Detection of Rater Errors on Cognitive Instruments in a Clinical Trial Setting

OBJECTIVES

This study examines errors committed by raters in a clinical trial of a memory enhancement compound.

BACKGROUND

Findings of clinical trials are directly dependent on the quality of the data obtained but there is little literature on rates or nature of rater errors on cognitive instruments in a multi-site setting.

DESIGN

Double-blind placebo-controlled study.

SETTING

21 clinical sites in North America.

PARTICIPANTS

Two hundred seventy-five participants.

MEASUREMENTS

MMSE, WMS-R Logical Memory I and II, WMS-R Verbal Paired Associates I, WASi Vocabulary, WASi Matrix Reasoning, GDS and MAC-Q.

RESULTS

The WMS-R Logical Memory I and II and WASi Vocabulary tests were found to have the greatest number of scoring errors. Few substantive errors were detected on source document review of the MMSE, GDS, MAC-Q and WMS-R Verbal Paired Associates I. Some additional administration and scoring issues were identified during feedback sessions with the raters.

CONCLUSIONS

Cognitive measures used in clinical trials are prone to errors which can be detected with proper monitoring. Some instruments are particularly prone to inter-rater variably and should therefore be targets for focused training and ongoing monitoring. Areas in need of further investigation to help inform and optimize quality of clinical trial data are discussed.

Follistatin-like 3 is a mediator of exercise-driven bone formation and strengthening

Exercise is vital for maintaining bone strength and architecture. Follistatin-like 3 (FSTL3), a member of follistatin family, is a mechanosensitive protein upregulated in response to exercise and is involved in regulating musculoskeletal health. Here, we investigated the potential role of FSTL3 in exercise-driven bone remodeling. Exercise-dependent regulation of bone structure and functions was compared in mice with global Fstl3 gene deletion (Fstl3-/-) and their age-matched Fstl3+/+ littermates. Mice were exercised by low-intensity treadmill walking. The mechanical properties and mineralization were determined by μCT, three-point bending test and sequential incorporation of calcein and alizarin complexone. ELISA, Western-blot analysis and qRT-PCR were used to analyze the regulation of FSTL3 and associated molecules in the serum specimens and tissues. Daily exercise significantly increased circulating FSTL3 levels in mice, rats and humans. Compared to age-matched littermates, Fstl3-/- mice exhibited significantly lower fracture tolerance, having greater stiffness, but lower strain at fracture and yield energy. Furthermore, increased levels of circulating FSTL3 in young mice paralleled greater strain at fracture compared to the lower levels of FSTL3 in older mice. More significantly, Fstl3-/- mice exhibited loss of mechanosensitivity and irresponsiveness to exercise-dependent bone formation as compared to their Fstl3+/+ littermates. In addition, FSTL3 gene deletion resulted in loss of exercise-dependent sclerostin regulation in osteocytes and osteoblasts, as compared to Fstl3+/+ osteocytes and osteoblasts, in vivo and in vitro. The data identify FSTL3 as a critical mediator of exercise-dependent bone formation and strengthening and point to its potential role in bone health and in musculoskeletal diseases.

Review of medical discharge summaries and medical documentation in a metropolitan hospital: impact on diagnostic-related groups and Weighted Inlier Equivalent Separation

BACKGROUND

Accurate and comprehensive clinical documentation is crucial for effective ongoing patient care, follow up and to optimise case mix-based funding. Each Diagnostic Related Group (DRG) is assigned a 'weight', leading to Weighted Inlier Equivalent Separation (WIES), a system many public and private hospitals in Australia subscribe to.

AIMS

To identify the top DRG in a general medical inpatient service, the completeness of medical discharge documentation, commonly missed comorbidities and system-related issues and subsequent impact on DRG and WIES allocation.

METHODS

One hundred and fifty completed discharge summaries were randomly selected from the top 10 medical DRG in our health service. From a detailed review of the clinical documentation, principal diagnoses, associated comorbidities and complications, where appropriate, the DRG and WIES were modified.

RESULTS

Seventy-two (48%) of the 150 reviewed admissions resulted in a revision of DRG and WIES equivalent to an increase of AUD 142,000. Respiratory-based DRG generated the largest revision of DRG and WIES, while 'Cellulitis' DRG had the largest relative change. Twenty-seven per cent of summaries reviewed necessitated a change in coding with no subsequent change in DRG allocation or WIES. Acute renal failure, anaemia and electrolyte disturbances were the most commonly underrepresented entities in clinical discharge documentation. Seven patients had their WIES downgraded.

CONCLUSION

Comprehensive documentation of principal diagnosis/diagnoses, comorbidities and their complications is imperative to optimal DRG and WIES allocation. Regular meetings between clinical and coding staff improve the quality and timeliness of medical documentation, ensure adequate communication with general practitioners and lead to appropriate funding.

Curvularia lunata: a rare cause of black-grain eumycetoma

Curvularia lunata is a dematiaceous fungus that rarely causes cutaneous infections in immunocompetent humans. We describe a case of mycetoma pedis caused by Curvularia lunata in a 50-year-old woman from a rural farming community who had prolonged morbidity due to diagnostic delay. She improved with antifungal therapy, showing a satisfactory clinical response after 12 months of treatment.

Cutaneous phaeohyphomycosis due to Cladophialophora bantiana in an immunocompetent patient

We report the case of a 56-year-old Chinese woman with phaeohyphomycosis. She presented with a 4-year history of a recurring erythematous plague initially diagnosed as chromoblastomycosis on histopathological examination. Surgical excision was performed when the lesion recurred despite intial treatment response to itraconazole. Tissue cultures of the surgical specimen grew Cladophialophora bantiana. Treatment with terbinaffine post surgery was instituted with no recurrence of the lesion to date. Cutaneous phaeohyphomycosis caused by Cladophialophora bantiana is rare and this case highlights the clinical presentation, laboratory findings and treatment of this infection.

Is wheezing associated with decreased sleep quality in Sri Lankan children? A questionnaire study

AIM

To investigate the association between wheezing and impaired sleep in Sri Lankan children, aged 6-12 years; and, to report the prevalence of asthma-related symptoms in these subjects.

METHODS

The International Study of Asthma and Allergies in Childhood questionnaire and a separate sleep questionnaire were completed.

RESULTS

Of 800 originally distributed questionnaires, 652 were analyzed. Wheezing was present in 89 children (14%). Within this group, 66% reported wheezing in the last 12 months. Wheezing children had a significantly higher presence of snoring, restless sleep, nocturnal awakenings and daytime tiredness. Wheezing was found to be independently associated with restless sleep (odds ratio (OR) = 2.4). There was no association between wheezing and difficulties falling asleep, nocturnal awakenings, apneas, and daytime sleepiness and tiredness. After adjusting for possible confounders, the following significant associations were present: snoring and apneas (OR = 1.6), chronic rhinitis and apneas (OR = 1.6), snoring and restless sleep (OR = 3.2), chronic rhinitis and restless sleep (OR = 2.1), and hayfever and daytime tiredness (OR = 4.3). Wheezing was related to an increased risk of snoring (OR = 2.8) and subjects with chronic rhinitis had also an increased risk of snoring (OR = 1.7), adjusting for possible confounders.

CONCLUSION

The sleep of wheezing children was impaired compared with their non-wheezing peers, resulting in an increased prevalence of daytime tiredness. Upper airway symptoms, such as chronic rhinitis or hayfever, should be carefully considered in these children, as they might be responsible for these sleep problems.

An outbreak of Aspergillus meningitis following spinal anaesthesia for caesarean section in Sri Lanka: a post-tsunami effect?

An outbreak of Aspergillus fumigatus meningitis occurred in 5 women following spinal anaesthesia, performed between 21 June and 17 July 2005 for caesarean section, in Colombo, Sri Lanka. The patients' median age was 27 years. Different teams in 2 maternity hospitals gave spinal anaesthesia. Mean incubation period was 11.2 days. Fever, headache and nuchal rigidity were common presentations. Remittent fever continued despite broad-spectrum intravenous antibiotics. Papilloedema, lateral rectus palsy, cerebral infarction and haemorrhage developed later. Three patients died. Cerebrospinal fluid pleocytosis with low glucose yielded negative PCR for fungi. Fungal cultures subsequently grew Aspergillus fumigatus. A post-mortem of the first patient confirmed Aspergillus meningitis, followed by treatment with amphotericin B and voriconazole, that saved the lives of others. Visual and hearing impairment in one and complete recovery in the other were observed a year after treatment. Examination of unused plastic syringes, needles, cannulae, and ampoules of anaesthetic agents confirmed that 43 syringes from three different manufactures were contaminated with Aspergillus fumigatus. The stores for drugs and devices of the Ministry of Health were examined and found to be full of tsunami donations, while regular procurements of the Ministry were kept in a poorly maintained humid warehouse. Inadequate space for tsunami donations was identified as the most plausible explanation for sub-optimal storage. Withdrawal and incineration of all unused syringes controlled the outbreak. The survival of those aggressively treated for Aspergillus meningitis suggests in hindsight that the availability of diagnostic tests and specific treatment, and early recognition of the outbreak could have saved the lives of victims who died. Early life-threatening side-effects and permanent long term sequelae of antifungal medication stress the need to be cautious with empirical treatment in immuno-competent low-risk individuals.

Scars of torture: A Sri Lankan study

Interpretation of scars of torture is not an easy task as our understanding of evolution of scars of different methods of torture is still in its infancy. The objectives of this study were to produce the features of a typical scar of a few selected methods of torture and determine their characteristic distribution. To achieve this, 100 medico-legal records of victims of torture examined at the Judicial Medical Officer's Office, Colombo between 1998 and 2001 were perused. Scars caused by seven selected methods of torture were taken into consideration. They were, assault with both non-pliable and pliable blunt objects, cigarette burns, burns with heated solid objects and molten plastic, ligature application with different forms of suspension and cuts with sharp objects. Total number of scars analyzed in this study was 1846, which included 740 scars of non-pliable blunt weapons, 182 of pliable blunt weapons, 102 of ligature, 59 of molten polythene, 55 of heated objects and 82 of razor blades and knives. Typical scars of each method of torture and their characteristic distribution were determined.

Physical methods of torture and their sequelae: a Sri Lankan perspective

Methods of torture vary from country to country and sometimes within regions in the same country. Knowing torture methods used in a country or region assists in evaluating injuries, scars and other chronic sequelae of torture. Medical records of 100 victims of torture examined between 1998 and 2001 in the Judicial Medical Officer's Office in Colombo, Sri Lanka, were perused to gather data on torture methods used in Sri Lanka during that period. Altogether 68 methods of torture had been used on these victims. They included assault with blunt and sharp weapons, burns with lighted cigarettes, 'dry submarino', kicking, 'wet submarino', 'hanging', electric torture, 'falaka' and many more. However, only 18% of victims had any physical residual effects, highlighting the typical objective of torture, which is inflicting maximum pain without causing serious injury or death.

Screening of ubiquitous plant constituents for COX-2 inhibition with a scintillation proximity based assay

A rapid semi-homogeneous cyclooxygenase-2 (COX-2) enzymatic assay using scintillation proximity assay (SPA) technology was developed, and 49 ubiquitous plant secondary metabolites were screened for inhibition of COX-2-catalyzed prostaglandin E(2) (PGE(2)) biosynthesis. Assay conditions were optimized with respect to reaction time, amount of antibody, radiolabeled PGE(2), and SPA beads, and the kinetic parameter, K(m), was estimated. The assay was validated with two natural triterpenoids, ursolic and oleanolic acid, known to inhibit COX-2, as well as with four synthetic COX inhibitors, NS-398, rofecoxib, indomethacin, and aspirin. Plant metabolites of different biosynthetic origin representing several substance classes, including alkaloids, anthraquinones, flavonoids, phenylpropanes, steroids, and terpenes, were screened for inhibition of COX-2-catalyzed PGE(2) production. Of these 49 plant metabolites, eugenol, pyrogallol, and cinnamaldehyde (with IC(50) values of 129, 144, and 245 microM, respectively) were found to inhibit COX-2. This study showed that a COX-2-catalyzed PGE(2) assay using SPA is suitable for screening natural compounds with respect to COX-2 inhibition.

Cox-2 inhibitory effects of naturally occurring and modified fatty acids

In the search for new cyclooxygenase-2 (COX-2) selective inhibitors, the inhibitory effects of naturally occurring fatty acids and some of their structural derivatives on COX-2-catalyzed prostaglandin biosynthesis were investigated. Among these fatty acids, linoleic acid (LA), alpha-linolenic acid (alpha-LNA), myristic acid, and palmitic acid were isolated from a CH(2)Cl(2) extract of the plant Plantago major by bioassay-guided fractionation. Inhibitory effects of other natural, structurally related fatty acids were also investigated: stearic acid, oleic acid, pentadecanoic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Further, the inhibitory effects of these compounds on COX-2- and COX-1-catalyzed prostaglandin biosynthesis was compared with the inhibition of some synthesized analogues of EPA and DHA with ether or thioether functions. The most potent COX-2-catalyzed prostaglandin biosynthesis inhibitor was all-(Z)-5-thia-8,11,14,17-eicosatetraenoic acid (2), followed by EPA, DHA, alpha-LNA, LA, (7E,11Z,14Z,17Z)-5-thiaeicosa-7,11,14,17-tetraenoic acid, all-(Z)-3-thia-6,9,12,15-octadecatetraenoic acid, and (5E,9Z,12Z,15Z,18Z)-3-oxaheneicosa-5,9,12,15,18-pentaenoic acid, with IC(50) values ranging from 3.9 to180 microM. The modified compound 2 and alpha-LNA were most selective toward COX-2, with COX-2/COX-1 ratios of 0.2 and 0.1, respectively. This study shows that several of the natural fatty acids as well as all of the semisynthetic thioether-containing fatty acids inhibited COX-2-catalyzed prostaglandin biosynthesis, where alpha-LNA and compound 2 showed selectivity toward COX-2.

Anti-inflammatory activity of dichloromethane extract of Heterotheca inuloides in vivo and in vitro

The dichloromethane extract from the dried flowers of Heterotheca inuloides Cass. was investigated on several pharmacological models of inflammation in vivo and in vitro. It showed anti-inflammatory activity on the croton oil-induced oedema test in mouse ear, at 1 mg/ear. The compound isolated from this extract, 7-hydroxy-3,4-dihydrocadalin, showed anti-inflammatory effect on the same experimental model (ED50 of 0.9 mumol/ear), as well as on COX-1 and COX-2 catalysed prostaglandin biosynthesis assays, with IC50 values of 22 microM and 526 microM, respectively. No effect was observed on carrageenan-induced oedema and on fMLP/PAF-induced exocytosis of human neutrophils. The COX-1 inhibitory effect showed by 7-hydroxy-3,4-dihydrocadalin might be related to the anti-inflammatory activity on the topical oedema induced by croton oil.

Ursolic acid from Plantago major, a selective inhibitor of cyclooxygenase-2 catalyzed prostaglandin biosynthesis

A hexane extract of Plantago major was investigated by bioactivity-directed fractionation, using an in vitro cyclooxygenase-2 (COX-2) catalyzed prostaglandin biosynthesis inhibition assay, and resulted in the isolation of ursolic acid (1). This triterpenoid showed a significant COX-2 inhibitory effect, directly on the enzyme activity, with an IC50 value of 130 microM and a COX-2/COX-1 selectivity ratio of 0.6. The structural isomer oleanolic acid (2) was found to be less active than 1, with an IC50 value of 295 microM, but showed a similar selectivity ratio (0.8). Furthermore, no significant inhibition on COX-2 or COX-1 was observed by the triterpenoid, 18beta-glycyrrhetinic acid (3). The direct inhibitory effect of 1 and 2 on COX-2 catalyzed prostaglandin biosynthesis increased with preincubation, indicating a time-dependent inhibition, while the effect on COX-1 was found to be independent of preincubation time.

Flavan-3-ols isolated from some medicinal plants inhibiting COX-1 and COX-2 catalysed prostaglandin biosynthesis

Extracts from the four plant species Atuna racemosa Raf. ssp. racemosa, Syzygium corynocarpum (A. Gray) C. Muell., Syzygium malaccense (L.) Merr. & Perry and Vantanea peruviana Macbr., traditionally used for inflammatory conditions, were fractionated using a cyclooxygenase-1 catalysed prostaglandin biosynthesis in vitro assay. The flavan-3-ol derivatives (+)-catechin, (+)-gallocatechin, 4'-O-Me-ent-gallocatechin, ouratea-catechin and ouratea-proanthocynidin A were isolated as active principles. The IC50 values ranged from 3.3 microM to 138 microM whilst indomethacin under the same test conditions had an IC50 value of 1.1 microM. The flavonol rhamnosides mearnsitrin, myricitrin and quercitrin were also isolated. When further tested for inhibitory effect on cyclooxygenase-2 catalysed prostaglandin biosynthesis, the five flavan-3-ol derivatives exhibited from equal to weaker inhibitory potencies, as compared to their cyclooxygenase-1 inhibitory effects. The flavonol rhamnosides were inactive towards both enzymes.

Alphitol, a phenolic substance from Alphitonia zizyphoides which inhibits prostaglandin biosynthesis in vitro

The new phenolic compound, 3,5-dihydroxy-4-methoxy phenethyl alcohol, named alphitol, and betulinic acid were from the bark of Alphitonia zizyphoides. The chemical structure of alphitol was determined by mass spectrometry in combination with one and two dimensional NMR, including HMBC. Both compounds inhibited prostaglandin biosynthesis in vitro, alphitol with an IC50 value of 0.66mM, which is of the same magnitude as acetyl salicylic acid.

Amentoflavone from Biophytum sensitivum and its effect on COX-1/COX-2 catalysed prostaglandin biosynthesis

Amentoflavone (I3', II8-biapigenin) was isolated from the roots of Biophytum sensitivum DC. (Oxalidaceae) and proved to be a selective inhibitor of cyclooxygenase (COX)-1 catalysed prostaglandin biosynthesis when tested in vitro with an IC (50) value of 12.4 microM (standard: indomethacin, IC (50) = 1.1 microM). Doses of up to 37 microM showed only a slight inhibition in the corresponding COX-2 assay. Quantification of amentoflavone was carried out by reversed phase HPLC in methanolic and aqueous extracts of the roots, stems and leaves. Highest amounts of amentoflavone were detected in methanolic extracts of roots and stems (0.26-0.35%), while considerably lower amounts were detected in the corresponding water extracts.

Two new isoflavones from Ceiba pentandra and their effect on cyclooxygenase-catalyzed prostaglandin biosynthesis

The new isoflavone glucoside vavain 3'-O-beta-d-glucoside (1) and its aglycon, vavain (2), were isolated from the bark of Ceiba pentandra, together with the known flavan-3-ol, (+)-catechin, These novel structures were elucidated by one- and two-dimensional NMR experiments and by MS, IR, and UV spectroscopy as 5-hydroxy-7,4',5'-trimethoxyisoflavone 3'-O-beta-D-glucoside (1) and 5,3'-dihydroxy-7,4',5'-trimethoxyisoflavone (2), respectively. The compounds were isolated following bioactivity-directed fractionation, using a cyclooxygenase-1-catalyzed prostaglandin biosynthesis assay in vitro, in which compounds 1 and 2 and (+)-catechin exhibited IC50 values of 381, 97, and 80 microM, respectively (standard: indomethacin, IC50 1,1 microM). When further tested for their inhibitory effects on cyclooxygenase-2-catalyzed prostaglandin biosynthesis, 1 and 2 were found to be inactive (IC50 > 1200 and > 900 microM, respectively).

Development of a radiochemical cyclooxygenase-1 and -2 in vitro assay for identification of natural products as inhibitors of prostaglandin biosynthesis

A radiochemical enzyme assay for studying cyclooxygenase (COX)-catalyzed prostaglandin biosynthesis in vitro was optimized with respect to both COX-1 and COX-2 activity. The assay can be used to assess the relative selectivity of plant-derived inhibitors on COX-1 and COX-2 Assay conditions were optimized for both enzymes with respect to concentration of cofactors (l-epinephrine, reduced glutathione, and hematin), activation time (enzyme and cofactors), reaction time, and pH. Moreover, the kinetic parameters, Km and Kcat, of both enzymes were estimated. Five COX inhibitors were used to validate the assay, indomethacin, aspirin, naproxen, ibuprofen, and the arylsulfonamide NS-398, all with different COX selectivity and time dependency. Time-dependent inhibition was determined by comparing the inhibition, with and without preincubation of enzyme and inhibitor. Two flavonoids, (+)-catechin and quercitrin, were examined with respect to inhibition of COX-catalyzed prostaglandin biosynthesis. (+)-Catechin showed equal inhibitory effects on the two enzymes. Quercitrin was found to be inactive toward both COX-1- and COX-2-catalyzed prostaglandin biosynthesis. The optimization procedure resulted in a considerable reduction of the amount of enzyme required for adequate prostglandin biosynthesis and a reliable method suited to evaluate natural products on inhibition of COX-2-catalyzed prostaglandin biosynthesis, as well as on COX-1.

Evaluation of some Samoan and Peruvian medicinal plants by prostaglandin biosynthesis and rat ear oedema assays

In our ongoing program to find new anti-inflammatory compounds, 58 extracts from 46 different medicinal plant species, used in treatment of inflammatory disorders-38 plants from the traditional medicine of Western Samoa and eight originating from the indigenous medicine of the Shipibo-Conibo tribe of Peruvian Amazonia-ere evaluated. The ability of all extracts to inhibit cyclooxygenase-1 catalysed prostaglandin biosynthesis in vitro was examined. Of the plant species tested 14 showed moderate to strong inhibition; including 11 Samoan and three Peruvian species. Further, 12 Samoan and all eight Peruvian species were investigated on their inhibitory activity of ethyl phenylpropiolate induced rat ear oedema in vivo. Significant activity was shown by 10 of the Samoan and by all eight Peruvian species. An additional evaluation of the most active species was provided through a compilation of existing literature documenting traditional medicinal uses, pharmacological activity and chemical constituents. Several known cyclooxygenase-1 inhibitors were reported to which the observed pharmacological activity can be attributed at least partly. The combination of chemical and pharmacological literature data and our experimental data may help to explain the anti-inflammatory use of these species in indigenous medicine.

Exposure of human CD34+ cells to human immunodeficiency virus type 1 does not influence their expansion and proliferation of hematopoietic progenitors in vitro

The susceptibility of highly purified human CD34+ cells to monocytotropic (Ba-L) and lymphotropic (A018-post) strains of human immunodeficiency virus-1 (HIV-1) was examined. Liquid cultures initiated with fresh immunomagnetically purified CD34+ cells using the K6.1 CD34 monoclonal antibody (MoAb) (K6.1/CD34+) were positive for HIV expression 2 weeks after exposure to HIV-1 Ba-L. These cells were initially greater than 90% CD34+ and had undetectable monocyte contamination by flow-cytometric staining and side-scatter analyses, respectively, and undetectable T-cell contamination by CD3 polymerase chain reaction (PCR) analysis. However, secondary CD34+ liquid cultures reselected from the primary liquid cultures 24 hours after HIV exposure by panning with the ICH3 CD34 MoAb (ICH3/CD34+) and maintained for an additional 14 days were negative for HIV expression. The ICH3-unbound cells were positive for both spliced and unspliced HIV RNA when exposed to HIV-1 Ba-L, and were DNA PCR positive when exposed to either monocytotropic or lymphotropic HIV-1. To further test that CD34+ cells were not infectible by HIV-1, we exposed K6.1/CD34+ cells continuously to HIV-1 in a culture system capable of maintaining and expanding primitive CD34+ cells. HIV-exposed K6.1/CD34+ cells proliferated and expanded as efficiently as uninfected cultures. However, when reselected magnetically using the K6.1 CD34 MoAb after expansion for 7 days, bound K6.1/CD34+ cells were again negative for HIV-1 expression, whereas unbound cells were positive for HIV-1 expression. These findings suggest that a sequential CD34+ cell-selection process, in which the two selections are separated by a brief culture period, can yield a population of CD34+ cells that are not infected with HIV-1. This process may be useful in the design of stem or progenitor cell-based transplantation therapies for HIV infection.

Isolation of two new antiinflammatory biflavanoids from Sarcophyte piriei

Two new flavano flavanone glycosides, diinsininol (1) and diinsinin (2), have been isolated from the rhizome of Sarcophyte piriei, together with one known flavanone glycoside, naringenin 5-glucoside. Their structures were elucidated on spectroscopic evidence as 5,7,3',4'-tetrahydroxyflavanyl-7-O-beta-glucosyl-(4beta-8; 2beta-O-7)-eriodietyol (1) and 5,7,3',4'-tetrahydroxyflavanyl 7-O-beta-glucosyl-(4beta-8;2beta-O-7)-naringenin (2), respectively. The compounds were tested for their ability to inhibit prostaglandin synthesis, with 1 and 2 giving IC50 values of 9.20 microM and 13.14 microM, respectively, and in the inhibition of platelet-activating-factor-induced exocytosis, IC50 values of 49 and 39 microM.

Abnormal TCR V beta repertoire in patients with chronic myeloid leukaemia

We have used 25 sets of oligonucleotide primers specific for the 24 known major human T-cell receptor (TCR) V beta families in polymerase chain reactions to analyse the T-cell repertoire of the peripheral blood in seven patients with chronic myeloid leukaemia (CML). In contrast to normal healthy individuals, all seven patients exhibited variable degrees of TCR V beta-specific T-cell deletion, ranging from two to eight of the 24 major families. T cells bearing V beta 17 and 8 were most commonly deleted. These results suggest a superantigen effect associated with CML. The patterns of deletion did not appear to correlate with either of the two bcr-abl transcripts. The reason and aetiological agent responsible for the T-cell deletion remain speculative. Further work is ongoing to characterize this phenomenon in animal models and patients with CML.

Structure elucidation of three triterpenoid saponins from Alphitonia zizyphoides using 2D NMR techniques

High-field nmr experiments have been used to determine the structures of three new saponins, zizyphoisides C, D, and E [1-3], isolated from Alphitonia zizyphoides, a medicinal plant found in the Samoan rain forest. The saponins consist of the aglycone, jujubogenin, to which are attached three sugar units and an unsaturated side-chain. The three compounds are similar except for the location of an acetyl group on one of the sugar units.

Subsets of CD8+, CD57+ cells in normal, healthy individuals: correlations with human cytomegalovirus (HCMV) carrier status, phenotypic and functional analyses

Two different subsets of CD8+, CD57+ cells have been defined, one expressing high levels (CD8high+(CD57+)), the other expressing low levels of surface CD8 (CD8low+(CD57+)). Increased numbers of CD8high+(CD57+) cells correlated with previous HCMV infection. By three-colour fluorescence analysis, the CD8high+(CD57+) population expressed T cell markers such as CD3 and CD5, and most were alpha beta T cell receptor (alpha beta TCR)-positive. A significant proportion also expressed CD71 (transferrin receptor) and MHC class I, although little if any CD25 (IL-2R-p55). Some (> or = 40%) co-expressed CD45RA and CD45RO. The CD8low+(CD57+) population expressed classical natural killer (NK) cell markers--CD2, CD16 and CD56. The two subsets were also functionally distinct; CD8high+(CD57+) cells suppressed pokeweed mitogen (PWM)-driven, but not phytohaemagglutinin (PHA)-driven proliferation and immunoglobulin production; CD8low+(CD57+) cells exhibited NK cytotoxic activity which was not increased by interferon-alpha (IFN-alpha). Supernatant from cultured CD8high+(CD57+) cells suppressed PWM-driven immunoglobulin production, but not proliferation, and this effect was abrogated by physical separation with tissue culture inserts. Thus, a T cell subset expressing activation and memory T cell markers with direct non-specific suppressor activity was present in peripheral blood mononuclear cells (PBMC) of healthy subjects with asymptomatic HCMV infection.

Assignment of human ferritin genes to chromosomes 11 and 19q13.3----19qter

Extracts of hamster-human and mouse-human hybrids, some with translocations involving chromosome 19, have been assayed for both human spleen ferritin (rich in L subunits) and human heart ferritin (rich in H subunits). Hybrid lines retaining part of the long arm of chromosome 19 including the region 19q13.3----19qter produced human "L" type ferritin. This confirms the previous assignment of the "ferritin gene" to chromosome 19 (Caskey et al. 1983). However, lines retaining chromosome 11 were found to contain human "H" type ferritin suggesting that the gene for the "H" subunit is on this chromosome. The presence of chromosome 6 was not necessary for the expression of either "H" or "L" type human ferritin. It thus seems unlikely that the gene for idiopathic haemochromatosis is a ferritin gene.

A single-step immunoradiometric assay for the measurement of serum ferritin

An immunoradiometric assay (IRMA) which can be carried out in a single working day is described here. The assay is comparable to the conventional IRMA with respect to both sensitivity and reproducibility and is less labour intensive.

Antigen binding in the two-site immunoradiometric assay for serum ferritin: the nature of the hook effect

The two stages of a two-site immunoradiometric assay were investigated separately. In the first stage, the amount of ferritin bound to coated tubes initially showed a rapid increase with increasing concentration of added ferritin. This was followed by a plateau and then a further increase which appeared to be largely due to non-specific binding. During the second stage, a significant proportion of the bound ferritin dissociated from the solid phase and sequestered some of the labelled antibody in solution. Thus less antibody was available to bind to ferritin attached to the tube, causing a decrease in count rate at high ferritin concentrations. The use of a monoclonal antibody for coating the tubes did not eliminate this hook effect.

Dichomine, a novel type of iboga alkaloid*,**

From the leaves of TABERNAEMONTANA DICHOTOMA and the leaves and twigs of T. EGLANDULOSA a new alkaloid was isolated which was assigned structure 1 on the basis of spectroscopic and chemical evidence.

Tertiary indole alkaloids from leaves of Tabernaemontana dichotoma

Seven indole alkaloids were isolated and identified from the leaves of Tabernaemontana dichotoma Roxb. The major alkaloids were: perivine, 19-epi-voacristine, 12-methoxy-voaphylline and vobasine. (-)apparicine, 19-epi-iboxygaine and isomethuenine occurred in minor amounts.

Studies in desferrioxamine and ferrioxamine metabolism in normal and iron-loaded subjects

Plasma concentrations of desferrioxamine and ferrioxamine were measured following bolus injections of desferrioxamine and during 24 h infusions of the drug. [59Fe]ferrioxamine clearance and urinary iron excretion were also measured. Higher plasma ferrioxamine concentrations were found in iron loaded subjects and higher desferrioxamine concentrations in subjects with normal ironloads. There is a correlation between the circulating concentration of ferrioxamine during an infusion and the 48 h urinary iron excretion. The data suggests that the amount of iron chelated in vivo is related to an increase in the size of an intermediate chelatable pool rather than the total amount of the iron load. The well-recognized delay in urinary iron excretion appears to be related to active tubular reabsorption of ferrioxamine.

Iron overload in Chang cell cultures: biochemical and morphological studies

Cultures of Chang cells have been studied during growth in media supplemented with ferric nitriloacetate. Iron loading of the cells occurs rapidly and is related to the iron concentration in the medium. A 50-fold increase in cellular iron content was obtained in some cultures. Most of the intracellular iron is membrane-bound and is seen on electron microscopy to be concentrated in discrete bodies. There is a rapid rise in cellular ferritin content after exposure to iron. Most of this is found in the cytosol.

Iron taken into the cells is found equally in the cytosol and associated with membranes for the first 4 days of culture. After this time there is a rapid rise of membrane-bound iron associated with the formation of siderosomes which contain iron-rich ferritin cores. These siderosomes later evolve to contain irregular, electron-dense accumulations of iron.

Initial exposure of cells to high iron concentrations causes rapid death but similar exposure after ferritin synthesis and siderosome formation has been stimulated by low iron concentrations is well tolerated. Cultures have been maintained for up to 26 weeks with no morphological signs of toxicity, though there is some impairment of proliferation at high iron concentrations. It is suggested that siderosome formation is part of the mechanism that protects the cell against iron toxicity.