Iodine status among pregnant women in Kuwait

Up to now, little has been known about iodine intake and the prevalence of iodine deficiency (ID), if any, in Kuwait. Urinary iodine excretion (UIE) and changes in thyroid function during pregnancy were thus evaluated.

METHODS

Urinary iodide level was measured in random urine samples collected from 326 pregnant women at different gestational trimesters. Blood samples were drawn for free T4 (FT4) and TSH level determination.

RESULTS

Median UIE levels fall within the normal range during all gestational trimesters i.e. >100 microg/l. However, if the new suggested recommendation for pregnant women <140 microg/l, is applied, median UIE values during trimesters 2 and 3 indicate ID. Mean serum TSH levels increased between trimesters 1 and 3 (p<0.05), whereas serum FT4 decreased between first and second trimesters (p<0.05), and this reduction continued at the third trimester. Furthermore, an increase in TSH levels for subjects with mild and moderate ID (Mi and Mo, respectively) were noticed (p<0.05) during the second trimester. However, FT4 levels dropped in subjects with Mi and Mo ID during the first trimester (p<0.05). In conclusion, these results suggest that 56.8% of pregnant women had median UIE level <145 microg/l, associated with high TSH and low FT4 levels.

CONCLUSION

Data obtained may indicate insufficient iodine intake among pregnant women in Kuwait.

Mutually exclusive NRASQ61R and BRAFV600E mutations at the single-cell level in the same human melanoma

Activating BRAF or NRAS mutations have been found in 80% of human sporadic melanomas, but only one of these genetic alterations could be detected in each tumour. This suggests that BRAF and NRAS 'double mutants' may not provide advantage for tumour growth, or may even be selected against during tumorigenesis. However, by applying mutant-allele-specific-amplification-PCR method to short-term melanoma lines, one out of 14 tumours was found to harbour both BRAFV600E and the activating NRASQ61R mutations. On the other hand, analysis of 21 melanoma clones isolated by growth in soft agar from this tumour indicated that 16/21 clones harboured a BRAFV600E, but were wild-type for NRAS, whereas the remaining had the opposite genotype (NRASQ61R/wild-type BRAF). When compared to BRAFV600E clones, NRASQ61R clones displayed reduced growth in soft agar, but higher proliferative ability in vitro in liquid medium and even in vivo after grafting into SCID/SCID mice. These data suggest that NRAS and BRAF activating mutations can coexist in the same melanoma, but are mutually exclusive at the single-cell level. Moreover, the presence of NRASQ61R or BRAFV600E is associated with distinct in vitro and in vivo growth properties of neoplastic cells.

[Sciatica secondary to a presacral abscess as the first manifestation of Crohn's disease]

Presacral abscess is a rare musculoskeletal complication of Crohn's disease. The clinical picture is sometimes insidious and a delay in diagnosis may increase morbidity. Abdominal-pelvic computerized axial tomography (CAT) has proven to be very useful in the diagnosis of this entity, which usually requires surgical treatment. We present the case of a 22-year-old man who presented to hospital for colic-type abdominal pain of 6 months' evolution and intermittent episodes of joint pain. The patient also presented mechanical pain in the right gluteus muscle of two weeks' evolution irradiating to the posterior side of the muscle. Complementary investigations confirmed the suspected diagnosis of Crohn's disease and showed presacral abscess. Treatment was surgical.

Selection and characterization of varicella-zoster virus variants resistant to (R)-9-[4-hydroxy-2-(hydroxymethy)butyl]guanine

(R)-9-[4-Hydroxy-2-(hydroxymethy)butyl]guanine (H2G) is a potent and selective inhibitor of herpesvirus replication. It is a nucleoside analog, and its triphosphate derivative (H2G-TP) is a competitive inhibitor of herpesvirus DNA polymerases. In this study, the antiviral activities of H2G and acyclovir (ACV) and the development of viral resistance to these agents were compared in varicella-zoster virus (VZV)-infected cells. In plaque reduction assays, the 50% effective concentration of H2G for VZV was 60- to 400-fold lower than that of ACV, depending on the virus strain and the cell line tested. The enhanced efficacy of H2G against VZV can be accounted for in part by the fact that the intaracellular H2G-TP level (>170 pmol/10(6) cells) is higher than the intracellular ACV-TP level (<1 pmol/10(6) cells). In addition, H2G-TP has extended half-lives of 3.9 and 8.6 h in VZV-infected MRC-5 and MeWo cells, respectively. To assess the emergence of H2G-resistant VZV in vitro, VZV was passaged in the presence of increasing concentrations of H2G. Earlier in the passage, when the concentration of H2G was relatively low, the predominant variant had the (A)76 deletion in the viral thymidine kinase (TK) gene. This mutant was identical to an ACV-resistant mutant generated in parallel experiments. However, higher concentrations of H2G appeared to favor a novel mutant, which had deletions of two consecutive nucleotides at positions 805 and 806 of the TK gene. All of these changes introduced frameshift mutations in the TK gene resulting in the expression of truncated polypeptides. H2G-resistant viruses were cross-resistant to ACV, and vice versa.

Comparison of safety of glucose oral rehydration solution and maize oral rehydration therapy for home management of diarrhoea in Kenya

Safety margins and variability in the composition of glucose and maize-based oral rehydration therapy (ORT) prepared by mothers in a rural district of Western Kenya, are reported here. In a 2-year longitudinal field study, packets containing glucose ORS and a home solution made with maize and table salts, were provided to the mothers of 6180 children in Kakamega District in two separate sub-locations. Experienced and trained field workers supported by community registered nurses provided training for the preparation and use of ORT during weekly visits to every household. On four occasions separated by 4-6 months, a 5 per cent random sampling was done of the home-prepared solutions actually used for the treatment of children with diarrhoea. The water used for preparing ORT was also sampled. Samples of 174 glucose-based ORT, 148 maize-salt ORT, and 201 samples of water were analysed. Only 2 per cent of the maize-based ORT were above 120 meq/1 sodium (i.e., the safe range of sodium concentration) compared to 17.8 per cent for glucose solutions (p < 0.001). Home water samples contained substantial amounts of salt, which could unpredictably affect the final composition of the ORT solutions. We conclude that maize-salt ORT had a better margin of safety than glucose-based ORS.

Synthesis and antiviral activities of the major metabolites of the HIV protease inhibitor ABT-378 (Lopinavir)

The HIV protease inhibitor ABT-378 (Lopinavir) is metabolized rapidly and extensively by CYP-3A4 catalyzed oxidation. Three of the major metabolites identified were synthesized and their antiviral (HIV) activities determined.

Adherence of human erythroleukemia cells inhibits proliferation without inducing differentiation

To investigate the effect of extracellular matrix molecules in the megakaryocytic lineage, we studied the role of integrin engagement in the proliferation and differentiation of human erythroleukemia (HEL) cells. HEL cells grew in suspension, but their adherence depended upon the presence of matrix proteins or protein kinase C signaling. Adherence by itself did not trigger commitment of these cells but accelerated phorbol 12-myristate 13-acetate-induced differentiation. HEL cells adhered to fibronectin mainly through alpha5beta1, and this receptor acted synergetically with alpha4beta1. Integrin engagement induced cell growth arrest through mitogen-activated protein kinase inactivation. Such down-regulation of the mitogen-activated protein kinase pathway by integrin engagement was suggested as a megakaryocytic-platelet lineage specificity. This signaling was not restricted to a peculiar integrin but was proposed as a general mechanism in these cells.

Grafting an RGD motif onto an epidermal growth factor-like module: chemical synthesis and functional characterization of the chimeric molecule

A novel protein was engineered by inserting the GRGDS motif of fibronectin within the 14-residue loop of the EGF-like module from human complement protease C1r. The resulting chimeric EGF-RGD module (52 residues, three disulfide bridges) was assembled by automated solid-phase synthesis using the t-Boc strategy. Using reduced/oxidized glutathione, the EGF-RGD module was folded as efficiently as the natural C1r-EGF module, resulting in formation of the appropriate disulfide bridge pattern as shown by mass spectrometry and N-terminal sequence analyses of thermolytic fragments. Circular dichroism and NMR measurements provided further indication that introduction of the GRGDS motif had no significant effect on the folding. Using Chinese Hamster Ovary (CHO) cells bearing the integrin receptors specific for fibronectin and vitronectin, EGF-RGD was shown to induce cell adhesion via the introduced GRGDS motif. Cell binding was inhibited specifically and efficiently by the synthetic peptide GRGDSP and by fibronectin, and to a much lesser extent by vitronectin, whereas the monoclonal antibody PB1 directed to the alpha5 subunit of alpha5beta1 integrin had no effect. The ability of EGF-RGD to trigger significant cell spreading and intracellular signaling was also demonstrated using immunofluorescence and confocal microscopy.

An expanded peripheral T cell population to a cytotoxic T lymphocyte (CTL)-defined, melanocyte-specific antigen in metastatic melanoma patients impacts on generation of peptide-specific CTLs but does not overcome tumor escape from immune surveillance in metastatic lesions

It is not known if immune response to T cell-defined human histocompatibility leukocyte antigen (HLA) class I-restricted melanoma antigens leads to an expanded peripheral pool of T cells in all patients, affects cytotoxic T lymphocyte (CTL) generation, and correlates with anti-tumor response in metastatic lesions. To this end, a limiting dilution analysis technique was developed that allowed us to evaluate the same frequency of peptide-specific T cells as by staining T cells with HLA-peptide tetrameric complexes. In four out of nine patients, Melan-A/Mart-1(27-35)-specific CTL precursors (CTLp) were >/=1/2,000 peripheral blood lymphocytes and found mostly or only in the CD45RO(+) memory T cell subset. In the remaining five patients, a low (<1/40,000) peptide-specific CTLp frequency was measured, and the precursors were only in the CD45RA(+) naive T cell subset. Evaluation of CTL effector frequency after bulk culture indicated that peptide-specific CTLs could be activated in all patients by using professional antigen-presenting cells as dendritic cells, but CTLp frequency determined the kinetics of generation of specificity and the final number of effectors as evaluated by both limiting dilution analysis and staining with HLA-A*0201-Melan-A/Mart-1 tetrameric complexes. Immunohistochemical analysis of 26 neoplastic lesions from the nine patients indicated absence of tumor regression in most instances, even in patients with an expanded peripheral T cell pool to Melan-A/Mart-1 and whose neoplastic lesions contained a high frequency of tetramer-positive Melan-A/Mart-1-specific T cells. Furthermore, frequent lack of a "brisk" or "nonbrisk" CD3(+)CD8(+) T cell infiltrate or reduced/absent Melan-A/Mart-1 expression in several lesions and lack of HLA class I antigens were found in some instances. Thus, expansion of peripheral immune repertoire to Melan-A/Mart-1 takes place in some metastatic patients and leads to enhanced CTL induction after antigen-presenting cell-mediated selection, but, in most metastatic lesions, it does not overcome tumor escape from immune surveillance.

Extracellular matrix receptors and the differentiation of human megakaryocytes in vitro

We investigated the expression and functions of extracellular matrix receptors (or integrins) in the course of the differentiation of human megakaryocytes (Mks) leading to the formation of platelets. Integrins beta1 or Very Late Antigens (VLA) are specialized transmembrane receptors allowing the attachment of the cells to collagen (VLA-2), fibronectin (VLA-4 and -5) and laminin (VLA-6). A proportion of committed megakaryocytic progenitor cells (CFU-MK) adhere to fibronectin but not to collagen or laminin. The early immature Mks are retained on fibronectin (30%) and laminin (12%) but not on collagen whereas large mature Mks are still adherent to fibronectin and laminin and also acquired the capacity to adhere to collagen. The expression of the different VLA in the maturation of Mks correlates well with their adhesive properties. Hence, VLA-2 is not expressed on immature Mks but is present on the mature polyploid cells. VLA-4 is detected only on immature Mks which do not seem to bear VLA-5, while this last integrin appears on late Mks. VLA-6 showed a broad distribution from the early to late stages of Mks differentiation. Integrins beta3 of the cytoadhesin family are represented by alphaIIb beta3 that is the receptor for fibrinogen and alphaV beta3 which mediates adhesion to vitronectin. AlphaIIb beta3 is present on the CFU-MK and highly expressed throughout the Mks maturation stages while alphaV beta3 expression is much lower and seems to be detected only on the late Mks. The regulation of the expression of these receptors by cytokines and their respective roles in the maturation of Mks and the final production of platelets, are discussed. The development of efficient culture systems of human Mks in the presence of the recently cloned thrombopoietin will undoubtedly help to shed more light on the molecular mechanisms of their interactions via integrins with the BM microenvironment.

Use of a fluorescence plate reader for measuring kinetic parameters with inner filter effect correction

A general method is presented here for the determination of the Km, kcat, and kcat/Km of fluorescence resonance energy transfer (FRET) substrates using a fluorescence plate reader. A simple empirical method for correcting for the inner filter effect is shown to enable accurate and undistorted measurements of these very important kinetic parameters. Inner filter effect corrected rates of hydrolysis of a FRET peptide substrate by hepatitis C virus (HCV) NS3 protease at various substrate concentrations enabled measurement of a Km value of 4.4 +/- 0.3 microM and kcat/Km value of 96,500 +/- 5800 M-1 s-1. These values are very close to the HPLC-determined Km value of 4.6 +/- 0.7 microM and kcat/Km value of 92,600 +/- 14,000 M-1 s-1. We demonstrate that the inner filter effect correction of microtiter plate reader velocities enables rapid measurement of Ki and Ki' values and kinetic inhibition mechanisms for HCV NS3 protease inhibitors.

Potent piperazine hydroxyethylamine HIV protease inhibitors containing novel P3 ligands

The 2-isopropyl thiazolyl group is a highly optimized P3 ligand for C2 symmetry-based HIV protease inhibitors, as exemplified in the drug ritonavir. Here we report that incorporation of this P3 ligand into a piperazine hydroxyethylamine series also yielded novel, highly potent inhibitors. In tissue culture assays, the presence of human serum was less deleterious to the activity of these inhibitors than to that of ritonavir. Furthermore, potent activity against ritonavir resistant HIV was observed.

ABT-378, a highly potent inhibitor of the human immunodeficiency virus protease

The valine at position 82 (Val 82) in the active site of the human immunodeficiency virus (HIV) protease mutates in response to therapy with the protease inhibitor ritonavir. By using the X-ray crystal structure of the complex of HIV protease and ritonavir, the potent protease inhibitor ABT-378, which has a diminished interaction with Val 82, was designed. ABT-378 potently inhibited wild-type and mutant HIV protease (Ki = 1.3 to 3.6 pM), blocked the replication of laboratory and clinical strains of HIV type 1 (50% effective concentration [EC50], 0.006 to 0.017 microM), and maintained high potency against mutant HIV selected by ritonavir in vivo (EC50, 50-fold after 8 h. In healthy human volunteers, coadministration of a single 400-mg dose of ABT-378 with 50 mg of ritonavir enhanced the area under the concentration curve of ABT-378 in plasma by 77-fold over that observed after dosing with ABT-378 alone, and mean concentrations of ABT-378 exceeded the EC50 for >24 h. These results demonstrate the potential utility of ABT-378 as a therapeutic intervention against AIDS.

Human serum attenuates the activity of protease inhibitors toward wild-type and mutant human immunodeficiency virus

The potency of therapeutic regimens containing human immunodeficiency virus (HIV) protease inhibitors is related to the ability to maintain concentrations of drug in the plasma of patients that are sufficient for blocking viral replication. The estimation of concentrations required for in vivo activity using in vitro assays is complicated by the fact that extensive binding of many protease inhibitors to serum proteins attenuates their antiviral potency. To provide insight into the relative in vivo potency of current protease inhibitors, we assayed their in vitro activity against wild-type and mutant HIV in the presence of human serum (HS). Using this assay, ABT-378, a new protease inhibitor with trough levels in humans far in excess of the EC50 in the presence of 50% HS, was identified. The antiviral activity of ABT-378 was only modestly attenuated by HS, in contrast to ritonavir, saquinavir, and nelfinavir. Examination of the effect of individual serum components suggested that the activity of ABT-378 is affected predominantly by binding to alpha1-acid glycoprotein (AGP) while the activity of ritonavir is modulated by both AGP and albumin. The method described here may provide insight into the in vivo potency of protease inhibitors and be useful for the preclinical evaluation and selection of new protease inhibitors for clinical studies.

Internal ribosomal entry site scanning of the poliovirus polyprotein: implications for proteolytic processing

Based on previous studies of dicistronic polioviruses carrying two internal ribosomal entry sites (IRESes), we performed a novel experiment of IRES scanning through a polypeptide by inserting sequentially the IRES of encephalomyocarditis virus into the open reading frame (ORF) of the poliovirus polyprotein at selected 3Cpro-specific Q*G cleavage sites. No cytopathic effects were observed after transfection of HeLa cells with any of the dicistronic constructs, and no virus was recovered. In vitro translation of the dicistronic RNA transcripts in HeLa cell-free extracts revealed that multiple defects in the processing of the P2-P3 domain of the polyprotein is the primary reason for the lethal phenotypes. Surprisingly, the interruption of 3Cpro-catalyzed cleavages downstream of 2C interfered with the 2Apro-catalyzed, primary cleavage between P1 and P2. In contrast, insertion of a foreign coding sequence (V3 loop of human immunodeficiency virus type 1 gp120) into the ORF of the polyprotein at the 2C-3A junction yielded a viable virus that appeared to be genetically stable over several passages. The results of these experiments, which are generally applicable to analyses of viral polyproteins or multidomain polypeptides, suggest that processing of the P2-P3 domain by 3C-3CDpro is rapid and accurate only in the context of the unperturbed P2-P3 precursor; this is consistent with cleavages occurring in cis. Moreover, an intact 2C-3A precursor is not required for viral proliferation.

In vitro selection and characterization of human immunodeficiency virus type 1 variants with increased resistance to ABT-378, a novel protease inhibitor

ABT-378, a new human immunodeficiency virus type 1 (HIV-1) protease inhibitor which is significantly more active than ritonavir in cell culture, is currently under investigation for the treatment of AIDS. Development of viral resistance to ABT-378 in vitro was studied by serial passage of HIV-1 (pNL4-3) in MT-4 cells. Selection of viral variants with increasing concentrations of ABT-378 revealed a sequential appearance of mutations in the protease gene: I84V-L10F-M46I-T91S-V32I-I47V. Further selection at a 3.0 microM inhibitor concentration resulted in an additional change at residue 47 (V47A), as well as reversion at residue 32 back to the wild-type sequence. The 50% effective concentration of ABT-378 against passaged virus containing these additional changes was 338-fold higher than that against wild-type virus. In addition to changes in the protease gene, sequence analysis of passaged virus revealed mutations in the p1/p6 (P1' residue Leu to Phe) and p7/p1 (P2 residue Ala to Val) gag proteolytic processing sites. The p1/p6 mutation appeared in several clones derived from early passages and was present in all clones obtained from passage P11 (0.42 microM ABT-378) onward. The p7/p1 mutation appeared very late during the selection process and was strongly associated with the emergence of the additional change at residue 47 (V47A) and the reversion at residue 32 back to the wild-type sequence. Furthermore, this p7/p1 mutation was present in all clones obtained from passage P17 (3.0 microM ABT-378) onward and always occurred in conjunction with the p1/p6 mutation. Full-length molecular clones containing protease mutations observed very late during the selection process were constructed and found to be viable only in the presence of both the p7/p1 and p1/p6 cleavage-site mutations. This suggests that mutation of these gag proteolytic cleavage sites is required for the growth of highly resistant HIV-1 selected by ABT-378 and supports recent work demonstrating that mutations in the p7/p1/p6 region play an important role in conferring resistance to protease inhibitors (L. Doyon et al., J. Virol. 70:3763-3769, 1996; Y. M. Zhang et al., J. Virol. 71:6662-6670, 1997).

Brefeldin A inhibits cell-free, de novo synthesis of poliovirus

Brefeldin A (BFA), an inhibitor of intracellular vesicle-dependent secretory transport, is a potent inhibitor of poliovirus RNA replication in infected cells. We have determined that the unknown mechanism of BFA inhibition of replication is reproduced in the cell-free poliovirus translation, replication, and encapsidation system. Furthermore, we provide evidence suggesting that the cellular mechanism targeted by BFA, the GTP-dependent synthesis of secretory transport vesicles, may be involved in viral RNA replication in the system via a soluble cellular GTP-binding and -hydrolyzing activity. This activity is related to the ARF (ADP-ribosylation factor) family of GTP-binding proteins. ARFs are required for the formation of several classes of secretory vesicles, and some family members are indirectly inactivated by BFA. Peptides that function as competitive inhibitors of ARF activity in cell-free transport systems also inhibit poliovirus RNA replication, and this inhibitory effect can be countered by the addition of exogenous ARF. We suggest that BFA inhibition of replication is diagnostic of a requirement for ARF activity in the cell-free system.

Adhesion of mature polyploid megakaryocytes to fibronectin is mediated by beta 1 integrins and leads to cell damage

Human CD34+ bone marrow cells were committed to the megakaryocytic lineage in serum-free liquid cultures by the following cytokines: thrombopoietin, erythropoietin, and IL-6. Megakaryocyte maturation has been described as being regulated by the extracellular matrix. These cells express receptors for laminin, collagen, and vitronectin, but they selectively adhere to and spread on fibronectin, a major component of the bone marrow environment. Function-perturbing antibodies against beta 1 integrins totally abolished the adhesion of megakaryocytes on fibronectin, whereas antibodies to beta 3 did not, suggesting that beta 1 integrins were responsible for the adhesive phenotype of these polyploid cells. beta 1-positive clusters were visualized in close contact with the extremities of stress fibers at the cell surface. In the course of cell spreading, we observed morphological modifications such as the disorganization of the compact nuclei structure and the appearance of holes in the cytoplasm leading to the release of alpha IIb beta 3-positive cellular fragments. This process appeared to be a specific feature of megakaryocytes and is correlated neither to apoptosis nor to integrin signaling.

The duration of viral suppression during protease inhibitor therapy for HIV-1 infection is predicted by plasma HIV-1 RNA at the nadir

OBJECTIVE

To determine markers that are associated with the durability of virologic response to therapy with HIV protease inhibitors in HIV-infected individuals.

DESIGN

This study encompassed two retrospective analyses of the duration of virologic response to protease inhibitor therapy. The first analysis included 29 patients receiving either monotherapy or combination therapy with the protease inhibitor ritonavir whose plasma HIV RNA levels rebounded from the point of greatest decline with mutations associated with resistance to ritonavir. The second analysis included a cohort of 102 patients who initially responded to randomized treatment with either monotherapy with ritonavir or combination therapy with ritonavir and zidovudine.

METHODS

Durability of response was defined as the time from the initiation of therapy to the point at which plasma HIV RNA displayed a sustained increase of at least 0.6 log10 copies/ml from the nadir value. In the first analysis, durability of response was analyzed with respect to baseline HIV RNA, HIV RNA at the nadir, and the drop in HIV RNA from baseline to the nadir. In the second analysis, time to rebound was examined using Kaplan-Meier analysis, stratifying by either baseline HIV RNA or HIV RNA at the nadir.

RESULTS

In both analyses, the durability of response was not highly associated with either baseline RNA or the magnitude of RNA decline from baseline. Instead, a strong relationship was observed between the durability of response and the nadir plasma HIV-1 RNA value (P < 0.01). The nadir in viral load was generally reached after 12 weeks of randomized therapy.

CONCLUSIONS

Viral RNA determinations at intermediate timepoints may be prognostic of impending virologic failure of protease inhibitor therapy. Therapeutic strategies that allow intensification of initial antiretroviral regimens in the subset of patients with incomplete virological response before the emergence of high level resistance should be investigated.

Calcium/calmodulin-dependent protein kinase II controls alpha5beta1 integrin-mediated inside-out signaling

Fibronectin binding on alpha5beta1 integrin is strictly dependent on intracellular calcium. Using an in vitro assay, we previously found that either calcineurin inhibitors or a blocking calcineurin monoclonal antibody added to cell lysates completely abolished the fibronectin/integrin interaction, which suggested that the activity of calcineurin, a calcium/calmodulin-dependent phosphatase, was required to counteract some kinase activity and maintain the high affinity state of alpha5beta1. In this paper, we show that blocking of the calcium/calmodulin kinase II (CaMKII) activity with the specific inhibitor KN-62 or with its pseudosubtrate Autocamtide-2 preserved the high affinity state of the integrin even under experimental conditions that inhibit calcineurin. Conversely, the addition of purified CaMKII to the cell lysate inhibited alpha5beta1 binding to fibronectin in vitro. Consistent with these results, cell adhesion on fibronectin was stimulated by KN-62. Moreover, Scatchard analysis of fibronectin binding on CHO cells revealed that KN-62 decreased the Kd value from 0.3 to 0.05 microM. Finally the expression of exogenous constitutively active CaMKII resulted in a dramatic defect in cell adhesion with no significant modification in alpha5beta1 cell surface expression. In summary our results demonstrate that CaMKII controls the affinity state of the integrin alpha5beta1 in vitro and in living cells.

Discovery of ritonavir, a potent inhibitor of HIV protease with high oral bioavailability and clinical efficacy

The structure-activity studies leading to the potent and clinically efficacious HIV protease inhibitor ritonavir are described. Beginning with the moderately potent and orally bioavailable inhibitor A-80987, systematic investigation of peripheral (P3 and P2') heterocyclic groups designed to decrease the rate of hepatic metabolism provided analogues with improved pharmacokinetic properties after oral dosing in rats. Replacement of pyridyl groups with thiazoles provided increased chemical stability toward oxidation while maintaining sufficient aqueous solubility for oral absorption. Optimization of hydrophobic interactions with the HIV protease active site produced ritonavir, with excellent in vitro potency (EC50 = 0.02 microM) and high and sustained plasma concentrations after oral administration in four species. Details of the discovery and preclinical development of ritonavir are described.

Discovery of ritonavir, a potent inhibitor of HIV protease with high oral bioavailability and clinical efficacy

The structure-activity studies leading to the potent and clinically efficacious HIV protease inhibitor ritonavir are described. Beginning with the moderately potent and orally bioavailable inhibitor A-80987, systematic investigation of peripheral (P3 and P2') heterocyclic groups designed to decrease the rate of hepatic metabolism provided analogues with improved pharmacokinetic properties after oral dosing in rats. Replacement of pyridyl groups with thiazoles provided increased chemical stability toward oxidation while maintaining sufficient aqueous solubility for oral absorption. Optimization of hydrophobic interactions with the HIV protease active site produced ritonavir, with excellent in vitro potency (EC50 = 0.02 microM) and high and sustained plasma concentrations after oral administration in four species. Details of the discovery and preclinical development of ritonavir are described.

Autologous dendritic cells derived from CD34+ progenitors and from monocytes are not functionally equivalent antigen-presenting cells in the induction of melan-A/Mart-1(27-35)-specific CTLs from peripheral blood lymphocytes of melanoma patients with low frequency of CTL precursors

Peptide presentation by autologous dendritic cells (DCs) is a new tool to activate tumor antigen-specific T cells in melanoma patients. However, it is not known whether autologous DCs, differentiated by two of the most efficient protocols (from CD34+ progenitors or from monocytes), are equally effective as professional antigen-presenting cells (APCs) when the patients have a low frequency of peptide-specific precursors. To this end, a limiting dilution assay was applied to evaluate the frequency of antigen-specific CTL precursors (CTLps) in peripheral blood of HLA-A*0201+ melanoma patients. Then, from two melanoma patients showing low frequency of CTLps to melanoma antigen-A/melanoma antigen recognized by T cell (Melan-A/Mart-1)(27-35) peptide, autologous DCs were differentiated from granulocyte colony-stimulating factor-mobilized CD34+ progenitors or from monocytes. CD34+- and monocyte-derived DCs were characterized by a similar proportion of CD1a+ cells expressing HLA class II antigens and CD54, CD80, and CD86 molecules. Both types of DC presented Melan-A/Mart-1(27-35) and tyrosinase(369-377) peptides to melanoma-specific CTL clones and were equally effective as peptide-pulsed APCs in the activation of influenza A matrix(58-66)-specific CTLs from high-frequency precursors (1294/10(6) and 1789/10(6) lymphocytes in the two patients). However, efficient activation of Melan-A/Mart-1(27-35)-specific CTLs from low-frequency precursors (158/10(6) and 77/10(6) lymphocytes) of the two patients was markedly dependent on the use of peptide-loaded CD34+-derived DCs. These results suggest that CD34+- and monocyte-derived DCs are not functionally equivalent APCs for the activation of low-frequency peptide-specific CTLps.

Expression and function of receptors for extracellular matrix molecules in the differentiation of human megakaryocytes in vitro

The role of adhesive interactions with the extracellular matrix components of the bone marrow (BM) stroma has been widely studied in the differentiation of erythroid and myelomonocytic cells, but not in the megakaryocytic lineage. The development of efficient culture techniques for the production of megakaryocytes (Mks) from CD34+ purified BM cells, enables the study of the expression and function of adhesion receptors for collagen (VLA-2), fibronectin (VLA-4 and VLA-5) and laminin (VLA-6) during the maturation of Mks. We have shown that a significant percentage of CFU-MK (roughly 20%) adhere to fibronectin but not to collagen and laminin. The expression and adhesion of Mks developing in liquid culture from BM-CD34+ cells were tested at days 4, 7 and 10 of incubation. The expression of VLA-2, VLA-5 and VLA-6 on day 10 cultured Mks enabled purification of intermediate and large polyploid Mks by FACS sorting whereas VLA-4 appeared to label only immature Mks and myeloid cells. We observed that only a small proportion of mature Mks was able to adhere to collagen without spreading at day 10 of culture, whereas 30% of Mks adhered to fibronectin as early as day 4 of incubation, 40% of which also attached to laminin. Our data suggest that VLA-4 may be involved in the adhesion of CFU-MK and immature Mks on fibronectin, then replaced by VLA-5 in the final stages of maturation. The expression of VLA-6 and the number of adherent Mks on laminin increased sharply between day 7 and 10 of incubation. A number of mature polyploid Mks found in day 10 of culture exhibited characteristic features of intense spreading on laminin and fibronectin which were not observed on collagen.

Multiple-dose pharmacokinetics of ritonavir in human immunodeficiency virus-infected subjects

The multiple-dose pharmacokinetics of ritonavir were investigated in four groups of human immunodeficiency virus-positive male subjects (with 16 subjects per group) under nonfasting conditions; a 3:1 ritonavir:placebo ratio was used. Ritonavir was given at 200 (group I), 300 (group II), 400 (group III), or 500 (group IV) mg every 12 h for 2 weeks. The multiple-dose pharmacokinetics of ritonavir were moderately dose dependent, with the clearance for group IV (6.8 +/- 2.7 liters/h) being an average of 32% lower than that for group I (10.0 +/- 3.2 liters/h). First-pass metabolism should be minimal for ritonavir. The functional half-life, estimated from peak and trough concentrations, were similar among the dosage groups, averaging 3.1 and 5.7 h after the morning and evening doses, respectively. The area under the concentration-time curve at 24 h (AUC24) and apparent terminal-phase elimination rate constant remained relatively time invariant, but predose concentrations decreased 30 to 70% over time. Concentration-dependent autoinduction is the most likely mechanism for the time-dependent pharmacokinetics. The Km and initial maximum rate of metabolism (Vmax) values estimated from population pharmacokinetic modeling (nonlinear mixed-effects models) were 3.43 microg/ml and 46.9 mg/h, respectively. The group IV Vmax increased to 68 mg/h after 2 weeks. The maximum concentration of ritonavir in serum (Cmax) and AUC after the evening doses were an average of 30 to 40% lower than the values after the morning doses, while the concentration at 12 h was an average of 32% lower than the predose concentration, probably due to protracted absorption. Less than 2% of the dose was eliminated unchanged in the urine. Triglyceride levels increased from the levels at the baseline, and the levels were correlated with baseline triglyceride levels and AUC, Cmax, or predose concentrations.

Impact of a single megadose of vitamin A at delivery on breastmilk of mothers and morbidity of their infants

OBJECTIVES

To evaluate the effect of vitamin A supplementation 24 h after delivery on breastmilk retinol concentration.

METHODS

Fifty low income women were randomly assigned to a single oral dose of 209 micromol of Vitamin A or none at delivery. Maternal serum and breastmilk retinol levels and infant morbidity and anthropometry were serially assessed.

RESULTS

Mean (95% CI) serum retinol levels increased in the supplemented mothers at 2.77 (2.3, 3.2) compared to 1.15 (0.9, 1.4) micromol/l in controls (P < 0.05) and remained at a significantly higher level of 1.59 (1.4, 1.8) micromol/l compared to 1.33 (1.8, 1.5) micromol/l in the control group (P < 0.001) up to a period of three months. Breastmilk retinol concentration was also greater at 24 h after supplementation, mean (CI) 11.34 (9.0, 13.7) micromol/l, compared to 2.95 (2.3, 3.6) micromol/l in the control group (P < 0.0001), and remained higher for the next six months at 1.06 (0.9, , 1.3) micromol/l compared to 0.73 (0.6, 0.8) micromol/l in the control group (P < 0.02). Infants of the supplemented mothers had reduced mean duration of respiratory tract infection of 3.1 (2.7, 3.5) days compared to 3.7 (3.3, 4.2) days (P < 0.03) and mean incidence of febrile illness 0.1 (0.1, 0.1) compared to control infants 0.3 (0.3, 0.3) days, (P < 0.002).

CONCLUSION

Vitamin A supplementation of malnourished mothers maintains higher breastmilk retinol concentration for at least six months and reduces the duration of respiratory tract infection and febrile illness in their breastfed infants.

Novel azacyclic ureas that are potent inhibitors of HIV-1 protease

A series of novel, azacyclic ureas which are highly potent inhibitors of the HIV-1 protease (IC50 = 4.1 to < 0.5 nM) were synthesized. Aqueous solubilities of this series of compounds were improved by incorporating polar functional groups at the P1' P2 and P2' positions. These compounds also possess good anti-viral activity by inhibition of the cytopathic effect of HIV-13B in MT-4 cells in vitro.

Ordered accumulation of mutations in HIV protease confers resistance to ritonavir

Analysis of the HIV protease gene from the plasma of HIV-infected patients revealed substitutions at nine different codons selected in response to monotherapy with the protease inhibitor ritonavir. Mutants at valine-82, although insufficient to confer resistance, appeared first in most patients. Significant phenotypic resistance required multiple mutations in HIV protease, which emerged subsequently in an ordered, stepwise fashion. The appearance of resistance mutations was delayed in patients with higher plasma levels of ritonavir. Early mutants retained susceptibility to structurally diverse protease inhibitors, suggesting that dual protease inhibitor therapy might increase the duration of viral suppression.

A novel, picomolar inhibitor of human immunodeficiency virus type 1 protease

The design, synthesis, and molecular modeling studies of a novel series of azacyclic ureas, which are inhibitors of human immunodeficiency virus type 1 (HIV-1) protease that incorporate different ligands for the S1', S2, and S2' substrate-binding sites of HIV-1 protease are described. The synthesis of this series is highly flexible in the sense that the P1', P2, and P2' residues of the inhibitors can be changed independently. Molecular modeling studies on the phenyl ring of the P2 and P2' ligand suggested incorporation of hydrogen-bonding donor/acceptor groups at the 3' and 4-positions of the phenyl ring should increase binding potency. This led to the discovery of compound 7f (A-98881), which possesses high potency in the HIV-1 protease inhibition assay and the in vitro MT-4 cell culture assay (Ki = approximately 5 pM and EC50 = 0.002 microM). This compares well with the symmetrical cyclic urea 1 pioneered at DuPont Merck.

Cotranscription of two RNA coding for the cell adhesion regulator and its variant in Reh leukemia cells

Human genomic DNA analysis reveals the existence of polymorphisms at the cell molecular adhesion regulator (CMAR) locus. In order to choose between the two possible open frames deduced from the variant sequence, we have sequence both the human 5' non-coding region and the mouse CMAR variant DNA. We found that both mRNA species coexist in human cells.

Beta 1 integrins mediate adherent phenotype of human erythroblastic cell lines after phorbol 12-myristate 13-acetate induction

We investigated the effects of phorbol ester (phorbol 12-myristate 13-acetate; PMA) treatment on the adhesive behaviour of three erythroleukaemia cell lines: HEL, LAMA-84 and AP217. In the three cell lines PMA induced an increase in expression of a megakaryocytic marker: alpha IIb beta 3 integrin, but did not promote activation of this receptor. Indeed, an antibody specific for the activated form of alpha IIb beta 3 failed to react with the three cell lines. PMA induction led to different adhesive phenotypes depending on the cell line; in fact LAMA-84 and HEL cells became adherent while AP217 cells remained non-adherent. By studying cell surface receptors we found that the major difference between the adherent and the non-adherent cells was the expression of beta 1 integrins. After PMA induction, beta 1 integrin expression was totally abolished in AP217 cells and the amount of beta 1 mRNA was reduced preventing new synthesis of the subunit. In HEL and LAMA-84 cells, PMA treatment did not alter the overall level of beta 1 integrin but induced a new pattern of alpha-subunit expression: up-regulation of alpha 2 and alpha v subunits and down-regulation of alpha 4 and alpha 5 subunits. Function-perturbing antibodies against beta 1, alpha 4, alpha 5, alpha v and alpha 2 reduced adhesion of HEL cells to fibronectin or collagen, whereas antibodies against beta 3 or alpha v beta 3 did not. Our results favour the involvement of beta 1 integrins in PMA-induced adhesion of erythroleukaemia cells.

Rice oral rehydration solution hastens recovery from dysentery

Using a three-cell study design over two years, we assessed the efficacy of rice ORS (R-ORS) for home management of dysentery in rural Bangladesh involving 1,911 children of less than five years of age who were matched for socioeconomic status, morbidity, nutrition and other factors. Dysentery was defined as passing blood and/or mucus in the stool, and the total numbers of episodes studies were: 1472, 1335, and 1557 in the R-ORS, glucose ORS (G-ORS), and comparison areas respectively. Packaged R-ORS and G-ORS were supplied free of cost. The comparison area continued the usual treatment of dysentery as practised in the community. During the two-year period, weekly observations were made in all areas on the incidence, management, and outcome of all episodes of dysentery. We demonstrated that the use of R-ORS was associated with reduction in duration and a lower incidence of prolonged diarrhoea compared to treatment with G-ORS or drugs. The mean durations of dysenteric diarrhoea were 7.6 +/- 4.9, 10.1 +/- 6.3, and 14.0 +/- 8.0 days in the R-ORS, G-ORS, and comparison areas respectively. Similarly, the cumulative recovery rates on day 7 of the illness were 61%, 42% and 21% in R-ORS, G-ORS, and comparison areas respectively. Based on these observations, we conclude that R-ORS may be an effective treatment of dysentery and deserves further investigation.

Stimulation of poliovirus proteinase 3Cpro-related proteolysis by the genome-linked protein VPg and its precursor 3AB

Purified recombinant poliovirus polypeptide 3AB interacts with 3CDpro and 3Dpol as shown by coimmunoprecipitation with anti-3Dpol antibodies. A consequence of this interaction is an accelerated autoprocessing of 3CDpro to produce 3Cpro and 3Dpol. The activation of 3Dpol polymerase activity by cleavage of 3CDpro, a polypeptide that has no polymerase activity, can be shown by template- and primer-dependent poly(U) synthesis. Anti-VPg antibodies (VPg = 3B) added to HeLa translation extracts programmed with poliovirion RNA inhibit cleavage of 3CDpro whereas addition of purified 3AB or VPg to these translation reactions increases 3CDpro processing. 3AB stimulates also 3Cpro-related proteolysis of 2BC, a poliovirus-specific, nonstructural processing intermediate. In contrast, 3CDpro-specific cleavage of the structural precursor P1 is inhibited by the addition of 3AB as shown by a decrease in the production of VP0 and VP3. These data shed new light on a phenomenon in the regulation of expression of poliovirus genetic information: whereas the proteinase 3CDpro is needed for processing of the capsid precursor, the cleavage product of this relatively stable precursor is required for RNA replication.

Is rice based oral rehydration therapy effective in young infants?

Rice based oral rehydration therapy (ORT) solutions have been shown to be superior to glucose oral rehydration salts (World Health Organisation (WHO) ORS) in reducing stool volume and duration of diarrhoea in children and adults. Rice based ORT has been used only sparingly in young infants, however, because of theoretical concerns about digestibility. A randomised controlled trial of rice based ORT (50 g rice and electrolytes identical to WHO ORS) and WHO ORS was carried out in 52 male infants less than 6 months old with moderately severe acute diarrhoea to evaluate efficacy and digestibility. Nineteen (70%) of 27 children who received rice based ORT and 18 (72%) of 25 children who received WHO ORS were treated successfully. The mean (SD) diarrhoeal stool output for the first 24 hours of treatment was significantly lower in the infants receiving the rice based ORT than in those receiving WHO ORS (101.0 (60.5) v 137.1 (74.6) g/kg). The stool output was also significantly less in the rice based ORT group in the second 24 hours. Infants in the rice based ORT group drank significantly less rehydration solution than infants in the WHO ORS group (mean (SD) 165.4 (77.4) v 217.9 (86.1) during the first 24 hours of treatment. There was no difference in the duration of diarrhoea between the groups. The volume of breast and formula feeding was similar in the two groups. No difference was seen in the frequency of finding reducing substances or acid pH in the stools of either group of children. The results suggest that rice based ORT is as effective as WHO ORS in infants with moderately severe diarrhoea and that rice based ORT is as well tolerated as WHO ORS in infants.

Pattern of dyslipoproteinemia in selected population of Karachi

Pattern of dyslipoproteinemia was studied, over a period of 3-1/2 years in 487 (394 males, 93 females) cases aged 4 to above 70 years. Type IV hyperlipoproteinemia was most prevalent (36%) followed by type V (15%).

Cardiovascular risk factors in school children from low middle income families in Karachi, Pakistan

Serum levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and triglycerides (TG) were determined on 239 school children aged 5-19 years belonging to lower middle class families. The mean TC, LDL-C, HDL-C and TG ranged from 3.70-4.37 mmol/L, 2.17-2.70 mmol/L, 0.94-1.14 mmol/L, 1.07-1.26 mmol/L respectively. In general, girls had higher TC, LDL-C and HDL-C levels. There was no significant difference in the TG levels between boys and girls. Thirty-three percent of the girls and 22% of the boys had TC level > or = 4.4 mmol/L, the level at which dietary intervention is recommended for children. Fifty-three percent of the girls and 37% of the boys had TG levels > or = than the 90th percentile of the levels for children of similar age and sex in North America. The HDL-C levels were low with 37% of the girls and 44% of boys having values < or = the 10th percentile of levels for North American children. The mean daily intake of cholesterol ranged from 241 mg to 364 mg/day. Except for the 5-9 year olds, boys had a higher cholesterol intake than girls (P < 0.005). Twenty-two percent of the boys and 32% of the girls were overweight but weight status was significantly associated with elevated TC levels only in the boys (P < 0.05). Activity level was not significantly related to TC levels but girls who were active had significantly higher HDL-C levels than girls who were sedentary (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of a putative amphipathic helix in the N-terminus of poliovirus protein 2C

Poliovirus protein 2C contains near its N-terminus a putative amphipathic helix which is well conserved among picornaviruses. Three mutants were constructed within this region by site-directed mutagenesis. In the first mutant (pT7XL2-2C-N1) two glutamic acids were replaced with valines at the boundary of the charged and uncharged faces of the helix. The second mutant (pT7XL2-2C-N2) contains an isoleucine to lysine change in the hydrophobic half; in the third mutant (pT7XL2-2C-N3) two lysines were replaced with threonines in the hydrophilic half of the helix. Upon transfection of HeLa cells with RNA transcripts made from these plasmids only pT7XL2-2C-N1 yielded viable virus (W1-2C-N1) which had a small-plaque phenotype. A large-plaque revertant of this virus, W1-2C-N1R, was found to contain the original glutamic acid at one of the mutated sites (E19). There is no detectable minus-stranded RNA synthesis following transfection of HeLa cells with transcript RNAs of the other two plasmids, pT7XL2-2C-N2 and -N3. In vitro translation of these two mutant RNA transcripts in HeLa extracts revealed processing abnormalities in the P2/P3 region of the polyprotein. This leads to a nearly complete absence of 2C and 3AB, which might be the primary cause of defective viral RNA synthesis. The putative amphipathic helix was found to overlap a consensus binding site for double-stranded RNA.

The impact of nutritional counselling on serum lipids, dietary and physical activity patterns of school children

Eighty-eight school children and their parents who had been counselled regarding appropriate dietary and activity patterns aimed at reducing serum cholesterol were followed-up 21 months later to determine changes in dietary and activity patterns and in serum lipid levels. The decline in serum total cholesterol ranged from 8 to 14% in the different age and sex groups (P < 0.05 to P < 0.001). Serum triglycerides did not change significantly. Cholesterol intake decreased 36% and 54% in 10-14 year old boys and girls respectively (P > 0.001). The activity level increased significantly in both the 5-9 year and 10-14 year olds (P < 0.05 to P < 0.005). These results show that nutrition education can bring about a change in dietary and activity patterns, resulting in a decline in serum cholesterol levels.

Studies on dicistronic polioviruses implicate viral proteinase 2Apro in RNA replication

A dicistronic poliovirus W1-P1/E/P2,3-1 with the genotype [PV]5'NTR-P1-[EMCV]IRES-[PV]P2,3-3'NTR (Molla, Jang, Paul, Reuer, and Wimmer, 1992, Nature 356, 255) was used to investigate whether the viral proteinase 2Apro, whose primary function in proteolytic processing was erased through the insertion of an internal ribosomal entry site (IRES) element into the ORF of the polyprotein, had other function(s) in viral replication. Deletion of 2Apro from W1-P1/E/P2,3-1 rendered the corresponding transcripts unable to replicate whereas partial deletion of 2Apro or an exchange of Cys109 (an amino acid of the catalytic triad of the proteinase) to Ala reduced RNA replication. No cytopathic effects were observed after transfection with any of the three dicistronic constructs containing mutant 2A, and no virus was recovered after attempts to expand a possibly low yield of mutant virus. In contrast, insertion of the IRES of encephalomyocarditis virus (EMCV) into the ORF of the poliovirus polyprotein at the cleavage site between 2Apro and 2B yielded the novel dicistronic virus W1-P1,2A/E/2BC,P3-1 with the genotype [PV]5'NTR-P1-2A-[EMCV]IRES-[PV]2BC-P3-3'NTR, expressing a small plaque phenotype. These results indicate that neither the intact P2 polypeptide nor the cleavage fragment 2AB of P2 is required for viral proliferation. On the other hand, 2Apro appears to be an essential component in RNA replication as no viral RNA synthesis can be observed by reverse transcription/PCR in cells transfected with dicistronic RNA lacking this viral polypeptide.

Effects of temperature and lipophilic agents on poliovirus formation and RNA synthesis in a cell-free system

The translation and primary processing events of poliovirus polyproteins in HeLa cell extracts were more efficient at 34 degrees C than at 30 or 36 degrees C. The cleavage products of P2 such as 2Apro, 2BC, and 2C appeared early in the reaction before the appearance of the cleavage products of P1 and of 3CDpro, an observation suggesting that P2 was cleaved in cis by 3CDpro. Proteolytic processing of the capsid precursor P1 into VP0, VP1, and VP3 was also more efficient at 34 degrees C than at either 30 or 32 degrees C. Surprisingly, processing of 3CDpro to 3Cpro and 3Dpol was almost completely inhibited at 36 degrees C. The synthesis of virus in the cell extract was greatly enhanced at 34 degrees C over that at 30 or 32 degrees C, whereas incubation at 36 degrees C yielded very little virus. Cerulenin, an inhibitor of lipid synthesis, did not appear to affect virus-specific translation or protein processing, but it almost completely inhibited viral synthesis in vitro. Oleic acid drastically inhibited in vitro translation at 100 microM and in vitro poliovirus synthesis at 25 microM. Addition of HeLa cell smooth membranes partially restored translation but not virus formation. Our observations suggest that in vitro translation, proteolytic processing, and virus formation require intact membranes. Analysis of the in vitro translation products revealed that viral RNA polymerase activity increased linearly during incubation of the translation mixture. RNA polymerase in the crude mixture was inhibited by oleic acid but not by cerulenin. Surprisingly, oleic acid had no direct effect on oligo(U)-primed, poly(A)-dependent poly(U) synthesis catalyzed by purified 3Dpol.

Does red blood cell distribution width (RDW) improve evaluation of microcytic anaemias?

The red cell distribution width (RDW) is an index of the variation in red cells size (anisocytosis). A study was conducted to examine the validity of using RDW in improving classification of microcytic anaemias. A total of 300 blood samples collected from a patient population aged 3 months to 55 years who were referred for haemoglobin electrophoresis were examined at the Aga Khan University Hospital (AKUH). On complete blood count, initially 200 patients (66.6%) were found to have hypochromic microcytic anaemia. Following haemoglobin electrophoresis 41% (82/200) patients were diagnosed to have thalassemia minor and 59% (118/200) had hypochromic microcytic anaemia with either a normal haemoglobin pattern or an abnormal haemoglobin. The mean (+/- SD) RDW estimated in 250 apparently healthy Pakistani population was 14 (+/- 1.5%). Elevated RDW of 23% was present in 94% (110/118) of the patients with hypochromic microcytic anaemia due to other causes, whereas 48% (39/82) of the patients with thalassemia minor had elevated RDW of 16%. Also, of the 82 thalassemia minor, 28 patients had normal haemoglobin level, of which 6 had elevated RDW and of the 54 with low haemoglobin level, 35 had elevated RDW. RDW was normal in 41 patients with thalassemia minor trait. Our results suggest that RDW alone cannot be used as a reliable indicator to distinguish between thalassemia minor and other causes of microcytosis.