryngeal cleft, and emphasizes the importance of maintaining a suspicion of the diagnosis into early adulthood. We further highlight the role of gastro-oesophageal reflux disease in the presentation of laryngeal clefts.

Minor salivary glands: causing major problems

Tumours arising in the parapharyngeal space (PPS) are rare and account for approximately 0.5% of all head and neck neoplasms. These neoplastic processes represent a wide variety of both benign (80%) and malignant lesions arising from the diverse range of structures within and surrounding the PPS. The PPS is typically conceptualized as a potential neck space in the shape of an inverted cone with its base at the skull base and apex at the greater cornu of the hyoid. Because of this unique structure, lesions must often grow to a considerable size before symptoms become apparent and clinical detection is possible. A rare case of mucoepidermoid tumour of the minor salivary glands arising in the prestyloid parapharyngeal space is described. The complex anatomical and pathological considerations within this region present a substantial challenge to the head and neck surgeon in the evaluation and management of these lesions.

Iron chelation improves endothelial function in patients with coronary artery disease

BACKGROUND

Some epidemiological studies have shown that increased iron stores are associated with increased cardiovascular events. Redox-active iron may contribute to lipid peroxidation, endothelial cell activation, and generation of reactive oxygen species (especially hydroxyl radical, via Fenton chemistry). Increased oxidative stress is associated with impaired action of endothelium-derived nitric oxide in patients with atherosclerosis.

METHODS AND RESULTS

To test the hypothesis that reducing vascular iron stores would reverse endothelial dysfunction, we examined the effects of the iron chelator deferoxamine (500 mg intra-arterially over 1 hour) on vasomotor function in forearm resistance vessels of patients with coronary artery disease by venous occlusion plethysmography. Patients with coronary artery disease had impaired endothelium-dependent vasodilation in response to methacholine compared with healthy control subjects (P<0.001). Deferoxamine infusion decreased serum iron levels (P<0.001). Deferoxamine improved the blood flow response to methacholine in patients with coronary artery disease (P<0.01 by 2-way repeated-measures ANOVA) but had no effect on the response to sodium nitroprusside. In normal volunteers, deferoxamine had no effect on the response to methacholine. The nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine abolished augmentation of the methacholine response associated with deferoxamine. The hydroxyl radical scavenger mannitol had no effect on the methacholine response.

CONCLUSIONS

Deferoxamine improved nitric oxide-mediated, endothelium-dependent vasodilation in patients with coronary artery disease. These results suggest that iron availability contributes to impaired nitric oxide action in atherosclerosis.

Anti-HIV-1 activity of calanolides used in combination with other mechanistically diverse inhibitors of HIV-1 replication

The natural product (+)-calanolide A, a unique non-nucleoside reverse transcriptase inhibitor (NNRTI) of HIV-1 replication, is currently being evaluated in clinical trials in the USA. (+)-Calanolide A, the congeners costatolide and dihydrocostatolide, and (+)-12-oxo(+)-calanolide A, were evaluated in combination with a variety of mechanically diverse inhibitors of HIV replication to define the efficacy and cellular toxicity of potential clinical drug combinations. These assays should be useful in prioritizing the use of different combination drug strategies in a clinical setting. The calanolides exhibited synergistic antiviral interactions with other nucleoside and non-nucleoside reverse transcriptase inhibitors and protease inhibitors. Additive interactions were also observed when the calanolides were used with representative compounds from each of these classes of inhibitors. No evidence of either combination toxicity or antagonistic antiviral activity was detected with any of the tested compounds. The combination antiviral efficacy of three-drug combinations involving the calanolides, and the efficacy of two- and three-drug combinations using a (+)-calanolide A-resistant challenge virus (bearing the T139I amino acid change in the reverse transcriptase), was also evaluated in vitro. These assays suggest that the best combination of agents based on in vitro anti-HIV assay results would include the calanolides in combination with lamivudine and nelfinavir, since this was the only three-drug combination exhibiting a significant level of synergy. Combination assays with the (+)-calanolide A-resistant strain yielded identical results as seen with the wild-type virus, although the concentration of the calanolides had to be increased.

Unusual cause of subglottic stenosis in an adult

Subglottic foreign bodies presenting, as chronic subglottic stenosis is extremely rare in adults. A high index of suspicion and a careful history is of paramount importance in the diagnosis of a subglottic foreign body. Laser should not be used to excise granulation tissue to expose the foreign body because of the danger and potential of a fire particularly when the nature of the foreign body is not known. Rigid bronchoscopes are more beneficial than flexible ones in the removal of foreign bodies especially in long-standing cases.

Reduced hyaluronan in keloid tissue and cultured keloid fibroblasts

Extracellular matrix hyaluronan is prominent during wound healing, appearing at elevated levels early in the repair process. It is prevalent throughout the course of fetal wound healing, which is scar-free, but decreases late in adult wound repair, that is often marked by scarring. To determine whether aberrant hyaluronan metabolism is associated with the excessive scarring that characterizes keloids, cultured fibroblasts derived from keloids and from the dermis of normal human skin and scar were compared. Levels of hyaluronan in 48 h conditioned media of keloid-derived cultures were significantly lower than in cultures of normal skin and scar fibroblasts. Profiles of hyaluronan polymer size were comparable in these two cell types, suggesting that excessive hyaluronan degradation was not involved. Hydrocortisone decreased hyaluronan levels approximately 70% in the conditioned media of both keloid and normal fibroblasts. Diminished hyaluronan accumulation in keloid-derived cells compared with normal fibroblasts was also observed in an in vitro wound healing model. Histolocalization of hyaluronan in keloids, normal skin, and scar samples confirmed the biochemical observations that the dermis of keloids, which comprises most of the scar tissue, contained markedly diminished levels of hyaluronan. Alterations in hyaluronan in the epidermis overlying keloids, however, were also observed. A modest increase in hyaluronan staining intensity was observed in the epidermis of keloids, as well as changes in the patterns of distribution within the epidermis, compared with that in normal skin and scar. Increased hyaluronan was present in the granular and spinous layers of the keloid epidermis Abnormalities are present apparently in both the overlying epidermis as well as in the dermis of keloids. Aberrations in signaling between keloid stroma and keloid epidermis may underlie abnormalities that contribute to the excessive fibrosis characteristic of these lesions.

Anti-human immunodeficiency virus type 1 (HIV-1) activity of 2'-fluoro-2',3'-dideoxyarabinosyladenine (F-ddA) used in combination with other mechanistically diverse inhibitors of HIV-1 replication

2'-Fluoro-2'3'-dideoxyarabinosyladenine (F-ddA), a nucleoside reverse transcriptase inhibitor of human immunodeficiency virus (HIV) replication, is currently being evaluated in clinical trials. Future monotherapy for the treatment of HIV is unlikely owing to the rapid emergence of drug-resistant viruses, so F-ddA was evaluated in combination with a variety of mechanistically diverse inhibitors of HIV replication. Such in vitro studies provide insights into whether certain drug combinations yield synergistic antiviral activity or, more importantly, antagonistic antiviral activity or synergistic cytotoxicity. F-ddA exhibited synergistic antiviral interactions with representatives of each of the major classes of anti-HIV compounds, including other nucleoside reverse transcriptase inhibitors, non-nucleoside reverse transcriptase inhibitors and protease inhibitors. Greatest levels of synergistic interaction were detected when F-ddA was used in combination with the non-nucleoside compounds nevirapine and costatolide, the nucleoside analogues and costatolide, the nucleoside analogues AZT, ddC and 3TC and the protease inhibitors ritonavir and nelfinavir. No evidence of either combination toxicity or antagonistic antiviral activity was detected with any of the tested compounds.

Persistent otitis media with effusion: a new experimental model

OBJECTIVES/HYPOTHESIS

Numerous mechanical animal models for the creation of otitis media with effusion (OME) have been described since the 1920s. However, there are many problems associated with these models, including high infection rates, unreliability, and high resolution rates. The aim of the current study was to create a suitable mechanical animal model that would produce a sterile and long-lasting effusion.

STUDY DESIGN

A new technique using an external surgical approach on specific pathogen-free rats is described.

METHOD

The eustachian tubes of 56 rats were obstructed in the mid portion along the skull base with gutta percha.

RESULTS

All animals developed an effusion within 1 week of the procedure. The resolution rate was 8%, with 80% maintaining sterile effusions for up to 1 year.

CONCLUSIONS

This new procedure for an OME model has proved consistently reliable in creating a persistent and long-lasting effusion. It has a low infection rate and should benefit future studies on the prolonged effects of OME on the tympanic membrane and middle ear.

Intensive nutritional counselling in bulimia nervosa: a role for supplementation with fluoxetine?

OBJECTIVE

The aims of the paper are to determine whether nutritional counselling is associated with an improvement in bulimic symptomatology, whether this improvement is maintained during post-treatment follow-up, and whether the addition of fluoxetine 3 x 20 mg/day confers additional benefit.

METHOD

Psychological, pharmacological and combined psychopharmacological treatments of bulimia nervosa were reviewed briefly. Sixty-seven patients referred to specialist eating disorder services who fulfilled strict diagnostic criteria were treated with intensive nutritional counselling and randomly assigned to either fluoxetine 3 x 20 mg/day or placebo. After a 1-week 'wash-out', active treatment was given over 8 weeks, followed by post-treatment interviews at 12 and 20 weeks.

RESULTS

Both groups of patients improved significantly during treatment. In some respects, the fluoxetine group did slightly better as demonstrated by the items 'restraint', 'weight concern' and 'shape concern' (p < 0.05 vs p < 0.0001) on the Eating Disorder Examination (EDE). Fluoxetine patients decreased their energy intake and lost a modest amount of weight. They went on to regain weight during the follow-up period, returning to levels higher than they were initially. These patients also appeared more likely to have a recurrence of symptoms, as shown by the fall in percentage of binge-free patients and by changes in the EDE.

CONCLUSION

Nutritional counselling is an effective means of treating bulimia nervosa, with improvement maintained up to 3 months follow-up. The addition of fluoxetine may confer some benefit during active treatment, but its discontinuation may contribute to a higher rate of recurrence of symptoms post treatment. Of course, this study cannot be extrapolated to the efficacy of fluoxetine when used as the only form of treatment in patients for whom intensive nutritional counselling or other structured psychological programs are not available.

Highly potent oxathiin carboxanilide derivatives with efficacy against nonnucleoside reverse transcriptase inhibitor-resistant human immunodeficiency virus isolates

The structure-activity relationships of a series of compounds related to the nonnucleoside reverse transcriptase (RT) inhibitor (NNRTI) oxathiin carboxanilide have been described (R. W. Buckheit, Jr., T. L. Kinjerski, V. Fliakas-Boltz, J. D. Russell, T. L. Stup, L. A. Pallansch, W. G. Brouwer, D. C. Dao, W. A. Harrison, R. J. Schultz, J. P. Bader, and S. S. Yang, Antimicrob. Agents Chemother. 39:2718-2727, 1996). From these studies, the furanyl-containing analog UC10 was identified as the most potent inhibitor of human immunodeficiency virus type 1 (HIV-1) replication and a promising candidate for further development. Three new UC analogs (UC040, UC82, and UC781) have been determined to inhibit laboratory-derived and low-passage-number, primary virus isolates at low nanomolar concentrations in both established and fresh human cells. Each of the compounds synergistically interacted with the nucleoside analogs zidovudine, dideoxyinosine, dideoxycytosine, and lamivudine to inhibit HIV-1 replication. As a group, the UC compounds were found to be less active against viruses with the L100I, K103N, and Y181C amino acid changes in the RT and, upon in vitro selection, yielded resistant virus with the Y181C mutation in the RT. The most potent of the three new compounds, UC781, contains a furanyl side chain, similar to UC10, but differs in having an extended ether side chain instead of an oxime chain. The broad therapeutic index of UC781 (>62,000) resulted in effective inhibition of NNRTI-resistant virus isolates at high nanomolar concentrations. Furthermore, UC781 and the NNRTI costatolide were able to synergistically inhibit HIV-1 replication when used in combination, suggesting that UC781 may interact with the RT differently than the other UC analogs. The favorable anti-HIV properties of the UC compounds suggest they should be considered for further clinical development.

Isolation of viruses from clinical specimens in microtitre plates with cells inoculated in suspension

Virus isolation is essential for the provision of a full diagnostic virology service. Present methods are time consuming, expensive and relatively inflexible for routine use. Our objective was to audit our existing virus isolation system and to develop a sensitive, flexible virus isolation system which could be adapted for use in a busy routine laboratory which is required to provide a service for a wide range of clinical situations. We carried out a pilot study which compared conventional roller tube monolayer cultures to a microplate system using cells inoculated in suspension and showed that the microplate method using extra cell lines could provide a more sensitive system for virus isolation. This system was adapted for routine use using six cell lines inoculated in suspension and the results are presented for 2610 specimens for virus isolation and 972 for Clostridium difficile toxin (CDT) detection. There were 516 viruses isolated and 229 specimens positive for CDT using this system. Polioviruses (92), echoviruses (35), coxsackieviruses (15) and untyped enteroviruses (13) were isolated in RMK, E6-vero and RD cells. Adenoviruses (137) were isolated in HEp2 and E6-vero cells. Herpes simplex virus (HSV) was isolated from 149 specimens in E6-vero, FCL and HFF9 cells. Myxoviruses (38) and paramyxoviruses were isolated in RMK cells. HEp2 was the only cell line necessary to isolate the 33 respiratory syncytial viruses (RSV). Cytomegaloviruses (CMV) (2) and varicella zoster (1) virus (VZV) were isolated only in the human fibroblast cell line HFF9. Rubella virus was isolated from a baby with congenital rubella in RMK, E6-vero and additionally in BGM cells. In conclusion, the use of cells inoculated in suspension in microtitre plates for virus isolation was sensitive and convenient. It allowed the use of six cell lines for routine virus isolation without using additional laboratory staff time. It improved turnaround times. It was also safer microbiologically than conventional isolation in tube monolayers. The precise identification of virus isolates was simplified.

Biological and biochemical anti-human immunodeficiency virus activity of UC 38, a new non-nucleoside reverse transcriptase inhibitor

UC 38, a simple analog of oxathiin carboxanilide, UC 84, lacking the oxathiin ring, was found to be a potent inhibitor of human immunodeficiency virus (HIV)-1-induced cell killing and HIV replication in a variety of human cell lines, as well as in human peripheral blood lymphocytes and macrophages. UC 38 was active against a wide range of biologically diverse laboratory and clinical strains of HIV-1. However, UC 38 was inactive against HIV-2 and both nevirapine- and pyridinone-resistant strains of HIV-1. UC 38 selectively inhibited HIV-1 reverse transcriptase (RT), but not HIV-2 RT. Combination of UC 38 with 3'-azido-3'-deoxythymidine synergistically inhibited HIV-induced cell killing. An HIV-1 isolate resistant to UC 38 was selected in cell culture, and the mutations in the RT nucleotide sequences were determined. Comparison with the wild-type RT sequence revealed an amino acid change at position 181 (Tyr to Cys). The UC 38-resistant virus was found to be cross-resistant to a variety of structurally diverse non-nucleoside RT inhibitors. UC 38 was susceptible to rapid degradation in vitro and in vivo; yet, nontoxic in vivo concentrations of UC 38 many-fold in excess of the in vitro effective concentrations could be achieved and maintained after s.c. or p.o. administration in hamsters. These results establish UC 38 as a new chemotype within the general class of HIV-1-specific RT inhibitors. The favorable physical characteristics, lack of toxicity, potency and bioavailability of UC 38 may make it a candidate for combination chemotherapy of acquired immune deficiency syndrome.

Structure-activity and cross-resistance evaluations of a series of human immunodeficiency virus type-1-specific compounds related to oxathiin carboxanilide

A series of compounds related to the nonnucleoside reverse transcriptase (RT) inhibitor (NNRTI) oxathiin carboxanilide (UC84) were evaluated for activity against the human immunodeficiency virus (HIV) to determine structural requirements for anti-HIV activity. Twenty-seven compounds representative of the more than 400 Uniroyal Chemical Company (UC) compounds were evaluated for structure-activity relationships. Several of the compounds evaluated were highly active, with 50% effective concentrations in the nanomolar range and therapeutic indices of > 1,000. Highly synergistic anti-HIV activity was observed for each compound when used in combination with 3'-azido-3'-deoxythymidine; additive to slightly synergistic interactions were observed with the compounds used in combination with dideoxycytidine. In combination with the NNRTI costatolide, only UC38 synergistically inhibited HIV type 1. Residues in the RT which, when mutated, impart resistance to the virus isolates selected in cell culture, against virus variants with site-directed mutations, and against RTs containing defined single amino acid changes. The mutations included changes in RT amino acids 100, 101, 103, 106, 108, and 181. The results with isolates selected in cell culture indicate that the carboxanilide compounds interact with the RT at two vulnerable sites, selecting UC-resistant virus isolates with the Y-to-C mutation at position 181 (Y181C) or the L100I substitution. A resistant virus isolate containing both Y181C combination with calanolide A, an NNRTI which retains activity against virus with the single Y181C mutation, UC10 rapidly selected a virus isolate with the K103N mutation. The merits of selecting potential candidate anti-HIV agents to be used in rational combination drugs design as part of an armamentarium of highly active anti-HIV compounds are discussed.

Body composition in anorexia nervosa - changes with treatment, determinants and techniques

Body fat, total body water and totally body nitrogen were estimated twice before and after refeeding in 32 patients with anorexia nervosa. Body composition was estimated once in 29 normal controls using the techniques of anthropometry, impedance and IVNCA. The influence of weight gain and other variables, ie psychological status, biochemical parameters, exercise and dietary composition, on protein repletion was examined. Methods of assessment of body composition were compared. The results demonstrated that in anorexia nervosa patients, protein was more completely replenished than fat when patients had reached 85% of average body weight for height and age. Weight gain was the only determinant of protein gain. There was no correlation with psychological, biochemical or exercise status nor with dietary composition. Direct methods, ie deuterium dilution and IVNCA, were shown to be preferable in determination of body composition in anorexia nervosa.

Glucocorticoid regulation of elastin synthesis in human fibroblasts: down-regulation in fibroblasts from normal dermis but not from keloids

Keloids arise as benign connective tissue masses at sites of injury in genetically predisposed individuals. In addition to excessive collagen accumulation, there is biochemical and histologic evidence of elastic tissue. Previous studies showed that glucocorticoid regulation of collagen synthesis differs in fibroblasts from normal adult dermis and keloids. To define further the abnormal regulation of matrix synthesis in keloid fibroblasts, we examined glucocorticoid regulation of elastin synthesis. The basal level of elastin synthesis was significantly higher in keloid than in normal cells, and hydrocortisone reduced synthesis of elastin and elastin mRNA in normal but not in keloid fibroblasts. We had shown previously that fibroblasts from fetal dermis resembled keloid fibroblasts in glucocorticoid regulation of growth and collagen synthesis. In this study, glucocorticoids failed to down-regulate elastin synthesis in fetal cells that had not differentiated to produce normal levels of elastin, whereas fetal cells with normal elastin production exhibited glucocorticoid down-regulation. Abnormal regulation in keloid cells was independent of cell density and was confined to fibroblasts cultured from the keloid nodule. These findings reinforce the conclusion that a matrix-regulatory pathway is deranged in these focal lesions. Coordinate down-regulation of collagen and elastin by hydrocortisone in normal adult dermal fibroblasts and the failure of hydrocortisone to down-regulate synthesis of either protein in keloid cells support the existence of common elements in the regulatory pathways of these two matrix proteins.

Cordectomy: a solution to Teflon granuloma of the vocal fold

Teflon injection has been widely used for the treatment of unilateral vocal fold paralysis. Complications are few and infrequent. Overinjection and Teflon granuloma are the two commonest problems encountered. Treating such complications and restoring vocal quality is widely regarded as difficult. Endoscopic transmucosal excision of the excess Teflon and/or granuloma has not been successful in improving phonatory quality. Cordectomy is proposed as an alternative surgical approach for managing both the convex vocal fold and Teflon granuloma after injection.

Development of a central matching system for the allocation of cadaveric kidneys: a simulation of clinical effectiveness versus equity

OBJECTIVES

1) To develop a computer-based simulation to prospectively study the impacts of explicitly incorporating different equity criteria into the process of allocating kidneys to recipients, given the scarcity of this resource. 2) To assess the tradeoffs between systems that allocate kidneys based only on medical criteria, systems that allocate kidneys based only on equity criteria, and systems that consider both medical and equity criteria.

METHODS

A computer-based simulation was developed that describes the flows of patients and kidneys. This model provides information at various time points about the number of patients in the system who are awaiting transplants, the number of kidneys available for transplantation, the number of transplantations performed for each matching algorithm, and the number of kidneys discarded (when applicable), as well as the means and standard deviations of the HLA-match scores, number of days from registration to transplantation, and number of days (from registration) of those who are still waiting for transplants. Five different matching algorithms were compared, ranging from determination of the allocation by a single medical criterion (i.e, HLA match) to determination by a single equity criterion (i.e., relative position in the waiting queue). The remaining algorithms represent different strategies of weighting these two considerations. Estimates regarding the main parameters of the model were derived utilizing data collected through the Multiple Organ Retrieval and Exchange Programme of Ontario, Canada.

RESULTS

The simulation was set to run for a period of ten years. A tradeoff between graft survival (or improved HLA matching) and equal treatment of patients regardless of their likelihood to benefit was found. It is clear that an algorithm that allocates kidneys based only on temporal location of patient on the waiting list is likely to be unacceptable because of the very poor average HLA-match scores that it yields. Pool size was found to be a major determinant in the attainment of optimal matching from a medical perspective.

CONCLUSIONS

1) The final choice about any allocation algorithm to be used requires that a value judgment be made, i.e., how great a reduction in HLA-match score should be traded in order to improve equity score (or vice versa). 2) A computer-based simulation model is a feasible way to prospectively test the impact of any given allocation algorithm on any given system.

Excessive physical activity in dieting disorder patients: proposals for a supervised exercise program

A relationship between starvation and hyperactivity has been observed in animal models, in experiments with human subjects, and in dieting disorder patients. Since the earliest descriptions of anorexia nervosa, excessive physical activity has figured prominently as a symptom of the illness, yet little attention has been directed towards this phenomenon. The aims of this paper are to review the published literature, to report our experience of the role of physical overactivity in the clinical presentation of dieting disorders, to discuss its implications for treatment, and to propose a supervised exercise program by which overactivity may be addressed specifically in the treatment of these patients.

Protein repletion and treatment in anorexia nervosa

Body fat and total body nitrogen (TBN) were quantified before and after refeeding in 32 female anorexia nervosa patients and in 29 matched control subjects by using the techniques of anthropometry and in vivo neutron-capture analysis (IVNCA). Mean body weight of patients (mean body mass index; BMI, in kg/m2), 15.4 +/- 1.3, was 72.7% of that of control subjects, increasing to 89.8% of mean weight of control subjects after refeeding (mean BMI 19.0 +/- 1.2). Mean BMI of control subjects was 21.6 +/- 2.7. Compared with the control group, patients' nitrogen was initially depleted by 24.5%, increased by 18.4%, but remained 10.6% below control values (P < 0.001). Body fat was depleted by 58.4%, increased by 89.7%, but remained 21.8% below control values (P < 0.001). Thus, despite a greater initial depletion and subsequently a greater net gain, body fat remained relatively more depleted after treatment than did nitrogen and protein. Anorexia nervosa patients were shown to readily replenish protein during nutritional rehabilitation.

What causes acute otitis externa?

External otitis is an extremely common condition and can affect between five to twenty per cent of the patients attending ENT clinics (Hawke et al., 1984). Its precise pathogenesis remains unclear, despite several aetiological classifications in the literature. The aim of this study was to investigate the relationship between infection, water exposure and trauma and the development of acute otitis externa. The study comprised 100 patients with their first attack of otitis externa and 150 age and sex matched controls. In only 40 per cent of cases could a primary microbiological cause be found. There was no significant statistical difference found between the two groups regarding the use of agents capable of traumatizing the external canal. Regular swimming, showering and hair washing were significantly more common in patients with acute otitis externa. Allergic disorders were nearly three times more common in the external otitis group suggesting a possible immunological aetiology.

Innervation of the rat tympanic membrane from the superior cervical and glossopharyngeal ganglia

True Blue and Fluorogold were applied to the external surface of the tympanic membrane and middle ear mucosa of Sprague-Dawley rats and neurons in the superior cervical and glossopharyngeal ganglia were labelled with these retrograde tracer dyes. Dye absorption was poor from the tympanic membrane unless the keratinized layer was damaged with crystalline silver nitrate prior to dye application. Stained neurons were scattered throughout the superior cervical ganglion with no evidence of somatotopy. Several neurons in the glossopharyngeal ganglion stained with both dyes when these had been simultaneously applied to both sites in single animals. There was no evidence of dual staining of neurons in the superior cervical ganglion.

Brachytherapy for recurrent nasopharyngeal and naso-ethmoidal tumours

Recurrent or persistent carcinoma of the nasopharynx or naso-ethmoid region occurs even after combined surgery and radical external irradiation. The confined bony access and proximity of vital structures may compromise resection margins. Brachytherapy using implantable radioactive gold or iodine seeds is a useful adjunct to the skull base surgeon in eliminating residual microscopic disease. We report nine cases with recurrent or persistent disease of the nasopharynx or naso-ethmoid regions treated with brachytherapy with encouraging results.

The quality of life in renal transplantation--a prospective study

Methodologically sound measures of quality of life are required to judge accurately the impact of successful renal transplantation on patient well-being. The time trade-off (TTO) method is a reproducible and valid measure which we used to prospectively assess changes in the quality of life of 27 patients on maintenance dialysis who subsequently underwent renal transplantation. TTO scores approaching 0 signify a very poor quality of life, while scores approaching 1 represent perfect health. Of 98 dialysis patients who completed baseline TTO interviews, 31 consecutive patients subsequently received 28 cadaveric and 3 living related kidney transplants. Four of 31 patients did not complete a second TTO assessment, because of death in 2 patients and graft loss in 2 others. The remaining 27 patients completed a second TTO interview an average of 30.9 months following transplantation (range 1.5-52, 95% confidence interval [CI] 24.4-37.5) and formed the study cohort. At the time of study the mean serum creatinine for the cohort was 173 mumol/L (range 90-290, 95% CI 152-195 mumol/L). The employment rate rose 27% following transplantation (P = 0.10); but when males alone were analyzed, a significant increase of 38% (P = 0.048) was noted. During the dialysis period, the mean baseline TTO score was 0.41 (95% CI 0.33-0.49), confirming the observations of others. Following transplantation, the mean TTO score rose to 0.74 (95% CI 0.67-0.81), a difference that is statistically significant (P < 0.001). The mean increase in TTO score observed as a result of successful transplantation was 0.33 (95% CI 0.26-0.40). This magnitude of improvement was found in 20 of 27 patients (74%), whose TTO scores lay within or above the 95% CI (0.26-0.40) for the mean change in score of 0.33. One patient's score fell, while the remaining 6 patients had improvements in their TTO score which fell below the lower 95% CI value (0.26) for the mean change in score. We conclude that the 95% CI of 0.26-0.40 identifies a range in which clinically important improvements in quality of life will be found for the majority of patients receiving successful kidney transplants.

The Parental Bonding Instrument in adolescent patients with anorexia nervosa

The Parental Bonding Instrument (PBI) was administered to 54 adolescent patients with anorexia nervosa. Scores were compared with those of matched groups of normal and of nonanorectic adolescents referred for assessment to an adolescent psychiatric unit. Significant differences between the 3 groups were demonstrated with respect to care and protection dimensions. Overall scores of subjects in the anorectic group resembled those of normals rather than those of referred patients. Anorexia nervosa patients described their fathers and mothers as being more caring and their mothers as being less overprotective than did psychiatrically referred peers. The study raised questions concerning the use of the PBI in adolescents, in particular those with anorexia nervosa, and the role of the family in the aetiogenesis of this condition.

Necrotizing sialometaplasia

Necrotizing sialometaplasia is a benign self-limiting disorder which can simulate malignancy. We report the third such case of nasal fossa involvement in the literature. The pathology of this condition is discussed.

Keloid fibroblasts are refractory to inhibition of DNA synthesis by phorbol esters. Altered response is accompanied by reduced sensitivity to prostaglandin E2 and altered down-regulation of phorbol ester binding sites

To investigate abnormal growth regulation in keloid fibroblasts, responses to phorbol esters were examined. Treatment of quiescent cultures with phorbol 12-myristate 13-acetate (PMA) blocked a normally occurring (20-24 h) peak of serum-stimulated thymidine incorporation in normal and keloid cells. In keloid fibroblasts PMA induced a delayed peak of DNA synthesis. When indomethacin was added with PMA the delayed peak appeared in normal fibroblasts. The ED50 for inhibition of the 20-24-h peak was 1 nM, whereas the delayed peak required a 50-fold-higher PMA concentration. In both cell types PMA induced prostaglandin E2 (PGE2) synthesis, and exogenous PGE2 caused 50% inhibition of the 20-24-h peak. When PMA and indomethacin were added with PGE2 the delayed peak was inhibited 90% in normal fibroblasts, whereas inhibition of keloid cells was the same as with PGE2 alone. Normal and keloid fibroblasts had the same number of phorbol ester binding sites. However, in normal cells, phorbol 12,13-dibutyrate bound with greater affinity, and down-regulation of phorbol ester binding occurred to a greater extent. These findings suggest that altered expression of protein kinase C isozymes or another molecule that binds phorbol esters may play a role in abnormal growth regulation of keloid cells.

Electron beam versus photon beam radiation therapy for the treatment of orbital lymphoid tumors

Shielding the lens of the eye while treating orbital lymphoid tumors and achieving a relatively homogeneous dose can be a dosimetric challenge. There are many clinical cases of tumors close to one or both eyes, where it is desirable to spare the lens as much as possible. We will show isodose curves comparing direct anterior fields using various electron beam energies to a single 6 mv photon beam to a multifield combination. The presence of an eye shield in a photon beam may impair the dose distribution at the back of the eye to an undesirable degree. The strong in-depth dose drop-off in electrons and the ease with which the beam can be intercepted suggests that an electron beam with an eye shield may offer advantages. We designed a suspended movable lens shield .8 cm wide with a height of 4.5 cm made of cerrobend surrounded by a brass cylinder mounted to a thin plexiglass plate to insert into a Varian electron 6 x 6 cone. A 1.5 cm gap between block and eye surface was used. Verification of dose distribution under the lens shield was obtained by film dosimetry.

Can overuse of psychotropic drugs by the elderly be prevented?

Despite increasing awareness of the problems associated with long term psychotropic use, consumption by the elderly remains high. This study examines some of the reasons for this with a view to prevention. Fifty seven elderly patients using psychotropic medication were interviewed to determine the prevalence of psychiatric illness, patterns of drug use, the reasons for the initial prescription and any relationship to life events. Attitudes to continued use were also assessed. The results suggest that levels of psychotropic use by the elderly could be reduced by improved management of life crises and insomnia.

Psychiatry and the frontal lobes

The frontal lobes of the brain have long been regarded as enigmatic in their function and perhaps should be considered even more so in states of dysfunction. Observed associations between structural lesions and psychiatric symptoms and the demonstration of disturbed function and morphology in the frontal lobes of individuals suffering from major psychiatric disorders have led to increased interest in this brain area. Psychiatrists have been particularly concerned with seeking the aetiogenesis of common diagnostic entities and this article attempts to synthesize the available facts. A brief overview of relevant biological data precedes a description of methods of neuropsychological testing and the clinical features arising from frontal lobe damage. A discussion of the role of the frontal lobes in some aspects of personality function follows. Neuropsychiatric features associated with known frontal lobe pathology are described, prefacing a discussion of those psychiatric conditions where an aetiological role for frontal lobe dysfunction has been proposed.

Calcium antagonists and acute renal failure

PURPOSE

To critically review the question of whether calcium antagonists can prevent or attenuate post-ischemic acute renal failure (ARF).

PATIENTS AND METHODS

Using a computer-assisted search, we identified all experimental and clinical studies published in English between 1980 and 1988 in which the main research question addressed the efficacy of verapamil, diltiazem, or nifedipine in the treatment of post-ischemic ARF. Studies were then selected for review based on clearly specified inclusion criteria and evaluated against accepted methodologic guidelines.

RESULTS

In experimental studies of warm renal ischemia, calcium antagonists provided significant protection of glomerular filtration rate (GFR) when given before and after ischemic injury; however, isolated pre- or post-ischemic treatment produced equivocal results. In autotransplantation studies on protracted cold ischemia, verapamil produced a modest, although physiologically significant, increase in GFR during warm reperfusion but failed to alter graft survival. Studies of calcium antagonists in humans with ARF have been confined to patients undergoing renal transplantation. Diltiazem given both to donor grafts and to recipients produced a significant reduction in the rate of delayed graft function but failed to improve one-year graft survival. This result may be due to the study of small numbers of low-risk patients. At present, there is no conclusive evidence that one calcium antagonist is more efficacious than another in the treatment of post-ischemic ARF.

CONCLUSIONS

Calcium antagonists appear to prevent or reduce the severity of post-ischemic ARF only when given prior to and after the ischemic insult. As a result, these agents will have most utility in the setting of renal transplantation. Although the efficacy of these agents in reducing delayed graft function appears to be established, their failure to improve graft survival is poorly understood and requires further investigation.

Differential glucocorticoid regulation of collagen mRNAs in human dermal fibroblasts. Keloid-derived and fetal fibroblasts are refractory to down-regulation

Abnormal regulation of collagen synthesis has been observed in fibroblasts from keloids, benign collagenous tumors that develop as a result of an inherited defect in dermal wound healing. Hydrocortisone reduces the rate of collagen synthesis in fibroblasts from normal adult dermis and scars, but fails to down regulate collagen synthesis in keloid-derived fibroblasts. We show here that loss of glucocorticoid control of collagen synthesis in keloid cells is due to an inability of hydrocortisone to reduce the levels of types I, III, and V collagen mRNA, whereas it coordinately lowers these RNAs in normal adult cells. The defective regulatory mechanism is expressed only in fibroblasts from the lesion. Fibroblasts from uninvolved dermis respond normally to hydrocortisone. Not all glucocorticoid-modulated matrix proteins are abnormally regulated in this disorder; fibronectin mRNA is induced to a similar extent in normal and keloid cells. The failure of hydrocortisone to reduce collagen gene expression is also seen in fibroblasts from fetal dermis. We have reported similarities between keloid and fetal cells with regard to growth factor requirements and growth response to hydrocortisone. Thus, keloids may be due to the inappropriate expression of a pattern of growth and matrix production that is developmentally regulated.

Benzodiazepine use in a rural general practice population

This study investigates the prevalence and pattern of benzodiazepine use in an isolated Australian rural general practice setting. Some clinical features of psychological dependence were also examined. Data were obtained from 771 patients attending each of two general practices over a five-day period. The results indicated that 11.3% of the sample had used a benzodiazepine in the preceding four weeks and that 82% of these had been regular users for over six months. Prevalence increased with age and 36.5% of patients over the age of 70 were using benzodiazepines. Features suggesting some degree of psychological dependence were found in over 50% of users. The findings illustrate the extensive and prolonged use of benzodiazepines and raise questions about overuse and dependence, particularly in the elderly.

Anorexia tardive: a diagnosis of exclusion?

An elderly female patient is described in whom rapid severe weight loss appeared initially to be of psychogenic origin and self-induced. A diagnosis of late-onset anorexia nervosa or anorexia tardive was made when early investigations revealed no abnormality apart from changes that were consistent with malnutrition, and when typical behavioural and psychological factors together with putative psychodynamic issues were revealed. At first, nasogastric feeding was beneficial, but a stormy hospital course ensued. Further investigations revealed the presence of neoplastic disease which at post-mortem examination proved to be small-cell carcinoma of the lung.

Reduced growth-factor requirement of keloid-derived fibroblasts may account for tumor growth

Keloids are benign dermal tumors that form during an abnormal wound-healing process in genetically susceptible individuals. Although growth of normal and keloid cells did not differ in medium containing 10% (vol/vol) fetal bovine serum, keloid cultures grew to significantly higher densities than normal cells in medium containing 5% (vol/vol) plasma or 1% fetal bovine serum. Conditioned medium from keloid cultures did not stimulate growth of normal cells in plasma nor did it contain detectable platelet-derived growth factor or epidermal growth factor. Keloid fibroblasts responded differently than normal adult fibroblasts to transforming growth factor beta. Whereas transforming growth factor beta reduced growth stimulation by epidermal growth factor in cells from normal adult skin or scars, it enhanced the activity of epidermal growth factor in cells from keloids. Normal and keloid fibroblasts also responded differently to hydrocortisone: growth was stimulated in normal adult cells and unaffected or inhibited in keloid cells. Fetal fibroblasts resembled keloid cells in their ability to grow in plasma and in their response to hydrocortisone. The ability of keloid fibroblasts to grow to higher cell densities in low-serum medium than cells from normal adult skin or from normal early or mature scars suggests that a reduced dependence on serum growth factors may account for their prolonged growth in vivo. Similarities between keloid and fetal cells suggest that keloids may result from the untimely expression of a growth-control mechanism that is developmentally regulated.